WO2021107159A1 - Water-absorbent sheet and absorbent article including same - Google Patents

Water-absorbent sheet and absorbent article including same Download PDF

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Publication number
WO2021107159A1
WO2021107159A1 PCT/JP2020/044517 JP2020044517W WO2021107159A1 WO 2021107159 A1 WO2021107159 A1 WO 2021107159A1 JP 2020044517 W JP2020044517 W JP 2020044517W WO 2021107159 A1 WO2021107159 A1 WO 2021107159A1
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Prior art keywords
water
base material
absorbent
absorbing agent
absorbing
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PCT/JP2020/044517
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French (fr)
Japanese (ja)
Inventor
達史 平内
遼亮 藤川
貞巖 ▲より▼元
貴洋 北野
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株式会社日本触媒
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Application filed by 株式会社日本触媒 filed Critical 株式会社日本触媒
Priority to CN202080082864.6A priority Critical patent/CN114746058A/en
Priority to JP2021561588A priority patent/JP7410175B2/en
Priority to CN202311262915.5A priority patent/CN117257553A/en
Publication of WO2021107159A1 publication Critical patent/WO2021107159A1/en
Priority to ZA2022/05800A priority patent/ZA202205800B/en
Priority to JP2023215752A priority patent/JP2024026458A/en

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/53—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
    • A61F13/534—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad
    • A61F13/535—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad inhomogeneous in the plane of the pad, e.g. core absorbent layers being of different sizes
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/53—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/53—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
    • A61F13/534—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
    • B01J20/26—Synthetic macromolecular compounds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/22—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof comprising organic material
    • B01J20/26—Synthetic macromolecular compounds
    • B01J20/261—Synthetic macromolecular compounds obtained by reactions only involving carbon to carbon unsaturated bonds
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
    • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
    • B01J20/00—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof
    • B01J20/28—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties
    • B01J20/28014—Solid sorbent compositions or filter aid compositions; Sorbents for chromatography; Processes for preparing, regenerating or reactivating thereof characterised by their form or physical properties characterised by their form
    • B01J20/28016—Particle form
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/44—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties the fleeces or layers being consolidated by mechanical means, e.g. by rolling
    • D04H1/46—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties the fleeces or layers being consolidated by mechanical means, e.g. by rolling by needling or like operations to cause entanglement of fibres
    • D04H1/492—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties the fleeces or layers being consolidated by mechanical means, e.g. by rolling by needling or like operations to cause entanglement of fibres by fluid jet
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/54—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/53—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
    • A61F2013/530131—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium being made in fibre but being not pulp
    • A61F2013/530226—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium being made in fibre but being not pulp with polymeric fibres
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/53—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
    • A61F2013/530131—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium being made in fibre but being not pulp
    • A61F2013/530379—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium being made in fibre but being not pulp comprising mixtures of fibres
    • A61F2013/530386—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium being made in fibre but being not pulp comprising mixtures of fibres with pulp and polymeric
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/53—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
    • A61F2013/530481—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/53—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
    • A61F2013/530481—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials
    • A61F2013/530489—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials being randomly mixed in with other material
    • A61F2013/530496—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having superabsorbent materials, i.e. highly absorbent polymer gel materials being randomly mixed in with other material being fixed to fibres
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/53—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
    • A61F2013/530868—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium characterized by the liquid distribution or transport means other than wicking layer
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/53—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium
    • A61F13/534—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad
    • A61F2013/53445—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the absorbing medium having an inhomogeneous composition through the thickness of the pad from several sheets

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Analytical Chemistry (AREA)
  • Organic Chemistry (AREA)
  • Epidemiology (AREA)
  • Biomedical Technology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Vascular Medicine (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Textile Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Absorbent Articles And Supports Therefor (AREA)
  • Laminated Bodies (AREA)

Abstract

[Problem] To provide a novel water-absorbent sheet with which it is possible to significantly reduce liquid discharge from the water-absorbent sheet caused by reversal, even when there is intermittent entry of liquid a plurality of times (in particular, three or more times). [Solution] A water-absorbent sheet having a first base material, a second base material, and a water-absorbent layer positioned between the first base material and the second base material, wherein the water-absorbent layer includes a particulate water absorbent, the surface of the first base material forms a water-absorbent surface that directly absorbs liquid, and the ratio (thickness (mm) of first base material/thickness (mm) of second base material) of the thickness (mm) of the first base material to the thickness (mm) of the second base material is at least 1.5 and less than 14.

Description

吸水性シートおよびそれを含む吸収性物品Water-absorbent sheet and absorbent articles containing it
　本発明は、吸水性シートおよびそれを含む吸収性物品に関する。 The present invention relates to a water-absorbent sheet and an absorbent article containing the same.
　吸水性樹脂（ＳＡＰ／Ｓｕｐｅｒ　Ａｂｓｏｒｂｅｎｔ　ｐｏｌｙｍｅｒ）は、水膨潤性水不溶性の高分子ゲル化剤であり、紙オムツ、生理用ナプキンや成人向け失禁用製品等の衛生材料、農園芸用の土壌保水剤、工業用の止水剤等、様々な用途に利用されている。 Water-absorbent resin (SAP / Super Absorbent polymer) is a water-swellable water-insoluble polymer gelling agent, which is a sanitary material such as disposable diapers, sanitary napkins and incontinence products for adults, and a soil water-retaining agent for agriculture and gardening. , Industrial water-stopping agent, etc., are used for various purposes.
　これら吸収性物品は一般に紙オムツ製造工場にて吸水性樹脂と繊維材料を混合して吸収性物品ごとに個々に型取りした吸収体として製造されており、目的に応じて種々の形状の吸収体（例えば、平面に見て砂時計型、キツネ型、楕円型等）に加工されている。これら吸収体の製造方法は個々に型取りするため任意の形に加工でき、吸収性物品ごとに繊維や吸水性樹脂の量も調整し易いため、現在の紙オムツの主流となっている。 These absorbent articles are generally manufactured in a paper diaper manufacturing factory as an absorber in which a water-absorbent resin and a fiber material are mixed and individually molded for each absorbent article, and have various shapes depending on the purpose. (For example, it is processed into an hourglass type, a diaper type, an oval type, etc. when viewed on a flat surface). Since these absorbents are individually molded, they can be processed into any shape, and the amount of fibers and water-absorbent resin can be easily adjusted for each absorbent article, which is the mainstream of the current paper diapers.
　しかし、近年、紙オムツの製造で、２枚のシート間に吸水性樹脂を固定化した長尺の吸水性シートを衛生材料の製造工程で裁断した吸収体（吸水性シートと呼称、通常は幅１０ｃｍ前後で長さ数１０ｃｍの長方形に裁断）を用いた紙オムツが製造されるようになってきた。紙オムツメーカーは、長尺の連続吸水性シートを購入または製造することで、紙オムツの製造工程を簡便化でき、さらにパルプを用いないことで紙オムツを薄型化することができる。吸水性シートは上下のシート（特に不織布シート）間に吸水性樹脂粒子をサンドイッチおよび固定化する構成をとり、通常長尺連続シートを製造した後に長尺連続シートを裁断して幅１０ｃｍ前後で長さ数１０ｃｍの長方形とし、紙オムツに組み込む（例えば、国際公開第２０１０／１４３６３５号）。 However, in recent years, in the manufacture of paper omelets, an absorber (called a water-absorbent sheet, usually width) obtained by cutting a long water-absorbent sheet in which a water-absorbent resin is immobilized between two sheets in the manufacturing process of a sanitary material. Paper omelets using (cut into a rectangle with a length of about 10 cm and a length of several tens of centimeters) have come to be manufactured. Paper diaper makers can simplify the manufacturing process of paper diapers by purchasing or manufacturing long continuous water-absorbent sheets, and can make paper diapers thinner by not using pulp. The water-absorbent sheet has a structure in which water-absorbent resin particles are sandwiched and fixed between the upper and lower sheets (particularly a non-woven fabric sheet), and after usually producing a long continuous sheet, the long continuous sheet is cut to have a width of about 10 cm. Make a rectangle with a length of several tens of centimeters and incorporate it into a paper diaper (for example, International Publication No. 2010/143635).
　従来の衛生材料（紙オムツ）と違って、吸水性シートによる紙オムツはその歴史が浅いこともあり、吸水性シートに適した吸水性樹脂の開発やパラメーターの提案は殆ど行われていないのが実情であり、従来の紙オムツ向けの吸水性樹脂が吸水性シートにもそのまま使用されている。 Unlike conventional sanitary materials (paper diapers), paper diapers made of water-absorbent sheets have a short history, and there have been few developments of water-absorbent resins suitable for water-absorbent sheets or proposals for parameters. As a matter of fact, the conventional water-absorbent resin for disposable diapers is used as it is for the water-absorbent sheet.
　本発明者らは、薄型であることが主流の吸水性シートならではの構造上、吸収された液体が、吸水性シートに圧力が加わることにより吸収される液の導入方向に放出される、いわゆる「逆戻り」が生じやすいことを知見した。「逆戻り」はＲｅ－ｗｅｔとも呼ばれる。そして、逆戻りの発生は、断続的に複数回（特に、３回以上）の液の導入があって液の導入量が多くなると、その問題が顕著であることを見出した。逆戻りが生じた場合、吸水性シートと接している肌はその逆戻りした液と接するため、湿気の高い状態に晒される。そのため、使用者は不快感を生じるだけでなく、吸水性シートと接している肌にかぶれも生じやすくなる。 Due to the structure unique to the water-absorbent sheet, which is mainly thin, the present inventors release the absorbed liquid in the introduction direction of the absorbed liquid when pressure is applied to the water-absorbent sheet. It was found that "backtracking" is likely to occur. "Return" is also called Re-wet. Then, it was found that the problem of the occurrence of reversion becomes remarkable when the liquid is introduced intermittently a plurality of times (particularly three times or more) and the amount of the liquid introduced is large. When reversion occurs, the skin in contact with the water-absorbent sheet comes into contact with the reverted liquid and is exposed to a high humidity condition. Therefore, the user not only causes discomfort, but also tends to cause a rash on the skin in contact with the water-absorbent sheet.
　本発明は、上記事情に鑑みてなされたものであり、断続的に複数回（特に、３回以上）の液の導入があっても、逆戻りによる吸水性シートからの液放出を有意に低減することができる、新規な吸水性シートを提供することを目的とする。 The present invention has been made in view of the above circumstances, and even if the liquid is intermittently introduced a plurality of times (particularly three or more times), the liquid discharge from the water-absorbent sheet due to reversion is significantly reduced. It is an object of the present invention to provide a novel water-absorbent sheet capable of providing a new water-absorbent sheet.
　本発明者らは、上記課題を解決するために、鋭意検討を積み重ねた。その結果、第１の基材と、第２の基材と、前記第１の基材と、前記第２の基材との間に位置する吸水層と、を有する、吸水性シートであって、前記吸水層が粒子状吸水剤を含み、前記第１の基材の表面が、液を直接的に吸収する吸液面を形成し、前記第２の基材の厚み（ｍｍ）に対する、前記第１の基材の厚み（ｍｍ）の比（第１の基材の厚み（ｍｍ）／第２の基材の厚み（ｍｍ））が、１．５以上１４未満である、吸水性シートにより、上記課題が解決することを見出した。 The present inventors have made extensive studies in order to solve the above problems. As a result, it is a water-absorbent sheet having a first base material, a second base material, a water-absorbing layer located between the first base material and the second base material. The water-absorbing layer contains a particulate water-absorbing agent, the surface of the first base material forms a liquid-absorbing surface that directly absorbs the liquid, and the thickness (mm) of the second base material is relative to the above. By a water-absorbent sheet in which the ratio of the thickness (mm) of the first base material (thickness of the first base material (mm) / thickness of the second base material (mm)) is 1.5 or more and less than 14. , Found that the above problem can be solved.
　また、本発明の他の形態に係る吸水性シートは、第１の基材と、第２の基材と、前記第１の基材と、前記第２の基材との間に位置する吸水層と、を有する、吸水性シートであって、前記吸水層が粒子状吸水剤を含み、前記第１の基材上には吸水層が配置されておらず、前記第２の基材の厚み（ｍｍ）に対する、前記第１の基材の厚み（ｍｍ）の比（第１の基材の厚み（ｍｍ）／第２の基材の厚み（ｍｍ））が、１．５以上１４未満である。 Further, the water-absorbent sheet according to another embodiment of the present invention is a water-absorbent sheet located between a first base material, a second base material, the first base material, and the second base material. A water-absorbing sheet having a layer, wherein the water-absorbing layer contains a particulate water-absorbing agent, the water-absorbing layer is not arranged on the first base material, and the thickness of the second base material is When the ratio of the thickness (mm) of the first base material to (mm) (thickness of the first base material (mm) / thickness of the second base material (mm)) is 1.5 or more and less than 14. is there.
　さらに、本発明の他の形態に係る吸水性シートは、第１の基材と、第２の基材と、前記第１の基材と、前記第２の基材との間に位置する吸水層と、を有する、吸水性シートであって、前記吸水層が粒子状吸水剤を含み、前記第１の基材上には吸水層が配置されておらず、前記第１の基材の厚みは、０．７ｍｍ以上５ｍｍ以下であって、前記第２の基材の厚み（ｍｍ）に対する、前記第１の基材の厚み（ｍｍ）の比（第１の基材の厚み（ｍｍ）／第２の基材の厚み（ｍｍ））が、１．５以上１４未満である。 Further, the water-absorbent sheet according to another embodiment of the present invention is a water-absorbent sheet located between the first base material, the second base material, the first base material, and the second base material. A water-absorbing sheet having a layer, wherein the water-absorbing layer contains a particulate water-absorbing agent, the water-absorbing layer is not arranged on the first base material, and the thickness of the first base material is Is 0.7 mm or more and 5 mm or less, and the ratio of the thickness (mm) of the first base material to the thickness (mm) of the second base material (thickness (mm) of the first base material / The thickness (mm) of the second base material is 1.5 or more and less than 14.
　本発明のさらに他の形態に係る吸水性シートは、第１の基材と、第２の基材と、前記第１の基材と、前記第２の基材との間に位置する吸水層と、前記第１の基材の表面に配置させるラッピングシートと、を有する、吸水性シートであって、前記吸水層が粒子状吸水剤を含み、前記ラッピングシートの表面が、液を直接的に吸収する吸液面を形成し、前記第２の基材の厚みに対する、前記第１の基材の厚みの比（第１の基材の厚み（ｍｍ）／第２の基材の厚み（ｍｍ））が、１．５以上１４未満である。 The water-absorbent sheet according to still another embodiment of the present invention is a water-absorbent layer located between a first base material, a second base material, the first base material, and the second base material. A water-absorbent sheet comprising, and a wrapping sheet to be arranged on the surface of the first base material, wherein the water-absorbent layer contains a particulate water-absorbing agent, and the surface of the wrapping sheet directly absorbs a liquid. A liquid absorbing surface is formed to absorb, and the ratio of the thickness of the first base material to the thickness of the second base material (thickness of the first base material (mm) / thickness of the second base material (mm). )) Is 1.5 or more and less than 14.
本発明の一実施形態に係る吸水性シートの断面を表す模式図である。It is a schematic diagram which shows the cross section of the water absorption sheet which concerns on one Embodiment of this invention. 本発明の他の実施形態に係る吸水性シートの断面を表す模式図である。It is a schematic diagram which shows the cross section of the water absorption sheet which concerns on other embodiment of this invention. 本発明の他の実施形態に係る吸水性シートの断面を表す模式図である。It is a schematic diagram which shows the cross section of the water absorption sheet which concerns on other embodiment of this invention. 本発明の他の実施形態に係る吸水性シートの断面を表す模式図である。It is a schematic diagram which shows the cross section of the water absorption sheet which concerns on other embodiment of this invention. 不織布に対する粒子状吸水剤の透過率を測定する方法を説明する模式図である。It is a schematic diagram explaining the method of measuring the transmittance of a particulate water absorbing agent with respect to a non-woven fabric. 特定戻り量の評価に用いたサンプルを示した平面図および右側面図であり、実施例で作製した吸水性シートを液体不透過性シートで包む様子を示した図である。It is a plan view and the right side view which showed the sample used for the evaluation of the specific return amount, and is the figure which showed the state of wrapping the water-absorbing sheet produced in an Example with a liquid permeable sheet. 特定戻り量の評価に用いた液注入筒の平面図および正面図である。It is a top view and the front view of the liquid injection cylinder used for evaluation of a specific return amount. 特定戻り量評価において本願の実施例で用いた吸水性シートの上に液注入筒を置いた様子を示した正面図である。It is a front view which showed the state which put the liquid injection cylinder on the water absorption sheet used in the Example of this application in the specific return amount evaluation. 特定戻り量評価において漏斗を使用して液注入筒から塩化ナトリウム水溶液を吸水性シートに投入している様子を示した正面図である。It is a front view which showed the state which the sodium chloride aqueous solution was put into a water absorption sheet from a liquid injection cylinder using a funnel in the specific return amount evaluation. 面方向の漏れ量の評価に用いた装置を示す概略図である。It is the schematic which shows the apparatus used for the evaluation of the leakage amount in a plane direction. 不織布の起毛面積率を測定する方法を説明する模式図である。It is a schematic diagram explaining the method of measuring the raised area ratio of a non-woven fabric. 加圧特定戻り量の評価に用いた液注入筒の平面図および正面図である。It is a top view and the front view of the liquid injection cylinder used for evaluation of a specific pressure return amount. 加圧特定戻り量評価において本願の実施例で用いた吸水性シートの上に液注入筒を置いた様子を示した正面図である。It is a front view which showed the state which put the liquid injection cylinder on the water absorption sheet used in the Example of this application in the pressure specific return amount evaluation. 加圧特定戻り量評価において漏斗を使用して液注入筒から塩化ナトリウム水溶液を吸水性シートに投入している様子を示した正面図である。It is a front view which showed the state which the sodium chloride aqueous solution was put into a water absorption sheet from a liquid injection cylinder using a funnel in the pressure specific return amount evaluation. 実施例で作製した吸水性シートにおける粒子状吸水剤と間隙との形態を説明するための吸水性シートの断面を表す模式図である。It is a schematic diagram which shows the cross section of the water-absorbing sheet for demonstrating the form of the particulate water-absorbing agent and the gap in the water-absorbing sheet produced in an Example. 実施例で作製した吸水性シートにおける粒子状吸水剤と間隙との形態を説明するための吸水性シートの断面を表す模式図である。It is a schematic diagram which shows the cross section of the water-absorbing sheet for demonstrating the form of the particulate water-absorbing agent and the gap in the water-absorbing sheet produced in an Example. 不織布の伸び率を測定する方法を説明する模式図である。It is a schematic diagram explaining the method of measuring the elongation rate of a non-woven fabric. 本発明の第１の実施形態に係る吸水性シートの断面を表す模式図である。It is a schematic diagram which shows the cross section of the water absorption sheet which concerns on 1st Embodiment of this invention. 本発明の第２の実施形態に係る吸水性シートの断面を表す模式図である。It is a schematic diagram which shows the cross section of the water absorption sheet which concerns on 2nd Embodiment of this invention. 実施例で作製した吸水性シートにおける粒子状吸水剤と間隙との形態を説明するための吸水性シートの断面を表す模式図である。It is a schematic diagram which shows the cross section of the water-absorbing sheet for demonstrating the form of the particulate water-absorbing agent and the gap in the water-absorbing sheet produced in an Example. 実施例で作製した吸水性シートにおける粒子状吸水剤と間隙との形態を説明するための吸水性シートの断面を表す模式図である。It is a schematic diagram which shows the cross section of the water-absorbing sheet for demonstrating the form of the particulate water-absorbing agent and the gap in the water-absorbing sheet produced in an Example. 不織布の伸び率を測定する方法を説明する模式図である。It is a schematic diagram explaining the method of measuring the elongation rate of a non-woven fabric. 不織布に対する粒子状吸水剤の透過率を測定する方法を説明する模式図である。It is a schematic diagram explaining the method of measuring the transmittance of a particulate water absorbing agent with respect to a non-woven fabric. 特定戻り量の評価に用いたサンプルを示した平面図および右側面図であり、実施例で作製した吸水性シートを液体不透過性シートで包む様子を示した図である。It is a plan view and the right side view which showed the sample used for the evaluation of the specific return amount, and is the figure which showed the state of wrapping the water-absorbing sheet produced in an Example with a liquid permeable sheet. 特定戻り量の評価に用いた液注入筒の平面図および正面図である。It is a top view and the front view of the liquid injection cylinder used for evaluation of a specific return amount. 特定戻り量評価において本願の実施例で用いた吸水性シートの上に液注入筒を置いた様子を示した正面図である。It is a front view which showed the state which put the liquid injection cylinder on the water absorption sheet used in the Example of this application in the specific return amount evaluation. 特定戻り量評価において漏斗を使用して液注入筒から塩化ナトリウム水溶液を吸水性シートに投入している様子を示した正面図である。It is a front view which showed the state which the sodium chloride aqueous solution was put into a water absorption sheet from a liquid injection cylinder using a funnel in the specific return amount evaluation.
　以下、本発明を最良の形態を示しながら説明する。本明細書の全体にわたり、単数形の表現は、特に言及しない限り、その複数形の概念をも含むことが理解されるべきである。従って、単数形の冠詞（例えば、英語の場合は「ａ」、「ａｎ」、「ｔｈｅ」等）は、特に言及しない限り、その複数形の概念をも含むことが理解されるべきである。また、本明細書において使用される用語は、特に言及しない限り、当該分野で通常用いられる意味で用いられることが理解されるべきである。したがって、他に定義されない限り、本明細書中で使用される全ての専門用語および科学技術用語は、本発明の属する分野の当業者によって一般的に理解されるのと同じ意味を有する。矛盾する場合、本明細書（定義を含めて）が優先する。本発明は、下記の実施形態に限定されるものではなく、特許請求の範囲内で種々改変することができる。 Hereinafter, the present invention will be described while showing the best form. Throughout the specification, it should be understood that the singular representation also includes its plural concept, unless otherwise stated. Therefore, it should be understood that singular articles (eg, "a", "an", "the", etc. in English) also include the plural concept unless otherwise noted. It should also be understood that the terms used herein are used in the meaning commonly used in the art unless otherwise noted. Thus, unless otherwise defined, all terminology and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, this specification (including definitions) takes precedence. The present invention is not limited to the following embodiments, and various modifications can be made within the scope of the claims.
　［第１の発明］
　第１の発明について説明する。第１の発明の吸水性シートは、第１の基材と、第２の基材と、前記第１の基材と、前記第２の基材との間に位置する吸水層と、を有する、吸水性シートであって、前記吸水層が粒子状吸水剤を含み、前記第１の基材の表面が、液を直接的に吸収する吸液面を形成し、前記第２の基材の厚み（ｍｍ）に対する、前記第１の基材の厚み（ｍｍ）の比（第１の基材の厚み（ｍｍ）／第２の基材の厚み（ｍｍ））が、１．５以上１４未満である。 [First invention]
The first invention will be described. The water-absorbent sheet of the first invention has a first base material, a second base material, and a water-absorbent layer located between the first base material and the second base material. , A water-absorbing sheet, wherein the water-absorbing layer contains a particulate water-absorbing agent, and the surface of the first base material forms a liquid-absorbing surface that directly absorbs the liquid, and the second base material has a water-absorbing surface. The ratio of the thickness (mm) of the first base material to the thickness (mm) (thickness of the first base material (mm) / thickness of the second base material (mm)) is 1.5 or more and less than 14. Is.
　〔１．用語の定義〕
　［１－１．吸水性シート］
　本発明における「吸水性シート」とは、長尺の２枚以上の基材間に吸水性樹脂（粒子状吸水剤）が担持された構造物をいう。上記吸水性シートは、基材同士の接着、および／または、基材と粒子状吸水剤との接着に、接着剤を用いていてもよく、ホットメルト接着剤を用いていてもよい。上記吸水性シートは、粒子状吸水剤に加えて、他の成分（繊維成分、抗菌剤、消臭剤など）を含んでいてもよい。粒子状吸水剤などを挟持する２枚の基材以外にも、他のシートを含んでいる吸水性シートがある。本実施形態に対して、本願の発明課題の解決を阻害しない場合に限り、粒子状吸水剤などを挟持する２枚の基材以外にも、他のシートを含んでいる吸水性シートがあってもよい。粒子状吸水剤などを２枚の基材で挟持した吸水性シートが好ましい実施形態である。 [1. Definition of terms〕
[1-1. Water-absorbent sheet]
The "water-absorbent sheet" in the present invention refers to a structure in which a water-absorbent resin (particulate water-absorbent agent) is supported between two or more long base materials. The water-absorbent sheet may use an adhesive or a hot-melt adhesive for adhering the base materials to each other and / or adhering the base material to the particulate water-absorbing agent. The water-absorbent sheet may contain other components (fiber component, antibacterial agent, deodorant, etc.) in addition to the particulate water-absorbing agent. In addition to the two base materials that sandwich the particulate water absorbing agent and the like, there is a water absorbing sheet that contains other sheets. With respect to the present embodiment, there is a water-absorbent sheet containing another sheet in addition to the two base materials sandwiching the particulate water-absorbing agent or the like, as long as it does not hinder the solution of the problem of the present invention. May be good. A water-absorbent sheet in which a particulate water-absorbing agent or the like is sandwiched between two base materials is a preferred embodiment.
　通常、吸水性シートは、連続シート状、または、当該連続シートを巻き取ったロール状である。上記吸水性シートを使用する際には、連続シートを適当な形状（長方形など）に裁断した後に、吸収性物品（紙オムツ、生理用ナプキン、失禁者用パッドなど）に組み込んで使用する。紙オムツ（使い捨てオムツ）、生理用ナプキン、失禁者用パッドなどの吸収性物品は、身体から排泄される尿や経血などの体液を吸収・保持する吸収体と、身体に接する側に配された柔軟な液透過性の表面シートと、身体と接する側と反対側に配された液不透過性の裏面シートとを有している。吸水性シートは、前記の吸収体として使用できる。従来の紙オムツは、紙オムツ一枚ごとに、個々に型取りされた、おしりにフィットするような形状をした吸収性物品である。したがって、このような吸収体は、本発明の吸水性シートとは技術の性質を異にする。 Normally, the water-absorbent sheet is in the form of a continuous sheet or in the form of a roll obtained by winding the continuous sheet. When using the above-mentioned water-absorbent sheet, the continuous sheet is cut into an appropriate shape (rectangular shape, etc.) and then incorporated into an absorbent article (paper diaper, sanitary napkin, incontinence pad, etc.). Absorbent items such as disposable diapers, sanitary napkins, and incontinence pads are placed on the side that comes into contact with the body and the absorber that absorbs and retains body fluids such as urine and menstrual blood excreted from the body. It has a flexible liquid-permeable front sheet and a liquid-impermeable back sheet arranged on the side opposite to the side in contact with the body. The water-absorbent sheet can be used as the absorber. A conventional disposable diaper is an absorbent article that is individually molded for each disposable diaper and has a shape that fits the buttocks. Therefore, such an absorber differs from the water-absorbent sheet of the present invention in technical properties.
　［１－２．吸水性樹脂］
　本明細書において「吸水性樹脂」とは、ＥＲＴ４４１．２－０２により規定される水膨潤性（ＣＲＣ）が５ｇ／ｇ以上であり、およびＥＲＴ４７０．２－０２により規定される水可溶成分（Ｅｘｔ）が５０質量％以下である高分子ゲル化剤をいう。 [1-2. Water-absorbent resin]
As used herein, the term "water-absorbent resin" refers to a water-soluble component having a water swelling property (CRC) of 5 g / g or more as defined by ERT441.2-02 and a water-soluble component defined by ERT470.2-02. Ext) refers to a polymer gelling agent having an Ext) of 50% by mass or less.
　吸水性樹脂は、好ましくは、カルボキシル基を有する不飽和単量体を架橋重合させた、親水性架橋重合体である。上記吸水性樹脂の形状は、シート状、繊維状、フィルム状、粒子状、ゲル状などである。本発明の一実施形態に係る吸水性シートは、粒子状の吸水性樹脂を用いる。 The water-absorbent resin is preferably a hydrophilic crosslinked polymer obtained by crosslinking and polymerizing an unsaturated monomer having a carboxyl group. The shape of the water-absorbent resin is sheet-like, fibrous, film-like, particle-like, gel-like, or the like. The water-absorbent sheet according to the embodiment of the present invention uses a particulate water-absorbent resin.
　本明細書において「吸水性樹脂」とは、全量（１００質量％）が当該吸水性樹脂のみである態様に限定されない。上述のＣＲＣおよびＥｘｔを満足するならば、添加剤などを含んでいる吸水性樹脂組成物であってもよい。また、本明細書において「吸水性樹脂」とは、吸水性樹脂の製造工程における中間体をも包含する概念である。例えば、重合後の含水ゲル状架橋重合体、乾燥後の乾燥重合体、表面架橋前の吸水性樹脂粉末なども、「吸水性樹脂」と表記する場合がある。 In the present specification, the "water-absorbent resin" is not limited to the embodiment in which the total amount (100% by mass) is only the water-absorbent resin. A water-absorbent resin composition containing additives and the like may be used as long as the above-mentioned CRC and Ext are satisfied. Further, in the present specification, the "water-absorbent resin" is a concept including an intermediate in the manufacturing process of the water-absorbent resin. For example, a water-containing gel-like crosslinked polymer after polymerization, a dried polymer after drying, a water-absorbent resin powder before surface cross-linking, and the like may also be referred to as "water-absorbent resin".
　このように、本明細書においては、吸水性樹脂そのものに加えて、吸水性樹脂組成物および中間体をも総称して「吸水性樹脂」と表記する場合がある。 As described above, in the present specification, in addition to the water-absorbent resin itself, the water-absorbent resin composition and the intermediate may be generically referred to as "water-absorbent resin".
　［１－３．吸水剤、粒子状吸水剤］
　本明細書において「吸水剤」とは、吸水性樹脂を主成分として含む、水性液（液）を吸収するための吸収ゲル化剤を意味する。ここで、上記水性液（液）とは水のみならず、水を含む液体であれば特に限定されない。本発明の一実施形態に係る吸水性シートが吸収する水性液は、尿、経血、汗、その他の体液である。 [1-3. Water-absorbing agent, particulate water-absorbing agent]
As used herein, the term "water-absorbing agent" means an absorbing gelling agent for absorbing an aqueous liquid (liquid) containing a water-absorbing resin as a main component. Here, the aqueous liquid (liquid) is not particularly limited as long as it is a liquid containing water as well as water. The aqueous liquid absorbed by the water-absorbent sheet according to the embodiment of the present invention is urine, menstrual blood, sweat, or other body fluid.
　本明細書において「粒子状吸水剤」とは、粒子状（粉末状）の吸水剤を意味する（吸水剤中に吸水性樹脂を主成分として含むため、粒子状の吸水性樹脂に相当する）。「粒子状吸水剤」の概念には、一粒の粒子状吸水剤と、複数個の粒子状吸水剤の集合体との、いずれもが包含される。本明細書において「粒子状」とは、粒子の形態を有することを意味する。ここで、「粒子」とは、物質の比較的小さな分割体を指し、数Å～数ｍｍの大きさを有している（「粒子」、マグローヒル科学技術用語大辞典編集委員会　編『マグローヒル科学技術用語大辞典　第３版』、日刊工業新聞社、１９９６年、１９２９頁を参照）。本発明において、吸水剤の形態は粒子状吸水剤に制限されない。本明細書では、本発明を、粒子状吸水剤を例に説明するが、「粒子状吸水剤」は「吸水剤」として読み替えることができる。なお、本明細書では、「粒子状吸水剤」を単に「吸水剤」と表記することがある。 In the present specification, the "particulate water-absorbing agent" means a particulate (powder-like) water-absorbing agent (corresponding to a particulate water-absorbing resin because the water-absorbing agent contains a water-absorbent resin as a main component). .. The concept of "particulate water-absorbing agent" includes both a single particle-like water-absorbing agent and an aggregate of a plurality of particulate water-absorbing agents. As used herein, the term "particulate" means having the form of particles. Here, "particle" refers to a relatively small fragment of a substance, and has a size of several Å to several mm ("particle", edited by the editorial committee of the McGraw-Hill Science and Technology Glossary Dictionary, "Maglow Hill Science". See Technical Term Dictionary, 3rd Edition, Nikkan Kogyo Shimbun, 1996, p. 1929). In the present invention, the form of the water absorbing agent is not limited to the particulate water absorbing agent. In the present specification, the present invention will be described by taking a particulate water-absorbing agent as an example, but the “particulate water-absorbing agent” can be read as a “water-absorbing agent”. In addition, in this specification, "particulate water absorption agent" may be simply referred to as "water absorption agent".
　本発明の吸水性シートにおいて、前記粒子状吸水剤の重量平均粒子径が、２００～６００μｍである。ここで、粒子状吸水剤の重量平均粒子径が２００μｍ未満であると取り扱い性が低下する虞がある。また、粒子状吸水剤の重量平均粒子径が６００μｍを超えると吸水性シートの風合いが低下する虞がある。本発明の一実施形態に係る吸水性シートにおいて、前記粒子状吸水剤の重量平均粒子径が、好ましくは２５０～５００μｍであり、より好ましくは３００～４５０μｍである。また、本発明の吸水性シートにおいて、粒子状吸水剤全体の９５質量％以上が８５０μｍ以下の粒子径であることが好ましく、粒子状吸水剤全体の９８質量％以上が８５０μｍ以下の粒子径であることがより好ましく、粒子状吸水剤全体の実質的に１００質量％が８５０μｍ以下の粒子径であることがさらに好ましい。なお、本願の実施例では、粒子状吸水剤全体の実質的に１００質量％が８５０μｍ以下の粒子径である。ここで、本明細書中、重量平均粒子径の測定方法は、ＥＲＴ４２０．２－０２に規定される「ＰＳＤ」の測定方法に従って得られたＰＳＤに基づいて米国特許第７６３８５７０号に記載された「（３）Ｍａｓｓ－Ａｖｅｒａｇｅ　Ｐａｒｔｉｃｌｅ　Ｄｉａｍｅｔｅｒ　（Ｄ５０）　ａｎｄ　Ｌｏｇａｒｉｔｈｍｉｃ　Ｓｔａｎｄａｒｄ　Ｄｅｖｉａｔｉｏｎ　（σζ）　ｏｆ　Ｐａｒｔｉｃｌｅ　Ｄｉａｍｅｔｅｒ　Ｄｉｓｔｒｉｂｕｔｉｏｎ」と同様の方法で算出する。 In the water-absorbent sheet of the present invention, the weight average particle size of the particulate water-absorbent is 200 to 600 μm. Here, if the weight average particle size of the particulate water absorbing agent is less than 200 μm, the handleability may be deteriorated. Further, if the weight average particle diameter of the particulate water absorbing agent exceeds 600 μm, the texture of the water absorbing sheet may deteriorate. In the water-absorbent sheet according to the embodiment of the present invention, the weight average particle size of the particulate water-absorbing agent is preferably 250 to 500 μm, more preferably 300 to 450 μm. Further, in the water-absorbent sheet of the present invention, 95% by mass or more of the entire particulate water-absorbing agent preferably has a particle size of 850 μm or less, and 98% by mass or more of the entire particulate water-absorbent agent has a particle size of 850 μm or less. It is more preferable that substantially 100% by mass of the entire particulate water absorbing agent has a particle size of 850 μm or less. In the examples of the present application, substantially 100% by mass of the entire particulate water absorbing agent has a particle size of 850 μm or less. Here, in the present specification, the method for measuring the weight average particle size is described in US Pat. No. 7,638,570 based on the PSD obtained according to the method for measuring "PSD" defined in ERT420.2-02. (3) Mass-Average Particle Diameter (D50) and Logarithmic Standard Deviation (σζ) of Particle Diameter Measurement ”is calculated by the same method.
　粒子状吸水剤は、重合体としての吸水性樹脂（もしくは、粒子状の吸水性樹脂、吸水性樹脂粒子とも言う）を主成分として含む。上記粒子状吸水剤は、重合体としての吸水性樹脂を、６０～１００質量％、好ましくは７０～１００質量％、より好ましくは８０～１００質量％、さらに好ましくは９０～１００質量％、特に好ましくは９５～１００質量％含む。上記粒子状吸水剤の残部は、水、添加剤（無機微粒子、多価金属カチオンなど）などを任意に含んでもよい。なお、本願の実施例で使用した粒子状吸水剤には、吸水性樹脂が８０～１００質量％含まれている。 The particulate water-absorbing agent contains a water-absorbent resin as a polymer (also referred to as a particulate water-absorbent resin or water-absorbent resin particles) as a main component. The particulate water absorbing agent contains 60 to 100% by mass, preferably 70 to 100% by mass, more preferably 80 to 100% by mass, still more preferably 90 to 100% by mass, particularly preferably a water absorbing resin as a polymer. Contains 95-100% by mass. The remainder of the particulate water absorbing agent may optionally contain water, additives (inorganic fine particles, polyvalent metal cations, etc.) and the like. The particulate water-absorbing agent used in the examples of the present application contains 80 to 100% by mass of a water-absorbent resin.
　すなわち、粒子状吸水剤中の吸水性樹脂の上限は、例えば、１００質量％、９９質量％、９７質量％、９５質量％、９０質量％である。そして、好ましくは、吸水性樹脂以外に０～１０質量％の成分、特に水、添加剤（無機微粒子、多価金属カチオン）などをさらに含む。 That is, the upper limit of the water-absorbent resin in the particulate water-absorbing agent is, for example, 100% by mass, 99% by mass, 97% by mass, 95% by mass, and 90% by mass. Then, preferably, in addition to the water-absorbent resin, 0 to 10% by mass of components, particularly water, additives (inorganic fine particles, polyvalent metal cations) and the like are further contained.
　なお、粒子状吸水剤の好ましい含水率は、０．２～３０質量％である。上記に説明した通り、水や添加剤などの成分が吸水性樹脂と一体化している、および／または、混合している状態の吸水性樹脂組成物も、「粒子状吸水剤」に包含される。 The preferable water content of the particulate water absorbent is 0.2 to 30% by mass. As described above, the water-absorbent resin composition in which components such as water and additives are integrated with and / or mixed with the water-absorbent resin is also included in the "particulate water-absorbent agent". ..
　粒子状吸水剤の主成分となる吸水性樹脂の例としては、ポリアクリル酸（塩）系樹脂、ポリスルホン酸（塩）系樹脂、無水マレイン酸（塩）系樹脂、ポリアクリルアミド系樹脂、ポリビニルアルコール系樹脂、ポリエチレンオキシド系樹脂、ポリアスパラギン酸（塩）系樹脂、ポリグルタミン酸（塩）系樹脂、ポリアルギン酸（塩）系樹脂、デンプン系樹脂、セルロース系樹脂が挙げられる。このうち、好ましくは、ポリアクリル酸（塩）系樹脂が吸水性樹脂として使用される。 Examples of water-absorbent resins that are the main components of particulate water-absorbents include polyacrylic acid (salt) -based resins, polysulfonic acid (salt) -based resins, maleic anhydride (salt) -based resins, polyacrylamide-based resins, and polyvinyl alcohol. Examples thereof include based resins, polyethylene oxide-based resins, polyaspartic acid (salt) -based resins, polyglutamic acid (salt) -based resins, polyarginic acid (salt) -based resins, starch-based resins, and cellulose-based resins. Of these, a polyacrylic acid (salt) -based resin is preferably used as the water-absorbent resin.
　［１－４．ポリアクリル酸（塩）］
　本明細書において「ポリアクリル酸（塩）」とは、ポリアクリル酸および／またはその塩を指す。上記ポリアクリル酸（塩）は、主成分として、アクリル酸および／またはその塩（以下、「アクリル酸（塩）」と称する）の繰り返し単位を含み、任意成分としてグラフト成分をさらに含む、重合体である。上記ポリアクリル酸（塩）は、アクリル酸（塩）の重合、ポリアクリルアミドやポリアクリニトリルなどの加水分解、などによって得られる。好ましくは、上記ポリアクリル酸（塩）は、アクリル酸（塩）の重合によって得られる。 [1-4. Polyacrylic acid (salt)]
As used herein, the term "polyacrylic acid (salt)" refers to polyacrylic acid and / or a salt thereof. The polyacrylic acid (salt) is a polymer containing a repeating unit of acrylic acid and / or a salt thereof (hereinafter referred to as "acrylic acid (salt)") as a main component and further containing a graft component as an optional component. Is. The polyacrylic acid (salt) is obtained by polymerization of acrylic acid (salt), hydrolysis of polyacrylamide, polyacrylonitrile, or the like. Preferably, the polyacrylic acid (salt) is obtained by polymerization of acrylic acid (salt).
　ここで、「主成分として含む」とは、ポリアクリル酸（塩）を重合する際のアクリル酸（塩）の使用量が、重合に用いられる単量体（ただし、内部架橋剤を除く）全体に対して、通常５０～１００モル％、好ましくは７０～１００モル％、より好ましくは９０～１００モル％、さらに好ましくは実質的に１００モル％であることをいう。 Here, "included as a main component" means that the amount of acrylic acid (salt) used when polymerizing polyacrylic acid (salt) is the entire monomer (however, excluding the internal cross-linking agent) used for polymerization. On the other hand, it is usually 50 to 100 mol%, preferably 70 to 100 mol%, more preferably 90 to 100 mol%, still more preferably substantially 100 mol%.
　［１－５．ＥＤＡＮＡおよびＥＲＴ］
　「ＥＤＡＮＡ」は、欧州不織布工業会（Ｅｕｒｏｐｅａｎ　Ｄｉｓｐｏｓａｂｌｅｓ　ａｎｄ　Ｎｏｎｗｏｖｅｎｓ　Ａｓｓｏｃｉａｔｉｏｎｓ）の略称である。「ＥＲＴ」は、ＥＤＡＮＡが制定している、欧州標準（実質的な世界標準）の吸水性樹脂の測定法（ＥＤＡＮＡ　Ｒｅｃｏｍｍｅｎｄｅｄ　Ｔｅｓｔ　Ｍｅｔｈｏｄｓ）の略称である。本明細書では、特に断りのない限り、２００２年版のＥＲＴに準拠して、吸水性樹脂の物性を測定する。 [1-5. EDANA and ERT]
"EDANA" is an abbreviation for European Disposables and Nonwovens Associations. "ERT" is an abbreviation for EDANA Recommended Test Methods, which is a European standard (substantially a global standard) for measuring water-absorbent resins. In this specification, unless otherwise specified, the physical characteristics of the water-absorbent resin are measured in accordance with the 2002 version of ERT.
　［１－６．その他］
　本明細書において、範囲を示す「Ｘ～Ｙ」は「Ｘ以上、Ｙ以下」を意味する。 [1-6. Others]
In the present specification, "XY" indicating a range means "X or more and Y or less".
　本明細書において、特に注釈のない限り、質量の単位である「ｔ（トン）」は「メートルトン（Ｍｅｔｒｉｃ　ｔｏｎ）」を意味する。「ｐｐｍ」は、「質量ｐｐｍ」を意味する。「質量」と「重量」、「質量部」と「重量部」、「質量％」と「重量％」、「質量ｐｐｍ」と「重量ｐｐｍ」は、それぞれ同じ意味として扱う。 In this specification, unless otherwise specified, the unit of mass, "t (ton)", means "metric ton". "Ppm" means "mass ppm". "Mass" and "weight", "mass part" and "parts by weight", "mass%" and "weight%", "mass ppm" and "weight ppm" are treated as having the same meaning, respectively.
　本明細書において、「～酸（塩）」は「～酸および／またはその塩」を意味する。「（メタ）アクリル」は「アクリルおよび／またはメタクリル」を意味する。 In the present specification, "-acid (salt)" means "-acid and / or a salt thereof". "(Meta) acrylic" means "acrylic and / or methacrylic".
　本明細書においては、体積の単位「リットル」を「ｌ」または「Ｌ」と表記する場合がある。「質量％」を「ｗｔ％」と表記することがある。微量成分の測定を行う場合において、検出限界以下をＮ．Ｄ．（Ｎｏｎ　Ｄｅｔｅｃｔｅｄ）と表記する。 In this specification, the unit of volume "liter" may be expressed as "l" or "L". "Mass%" may be expressed as "wt%". When measuring trace components, N.I. D. Notated as (Non Directed).
　〔２．吸水性シート〕
　本発明の吸水性シートは、第１の基材と、第２の基材と、前記第１の基材と、前記第２の基材との間に位置する吸水層と、を有する、吸水性シートであって、前記吸水層が粒子状吸水剤を含み、前記第１の基材の表面が、液を直接的に吸収する吸液面を形成し、前記第２の基材の厚み（ｍｍ）に対する前記第１の基材の厚み（ｍｍ）の比（第１の基材の厚み（ｍｍ）／第２の基材の厚み（ｍｍ））が、１．５以上１４未満である。 [2. Water-absorbent sheet]
The water-absorbent sheet of the present invention has a first base material, a second base material, and a water-absorbent layer located between the first base material and the second base material. In the sex sheet, the water absorbing layer contains a particulate water absorbing agent, the surface of the first base material forms a liquid absorbing surface that directly absorbs the liquid, and the thickness of the second base material ( The ratio of the thickness (mm) of the first base material to the thickness (mm) of the first base material (thickness of the first base material (mm) / thickness of the second base material (mm)) is 1.5 or more and less than 14.
　かかる構成によって、断続的に複数回（特に、３回以上）の液の導入があって液の導入量が多くなっても、逆戻りによる吸水性シートからの液放出を有意に低減することができる。本発明の吸水性シートは、液を直接的に吸収する吸液面を形成する第１の基材の厚み（ｍｍ）が、第２の基材の厚み（ｍｍ）に対して１．５以上１４未満である。すなわち、第１の基材は第２の基材よりも有意に厚い。この第２の基材よりも有意に厚い第１の基材の表面に、液を直接的に吸収する吸液面が形成される。ここで、本明細書中、「直接的」とは、他の基材等を浸透してきた液を順次吸収する形態を含まない。なお、本明細書中、第１の基材の表面に後述のラッピングシートが配置された場合も、第１の基材の表面が、液を直接的に吸収する吸液面を形成する形態に包含される。 With such a configuration, even if the liquid is introduced intermittently a plurality of times (particularly three times or more) and the amount of the liquid introduced is large, the liquid release from the water-absorbent sheet due to reversion can be significantly reduced. .. In the water-absorbent sheet of the present invention, the thickness (mm) of the first base material forming the liquid-absorbing surface that directly absorbs the liquid is 1.5 or more with respect to the thickness (mm) of the second base material. It is less than 14. That is, the first substrate is significantly thicker than the second substrate. A liquid absorbing surface that directly absorbs the liquid is formed on the surface of the first base material that is significantly thicker than the second base material. Here, in the present specification, "directly" does not include a form in which a liquid that has permeated another base material or the like is sequentially absorbed. In the present specification, even when the wrapping sheet described later is arranged on the surface of the first base material, the surface of the first base material forms a liquid absorbing surface that directly absorbs the liquid. Included.
　本発明の別の形態において、第１の基材の表面が直接的に吸収する吸液面であるため、第１の基材上には吸水層が配置されていない。よって、本発明の一実施形態に係る吸水性シートは、第１の基材と、第２の基材と、前記第１の基材と、前記第２の基材との間に位置する吸水層と、を有する、吸水性シートであって、前記吸水層が粒子状吸水剤を含み、前記第１の基材上には吸水層が配置されておらず、前記第２の基材の厚みに対する、前記第１の基材の厚みの比（第１の基材の厚み（ｍｍ）／第２の基材の厚み（ｍｍ））が、１．５以上１４未満である。本形態において、吸水層に含有されていた粒子状吸水剤の一部が第１の基材を透過して第１の基材上に移動して一部露出しても、それは吸水層が配置されているとはみなさない。なお、当該移動の要因は、例えば、吸水性シートが最終製品となり、輸送や運搬がなされて生じた振動などが想定される。前記第１の基材上に粒子状吸水剤を意図的に散布または配置したような場合は、本形態の範疇ではない。 In another embodiment of the present invention, since the surface of the first base material is a liquid absorbing surface that is directly absorbed, the water absorbing layer is not arranged on the first base material. Therefore, the water-absorbent sheet according to the embodiment of the present invention absorbs water located between the first base material, the second base material, the first base material, and the second base material. A water-absorbing sheet having a layer, wherein the water-absorbing layer contains a particulate water-absorbing agent, the water-absorbing layer is not arranged on the first base material, and the thickness of the second base material is The ratio of the thickness of the first base material to the thickness of the first base material (thickness of the first base material (mm) / thickness of the second base material (mm)) is 1.5 or more and less than 14. In this embodiment, even if a part of the particulate water-absorbing agent contained in the water-absorbing layer permeates the first base material and moves onto the first base material and is partially exposed, the water-absorbing layer is arranged. Not considered to be done. It is assumed that the cause of the movement is, for example, vibration generated when the water-absorbent sheet is the final product and is transported or transported. When the particulate water absorbing agent is intentionally sprayed or arranged on the first base material, it is not in the category of this embodiment.
　本発明者らは、従来の吸水性シート（例えば、薄型の吸水性シートとするために、第１の基材と第２の基材との厚みが同じ吸水性シート）においては、本願の実施例における特定条件での逆戻り量の測定（本明細書中、「特定戻り量評価」とも称する）において、逆戻り量が顕著に多いことを見出した。つまり、断続的に複数回（特に、３回以上）の液の導入があると、通常の構成であれば、液量が設定の吸収量以上となって過剰な「戻り」が発生してしまう。これに対し、本発明では、液導入側の第１の基材を第２の基材に比べて有意に厚くすることにより、第１の基材の吸液面と、吸水層との距離を長くすることができ、これにより、吸液面より導入された液を、吸液面上に滞留することなく（さらには、導入した液を局所的に滞ることなく）、吸水機能を担う下層の吸水層に液を効率的に送り込むことができる。具体的には、第１の基材中を液が通過する際において液の面方向の拡散性が高く、拡散された液（例えば、尿）を、吸水層の表面全体に広く隈なく移行する（マイグレートする）からと考えられる。すなわち、吸収された液が吸水層に到達する際には、液は面方向に拡散されており、ゆえに、液が多量に吸水層に導入されても、吸水層は局所でなく面方向に広がった液を吸収することになる。よって、吸水層において十分に液を吸収および保持することができる。従来の吸収体に含有していた親水性パルプの液拡散性機能を、前記の第１の基材に付与しているとも考えられる。そして、いったん液が吸水層に吸液されると、第１の基材が有意に厚いために、吸水層で吸収した液が逆戻りして第１の基材の吸液面まで逆戻りすることを有意に低減することができ、これにより逆戻りした液が肌まで上がる（肌に接する）ことを抑制することできる。一方、第２の基材を第１の基材に比べて有意に厚くしても本発明の所期の効果を得ることができない。その理由は不明であり、換言すれば、当業者にとっても予期せぬ効果といえる。 The present inventors carry out the present application in a conventional water-absorbent sheet (for example, a water-absorbent sheet having the same thickness of the first base material and the second base material in order to obtain a thin water-absorbent sheet). In the measurement of the amount of reversion under specific conditions in the example (also referred to as "specific return amount evaluation" in the present specification), it was found that the amount of reversion is remarkably large. In other words, if the liquid is introduced intermittently multiple times (particularly three or more times), the liquid amount will exceed the set absorption amount and excessive "return" will occur in the normal configuration. .. On the other hand, in the present invention, the distance between the liquid absorption surface of the first base material and the water absorption layer is increased by making the first base material on the liquid introduction side significantly thicker than the second base material. It can be lengthened so that the liquid introduced from the water absorption surface does not stay on the water absorption surface (furthermore, the introduced liquid does not stay locally), and the lower layer is responsible for the water absorption function. The liquid can be efficiently delivered to the water absorption layer. Specifically, when the liquid passes through the first base material, the liquid has high diffusivity in the surface direction, and the diffused liquid (for example, urine) is widely and uniformly transferred to the entire surface of the water absorption layer. It is thought that it is because of (migrating). That is, when the absorbed liquid reaches the water absorption layer, the liquid is diffused in the surface direction. Therefore, even if a large amount of the liquid is introduced into the water absorption layer, the water absorption layer spreads in the surface direction instead of locally. It will absorb the liquid. Therefore, the liquid can be sufficiently absorbed and retained in the water absorption layer. It is also considered that the liquid diffusible function of the hydrophilic pulp contained in the conventional absorber is imparted to the first base material. Then, once the liquid is absorbed by the water-absorbing layer, since the first base material is significantly thick, the liquid absorbed by the water-absorbing layer reverts and returns to the liquid-absorbing surface of the first base material. It can be significantly reduced, and thereby it is possible to prevent the retreated liquid from rising to the skin (contacting the skin). On the other hand, even if the second base material is significantly thicker than the first base material, the desired effect of the present invention cannot be obtained. The reason is unknown, in other words, it can be said to be an unexpected effect for those skilled in the art.
　吸水性シートでは、吸水層における吸水機能は主に吸水剤が担うこととなる。特に、吸水層にパルプが存在する従来の吸収性物品と構成が異なる吸水性シートでは、吸水剤の役割が一層重要となる。特に、本発明においては、第１の基材が有意に厚いために、吸水剤にいったん導入された液が第１の基材の吸液面まで戻りにくい。ここで、逆戻りのほかに、面方向の漏れ（横漏れ）があり、横漏れとは、吸水層に到達後、瞬時に吸収しきれなかった液体が、吸水性シートから面方向に漏れ出る現象である。本発明では、粒子状吸水剤がシート（層）状に形成されている利点を生かして、吸水層の面方向の液拡散を最大限に利用することで、第１の基材への逆戻りを抑制しつつ、かつ、吸水性シートからの面方向の漏れ（横漏れ）を抑制する構成となっている。具体的には、本発明においては、第１の基材が第２の基材に比べて有意に厚いため、第１の基材中を液が通過する際において液の面方向の拡散性が高く、拡散された液（例えば、尿）を、吸収速度が有意に高い、言わばタンクのような機能を果たす粒子状吸水剤が面方向に広く隈なく吸収する。すなわち、吸収された液が吸水層に到達する際には、液は面方向に拡散されており、ゆえに、液が多量に吸水層に導入されても、吸水層は局所でなく面方向に広がった液を吸収することになる。よって、吸水層において十分に液を吸収および保持することができ、吸水性シートからの面方向の漏れが有意に低い。そして吸水層が吸収できなかった液が逆戻りしようとしても第１の基材が第２の基材に比べて有意に厚いので、液が肌まで上がることを抑制できる。そのため、「特定戻り量評価」を優れたものとすることができるとともに、面方向の漏れを抑制することができる。ここで、一般条件での逆戻り量を抑制しようと設計された吸水性シートや吸収性物品が、本願の「特定戻り量評価」において必ずしも優れた結果にならないことを付言しておく。また、本発明の一実施形態に係る吸水性シートは、例えば、走ることを覚え始めの、膀胱がまだまだ小さな乳児が昼間等の活動的に動き回っている時間帯に使用する吸収性物品（例えば、オムツ）として好適であるが、無論使用形態がこれに限定されるわけではない。また、本明細書中に記載したメカニズム等が本願の請求の範囲の技術的範囲を限定することはない。 In the water-absorbent sheet, the water-absorbing agent is mainly responsible for the water-absorbing function in the water-absorbing layer. In particular, in a water-absorbent sheet having a structure different from that of a conventional absorbent article in which pulp is present in the water-absorbent layer, the role of the water-absorbing agent becomes even more important. In particular, in the present invention, since the first base material is significantly thick, it is difficult for the liquid once introduced into the water absorbing agent to return to the liquid absorbing surface of the first base material. Here, in addition to the reversion, there is a leakage in the surface direction (lateral leakage), and the lateral leakage is a phenomenon in which the liquid that could not be absorbed instantly after reaching the water absorption layer leaks from the water absorption sheet in the surface direction. Is. In the present invention, by taking advantage of the particle water absorbing agent being formed in the form of a sheet (layer) and maximizing the liquid diffusion in the surface direction of the water absorbing layer, it is possible to revert to the first base material. It is configured to suppress leakage (lateral leakage) in the surface direction from the water-absorbent sheet while suppressing it. Specifically, in the present invention, since the first base material is significantly thicker than the second base material, the diffusivity of the liquid in the surface direction when the liquid passes through the first base material is high. High and diffused liquids (eg, urine) are absorbed widely and evenly in the plane direction by a particulate water absorbent that has a significantly higher absorption rate and acts like a tank. That is, when the absorbed liquid reaches the water absorption layer, the liquid is diffused in the surface direction. Therefore, even if a large amount of the liquid is introduced into the water absorption layer, the water absorption layer spreads in the surface direction instead of locally. It will absorb the liquid. Therefore, the liquid can be sufficiently absorbed and retained in the water absorbing layer, and the leakage from the water absorbing sheet in the plane direction is significantly low. Then, even if the liquid that could not be absorbed by the water absorption layer tries to revert, the first base material is significantly thicker than the second base material, so that the liquid can be prevented from rising to the skin. Therefore, the "specific return amount evaluation" can be made excellent, and leakage in the plane direction can be suppressed. Here, it should be added that a water-absorbent sheet or an absorbent article designed to suppress the amount of reversion under general conditions does not always give excellent results in the "specific return amount evaluation" of the present application. Further, the water-absorbent sheet according to the embodiment of the present invention is an absorbent article (for example, an absorbent article used during a time when an infant whose bladder is still small is actively moving around, such as in the daytime, when he / she begins to learn to run. It is suitable as a diaper), but of course the usage pattern is not limited to this. In addition, the mechanisms and the like described herein do not limit the technical scope of the claims of the present application.
　以下、添付した図面を参照しながら、本発明の実施形態を説明する。なお、図面の説明において同一の要素には同一の符号を付し、重複する説明を省略する。また、図面の寸法比率は、説明の都合上誇張されており、実際の比率とは異なる場合がある。 Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios.
　まず、図１～４に基づいて、吸水性シートの構成を説明する。図１は、本発明の一実施形態に係る吸水性シート１０の、断面を表す模式図である。また、図２～図４は、本発明の他の実施形態に係る吸水性シート１０の、断面を表す模式図である。 First, the configuration of the water-absorbent sheet will be described with reference to FIGS. 1 to 4. FIG. 1 is a schematic view showing a cross section of the water-absorbent sheet 10 according to the embodiment of the present invention. 2 to 4 are schematic views showing a cross section of the water-absorbent sheet 10 according to another embodiment of the present invention.
　図１において、矢印は、吸収される液が導入される方向を示している。第１の基材１１は、吸水層１２に対して吸収される液（吸液される液）が導入される側に位置する。すなわち、第１の基材１１は、液体の排出側（例えば紙オムツでは肌側）に配置される。これにより、第１の基材１１は、液を直接的に吸収する吸液面を形成する。第１の基材１１と第２の基材１３との間に吸水層１２が配置される。 In FIG. 1, the arrow indicates the direction in which the absorbed liquid is introduced. The first base material 11 is located on the side where the liquid absorbed by the water absorbing layer 12 (the liquid to be absorbed) is introduced. That is, the first base material 11 is arranged on the liquid discharge side (for example, the skin side in the case of paper diapers). As a result, the first base material 11 forms a liquid absorbing surface that directly absorbs the liquid. The water absorption layer 12 is arranged between the first base material 11 and the second base material 13.
　図１において、吸水層１２には、粒子状吸水剤１４が含まれる。図１の形態においては、吸水層１２は、第１の基材１１および第２の基材１３の間に粒子状吸水剤１４が存在している状態を示す。吸水層１２は、第１の基材１１に接触している（もしくは、固着している）粒子状吸水剤１４および第２の基材１３に接触している（もしくは、固着している）粒子状吸水剤１４を含む。一部の粒子状吸水剤１４は、各基材１１，１３に接触していなくてもよい（もしくは、固着していなくてもよい。各基材１１，１３から脱離していてもよい）。したがって、吸水「層」とは、シートのような連続体だけを指すのではなく、第１の基材１１および第２の基材１３間に一定の厚さをもって存在するものであればいずれの形態であってもよい。各基材１１，１３に粒子状吸水剤１４を固着させる場合、例えば、接着剤を使用すればよい。接着剤を用いて吸水性シートを製造する方法については、〔３．〕にて詳述する。 In FIG. 1, the water absorbing layer 12 contains the particulate water absorbing agent 14. In the form of FIG. 1, the water absorbing layer 12 shows a state in which the particulate water absorbing agent 14 is present between the first base material 11 and the second base material 13. The water absorption layer 12 is a particle that is in contact with (or is adhered to) the first base material 11 and is in contact with (or is adhered to) the particulate water absorbing agent 14 and the second base material 13. The state water absorbing agent 14 is contained. Some of the particulate water absorbing agents 14 may not be in contact with (or may not be adhered to) the respective base materials 11 and 13, and may be detached from the respective base materials 11 and 13. Therefore, the water-absorbing "layer" does not mean only a continuum such as a sheet, but any one that exists between the first base material 11 and the second base material 13 with a certain thickness. It may be in the form. When the particulate water absorbing agent 14 is fixed to the base materials 11 and 13, for example, an adhesive may be used. For the method of producing a water-absorbent sheet using an adhesive, refer to [3. ] Will be described in detail.
　第１の基材１１内には、粒子状吸水剤１４が存在してもよい。第１の基材１１内の粒子状吸水剤１４としては、例えば、第１の基材１１に接触した（もしくは、固着させた）粒子状吸水剤１４や、第２の基材１３に接触した（もしくは、固着させた）粒子状吸水剤１４が脱離して、第１の基材１１内に捕捉された粒子状吸水剤１４であってもよい。第１の基材内に粒子状吸水剤１４が存在する場合、第１の基材１１中の粒子状吸水剤１４の含有割合は、吸水性シート１０全体に含まれる粒子状吸水剤１４に対して、好ましくは５％以上であり、より好ましくは１０％以上であり、さらに好ましくは２０％以上であり、さらにより好ましくは３０％以上である。なお、上限は特に制限されないが、好ましい順に、９０％以下、７０％以下、５０％以下である。なお、本明細書中、吸水性シート１０全体に含まれる粒子状吸水剤１４に対する第１の基材１１中の粒子状吸水１４剤の含有割合は、後述の実施例の方法により算出される。 The particulate water absorbing agent 14 may be present in the first base material 11. The particulate water absorbing agent 14 in the first base material 11 is, for example, in contact with the particulate water absorbing agent 14 that has come into contact with (or has been fixed to) the first base material 11 or the second base material 13. The particulate water-absorbing agent 14 (or fixed) may be desorbed and captured in the first base material 11. When the particulate water absorbing agent 14 is present in the first base material, the content ratio of the particulate water absorbing agent 14 in the first base material 11 is based on the particulate water absorbing agent 14 contained in the entire water absorbing sheet 10. It is preferably 5% or more, more preferably 10% or more, still more preferably 20% or more, and even more preferably 30% or more. The upper limit is not particularly limited, but is 90% or less, 70% or less, and 50% or less in the preferred order. In the present specification, the content ratio of the particulate water absorbing agent 14 in the first base material 11 to the particulate water absorbing agent 14 contained in the entire water absorbing sheet 10 is calculated by the method of Examples described later.
　吸水性シート１０は、ラッピングシート１６を有する。ラッピングシート１６は、第１の基材１１と第２の基材１３との間で粒子状吸水剤１４が担持された構造物である吸水性シート１０の形状を保持する目的、第１の基材１１と第２の基材１３との間で担持された粒子状吸水剤１４が、吸収体（吸水性シート１０）からこぼれ落ちない（脱落しない）ようにする目的、粒子状吸水剤１４が第１の基材１１を透過し、第１の基材１１の外部表面（液を直接的に吸収する吸液面）に移行した場合、粒子状吸水剤１４が皮膚に直接接触しないようにする目的がある。ラッピングシート１６を有しない場合、例えば、基材１１，１３同士を接着することで封止（シーリング）する方法、第１の基材１１の表面処理により、第１の基材１１の外部表面（液を直接的に吸収する吸液面）への移行を抑制する方法等がある。本願の効果を維持しつつ吸水性シート１０から粒子状吸水剤１４が脱落しない方法として、ラッピングシート１６を有することが好ましい。 The water-absorbent sheet 10 has a wrapping sheet 16. The wrapping sheet 16 is a first group for the purpose of maintaining the shape of the water-absorbent sheet 10, which is a structure in which the particulate water-absorbing agent 14 is supported between the first base material 11 and the second base material 13. For the purpose of preventing the particulate water absorbing agent 14 supported between the material 11 and the second base material 13 from spilling (not falling off) from the absorber (water absorbing sheet 10), the particulate water absorbing agent 14 is the first. The purpose of preventing the particulate water absorbing agent 14 from coming into direct contact with the skin when it permeates the base material 11 of 1 and migrates to the outer surface of the first base material 11 (the water absorbing surface that directly absorbs the liquid). There is. When the wrapping sheet 16 is not provided, for example, by a method of sealing by adhering the base materials 11 and 13 to each other, and by surface treatment of the first base material 11, the outer surface of the first base material 11 ( There is a method of suppressing the transfer to the liquid absorption surface) that directly absorbs the liquid. It is preferable to have the wrapping sheet 16 as a method of preventing the particulate water absorbing agent 14 from falling off from the water absorbing sheet 10 while maintaining the effect of the present application.
　ラッピングシート１６は、第１の基材１１の上に配置され、吸水層１２と第２の基材１３との全体を包み込むように折り重ねられている。よって、ラッピングシート１６は、第１の基材１１、吸水層１２および第２の基材１３の全体を覆っている。かような構成とすることで、粒子状吸水剤１４の吸水性シート１０からの脱落を抑制することができる。なお、ラッピングシート１６は、第１の基材１１、吸水層１２および第２の基材１３の全体を覆う必要はない。例えば、ラッピングシート１６は、第１の基材１１の上に配置され、吸水層１２の側面と第２の基材１３の側面とを包み込むように折り曲げられ、第２の基材１３の吸液される面（すなわち、吸水層１２が設けられた面）と反対側の面に折り重ねられていてもよい。すなわち、ラッピングシート１６は、第２の基材１３の吸水層１２が設けられた面と反対側の面において、ラッピングシート１６の一端と、ラッピングシート１６の他端とが重なっている。この場合、ラッピングシート１６は、第１の基材１１の吸液面と側面と、吸水層１２の側面と、第２の基材１３の側面とを覆い、第２の基材１３の吸水層１２が設けられた面と反対側の面の全体または一部を覆っている。 The wrapping sheet 16 is arranged on the first base material 11, and is folded so as to wrap the entire water absorbing layer 12 and the second base material 13. Therefore, the wrapping sheet 16 covers the entire first base material 11, the water absorption layer 12, and the second base material 13. With such a configuration, it is possible to prevent the particulate water absorbing agent 14 from falling off from the water absorbing sheet 10. The wrapping sheet 16 does not need to cover the entire first base material 11, the water absorption layer 12, and the second base material 13. For example, the wrapping sheet 16 is arranged on the first base material 11, bent so as to wrap the side surface of the water absorbing layer 12 and the side surface of the second base material 13, and absorbs the liquid of the second base material 13. It may be folded on the surface opposite to the surface to be formed (that is, the surface provided with the water absorption layer 12). That is, in the wrapping sheet 16, one end of the wrapping sheet 16 and the other end of the wrapping sheet 16 overlap on the surface of the second base material 13 opposite to the surface on which the water absorption layer 12 is provided. In this case, the wrapping sheet 16 covers the liquid absorbing surface and the side surface of the first base material 11, the side surface of the water absorbing layer 12, and the side surface of the second base material 13, and the water absorbing layer of the second base material 13. It covers all or part of the surface opposite to the surface on which the 12 is provided.
　ここで、ラッピングシート１６は、第２の基材１３の吸水層１２が設けられた面と反対側の面において、ラッピングシート１６の一端と、ラッピングシート１６の他端とが離れていてもよい。例えば、図２では、ラッピングシート１６は、第１の基材１１の上に配置され、吸水層１２の側面と第２の基材１３の側面とを包み込むように折り曲げられ、第２の基材１３の液を直接的に吸収する吸液面（すなわち、吸水層１２が設けられた面）と反対側の面において、ラッピングシート１６の一端と、ラッピングシート１６の他端とが離れて配置されている。この場合、ラッピングシート１６は、第１の基材１１の吸液面と側面と、吸水層１２の側面と、第２の基材１３の側面とを覆い、第２の基材１３の吸水層１２が設けられた面と反対側の面の一部を覆っている。 Here, in the wrapping sheet 16, one end of the wrapping sheet 16 and the other end of the wrapping sheet 16 may be separated from each other on the surface of the second base material 13 opposite to the surface on which the water absorption layer 12 is provided. .. For example, in FIG. 2, the wrapping sheet 16 is placed on the first base material 11, bent so as to wrap the side surface of the water absorption layer 12 and the side surface of the second base material 13, and the second base material. One end of the wrapping sheet 16 and the other end of the wrapping sheet 16 are arranged apart from each other on the surface opposite to the liquid absorbing surface (that is, the surface provided with the water absorbing layer 12) that directly absorbs the liquid of 13. ing. In this case, the wrapping sheet 16 covers the liquid absorbing surface and the side surface of the first base material 11, the side surface of the water absorbing layer 12, and the side surface of the second base material 13, and the water absorbing layer of the second base material 13. It covers a part of the surface opposite to the surface on which the 12 is provided.
　本発明に係る吸水性シート１０においてラッピングシート１６は必須の構成ではないが、本発明に係る吸水性シート１０にラッピングシート１６がかような構成で備えられることにより、粒子状吸水剤１４の吸水性シート１０からの脱落を抑制することができる。 Although the wrapping sheet 16 is not an essential configuration in the water absorbing sheet 10 according to the present invention, the water absorbing sheet 10 according to the present invention is provided with the wrapping sheet 16 in such a configuration so that the particulate water absorbing agent 14 absorbs water. It is possible to prevent the sex sheet 10 from falling off.
　よって、本発明の一実施形態に係る吸水性シート１０は、少なくとも、第１の基材１１の表面に配置させるラッピングシート１６を有することが好ましい。なお、本明細書中、上述のように、ラッピングシート１６を有している場合でも、第１の基材１１が液を直接的に吸収する吸液面を形成するものとするが、例えば、ラッピングシート１６を有する吸水性シート１０においては、ラッピングシート１６が液を直接的に吸収する吸液面を形成するとした場合には、以下のように換言できる；第１の基材と、第２の基材と、前記第１の基材と、前記第２の基材との間に位置する吸水層と、前記第１の基材の表面に配置させるラッピングシートと、を有する、吸水性シートであって、前記吸水層が粒子状吸水剤を含み、前記ラッピングシートの表面が、液を直接的に吸収する吸液面を形成し、前記第２の基材の厚みに対する、前記第１の基材の厚みの比（第１の基材の厚み（ｍｍ）／第２の基材の厚み（ｍｍ））が、１．５以上１４未満である。 Therefore, it is preferable that the water-absorbent sheet 10 according to the embodiment of the present invention has at least a wrapping sheet 16 to be arranged on the surface of the first base material 11. In the present specification, as described above, even when the wrapping sheet 16 is provided, the first base material 11 forms a liquid absorbing surface that directly absorbs the liquid. In the water-absorbent sheet 10 having the wrapping sheet 16, if the wrapping sheet 16 forms a liquid-absorbing surface that directly absorbs the liquid, it can be paraphrased as follows; A water-absorbent sheet having a base material, a water-absorbent layer located between the first base material and the second base material, and a wrapping sheet arranged on the surface of the first base material. The water absorbing layer contains a particulate water absorbing agent, the surface of the wrapping sheet forms a liquid absorbing surface that directly absorbs the liquid, and the first base material has a thickness relative to the thickness of the second base material. The ratio of the thickness of the base material (thickness of the first base material (mm) / thickness of the second base material (mm)) is 1.5 or more and less than 14.
　ラッピングシート１６を各基材１１，１３に固着させる方法としては、例えば、接着剤を使用すればよい。 As a method of fixing the wrapping sheet 16 to the base materials 11 and 13, for example, an adhesive may be used.
　本発明において、第１の基材１１と、吸水層１２における粒子状吸水剤１４とは、直接または接着剤を介して接することが好ましく、および／または、第２の基材１３と、吸水層１２における粒子状吸水剤１４とは、直接または接着剤を介して接することが好ましい。このように、本発明の吸水性シートは、実質的に、第１の基材と；第２の基材と；第１の基材および第２の基材に挟まれている粒子状吸水剤と；粒子状吸水剤を第１の基材および第２の基材の少なくとも一方に固着する接着剤と；必要に応じこれらの一部または全部を包み込むラッピングシートと；のみからなる、シンプルな構成である（粒子状吸水剤に含まれうる本明細書で説明する添加剤等を含むことは排除されない）。より好ましい形態としては、第１の基材と；第２の基材と；第１の基材、第２の基材に挟まれている粒子状吸水剤と；粒子状吸水剤と第２の基材との間で粒子状吸水剤を第２の基材に固着する接着剤と；これらの全部を包み込むラッピングシートと；のみからなる、シンプルな構成である。すなわち、本発明の吸水性シートは、シンプルな構成であるにもかかわらず、特定戻り量が効果的に低減できるものである。 In the present invention, the first base material 11 and the particulate water absorbing agent 14 in the water absorbing layer 12 are preferably in contact with each other directly or via an adhesive, and / or the second base material 13 and the water absorbing layer 13 are in contact with each other. It is preferable that the particulate water absorbing agent 14 in No. 12 is in contact with the water absorbing agent 14 directly or via an adhesive. As described above, the water-absorbent sheet of the present invention is substantially a particulate water-absorbing agent sandwiched between the first base material and the second base material; the first base material and the second base material. And; a simple configuration consisting of only an adhesive that adheres the particulate water absorbent to at least one of the first and second substrates; and a wrapping sheet that wraps some or all of these as needed. (It is not excluded that the particulate water-absorbing agent contains the additives and the like described in the present specification). More preferred embodiments include a first substrate; a second substrate; a first substrate, a particulate water absorbent sandwiched between the second substrates; a particulate water absorbent and a second substrate. It has a simple structure consisting only of an adhesive that adheres a particulate water-absorbing agent to the base material to the second base material; and a wrapping sheet that wraps all of them. That is, although the water-absorbent sheet of the present invention has a simple structure, the specific return amount can be effectively reduced.
　本発明において、第２の基材の厚み（ｍｍ）に対する第１の基材の厚み（ｍｍ）の比（第１の基材の厚み（ｍｍ）／第２の基材の厚み（ｍｍ））は、１．５以上１４未満である。第２の基材の厚み（ｍｍ）に対する第１の基材の厚み（ｍｍ）の比が１．５未満の場合、第１の基材の吸液面と、吸水層および第２の基材との距離が十分に確保されず、いったん吸水層および第２の基材へと達した液が逆戻りするおそれがある。また、第２の基材の厚み（ｍｍ）に対する第１の基材の厚み（ｍｍ）の比が１４以上の場合、第１の基材の吸液面と、吸水層とが離れていることにより、第１の基材の吸液面から吸収された液が吸水層に到達する前に、面方向の漏れが発生するおそれがある。 In the present invention, the ratio of the thickness (mm) of the first base material to the thickness (mm) of the second base material (thickness of the first base material (mm) / thickness of the second base material (mm)). Is 1.5 or more and less than 14. When the ratio of the thickness (mm) of the first base material to the thickness (mm) of the second base material is less than 1.5, the liquid absorption surface of the first base material, the water absorption layer, and the second base material The distance between the water absorption layer and the second base material may not be sufficiently secured, and the liquid once reaching the water absorption layer and the second base material may return. When the ratio of the thickness (mm) of the first base material to the thickness (mm) of the second base material is 14 or more, the liquid absorption surface of the first base material and the water absorption layer are separated. As a result, leakage in the surface direction may occur before the liquid absorbed from the liquid absorbing surface of the first base material reaches the water absorbing layer.
　第２の基材の厚み（ｍｍ）に対する第１の基材の厚み（ｍｍ）の比の下限は、好ましくは１．７以上であり、より好ましくは２．５以上であり、さらに好ましくは３．２以上であり、さらにより好ましくは３．４以上であり、特に好ましくは３．５以上であり、最も好ましくは３．６以上である。第２の基材の厚み（ｍｍ）に対する第１の基材の厚み（ｍｍ）の比の上限は、好ましくは１２以下であり、より好ましくは１０以下であり、さらに好ましくは９以下であり、さらにより好ましくは８以下である。第２の基材の厚み（ｍｍ）に対する第１の基材の厚み（ｍｍ）の比がかような範囲であることにより、逆戻りが有意に低減できる。 The lower limit of the ratio of the thickness (mm) of the first base material to the thickness (mm) of the second base material is preferably 1.7 or more, more preferably 2.5 or more, still more preferably 3. It is .2 or more, even more preferably 3.4 or more, particularly preferably 3.5 or more, and most preferably 3.6 or more. The upper limit of the ratio of the thickness (mm) of the first base material to the thickness (mm) of the second base material is preferably 12 or less, more preferably 10 or less, still more preferably 9 or less. Even more preferably, it is 8 or less. When the ratio of the thickness (mm) of the first base material to the thickness (mm) of the second base material is within such a range, the reversion can be significantly reduced.
　本発明の一実施形態に係る吸水性シートは、第２の基材の厚み（ｍｍ）に対する第１の基材の厚み（ｍｍ）の比は、１．５以上１４未満である。また、本発明の一実施形態に係る吸水性シートは、第２の基材の厚み（ｍｍ）に対する第１の基材の厚み（ｍｍ）の比は、１．７以上１４未満であるのが好ましく、３以上１２以下であるのがより好ましく、３．４以上１０以下であるのがさらに好ましい。 In the water-absorbent sheet according to the embodiment of the present invention, the ratio of the thickness (mm) of the first base material to the thickness (mm) of the second base material is 1.5 or more and less than 14. Further, in the water-absorbent sheet according to the embodiment of the present invention, the ratio of the thickness (mm) of the first base material to the thickness (mm) of the second base material is 1.7 or more and less than 14. It is preferably 3 or more and 12 or less, and more preferably 3.4 or more and 10 or less.
　本発明の一実施形態に係る吸水性シートは、第１の基材が低密度で嵩高い形態となりうるが、従来型の吸収性物品に用いられる吸収体よりも、薄型化が可能である。上記吸水性シートを、紙オムツに使用する場合、その厚さは、例えば４０％ＲＨ～５０％ＲＨにおいて、好ましくは１５ｍｍ以下、より好ましくは１０ｍｍ以下、さらにより好ましくは７ｍｍ以下、特に好ましくは５ｍｍ以下、最も好ましくは４ｍｍ以下である。一方、厚さの下限は、吸水性シートの強度および粒子状吸水剤の直径を鑑みると、好ましくは０．２ｍｍ以上、より好ましくは０．３ｍｍ以上、よりさらに好ましくは０．５ｍｍ以上である。本願の実施例で使用した吸水性シートの厚みは、２～５ｍｍであった。 The water-absorbent sheet according to the embodiment of the present invention may have a first base material having a low density and a bulky form, but can be made thinner than an absorber used for a conventional absorbent article. When the water-absorbent sheet is used for disposable diapers, the thickness thereof is, for example, 40% RH to 50% RH, preferably 15 mm or less, more preferably 10 mm or less, still more preferably 7 mm or less, and particularly preferably 5 mm. Below, it is most preferably 4 mm or less. On the other hand, the lower limit of the thickness is preferably 0.2 mm or more, more preferably 0.3 mm or more, still more preferably 0.5 mm or more, in consideration of the strength of the water absorbing sheet and the diameter of the particulate water absorbing agent. The thickness of the water-absorbent sheet used in the examples of the present application was 2 to 5 mm.
　なお、本願における第１の基材、第２の基材、ラッピングシート、吸水性シートの厚みは、ダイヤルシックネスゲージ　大型タイプ（厚み測定器）（株式会社　尾崎製作所製、型番：Ｊ－Ｂ、測定子：アンビル上下φ５０ｍｍ）を用いて測定した。測定点数は、測定対象のシートにおいて、異なる箇所を５点とし、各箇所について２回測定し、測定値は合計５点の平均値とした。厚み測定時は、測定対象のシートに圧力が出来るだけかからないよう、ハンドルからゆっくりと手を離し、厚みを測定した。具体的な手順としては、測定対象のシートの測定箇所に皺や歪みが生じないよう、厚みが一定の板の上に平らに貼り付け、その板を厚み測定器の下部測定子の上にセットする。次に、厚み測定器の上部測定子を測定対象のシートから２～３ｍｍの高さ位置まで近づけた後、ハンドルからゆっくりと手を離し、測定対象のシートと板を合わせた厚みを測定する。測定対象のシートの厚みは、式：Ｔ１＝Ｔ２－Ｔ０（Ｔ０：板の厚み（ｍｍ）、Ｔ１：測定対象のシートの厚み（ｍｍ）、Ｔ２：測定対象のシートおよび板の厚み（ｍｍ））によって定まる。 The thickness of the first base material, the second base material, the lapping sheet, and the water-absorbent sheet in the present application is a dial thickness gauge large type (thickness measuring instrument) (manufactured by Ozaki Seisakusho Co., Ltd., model number: JB, measurement). Child: Measured using an anvil top and bottom φ50 mm). The number of measurement points was 5 points at different points on the sheet to be measured, and the measurement was performed twice at each point, and the measured values were the average value of a total of 5 points. When measuring the thickness, the thickness was measured by slowly releasing the hand from the handle so that pressure was not applied to the sheet to be measured as much as possible. As a specific procedure, the sheet to be measured is pasted flat on a plate having a constant thickness so that wrinkles and distortion do not occur at the measurement location, and the plate is set on the lower stylus of the thickness measuring instrument. To do. Next, after bringing the upper stylus of the thickness measuring instrument close to a height position of 2 to 3 mm from the sheet to be measured, slowly release the hand from the handle to measure the combined thickness of the sheet and the plate to be measured. The thickness of the sheet to be measured is the formula: T1 = T2-T0 (T0: thickness of the plate (mm), T1: thickness of the sheet to be measured (mm), T2: thickness of the sheet to be measured and the plate (mm)). ).
　ここで、吸水性シートに含有される粒子状吸水剤の含有量は、好ましくは５０～４００ｇ／ｍ２であり、より好ましくは１００～３５０ｇ／ｍ２であり、さらに好ましくは１２５～２５０ｇ／ｍ２である。 Here, the content of the particulate water-absorbing agent contained in the water-absorbent sheet is preferably 50 to 400 g / m 2 , more preferably 100 to 350 g / m 2 , and even more preferably 125 to 250 g / m. It is 2.
　第１の基材の吸水層側の面（粒子状吸水剤が配置される面）において、粒子状吸水剤が含まれる領域の比率（以下、「粒子状吸水剤１４の存在領域の比率」とも称する）は、面積で７５％を超えることが好ましく、８０％を超えることがより好ましく、９０％を超えることがさらにより好ましい。また、第１の基材の吸水層側の面における粒子状吸水剤が含まれる領域の比率の上限としては、特に制限されないが、実用上、面積で９９．５％以下である。このような範囲で粒子状吸水剤が設けられることで、粒子状吸水剤がバランスよく配置され、戻り量の低減効果が一層発揮される。なお、第１の基材の吸水層側の面における粒子状吸水剤が含まれる領域の比率は、第２の基材の吸水層側の面（粒子状吸水剤が配置される面）における粒子状吸水剤が含まれる領域の比率と同様である。 On the surface of the first base material on the water absorbing layer side (the surface on which the particulate water absorbing agent is arranged), the ratio of the region containing the particulate water absorbing agent (hereinafter, also referred to as "the ratio of the region where the particulate water absorbing agent 14 exists"). The area is preferably more than 75%, more preferably more than 80%, and even more preferably more than 90%. Further, the upper limit of the ratio of the region containing the particulate water absorbing agent on the surface of the first base material on the water absorbing layer side is not particularly limited, but is practically 99.5% or less in terms of area. By providing the particulate water-absorbing agent in such a range, the particulate water-absorbing agent is arranged in a well-balanced manner, and the effect of reducing the amount of return is further exhibited. The ratio of the region containing the particulate water-absorbing agent on the surface of the first base material on the water-absorbing layer side is the particle on the surface of the second base material on the water-absorbing layer side (the surface on which the particulate water-absorbing agent is arranged). It is the same as the ratio of the region containing the water absorbing agent.
　ここで、第１の基材の吸水層側の面における粒子状吸水剤が含まれる領域の比率は、吸水性シートの製造時に粒子状吸水剤の散布領域を調整することにより制御することができる。 Here, the ratio of the region containing the particulate water-absorbing agent on the surface of the first base material on the water-absorbing layer side can be controlled by adjusting the spraying region of the particulate water-absorbing agent during the production of the water-absorbent sheet. ..
　また、作製した吸水性シートの断面をＸ線ＣＴ装置（ｉｎｓｐｅＸｉｏ　ＳＭＸ－１００ＣＴ）により撮影、解析することにより、第１の基材の吸水層側の面における粒子状吸水剤が含まれる領域の比率を算出することができる。具体的には、吸水性シートの断面を撮影し、第１の基材または第２の基材と吸水層との界面を、粒子状吸水剤が存在する領域と、粒子状吸水剤が存在しない領域とに分類し、それぞれの領域を合計し、その比を算出することにより粒子状吸水剤が含まれる領域の比率を算出することができる。なお、吸水性シートの短手方向の断面を３枚以上撮影し、粒子状吸水剤が含まれる領域の比率を算出し、それぞれの断面から得られた粒子状吸水剤が含まれる領域の比率を平均した値を「粒子状吸水剤が含まれる領域の比率」とする。 Further, by photographing and analyzing the cross section of the produced water-absorbent sheet with an X-ray CT apparatus (inspeXio SMX-100CT), the ratio of the region containing the particulate water-absorbing agent on the surface of the first base material on the water-absorbent layer side. Can be calculated. Specifically, the cross section of the water-absorbent sheet is photographed, and the interface between the first base material or the second base material and the water-absorbing layer is a region where the particulate water-absorbing agent is present and the particle-like water-absorbing agent is not present. The ratio of the region containing the particulate water absorbing agent can be calculated by classifying the regions into regions, summing each region, and calculating the ratio thereof. In addition, three or more cross sections of the water absorbing sheet in the lateral direction were photographed, the ratio of the region containing the particulate water absorbing agent was calculated, and the ratio of the region containing the particulate water absorbing agent obtained from each cross section was calculated. The average value is defined as the "ratio of regions containing the particulate water absorbent".
　吸水性シートにさらに通液性、拡散性、柔軟性などを付与するために、吸水性シートの表面（第１の基材の表面または後述のラッピングシートの表面）に適宜エンボス加工を施してもよい。エンボス加工を施す領域は、吸水性シート表面の全面でもよく、一部でもよい。連続したエンボス加工領域を、吸水性シートの長手方向に設けることにより、液を長手方向に容易に拡散させることができる。例えば、エンボス加工領域を、長手方向に連続して設けることにより、当該領域が、大量の液を流すための通路（液体搬送通路）の役割を果たす。なお、エンボス加工領域は直線状に設けても、曲線状に設けても、波型に設けてもよい。 Even if the surface of the water-absorbent sheet (the surface of the first base material or the surface of the wrapping sheet described later) is appropriately embossed in order to further impart liquid permeability, diffusibility, flexibility, etc. to the water-absorbent sheet. Good. The region to be embossed may be the entire surface of the water-absorbent sheet surface or a part thereof. By providing a continuous embossed region in the longitudinal direction of the water-absorbent sheet, the liquid can be easily diffused in the longitudinal direction. For example, by providing the embossed region continuously in the longitudinal direction, the region serves as a passage (liquid transport passage) for flowing a large amount of liquid. The embossed region may be provided linearly, curvedly, or corrugated.
　また、粒子状吸水剤は吸水性シートの全面に散布されていてもよく、一部に粒子状吸水剤の非存在領域が設けられていてもよい。すなわち、第１の基材と第２の基材との間の吸水層において、粒子状吸水剤が吸水層の全面に散布されていてもよく、吸水層の一部に粒子状吸水剤の非存在領域が設けられていてもよい。 Further, the particulate water absorbing agent may be sprayed on the entire surface of the water absorbing sheet, or a region where the particulate water absorbing agent does not exist may be provided in a part thereof. That is, in the water absorbing layer between the first base material and the second base material, the particulate water absorbing agent may be sprayed on the entire surface of the water absorbing layer, and the particulate water absorbing agent is not applied to a part of the water absorbing layer. An existing area may be provided.
　ここで、第１の基材と第２の基材との間の吸水層において、吸水層の一部に粒子状吸水剤の非存在領域が設けられている形態について説明する。吸水層の一部に粒子状吸水剤の非存在領域が設けられている形態としては、第１の基材と第２の基材との間の吸水層において、粒子状吸水剤が含まれる領域が、実質的に粒子状吸水剤を含まない間隙を隔てて配置されている状態である。吸水層の一部に粒子状吸水剤の非存在領域を設ける場合、粒子状吸水剤の非存在領域は、吸水性シートの長手方向に、チャネル状（筋状）に設けることが好ましい。このように、粒子状吸水剤の不存在領域を、長手方向に連続して設けることにより、当該領域が、大量の液を流すための通路（液体搬送通路）の役割を果たす。粒子状吸水剤の不存在領域は直線状に設けても、曲線状に設けても、波型に設けてもよい。 Here, in the water absorption layer between the first base material and the second base material, a form in which a non-existent region of the particulate water absorption agent is provided in a part of the water absorption layer will be described. In the form in which the non-existent region of the particulate water absorbing agent is provided in a part of the water absorbing layer, the region containing the particulate water absorbing agent in the water absorbing layer between the first base material and the second base material. However, it is in a state of being arranged with a gap substantially free of the particulate water absorbing agent. When a non-existent region of the particulate water-absorbing agent is provided in a part of the water-absorbing layer, the non-existent region of the particulate water-absorbing agent is preferably provided in a channel shape (streak shape) in the longitudinal direction of the water-absorbing sheet. In this way, by continuously providing the non-existent region of the particulate water absorbing agent in the longitudinal direction, the region serves as a passage (liquid transport passage) for flowing a large amount of liquid. The non-existent region of the particulate water absorbing agent may be provided linearly, curvedly, or corrugated.
　吸水層の一部に粒子状吸水剤の非存在領域が設けられている場合、第１の基材は、伸縮性を有するのが好ましく、第１の基材の伸び率が１０％以上であるのがより好ましい。一実施形態では、本発明の吸水性シートは、第１の基材と第２の基材との間の吸水層において、粒子状吸水剤が含まれる領域が、実質的に粒子状吸水剤を含まない間隙を隔てて配置され、第１の基材の伸び率が１０％以上である。例えば、粒子状吸水剤が第１の基材または第２の基材の全面に散布されるのではなく、粒子状吸水剤は、第１の基材または第２の基材の一部に粒子状吸水剤の非存在領域が設けられて散布される。これにより、粒子状吸水剤は、実質的に粒子状吸水剤を含まない間隙を隔てて配置される。 When a region in which the particulate water absorbing agent does not exist is provided in a part of the water absorbing layer, the first base material preferably has elasticity, and the elongation rate of the first base material is 10% or more. Is more preferable. In one embodiment, in the water-absorbing sheet of the present invention, in the water-absorbing layer between the first base material and the second base material, the region containing the particulate water-absorbing agent is substantially a particulate water-absorbing agent. It is arranged with a gap not included, and the elongation rate of the first base material is 10% or more. For example, instead of the particulate water absorbent being sprayed over the entire surface of the first or second substrate, the particulate water absorbent is particles on a portion of the first or second substrate. A non-existent area of the water absorbing agent is provided and sprayed. As a result, the particulate water-absorbing agent is arranged with a gap substantially free of the particulate water-absorbing agent.
　従来の吸水性シートの構成では、吸液した吸水性樹脂粒子が膨潤することによって、吸水性樹脂粒子の上下シートに対する固定が弱まり、吸水性樹脂粒子がシート内で移動してしまう場合がある。そうすると、シート内で吸水性樹脂粒子の偏りが生じ、吸水性シートの形状が崩れる。この場合、吸水性シートの液吸収性に偏りが生じることになり、漏れの原因となる。場合によっては、吸水性樹脂粒子がシート内から外部へ脱落してしまうこともある。 In the conventional water-absorbent sheet configuration, the water-absorbent resin particles swell, which weakens the fixation of the water-absorbent resin particles to the upper and lower sheets, and the water-absorbent resin particles may move in the sheet. Then, the water-absorbent resin particles are biased in the sheet, and the shape of the water-absorbent sheet is deformed. In this case, the liquid absorbency of the water-absorbent sheet becomes uneven, which causes leakage. In some cases, the water-absorbent resin particles may fall off from the inside of the sheet to the outside.
　本発明の吸水性シートの一実施形態において、第１の基材の伸び率が１０％以上であり、吸水層の一部に粒子状吸水剤の非存在領域が設けられている場合、特定戻り量が効果的に低減できるだけでなく、液吸収後であってもシート形状が保持される（シートの保形性が高い）。 In one embodiment of the water-absorbing sheet of the present invention, when the elongation rate of the first base material is 10% or more and a region in which the particulate water-absorbing agent does not exist is provided in a part of the water-absorbing layer, the specific return Not only can the amount be effectively reduced, but the sheet shape is retained even after liquid absorption (the sheet has high shape retention).
　以下では、図３に基づいて、第１の基材と第２の基材との間の吸水層において、粒子状吸水剤が含まれる領域が、実質的に粒子状吸水剤を含まない間隙を隔てて配置され、第１の基材の伸び率が１０％以上である形態について説明する。図３は、本発明の他の実施形態に係る吸水性シート１０の、断面を表す模式図である。図３には、吸水性シート１０の３つの形態（（ａ）～（ｃ））が示されている。図３（ａ）～（ｃ）において、矢印は、吸収される液が導入される方向を示している。第１の基材１１は、吸水層１２に対して吸収される液（吸液される液）が導入される側に位置する。すなわち、第１の基材１１は、液体の排出側（例えば紙オムツでは肌側）に配置される。第１の基材１１と第２の基材１３との間に吸水層１２が配置される。 In the following, based on FIG. 3, in the water absorbing layer between the first base material and the second base material, the region containing the particulate water absorbing agent has a gap substantially free of the particulate water absorbing agent. A form in which the first base material is arranged at a distance and the elongation rate of the first base material is 10% or more will be described. FIG. 3 is a schematic view showing a cross section of the water-absorbent sheet 10 according to another embodiment of the present invention. FIG. 3 shows three forms ((a) to (c)) of the water-absorbent sheet 10. In FIGS. 3A to 3C, the arrows indicate the direction in which the absorbed liquid is introduced. The first base material 11 is located on the side where the liquid absorbed by the water absorbing layer 12 (the liquid to be absorbed) is introduced. That is, the first base material 11 is arranged on the liquid discharge side (for example, the skin side in the case of paper diapers). The water absorption layer 12 is arranged between the first base material 11 and the second base material 13.
　図３（ａ）～（ｃ）において、吸水層１２に粒子状吸水剤１４が含まれる。図３（ａ）～（ｃ）の形態においては、吸水層１２は、第１の基材１１および第２の基材１３の間に粒子状吸水剤１４が存在している状態を示す。一部の粒子状吸水剤１４は各基材１１，１３から脱離していてもよい。粒子状吸水剤１４（粒子状吸水剤１４が含まれる領域）は、実質的に粒子状吸水剤１４を含まない間隙１５を隔てて配置されている。したがって、吸水「層」とは、シートのような連続体だけを指すのではなく、第１の基材１１および第２の基材１３間に一定の厚さと長さとをもって存在するものであればいずれの形態であってもよい。例えば、吸水層１２は、第１の基材１１と第２の基材１３との間に、一定の厚さと長さとを有して断続的に存在していてもよい。基材１１、及び／又は、１３に粒子状吸水剤１４を固着させる場合、例えば、接着剤を使用すればよい。接着剤を用いて吸水性シートを製造する方法については、〔３．〕にて詳述する。 In FIGS. 3A to 3C, the water absorbing layer 12 contains the particulate water absorbing agent 14. In the form of FIGS. 3A to 3C, the water absorbing layer 12 shows a state in which the particulate water absorbing agent 14 is present between the first base material 11 and the second base material 13. A part of the particulate water absorbing agent 14 may be detached from each of the base materials 11 and 13. The particulate water-absorbing agent 14 (the region containing the particulate water-absorbing agent 14) is arranged with a gap 15 that does not substantially contain the particulate water-absorbing agent 14. Therefore, the water-absorbing "layer" does not mean only a continuum such as a sheet, but if it exists between the first base material 11 and the second base material 13 with a constant thickness and length. It may be in any form. For example, the water absorption layer 12 may be intermittently present between the first base material 11 and the second base material 13 with a constant thickness and length. When the particulate water absorbing agent 14 is fixed to the base material 11 and / or 13, for example, an adhesive may be used. For the method of producing a water-absorbent sheet using an adhesive, refer to [3. ] Will be described in detail.
　ここで、図３（ａ）では、間隙１５が、第１の基材１１と第２の基材１３との間に形成されているが、本発明における間隙１５としては、図３（ｂ）および図３（ｃ）の形態も含まれる。図３（ｂ）では、第１の基材１１と第２の基材１３とが接することにより粒子状吸水剤１４が含まれる領域が隔たれている。第１の基材と第２の基材が接触しているが、通液路が維持されているので間隙とみなす。また、吸水層１２に第１の基材１１（場合によっては第１の基材１１と第２の基材１３と）が入り込むことにより、吸水層１２が隔てられるため、当該形態において吸水層１２は断続的に存在する。図３（ｃ）では、第１の基材１１の端部と第２の基材１３の端部とを重ね合わすことにより、吸水性シート１０の端部が第１の基材１１と第２の基材１３とにより閉じられている。この場合においても、吸水層１２の端部において第１の基材１１（場合によっては第１の基材１１と第２の基材１３と）が入り込むことにより、吸水層１２の端部において、吸水層１２が存在しない状態となる。 Here, in FIG. 3A, the gap 15 is formed between the first base material 11 and the second base material 13, but the gap 15 in the present invention is shown in FIG. 3B. And the form of FIG. 3 (c) is also included. In FIG. 3B, the region containing the particulate water absorbing agent 14 is separated by the contact between the first base material 11 and the second base material 13. Although the first base material and the second base material are in contact with each other, it is regarded as a gap because the liquid passage is maintained. Further, since the water absorption layer 12 is separated by the first base material 11 (in some cases, the first base material 11 and the second base material 13) entering the water absorption layer 12, the water absorption layer 12 in the present embodiment. Exists intermittently. In FIG. 3C, the end portion of the first base material 11 and the end portion of the second base material 13 are overlapped so that the end portion of the water-absorbent sheet 10 becomes the first base material 11 and the second base material 11. It is closed by the base material 13 of the above. Also in this case, the first base material 11 (in some cases, the first base material 11 and the second base material 13) enters at the end portion of the water absorption layer 12, so that the end portion of the water absorption layer 12 The water absorption layer 12 does not exist.
　第１の基材１１内には、粒子状吸水剤１４が存在してもよい。第１の基材１１内の粒子状吸水剤１４としては、例えば、第１の基材１１に接触した（もしくは、固着させた）粒子状吸水剤１４や、第２の基材１３に接触した（もしくは、固着させた）粒子状吸水剤１４が脱離して、第１の基材１１内に捕捉された粒子状吸水剤１４であってもよい。第１の基材１１内に粒子状吸水剤１４が存在する場合、第１の基材１１中の粒子状吸水剤１４の含有割合は、吸水性シート１０全体に含まれる粒子状吸水剤１４に対して、好ましくは５％以上であり、より好ましくは１０％以上であり、さらに好ましくは２０％以上であり、さらにより好ましくは３０％以上である。なお、上限は特に制限されないが、好ましい順に、９０％以下、７０％以下、５０％以下である。なお、本明細書中、吸水性シート１０全体に含まれる粒子状吸水剤１４に対する第１の基材１１中の粒子状吸水剤１４の含有割合は、後述の実施例の方法により算出される。 The particulate water absorbing agent 14 may be present in the first base material 11. The particulate water absorbing agent 14 in the first base material 11 is, for example, in contact with the particulate water absorbing agent 14 that has come into contact with (or has been fixed to) the first base material 11 or the second base material 13. The particulate water-absorbing agent 14 (or fixed) may be desorbed and captured in the first base material 11. When the particulate water absorbing agent 14 is present in the first base material 11, the content ratio of the particulate water absorbing agent 14 in the first base material 11 is the particle water absorbing agent 14 contained in the entire water absorbing sheet 10. On the other hand, it is preferably 5% or more, more preferably 10% or more, still more preferably 20% or more, and even more preferably 30% or more. The upper limit is not particularly limited, but is 90% or less, 70% or less, and 50% or less in the preferred order. In the present specification, the content ratio of the particulate water absorbing agent 14 in the first base material 11 to the particulate water absorbing agent 14 contained in the entire water absorbing sheet 10 is calculated by the method of Examples described later.
　間隙１５の領域には粒子状吸水剤１４を散布、配置しないため、間隙１５の領域は、実質的に粒子状吸水剤１４を含有しない。この間隙１５の領域に粒子状吸水剤１４以外の添加剤等を含有してもよい。例えば、間隙１５は、第１の基材１１と第２の基材１３とが直接または接着剤を介して接することにより形成されていてもよい。第１の基材１１は伸縮性を有するため、第２の基材１３上に粒子状吸水剤１４が含まれる領域が存在する場合、第１の基材１１は粒子状吸水剤１４が含まれる領域に追随して伸縮する。よって、第１の基材１１は、粒子状吸水剤１４が含まれる領域上で粒子状吸水剤１４が含まれる領域を覆うような形状となり、間隙１５上では、粒子状吸水剤１４が含まれる領域の上側面に沿った後、第２の基材１３に向けて沈み込む形状となる。 Since the particulate water absorbing agent 14 is not sprayed or arranged in the region of the gap 15, the region of the gap 15 does not substantially contain the particulate water absorbing agent 14. Additives other than the particulate water absorbing agent 14 may be contained in the region of the gap 15. For example, the gap 15 may be formed by contacting the first base material 11 and the second base material 13 directly or via an adhesive. Since the first base material 11 has elasticity, the first base material 11 contains the particulate water absorbing agent 14 when there is a region on the second base material 13 containing the particulate water absorbing agent 14. It expands and contracts according to the area. Therefore, the first base material 11 has a shape that covers the region containing the particulate water absorbing agent 14 on the region containing the particulate water absorbing agent 14, and contains the particulate water absorbing agent 14 on the gap 15. After being along the upper side surface of the region, the shape is such that it sinks toward the second base material 13.
　本発明の吸水性シートにおいて、間隙１５における第１の基材１１の吸液面から第２の基材１３の吸水層１２側の表面までの厚み（Ｌａ）に対する、粒子状吸水剤１４が含まれる領域における第１の基材１１の吸液面から第２の基材１３の吸水層１２側の表面までの厚み（Ｌｂ）の比（Ｌｂ／Ｌａ）が、１．０５以下であるのが好ましい。第１の基材１１は伸縮性を有するため、第１の基材１１が粒子状吸水剤１４と接する部分において、粒子状吸水剤１４が含まれる領域の形状（すなわち、第１の基材と接する粒子状吸水剤１４において第１の基材１１と接する側の粒子状吸水剤１４の形状）に追随した形状となる（すなわち、追随して伸縮する）。よって、第１の基材１１は粒子状吸水剤１４（粒子状吸水剤１４が含まれる領域）と密着することができ、これにより、第１の基材１１は粒子状吸水剤１４（粒子状吸水剤１４が含まれる領域）と一体化された状態となっている。この場合、Ｌａの厚みとＬｂの厚みとの差が小さく、よって、Ｌｂ／Ｌａが１．０５以下となる。この場合、粒子状吸水剤１４が含まれる領域の形状の保形性が高い。よって、粒子状吸水剤１４が膨潤した後であっても間隙１５の維持性が高く、逆戻りをより低減することができる。なお、Ｌｂ／Ｌａは、通常１以上となる。 In the water-absorbing sheet of the present invention, the particulate water-absorbing agent 14 is contained with respect to the thickness (La) from the liquid-absorbing surface of the first base material 11 to the surface of the second base material 13 on the water-absorbing layer 12 side in the gap 15. The ratio (Lb / La) of the thickness (Lb) from the liquid absorbing surface of the first base material 11 to the surface of the second base material 13 on the water absorbing layer 12 side in the region is 1.05 or less. preferable. Since the first base material 11 has elasticity, the shape of the region containing the particulate water absorbing agent 14 (that is, the first base material) in the portion where the first base material 11 is in contact with the particulate water absorbing agent 14 The particle-like water-absorbing agent 14 in contact has a shape that follows (that is, the shape of the particle-like water-absorbing agent 14 on the side in contact with the first base material 11) (that is, expands and contracts accordingly). Therefore, the first base material 11 can be brought into close contact with the particulate water absorbing agent 14 (the region containing the particulate water absorbing agent 14), whereby the first base material 11 can be brought into close contact with the particulate water absorbing agent 14 (particulate). It is in a state of being integrated with the region (region containing the water absorbing agent 14). In this case, the difference between the thickness of La and the thickness of Lb is small, so that Lb / La is 1.05 or less. In this case, the shape retention of the shape of the region containing the particulate water absorbing agent 14 is high. Therefore, even after the particulate water absorbing agent 14 has swelled, the maintainability of the gap 15 is high, and the reversion can be further reduced. Lb / La is usually 1 or more.
　吸水性シート１０において、第２の基材１３上の一部に粒子状吸水剤１４の非存在領域が設けられることにより、間隙１５が形成される。間隙１５（すなわち、粒子状吸水剤１４の非存在領域）は、第１の基材１１の吸液面における一の方向に沿って連続して設けられることにより、通液路としての機能がより発揮できる。間隙１５が連続して設けられる形状としては、例えば、直線状、曲線状、または波型であってもよいが、これらの間隙１５が直線状で並列して設けられるのが好ましい。よって、吸水性シート１０において、粒子状吸水剤１４が含まれる領域および間隙１５は、第１の基材１１の吸液面における一の方向（液が吸液される方向と垂直の面方向）に沿って伸びた形状を有し、並列して配置されているのが好ましい。すなわち、粒子状吸水剤１４が含まれる領域が、筋状（縞状）に並んだ状態とされる。これにより、間隙１５も縞状に形成されるため、粒子状吸水剤１４が膨潤した場合にも間隙１５が維持しやすく、結果として逆戻りをさらに低減できる。ここで、「一の方向」とは、厚み方向を除く、第１の基材１１の吸液面における面方向に平行ないずれかの方向、すなわち、第１の基材１１の吸液面における長手方向、短手方向、またはこれらの方向に対して傾斜した方向のいずれでもよい。間隙１５の役割と、粒子状吸水剤１４の役割とのバランスの観点から、吸水性シート１０において、粒子状吸水剤１４が含まれる領域および間隙１５は、第１の基材１１の吸液面における長手方向に沿って伸びた形状を有し、並列して配置されているのが好ましい。 In the water-absorbent sheet 10, a gap 15 is formed by providing a non-existent region of the particulate water-absorbing agent 14 on a part of the second base material 13. The gap 15 (that is, the non-existent region of the particulate water absorbing agent 14) is continuously provided along one direction on the liquid absorbing surface of the first base material 11, so that the function as a liquid passing path is further enhanced. Can be demonstrated. The shape in which the gaps 15 are continuously provided may be, for example, linear, curved, or corrugated, but it is preferable that the gaps 15 are linearly provided in parallel. Therefore, in the water-absorbent sheet 10, the region and the gap 15 containing the particulate water-absorbing agent 14 are in one direction on the liquid-absorbing surface of the first base material 11 (the plane direction perpendicular to the direction in which the liquid is absorbed). It is preferable that it has a shape extending along the above and is arranged in parallel. That is, the regions containing the particulate water absorbing agent 14 are arranged in a streak (striped) pattern. As a result, the gaps 15 are also formed in stripes, so that the gaps 15 can be easily maintained even when the particulate water absorbing agent 14 swells, and as a result, reversion can be further reduced. Here, the "one direction" is any direction parallel to the surface direction on the liquid absorbing surface of the first base material 11, excluding the thickness direction, that is, on the liquid absorbing surface of the first base material 11. It may be in the longitudinal direction, the lateral direction, or the direction inclined with respect to these directions. From the viewpoint of the balance between the role of the gap 15 and the role of the particulate water absorbing agent 14, in the water absorbing sheet 10, the region containing the particulate water absorbing agent 14 and the gap 15 are the liquid absorbing surfaces of the first base material 11. It is preferable that the particles have a shape extending along the longitudinal direction and are arranged in parallel.
　第１の基材１１の吸水層１２側の面（粒子状吸水剤１４が配置される面）において、粒子状吸水剤１４が含まれる領域の比率は、面積で９０％以下であることが好ましく、８０％以下であることがより好ましく、７５％以下であることがさらにより好ましい。また、第１の基材１１の吸水層１２側の面における粒子状吸水剤１４が含まれる領域の比率は、面積で１０％以上であることが好ましく、２０％以上であることがより好ましい。このような範囲で粒子状吸水剤１４が設けられることで、間隙１５の役割と、粒子状吸水剤１４の役割とのバランスが適当となり、戻り量の低減効果が一層発揮される。なお、第１の基材１１の吸水層１２側の面における粒子状吸水剤１４が含まれる領域の比率は、第２の基材１３の吸水層１２側の面（粒子状吸水剤１４が配置される面）における粒子状吸水剤１４が含まれる領域の比率と同様である。 On the surface of the first base material 11 on the water absorbing layer 12 side (the surface on which the particulate water absorbing agent 14 is arranged), the ratio of the region containing the particulate water absorbing agent 14 is preferably 90% or less in terms of area. , 80% or less, and even more preferably 75% or less. Further, the ratio of the region containing the particulate water absorbing agent 14 on the surface of the first base material 11 on the water absorbing layer 12 side is preferably 10% or more, more preferably 20% or more in terms of area. By providing the particulate water absorbing agent 14 in such a range, the role of the gap 15 and the role of the particulate water absorbing agent 14 become appropriate, and the effect of reducing the amount of return is further exhibited. The ratio of the region containing the particulate water absorbing agent 14 on the surface of the first base material 11 on the water absorbing layer 12 side is the surface of the second base material 13 on the water absorbing layer 12 side (the particulate water absorbing agent 14 is arranged). It is the same as the ratio of the region containing the particulate water absorbing agent 14 on the surface).
　吸水性シート１０は、ラッピングシート１６を有する。ラッピングシート１６は、第１の基材１１と第２の基材１３の間で粒子状吸水剤１４が担持された構造物である吸水性シート１０の形状を保持する目的、第１の基材１１と第２の基材１３との間で担持された粒子状吸水剤１４が、吸収体（吸水性シート１０）からこぼれ落ちない（脱落しない）ようにする目的、粒子状吸水剤１４が第１の基材１１を透過し、第１の基材１１の外部表面（液が直接接触する面）に移行した場合、粒子状吸水剤１４が皮膚に直接接触しないようにする目的がある。ラッピングシート１６を有しない場合、例えば、各基材１１，１３同士を接着することで封止（シーリング）する方法、第１の基材１１の表面処理により、第１の基材１１の外部表面への移行を抑制する方法等がある。本願の効果を維持しつつ吸水性シート１０から粒子状吸水剤１４が脱落しない方法として、ラッピングシート１６を有することが好ましい。ラッピングシート１６の構成は、図１および図２で述べたため省略する。 The water-absorbent sheet 10 has a wrapping sheet 16. The wrapping sheet 16 is a first base material for the purpose of maintaining the shape of the water absorbing sheet 10, which is a structure in which the particulate water absorbing agent 14 is supported between the first base material 11 and the second base material 13. For the purpose of preventing the particulate water absorbing agent 14 supported between the 11 and the second base material 13 from spilling (not falling off) from the absorber (water absorbing sheet 10), the particulate water absorbing agent 14 is the first. The purpose is to prevent the particulate water absorbent 14 from coming into direct contact with the skin when it permeates through the base material 11 and migrates to the outer surface (the surface with which the liquid comes into direct contact) of the first base material 11. When the wrapping sheet 16 is not provided, for example, by a method of sealing by adhering the base materials 11 and 13 to each other, and by surface treatment of the first base material 11, the outer surface of the first base material 11 is formed. There is a method of suppressing the transition to. It is preferable to have the wrapping sheet 16 as a method of preventing the particulate water absorbing agent 14 from falling off from the water absorbing sheet 10 while maintaining the effect of the present application. The configuration of the wrapping sheet 16 is omitted because it has been described with reference to FIGS. 1 and 2.
　よって、本発明の吸水性シート１０は、少なくとも、第１の基材１１の表面（すなわち、第１の基材１１の吸液面上）に配置させるラッピングシート１６を有することが好ましい。なお、本明細書中、上述のように、ラッピングシート１６を有している場合でも、第１の基材１１が液を直接的に吸収する吸液面を形成するものとするが、例えば、ラッピングシート１６を有する吸水性シートにおいては、ラッピングシート１６が液を直接的に吸収する吸液面を形成するとした場合には、以下のように換言できる；第１の基材と、第２の基材と、前記第１の基材と、前記第２の基材との間に位置する吸水層と、前記第１の基材の表面に配置させるラッピングシートと、を有する、吸水性シートであって、前記吸水層は、粒子状吸水剤を含み、前記粒子状吸水剤が含まれる領域が、実質的に前記粒子状吸水剤を含まない間隙を隔てて配置され、前記ラッピングシートの表面が、液を直接的に吸収する吸液面を形成し、前記第２の基材の厚みに対する、前記第１の基材の厚みの比（第１の基材の厚み（ｍｍ）／第２の基材の厚み（ｍｍ））が、１．５以上１４未満であり、前記第１の基材は、伸び率が１０％以上である。 Therefore, it is preferable that the water-absorbent sheet 10 of the present invention has at least a wrapping sheet 16 to be arranged on the surface of the first base material 11 (that is, on the liquid-absorbing surface of the first base material 11). In the present specification, as described above, even when the wrapping sheet 16 is provided, the first base material 11 forms a water absorbing surface that directly absorbs the liquid. In the water-absorbent sheet having the wrapping sheet 16, if the wrapping sheet 16 forms a liquid-absorbing surface that directly absorbs the liquid, it can be paraphrased as follows; A water-absorbent sheet having a base material, a water-absorbent layer located between the first base material and the second base material, and a wrapping sheet arranged on the surface of the first base material. The water-absorbing layer contains the particulate water-absorbing agent, and the region containing the particulate water-absorbing agent is arranged with a gap substantially free of the particulate water-absorbing agent so that the surface of the wrapping sheet is formed. , A liquid absorption surface that directly absorbs the liquid is formed, and the ratio of the thickness of the first base material to the thickness of the second base material (thickness of the first base material (mm) / second The thickness (mm) of the base material is 1.5 or more and less than 14, and the first base material has an elongation rate of 10% or more.
　本発明の吸水性シート１０は、第１の基材１１と、吸水層１２における粒子状吸水剤１４とは、直接または接着剤を介して接することが好ましく、および／または、第２の基材１３と、吸水層１２における粒子状吸水剤１４とは、直接または接着剤を介して接することが好ましい。このように、本発明の吸水性シートは、実質的に、第１の基材と；第２の基材と；第１の基材、第２の基材に挟まれている粒子状吸水剤と；粒子状吸水剤を第１の基材および第２の基材の少なくとも一方に固着する接着剤と；必要に応じこれらの一部または全部を包み込むラッピングシートと；のみからなる、シンプルな構成である（粒子状吸水剤に含まれうる本明細書で説明する添加剤等を含むことは排除されない）。より好ましい形態としては、第１の基材と；第２の基材と；第１の基材、第２の基材に挟まれている粒子状吸水剤と；粒子状吸水剤と第２の基材との間で粒子状吸水剤を第２の基材に固着する接着剤と；これらの全部を包み込むラッピングシートと；のみからなる、シンプルな構成である。すなわち、本発明の吸水性シートは、シンプルな構成であるにもかかわらず、特定戻り量が効果的に低減できるものである。 In the water-absorbing sheet 10 of the present invention, the first base material 11 and the particulate water-absorbing agent 14 in the water-absorbing layer 12 are preferably in contact with each other directly or via an adhesive, and / or the second base material. It is preferable that 13 and the particulate water absorbing agent 14 in the water absorbing layer 12 are in contact with each other directly or via an adhesive. As described above, the water-absorbent sheet of the present invention is substantially a particulate water-absorbing agent sandwiched between a first base material, a second base material, and a first base material and a second base material. And; a simple configuration consisting of only an adhesive that adheres the particulate water absorbent to at least one of the first and second substrates; and a wrapping sheet that wraps some or all of these as needed. (It is not excluded that the particulate water-absorbing agent contains the additives and the like described in the present specification). More preferred embodiments include a first substrate; a second substrate; a first substrate, a particulate water absorbent sandwiched between the second substrates; a particulate water absorbent and a second substrate. It has a simple structure consisting only of an adhesive that adheres a particulate water-absorbing agent to the base material to the second base material; and a wrapping sheet that wraps all of them. That is, although the water-absorbent sheet of the present invention has a simple structure, the specific return amount can be effectively reduced.
　本発明において、第１の基材の伸び率は、１０％以上であり、好ましくは１５％以上であり、より好ましくは１７％以上であり、さらに好ましくは２０％以上であり、さらにより好ましくは２２％以上である。第１の基材の伸び率の上限は、特に制限されないが、６０％以下であるのが好ましい。第１の基材の伸び率がかような範囲であることにより、第１の基材が粒子状吸水剤の形状に追随しやすくなり、結果として吸水性シートの保形性がさらに高まり、逆戻り量をさらに低減できる。第１の基材の伸び率は、後述の実施例に記載の方法で測定された値を採用する。本明細書中、「不織布（第１の基材）の伸び率」としては、最も伸張する方向で伸び率を測定した際の数値とする。また、第１の基材の伸び率は、嵩密度、目付量、材質、網目構造、製造工程条件などによって制御可能である。 In the present invention, the elongation rate of the first base material is 10% or more, preferably 15% or more, more preferably 17% or more, still more preferably 20% or more, still more preferably. It is 22% or more. The upper limit of the elongation rate of the first base material is not particularly limited, but is preferably 60% or less. When the elongation rate of the first base material is within such a range, the first base material can easily follow the shape of the particulate water absorbing agent, and as a result, the shape retention of the water absorbing sheet is further enhanced, and the water absorbing sheet reverts. The amount can be further reduced. As the elongation rate of the first base material, a value measured by the method described in Examples described later is adopted. In the present specification, the "elongation rate of the non-woven fabric (first base material)" is a numerical value when the elongation rate is measured in the direction of maximum elongation. Further, the elongation rate of the first base material can be controlled by the bulk density, the basis weight, the material, the mesh structure, the manufacturing process conditions, and the like.
　なお、本発明において、第１の基材の伸びる方向は、厚み方向を除く、第１の基材の面方向に平行ないずれかの一方向が伸びればよく、特に制限されない。例えば、長方形の吸水性シートであれば、シート平面の長辺方向、短辺方向、対角線方向など、あらゆる角度の方向からいずれか一方向が、上記範囲の伸び率で伸びればよい。正方形、楕円形、円形の吸水性シートであった場合でも同様である。好ましくは、あらゆる方向（等方的）から伸びることができる基材である。 In the present invention, the extending direction of the first base material is not particularly limited as long as it extends in any one direction parallel to the surface direction of the first base material, excluding the thickness direction. For example, in the case of a rectangular water-absorbent sheet, any one direction from any angle direction such as the long side direction, the short side direction, and the diagonal direction of the sheet plane may be stretched at the elongation rate in the above range. The same applies to the case of a square, oval, or circular water-absorbent sheet. Preferably, it is a substrate that can extend from all directions (isotropic).
　本発明において、吸水性シート１０にさらに通液性、拡散性、柔軟性などを付与するために、第１の基材１１の表面に起毛加工を施してもよい。すなわち、本発明の一実施形態において、第１の基材１１は、液を直接的に吸収する吸液面と反対側の面、すなわち、吸水層１２が設けられた面（吸水層１２側の面）が起毛されている。本明細書中、「起毛」とは、表面の繊維が毛羽だった状態を意味する。 In the present invention, the surface of the first base material 11 may be brushed in order to further impart liquid permeability, diffusibility, flexibility, etc. to the water-absorbent sheet 10. That is, in one embodiment of the present invention, the first base material 11 is a surface opposite to the liquid absorbing surface that directly absorbs the liquid, that is, a surface provided with the water absorbing layer 12 (on the water absorbing layer 12 side). The surface) is brushed. As used herein, the term "raised" means a state in which the fibers on the surface are fluffed.
　本発明の吸水性シートの一実施形態において、第１の基材の吸水層側の面が起毛されている場合、特定戻り量が効果的に低減できるだけでなく、吸水性シートがいったん液を吸水した後において、吸水性シートからの粒子状吸水剤の脱落を効果的に抑制することができる。 In one embodiment of the water-absorbent sheet of the present invention, when the surface of the first base material on the water-absorbent layer side is brushed, not only the specific return amount can be effectively reduced, but also the water-absorbent sheet once absorbs the liquid. After that, it is possible to effectively prevent the particulate water-absorbing agent from falling off from the water-absorbing sheet.
　ここで、第１の基材１１の吸水層１２側の面が起毛されている形態について説明する。図４には、吸水層１２側の面が起毛された第１の基材１１を有する吸水性シートが示されている。図４に示すように、第１の基材１１は、吸水層１２側の面において、吸水層１２に向けて繊維が起毛している。第１の基材１１の起毛した繊維の一部は、粒子状吸水剤１４を超え、接着剤の塗布された第２の基材１３と接触して接着する。このため、粒子状吸水剤１４が吸水して膨潤した後も、第１の基材１１と第２の基材１３とは、第１の基材１１の起毛した繊維を介して接着し続けることができ、これにより、第１の基材１１と第２の基材１３と間の粒子状吸水剤１４を保持することができる。よって、第１の基材１１と第２の基材１３とが接着されることにより、吸水性シート１０が吸水した後も粒子状吸水剤１４が保持され、ゲル脱落率が低減できる。 Here, a form in which the surface of the first base material 11 on the water absorption layer 12 side is raised will be described. FIG. 4 shows a water-absorbent sheet having a first base material 11 whose surface on the water-absorbent layer 12 side is raised. As shown in FIG. 4, in the first base material 11, fibers are raised toward the water absorption layer 12 on the surface on the water absorption layer 12 side. A part of the raised fibers of the first base material 11 exceeds the particulate water absorbing agent 14 and comes into contact with and adheres to the second base material 13 to which the adhesive is applied. Therefore, even after the particulate water absorbing agent 14 absorbs water and swells, the first base material 11 and the second base material 13 continue to adhere to each other via the raised fibers of the first base material 11. This makes it possible to retain the particulate water absorbing agent 14 between the first base material 11 and the second base material 13. Therefore, by adhering the first base material 11 and the second base material 13, the particulate water absorbing agent 14 is retained even after the water absorbing sheet 10 absorbs water, and the gel dropout rate can be reduced.
　一実施形態において、第１の基材１１の吸水層１２側の面は起毛され、第１の基材は、接着剤によって粒子状吸水剤１４を担持しない。すなわち、第１の基材１１と、吸水層１２における粒子状吸水剤１４とは、直接接する。この場合、粒子状吸水剤１４は、第２の基材１３と接着剤により固着される。よって、一実施形態において、第１の基材１１と、吸水層１２における粒子状吸水剤１４とは、直接接することが好ましく、かつ、第２の基材１３と、吸水層１２における粒子状吸水剤１４とは、接着剤を介して接することが好ましい。 In one embodiment, the surface of the first base material 11 on the water absorption layer 12 side is brushed, and the first base material does not support the particulate water absorption agent 14 by the adhesive. That is, the first base material 11 and the particulate water absorbing agent 14 in the water absorbing layer 12 are in direct contact with each other. In this case, the particulate water absorbing agent 14 is fixed to the second base material 13 by an adhesive. Therefore, in one embodiment, it is preferable that the first base material 11 and the particulate water absorbing agent 14 in the water absorbing layer 12 are in direct contact with each other, and the second base material 13 and the particulate water absorbing agent in the water absorbing layer 12 are in direct contact with each other. It is preferable that the agent 14 is in contact with the agent 14 via an adhesive.
　第１の基材１１の吸水層１２側の面は起毛され、第１の基材は、接着剤によって粒子状吸水剤１４を担持しないことが好ましい理由としては、詳細は不明だが、実施例において、特定戻り量によりその効果が証明されている。すなわち、第１の基材１１の吸水層１２側の起毛された面には接着剤を塗布せず、第１の基材が接着剤によって粒子状吸水剤１４を担持しない形態は、第１の基材１１の吸水層１２側の起毛された面に接着剤を塗布し、第１の基材が接着剤によって粒子状吸水剤１４を担持した形態と比べて、特定戻り量が少なくなるので好ましい。 The reason why it is preferable that the surface of the first base material 11 on the water absorbing layer 12 side is brushed and the first base material does not support the particulate water absorbing agent 14 by the adhesive is unknown in detail, but in Examples. The effect is proved by the specific amount of return. That is, the first base material 11 has a form in which no adhesive is applied to the raised surface of the water absorbing layer 12 side of the first base material 11 and the first base material does not support the particulate water absorbing agent 14 by the adhesive. This is preferable because the specific return amount is smaller than in the form in which the adhesive is applied to the brushed surface of the base material 11 on the water absorbing layer 12 side and the first base material carries the particulate water absorbing agent 14 by the adhesive. ..
　ここで、第２の基材１３の吸水層１２側の面に塗布される接着剤、すなわち、第２の基材１３上の接着剤は、ホットメルト接着剤が好ましい。接着剤がホットメルト接着剤であることにより、第１の基材１１の起毛した繊維と第２の基材１３との接着が良好となり、吸水性シート１０が吸水した後も第１の基材１１と第２の基材１３とが接着し続け、第１の基材１１と第２の基材１３との間の粒子状吸水剤１４が保持される。 Here, the adhesive applied to the surface of the second base material 13 on the water absorption layer 12 side, that is, the adhesive on the second base material 13, is preferably a hot melt adhesive. Since the adhesive is a hot melt adhesive, the brushed fibers of the first base material 11 and the second base material 13 adhere well to each other, and even after the water-absorbent sheet 10 absorbs water, the first base material The 11 and the second base material 13 continue to adhere to each other, and the particulate water absorbing agent 14 between the first base material 11 and the second base material 13 is retained.
　吸水性シート１０は、ラッピングシート１６を有する。本発明に係る吸水性シート１０においてラッピングシート１６は必須の構成ではないが、吸水性シート１０において、吸水層１２側の面が起毛された第１の基材１１と、ラッピングシート１６とが備えられることにより、粒子状吸水剤１４の吸水性シート１０からの脱落を効果的に抑制することができる。ラッピングシート１６の構成は、上述したため省略する。 The water-absorbent sheet 10 has a wrapping sheet 16. Although the wrapping sheet 16 is not an essential configuration in the water-absorbent sheet 10 according to the present invention, the water-absorbent sheet 10 includes a first base material 11 having a brushed surface on the water-absorbent layer 12 side and a wrapping sheet 16. By doing so, it is possible to effectively suppress the particulate water absorbing agent 14 from falling off from the water absorbing sheet 10. The configuration of the wrapping sheet 16 will be omitted because it has been described above.
　よって、本発明の吸水性シート１０は、少なくとも、第１の基材１１の表面（すなわち、第１の基材１１の吸液面上）に配置させるラッピングシート１６を有することが好ましい。なお、本明細書中、上述のように、ラッピングシート１６を有している場合でも、第１の基材１１が液を直接的に吸収する吸液面を形成するものとするが、例えば、ラッピングシート１６を有する吸水性シートにおいては、ラッピングシート１６が液を直接的に吸収する吸液面を形成するとした場合には、以下のように換言できる；第１の基材と、第２の基材と、前記第１の基材と、前記第２の基材との間に位置する吸水層と、前記第１の基材の表面に配置させるラッピングシートと、を有する、吸水性シートであって、前記吸水層は、粒子状吸水剤を含み、前記ラッピングシートの表面が、液を直接的に吸収する吸液面を形成し、前記第２の基材の厚みに対する、前記第１の基材の厚みの比（第１の基材の厚み（ｍｍ）／第２の基材の厚み（ｍｍ））が、１．５以上１４未満であり、第１の基材１１は、吸水層１２が設けられた面（吸水層１２側の面）が起毛されている。 Therefore, it is preferable that the water-absorbent sheet 10 of the present invention has at least a wrapping sheet 16 to be arranged on the surface of the first base material 11 (that is, on the liquid-absorbing surface of the first base material 11). In the present specification, as described above, even when the wrapping sheet 16 is provided, the first base material 11 forms a water absorbing surface that directly absorbs the liquid. In the water-absorbent sheet having the wrapping sheet 16, if the wrapping sheet 16 forms a liquid-absorbing surface that directly absorbs the liquid, it can be paraphrased as follows; A water-absorbent sheet having a base material, a water-absorbent layer located between the first base material and the second base material, and a wrapping sheet arranged on the surface of the first base material. The water-absorbing layer contains a particulate water-absorbing agent, and the surface of the wrapping sheet forms a liquid-absorbing surface that directly absorbs the liquid, and the first one with respect to the thickness of the second base material. The ratio of the thickness of the base material (thickness of the first base material (mm) / thickness of the second base material (mm)) is 1.5 or more and less than 14, and the first base material 11 is a water absorption layer. The surface provided with 12 (the surface on the water absorption layer 12 side) is brushed.
　本発明の吸水性シート１０は、第１の基材１１と、吸水層１２における粒子状吸水剤１４とが、直接または接着剤を介して接することが好ましく、直接接するのがより好ましい。および／または、第２の基材１３と、吸水層１２における粒子状吸水剤１４とは、直接または接着剤を介して接することが好ましく、接着剤を介して接することがより好ましい。このように、本発明の吸水性シートは、実質的に、第１の基材と；第２の基材と；第１の基材、第２の基材に挟まれている粒子状吸水剤と；粒子状吸水剤を第１の基材および第２の基材の少なくとも一方に固着する接着剤と；必要に応じこれらの一部または全部を包み込むラッピングシートと；のみからなる、シンプルな構成である（粒子状吸水剤に含まれうる本明細書で説明する添加剤等を含むことは排除されない）。より好ましい形態としては、第１の基材と；第２の基材と；第１の基材、第２の基材に挟まれている粒子状吸水剤と；粒子状吸水剤と第２の基材との間で粒子状吸水剤を第２の基材に固着する接着剤と；これらの全部を包み込むラッピングシートと；のみからなる、シンプルな構成である。すなわち、本発明の吸水性シートは、シンプルな構成であるにもかかわらず、特定戻り量が効果的に低減できるものである。 In the water-absorbing sheet 10 of the present invention, the first base material 11 and the particulate water-absorbing agent 14 in the water-absorbing layer 12 are preferably in direct contact with each other or via an adhesive, and more preferably in direct contact with each other. And / or, the second base material 13 and the particulate water absorbing agent 14 in the water absorbing layer 12 are preferably in contact with each other directly or via an adhesive, and more preferably through an adhesive. As described above, the water-absorbent sheet of the present invention is substantially a particulate water-absorbing agent sandwiched between a first base material, a second base material, and a first base material and a second base material. And; a simple configuration consisting of only an adhesive that adheres the particulate water absorbent to at least one of the first and second substrates; and a wrapping sheet that wraps some or all of these as needed. (It is not excluded that the particulate water-absorbing agent contains the additives and the like described in the present specification). More preferred embodiments include a first substrate; a second substrate; a first substrate, a particulate water absorbent sandwiched between the second substrates; a particulate water absorbent and a second substrate. It has a simple structure consisting only of an adhesive that adheres a particulate water-absorbing agent to the base material to the second base material; and a wrapping sheet that wraps all of them. That is, although the water-absorbent sheet of the present invention has a simple structure, the specific return amount can be effectively reduced.
　吸水層１２側の面が起毛された第１の基材１１を有する吸水性シート１０においては、効果的に粒子状吸水剤１４の吸水性シート１０からの脱落を抑制することができるため、吸水性シート１０に含有される粒子状吸水剤１４の含有量を２００ｇ／ｍ２とすることができる。よって、吸水層１２側の面が起毛された第１の基材１１を有する吸水性シート１０においては、吸水性シート１０に含有される粒子状吸水剤１４の含有量は、好ましくは２００ｇ／ｍ２以上であり、２３０ｇ／ｍ２以上、２５０ｇ／ｍ２以上、２７０ｇ／ｍ２以上、２８０ｇ／ｍ２以上、３００ｇ／ｍ２以上の順に好ましい。この場合の吸水性シート１０に含有される粒子状吸水剤１４の含有量の上限は、特に制限されないが、吸水剤１４の保持の観点から、好ましくは３６０ｇ／ｍ２以下、より好ましくは３５０ｇ／ｍ２以下、さらに好ましくは３２５ｇ／ｍ２以下である。 In the water-absorbing sheet 10 having the first base material 11 whose surface on the water-absorbing layer 12 side is brushed, it is possible to effectively suppress the particulate water-absorbing agent 14 from falling off from the water-absorbing sheet 10, so that it absorbs water. The content of the particulate water absorbing agent 14 contained in the sex sheet 10 can be 200 g / m 2. Therefore, in the water-absorbent sheet 10 having the first base material 11 whose surface on the water-absorbent layer 12 side is raised, the content of the particulate water-absorbent agent 14 contained in the water-absorbent sheet 10 is preferably 200 g / m. 2 or more, preferably 230 g / m 2 or more, 250 g / m 2 or more, 270 g / m 2 or more, 280 g / m 2 or more, and 300 g / m 2 or more in this order. In this case, the upper limit of the content of the particulate water absorbing agent 14 contained in the water absorbing sheet 10 is not particularly limited, but from the viewpoint of retaining the water absorbing agent 14, it is preferably 360 g / m 2 or less, more preferably 350 g /. It is m 2 or less, more preferably 325 g / m 2 or less.
　また、吸水層１２側の面が起毛された第１の基材１１を有する吸水性シート１０においては、効果的に粒子状吸水剤１４の吸水性シート１０からの脱落を抑制することができるため、接着剤（好ましくはホットメルト接着剤）の量を低減することができる。よって、吸水層１２側の面が起毛された第１の基材１１を有する吸水性シート１０において、第２の基材１３上に散布される接着剤の含有量は、好ましくは１～５０ｇ／ｍ２であり、より好ましくは５～５０ｇ／ｍ２であり、さらにより好ましくは１０～４５ｇ／ｍ２であり、特に好ましくは１５～３０ｇ／ｍ２であり、最も好ましくは１５～２５ｇ／ｍ２である。 Further, in the water-absorbent sheet 10 having the first base material 11 whose surface on the water-absorbent layer 12 side is raised, it is possible to effectively prevent the particulate water-absorbent agent 14 from falling off from the water-absorbent sheet 10. , The amount of adhesive (preferably hot melt adhesive) can be reduced. Therefore, in the water-absorbent sheet 10 having the first base material 11 whose surface on the water-absorbent layer 12 side is brushed, the content of the adhesive sprayed on the second base material 13 is preferably 1 to 50 g / g. It is m 2 , more preferably 5 to 50 g / m 2 , even more preferably 10 to 45 g / m 2 , particularly preferably 15 to 30 g / m 2 , and most preferably 15 to 25 g / m. It is 2.
　一実施形態において、粒子状吸水剤と接着剤との質量比は、好ましくは８０：２０～９９：１であり、より好ましくは８５：１５～９８：２であり、さらに好ましくは９０：１０～９８：２であり、特に好ましくは９１：９～９７：３であり、最も好ましくは９２：８～９６：４である。第１の基材の吸水層側の面が起毛されていることにより、第１の基材の起毛した繊維と粒子状吸水剤とが絡まり、粒子状吸水剤が第１の基材に保持されるため、粒子状吸水剤に対する接着剤の量を減らすことができる。これにより、特定戻り量の低減効果がさらに発揮される。 In one embodiment, the mass ratio of the particulate water absorbent to the adhesive is preferably 80:20 to 99: 1, more preferably 85:15 to 98: 2, and even more preferably 90:10 to 90:10. It is 98: 2, particularly preferably 91: 9 to 97: 3, and most preferably 92: 8 to 96: 4. Since the surface of the first base material on the water absorption layer side is raised, the raised fibers of the first base material are entangled with the particulate water absorbing agent, and the particulate water absorbing agent is held by the first base material. Therefore, the amount of the adhesive to the particulate water absorbent can be reduced. As a result, the effect of reducing the specific return amount is further exhibited.
　吸水性シートにおいて、第１の基材の吸水層側の面が起毛されている場合、起毛されている面の起毛面積測定試験における起毛面積率は、５％以上であるのが好ましい。第１の基材の起毛されている面の起毛面積率は、５％以上、７％以上、１０％以上の順に好ましい。第１の基材の起毛されている面の起毛面積率の上限は、特に制限されないが、粒子状吸水剤の膨潤規制の観点から、好ましくは３０％以下、より好ましくは２８％以下、さらに好ましくは２５％以下である。本明細書中、起毛面積測定試験における起毛面積率は、後述の実施例に記載の方法により算出される。 In the water-absorbent sheet, when the surface of the first base material on the water-absorbing layer side is brushed, the brushed area ratio in the brushed area measurement test of the brushed surface is preferably 5% or more. The raised area ratio of the raised surface of the first base material is preferably 5% or more, 7% or more, and 10% or more in that order. The upper limit of the raised area ratio of the raised surface of the first base material is not particularly limited, but is preferably 30% or less, more preferably 28% or less, still more preferably, from the viewpoint of controlling the swelling of the particulate water absorbing agent. Is 25% or less. In the present specification, the raised area ratio in the raised area measurement test is calculated by the method described in Examples described later.
　本発明の吸水性シートの一実施形態において、第１の基材の吸水層側の面が起毛されている場合、特定戻り量が効果的に低減できるだけでなく、吸水性シートからの粒子状吸水剤の脱落を効果的に抑制することができる。例えば、本発明の実施例において算出される粒子状吸水剤の脱落率が、１０質量％以下であるのが好ましく、５質量％以下であるのがより好ましく、３質量％以下であるのがさらに好ましい。かような効果は、第１の基材の吸水層側の面が起毛されていることにより効果的に発現される。 In one embodiment of the water-absorbent sheet of the present invention, when the surface of the first base material on the water-absorbent layer side is brushed, not only the specific return amount can be effectively reduced, but also the particulate water absorption from the water-absorbent sheet can be effectively reduced. The dropout of the agent can be effectively suppressed. For example, the dropout rate of the particulate water absorbing agent calculated in the examples of the present invention is preferably 10% by mass or less, more preferably 5% by mass or less, and further preferably 3% by mass or less. preferable. Such an effect is effectively exhibited by raising the surface of the first base material on the water absorption layer side.
　本発明は、上述した実施形態に限定されるものではなく、特許請求の範囲内で種々改変することができる。 The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims.
　以下、吸水性シートを構成する各部材について詳細に説明する。 Hereinafter, each member constituting the water-absorbent sheet will be described in detail.
　［２－１．第１の基材］
　第１の基材は、吸液される液が導入される側に位置する、透水性シートである。なお、吸液される液とは水に限らず、尿、血液、汗、糞、廃液、湿気、蒸気、氷、水と有機溶媒および／または無機溶媒との混合物、雨水、地下水等であってもよく、水を含んでいれば特に制限されるものではない。好ましくは、尿、経血、汗、その他の体液を挙げることができる。 [2-1. First base material]
The first base material is a water-permeable sheet located on the side where the liquid to be absorbed is introduced. The liquid to be absorbed is not limited to water, but urine, blood, sweat, feces, waste liquid, moisture, vapor, ice, a mixture of water and an organic solvent and / or an inorganic solvent, rainwater, groundwater, etc. However, it is not particularly limited as long as it contains water. Preferably, urine, menstrual blood, sweat and other body fluids can be mentioned.
　第１の基材が、透水性シートであり、かつ、吸液される側に位置することで、本発明の効果である吸水性シートの性能（逆戻り量、面方向の漏れなど）を充分に発揮することができる。透水性シートにおける透水性は、透水係数（ＪＩＳ　Ａ１２１８：２００９）が１×１０－５ｃｍ／ｓｅｃ以上であることが好ましい。該透水係数は、より好ましくは１×１０－４ｃｍ／ｓｅｃ以上、さらにより好ましくは１×１０－３ｃｍ／ｓｅｃ以上、特に好ましくは１×１０－２ｃｍ／ｓｅｃ以上、最も好ましくは１×１０－１ｃｍ／ｓｅｃ以上である。本願の実施例で使用した第１の基材の透水係数は、１×１０－５ｃｍ／ｓｅｃ以上であった。 Since the first base material is a water-permeable sheet and is located on the side where the liquid is absorbed, the performance of the water-absorbent sheet (return amount, leakage in the plane direction, etc.), which is the effect of the present invention, can be sufficiently improved. Can be demonstrated. The water permeability of the water-permeable sheet preferably has a water permeability coefficient (JIS A1218: 2009) of 1 × 10-5 cm / sec or more. The hydraulic conductivity is more preferably 1 × 10 -4 cm / sec or more, even more preferably 1 × 10 -3 cm / sec or more, particularly preferably 1 × 10 −2 cm / sec or more, and most preferably 1 × It is 10 -1 cm / sec or more. The hydraulic conductivity of the first substrate used in the examples of the present application was 1 × 10-5 cm / sec or more.
　本発明において、第１の基材は、嵩密度が０．１ｇ／ｃｍ３以下であるのが好ましく、０．０８ｇ／ｃｍ３以下であるのがより好ましく、０．０５ｇ／ｃｍ３以下であるのがさらに好ましい。第１の基材の嵩密度は、好ましくは０．００１ｇ／ｃｍ３以上であり、より好ましくは０．００５ｇ／ｃｍ３以上であり、さらに好ましくは０．０１ｇ／ｃｍ３以上である。本明細書中、嵩密度とは、単位体積に対する質量であり、基材を高圧圧縮した場合（空隙を無くした場合）における密度ではなく、空隙の体積も含めた基材の体積より求めた密度である。第１の基材の嵩密度が０．１ｇ／ｃｍ３以下であるとは、第１の基材が軽いことを意味する。嵩高いとは、低い嵩密度で有意に厚いことを意味する。本発明では、第１の基材が嵩高いことにより、第１の基材の吸液面に接した吸収される液が、速やかに下層である吸水層および第２の基材へと流れ込み、第１の基材の吸液面に留まる液が低減できる。さらに、吸収された液が吸水層に到達する際には、液は面方向に拡散されており、ゆえに、液が多量に吸水層に導入されても、吸水層は局所でなく面方向に広がった液を吸収することになる。すなわち、嵩高い第１の基材は、吸水力が低く、通液力が高く、液拡散性が高い。これにより、吸水性シートにおける逆戻り量を低減することができる。第１の基材の吸液面の湿度が抑制でき、肌への不快感が低減できる。第１の基材の嵩密度は、好ましくは０．１ｇ／ｃｍ３以下である。なお、本明細書中、嵩密度は、後述の実施例で算出される値である。 In the present invention, the first substrate has a bulk density is preferably at 0.1 g / cm 3 or less, more preferably at 0.08 g / cm 3 or less, is 0.05 g / cm 3 or less Is even more preferable. The bulk density of the first substrate preferably being 0.001 g / cm 3 or more, more preferably 0.005 g / cm 3 or more, further preferably 0.01 g / cm 3 or more. In the present specification, the bulk density is the mass with respect to the unit volume, and is not the density when the base material is compressed under high pressure (when the voids are eliminated), but the density obtained from the volume of the base material including the volume of the voids. Is. When the bulk density of the first base material is 0.1 g / cm 3 or less, it means that the first base material is light. Bulky means low bulk density and significantly thicker. In the present invention, since the first base material is bulky, the absorbed liquid in contact with the liquid absorption surface of the first base material quickly flows into the lower water absorption layer and the second base material. The amount of liquid remaining on the liquid absorbing surface of the first base material can be reduced. Further, when the absorbed liquid reaches the water absorption layer, the liquid is diffused in the surface direction. Therefore, even if a large amount of the liquid is introduced into the water absorption layer, the water absorption layer spreads in the surface direction instead of locally. It will absorb the liquid. That is, the bulky first base material has low water absorption, high liquid permeability, and high liquid diffusivity. As a result, the amount of reversion in the water-absorbent sheet can be reduced. The humidity of the liquid absorbing surface of the first base material can be suppressed, and the discomfort to the skin can be reduced. The bulk density of the first base material is preferably 0.1 g / cm 3 or less. In this specification, the bulk density is a value calculated in Examples described later.
　本発明において、第１の基材は、目付量が３～８０ｇ／ｍ２であるのが好ましく、５～７０ｇ／ｍ２であるのがより好ましく１０～６０ｇ／ｍ２であるのがさらに好ましい。第１の基材の目付量がかような範囲であることにより、逆戻り量をさらに低減でき、また、第１の基材中に粒子状吸水剤を取り込みやすくなり、結果として吸水性シートの保形性がさらに高まる。 In the present invention, the first base material preferably has a basis weight of 3 to 80 g / m 2 , more preferably 5 to 70 g / m 2 , and even more preferably 10 to 60 g / m 2. .. When the basis weight of the first base material is within such a range, the amount of reversion can be further reduced, and the particulate water absorbing agent can be easily taken into the first base material, and as a result, the water absorbing sheet is retained. The shape is further enhanced.
　第１の基材の厚みは、例えば４０％ＲＨ～５０％ＲＨにおいて、好ましくは０．７ｍｍ以上、より好ましくは１．０ｍｍ以上、さらにより好ましくは１．２ｍｍ以上、特に好ましくは１．３ｍｍ以上、最も好ましくは１．４ｍｍ以上である。第１の基材の厚みの上限は、例えば４０％ＲＨ～５０％ＲＨにおいて、好ましくは５ｍｍ以下であり、より好ましくは４ｍｍ以下、さらにより好ましくは３ｍｍ以下、特に好ましくは２．５ｍｍ以下、最も好ましくは２ｍｍ以下である。第１の基材の厚みがかような範囲であることにより、第１の基材の吸液面と、吸水層および第２の基材との距離が十分に確保でき、いったん吸水層および第２の基材へと達した液が逆戻りするのを有意に低減でき、かつ面方向の漏れを低減することができる。 The thickness of the first substrate is, for example, 40% RH to 50% RH, preferably 0.7 mm or more, more preferably 1.0 mm or more, still more preferably 1.2 mm or more, and particularly preferably 1.3 mm or more. , Most preferably 1.4 mm or more. The upper limit of the thickness of the first base material is, for example, 40% RH to 50% RH, preferably 5 mm or less, more preferably 4 mm or less, still more preferably 3 mm or less, and particularly preferably 2.5 mm or less. It is preferably 2 mm or less. When the thickness of the first base material is within such a range, a sufficient distance between the liquid absorbing surface of the first base material and the water absorbing layer and the second base material can be sufficiently secured, and once the water absorbing layer and the second base material are used. It is possible to significantly reduce the reversion of the liquid that has reached the base material of No. 2 and reduce the leakage in the plane direction.
　第１の基材の厚み、嵩密度、目付量は、第１の基材を構成する材料、第１の基材の製法などによって制御することができ、これらのバランスで第１の基材の厚みや嵩密度が定まる。 The thickness, bulk density, and basis weight of the first base material can be controlled by the material constituting the first base material, the manufacturing method of the first base material, and the like. The thickness and bulk density are determined.
　第１の基材は、粒子状吸水剤の透過率（第１の基材に対する粒子状吸水剤の透過率）が、好ましくは４０質量％以上であり、より好ましくは５０質量％以上であり、さらに好ましくは、好ましい順に、６０質量％以上、７０質量％以上であり、特に好ましくは８０質量％以上、最も好ましくは９０質量％以上である。なお、透過率の上限は、特に制限されないが、好ましくは９７質量％以下である。第１の基材に対する粒子状吸水剤の透過率がかような範囲であることにより、第１の基材の吸水層と接する側において、粒子状吸水剤が第１の基材内に入り込みやすくなる。これにより、第１の基材中に含まれる水分を粒子状吸水剤が吸収することが可能となり、逆戻りがさらに低減される。なお、本明細書中、第１の基材に対する粒子状吸水剤の透過率は、第１の基材を透過する粒子状吸水剤の比率であり、第１の基材上に存在する粒状吸水剤が、後述する所定の条件でふるわれた場合における、第１の基材を通過した粒子状吸水剤の重量により求められ、具体的には後述の実施例に記載の方法で算出される値である。ここで、第１の基材の透過率は、第１の基材が不織布の場合は、第１の基材を構成する部材の性質、その表面状態、網目構造の複雑さ、繊維径、繊維間の融着状態、目付、厚み等を適宜調整することにより、所望の範囲に調整することができる。例えば、第１の基材が、後述のようにエアスルー不織布を用いるのであればエアスルー不織布の熱処理条件や繊維径及び密度を変更することによって透過率を調整することができる。 The first base material has a particulate water absorbing agent transmittance (permeability of the particulate water absorbing agent with respect to the first base material) of preferably 40% by mass or more, more preferably 50% by mass or more. More preferably, it is 60% by mass or more, 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more, in the order of preference. The upper limit of the transmittance is not particularly limited, but is preferably 97% by mass or less. Since the transmittance of the particulate water-absorbing agent with respect to the first base material is within such a range, the particulate water-absorbing agent easily enters the first base material on the side in contact with the water-absorbing layer of the first base material. Become. As a result, the water-absorbing agent in the form of particles can absorb the water contained in the first base material, and the reversion is further reduced. In the present specification, the transmittance of the particulate water-absorbing agent with respect to the first base material is the ratio of the particulate water-absorbing agent that permeates the first base material, and the granular water absorption existing on the first base material. A value determined by the weight of the particulate water-absorbing agent that has passed through the first substrate when the agent is shaken under predetermined conditions described later, and specifically, a value calculated by the method described in Examples described later. Is. Here, the transmittance of the first base material is determined by the properties of the members constituting the first base material, the surface state thereof, the complexity of the network structure, the fiber diameter, and the fibers when the first base material is a non-woven fabric. It can be adjusted to a desired range by appropriately adjusting the fused state, basis weight, thickness, etc. between them. For example, if an air-through non-woven fabric is used as the first base material as described later, the transmittance can be adjusted by changing the heat treatment conditions, fiber diameter and density of the air-through non-woven fabric.
　一実施形態において、第１の基材は、吸水層側の面が起毛されている。 In one embodiment, the surface of the first base material on the water absorption layer side is brushed.
　「基材を構成する材料」
　第１の基材を構成する材料としては、例えば、紙（衛生用紙、例えばティッシュペーパー、トイレットペーパーおよびタオル用紙）、ネット、不織布、織布、フィルム等が挙げられる。中でも、透水性の観点から、少なくとも第１の基材は、好ましくは不織布が使用される。 "Materials that make up the base material"
Examples of the material constituting the first base material include paper (sanitary paper, for example, tissue paper, toilet paper and towel paper), net, non-woven fabric, woven cloth, film and the like. Above all, from the viewpoint of water permeability, a non-woven fabric is preferably used as at least the first base material.
　使用される不織布としては特に限定されないが、液体浸透性、柔軟性および吸水性シートとした際の強度の観点から、ポリエチレン（ＰＥ）、ポリプロピレン（ＰＰ）等のポリオレフィン繊維、ポリエチレンテレフタレート（ＰＥＴ）、ポリトリメチレンテレフタレート（ＰＴＴ）、ポリエチレンナフタレート（ＰＥＮ）等のポリエステル繊維、ナイロン等のポリアミド繊維、レーヨン繊維、その他の合成繊維からなる不織布や、綿、絹、麻、パルプ（セルロース）繊維等が混合されて製造された不織布等が挙げられる。 The non-woven fabric used is not particularly limited, but from the viewpoint of liquid permeability, flexibility and strength when made into a water-absorbent sheet, polyolefin fibers such as polyethylene (PE) and polypropylene (PP), polyethylene terephthalate (PET), and the like. Non-woven fabrics made of polyester fibers such as polytrimethylene terephthalate (PTT) and polyethylene naphthalate (PEN), polyamide fibers such as nylon, rayon fibers, and other synthetic fibers, cotton, silk, linen, pulp (cellulose) fibers, etc. Examples thereof include non-woven fabrics produced by mixing.
　第１の基材として用いられうる不織布の材質としては、レーヨン繊維、ポリオレフィン繊維、ポリエステル繊維、パルプ繊維およびこれらが混合された繊維などが好ましく、ポリオレフィン繊維であることがより好ましい。これらの繊維は親水化処理が施されていてもよい。 As the material of the non-woven fabric that can be used as the first base material, rayon fiber, polyolefin fiber, polyester fiber, pulp fiber and a fiber in which these are mixed are preferable, and polyolefin fiber is more preferable. These fibers may be hydrophilized.
　また、第１の基材として用いられうる不織布は、特に限定されるものではなく、エアスルー法；エアレイド法；スパンボンド法；スパンレース法など、いずれの方法により得られたものであってもよいが、エアスルー法またはエアレイド法で得られたものであることが好ましく、エアスルー法で得られたもの（エアスルー不織布）であることが好ましい。 The non-woven fabric that can be used as the first base material is not particularly limited, and may be obtained by any method such as an air-through method; an air-laid method; a spunbond method; a spunlace method. Is preferably obtained by the air-through method or the air-laid method, and is preferably obtained by the air-through method (air-through non-woven fabric).
　なお、エアスルー法は、ＰＥ／ＰＰやＰＥ／ＰＥＴなどの熱融着可能な複合繊維に熱風を吹きつけて、熱融着を行うとともに、繊維の間に含まれる空気の量を増やし、嵩を高くし、密度を低くする加工のことをいう。また、エアレイド法は、空気の流れに乗せて均一分散させ、金網上に吸い取らせて不織布を作る方法であり、パルプ繊維の分散に空気を利用しているため、嵩を高くし、密度を低くすることができる。第１の基材がエアスルー不織布であることにより、吸収される液が第１の基材の吸液面に接した後、速やかに第１の基材の中へ導入されやすい。すなわち、第１の基材をエアスルー不織布にすることにより、吸水力が低く、通液力の高い第１の基材とすることができ、吸水性シートにおける逆戻り量を有意に低減することができる。 In the air-through method, hot air is blown onto heat-bondable composite fibers such as PE / PP and PE / PET to perform heat-sealing, and the amount of air contained between the fibers is increased to increase the bulk. It refers to processing that increases the density and reduces the density. In addition, the air-laid method is a method in which air is placed on an air flow to uniformly disperse it and then absorbed onto a wire mesh to form a non-woven fabric. Since air is used to disperse pulp fibers, the volume is increased and the density is reduced. can do. Since the first base material is an air-through non-woven fabric, the absorbed liquid is likely to be quickly introduced into the first base material after coming into contact with the liquid absorbing surface of the first base material. That is, by using the air-through non-woven fabric as the first base material, it is possible to use the first base material having low water absorption and high liquid permeability, and the amount of reversion in the water absorption sheet can be significantly reduced. ..
　［２－２．第２の基材］
　第２の基材が、透水性シートであり、かつ、吸液される側の反対側に位置することで、本発明の効果である吸水性シートの性能（逆戻り量、面方向の漏れなど）を充分に発揮することができる。透水性シートにおける透水性は、透水係数（ＪＩＳ　Ａ１２１８：２００９）が１×１０－５ｃｍ／ｓｅｃ以上であることが好ましい。該透水係数は、より好ましくは１×１０－４ｃｍ／ｓｅｃ以上、さらにより好ましくは１×１０－３ｃｍ／ｓｅｃ以上、特に好ましくは１×１０－２ｃｍ／ｓｅｃ以上、最も好ましくは１×１０－１ｃｍ／ｓｅｃ以上である。 [2-2. Second base material]
Since the second base material is a water-permeable sheet and is located on the opposite side to the side where the liquid is absorbed, the performance of the water-absorbent sheet (return amount, leakage in the plane direction, etc.), which is the effect of the present invention, is achieved. Can be fully demonstrated. The water permeability of the water-permeable sheet preferably has a water permeability coefficient (JIS A1218: 2009) of 1 × 10-5 cm / sec or more. The hydraulic conductivity is more preferably 1 × 10 -4 cm / sec or more, even more preferably 1 × 10 -3 cm / sec or more, particularly preferably 1 × 10 −2 cm / sec or more, and most preferably 1 × It is 10 -1 cm / sec or more.
　また、第２の基材の厚みは、例えば４０％ＲＨ～５０％ＲＨにおいて、好ましくは０．０５ｍｍ以上、より好ましくは０．０８ｍｍ以上、さらにより好ましくは０．１ｍｍ以上、特に好ましくは０．２ｍｍ以上、最も好ましくは０．３ｍｍ以上である。第２の基材の厚みは、例えば４０％ＲＨ～５０％ＲＨにおいて、好ましくは０．９ｍｍ以下、より好ましくは０．８ｍｍ以下、さらにより好ましくは０．７ｍｍ以下、特に好ましくは０．６ｍｍ以下、最も好ましくは０．５ｍｍ以下である。 The thickness of the second substrate is, for example, 40% RH to 50% RH, preferably 0.05 mm or more, more preferably 0.08 mm or more, still more preferably 0.1 mm or more, and particularly preferably 0. It is 2 mm or more, most preferably 0.3 mm or more. The thickness of the second substrate is, for example, 40% RH to 50% RH, preferably 0.9 mm or less, more preferably 0.8 mm or less, still more preferably 0.7 mm or less, and particularly preferably 0.6 mm or less. Most preferably, it is 0.5 mm or less.
　ここで、本発明の一実施形態によれば、第１の基材の厚みは０．７ｍｍ以上５ｍｍ以下であり、かつ第２の基材の厚みは０．０５ｍｍ以上０．９ｍｍ以下である。第１の基材と第２の基材との厚みを上記範囲に調整することによって、本発明の所期の効果を効率的に奏することができる。また、本発明の一形態によれば、好ましくは第１の基材の厚みは１．０ｍｍ以上４ｍｍ以下であり、かつ第２の基材の厚みは０．０８ｍｍ以上０．８ｍｍ以下であり、より好ましくは第１の基材の厚みは１．２ｍｍ以上３ｍｍ以下であり、かつ第２の基材の厚みは０．１ｍｍ以上０．７ｍｍ以下であり、さらにより好ましくは第１の基材の厚みは１．３ｍｍ以上２．５ｍｍ以下であり、かつ第２の基材の厚みは０．２ｍｍ以上０．６ｍｍ以下であり、特に好ましくは第１の基材の厚みは１．４ｍｍ以上２ｍｍ以下であり、かつ第２の基材の厚みは０．３ｍｍ以上０．５ｍｍ以下である。 Here, according to one embodiment of the present invention, the thickness of the first base material is 0.7 mm or more and 5 mm or less, and the thickness of the second base material is 0.05 mm or more and 0.9 mm or less. By adjusting the thickness of the first base material and the second base material within the above range, the desired effect of the present invention can be efficiently achieved. Further, according to one embodiment of the present invention, the thickness of the first base material is preferably 1.0 mm or more and 4 mm or less, and the thickness of the second base material is 0.08 mm or more and 0.8 mm or less. More preferably, the thickness of the first base material is 1.2 mm or more and 3 mm or less, and the thickness of the second base material is 0.1 mm or more and 0.7 mm or less, and even more preferably the thickness of the first base material. The thickness is 1.3 mm or more and 2.5 mm or less, and the thickness of the second base material is 0.2 mm or more and 0.6 mm or less, and particularly preferably the thickness of the first base material is 1.4 mm or more and 2 mm or less. And the thickness of the second base material is 0.3 mm or more and 0.5 mm or less.
　本発明において、第２の基材の嵩密度は、１ｇ／ｃｍ３以下であるのが好ましく、０．５ｇ／ｃｍ３以下であるのがより好ましく、０．３ｇ／ｃｍ３以下であるのがさらに好ましい。第２の基材の嵩密度は、好ましくは０．０５ｇ／ｃｍ３以上であり、より好ましくは０．０７ｇ／ｃｍ３以上であり、さらに好ましくは０．０８ｇ／ｃｍ３以上である。第２の基材の嵩密度がかような範囲であることにより、第２の基材へ導入された液を保持しやすく、逆戻りが低減できる。 In the present invention, the bulk density of the second substrate is preferably at 1 g / cm 3 or less, more preferably at 0.5 g / cm 3 or less, that is 0.3 g / cm 3 or less More preferred. The bulk density of the second substrate is preferably 0.05 g / cm 3 or more, more preferably 0.07 g / cm 3 or more, further preferably 0.08 g / cm 3 or more. When the bulk density of the second base material is within such a range, the liquid introduced into the second base material can be easily retained, and reversion can be reduced.
　本発明において、第２の基材は、目付量が５～１００ｇ／ｍ２であるのが好ましく、１０～７０ｇ／ｍ２であるのがより好ましく、１５～６５ｇ／ｍ２であるのがさらに好ましくい。 In the present invention, the second base material preferably has a basis weight of 5 to 100 g / m 2 , more preferably 10 to 70 g / m 2 , and further preferably 15 to 65 g / m 2. Preferred.
　第２の基材の厚み、嵩密度、目付量は、第２の基材を構成する材料、第２の基材の製法などによって制御することができ、これらのバランスで第２の基材の厚みや嵩密度が定まる。 The thickness, bulk density, and basis weight of the second base material can be controlled by the material constituting the second base material, the manufacturing method of the second base material, and the like. The thickness and bulk density are determined.
　なお、第１の基材、第２の基材およびラッピングシート（例えば、不織布）の空隙率は、以下の式で測定できる。基材（または、ラッピングシート）に用いられる目付量Ａ（ｇ／ｍ２）、基材（または、ラッピングシート）の厚みＢ（ｍｍ）、基材（または、ラッピングシート）に用いられる素材（例えば、ポレオレフィン）の密度Ｃ（ｇ／ｃｍ３）
　基材（または、シート）の空隙率（％）＝１００－｛（Ａ／１００００）／（Ｂ／１０）｝／Ｃ＊１００ The porosity of the first base material, the second base material and the wrapping sheet (for example, non-woven fabric) can be measured by the following formula. The basis weight A (g / m 2 ) used for the base material (or wrapping sheet), the thickness B (mm) of the base material (or wrapping sheet), and the material (for example, the wrapping sheet) used for the base material (or wrapping sheet). , Poleolefin) density C (g / cm 3 )
Porosity (%) of the base material (or sheet) = 100-{(A / 10000) / (B / 10)} / C * 100
　第２の基材は、液拡散面積が１０００ｍｍ２以上であるのが好ましく、３０００ｍｍ２以上であるのがより好ましく、６０００ｍｍ２以上であるのがさらに好ましく、特に７０００ｍｍ２以上であることが好ましい。また、第２の基材の液拡散面積の上限は特にないが、例えば１０，０００ｍｍ２以下であるのが好ましい。第２の基材の液拡散面積が上記範囲である場合、吸収された液が第２の基材に達した場合に、第２の基材においてその液を面方向に十分に拡散できる。これにより、吸水層を通過した液が多量に第２の基材に導入されても、第２の基材は局所でなく面方向に広がりながら液を吸収することになる。よって、第２の基材において十分に液を吸収および保持することができ、吸水性シートにおける逆戻り量を有意に低減することができ、かつ面方向の漏れを有意に低減することができる。 The second substrate is preferably a liquid distribution area is 1000 mm 2 or more, more preferably 3000 mm 2 or more, more preferably at 6000 mm 2 or more, and particularly preferably 7000 mm 2 or more. The upper limit of the liquid diffusion area of the second base material is not particularly limited, but is preferably 10,000 mm 2 or less, for example. When the liquid diffusion area of the second base material is within the above range, when the absorbed liquid reaches the second base material, the liquid can be sufficiently diffused in the plane direction on the second base material. As a result, even if a large amount of the liquid that has passed through the water absorption layer is introduced into the second base material, the second base material absorbs the liquid while spreading in the plane direction instead of locally. Therefore, the liquid can be sufficiently absorbed and retained in the second base material, the amount of reversion in the water-absorbent sheet can be significantly reduced, and the leakage in the plane direction can be significantly reduced.
　ここで、液拡散面積は、液が基材（例えば、不織布）に接触する際、および／または、液が基材中を、基材の面方向に対して垂直な方向で通過する際に拡散する面方向における面積を意味し、後述の実施例に記載の方法で算出される値である。基材の液拡散面積が大きいほど、その基材が面方向への液の拡散性が高いことを示す。 Here, the liquid diffusion area diffuses when the liquid comes into contact with a base material (for example, a non-woven fabric) and / or when the liquid passes through the base material in a direction perpendicular to the surface direction of the base material. It means the area in the plane direction, and is a value calculated by the method described in Examples described later. The larger the liquid diffusion area of the base material, the higher the liquid diffusibility of the base material in the plane direction.
　「基材を構成する材料」
　第２の基材を構成する材料は、好ましくは不織布が使用される。不織布の材質としては、第１の基材と同様のものが適用でき、例えば、レーヨン繊維、ポリオレフィン繊維、ポリエステル繊維、パルプ繊維およびこれらが混合された繊維などが好ましく、ポリオレフィン繊維であることがより好ましい。 "Materials that make up the base material"
As the material constituting the second base material, a non-woven fabric is preferably used. As the material of the non-woven fabric, the same material as that of the first base material can be applied, and for example, rayon fiber, polyolefin fiber, polyester fiber, pulp fiber and fiber in which these are mixed are preferable, and the non-woven fabric is more preferable. preferable.
　また、第２の基材として用いられうる不織布は、特に限定されるものではなく、エアスルー法；エアレイド法；スパンボンド法；スパンレース法など、いずれの方法により得られたものであってもよいが、エアレイド法で得られたもの（エアレイド不織布）またはスパンレース法で得られたもの（スパンレース不織布）であることが好ましい。なお、スパンレース法は、繊維を高圧水流により攻絡させる方法で、接着剤を使用しない方法である。第２の基材がエアレイド不織布やスパンレース不織布であることにより、吸水性シートにおける逆戻り量を有意に低減することができ、かつ面方向の漏れを有意に低減することができる。 The non-woven fabric that can be used as the second base material is not particularly limited, and may be obtained by any method such as an air-through method; an air-laid method; a spunbond method; a spunlace method. However, it is preferable that the material is obtained by the air-laid method (air-laid non-woven fabric) or the spun-lace method (spun-laced non-woven fabric). The spunlace method is a method in which fibers are entangled with a high-pressure water stream and does not use an adhesive. When the second base material is an air-laid non-woven fabric or a spunlace non-woven fabric, the amount of reversion in the water-absorbent sheet can be significantly reduced, and leakage in the plane direction can be significantly reduced.
　［２－３．吸水層］
　本発明の一実施形態に係る吸水性シートにおける吸水層は、粒子状吸水剤を有する。本発明の一実施形態に係る吸水性シートにおいては、吸水層の中に不織布等の他の基材が存在しないことが好ましい。 [2-3. Water absorption layer]
The water-absorbing layer in the water-absorbing sheet according to the embodiment of the present invention has a particulate water-absorbing agent. In the water-absorbent sheet according to the embodiment of the present invention, it is preferable that no other base material such as a non-woven fabric is present in the water-absorbent layer.
　（粒子状吸水剤）
　吸水層は、粒子状吸水剤を含む。なお、別途記載のない限り、吸水剤が複数種類の粒子状吸水剤の混合物である場合は、以下の記載は、当該混合物の物性に関する説明である。すなわち、粒子状吸水剤の物性は、吸水層に含まれるすべての粒子状吸水剤を混合した場合の物性である。また、粒子状吸水剤の物性は、吸水性シートから、綿状パルプなどが混じらないように粒子状吸水剤のみを取り出して物性を測定してもよい。 (Particular water absorbent)
The water absorption layer contains a particulate water absorption agent. Unless otherwise specified, when the water absorbing agent is a mixture of a plurality of types of particulate water absorbing agents, the following description is a description of the physical properties of the mixture. That is, the physical characteristics of the particulate water-absorbing agent are the physical characteristics when all the particulate water-absorbing agents contained in the water-absorbing layer are mixed. Further, the physical characteristics of the particulate water-absorbing agent may be measured by taking out only the particulate water-absorbing agent from the water-absorbent sheet so that cotton-like pulp or the like is not mixed.
　「表面張力」
　表面張力とは、固体や液体の表面積を増加させるのに必要な仕事（自由エネルギー）を単位面積当たりで表したものである。本願でいう表面張力は、粒子状吸水剤を０．９０質量％塩化ナトリウム水溶液中に分散させた際の、水溶液の表面張力をいう。なお、吸水剤の表面張力は、以下の手順により測定する。即ち、十分に洗浄された１００ｍｌのビーカーに２０℃に調整された生理食塩水５０ｍｌを入れ、まず、生理食塩水の表面張力を、表面張力計（ＫＲＵＳＳ社製のＫ１１自動表面張力計）を用いて測定する。次に、２０℃に調整した表面張力測定後の生理食塩水を含んだビーカーに、十分に洗浄された２５ｍｍ長のフッ素樹脂製回転子、および粒子状吸水剤０．５ｇを投入し、５００ｒｐｍの条件で４分間攪拌する。４分後、攪拌を止め、含水した粒子状吸水剤が沈降した後に、上澄み液の表面張力を再度同様の操作を行い測定する。なお、本発明では白金プレートを用いるプレート法を採用し、プレートは各測定前に十分脱イオン水にて洗浄し、かつ、ガスバーナーで加熱洗浄して使用する。 "surface tension"
Surface tension is the work (free energy) required to increase the surface area of a solid or liquid, expressed per unit area. The surface tension referred to in the present application refers to the surface tension of the aqueous solution when the particulate water absorbent is dispersed in the 0.90 mass% sodium chloride aqueous solution. The surface tension of the water absorbing agent is measured by the following procedure. That is, 50 ml of physiological saline adjusted to 20 ° C. was placed in a thoroughly washed 100 ml beaker, and the surface tension of the physiological saline was first measured using a surface tension meter (K11 automatic surface tension meter manufactured by KRUSS). To measure. Next, a fully washed 25 mm long fluororesin rotor and 0.5 g of a particulate water absorbent were placed in a beaker containing a physiological saline solution adjusted to 20 ° C. after measuring the surface tension, at 500 rpm. Stir for 4 minutes under the conditions. After 4 minutes, the stirring is stopped, and after the water-containing particulate water absorbent has settled, the surface tension of the supernatant is measured again by performing the same operation. In the present invention, a plate method using a platinum plate is adopted, and the plate is sufficiently washed with deionized water before each measurement and heated and washed with a gas burner before use.
　本発明の一実施形態に係る吸水性シートにおいて、粒子状吸水剤の表面張力が、以下順に、６０ｍＮ／ｍ以上、６５ｍＮ／ｍ以上、６６ｍＮ／ｍ以上、６７ｍＮ／ｍ以上、６９ｍＮ／ｍ以上、７０ｍＮ／ｍ以上、７１ｍＮ／ｍ以上が好ましく、最も好ましくは７２ｍＮ／ｍ以上である。粒子状吸水剤の吸水性シートへの適用では従来の紙オムツよりも表面張力の影響が表れやすく、表面張力が上記の条件を満たすことにより、吸水性シートにおける逆戻り量を低減することができ、かつ面方向の漏れを低減することができる。 In the water-absorbent sheet according to the embodiment of the present invention, the surface tension of the particulate water-absorbing agent is 60 mN / m or more, 65 mN / m or more, 66 mN / m or more, 67 mN / m or more, 69 mN / m or more, in the following order. It is preferably 70 mN / m or more, 71 mN / m or more, and most preferably 72 mN / m or more. When the particulate water absorbent is applied to a water-absorbent sheet, the effect of surface tension is more likely to appear than with conventional paper diapers, and when the surface tension satisfies the above conditions, the amount of reversion in the water-absorbent sheet can be reduced. Moreover, leakage in the surface direction can be reduced.
　本発明の一実施形態に係る吸水性シートにおいて、粒子状吸水剤の表面張力の上限には特に制限はないが、現実的には７３ｍＮ／ｍ以下である。 In the water-absorbent sheet according to the embodiment of the present invention, the upper limit of the surface tension of the particulate water-absorbent is not particularly limited, but is actually 73 mN / m or less.
　本発明の一実施形態に係る吸水性シートにおいて、粒子状吸水剤のＣＲＣ（無加圧下吸水倍率）は、以下順に、３０ｇ／ｇ以上、３２ｇ／ｇ以上、３３ｇ／ｇ以上、３４ｇ／ｇ以上が好ましく、最も好ましくは３５ｇ／ｇ以上である。粒子状吸水剤のＣＲＣが上記の条件を満たすことにより、吸水性シートにおける逆戻り量を低減することができる。なお、粒子状吸水剤のＣＲＣとは、ＥＲＴ４４１．２－０２により規定されるＣｅｎｔｒｉｆｕｇｅ　Ｒｅｔｅｎｔｉｏｎ　Ｃａｐａｃｉｔｙ（遠心分離機保持容量）の略称であり、粒子状吸水剤の無加圧下吸水倍率（「吸水倍率」と称する場合もある）を意味する。具体的には、粒子状吸水剤０．２ｇを不織布製の袋に入れた後、大過剰の０．９質量％塩化ナトリウム水溶液中に３０分間浸漬して自由膨潤させ、その後、遠心分離機（２５０Ｇ）で水切りした後の吸水倍率（単位；ｇ／ｇ）のことをいう。 In the water-absorbing sheet according to the embodiment of the present invention, the CRC (water absorption ratio under no pressure) of the particulate water-absorbing agent is 30 g / g or more, 32 g / g or more, 33 g / g or more, 34 g / g or more in the following order. Is preferable, and most preferably 35 g / g or more. When the CRC of the particulate water absorbing agent satisfies the above conditions, the amount of reversion in the water absorbing sheet can be reduced. The CRC of the particulate water absorbing agent is an abbreviation for Centrifuge Retention Capacity (centrifuge holding capacity) defined by ERT441.2-02, and the water absorption ratio of the particulate water absorbing agent under no pressure (“water absorption ratio””. It may also be called). Specifically, 0.2 g of the particulate water absorbent is placed in a non-woven fabric bag, and then immersed in a large excess of 0.9 mass% sodium chloride aqueous solution for 30 minutes for free swelling, and then a centrifuge (centrifuge). It refers to the water absorption ratio (unit: g / g) after draining with 250G).
　本発明の一実施形態に係る吸水性シートにおいて、粒子状吸水剤のＡＡＰ（加圧下吸水倍率）は、吸水性シートの性能向上（戻り量が少なくなる）の観点から、以下順に、好ましくは２５ｇ／ｇ以上、さらに好ましくは２８ｇ／ｇ以上、特に好ましくは３０ｇ／ｇ以上、最も好ましくは３３ｇ／ｇ以上である。なお、粒子状吸水剤のＡＡＰとは、ＥＲＴ４４２．２－０２により規定されるＡｂｓｏｒｐｔｉｏｎ　Ａｇａｉｎｓｔ　Ｐｒｅｓｓｕｒｅの略称であり、粒子状吸水剤の加圧下吸水倍率を意味する。具体的には、粒子状吸水剤０．９ｇを大過剰の０．９質量％塩化ナトリウム水溶液に対して、１時間、２．０６ｋＰａ（２１ｇ／ｃｍ２、０．３ｐｓｉ）荷重下で膨潤させた後の吸水倍率（単位；ｇ／ｇ）のことをいう。また、ＥＲＴ４４２．２－０２には、Ａｂｓｏｒｐｔｉｏｎ　Ｕｎｄｅｒ　Ｐｒｅｓｓｕｒｅ（ＡＵＰ）と表記されているが、実質的に同一内容である。 In the water-absorbing sheet according to the embodiment of the present invention, the AAP (water absorption ratio under pressure) of the particulate water-absorbing agent is preferably 25 g in the following order from the viewpoint of improving the performance of the water-absorbing sheet (reducing the amount of return). / G or more, more preferably 28 g / g or more, particularly preferably 30 g / g or more, and most preferably 33 g / g or more. The AAP of the particulate water-absorbing agent is an abbreviation for Absorption Against Pressure defined by ERT442.2.20, and means the water absorption ratio under pressure of the particulate water-absorbing agent. Specifically, 0.9 g of the particulate water absorbent was swollen with a large excess of 0.9 mass% sodium chloride aqueous solution for 1 hour under a load of 2.06 kPa (21 g / cm 2 , 0.3 psi). It refers to the subsequent water absorption ratio (unit: g / g). Further, in ERT442.2-02, although it is described as Absorption Under Pressure (AUP), it has substantially the same contents.
　本発明の一実施形態に係る吸水性シートにおいて、粒子状吸水剤のＤＲＣ５ｍｉｎ（浸漬保持容量５分値）は、吸水性シートの性能向上（特定戻り量が少なくなる）の観点から、以下順に、好ましくは２５～５０ｇ／ｇ、さらに好ましくは３０～４５ｇ／ｇ、特に好ましくは３０～４０ｇ／ｇである。なお、粒子状吸水剤のＤＲＣ５ｍｉｎとは、５分間での無加圧下での吸水倍率を意味し、ＤＲＣ５ｍｉｎの値が大きいほど吸収速度が速いことを示している。なお、吸水剤のＤＲＣ５ｍｉｎについての詳細な説明は、米国特許出願公開第２０１９／０１１１４１１号明細書の段落「０１５１」～「０１５２」、段落「０３２８」及び段落「０４８４」～段落「０４８７」（図１を含む）の記載が参照により本明細書に援用される。 In the water-absorbent sheet according to the embodiment of the present invention, the DRC 5 min (immersion holding capacity 5 minutes value) of the particulate water-absorbing agent is in the following order from the viewpoint of improving the performance of the water-absorbent sheet (reducing the specific return amount). It is preferably 25 to 50 g / g, more preferably 30 to 45 g / g, and particularly preferably 30 to 40 g / g. The DRC5min of the particulate water-absorbing agent means the water absorption ratio under no pressurization for 5 minutes, and the larger the value of DRC5min, the faster the absorption rate. For a detailed description of the water absorbing agent DRC5min, see paragraphs "0151" to "0152", paragraphs "0328" and paragraphs "0484" to "0487" of US Patent Application Publication No. 2019/0111411 (Fig.). 1) is incorporated herein by reference.
　本発明の一実施形態に係る吸水性シートにおいて、粒子状吸水剤のＧＰＲは、後述する加圧特定戻り量評価における吸水時間の短縮、すなわち吸水速度の向上効果に優れるため、好ましくは２０ｇ／ｍｉｎ以上、より好ましくは５０ｇ／ｍｉｎ以上、さらに好ましくは７０以上、さらにより好ましくは１００ｇ／ｍｉｎ以上、特に好ましくは１５０／ｍｉｎ以上である。すなわち、粒子状吸水剤のＧＰＲが２０ｇ／ｍｉｎ以上であると、加圧特定戻り量評価において吸水時間が短縮でき、よって吸水速度が向上する。これにより、使用者の不快感を減少させることができる。かような効果は、第１の基材の吸水層側の面が起毛されていることにより効果的に発現される。粒子状吸水剤のＧＰＲの上限は特にないが、１０００ｇ／ｍｉｎ以下が好ましい。なお、粒子状吸水剤のＧＰＲとは、Ｇｅｌ　Ｐｅｒｍｅａｔｉｏｎ　Ｒａｔｅ（ゲル透過速度）の略称であり、粒子状吸水剤を荷重下で膨潤させたときの、膨潤ゲルの粒子間を通過する液の流速（単位；ｇ／ｍｉｎ）のことをいう。なお、ＧＰＲの測定方法についての詳細な説明は、国際公開第２０１９／０７４０９４号明細書の段落「０２３７」～「０２３９」（図５を含む）の記載が参照により本明細書に援用される。 In the water-absorbing sheet according to the embodiment of the present invention, the GPR of the particulate water-absorbing agent is preferably 20 g / min because it is excellent in shortening the water absorption time in the evaluation of the specific pressure return amount described later, that is, improving the water absorption rate. The above is more preferably 50 g / min or more, still more preferably 70 or more, still more preferably 100 g / min or more, and particularly preferably 150 / min or more. That is, when the GPR of the particulate water absorbing agent is 20 g / min or more, the water absorption time can be shortened in the pressure specific return amount evaluation, and thus the water absorption rate is improved. Thereby, the discomfort of the user can be reduced. Such an effect is effectively exhibited by raising the surface of the first base material on the water absorption layer side. There is no particular upper limit on the GPR of the particulate water absorbent, but it is preferably 1000 g / min or less. The GPR of the particulate water-absorbing agent is an abbreviation for Gel Permeation Rate (gel permeation rate), and the flow velocity of the liquid passing between the particles of the swelling gel when the particulate water-absorbing agent is swollen under a load (Gel Permeation Rate). Unit: g / min). For a detailed description of the method for measuring GPR, the description in paragraphs "0237" to "0239" (including FIG. 5) of International Publication No. 2019/074094 is incorporated herein by reference.
　「粒子形状」
　本発明の一実施形態に係る吸水性シートにおいて粒子状吸水剤は、その粒子形状に制限はなく、例えば、球状の粒子状吸水剤（及びその造粒物）であってもよい。好ましい実施形態としては、粒子状吸水剤は、不定形破砕状であることが好ましい。ここで、不定形破砕状とは、形状が一定でない破砕状の粒子である。逆相懸濁重合や気相重合で得られた球状粒子に比べて不定形破砕状では基材へ固定を容易にすることができるからである。本発明の一実施形態に係る粒子状吸水剤は、好ましくは水溶液重合における粉砕物である。一方、粉砕工程を経ない場合、代表的には逆相懸濁重合や重合モノマーを噴霧し重合するような液滴重合等によって得られる球状の粒子または球状粒子の造粒物は、不定形破砕状ではない。本発明の実施形態において、粒子状吸水剤の形状が不定形破砕状であると、平均真円度の高いもの（例えば、球形のもの）と比べて吸水性シートの形状保持がなされやすい。本発明の実施形態において、粒子状吸水剤の平均真円度は、０．７０以下であることが好ましく、０．６０以下であることがより好ましく、０．５５以下であることがさらに好ましい。 "Particle shape"
In the water-absorbent sheet according to the embodiment of the present invention, the particle-like water-absorbent is not limited in its particle shape, and may be, for example, a spherical particle-like water-absorbent (and its granulated product). In a preferred embodiment, the particulate water absorbent is preferably in the form of amorphous crushed material. Here, the amorphous crushed particles are crushed particles having a non-constant shape. This is because the amorphous crushed particles can be easily fixed to the substrate as compared with the spherical particles obtained by reverse phase suspension polymerization or vapor phase polymerization. The particulate water absorbent according to one embodiment of the present invention is preferably a pulverized product in aqueous solution polymerization. On the other hand, when not undergoing the pulverization step, spherical particles or granulated products of spherical particles obtained by reverse phase suspension polymerization or droplet polymerization such as spraying and polymerizing a polymerization monomer are typically crushed into an indefinite form. Not in shape. In the embodiment of the present invention, when the shape of the particulate water absorbing agent is amorphous and crushed, the shape of the water absorbing sheet is more likely to be maintained as compared with the one having a high average roundness (for example, a spherical one). In the embodiment of the present invention, the average roundness of the particulate water absorbent is preferably 0.70 or less, more preferably 0.60 or less, and further preferably 0.55 or less.
　平均真円度の算出方法は以下のとおりである。ランダムに１００個以上の粒子状吸水剤を選択し、各粒子状吸水剤を電子顕微鏡（株式会社キーエンス社製　ＶＥ－９８００）（倍率５０倍）で撮影して粒子状吸水剤の画像を取得し、付属の画像解析ソフトを用いて粒子ごとに周囲長および面積を算出した。以下の式： The calculation method of the average roundness is as follows. 100 or more particulate water absorbents are randomly selected, and each particulate water absorbent is photographed with an electron microscope (VE-9800 manufactured by Keyence Co., Ltd.) (magnification 50 times) to obtain an image of the particulate water absorbent. , The peripheral length and area were calculated for each particle using the attached image analysis software. The following formula:
Figure JPOXMLDOC01-appb-M000001
Figure JPOXMLDOC01-appb-M000001
で各粒子の真円度を求め、得られた値の平均値を平均真円度として算出する。 The roundness of each particle is obtained with, and the average value of the obtained values is calculated as the average roundness.
　「粒子径」
　本発明の一実施形態に係る粒子状吸水剤（もしくは、粒子状の吸水性樹脂、吸水性樹脂粒子）の粒子径は、ＥＲＴ４２０．２－０２に規定される「ＰＳＤ」の測定方法に従って得られた重量平均粒子径であり、１５０～６００μｍであってよい。 "Particle size"
The particle size of the particulate water-absorbing agent (or particulate water-absorbent resin, water-absorbent resin particles) according to the embodiment of the present invention is obtained according to the measurement method of "PSD" specified in ERT420.2-02. The weight average particle size is 150 to 600 μm.
　粒子状吸水剤の製造方法は、所望の物性を有する吸水剤の製造方法であれば、特に限定されず、例えば、実施例に記載の公報等を参酌して適宜製造することができる。 The method for producing the particulate water-absorbing agent is not particularly limited as long as it is a method for producing the water-absorbing agent having desired physical properties, and for example, it can be appropriately produced in consideration of the publications described in the examples.
　〔２－４．ラッピングシート〕
　本発明の一実施形態に係る吸水性シートにおいて、少なくとも、第１の基材の表面に配置させるラッピングシートを有することが好ましい。ラッピングシートは、第１の基材の表面に配置されていればよいが、ラッピングシートが、第１の基材の側面と、吸水層の側面とを覆うように配置されるのがより好ましく、第１の基材の側面と、吸水層の側面と、第２の基材の側面とを覆い、第２の基材の吸収される液が導入される側とは反対側の面の一部または全体を覆うのがさらに好ましい。 [2-4. Wrapping sheet]
In the water-absorbent sheet according to the embodiment of the present invention, it is preferable to have at least a wrapping sheet to be arranged on the surface of the first base material. The wrapping sheet may be arranged on the surface of the first base material, but it is more preferable that the wrapping sheet is arranged so as to cover the side surface of the first base material and the side surface of the water absorption layer. A part of the side surface of the first base material, the side surface of the water absorption layer, and the side surface of the second base material, which are opposite to the side on which the liquid to be absorbed of the second base material is introduced. Or it is more preferable to cover the whole.
　本発明の好ましい実施形態としては、吸水性シートは、ラッピングシートを備え、ラッピングシートは、透水性シートであり、かつ、少なくとも、第１の基材の表面（吸液される側）に位置する。 In a preferred embodiment of the present invention, the water-absorbent sheet includes a wrapping sheet, and the wrapping sheet is a water-permeable sheet and is located at least on the surface (the side to be absorbed) of the first base material. ..
　また、ラッピングシートの厚みは、例えば４０％ＲＨ～５０％ＲＨにおいて、好ましくは０．００１ｍｍ以上、より好ましくは０．００５ｍｍ以上、さらにより好ましくは０．０１ｍｍ以上、特に好ましくは０．１ｍｍ以上、最も好ましくは０．２ｍｍ以上である。ラッピングシートの厚みは、例えば４０％ＲＨ～５０％ＲＨにおいて、好ましくは０．９ｍｍ未満、より好ましくは０．８ｍｍ以下、さらにより好ましくは０．７ｍｍ以下、特に好ましくは０．６ｍｍ以下、最も好ましくは０．５ｍｍ以下である。 The thickness of the wrapping sheet is, for example, 40% RH to 50% RH, preferably 0.001 mm or more, more preferably 0.005 mm or more, still more preferably 0.01 mm or more, and particularly preferably 0.1 mm or more. Most preferably, it is 0.2 mm or more. The thickness of the wrapping sheet is, for example, 40% RH to 50% RH, preferably less than 0.9 mm, more preferably 0.8 mm or less, still more preferably 0.7 mm or less, particularly preferably 0.6 mm or less, most preferably. Is 0.5 mm or less.
　本発明において、ラッピングシートの嵩密度は、１ｇ／ｃｍ３以下であるのが好ましく、０．５ｇ／ｃｍ３以下であるのがより好ましく、０．３ｇ／ｃｍ３以下であるのがさらに好ましい。ラッピングシートの嵩密度は、好ましくは０．１ｇ／ｃｍ３以上であり、より好ましくは０．１２ｇ／ｃｍ３以上であり、さらに好ましくは０．１３ｇ／ｃｍ３以上である。 In the present invention, the bulk density of the wrapping sheet is preferably at 1 g / cm 3 or less, more preferably at 0.5 g / cm 3 or less, even more preferably at 0.3 g / cm 3 or less. The bulk density of the wrapping sheet is preferably 0.1 g / cm 3 or more, more preferably 0.12 g / cm 3 or more, further preferably 0.13 g / cm 3 or more.
　本発明において、ラッピングシートは、目付量が５～１００ｇ／ｍ２であるのが好ましく、５～７０ｇ／ｍ２であるのがより好ましく、１０～６５ｇ／ｍ２であるのがさらに好ましい。 In the present invention, the basis weight of the wrapping sheet is preferably 5 to 100 g / m 2 , more preferably 5 to 70 g / m 2 , and even more preferably 10 to 65 g / m 2 .
　ラッピングシートの厚み、嵩密度、目付量は、ラッピングシートを構成する材料、ラッピングシートの製法などによって制御することができ、これらのバランスでラッピングシートの厚みや嵩密度が定まる。 The thickness, bulk density, and basis weight of the wrapping sheet can be controlled by the material constituting the wrapping sheet, the manufacturing method of the wrapping sheet, etc., and the thickness and bulk density of the wrapping sheet are determined by these balances.
　「ラッピングシートを構成する材料」
　ラッピングシートを構成する材料は、上述したラッピングシートを設ける目的を達成できるのであれば特に制限されないが、例えば、紙（衛生用紙、例えばティッシュペーパー、トイレットペーパーおよびタオル用紙）、ネット、不織布、織布、フィルム等が挙げられる。 "Materials that make up the wrapping sheet"
The material constituting the wrapping sheet is not particularly limited as long as the above-mentioned purpose of providing the wrapping sheet can be achieved, and for example, paper (sanitary paper such as tissue paper, toilet paper and towel paper), net, non-woven fabric, woven cloth. , Film and the like.
　使用される不織布としては特に限定されないが、液体浸透性、柔軟性および吸水性シートとした際の強度の観点から、ポリエチレン（ＰＥ）、ポリプロピレン（ＰＰ）等のポリオレフィン繊維、ポリエチレンテレフタレート（ＰＥＴ）、ポリトリメチレンテレフタレート（ＰＴＴ）、ポリエチレンナフタレート（ＰＥＮ）等のポリエステル繊維、ナイロン等のポリアミド繊維、レーヨン繊維、その他の合成繊維からなる不織布や、綿、絹、麻、パルプ（セルロース）繊維等が混合されて製造された不織布等が挙げられる。 The non-woven fabric used is not particularly limited, but from the viewpoint of liquid permeability, flexibility and strength when made into a water-absorbent sheet, polyolefin fibers such as polyethylene (PE) and polypropylene (PP), polyethylene terephthalate (PET), and the like. Non-woven fabrics made of polyester fibers such as polytrimethylene terephthalate (PTT) and polyethylene naphthalate (PEN), polyamide fibers such as nylon, rayon fibers, and other synthetic fibers, cotton, silk, linen, pulp (cellulose) fibers, etc. Examples thereof include non-woven fabrics produced by mixing.
　ラッピングシートとして用いられうる不織布の材質としては、レーヨン繊維、ポリオレフィン繊維、ポリエステル繊維、パルプ繊維およびこれらが混合された繊維などが好ましく、ポリオレフィン繊維であることがより好ましい。これらの繊維は親水化処理が施されていてもよい。 As the material of the non-woven fabric that can be used as the wrapping sheet, rayon fiber, polyolefin fiber, polyester fiber, pulp fiber and a fiber in which these are mixed are preferable, and polyolefin fiber is more preferable. These fibers may be hydrophilized.
　ラッピングシートとして用いられうる不織布は、特に限定されるものではなく、エアスルー法；エアレイド法；スパンボンド法；スパンレース法など、いずれの方法により得られたものであってもよいが、スパンボンド法で得られたもの（スパンボンド不織布）であることが好ましい。紙オムツ等の吸収性物品を履いた幼児が座っている場面のように、吸水性シートに加重がかかっている状態でも（加圧している状態でも）、吸水性シートに吸収された尿水が、シートからにじみ出ないように（いわゆる逆戻りしないように）撥水性を有するラッピングシートが好ましく、例えば、スパンボンド不織布が好ましい。なお、スパンボンド不織布の製造法は、原料樹脂を溶融・紡糸させ得られる連続した長い繊維を直接集積してフリースを形成する方法である。原料樹脂としては、ポリエチレン、ポリプロピレン、ポリ乳酸などが挙げられる。 The non-woven fabric that can be used as the wrapping sheet is not particularly limited, and may be obtained by any method such as an air-through method; an air-laid method; a spunbond method; a spunlace method, but the spunbond method. It is preferable that it is the one obtained in (Spunbonded non-woven fabric). The urine water absorbed by the water-absorbent sheet is absorbed even when the water-absorbent sheet is loaded (even when it is pressurized), such as when an infant wearing an absorbent item such as a disposable diaper is sitting. A wrapping sheet having water repellency so as not to ooze out from the sheet (so-called reversal) is preferable, and for example, a spunbonded non-woven fabric is preferable. The method for producing a spunbonded non-woven fabric is a method of directly accumulating long continuous fibers obtained by melting and spinning a raw material resin to form a fleece. Examples of the raw material resin include polyethylene, polypropylene, polylactic acid and the like.
　本発明の一形態によれば、第１の基材の製法と、第２の基材の製法と、ラッピングシートの製法とが異なる。このように吸水性シートを構成する各部材の製法を適切に変更することによって、本発明の所期の効果を効率的に奏することができる。本発明の一形態によれば、第１の基材が、エアスルー不織布であり、第２の基材が、エアレイド不織布、スパンレース不織布であり、ラッピングシートが、スパンボンド不織布であり、互いに異なる不織布である。かかる形態によって、本発明の所期の効果を効率的に奏することができる。 According to one embodiment of the present invention, the method for producing the first base material, the method for producing the second base material, and the method for producing the wrapping sheet are different. By appropriately changing the manufacturing method of each member constituting the water-absorbent sheet in this way, the desired effect of the present invention can be efficiently achieved. According to one embodiment of the present invention, the first base material is an air-through non-woven fabric, the second base material is an air-laid non-woven fabric and a spunlace non-woven fabric, and the wrapping sheet is a spunbond non-woven fabric, which are different non-woven fabrics. Is. With such a form, the desired effect of the present invention can be efficiently achieved.
　〔３．吸水性シートの製造方法〕
　本発明の一実施形態に係る吸水性シートの製造方法は、（１）第１の基材に粒子状吸水剤を散布する工程、および、（２）第２の基材に粒子状吸水剤を散布する工程、の少なくとも１つを含む。より具体的な製造方法の一例として、下記（ａ）～（ｄ）の製造方法が挙げられる。 [3. Manufacturing method of water-absorbent sheet]
The method for producing a water-absorbent sheet according to an embodiment of the present invention includes (1) a step of spraying a particulate water-absorbing agent on a first base material, and (2) a particle-like water-absorbing agent on a second base material. Includes at least one of the spraying steps. As an example of a more specific manufacturing method, the following manufacturing methods (a) to (d) can be mentioned.
　なお、第１の基材が起毛された面を有する場合、（ａ）～（ｄ）の製造方法の前に、第１の基材の片面を起毛させておけばよい。 When the first base material has a raised surface, one side of the first base material may be raised before the manufacturing methods (a) to (d).
　第１の基材の吸水側の面を起毛させる方法としては、特に制限されず、公知の方法を用いることができ、例えば、針、あざみの実（チーゼル）、ブラシ（刷毛）を用いた方法が挙げられる。工業的には、針布やあざみの実を巻いたローラーを回転させて、その上に布を走らせて生地の表面のスパン糸から繊維を引っ掻きだす方法により第１の基材を起毛させることができる。 The method of raising the surface of the first base material on the water absorption side is not particularly limited, and a known method can be used, for example, a method using a needle, a thistle fruit (teasel), or a brush (brush). Can be mentioned. Industrially, it is possible to raise the first substrate by rotating a roller wrapped with needle cloth or thistle fruit and running the cloth on it to scrape fibers from the spun yarn on the surface of the cloth. it can.
　例えば、ブラシを用いる方法としては、水平な面に不織布６０ｃｍを静置し、その巻き取り長さ方向の両端に対し、それぞれ不織布の幅より大きい１０ｋｇの錘を乗せ、不織布を固定する。不織布の巻き取り長さ方向の端から１０ｃｍの点に対し、垂直にブラシを差し込む。ブラシは長辺が不織布の幅方向になるように、そのブラシの毛先（毛の先端）が水平な面に接するまで差し込み、その後、ブラシを巻き取り長さ方向に対して、４０ｃｍ水平に移動させる。ブラシと錘とを不織布から取り外し、ブラシを移動させた面の不織布を切り取ることにより、起毛した不織布を得ることができる。 For example, as a method using a brush, a non-woven fabric of 60 cm is allowed to stand on a horizontal surface, and a weight of 10 kg, which is larger than the width of the non-woven fabric, is placed on both ends in the winding length direction to fix the non-woven fabric. Insert the brush vertically to a point 10 cm from the end in the winding length direction of the non-woven fabric. Insert the brush until the bristles (tips of the bristles) of the brush touch the horizontal surface so that the long side is in the width direction of the non-woven fabric, and then wind the brush and move it 40 cm horizontally with respect to the length direction. Let me. A brushed non-woven fabric can be obtained by removing the brush and the weight from the non-woven fabric and cutting off the non-woven fabric on the surface to which the brush is moved.
　起毛した不織布を得る場合の条件としては、例えば、下記の条件が好ましい。
・刷毛
　　商品名：２５ｍｍ×０．１ｍ　シールブラシ（ＰＢＴ／青）、メーカー：エスコ
　　毛丈：２５ｍｍ、毛の径：０．２ｍｍ
　　ブラシ長さ：１００ｍｍ、ブラシの幅：５ｍｍ、材質：ＰＢＴ
・ブラシの移動スピード：１６ｍ／ｍｉｎ＝０．２７ｍ／ｓ。 As the conditions for obtaining the brushed non-woven fabric, for example, the following conditions are preferable.
・ Brush Product name: 25mm x 0.1m Seal brush (PBT / blue), Manufacturer: Esco Hair length: 25mm, Hair diameter: 0.2mm
Brush length: 100 mm, brush width: 5 mm, material: PBT
-Brush movement speed: 16 m / min = 0.27 m / s.
　（ａ）第１の基材の上に、粒子状吸水剤を均一に散布する。第２の基材の上に、接着剤を均一に散布する。第１の基材の粒子状吸水剤が散布されている面と、第２の基材の接着剤が散布されている面とが対合するように重ねて、圧着する。圧着は、接着剤の溶融温度付近における加熱圧着が好ましい。 (A) The particulate water absorbing agent is evenly sprayed on the first base material. The adhesive is evenly sprayed onto the second substrate. The surface on which the particulate water absorbing agent of the first base material is sprayed and the surface on which the adhesive of the second base material is sprayed are overlapped and pressure-bonded so as to face each other. The crimping is preferably heat crimping in the vicinity of the melting temperature of the adhesive.
　（ｂ）第２の基材の上に、接着剤を均一に散布した後、粒子状吸水剤を均一に散布する。第１の基材を、第２の基材の粒子状吸水剤が散布されている面に重ねて、加熱圧着する。 (B) After uniformly spraying the adhesive on the second base material, the particulate water absorbent is uniformly sprayed. The first base material is superposed on the surface of the second base material on which the particulate water absorbing agent is sprayed, and heat-bonded.
　（ｃ）第２の基材の上に、粒子状吸水剤および、好ましくは接着剤を散布し、加熱炉を通過させて、粒子状吸水剤が散逸しない程度に固着させる。第１の基材を、第２の基材の粒子状吸水剤が散布されている面に重ねて、加熱圧着する。 (C) A particulate water-absorbing agent and preferably an adhesive are sprayed on the second base material, passed through a heating furnace, and fixed to such an extent that the particulate water-absorbing agent does not dissipate. The first base material is superposed on the surface of the second base material on which the particulate water absorbing agent is sprayed, and heat-bonded.
　（ｄ）第２の基材の上に、接着剤を溶融塗布した後、粒子状吸水剤を均一に散布して層を形成させる。第１の基材を、第２の基材の粒子状吸水剤が散布されている面に重ねて、ロールプレスなどを用いて圧着する。 (D) After melt-coating the adhesive on the second base material, the particulate water-absorbing agent is uniformly sprayed to form a layer. The first base material is placed on the surface of the second base material on which the particulate water absorbing agent is sprayed, and pressure-bonded using a roll press or the like.
　これらの方法のなかでは、接着剤を均一に塗布する観点から、（ｄ）の方法が好ましい。なお、（ａ）～（ｄ）の方法を併用して、吸水性シートを製造することもできる。 Among these methods, the method (d) is preferable from the viewpoint of uniformly applying the adhesive. The water-absorbent sheet can also be produced by using the methods (a) to (d) in combination.
　吸水層において、粒子状吸水剤の非存在領域を設ける場合、上記（ａ）～（ｄ）の方法において粒子状吸水剤を筋状に散布すればよい。具体的には、基材（例えば、第１の基材）上に筋状に散布した接着剤の上に粒子状吸水剤を散布して、その基材の粒子状吸水剤が散布されている面に他の基材を重ねて、加熱圧着もよいし、粒子状吸水剤が筋状に散布された基材（例えば、第１の基材）と対向する基材（例えば、第２の基材）に、接着剤を筋状に散布し、その粒子状吸水剤が散布されている面と、接着剤が散布されている面とが対合するように２つの基材を重ねて、加熱圧着してもよい。すなわち、下記（ａ’）～（ｄ’）の製造方法が挙げられる。 When the non-existent region of the particulate water absorbing agent is provided in the water absorbing layer, the particulate water absorbing agent may be sprayed in a streak pattern by the methods (a) to (d) above. Specifically, the particulate water-absorbing agent is sprayed on the adhesive sprayed in a streak pattern on the base material (for example, the first base material), and the particulate water-absorbing agent of the base material is sprayed. Another base material may be superposed on the surface and heat-bonded, or a base material (for example, a second base material) facing the base material (for example, the first base material) on which the particulate water absorbing agent is sprayed in a streak pattern may be used. The adhesive is sprayed on the material) in a streak pattern, and the two base materials are placed on top of each other so that the surface on which the particulate water absorbent is sprayed and the surface on which the adhesive is sprayed face each other and heated. It may be crimped. That is, the following manufacturing methods (a') to (d') can be mentioned.
　（ａ’）第１の基材の上に、粒子状吸水剤を筋状に散布する。第２の基材の上に、接着剤を均一に散布する。第１の基材の粒子状吸水剤が散布されている面と、第２の基材の接着剤が散布されている面とが対合するように重ねて、圧着する。圧着は、接着剤の溶融温度付近における加熱圧着が好ましい。 (A') Sprinkle the particulate water absorbent on the first base material in a streak pattern. The adhesive is evenly sprayed onto the second substrate. The surface on which the particulate water absorbing agent of the first base material is sprayed and the surface on which the adhesive of the second base material is sprayed are overlapped and pressure-bonded so as to face each other. The crimping is preferably heat crimping in the vicinity of the melting temperature of the adhesive.
　（ｂ’）第２の基材の上に、接着剤を筋状に散布した後、粒子状吸水剤を均一に散布する。第１の基材を、第２の基材の粒子状吸水剤が散布されている面に重ねて、加熱圧着する。 (B') After spraying the adhesive in a streak pattern on the second base material, the particulate water absorbent is uniformly sprayed. The first base material is superposed on the surface of the second base material on which the particulate water absorbing agent is sprayed, and heat-bonded.
　（ｃ’）第２の基材の上に、粒子状吸水剤を筋状に散布し、および、好ましくは接着剤を均一に散布し、加熱炉を通過させて、粒子状吸水剤が散逸しない程度に固着させる。第１の基材を、第２の基材の粒子状吸水剤が散布されている面に重ねて、加熱圧着する。 (C') On the second base material, the particulate water absorbent is sprayed in a streak pattern, and preferably the adhesive is evenly sprayed and passed through a heating furnace so that the particulate water absorbent does not dissipate. Stick to a degree. The first base material is superposed on the surface of the second base material on which the particulate water absorbing agent is sprayed, and heat-bonded.
　（ｄ’）第２の基材の上に、接着剤を溶融塗布した後、粒子状吸水剤を筋状に散布して層を形成させる。第１の基材を、第２の基材の粒子状吸水剤が散布されている面に重ねて、ロールプレスなどを用いて圧着する。 (D') After melt-coating the adhesive on the second base material, the particulate water-absorbing agent is sprayed in a streak pattern to form a layer. The first base material is placed on the surface of the second base material on which the particulate water absorbing agent is sprayed, and pressure-bonded using a roll press or the like.
　ここで、本発明において、粒子状吸水剤を筋状に散布する方法としては、特に制限されないが、例えば、型紙を用いることにより筋状に散布することができる。具体的には、吸水性シートと同じサイズで、一定の幅および長さで並んだ縞状のパターンで繰りぬかれたプレートを型紙として用いる。この型紙を、粒子状吸水剤を散布したい基材上に載せ、繰りぬかれた穴の部分に対して、粒子状吸水剤を散布する。粒子状吸水剤を散布後、型紙を取りはずすと、基材上には粒子状吸水剤が筋状に散布された状態となる。 Here, in the present invention, the method of spraying the particulate water absorbing agent in a streak pattern is not particularly limited, but for example, it can be sprayed in a streak pattern by using a paper pattern. Specifically, a plate having the same size as the water-absorbent sheet and hollowed out in a striped pattern arranged in a certain width and length is used as a paper pattern. This paper pattern is placed on a base material on which the particulate water absorbing agent is to be sprayed, and the particulate water absorbing agent is sprayed on the hollowed-out holes. When the paper pattern is removed after spraying the particulate water-absorbing agent, the particulate water-absorbing agent is sprayed in a streak pattern on the base material.
　また、スクリーン印刷等により接着剤を基材上に縞状に塗布し、当該基材上に粒子状吸水剤を散布した後、基材上の接着剤と接触していない粒子状吸水剤を払い落とすことにより、基材上に粒子状吸水剤を筋状に散布することもできる。 In addition, the adhesive is applied in stripes on the base material by screen printing or the like, the particulate water absorbent is sprayed on the base material, and then the particulate water absorbent that is not in contact with the adhesive on the base material is removed. By dropping it, the particulate water-absorbing agent can be sprayed on the base material in a streak pattern.
　また、図１～図４のように吸水性シートがラッピングシートを備えている形態においては、（３）第１の基材と吸水層と第２の基材とを、第１の基材上に配置させたラッピングシートにより覆う工程を含む。例えば、上記（ａ）または（ｂ）の工程を経て得られた第１の基材と吸水層と第２の基材とが圧着されたシートを、第１の基材を下にして、ラッピングシートの上に載せ、上面である第２の基材（吸水層が圧着されていない側の面）に接着剤を散布し、第１の基材からはみ出したラッピングシートの余った部分を折り曲げて、第２の基材の接着剤面とラッピングシートが接触するように包み、上下が逆になるようひっくり返した後、加圧圧着することで、ラッピングシートを備えた吸水性シートを得ることができる。 Further, in the form in which the water-absorbent sheet includes the wrapping sheet as shown in FIGS. 1 to 4, (3) the first base material, the water-absorbent layer, and the second base material are placed on the first base material. Including the step of covering with a wrapping sheet arranged in. For example, a sheet obtained by crimping the first base material, the water absorption layer, and the second base material obtained through the steps (a) or (b) above is wrapped with the first base material facing down. Place it on the sheet, spray the adhesive on the second base material (the side where the water absorption layer is not crimped), which is the upper surface, and bend the remaining part of the wrapping sheet that protrudes from the first base material. , The adhesive surface of the second base material and the wrapping sheet are wrapped so as to be in contact with each other, turned upside down, and then pressure-bonded to obtain a water-absorbent sheet having the wrapping sheet. it can.
　以上に説明した以外の工程として、吸水性シートの触感を改善し、液体吸収性能を向上させる目的で、吸水性シートにエンボス加工を施してもよい。エンボス加工は、第１の基材および第２の基材を圧着する際に同時に施してもよいし、シート製造後に施してもよい。また、ラッピングシートにエンボス加工を施してもよい。 As a process other than those described above, the water-absorbent sheet may be embossed for the purpose of improving the tactile sensation of the water-absorbent sheet and improving the liquid absorption performance. The embossing may be performed at the same time when the first base material and the second base material are crimped, or may be performed after the sheet is manufactured. Further, the wrapping sheet may be embossed.
　本発明の一実施形態に係る吸水性シートの製造方法においては、添加剤（消臭剤、繊維、抗菌剤、ゲル安定剤など）を適宜配合してもよい。添加剤の配合量は、粒子状吸水剤の質量に対して好ましくは０～５０質量％であり、より好ましくは１～１０質量％である。上記製造方法においては、予め添加剤を混合した粒子状吸水剤を用いてもよいし、製造工程の途中で添加剤を添加してもよい。 In the method for producing a water-absorbent sheet according to an embodiment of the present invention, additives (deodorant, fiber, antibacterial agent, gel stabilizer, etc.) may be appropriately added. The blending amount of the additive is preferably 0 to 50% by mass, and more preferably 1 to 10% by mass with respect to the mass of the particulate water absorbing agent. In the above-mentioned production method, a particulate water-absorbing agent mixed with an additive in advance may be used, or an additive may be added in the middle of the production process.
　製造される吸水性シートの寸法は、適宜設計されうる。通常は、横幅が３～１０ｍ、長さが数１０ｍ～数１０００ｍ（連続シートまたはロールの状態において）である。製造された吸水性シートは、目的（使用される吸収体の大きさ）に応じて裁断して用いられる。 The dimensions of the manufactured water-absorbent sheet can be designed as appropriate. Usually, the width is 3 to 10 m and the length is several tens to several thousand m (in the state of continuous sheet or roll). The manufactured water-absorbent sheet is cut and used according to the purpose (size of the absorbent body used).
　上記に例示した以外にも、吸水性シートの製造方法は、例えば以下の特許文献に開示されている：国際公開第２０１２／１７４０２６号、国際公開第２０１３／０７８１０９号、国際公開第２０１５／０４１７８４号、国際公開第２０１１／１１７１８７号、国際公開第２０１２／００１１１７号、国際公開第２０１２／０２４４４５号、国際公開第２０１０／００４８９４号、国際公開第２０１０／００４８９５号、国際公開第２０１０／０７６８５７号、国際公開第２０１０／０８２３７３号、国際公開第２０１０／１１３７５４号、国際公開第２０１０／１４３６３５号、国際公開第２０１１／０４３２５６号、国際公開第２０１１／０８６８４１号、国際公開第２０１１／０８６８４２号、国際公開第２０１１／０８６８４３号、国際公開第２０１１／０８６８４４号、国際公開第２０１１／１１７９９７号、国際公開第２０１１／１１８４０９号、国際公開第２０１１／１３６０８７号、国際公開第２０１２／０４３５４６号、国際公開第２０１３／０９９６３４号、国際公開第２０１３／０９９６３５号、特開２０１０－１１５４０６号、特開２００２－３４５８８３号、特開平６－３１５５０１号、特開平６－１９０００３号、特開平６－１９０００２号、特開平６－１９０００１号、特開平２－２５２５５８号、特開平２－２５２５６０号、特開平２－２５２５６１号。これらの文献に開示されている吸水性シートの製造方法も、適宜参照される。 In addition to those exemplified above, methods for producing water-absorbent sheets are disclosed, for example, in the following patent documents: International Publication No. 2012/174026, International Publication No. 2013/078109, International Publication No. 2015/041784. , International Publication No. 2011/117187, International Publication No. 2012/001117, International Publication No. 2012/0244445, International Publication No. 2010/004894, International Publication No. 2010/004895, International Publication No. 2010/0768557, International Publication No. 2010/0823373, International Publication No. 2010/113754, International Publication No. 2010/143635, International Publication No. 2011/043256, International Publication No. 2011/086841, International Publication No. 2011/088642, International Publication No. 2011/086843, International Publication No. 2011/086844, International Publication No. 2011/1197997, International Publication No. 2011 / 118409, International Publication No. 2011/136807, International Publication No. 2012/0435446, International Publication No. 2013/ 099634, International Publication No. 2013/099635, JP-A-2010-115406, JP-A-2002-345883, JP-A-6-315501, JP-A-6-190003, JP-A-6-190002, JP-A-6- 190001, Japanese Patent Application Laid-Open No. 2-252558, Japanese Patent Application Laid-Open No. 2-252560, Japanese Patent Application Laid-Open No. 2-252561. The methods for producing water-absorbent sheets disclosed in these documents are also referred to as appropriate.
　本発明の一実施形態に係る吸水性シートにおいて、基材同士、または基材と粒子状吸水剤とを固着させる方法としては、（ｉ）圧着によってもよく、（ｉｉ）水、水溶性高分子、溶媒に溶解または分散した各種バインダーによってもよく、（ｉｉｉ）基材自体の材質の融点で基材同士をヒートシールさせてもよく、（ｉｖ）接着剤を使用して固着させてもよい。基材同士、または基材と粒子状吸水剤は、好ましくは、（ｉｖ）接着剤を使用して固着される。 In the water-absorbent sheet according to the embodiment of the present invention, as a method of fixing the base materials to each other or between the base materials and the particulate water-absorbing agent, (i) crimping may be used, and (ii) water or a water-soluble polymer. , Various binders dissolved or dispersed in a solvent may be used, the base materials may be heat-sealed at the melting point of the material of the base material itself (iii), or the base materials may be fixed by using an adhesive (iv). The base materials, or the base material and the particulate water absorbent, are preferably fixed using an (iv) adhesive.
　使用される接着剤は溶液型でもよいが、溶媒除去の手間や残存する溶媒の問題、生産性の問題から、高い生産性と残存溶媒の問題がないホットメルト接着剤が好ましい。本発明でホットメルト接着剤は、予め基材または粒子状吸水剤の表面に含有されていてもよく、別途、ホットメルト接着剤を吸水性シートの製造工程で使用してもよい。ホットメルト接着剤の形態や融点は適宜選択でき、粒子状でもよく、繊維状でよく、ネット状でもよく、フィルム状でもよく、また、加熱によって溶融させた液状でもよい。接着剤を均一に塗布する観点から、溶融したホットメルト接着剤を散布するのが好ましい。 The adhesive used may be a solution type, but a hot melt adhesive having high productivity and no problem of residual solvent is preferable because of the trouble of removing the solvent, the problem of the residual solvent, and the problem of productivity. In the present invention, the hot melt adhesive may be contained in advance on the surface of the base material or the particulate water absorbent, or the hot melt adhesive may be separately used in the process of manufacturing the water absorbent sheet. The form and melting point of the hot melt adhesive can be appropriately selected, and may be in the form of particles, fibers, nets, films, or liquids melted by heating. From the viewpoint of uniformly applying the adhesive, it is preferable to spray the melted hot melt adhesive.
　好ましい実施形態において、第１の基材の吸水層側の面が起毛されている場合、ホットメルト接着剤は、第２の基材に散布される。粒子状吸水剤が散布された第１の基材と、ホットメルト接着剤が散布された第２の基材とが、粒子状吸水剤が散布された面と、ホットメルト接着剤が散布された面とが対合するように重ね合わせ、加圧圧着することにより吸水性シートを製造することができる。 In a preferred embodiment, when the surface of the first base material on the water absorption layer side is brushed, the hot melt adhesive is sprayed on the second base material. The first base material on which the particulate water absorbent was sprayed and the second base material on which the hot melt adhesive was sprayed were sprayed on the surface on which the particulate water absorbent was sprayed and the hot melt adhesive was sprayed. A water-absorbent sheet can be manufactured by stacking the particles so as to face each other and pressure-bonding them under pressure.
　本発明に使用するホットメルト接着剤としては、適宜選択できるが、好ましくは、エチレン－酢酸ビニル共重合体接着剤、スチレン系エラストマー接着剤、ポリオレフィン系接着剤およびポリエステル系接着剤等から選ばれる１種以上が適宜使用できる。 The hot melt adhesive used in the present invention can be appropriately selected, but is preferably selected from ethylene-vinyl acetate copolymer adhesive, styrene elastomer adhesive, polyolefin adhesive, polyester adhesive and the like1 More than seeds can be used as appropriate.
　具体的に、ポリオレフィン系接着剤として、ポリエチレン、ポリプロピレン、アタクチックポリプロピレンが挙げられ、スチレン系エラストマー接着剤としてはスチレン－イソプレンブロック共重合体（ＳＩＳ）、スチレン－ブタジエンブロック共重合体（ＳＢＳ）、スチレン－イソブチレンブロック共重合体（ＳＩＢＳ）、スチレン－エチレン－ブチレン－スチレンブロック共重合体（ＳＥＢＳ）等のスチレンブロック共重合体が挙げられ、共重合ポリオレフィン等、ポリエステル系接着剤としてポリエチレンテレフタレート（ＰＥＴ）、ポリブチレンテレフタレート（ＰＢＴ）、共重合ポリエステル等が挙げられ、エチレン－酢酸ビニル共重合体接着剤として、エチレン－酢酸ビニル共重合体（ＥＶＡ）接着剤；エチレン－アクリル酸エチル共重合体（ＥＥＡ）、エチレン－アクリル酸ブチル共重合体（ＥＢＡ）等が挙げられる。 Specific examples of the polyolefin-based adhesive include polyethylene, polypropylene, and atactic polypropylene, and examples of the styrene-based elastomer adhesive include a styrene-isoprene block copolymer (SIS) and a styrene-butadiene block copolymer (SBS). Examples thereof include styrene block copolymers such as styrene-isobutylene block copolymer (SIBS) and styrene-ethylene-butylene-styrene block copolymer (SEBS), and polyethylene terephthalate (PET) as a polyester-based adhesive such as copolymerized polyolefin. ), Polybutylene terephthalate (PBT), copolymerized polyester, etc. As the ethylene-vinyl acetate copolymer adhesive, an ethylene-vinyl acetate copolymer (EVA) adhesive; an ethylene-ethyl acrylate copolymer ( EEA), ethylene-butyl acrylate copolymer (EBA) and the like can be mentioned.
　ホットメルト接着剤の市販品としては、例えば、ＪａｏｕｒＭｅｌｔ３８８９Ｕ（ＪＡＯＵＲ　ＨＯＴ　ＭＥＬＴ　ＡＤＨＥＳＩＶＥ社製、主成分：スチレンブロック共重合体、炭化水素樹脂、白色鉱油）、モレスコメルトＴＮ－６４０Ｚ（株式会社ＭＯＲＥＳＣＯ社製）、モレスコメルトＴＮ－７８１Ｚ（株式会社ＭＯＲＥＳＣＯ社製）、モレスコメルトＴＮ－２６２Ｚ（株式会社ＭＯＲＥＳＣＯ社製）等が挙げられる。 Commercially available hot melt adhesives include, for example, Jaour Melt 3889U (JAOUR HOT MELT ADHESIVE, main component: styrene block copolymer, hydrocarbon resin, white mineral oil), Morescomelt TN-640Z (MORESCO, Inc.), Examples thereof include Morescomelt TN-781Z (manufactured by MORESCO Co., Ltd.) and Morescomelt TN-262Z (manufactured by MORESCO Co., Ltd.).
　本発明の一実施形態に係る吸水性シートおよび／またはその製造方法において、吸水性シートが、接着剤を含むことが好ましく、当該接着剤は、ホットメルト接着剤であることが好ましく、接着剤（例えばホットメルト接着剤）の使用量（含有量）は、粒子状吸水剤の質量に対して、３．０倍以下であることが好ましく、０．０１～２．５倍であることがより好ましく、０．０５～２．０倍であることがさらに好ましい。接着剤（特にホットメルトメルト接着剤）の含有量が多すぎると、コスト面や吸水性シートの質量面（紙オムツの質量増）で不利となるだけでなく、粒子状吸水剤が膨潤規制を受けて吸水性シートの吸水能を低下させる可能性もある。 In the water-absorbent sheet and / or the method for producing the same according to an embodiment of the present invention, the water-absorbent sheet preferably contains an adhesive, and the adhesive is preferably a hot-melt adhesive, and the adhesive ( For example, the amount (content) of the hot melt adhesive) is preferably 3.0 times or less, more preferably 0.01 to 2.5 times, the mass of the particulate water absorbent. , 0.05 to 2.0 times, more preferably. If the content of the adhesive (especially hot melt melt adhesive) is too high, not only is it disadvantageous in terms of cost and the mass of the water-absorbent sheet (increased mass of the paper diaper), but also the particulate water-absorbing agent regulates swelling. In response, it may reduce the water absorption capacity of the water-absorbent sheet.
　〔４．吸収性物品〕
　本発明の一実施形態に係る吸収性物品は、〔２〕で説明されている吸水性シートを、液体透過性シートおよび液体不透過性シートによって挟持した構造を有している。ここで、液体透過性シートは、第１の基材側に位置し、液体不透過性シートが、第２の基材側に位置している。すなわち、本発明の一実施形態に係る吸収性物品は、本発明の吸水性シートを液体透過性シートと、液体不透過性シートとで挟持することによりなり、液体透過性シートが、第１の基材側に位置し、液体不透過性シートが、前記第２の基材側に位置している。吸収性物品の具体例としては、紙オムツ、失禁パッド、生理用ナプキン、ペットシート、食品用ドリップシート、電力ケーブルの止水剤などが挙げられる。 [4. Absorbent article]
The absorbent article according to one embodiment of the present invention has a structure in which the water-absorbent sheet described in [2] is sandwiched between a liquid-permeable sheet and a liquid-impermeable sheet. Here, the liquid permeable sheet is located on the first base material side, and the liquid permeable sheet is located on the second base material side. That is, the absorbent article according to the embodiment of the present invention is obtained by sandwiching the water-absorbent sheet of the present invention between the liquid-permeable sheet and the liquid-impermeable sheet, and the liquid-permeable sheet is the first. The liquid impermeable sheet is located on the base material side and is located on the second base material side. Specific examples of the absorbent article include paper diapers, incontinence pads, sanitary napkins, pet sheets, food drip sheets, water blocking agents for electric power cables, and the like.
　液体透過性シートおよび液体不透過性シートとしては、吸収性物品の技術分野で公知のものを、特に制限なく用いることができる。また、吸収性物品は、公知の方法によって製造することができる。 As the liquid permeable sheet and the liquid permeable sheet, those known in the technical field of absorbent articles can be used without particular limitation. In addition, the absorbent article can be produced by a known method.
　本発明を、以下の実施例および比較例を用いてさらに詳細に説明する。ただし、本発明の技術的範囲が以下の実施例のみに制限されるわけではない。また、下記実施例において、特記しない限り、操作は室温（２５℃）／相対湿度４０～５０％ＲＨの条件下で行われた。 The present invention will be described in more detail with reference to the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Further, in the following examples, unless otherwise specified, the operation was performed under the conditions of room temperature (25 ° C.) / relative humidity of 40 to 50% RH.
　［実施例Ａ］
　＜製造例＞
　［製造例１］
　以下の特許に記載の製造例、実施例、比較例を参考に、内部架橋剤量によって、ＣＲＣを適宜調整することで、ポリアクリル酸（塩）系樹脂の粒子状吸水剤（１）～（３）を得た。得られた粒子状吸水剤の物性を表１に示した。 [Example A]
<Manufacturing example>
[Manufacturing Example 1]
By appropriately adjusting the CRC according to the amount of the internal cross-linking agent with reference to the production examples, examples, and comparative examples described in the following patents, the particulate water absorbents (1) to (1) to polyacrylic acid (salt) -based resin. 3) was obtained. The physical characteristics of the obtained particulate water absorbent are shown in Table 1.
　国際公開第２０１４／０３４８９７号
　国際公開第２０１７／１７０６０５号
　国際公開第２０１６／２０４３０２号
　国際公開第２０１４／０５４６５６号
　国際公開第２０１５／１５２２９９号
　国際公開第２０１８／０６２５３９号
　国際公開第２０１２／０４３８２１号。 International Publication No. 2014/034897 International Publication No. 2017/170605 International Publication No. 2016/204302 International Publication No. 2014/054656 International Publication No. 2015/152299 International Publication No. 2018/062539 International Publication No. 2012/043821.
　〔アクリル酸の製造例〕
　市販のアクリル酸（アクリル酸ダイマー２０００ｐｐｍ、酢酸５００ｐｐｍ、プロピオン酸５００ｐｐｍ、ｐ－メトキシフェノール２００ｐｐｍ）を、無堰多孔板５０段を有する高沸点不純物分離塔の塔底に供給して、還流比を１として蒸留し、マレイン酸やアクリル酸からなる二量体（アクリル酸ダイマー）などの除去後、さらに晶析を行なうことで、アクリル酸（アクリル酸ダイマー２０ｐｐｍ、酢酸５０ｐｐｍ、プロピオン酸５０ｐｐｍ、フルフラール１ｐｐｍ以下、プロトアネモニン１ｐｐｍ以下）を得て、さらに蒸留後にｐ－メトキシフェノールを５０ｐｐｍ添加した。 [Acrylic acid production example]
Commercially available acrylic acid (acrylic acid dimer 2000 ppm, acetic acid 500 ppm, propionic acid 500 ppm, p-methoxyphenol 200 ppm) is supplied to the bottom of a high boiling point impurity separation tower having 50 steps of a dam-free perforated plate, and the reflux ratio is set to 1. Acrylic acid (acrylic acid dimer 20 ppm, acetic acid 50 ppm, propionic acid 50 ppm, furfural 1 ppm or less) by distilling as, after removing dimer (acrylic acid dimer) composed of maleic acid and acrylic acid, and further performing crystallization. , Protoanemonin (1 ppm or less) was obtained, and 50 ppm of p-methoxyphenol was further added after distillation.
　〔アクリル酸ナトリウム水溶液の製法〕
　上記アクリル酸１３９０ｇを米国特許５２１０２９８号の実施例９に従い、４８％苛性ソーダを用いて２０～４０℃で中和して、濃度３７％で１００％中和のアクリル酸ナトリウム水溶液を得た。 [Manufacturing method of aqueous sodium acrylate solution]
According to Example 9 of US Pat. No. 5,210,298, 1390 g of the above acrylic acid was neutralized with 48% caustic soda at 20 to 40 ° C. to obtain a 100% neutralized sodium acrylic acid aqueous solution at a concentration of 37%.
　＜粒子状吸水剤（１）＞
　上記アクリル酸の製造例で得られたアクリル酸、該アクリル酸を用いて上記アクリル酸ナトリウム水溶液の製法で得られたアクリル酸ナトリウム水溶液、および脱イオン水を混合して得られた７５モル％の中和率を有するアクリル酸ナトリウムの水溶液５５００ｇ（単量体濃度３６．０質量％）に、ポリエチレングリコールジアクリレート（エチレンオキシドの平均付加モル数９）４．１１ｇを溶解し反応液とした。次いで、シグマ型羽根を２本有する内容積１０Ｌのジャケット付きステンレス製双腕型ニーダーに蓋を付けて形成した反応器に、上記反応液を供給し、反応液を３０℃に保ちながら系を窒素ガス置換し、反応液中の溶存酸素を除去した。続いて、反応液を撹拌しながら、過硫酸ナトリウムの１０質量％水溶液２８．６６ｇおよびＬ－アスコルビン酸の１質量％水溶液３５．２８ｇを添加したところ、およそ１分後に重合が開始した。重合を開始して４０分後に含水ゲル状重合体を取り出した。得られた含水ゲル状重合体は約２～４ｍｍの粒子に細分化されていた。この細分化された含水ゲル状重合体を５０メッシュ（目の大きさ３００μｍ）の金網上に広げ、１７５℃で６５分間熱風乾燥した。次いで、乾燥物をロールミルを用いて粉砕し、さらに目開き６００μｍの金網で分級、調合することにより、平均粒子径３５０μｍの不定形破砕状の吸水性樹脂（１－１）を得た。 <Particular water absorbent (1)>
75 mol% obtained by mixing the acrylic acid obtained in the above production example of acrylic acid, the aqueous sodium acrylate solution obtained by the above method for producing an aqueous sodium acrylate solution using the acrylic acid, and deionized water. 4.11 g of polyethylene glycol diacrylate (average number of moles of ethylene oxide added 9) was dissolved in 5500 g (monomer concentration 36.0% by mass) of an aqueous solution of sodium acrylate having a neutralization rate to prepare a reaction solution. Next, the above reaction solution was supplied to a reactor formed by attaching a lid to a stainless steel double-armed kneader with an internal volume of 10 L having two sigma type blades, and the system was nitrogenized while keeping the reaction solution at 30 ° C. Gas replacement was performed to remove dissolved oxygen in the reaction solution. Subsequently, 28.66 g of a 10 mass% aqueous solution of sodium persulfate and 35.28 g of a 1 mass% aqueous solution of L-ascorbic acid were added while stirring the reaction solution, and the polymerization started after about 1 minute. 40 minutes after the start of the polymerization, the hydrogel polymer was taken out. The obtained hydrogel polymer was subdivided into particles having a size of about 2 to 4 mm. The subdivided hydrogel polymer was spread on a wire mesh of 50 mesh (mesh size 300 μm) and dried with hot air at 175 ° C. for 65 minutes. Next, the dried product was pulverized using a roll mill, further classified and blended with a wire mesh having a mesh size of 600 μm to obtain an amorphous crushed water-absorbent resin (1-1) having an average particle diameter of 350 μm.
　得られた吸水性樹脂（１－１）１００質量部に、エチレングリコールジグリシジルエーテル０．０３質量部、プロピレングリコール１．０質量部、水３．０質量部からなる表面架橋剤水溶液４．０３質量部を噴霧混合した。上記の混合物を、パドル型混合加熱処理機を用いて、熱媒温度１００℃で４０分間加熱処理して表面架橋された吸水性樹脂（１－２）を得た。得られた表面架橋された吸水性樹脂（１－２）１００質量部に、水３．０質量部を噴霧混合して、密閉容器内で６０℃で１時間硬化させた後、目開き７１０μｍのふるいを通過させて吸水性樹脂（１－３）を得た。吸水性樹脂（１－３）にＡｅｒｏｓｉｌ９０Ｇ（親水性アモルファスシリカ、日本アエロジル社製）を０．３質量部添加して混合することにより得た吸水性樹脂を粒子状吸水剤（１）とした。 A surface cross-linking agent aqueous solution containing 0.03 parts by mass of ethylene glycol diglycidyl ether, 1.0 part by mass of propylene glycol, and 3.0 parts by mass of water in 100 parts by mass of the obtained water-absorbent resin (1-1) 4.03. The parts by mass were spray-mixed. The above mixture was heat-treated at a heat medium temperature of 100 ° C. for 40 minutes using a paddle-type mixing heat treatment machine to obtain a surface-crosslinked water-absorbent resin (1-2). 3.0 parts by mass of water was spray-mixed with 100 parts by mass of the obtained surface-crosslinked water-absorbent resin (1-2) and cured at 60 ° C. for 1 hour in a closed container, and then the opening was 710 μm. A water-absorbent resin (1-3) was obtained by passing through a sieve. The water-absorbent resin obtained by adding 0.3 parts by mass of Aerosil 90G (hydrophilic amorphous silica, manufactured by Nippon Aerosil Co., Ltd.) to the water-absorbent resin (1-3) and mixing them was used as a particulate water-absorbent resin (1).
　＜粒子状吸水剤（２）＞
　上記アクリル酸の製造例で得られたアクリル酸、該アクリル酸を用いて上記アクリル酸ナトリウム水溶液の製法で得られたアクリル酸ナトリウム水溶液、および脱イオン水を混合して得られた７５モル％の中和率を有するアクリル酸ナトリウムの水溶液５５００ｇ（単量体濃度３６．０質量％）に、ポリエチレングリコールジアクリレート（エチレンオキシドの平均付加モル数９）５．０１ｇを溶解し反応液とした。次いで、シグマ型羽根を２本有する内容積１０Ｌのジャケット付きステンレス製双腕型ニーダーに蓋を付けて形成した反応器に、上記反応液を供給し、反応液を３０℃に保ちながら系を窒素ガス置換し、反応液中の溶存酸素を除去した。続いて、反応液を撹拌しながら、過硫酸ナトリウムの１０質量％水溶液２９．０７ｇおよびＬ－アスコルビン酸の１質量％水溶液３５．７８ｇを添加したところ、およそ１分後に重合が開始した。重合を開始して４０分後に含水ゲル状重合体を取り出した。得られた含水ゲル状重合体は約２～４ｍｍの粒子に細分化されていた。この細分化された含水ゲル状重合体を５０メッシュ（目の大きさ３００μｍ）の金網上に広げ、１７５℃で６５分間熱風乾燥した。次いで、乾燥物をロールミルを用いて粉砕し、さらに目開き６００μｍの金網で分級、調合することにより、平均粒子径３５０μｍの不定形破砕状の吸水性樹脂（２－１）を得た。 <Particular water absorbent (2)>
75 mol% obtained by mixing the acrylic acid obtained in the above production example of acrylic acid, the aqueous sodium acrylate solution obtained by the above method for producing an aqueous sodium acrylate solution using the acrylic acid, and deionized water. 5.01 g of polyethylene glycol diacrylate (average number of moles of ethylene oxide added 9) was dissolved in 5500 g (monomer concentration 36.0% by mass) of an aqueous solution of sodium acrylate having a neutralization rate to prepare a reaction solution. Next, the above reaction solution was supplied to a reactor formed by attaching a lid to a stainless steel double-armed kneader with an internal volume of 10 L having two sigma type blades, and the system was nitrogenized while keeping the reaction solution at 30 ° C. Gas replacement was performed to remove dissolved oxygen in the reaction solution. Subsequently, 29.07 g of a 10 mass% aqueous solution of sodium persulfate and 35.78 g of a 1 mass% aqueous solution of L-ascorbic acid were added while stirring the reaction solution, and the polymerization started after about 1 minute. 40 minutes after the start of the polymerization, the hydrogel polymer was taken out. The obtained hydrogel polymer was subdivided into particles having a size of about 2 to 4 mm. The subdivided hydrogel polymer was spread on a wire mesh of 50 mesh (mesh size 300 μm) and dried with hot air at 175 ° C. for 65 minutes. Next, the dried product was pulverized using a roll mill, further classified and blended with a wire mesh having a mesh size of 600 μm to obtain an amorphous crushed water-absorbent resin (2-1) having an average particle diameter of 350 μm.
　得られた吸水性樹脂（２－１）１００質量部に、エチレングリコールジグリシジルエーテル０．０３質量部、プロピレングリコール１．０質量部、水３．０質量部からなる表面架橋剤水溶液４．０３質量部を噴霧混合した。上記の混合物を、パドル型混合加熱処理機を用いて、熱媒温度１００℃で４０分間加熱処理して表面架橋された吸水性樹脂（２－２）を得た。得られた表面架橋された吸水性樹脂（２－２）１００質量部に、水３．０質量部を噴霧混合して、密閉容器内で６０℃で１時間硬化させた後、目開き７１０μｍのふるいを通過させて吸水性樹脂（２－３）を得た。吸水性樹脂（２－３）にＡｅｒｏｓｉｌ９０Ｇ（親水性アモルファスシリカ、日本アエロジル社製）を０．３質量部添加して混合することにより得た吸水性樹脂を粒子状吸水剤（２）とした。 A surface cross-linking agent aqueous solution containing 0.03 parts by mass of ethylene glycol diglycidyl ether, 1.0 part by mass of propylene glycol, and 3.0 parts by mass of water in 100 parts by mass of the obtained water-absorbent resin (2-1) 4.03. The parts by mass were spray-mixed. The above mixture was heat-treated at a heat medium temperature of 100 ° C. for 40 minutes using a paddle-type mixing heat treatment machine to obtain a surface-crosslinked water-absorbent resin (2-2). 3.0 parts by mass of water was spray-mixed with 100 parts by mass of the obtained surface-crosslinked water-absorbent resin (2-2) and cured at 60 ° C. for 1 hour in a closed container, and then the opening was 710 μm. A water-absorbent resin (2-3) was obtained by passing through a sieve. The water-absorbent resin obtained by adding 0.3 parts by mass of Aerosil 90G (hydrophilic amorphous silica, manufactured by Nippon Aerosil Co., Ltd.) to the water-absorbent resin (2-3) and mixing them was used as a particulate water-absorbent resin (2).
　＜粒子状吸水剤（３）＞
　上記アクリル酸の製造例で得られたアクリル酸、該アクリル酸を用いて上記アクリル酸ナトリウム水溶液の製法で得られたアクリル酸ナトリウム水溶液、および脱イオン水を混合して得られた７５モル％の中和率を有するアクリル酸ナトリウムの水溶液５５００ｇ（単量体濃度３８．０質量％）に、ポリエチレングリコールジアクリレート（エチレンオキシドの平均付加モル数９）３．７７ｇを溶解し反応液とした。次いで、シグマ型羽根を２本有する内容積１０Ｌのジャケット付きステンレス製双腕型ニーダーに蓋を付けて形成した反応器に、上記反応液を供給し、反応液を３０℃に保ちながら系を窒素ガス置換し、反応液中の溶存酸素を除去した。続いて、反応液を撹拌しながら、過硫酸ナトリウムの１０質量％水溶液３０．６８ｇおよびＬ－アスコルビン酸の１質量％水溶液３７．７６ｇを添加したところ、およそ１分後に重合が開始した。重合を開始して４０分後に含水ゲル状重合体を取り出した。得られた含水ゲル状重合体は約２～４ｍｍの粒子に細分化されていた。この細分化された含水ゲル状重合体を５０メッシュ（目の大きさ３００μｍ）の金網上に広げ、１７５℃で６５分間熱風乾燥した。次いで、乾燥物をロールミルを用いて粉砕し、さらに目開き６００μｍの金網で分級、調合することにより、平均粒子径３５０μｍの不定形破砕状の吸水性樹脂（３－１）を得た。 <Particular water absorbent (3)>
75 mol% obtained by mixing the acrylic acid obtained in the above production example of acrylic acid, the aqueous sodium acrylate solution obtained by the above method for producing an aqueous sodium acrylate solution using the acrylic acid, and deionized water. 3.77 g of polyethylene glycol diacrylate (average number of moles of ethylene oxide added 9) was dissolved in 5500 g (monomer concentration 38.0% by mass) of an aqueous solution of sodium acrylate having a neutralization rate to prepare a reaction solution. Next, the above reaction solution was supplied to a reactor formed by attaching a lid to a stainless steel double-armed kneader with an internal volume of 10 L having two sigma type blades, and the system was nitrogenized while keeping the reaction solution at 30 ° C. Gas replacement was performed to remove dissolved oxygen in the reaction solution. Subsequently, 30.68 g of a 10 mass% aqueous solution of sodium persulfate and 37.76 g of a 1 mass% aqueous solution of L-ascorbic acid were added while stirring the reaction solution, and the polymerization started after about 1 minute. 40 minutes after the start of the polymerization, the hydrogel polymer was taken out. The obtained hydrogel polymer was subdivided into particles having a size of about 2 to 4 mm. The subdivided hydrogel polymer was spread on a wire mesh of 50 mesh (mesh size 300 μm) and dried with hot air at 175 ° C. for 65 minutes. Next, the dried product was pulverized using a roll mill, further classified and blended with a wire mesh having a mesh size of 600 μm to obtain an amorphous crushed water-absorbent resin (3-1) having an average particle diameter of 350 μm.
　得られた吸水性樹脂（３－１）１００質量部に、エチレングリコールジグリシジルエーテル０．０３質量部、１，４－ブタンジオール０．３質量部、プロピレングリコール０．５質量部、水３．０質量部からなる表面架橋剤水溶液３．８３質量部を噴霧混合した。上記の混合物を、パドル型混合加熱処理機を用いて、熱媒温度１９５℃で４０分間加熱処理して表面架橋された吸水性樹脂（３－２）を得た。得られた表面架橋された吸水性樹脂（３－２）１００質量部に、水１．０質量部を噴霧混合して、密閉容器内で６０℃で１時間硬化させた後、目開き７１０μｍのふるいを通過させて吸水性樹脂（３－３）を得た。吸水性樹脂（３－３）にＡｅｒｏｓｉｌ２００（親水性アモルファスシリカ、日本アエロジル社製）を０．３質量部添加して混合することにより得た吸水性樹脂を粒子状吸水剤（３）とした。 In 100 parts by mass of the obtained water-absorbent resin (3-1), 0.03 parts by mass of ethylene glycol diglycidyl ether, 0.3 parts by mass of 1,4-butanediol, 0.5 parts by mass of propylene glycol, and water 3. 3.83 parts by mass of a surface cross-linking agent aqueous solution consisting of 0 parts by mass was spray-mixed. The above mixture was heat-treated at a heat medium temperature of 195 ° C. for 40 minutes using a paddle-type mixing heat treatment machine to obtain a surface-crosslinked water-absorbent resin (3-2). 1.0 part by mass of water was spray-mixed with 100 parts by mass of the obtained surface-crosslinked water-absorbent resin (3-2) and cured at 60 ° C. for 1 hour in a closed container, and then the opening was 710 μm. A water-absorbent resin (3-3) was obtained by passing through a sieve. The water-absorbent resin obtained by adding 0.3 parts by mass of Aerosil 200 (hydrophilic amorphous silica, manufactured by Nippon Aerosil Co., Ltd.) to the water-absorbent resin (3-3) and mixing them was used as a particulate water-absorbent resin (3).
　［市販品紙オムツからの吸水性樹脂の取出し］
　＜粒子状吸水剤（４）＞
　市販の紙オムツ（ムーニーエアフィット（Ｌサイズ、Ｌｏｔ　Ｎｏ．２０１５１２１６３０７２）、ユニ・チャーム製、２０１６年５月に購入）から、吸水性樹脂を取り出した。取出しの際には、綿状パルプなどが混じらないように、吸水性樹脂のみを取り出した。取出された吸水性樹脂は、球状粒子を造粒した粒子形状であった。この吸水性樹脂を、粒子状吸水剤（４）とした。 [Removal of water-absorbent resin from commercially available paper diapers]
<Particular water absorbent (4)>
The water-absorbent resin was taken out from a commercially available disposable diaper (Moony Airfit (L size, Lot No. 201512163072), manufactured by Unicharm, purchased in May 2016). At the time of taking out, only the water-absorbent resin was taken out so as not to mix cotton-like pulp and the like. The water-absorbent resin taken out had a particle shape in which spherical particles were granulated. This water-absorbent resin was used as a particulate water-absorbent agent (4).
　〔粒子状吸水剤の物性の測定方法〕
　＜重量平均粒子径＞
　本発明の一実施形態に係る粒子状吸水剤（もしくは、粒子状の吸水性樹脂、吸水性樹脂粒子）の粒子径は、ＥＲＴ４２０．２－０２に規定される「ＰＳＤ」の測定方法に従って得られた重量平均粒子径である。各粒子状吸水剤の重量平均粒子径は表１に示す。 [Measuring method of physical properties of particulate water absorbent]
<Weight average particle size>
The particle size of the particulate water-absorbing agent (or particulate water-absorbent resin, water-absorbent resin particles) according to the embodiment of the present invention is obtained according to the measurement method of "PSD" specified in ERT420.2-02. Weight average particle size. The weight average particle size of each particulate water absorbent is shown in Table 1.
　＜ＣＲＣ（無加圧下吸水倍率）（ＥＲＴ４４１．２－０２）＞
　粒子状吸水剤０．２ｇ（吸水前重量）を不織布製の袋に入れた後、大過剰の０．９質量％塩化ナトリウム水溶液中に３０分間浸漬して自由膨潤させ、その後、遠心分離機（２５０Ｇ）で水切りした後の粒子状吸水剤の吸水後重量を測定する。吸水倍率（単位；ｇ／ｇ）は、「（粒子状吸水剤の吸水後重量－粒子状吸水剤の吸水前重量）／（粒子状吸水剤の吸水前重量）×１００」により求められる。各粒子状吸水剤のＣＲＣは表１に示す。 <CRC (Unpressurized Water Absorption Magnification) (ERT441.2-02)>
After putting 0.2 g (weight before water absorption) of the particulate water absorbent into a bag made of non-woven fabric, it is immersed in a large excess of 0.9 mass% sodium chloride aqueous solution for 30 minutes to allow free swelling, and then a centrifuge (centrifugal separator). The weight of the particulate water-absorbing agent after draining with 250G) is measured. The water absorption ratio (unit: g / g) is determined by "(weight of the particulate water absorbent after water absorption-weight of the particulate water absorbent before water absorption) / (weight of the particulate water absorbent before water absorption) x 100". The CRC of each particulate water absorbent is shown in Table 1.
　＜表面張力＞
　本発明において、表面張力は、粒子状吸水剤を０．９０質量％塩化ナトリウム水溶液中に分散させた際の、水溶液の表面張力を意味する。 <Surface tension>
In the present invention, the surface tension means the surface tension of the aqueous solution when the particulate water absorbent is dispersed in the 0.90 mass% sodium chloride aqueous solution.
　十分に洗浄された１００ｍｌのビーカーに２０℃に調整された生理食塩水５０ｍｌを入れ、まず、生理食塩水の表面張力を、表面張力計（ＫＲＵＳＳ社製のＫ１１自動表面張力計）を用いて測定する。なお、本発明では、白金プレートを用いるプレート法を採用し、プレートは各測定前に十分脱イオン水にて洗浄し、かつ、ガスバーナーで加熱洗浄して使用する。 50 ml of physiological saline adjusted to 20 ° C. is placed in a thoroughly washed 100 ml beaker, and the surface tension of the physiological saline is first measured using a surface tension meter (K11 automatic surface tension meter manufactured by KRUSS). To do. In the present invention, a plate method using a platinum plate is adopted, and the plate is sufficiently washed with deionized water before each measurement and heated and washed with a gas burner before use.
　次に、２０℃に調整した表面張力測定後の生理食塩水を含んだビーカーに、十分に洗浄された２５ｍｍ長のフッ素樹脂製回転子、および粒子状吸水剤０．５ｇを投入し、５００ｒｐｍの条件で４分間攪拌する。４分後、攪拌を止め、含水した粒子状吸水剤が沈降した後に、上澄み液の表面張力を再度同様の操作を行い測定する。ここで、粒子状吸水剤の表面張力（単位：ｍＮ／ｍ）は、生理食塩水に粒子状吸水剤を分散させた際の上澄み液の表面張力により求められる。各粒子状吸水剤の表面張力は表１に示す。 Next, a fully washed 25 mm long fluororesin rotor and 0.5 g of a particulate water absorbent were placed in a beaker containing a physiological saline solution adjusted to 20 ° C. after measuring the surface tension, at 500 rpm. Stir for 4 minutes under the conditions. After 4 minutes, the stirring is stopped, and after the water-containing particulate water absorbent has settled, the surface tension of the supernatant is measured again by performing the same operation. Here, the surface tension of the particulate water-absorbing agent (unit: mN / m) is determined by the surface tension of the supernatant liquid when the particulate water-absorbing agent is dispersed in physiological saline. The surface tension of each particulate water absorbent is shown in Table 1.
　〔実施例〕
　［実施例１］
　縦１０ｃｍ、横４０ｃｍの不織布Ｅ（パルプ繊維を主成分とする。厚み０．４ｍｍ。エアレイド法で作成されたもの。第２の基材に相当する。目付量：４７ｇ／ｍ２）に、スチレンブタジエンゴムを含む接着剤（スプレーのり７７、スリーエムジャパン株式会社製）を、０．５～０．７ｇ均一散布（散布量：１２．５～１７．５ｇ／ｍ２）した後、接着剤散布面に、粒子状吸水剤（１）を９．０ｇ（散布量：２２５ｇ／ｍ２）均一に散布した。 〔Example〕
[Example 1]
Non-woven fabric E with a length of 10 cm and a width of 40 cm (mainly composed of pulp fiber. Thickness 0.4 mm. Made by the airlaid method. Corresponds to the second base material. Grain amount: 47 g / m 2 ) and styrene. After uniformly spraying 0.5 to 0.7 g of an adhesive containing butadiene rubber (spray glue 77, manufactured by 3M Japan Ltd.) (spray amount: 12.5 to 17.5 g / m 2 ), the adhesive sprayed surface. In addition, 9.0 g (spray amount: 225 g / m 2 ) of the particulate water absorbing agent (1) was uniformly sprayed.
　次に、縦１０ｃｍ、横４０ｃｍに切断した、オレフィンを主成分とする、厚み１．４ｍｍのエアスルー不織布Ａ（第１の基材に相当する。目付量：４１ｇ／ｍ２）を、不織布Ｅの粒子状吸水剤が散布された面に載せ、加圧圧着して、中間体シートＸを得た。 Next, an air-through non-woven fabric A (corresponding to the first base material, having a basis weight: 41 g / m 2 ) having a thickness of 1.4 mm and containing olefin as a main component, which was cut into a length of 10 cm and a width of 40 cm, was applied to the non-woven fabric E. The intermediate sheet X was obtained by placing it on the surface on which the particulate water absorbing agent was sprayed and pressure-bonding it.
　次に、縦２４ｃｍ、横４０ｃｍに切断した、オレフィンを主成分とする、厚み０．１ｍｍのスパンボンド不織布（ラッピングシートに相当、目付量：１３ｇ／ｍ２、嵩密度０．１３ｇ／ｃｍ３）を敷いたところに、中間体シートＸの不織布Ａ側がスパンボンド不織布に面して接触するように載せた。 Next, a spunbonded non-woven fabric having a thickness of 0.1 mm and having an olefin as a main component, cut into a length of 24 cm and a width of 40 cm (corresponding to a wrapping sheet, a texture amount of 13 g / m 2 , a bulk density of 0.13 g / cm 3 ). The non-woven fabric A side of the intermediate sheet X was placed so as to face and contact the spunbonded non-woven fabric.
　次に、上記の中間体シートＸの不織布Ｅ側の面（上面）に、スチレンブタジエンゴムを含む接着剤（スプレーのり７７、スリーエムジャパン株式会社製）を０．１～０．２ｇ均一に散布した後、スパンボンド不織布の余った部分を折り曲げて、上記の中間体シートＸの不織布Ｅ（中間体シートＸの不織布Ｅ側の面）とスパンボンド不織布が接触するように包み、上下が逆になるようひっくり返した後、加圧圧着して、吸水性シート（１）を得た。 Next, 0.1 to 0.2 g of an adhesive containing styrene-butadiene rubber (Spray Glue 77, manufactured by 3M Japan Ltd.) was uniformly sprayed on the surface (upper surface) of the above intermediate sheet X on the non-woven fabric E side. After that, the remaining portion of the spunbonded non-woven fabric is bent and wrapped so that the non-woven fabric E of the intermediate sheet X (the surface of the intermediate sheet X on the non-woven fabric E side) and the spunbonded non-woven fabric are in contact with each other, and the top and bottom are reversed. After turning over, pressure-bonding was performed to obtain a water-absorbent sheet (1).
　［実施例２］
　縦２４ｃｍ、横４０ｃｍに切断した、オレフィンを主成分とする、厚み０．１ｍｍのスパンボンド不織布（ラッピングシートに相当）を敷いておき、その上に、縦１０ｃｍ、横４０ｃｍに切断した、オレフィンを主成分とする、厚み１．４ｍｍのエアスルー不織布Ａ（第１の基材に相当）を載せ、不織布Ａの表面に、粒子状吸水剤（１）を、９．０ｇ（散布量：２２５ｇ／ｍ２）均一に散布した。 [Example 2]
A spunbonded non-woven fabric (corresponding to a wrapping sheet) having a thickness of 0.1 mm and containing olefin as a main component, which was cut into a length of 24 cm and a width of 40 cm, was laid, and an olefin cut into a length of 10 cm and a width of 40 cm was placed on the spunbonded non-woven fabric (corresponding to a wrapping sheet). An air-through non-woven fabric A (corresponding to the first base material) having a thickness of 1.4 mm, which is the main component, is placed, and 9.0 g (spray amount: 225 g / m) of the particulate water absorbent (1) is placed on the surface of the non-woven fabric A. 2 ) It was sprayed evenly.
　次に、縦１０ｃｍ、横４０ｃｍに切断した不織布Ｅ（パルプ繊維を主成分とする。厚み０．４ｍｍ。エアレイド法で作成されたもの。第２の基材に相当する。目付量：４７ｇ／ｍ２）の表面に、スチレンブタジエンゴムを含む接着剤（スプレーのり７７、スリーエムジャパン株式会社製）を、０．５～０．７ｇ均一に散布した（散布量：１２．５～１７．５ｇ／ｍ２）。その後、不織布Ａの粒子状吸水剤を散布した面と不織布Ｅの接着剤を散布した面が対合するように（接触するように）重ね、加圧圧着した後、さらに不織布Ｅに、スチレンブタジエンゴムを含む接着剤（スプレーのり７７、スリーエムジャパン株式会社製）を０．１～０．２ｇ均一に散布して（散布量：２．５～５．０ｇ／ｍ２）、中間体シートＹを得た。 Next, the non-woven fabric E cut into a length of 10 cm and a width of 40 cm (mainly composed of pulp fiber. Thickness 0.4 mm. Made by the airlaid method. Corresponds to the second base material. Grain amount: 47 g / m An adhesive containing styrene-butadiene rubber (spray glue 77, manufactured by 3M Japan Ltd.) was uniformly sprayed on the surface of 2) in an amount of 0.5 to 0.7 g (spray amount: 12.5 to 17.5 g / m). 2 ). Then, the surface of the non-woven fabric A sprayed with the particulate water absorbent and the surface of the non-woven fabric E sprayed with the adhesive are overlapped so as to face each other (contact), pressure-bonded, and then styrene-butadiene is further applied to the non-woven fabric E. Spread 0.1 to 0.2 g of an adhesive containing rubber (spray glue 77, manufactured by 3M Japan Co., Ltd.) evenly (spray amount: 2.5 to 5.0 g / m 2 ), and apply the intermediate sheet Y. Obtained.
　次に、最下層に位置しているスパンボンド不織布の余った部分を折り曲げて、上記の中間体シートＹの不織布Ｅ（中間体シートＹの不織布Ｅ側の面）とスパンボンド不織布が接触するように包み、上下が逆になるようひっくり返した後、加圧圧着して、吸水性シート（２）を得た。 Next, the remaining portion of the spunbonded non-woven fabric located in the lowermost layer is bent so that the non-woven fabric E of the intermediate sheet Y (the surface of the intermediate sheet Y on the non-woven fabric E side) comes into contact with the spunbonded non-woven fabric. After wrapping it in a non-woven fabric and turning it upside down, pressure-bonding was performed to obtain a water-absorbent sheet (2).
　［実施例３］
　粒子状吸水剤（１）の代わりに、粒子状吸水剤（２）を用いた以外は、実施例２と同様にして、吸水性シート（３）を得た。 [Example 3]
A water-absorbing sheet (3) was obtained in the same manner as in Example 2 except that the particulate water-absorbing agent (2) was used instead of the particulate water-absorbing agent (1).
　［実施例４］
　粒子状吸水剤（１）の代わりに、粒子状吸水剤（３）を用いた以外は、実施例２と同様にして、吸水性シート（４）を得た。 [Example 4]
A water-absorbing sheet (4) was obtained in the same manner as in Example 2 except that the particulate water-absorbing agent (3) was used instead of the particulate water-absorbing agent (1).
　［実施例５］
　粒子状吸水剤（１）の代わりに、粒子状吸水剤（４）を用いた以外は、実施例２と同様にして、吸水性シート（５）を得た。 [Example 5]
A water-absorbing sheet (5) was obtained in the same manner as in Example 2 except that the particulate water-absorbing agent (4) was used instead of the particulate water-absorbing agent (1).
　［実施例６］
　エアスルー不織布Ａの代わりに、厚み２．０ｍｍのエアスルー不織布Ｂ（目付量：４３ｇ／ｍ２）を用いた以外は、実施例２と同様にして、吸水性シート（６）を得た。 [Example 6]
A water-absorbent sheet (6) was obtained in the same manner as in Example 2 except that an air-through nonwoven fabric B (with a basis weight: 43 g / m 2) having a thickness of 2.0 mm was used instead of the air-through nonwoven fabric A.
　［実施例７］
　エアスルー不織布Ａの代わりに、厚み１．５ｍｍのエアスルー不織布Ｃ（目付量：３７ｇ／ｍ２）を用いた以外は、実施例２と同様にして、吸水性シート（７）を得た。 [Example 7]
A water-absorbent sheet (7) was obtained in the same manner as in Example 2 except that an air-through nonwoven fabric C (with a basis weight: 37 g / m 2) having a thickness of 1.5 mm was used instead of the air-through nonwoven fabric A.
　［実施例８］
　エアスルー不織布Ａの代わりに、厚み１．５ｍｍのエアスルー不織布Ｄ（目付量：４５ｇ／ｍ２）を用いた以外は、実施例２と同様にして、吸水性シート（８）を得た。 [Example 8]
A water-absorbent sheet (8) was obtained in the same manner as in Example 2 except that an air-through nonwoven fabric D (weight: 45 g / m 2) having a thickness of 1.5 mm was used instead of the air-through nonwoven fabric A.
　［実施例９］
　不織布Ｅの代わりに、スパンレース不織布Ｆ（ＰＥＴ樹脂とパルプとから構成されており、厚み０．４ｍｍ、目付量４５ｇ／ｍ２）を用いた以外は、実施例２と同様にして、吸水性シート（９）を得た。 [Example 9]
Water absorption in the same manner as in Example 2 except that a spunlace non-woven fabric F (composed of PET resin and pulp, having a thickness of 0.4 mm and a grain size of 45 g / m 2) was used instead of the non-woven fabric E. Sheet (9) was obtained.
　［実施例１０］
　不織布Ａの代わりに、厚み０．７ｍｍのエアスルー不織布Ｇ（目付量：２０ｇ／ｍ２）を用いた以外は、実施例２と同様にして、吸水性シート（１０）を得た。 [Example 10]
A water-absorbent sheet (10) was obtained in the same manner as in Example 2 except that an air-through nonwoven fabric G (weight: 20 g / m 2) having a thickness of 0.7 mm was used instead of the nonwoven fabric A.
　［比較例１］
　縦１０ｃｍ、横４０ｃｍに切断した、オレフィンを主成分とする、厚み１．４ｍｍのエアスルー不織布Ａを載せ、不織布Ａの表面に、粒子状吸水剤（１）を、４．５ｇ（散布量：１１２．５ｇ／ｍ２）均一に散布した。 [Comparative Example 1]
An air-through non-woven fabric A having a thickness of 1.4 mm and containing an olefin as a main component, which was cut into a length of 10 cm and a width of 40 cm, was placed on the surface of the non-woven fabric A, and 4.5 g of the particulate water absorbent (1) was applied (spray amount: 112). .5 g / m 2 ) Sprayed evenly.
　次に、縦１０ｃｍ、横４０ｃｍに切断した不織布Ｅ（パルプ繊維を主成分とする。厚み０．４ｍｍ。エアレイド法で作成されたもの。第２の基材に相当する。目付量：４７ｇ／ｍ２）の表面に、スチレンブタジエンゴムを含む接着剤（スプレーのり７７、スリーエムジャパン株式会社製）を、０．５～０．７ｇ均一に散布した（散布量：１２．５～１７．５ｇ／ｍ２）。その後、不織布Ａの粒子状吸水剤を散布した面と不織布Ｅの接着剤を散布した面が対合するように（接触するように）重ね、加圧圧着した。 Next, the non-woven fabric E cut into a length of 10 cm and a width of 40 cm (mainly composed of pulp fiber. Thickness 0.4 mm. Made by the airlaid method. Corresponds to the second base material. Grain amount: 47 g / m An adhesive containing styrene-butadiene rubber (spray glue 77, manufactured by 3M Japan Ltd.) was uniformly sprayed on the surface of 2) in an amount of 0.5 to 0.7 g (spray amount: 12.5 to 17.5 g / m). 2 ). Then, the surface of the non-woven fabric A on which the particulate water-absorbing agent was sprayed and the surface of the non-woven fabric E on which the adhesive was sprayed were overlapped (contacted) and pressure-bonded.
　次に、粒子状吸水剤（１）と面していない側の不織布Ａの表面に、粒子状吸水剤（１）を４．５ｇ（散布量：１１２．５ｇ／ｍ２）均一に散布した。 Next, 4.5 g (spray amount: 112.5 g / m 2 ) of the particulate water absorbent (1) was uniformly sprayed on the surface of the non-woven fabric A on the side not facing the particulate water absorbent (1).
　次に、縦１０ｃｍ、横４０ｃｍに切断した不織布Ｅ（上記で用いた不織布Ｅと同様のもの（厚み０．４ｍｍ）。第１の基材に相当）の表面に、スチレンブタジエンゴムを含む接着剤（スプレーのり７７、スリーエムジャパン株式会社製）を、０．５～０．７ｇ均一に散布した（散布量：１２．５～１７．５ｇ／ｍ２）。その後、不織布Ａの粒子状吸水剤を散布した面と不織布Ｅの接着剤を散布した面が対合するように（接触するように）重ね、加圧圧着して、中間体シートＺを得た。 Next, an adhesive containing styrene-butadiene rubber on the surface of the non-woven fabric E (similar to the non-woven fabric E used above (thickness 0.4 mm), which corresponds to the first base material) cut into a length of 10 cm and a width of 40 cm. (Spray glue 77, manufactured by 3M Japan Ltd.) was uniformly sprayed in an amount of 0.5 to 0.7 g (spray amount: 12.5 to 17.5 g / m 2 ). Then, the surface of the non-woven fabric A on which the particulate water-absorbing agent was sprayed and the surface of the non-woven fabric E on which the adhesive was sprayed were overlapped (contacting each other) and pressure-bonded to obtain an intermediate sheet Z. ..
　最後に、中間体シートＺの不織布Ｅ（１回目に粒子状吸水剤を散布した不織布側）に、スチレンブタジエンゴムを含む接着剤（スプレーのり７７、スリーエムジャパン株式会社製）を０．１～０．２ｇ均一に散布（散布量：２．５～５．０ｇ／ｍ２）した後、縦２４ｃｍ、横４０ｃｍに切断した、オレフィンを主成分とする、厚み０．１ｍｍのスパンボンド不織布で包み、加圧圧着することで、吸水性シート（１１）を得た。 Finally, an adhesive containing styrene-butadiene rubber (spray glue 77, manufactured by 3M Japan Ltd.) was applied to the non-woven fabric E of the intermediate sheet Z (the non-woven fabric side on which the particulate water absorbent was sprayed for the first time) from 0.1 to 0. .2 g was uniformly sprayed (spray amount: 2.5 to 5.0 g / m 2 ), then cut into 24 cm in length and 40 cm in width, wrapped in a spunbonded non-woven fabric containing olefin as a main component and having a thickness of 0.1 mm. A water-absorbent sheet (11) was obtained by pressure-bonding.
　なお、比較例１において第１の基材に相当する不織布Ｅの粒子状吸水剤の透過率は０．３質量％であり、粒子状吸水剤の含有割合は０％であった。また、比較例１で得られた吸水性シートにおいて、「第１の基材の厚み／第２の基材の厚み」は１であった。 In Comparative Example 1, the transmittance of the particulate water-absorbing agent of the non-woven fabric E corresponding to the first base material was 0.3% by mass, and the content ratio of the particulate water-absorbing agent was 0%. Further, in the water-absorbent sheet obtained in Comparative Example 1, "thickness of the first base material / thickness of the second base material" was 1.
　［比較例２］
　縦２４ｃｍ、横４０ｃｍに切断した、オレフィンを主成分とする、厚み０．１ｍｍのスパンボンド不織布（ラッピングシートに相当）を敷いておき、その上に、縦１０ｃｍ、横４０ｃｍに切断した、オレフィンを主成分とする、厚み１．４ｍｍのエアスルー不織布Ａ（第１の基材に相当）を載せ、不織布Ａの表面に、粒子状吸水剤（１）を、９．０ｇ（散布量：２２５ｇ／ｍ２）均一に散布した。 [Comparative Example 2]
A spunbonded non-woven fabric (corresponding to a wrapping sheet) having a thickness of 0.1 mm and containing olefin as a main component, which was cut into a length of 24 cm and a width of 40 cm, was laid, and an olefin cut into a length of 10 cm and a width of 40 cm was placed on the spunbonded non-woven fabric (corresponding to a wrapping sheet). An air-through non-woven fabric A (corresponding to the first base material) having a thickness of 1.4 mm, which is the main component, is placed, and 9.0 g (spray amount: 225 g / m) of the particulate water absorbent (1) is placed on the surface of the non-woven fabric A. 2 ) It was sprayed evenly.
　次に、縦１０ｃｍ、横４０ｃｍに切断した厚み１．４ｍｍのエアスルー不織布Ａ（第２の基材に相当する。以下、この不織布Ａを便宜上、「不織布Ａ２」と称する）の表面に、スチレンブタジエンゴムを含む接着剤（スプレーのり７７、スリーエムジャパン株式会社製）を、０．５～０．７ｇ均一に散布した（散布量：１２．５～１７．５ｇ／ｍ２）。その後、この不織布Ａ２の接着剤を散布した面と、不織布Ａの粒子状吸水剤を散布した面とが対合するように（接触するように）重ね、加圧圧着した後、さらに不織布Ａ２に、スチレンブタジエンゴムを含む接着剤（スプレーのり７７、スリーエムジャパン株式会社製）を０．１～０．２ｇ均一に散布して（散布量：２．５～５．０ｇ／ｍ２）、中間体シートＺ２を得た。 Next, styrene-butadiene was placed on the surface of an air-through non-woven fabric A having a thickness of 1.4 mm (corresponding to a second base material. Hereinafter, the non-woven fabric A is referred to as "nonwoven fabric A2" for convenience) cut into a length of 10 cm and a width of 40 cm. An adhesive containing rubber (spray glue 77, manufactured by 3M Japan Ltd.) was uniformly sprayed in an amount of 0.5 to 0.7 g (spray amount: 12.5 to 17.5 g / m 2 ). Then, the surface on which the adhesive of the non-woven fabric A2 is sprayed and the surface on which the particulate water-absorbing agent of the non-woven fabric A is sprayed are overlapped so as to face each other (contact each other), pressure-bonded, and then further applied to the non-woven fabric A2. , Adhesive containing styrene-butadiene rubber (spray glue 77, manufactured by 3M Japan Ltd.) is evenly sprayed at 0.1 to 0.2 g (spray amount: 2.5 to 5.0 g / m 2 ), and the intermediate Sheet Z2 was obtained.
　次に、最下層に位置しているスパンボンド不織布の余った部分を折り曲げて、上記の中間体シートＺ２とスパンボンド不織布が接触するように包み、上下が逆になるようひっくり返した後、加圧圧着して、吸水性シート（１２）を得た。 Next, the excess portion of the spunbonded non-woven fabric located in the lowermost layer is bent, wrapped so that the above intermediate sheet Z2 and the spunbonded non-woven fabric are in contact with each other, turned upside down, and then added. Pressure crimping was performed to obtain a water-absorbent sheet (12).
　［比較例３］
　縦２４ｃｍ、横４０ｃｍに切断した、オレフィンを主成分とする、厚み０．１ｍｍのスパンボンド不織布（ラッピングシートに相当）を敷いておき、その上に、縦１０ｃｍ、横４０ｃｍに切断した、オレフィンを主成分とする、厚み１．４ｍｍのエアスルー不織布Ａ（第１の基材に相当）を載せ、不織布Ａの表面に、粒子状吸水剤（１）を、９．０ｇ（散布量：２２５ｇ／ｍ２）均一に散布した。 [Comparative Example 3]
A spunbonded non-woven fabric (corresponding to a wrapping sheet) having a thickness of 0.1 mm and containing olefin as a main component, which was cut into a length of 24 cm and a width of 40 cm, was laid, and an olefin cut into a length of 10 cm and a width of 40 cm was placed on the spunbonded non-woven fabric (corresponding to a wrapping sheet). An air-through non-woven fabric A (corresponding to the first base material) having a thickness of 1.4 mm, which is the main component, is placed, and 9.0 g (spray amount: 225 g / m) of the particulate water absorbent (1) is placed on the surface of the non-woven fabric A. 2 ) It was sprayed evenly.
　次に、最下層に位置しているスパンボンド不織布の余った部分を折り曲げて、粒子状吸水剤（１）を撒いた不織布表面とスパンボンド不織布が接触するように包み、上下が逆になるようひっくり返した後、加圧圧着して、吸水性シート（１３）を得た。なお、粒子状吸水剤（１）を撒いた不織布表面に接触するスパンボンド不織布の部分のみ、スチレンブタジエンゴムを含む接着剤（スプレーのり７７、スリーエムジャパン株式会社製）を、０．５～０．７ｇ均一に散布してから包んだ。 Next, the excess portion of the spunbonded non-woven fabric located in the bottom layer is bent and wrapped so that the surface of the non-woven fabric sprinkled with the particulate water absorbent (1) is in contact with the spunbonded non-woven fabric so that the top and bottom are turned upside down. After turning over, pressure-bonding was performed to obtain a water-absorbent sheet (13). An adhesive containing styrene-butadiene rubber (spray glue 77, manufactured by 3M Japan Ltd.) was applied only to the portion of the spunbonded non-woven fabric in contact with the surface of the non-woven fabric sprinkled with the particulate water-absorbing agent (1). 7 g was evenly sprayed and then wrapped.
　［比較例４］
　エアスルー不織布Ａの代わりに、スパンレース不織布Ｆ（ＰＥＴ樹脂とパルプから構成されており、厚み０．４ｍｍ、目付量４５ｇ／ｍ２であった）を用いた以外は、実施例２と同様にして、吸水性シート（１４）を得た。 [Comparative Example 4]
The same as in Example 2 except that the spunlace non-woven fabric F (composed of PET resin and pulp, having a thickness of 0.4 mm and a grain size of 45 g / m 2) was used instead of the air-through non-woven fabric A. , A water-absorbent sheet (14) was obtained.
　なお、比較例４において第１の基材に相当する不織布Ｆの粒子状吸水剤の透過率は１質量％であり、粒子状吸水剤の含有割合は０％であった。また、比較例４で得られた吸水性シートにおいて、「第１の基材の厚み／第２の基材の厚み」は１であった。 In Comparative Example 4, the transmittance of the particulate water-absorbing agent of the non-woven fabric F corresponding to the first base material was 1% by mass, and the content ratio of the particulate water-absorbing agent was 0%. Further, in the water-absorbent sheet obtained in Comparative Example 4, the "thickness of the first base material / the thickness of the second base material" was 1.
　なお、本実施例で使用した不織布Ａ～Ｇは、いずれも透水性シートであった。 The non-woven fabrics A to G used in this example were all water permeable sheets.
　〔不織布の物性の測定方法〕
　実施例１～１０および比較例１～４で用いた不織布Ａ～Ｆの厚み、嵩密度、液拡散面積、不織布に対する粒子状吸水剤の透過率は、以下の方法に従って測定した。 [Measuring method of physical properties of non-woven fabric]
The thickness, bulk density, liquid diffusion area, and transmittance of the particulate water absorbent to the nonwoven fabrics of the nonwoven fabrics A to F used in Examples 1 to 10 and Comparative Examples 1 to 4 were measured according to the following methods.
　＜不織布の厚み測定＞
　ダイヤルシックネスゲージ　大型タイプ（厚み測定器）（株式会社　尾崎製作所製、型番：Ｊ－Ｂ、測定子：アンビル上下φ５０ｍｍ）を用いて測定した。測定点数は、異なる箇所を５回とし、測定値は５点の平均値とした。厚み測定時は、不織布に圧力が出来るだけかからないよう、ハンドルからゆっくりと手を離し、厚みを測定した。 <Measurement of non-woven fabric thickness>
Dial thickness gauge Measured using a large type (thickness measuring instrument) (manufactured by Ozaki Seisakusho Co., Ltd., model number: JB, stylus: anvil top and bottom φ50 mm). The number of measurement points was 5 times at different points, and the measured value was an average value of 5 points. When measuring the thickness, the thickness was measured by slowly releasing the hand from the handle so that pressure was not applied to the non-woven fabric as much as possible.
　＜不織布の嵩密度の計算方法＞
　縦を１０ｃｍ以上、横を４０ｃｍ以上のサイズに切り取った不織布の重量を測定した。不織布の縦と横の長さ、および＜厚み測定＞より測り取った厚みをそれぞれ掛けて不織布の体積を計算し、不織布の重量を不織布の体積で割って嵩密度を計算した。 <Calculation method of bulk density of non-woven fabric>
The weight of the non-woven fabric cut into a size of 10 cm or more in length and 40 cm or more in width was measured. The volume of the non-woven fabric was calculated by multiplying the vertical and horizontal lengths of the non-woven fabric and the thickness measured from <thickness measurement>, respectively, and the bulk density was calculated by dividing the weight of the non-woven fabric by the volume of the non-woven fabric.
　＜不織布の液拡散面積の測定方法＞
　目開きが２ｍｍ、線形が０．９ｍｍの網を用いた直径３０ｃｍの篩を平面上に置き、１０ｃｍ四方に切り取った不織布（第２の基材）を置いた。１ｍｌのシリンジに口径０．５０ｍｍの注射針を装着して、青色１号試薬を２０ｐｐｍ含む生理食塩水１．００ｇを量りとり、篩上の不織布の中央にシリンジの生理食塩水を垂直に注入した。この時、篩の網と平面は十分に離れており、不織布と網を通過した生理食塩水は網に接しないようにした。不織布が生理食塩水を吸水して液の拡散が完了すると、生理食塩水が拡散している面積を測定した。 <Measurement method of liquid diffusion area of non-woven fabric>
A sieve having a diameter of 30 cm using a net having a mesh size of 2 mm and an alignment of 0.9 mm was placed on a flat surface, and a non-woven fabric (second base material) cut into 10 cm squares was placed. An injection needle having a diameter of 0.50 mm was attached to a 1 ml syringe, 1.00 g of physiological saline containing 20 ppm of Blue No. 1 reagent was weighed, and the physiological saline of the syringe was vertically injected into the center of the non-woven fabric on the sieve. .. At this time, the mesh of the sieve and the flat surface were sufficiently separated from each other so that the non-woven fabric and the physiological saline passing through the mesh did not come into contact with the mesh. When the non-woven fabric absorbed the physiological saline and the diffusion of the liquid was completed, the area where the physiological saline was diffused was measured.
　＜不織布に対する粒子状吸水剤の透過率＞
　目開き８５０μｍのメッシュ３２を有するＪＩＳ標準篩（Ｔｈｅ　ＩＩＤＡ　ＴＥＳＴＩＮＧ　ＳＩＥＶＥ：内径８０ｍｍ；ＪＩＳ　Ｚ８８０１－１（２０００））、またはＪＩＳ標準篩に相当する篩３１の中に、直径８０ｍｍに切断した不織布（第１の基材１１）を図５に示すように設置し、周囲をテープ３３でとめた（少なくとも直径７５ｍｍ以上は粒子が透過可能な面積を確保する）。不織布（第１の基材１１）は後述の方法により、吸水性シートから取り出したものを使用してもよい。篩３１の中の不織布（第１の基材１１）上（図５の矢印の方向）から、粒子状吸水剤１４（重量平均粒子径：３６７μｍ、粒度分布：８５０μｍ～６００μｍが６．１％　６００μｍ～５００μｍが１４．５％　５００μｍ～３００μｍが５０％　３００μｍ～１５０μｍが２７．６％　１５０μｍ～４５μｍが１．９％　４５μｍ以下０．１％）１０．０ｇを投入し、ロータップ型ふるい振盪機（株式会社飯田製作所製ＥＳ－６５型ふるい振盪機；回転数２３０ｒｐｍ、衝撃数１３０ｒｐｍ）を用いて、室温（２０～２５℃）、相対湿度５０％ＲＨの条件下で５分間振盪した。振盪後、不織布（第１の基材１１）と上記ＪＩＳ標準篩に相当する篩３１のメッシュ３２を通過した粒子状吸水剤１４（すなわち、篩３１のメッシュ３２より下部分３１ａに存在する粒子状吸水剤１４）の質量（Ｗ（ｇ））を測定し、下記式（ｉ）にしたがって、粒子状吸水剤の透過率を算出した。なお、測定は３回行い、その平均値を算出した。表１では、粒子状吸水剤の透過率（質量％）を「透過率（質量％）」と示す。 <Transmittance of particulate water absorbent to non-woven fabric>
A JIS standard sieve (The IIDA TESTING SIEVE: inner diameter 80 mm; JIS Z8801-1 (2000)) having a mesh 32 with an opening of 850 μm, or a non-woven fabric cut to a diameter of 80 mm in a sieve 31 corresponding to the JIS standard sieve (No. 1). The base material 11) of No. 1 was installed as shown in FIG. 5, and the periphery was fastened with a tape 33 (at least a diameter of 75 mm or more secures an area through which particles can permeate). As the non-woven fabric (first base material 11), one taken out from the water-absorbent sheet by the method described later may be used. From the top of the non-woven fabric (first base material 11) in the sieve 31 (in the direction of the arrow in FIG. 5), the particulate water absorbent 14 (weight average particle diameter: 367 μm, particle size distribution: 850 μm to 600 μm is 6.1% 600 μm). ~ 500 μm is 14.5% 500 μm ~ 300 μm is 50% 300 μm ~ 150 μm is 27.6% 150 μm ~ 45 μm is 1.9% 45 μm or less 0.1%) 10.0 g is added and a low tap type sieve shaker (stock) Using an ES-65 type sieve shaker manufactured by Iida Seisakusho Co., Ltd .; rotation speed 230 rpm, impact number 130 rpm), the particles were shaken for 5 minutes under the conditions of room temperature (20 to 25 ° C.) and relative humidity of 50% RH. After shaking, the particulate water absorbing agent 14 (that is, particles existing in the portion 31a below the mesh 32 of the sieve 31) has passed through the non-woven fabric (first base material 11) and the mesh 32 of the sieve 31 corresponding to the JIS standard sieve. The mass (W (g)) of the water absorbing agent 14) was measured, and the transmittance of the particulate water absorbing agent was calculated according to the following formula (i). The measurement was performed three times, and the average value was calculated. In Table 1, the transmittance (mass%) of the particulate water absorbent is shown as "transmittance (mass%)".
Figure JPOXMLDOC01-appb-M000002
Figure JPOXMLDOC01-appb-M000002
　＜吸水性シートからの粒子状吸水剤の取出し方法＞
　吸水性シートから上方不織布、および下方の不織布を剥がすことで粒子状吸水剤（中間シートを含む場合は中間シートと粒子状吸水剤と）を取り出した。上方および下方の不織布や中間シートに貼着した粒子状吸水剤も全て取り出した。上方および下方の不織布を剥がす際には、吸水性シートを冷却し、不織布や粒子状吸水剤を貼着している接着剤（ホットメルト接着剤やスプレー糊）の接着性を十分に弱めた後に剥がした。この手順を踏むことで、不織布の繊維や構造厚みを変化させることなく取り出すことができ、正確に透過率を測定することが可能になる。吸水性シートの冷却方法は－１０℃以下の恒温槽に一定時間入れる、冷却スプレーを吹きかける、液体窒素をかける等、種々手段が考えられるが、不織布の繊維や構造、厚みを変化させることなく、かつ吸水性シートに含まれる粒子状吸水剤が吸湿しない条件で行うのであれば、特に限定されない。 <Method of removing the particulate water-absorbing agent from the water-absorbing sheet>
By peeling the upper non-woven fabric and the lower non-woven fabric from the water-absorbent sheet, the particulate water-absorbing agent (in the case of containing the intermediate sheet, the intermediate sheet and the particulate water-absorbing agent) was taken out. All the particulate water absorbents attached to the upper and lower non-woven fabrics and the intermediate sheet were also taken out. When peeling off the upper and lower non-woven fabrics, cool the water-absorbent sheet to sufficiently weaken the adhesiveness of the adhesive (hot melt adhesive or spray glue) to which the non-woven fabric or particulate water-absorbing agent is attached. I peeled it off. By following this procedure, the fibers of the non-woven fabric and the structural thickness can be taken out without changing, and the transmittance can be measured accurately. Various means can be considered for cooling the water-absorbent sheet, such as putting it in a constant temperature bath at -10 ° C or lower for a certain period of time, spraying a cooling spray, or spraying liquid nitrogen, but without changing the fiber, structure, or thickness of the non-woven fabric. Moreover, it is not particularly limited as long as it is carried out under the condition that the particulate water absorbing agent contained in the water absorbing sheet does not absorb moisture.
　また、取出した粒子状吸水剤が吸湿している場合、例えば乾燥することで、含水率を１０質量％以下、好ましくは５±２質量％に調整して、上記透過率や本願で規定する諸物性を測定すればよい。含水率を調整するための乾燥条件としては、吸水性樹脂（粒子状吸水剤）の分解や変性が生じない条件ならば特に限定されないが、好ましくは減圧乾燥が良い。 When the extracted particulate water absorbing agent absorbs moisture, for example, by drying, the water content is adjusted to 10% by mass or less, preferably 5 ± 2% by mass, and the above-mentioned transmittance and various specifications specified in the present application. Physical properties may be measured. The drying conditions for adjusting the water content are not particularly limited as long as the water-absorbent resin (particulate water-absorbing agent) is not decomposed or modified, but vacuum drying is preferable.
　＜上方不織布（第１の基材に相当）中における粒子状吸水剤の含有割合の測定＞
　上方不織布を縦１０ｍｍ、横１０ｍｍの正方形に切り取ったもの（厚みはそのまま）を、株式会社島津製作所製マイクロフォーカスＸ線ＣＴシステム　ｉｎｓｐｅＸｉｏ　ＳＭＸ－１００ＣＴにより測定を行った。測定条件を以下に記す。 <Measurement of the content ratio of the particulate water absorbent in the upper non-woven fabric (corresponding to the first base material)>
A square piece of the upper non-woven fabric having a length of 10 mm and a width of 10 mm (with the same thickness) was measured by a microfocus X-ray CT system inspexio SMX-100CT manufactured by Shimadzu Corporation. The measurement conditions are described below.
　［Ｘ線ＣＴによる撮影］
　画像横サイズ（ｐｉｘｅｌ）：５１２
　画像縦サイズ（ｐｉｘｅｌ）：５１２
　Ｘ線管電圧（ｋＶ）：５０
　Ｘ線管電流（μＡ）：４０
　インチサイズ（ｉｎｃｈ）：４．０
　Ｘ線フィルタ：なし
　ＳＤＤ（Ｘ線源の焦点とＸ線検出器の距離）（ｍｍ）：７００
　ＳＲＤ（Ｘ線源の焦点と測定試料の回転中心の距離）（ｍｍ）：５５０
　走査モード　１：ＣＢＣＴ
　走査モード　２：ノーマル走査
　走査角度：フル走査
　ビュー数：２４００
　アベレージ数：５
　スムージング：ＹＺ
　スライス厚（ｍｍ）：０．１６６
　ＢＨＣデータ：なし
　精細モード：あり
　ＦＯＶ　ＸＹ（最大撮影領域　ＸＹ）（ｍｍ）：５０．３
　ＦＯＶ　Ｚ（最大撮影領域　Ｚ）（ｍｍ）：４０．０。 [Shooting by X-ray CT]
Image horizontal size (pixel): 512
Image vertical size (pixel): 512
X-ray tube voltage (kV): 50
X-ray tube current (μA): 40
Inch size (inch): 4.0
X-ray filter: None SDD (distance between the focal point of the X-ray source and the X-ray detector) (mm): 700
SRD (distance between the focal point of the X-ray source and the center of rotation of the measurement sample) (mm): 550
Scanning mode 1: CBCT
Scan mode 2: Normal scan Scan angle: Full scan Number of views: 2400
Average number: 5
Smoothing: YZ
Slice thickness (mm): 0.166
BHC data: None Fine mode: Yes FOV XY (maximum shooting area XY) (mm): 50.3
FOV Z (maximum field of view Z) (mm): 40.0.
　次に、Ｘ線ＣＴの撮影データを、三谷商事株式会社製解析ソフト　Ｗｉｎ　ＲＯＯＦを用いて、以下のような手順で解析を行った。 Next, the X-ray CT imaging data was analyzed by the following procedure using the analysis software WinROOF manufactured by Mitani Corporation.
　（１）Ｗｉｎ　ＲＯＯＦを開き、Ｘ線ＣＴにて保存した解析したい画像（Ｊｐｅｇ）を選択する。 (1) Open Win ROOF and select the image (Jpeg) you want to analyze saved by X-ray CT.
　（２）画面上から２値処理、自動２値化、モード法、しきい値（適宜調整する）、実行という流れでクリック（選択）する。 (2) Click (select) from the screen in the flow of binary processing, automatic binarization, mode method, threshold value (adjust appropriately), and execution.
　（３）多角形ＲＯＩを選択し、第１の基材（上方不織布）中の粒子状吸水剤を囲み、粒子状吸水剤面積を計算させる。 (3) Select a polygonal ROI, surround the particulate water absorbent in the first base material (upper non-woven fabric), and have the particle water absorbent area calculated.
　（４）（３）と同様にして、吸水性シート中における粒子状吸水剤の総面積を計算する。 In the same manner as in (4) and (3), the total area of the particulate water absorbing agent in the water absorbing sheet is calculated.
　計算結果から、第１の基材中の粒子状吸水剤の含有割合（％）を下式により計算した。 From the calculation result, the content ratio (%) of the particulate water absorbing agent in the first base material was calculated by the following formula.
　第１の基材中の粒子状吸水剤の含有割合（％）＝第１の基材中の粒子状吸水剤面積（Ｉ）／粒子状吸水剤総面積（ＩＩ）×１００
　すなわち、第１の基材中の粒子状吸水剤の含有割合は、粒子状吸水剤の総面積に対する面積％で表される。なお、吸収される液が導入される側の第１の基材の面上には、粒子状吸水剤は、存在しても数％未満であるため、存在していないとみなすことができる。 Content ratio (%) of particulate water-absorbing agent in the first base material = particle-like water-absorbing agent area (I) in the first base material / total particle-like water-absorbing agent area (II) × 100
That is, the content ratio of the particulate water absorbing agent in the first base material is represented by the area% with respect to the total area of the particulate water absorbing agent. Since the particulate water absorbing agent is less than a few percent on the surface of the first base material on the side where the liquid to be absorbed is introduced, it can be considered that it is not present.
　〔吸水性シートの評価方法〕
　＜逆戻り量（特定戻り量評価）＞
　図６に示されるように縦１０ｃｍ、横４０ｃｍに作製した吸水性シート１０を、縦１４ｃｍ、横４０ｃｍの液体不透過性シート２１で上部に開口部ができるように包んだ。液不透過性シート２１で包んだ吸水性シート１０を平面に置き、その上に液注入筒４１（図７）を図８に示されるように吸水性シート１０の中央に置いた。この状態で、流速７ｍｌ／秒で液投入が可能な漏斗４２を使用して液注入筒４１へ２３℃の０．９重量％塩化ナトリウム水溶液８０ｇを投入した（図９）。なお、この場合、液不透過性シート２１から露出した吸水性シート１０に対して、液が投入されている。液を投入してから１０分後、予め重量を測定した濾紙４３（型式Ｎｏ．２、ＡＤＶＡＮＴＥＣ製；直径１１０ｍｍの円形のもの）２０枚を、吸水性シート１０の中央に載せ、直径１００ｍｍの円形の錘４４（１２００ｇ）をさらに載せて、１分間保持した。１分後、錘４４を除去し、濾紙４３の重量増分から逆戻り量１回目（ｇ）を測定した。錘４４を除去してから１分後、同様の操作（液を投入→投入１０分後、濾紙４３および錘４４（１２００ｇ）を載せて、１分間保持→１分後保持→錘を除去、逆戻り量の測定）を繰り返し、逆戻り量２回目（ｇ）、逆戻り量３回目（ｇ）を測定した。測定した逆戻り量の１回目から３回目までの合計を表１に示した。 [Evaluation method of water-absorbent sheet]
<Reverse amount (specific return amount evaluation)>
As shown in FIG. 6, the water-absorbent sheet 10 produced in a length of 10 cm and a width of 40 cm was wrapped with a liquid-impermeable sheet 21 having a length of 14 cm and a width of 40 cm so as to have an opening at the top. The water-absorbent sheet 10 wrapped with the liquid-impermeable sheet 21 was placed on a flat surface, and the liquid injection cylinder 41 (FIG. 7) was placed on the water-absorbent sheet 10 in the center as shown in FIG. In this state, 80 g of a 0.9 wt% sodium chloride aqueous solution at 23 ° C. was charged into the liquid injection cylinder 41 using a funnel 42 capable of charging the liquid at a flow velocity of 7 ml / sec (FIG. 9). In this case, the liquid is added to the water-absorbent sheet 10 exposed from the liquid-impermeable sheet 21. Ten minutes after the liquid was added, 20 sheets of filter paper 43 (model No. 2, manufactured by ADVANTEC; circular one having a diameter of 110 mm) whose weight was measured in advance were placed on the center of the water-absorbent sheet 10 and a circular shape having a diameter of 100 mm. Weight 44 (1200 g) was further placed and held for 1 minute. After 1 minute, the weight 44 was removed, and the first reversion amount (g) was measured from the weight increment of the filter paper 43. 1 minute after removing the weight 44, the same operation (adding the liquid → 10 minutes after adding the liquid, placing the filter paper 43 and the weight 44 (1200 g), holding for 1 minute → holding after 1 minute → removing the weight, reversing (Measurement of amount) was repeated, and the second reversion amount (g) and the third reversion amount (g) were measured. Table 1 shows the total of the measured reversion amounts from the first to the third.
　＜漏れ量（斜め評価）＞
　漏れ量は、図１０に示す装置を使用して測定した。 <Leakage amount (diagonal evaluation)>
The amount of leakage was measured using the apparatus shown in FIG.
　概略としては、市販の実験設備用の架台６０とパイプ６１とを用いて、アクリル板６３を傾斜させて固定した後、板上に固定した吸水性シートに鉛直上方から漏斗で生理食塩水を投入し、漏れ量を計量する機構である。以下に詳細な仕様を示す。 As a general rule, after the acrylic plate 63 is tilted and fixed using a commercially available pedestal 60 and a pipe 61 for experimental equipment, physiological saline is poured into the water-absorbent sheet fixed on the plate from vertically above with a funnel. It is a mechanism to measure the amount of leakage. Detailed specifications are shown below.
　アクリル板６３は傾斜面方向の長さが４００ｍｍで、架台６０によって水平に対して成す角２０°になるよう固定した。アクリル板６３は幅２００ｍｍ、厚さ３ｍｍであった。アクリル板６３の表面は滑らかなので、板に液体が滞留したり吸収されたりすることはなかった。架台６０を用いて、漏斗６４を傾斜アクリル板６３の鉛直上方に固定した。漏斗６４は７ｍＬ／秒で液が投入されるものを使用した。 The acrylic plate 63 had a length of 400 mm in the direction of the inclined surface, and was fixed by a gantry 60 so as to form an angle of 20 ° with respect to the horizontal. The acrylic plate 63 had a width of 200 mm and a thickness of 3 mm. Since the surface of the acrylic plate 63 is smooth, the liquid did not stay or be absorbed by the plate. The funnel 64 was fixed vertically above the inclined acrylic plate 63 using the gantry 60. The funnel 64 used was one in which the liquid was added at 7 mL / sec.
　アクリル板６３の下部には、金属製トレイ６５を設置されており、漏れとして流れ落ちる試験液をすべて受けとめ、その質量を０．１ｇの精度で記録した。 A metal tray 65 was installed at the bottom of the acrylic plate 63, and received all the test liquid that flowed down as a leak, and recorded its mass with an accuracy of 0.1 g.
　このような装置を用いた傾斜における漏れ試験は以下の手順で行った。図１０に示すように、長さ１００ｍｍ・幅１００ｍｍのサイズに切断した吸水性シート１０の裏面をアクリル板６３上に貼り付けた。 The leak test on the slope using such a device was performed according to the following procedure. As shown in FIG. 10, the back surface of the water-absorbent sheet 10 cut into a size of 100 mm in length and 100 mm in width was attached onto the acrylic plate 63.
　吸水性シートの上端から１．５ｃｍ下方向の箇所に目印をつけ、漏斗の投入口を、目印から鉛直上方距離１５±２ｍｍになるように固定した。 A mark was placed 1.5 cm below the top of the water-absorbent sheet, and the funnel inlet was fixed so that the distance vertically above the mark was 15 ± 2 mm.
　滴下漏斗６４に生理食塩水２０ｍＬを一度に投入した。試験液が吸水性シート６６に吸収されずに傾斜したアクリル板６３を流れ、金属製トレイ６５に入った液量を測定し、面方向の１回目漏れ量（ｍＬ）とし、１０分後、同様に生理食塩水２０ｍＬを投入して、２回目漏れ量を計測した後、さらに１０分後、同様に生理食塩水２０ｍＬを投入して、３回目の漏れ量を計測した。表の漏れ量は１回目から３回目の漏れ量を合計した値である。 20 mL of physiological saline was added to the dropping funnel 64 at a time. The test liquid was not absorbed by the water-absorbent sheet 66 but flowed through the inclined acrylic plate 63, and the amount of liquid that entered the metal tray 65 was measured to obtain the first leakage amount (mL) in the plane direction, and after 10 minutes, the same. After 20 mL of physiological saline was added to and the second leakage amount was measured, 10 minutes later, 20 mL of physiological saline was similarly added and the third leakage amount was measured. The amount of leakage in the table is the total value of the amount of leakage from the first to the third time.
　表１に、実施例１～１０および比較例１～４の吸水性シートの構成および評価結果を表示す。 Table 1 shows the configurations and evaluation results of the water-absorbent sheets of Examples 1 to 10 and Comparative Examples 1 to 4.
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
　以上の結果より、実施例１～１０の吸水性シートは、比較例１～４の吸水性シートと比較して、逆戻り量が顕著に少なく、また、吸水性シートからの漏れも顕著に低下したものであった。 From the above results, the water-absorbent sheets of Examples 1 to 10 had a significantly smaller amount of reversion as compared with the water-absorbent sheets of Comparative Examples 1 to 4, and the leakage from the water-absorbent sheets was also significantly reduced. It was a thing.
　一方、複層構成である比較例１、第１の基材と第２の基材との厚み比が１である比較例２および比較例４では、逆戻り量が著しく増加した。 On the other hand, in Comparative Example 1 having a multi-layer structure, Comparative Example 2 and Comparative Example 4 in which the thickness ratio of the first base material to the second base material was 1, the amount of reversion was significantly increased.
　［実施例１１］
　縦２４ｃｍ、横４０ｃｍに切断した、ポリオレフィン繊維を主成分とする、厚み０．１ｍｍのスパンボンド不織布（ラッピングシートに相当）を敷いておき、その中央に、縦１０ｃｍ、横４０ｃｍに切断した、ポリオレフィン繊維を主成分とする、厚み１．４ｍｍの起毛処理したエアスルー不織布Ａ（第１の基材に相当）を載せ、不織布Ａの起毛処理した表面に、粒子状吸水剤（２）を、９．０ｇ（散布量：２２５ｇ／ｍ２）均一に散布した。なお、不織布Ａの起毛処理は後述する方法に従って行った。 [Example 11]
A spunbonded non-woven fabric (corresponding to a wrapping sheet) having a thickness of 0.1 mm and mainly composed of polyolefin fiber, which was cut into a length of 24 cm and a width of 40 cm, was laid, and a polyolefin cut into a length of 10 cm and a width of 40 cm was laid in the center thereof. 9. A raised air-through non-woven fabric A (corresponding to the first base material) having a thickness of 1.4 mm and containing fibers as a main component is placed on the raised surface of the non-woven fabric A, and the particulate water absorbent (2) is applied. 0 g (spray amount: 225 g / m 2 ) was uniformly sprayed. The brushing treatment of the non-woven fabric A was performed according to the method described later.
　次に、縦１０ｃｍ、横４０ｃｍに切断した不織布Ｅ（パルプ繊維を主成分とする。厚み０．４ｍｍ。エアレイド法で作成されたもの。第２の基材に相当する。目付量：４７ｇ／ｍ２）の表面に、１３５℃に加熱して液状にしたホットメルト接着剤（ＪａｏｕｒＭｅｌｔ３８８９Ｕ、ＪＡＯＵＲ　ＨＯＴ　ＭＥＬＴ　ＡＤＨＥＳＩＶＥ社製、主成分：スチレンブロック共重合体、炭化水素樹脂、白色鉱油）を、０．８ｇ均一に散布した（散布量：２０．０ｇ／ｍ２）。その後、不織布Ａの粒子状吸水剤を散布した面と不織布Ｅの接着剤を散布した面が対合するように（接触するように）重ね、加圧圧着し、中間体シートＹを得た。 Next, the non-woven fabric E cut into a length of 10 cm and a width of 40 cm (mainly composed of pulp fiber. Thickness 0.4 mm. Prepared by the air-laid method. Corresponds to the second base material. Grain amount: 47 g / m 2 ) On the surface, 0.8 g of a hot melt adhesive (manufactured by Jaour Melt 3889U, JAOUR HOT MELT ADHESIVE, main component: styrene block copolymer, hydrocarbon resin, white mineral oil) liquefied by heating to 135 ° C. It was sprayed evenly (spray amount: 20.0 g / m 2 ). Then, the surface of the nonwoven fabric A on which the particulate water absorbing agent was sprayed and the surface of the nonwoven fabric E on which the adhesive was sprayed were overlapped so as to face each other (contacting each other) and pressure-bonded to obtain an intermediate sheet Y.
　上記中間体シートＹの不織布Ｅの表面に、１３５℃に加熱して液状にしたホットメルト接着剤（ＪａｏｕｒＭｅｌｔ３８８９Ｕ、ＪＡＯＵＲ　ＨＯＴ　ＭＥＬＴ　ＡＤＨＥＳＩＶＥ社製、主成分：スチレンブロック共重合体、炭化水素樹脂、白色鉱油）０．３ｇを散布した（散布量：７．５ｇ／ｍ２）。次に、上記スパンボンド不織布の余った部分を折り曲げて、上記中間体シートＹの不織布Ｅの表面と上記スパンボンド不織布が接触するように包み、上下が逆になるようひっくり返した後、加圧圧着して、吸水性シート（２１）を得た。 On the surface of the non-woven fabric E of the intermediate sheet Y, a hot melt adhesive (manufactured by Jaour Melt 3889U, JAOUR HOT MELT ADHESIVE) heated to 135 ° C., main component: styrene block copolymer, hydrocarbon resin, white mineral oil ) 0.3 g was sprayed (spray amount: 7.5 g / m 2 ). Next, the excess portion of the spunbonded non-woven fabric is bent, wrapped so that the surface of the non-woven fabric E of the intermediate sheet Y and the spunbonded non-woven fabric are in contact with each other, turned upside down, and then pressurized. It was worn to obtain a water-absorbent sheet (21).
　［実施例１２］
　粒子状吸水剤の散布量を１２．０ｇ（散布量：３００ｇ／ｍ２）にした以外は、実施例１と同様にして、吸水性シート（２２）を得た。 [Example 12]
A water-absorbing sheet (22) was obtained in the same manner as in Example 1 except that the spraying amount of the particulate water-absorbing agent was 12.0 g (spraying amount: 300 g / m 2).
　［実施例１３］
　起毛処理した不織布Ａを使用する代わりに、起毛処理していない不織布Ａを使用した以外は、実施例２と同様にして、吸水性シート（２３）を得た。 [Example 13]
A water-absorbent sheet (23) was obtained in the same manner as in Example 2 except that the non-woven fabric A which had not been brushed was used instead of the non-woven fabric A which had been brushed.
　［実施例１４］
　不織布Ｅに対して散布する接着剤をスチレンブタジエンゴムを含む接着剤（スプレーのり７７、スリーエムジャパン株式会社製）０．８ｇ（散布量：２０．０ｇ／ｍ２）にした以外は、実施例１と同様にして、吸水性シート（２４）を得た。 [Example 14]
Example 1 except that the adhesive to be sprayed on the non-woven fabric E was 0.8 g (spray amount: 20.0 g / m 2) of an adhesive containing styrene-butadiene rubber (spray glue 77, manufactured by 3M Japan Ltd.). In the same manner as above, a water-absorbent sheet (24) was obtained.
　［実施例１５］
　下記の製造方法により得られた粒子状吸水剤（５）を使用した以外は、実施例１２と同様にして、吸水性シート（２５）を得た。 [Example 15]
A water-absorbing sheet (25) was obtained in the same manner as in Example 12 except that the particulate water-absorbing agent (5) obtained by the following production method was used.
　＜粒子状吸水剤（５）＞
　上記アクリル酸の製造例で得られたアクリル酸、該アクリル酸を用いて上記アクリル酸ナトリウム水溶液の製法で得られたアクリル酸ナトリウム水溶液、および脱イオン水を混合して得られた７５モル％の中和率を有するアクリル酸ナトリウムの水溶液５５００ｇ（単量体濃度３８質量％）に、ポリエチレングリコールジアクリレート（エチレンオキシドの平均付加モル数９）５．０３ｇを溶解し反応液とした。次いで、シグマ型羽根を２本有する内容積１０Ｌのジャケット付きステンレス製双腕型ニーダーに蓋を付けて形成した反応器に、上記反応液を供給し、反応液を３０℃に保ちながら系を窒素ガス置換し、反応液中の溶存酸素を除去した。続いて、反応液を撹拌しながら、過硫酸ナトリウムの１０質量％水溶液３０．６８ｇ及びＬ－アスコルビン酸の１質量％水溶液３７．７６ｇを添加したところ、およそ１分後に重合が開始した。重合を開始して４０分後に含水ゲル状重合体を取り出した。得られた含水ゲル状重合体は約２～４ｍｍの粒子に細分化されていた。この細分化された含水ゲル状重合体を５０メッシュ（目の大きさ３００μｍ）の金網上に広げ、１７５℃で６５分間熱風乾燥した。次いで、乾燥物をロールミルを用いて粉砕し、さらに目開き６００μｍの金網で分級、調合することにより、平均粒子径３８０μｍの不定形破砕状の吸水性樹脂（５－１）を得た。 <Particular water absorbent (5)>
75 mol% obtained by mixing the acrylic acid obtained in the above production example of acrylic acid, the aqueous sodium acrylate solution obtained by the above method for producing an aqueous sodium acrylate solution using the acrylic acid, and deionized water. 5.03 g of polyethylene glycol diacrylate (average number of moles of ethylene oxide added 9) was dissolved in 5500 g (monomer concentration 38% by mass) of an aqueous solution of sodium acrylate having a neutralization rate to prepare a reaction solution. Next, the above reaction solution was supplied to a reactor formed by attaching a lid to a stainless steel double-armed kneader with an internal volume of 10 L having two sigma type blades, and the system was nitrogenized while keeping the reaction solution at 30 ° C. Gas replacement was performed to remove dissolved oxygen in the reaction solution. Subsequently, 30.68 g of a 10 mass% aqueous solution of sodium persulfate and 37.76 g of a 1 mass% aqueous solution of L-ascorbic acid were added while stirring the reaction solution, and the polymerization started after about 1 minute. 40 minutes after the start of the polymerization, the hydrogel polymer was taken out. The obtained hydrogel polymer was subdivided into particles having a size of about 2 to 4 mm. The subdivided hydrogel polymer was spread on a wire mesh of 50 mesh (mesh size 300 μm) and dried with hot air at 175 ° C. for 65 minutes. Next, the dried product was pulverized using a roll mill, further classified and blended with a wire mesh having a mesh size of 600 μm to obtain an amorphous crushed water-absorbent resin (5-1) having an average particle size of 380 μm.
　得られた吸水性樹脂（５－１）１００質量部に、エチレングリコールジグリシジルエーテル０．０３質量部、１，４－ブタンジオール０．３質量部、プロピレングリコール０．５質量部、水３．０質量部からなる表面架橋剤水溶液３．８３質量部を噴霧混合した。上記の混合物を、パドル型混合加熱処理機を用いて、熱媒温度２１０℃で４０分間加熱処理して表面架橋された吸水性樹脂（５－２）を得た。得られた表面架橋された吸水性樹脂（５－２）１００質量部に、水１．０質量部を噴霧混合して、密閉容器内で６０℃で１時間硬化させた後、目開き７１０μｍのふるいを通過させて吸水性樹脂（５－３）を得た。吸水性樹脂（５－３）にＡｅｒｏｓｉｌ２００（親水性アモルファスシリカ、日本アエロジル社製）を０．３質量部添加して混合することにより得た吸水性樹脂を粒子状吸水剤（５）とした。 In 100 parts by mass of the obtained water-absorbent resin (5-1), 0.03 parts by mass of ethylene glycol diglycidyl ether, 0.3 parts by mass of 1,4-butanediol, 0.5 parts by mass of propylene glycol, and water 3. 3.83 parts by mass of a surface cross-linking agent aqueous solution consisting of 0 parts by mass was spray-mixed. The above mixture was heat-treated at a heat medium temperature of 210 ° C. for 40 minutes using a paddle-type mixing heat treatment machine to obtain a surface-crosslinked water-absorbent resin (5-2). 1.0 part by mass of water was spray-mixed with 100 parts by mass of the obtained surface-crosslinked water-absorbent resin (5-2) and cured at 60 ° C. for 1 hour in a closed container, and then the opening was 710 μm. A water-absorbent resin (5-3) was obtained by passing through a sieve. The water-absorbent resin obtained by adding 0.3 parts by mass of Aerosil 200 (hydrophilic amorphous silica, manufactured by Nippon Aerosil Co., Ltd.) to the water-absorbent resin (5-3) and mixing them was used as a particulate water-absorbent resin (5).
　［実施例１６］
　下記の製造方法により得られた粒子状吸水剤（６）を使用した以外は、実施例１２と同様にして、吸水性シート（２６）を得た。 [Example 16]
A water-absorbing sheet (26) was obtained in the same manner as in Example 12 except that the particulate water-absorbing agent (6) obtained by the following production method was used.
　＜粒子状吸水剤（６）＞
　上記アクリル酸の製造例で得られたアクリル酸、該アクリル酸を用いて上記アクリル酸ナトリウム水溶液の製法で得られたアクリル酸ナトリウム水溶液、および脱イオン水を混合して得られた７５モル％の中和率を有するアクリル酸ナトリウムの水溶液５５００ｇ（単量体濃度３６．０質量％）に、ポリエチレングリコールジアクリレート（エチレンオキシドの平均付加モル数９）４．１１ｇを溶解し反応液とした。次いで、シグマ型羽根を２本有する内容積１０Ｌのジャケット付きステンレス製双腕型ニーダーに蓋を付けて形成した反応器に、上記反応液を供給し、反応液を３０℃に保ちながら系を窒素ガス置換し、反応液中の溶存酸素を除去した。続いて、反応液を撹拌しながら、過硫酸ナトリウムの１０質量％水溶液２８．６６ｇおよびＬ－アスコルビン酸の１質量％水溶液３５．２８ｇを添加したところ、およそ１分後に重合が開始した。 <Particular water absorbent (6)>
75 mol% obtained by mixing the acrylic acid obtained in the above production example of acrylic acid, the aqueous sodium acrylate solution obtained by the above method for producing an aqueous sodium acrylate solution using the acrylic acid, and deionized water. 4.11 g of polyethylene glycol diacrylate (average number of moles of ethylene oxide added 9) was dissolved in 5500 g (monomer concentration 36.0% by mass) of an aqueous solution of sodium acrylate having a neutralization rate to prepare a reaction solution. Next, the above reaction solution was supplied to a reactor formed by attaching a lid to a stainless steel double-armed kneader with an internal volume of 10 L having two sigma type blades, and the system was nitrogenized while keeping the reaction solution at 30 ° C. Gas replacement was performed to remove dissolved oxygen in the reaction solution. Subsequently, 28.66 g of a 10 mass% aqueous solution of sodium persulfate and 35.28 g of a 1 mass% aqueous solution of L-ascorbic acid were added while stirring the reaction solution, and the polymerization started after about 1 minute.
　重合を開始して４０分後、１５０μｍ以下の吸水性樹脂微粉末を１８１．５ｇ添加したうえで、ニーダーのブレードを高速回転（１３０ｒｐｍ）で１０分間ゲル解砕してから含水ゲル状重合体を取り出した。得られた含水ゲル状重合体は約１～２ｍｍの粒子に細分化されていた。この細分化された含水ゲル状重合体を５０メッシュ（目の大きさ３００μｍ）の金網上に広げ、１７５℃で６５分間熱風乾燥した。次いで、乾燥物をロールミルを用いて粉砕し、さらに目開き６００μｍの金網で分級、調合することにより、平均粒子径３５０μｍの不定形破砕状の吸水性樹脂（６－１）を得た。 Forty minutes after the start of the polymerization, 181.5 g of a water-absorbent resin fine powder of 150 μm or less was added, and the kneader blade was gel-crushed at a high speed rotation (130 rpm) for 10 minutes, and then the hydrogel polymer was prepared. I took it out. The obtained hydrogel polymer was subdivided into particles having a size of about 1 to 2 mm. The subdivided hydrogel polymer was spread on a wire mesh of 50 mesh (mesh size 300 μm) and dried with hot air at 175 ° C. for 65 minutes. Next, the dried product was pulverized using a roll mill, further classified and blended with a wire mesh having a mesh size of 600 μm to obtain an amorphous crushed water-absorbent resin (6-1) having an average particle diameter of 350 μm.
　得られた吸水性樹脂（６－１）１００質量部に、エチレングリコールジグリシジルエーテル０．０３質量部、プロピレングリコール１．０質量部、水３．０質量部からなる表面架橋剤水溶液４．０３質量部を噴霧混合した。上記の混合物を、パドル型混合加熱処理機を用いて、熱媒温度１００℃で４０分間加熱処理して表面架橋された吸水性樹脂（６－２）を得た。得られた表面架橋された吸水性樹脂（６－２）１００質量部に、水３．０質量部を噴霧混合して、密閉容器内で６０℃で１時間硬化させた後、目開き７１０μｍのふるいを通過させて吸水性樹脂（６－３）を得た。吸水性樹脂（６－３）にＡｅｒｏｓｉｌ９０Ｇ（親水性アモルファスシリカ、日本アエロジル社製）を０．３質量部添加して混合することにより得た吸水性樹脂を粒子状吸水剤（６）とした。 A surface cross-linking agent aqueous solution 4.03 consisting of 0.03 parts by mass of ethylene glycol diglycidyl ether, 1.0 part by mass of propylene glycol, and 3.0 parts by mass of water in 100 parts by mass of the obtained water-absorbent resin (6-1). The parts by mass were spray-mixed. The above mixture was heat-treated at a heat medium temperature of 100 ° C. for 40 minutes using a paddle-type mixing heat treatment machine to obtain a surface-crosslinked water-absorbent resin (6-2). 3.0 parts by mass of water was spray-mixed with 100 parts by mass of the obtained surface-crosslinked water-absorbent resin (6-2) and cured at 60 ° C. for 1 hour in a closed container, and then the opening was 710 μm. A water-absorbent resin (6-3) was obtained by passing through a sieve. The water-absorbent resin obtained by adding 0.3 parts by mass of Aerosil 90G (hydrophilic amorphous silica, manufactured by Nippon Aerosil Co., Ltd.) to the water-absorbent resin (6-3) and mixing them was used as a particulate water-absorbent resin (6).
　［実施例１７］
　下記の製造方法により得られた粒子状吸水剤（７）を使用した以外は、実施例１２と同様にして、吸水性シート（２７）を得た。 [Example 17]
A water-absorbing sheet (27) was obtained in the same manner as in Example 12 except that the particulate water-absorbing agent (7) obtained by the following production method was used.
　＜粒子状吸水剤（７）＞
容量２リットルのポリプロピレン製容器に、アクリル酸３５１．７ｇ、内部架橋剤としてポリエチレングリコールジアクリレート（分子量５２３）０．８６０ｇ（カルボキシル基含有不飽和単量体に対して０．０３４モル％）、１．０重量％のジエチレントリアミン５酢酸・３ナトリウム（ＤＴＰＡ・３Ｎａ）水溶液２．１５ｇ、４８．５重量％の水酸化ナトリウム水溶液１４９．０ｇ、および脱イオン水（イオン交換水）３３６．２ｇを投入し混合させて、単量体水溶液（ａ’）を作製した。 <Particular water absorbent (7)>
In a polypropylene container with a capacity of 2 liters, 351.7 g of acrylic acid, 0.860 g of polyethylene glycol diacrylate (molecular weight 523) as an internal cross-linking agent (0.034 mol% with respect to a carboxyl group-containing unsaturated monomer), 1 Add 2.15 g of a 0.0 wt% diethylenetriamine-5 acetic acid / 3 sodium (DTPA / 3Na) aqueous solution, 149.0 g of a 48.5 wt% sodium hydroxide aqueous solution, and 336.2 g of deionized water (ion-exchanged water). The mixture was mixed to prepare a monomer aqueous solution (a').
　次に、上記単量体水溶液（ａ’）を攪拌しながら冷却した。液温が４０．０℃となった時点で、４０℃に調温した４８．５重量％の水酸化ナトリウム水溶液１４４．８ｇを加え、混合することで単量体水溶液（ａ）を作製した。このとき、該単量体水溶液（ａ）の温度は、作製直後の２段目の中和熱によって７８．２℃まで上昇した。４８．５重量％の水酸化ナトリウム水溶液を混合し始めた直後は、析出物が観察されたが、次第に溶解し透明な均一溶液となった。 Next, the monomer aqueous solution (a') was cooled with stirring. When the liquid temperature reached 40.0 ° C., 144.8 g of a 48.5% by weight sodium hydroxide aqueous solution adjusted to 40 ° C. was added and mixed to prepare a monomer aqueous solution (a). At this time, the temperature of the monomer aqueous solution (a) was raised to 78.2 ° C. by the heat of neutralization in the second stage immediately after the production. Immediately after starting to mix the 48.5% by weight aqueous sodium hydroxide solution, precipitates were observed, but they gradually dissolved to become a transparent uniform solution.
　次に、攪拌状態の上記単量体水溶液（ａ）に４．０重量％の過硫酸ナトリウム水溶液１５．４９ｇを加えた後、直ちにステンレス製バット型容器（底面３４０×３４０ｍｍ、高さ２５ｍｍ、内面；テフロン（登録商標）コーティング）に大気開放系で注いだ。なお、２段目の中和開始からバット型容器に単量体水溶液（ａ）を注ぎ込むまでの時間は５５秒間とし、該バット型容器はホットプレート（ＮＥＯ　ＨＯＴＰＬＡＴＥ　ＨＩ－１０００／株式会社井内盛栄堂社）を用いて、表面温度が４０℃となるまで加熱した。 Next, after adding 15.49 g of a 4.0 wt% sodium persulfate aqueous solution to the agitated monomer aqueous solution (a), a stainless steel bat-shaped container (bottom surface 340 × 340 mm, height 25 mm, inner surface) was immediately added. Pour into Teflon® coating) in an open system. The time from the start of neutralization in the second stage to the pouring of the monomer aqueous solution (a) into the vat-type container was 55 seconds, and the vat-type container was a hot plate (NEO HOTPLATE HI-1000 / Inuchi Seieidou Co., Ltd.). The company) was used to heat the surface until the surface temperature reached 40 ° C.
　上記単量体水溶液（ａ）がバット型容器に注がれてから６０秒経過後に重合反応が開始した。該重合反応は、水蒸気を発生しながら四方八方に膨脹発泡して進行した後、バット型容器よりも若干大きなサイズまで収縮した。重合反応の開始から３分経過後に、含水ゲル状架橋重合体（以下、「含水ゲル」と称する）（７－１）を取り出した。なお、これら一連の操作は、大気開放系で行った。 The polymerization reaction started 60 seconds after the above-mentioned monomer aqueous solution (a) was poured into the vat-shaped container. The polymerization reaction proceeded by expanding and foaming in all directions while generating water vapor, and then contracted to a size slightly larger than that of the vat-shaped container. After 3 minutes from the start of the polymerization reaction, a hydrogel-like crosslinked polymer (hereinafter referred to as “hydrogen gel”) (7-1) was taken out. These series of operations were performed in an open system to the atmosphere.
　上記重合反応で得られた含水ゲル（７－１）を短冊状に切断し、スクリュー押出機に供給してゲル粉砕を行い、粒子状含水ゲル（７－２）を得た。なお、スクリュー押出機には、先端部に直径１００ｍｍ、孔径１１．０ｍｍ、孔数４０個、開孔率　６２．５％、厚み１０ｍｍの多孔板が備えられ、スクリュー軸の外径は８６ｍｍであった。 The hydrogel (7-1) obtained by the above polymerization reaction was cut into strips, supplied to a screw extruder and pulverized to obtain a particulate hydrogel (7-2). The screw extruder is provided with a perforated plate having a diameter of 100 mm, a hole diameter of 11.0 mm, a number of holes of 40, an aperture ratio of 62.5%, and a thickness of 10 mm at the tip, and the outer diameter of the screw shaft is 86 mm. It was.
　上記ゲル粉砕は、上記スクリュー押出機のスクリュー軸の回転数を１３０ｒｐｍとした状態で、上記短冊状の含水ゲル（７－１）と水蒸気とをそれぞれ別の供給口から同時に供給することで行われた。なお、該含水ゲル（７－１）の供給量は毎分４６４０ｇ、水蒸気の供給量は毎分８３ｇであった。 The gel crushing is performed by simultaneously supplying the strip-shaped hydrogel (7-1) and water vapor from different supply ports in a state where the rotation speed of the screw shaft of the screw extruder is 130 rpm. It was. The supply amount of the hydrogel (7-1) was 4640 g / min, and the supply amount of water vapor was 83 g / min.
　この粒子状含水ゲル（７－２）を５０メッシュの金網上に広げ、１９０℃で３０分間熱風乾燥を行い、乾燥物をロールミル（ＷＭＬ型ロール粉砕機／有限会社井ノ口技研社）を用いて粉砕し、さらに目開き８５０μｍ、６００μｍ、５００μｍ、３００μｍ、１５０μｍを有するＪＩＳ篩で篩い分けた後調合することにより、重量平均粒子径（Ｄ５０）３０５μｍ、粒度分布の対数標準偏差（σζ）０．３５の不定形破砕状の前駆体吸水性樹脂（Ａ）を得た。前駆体吸水性樹脂（Ａ）の遠心分離機保持容量（ＣＲＣ）は４８．４（ｇ／ｇ）であった。 This particulate hydrogel (7-2) is spread on a 50-mesh wire mesh, dried with hot air at 190 ° C. for 30 minutes, and the dried product is crushed using a roll mill (WML type roll crusher / Inoguchi Giken Co., Ltd.). Then, by further sieving with a JIS sieve having a mesh size of 850 μm, 600 μm, 500 μm, 300 μm, and 150 μm and then preparing the mixture, the weight average particle size (D50) is 305 μm and the logarithmic standard deviation (σζ) of the particle size distribution is 0.35. An amorphous crushed precursor water-absorbent resin (A) was obtained. The centrifuge holding capacity (CRC) of the precursor water-absorbent resin (A) was 48.4 (g / g).
　前駆体吸水性樹脂（Ａ）１００重量部に対して、エチレングリコールジグリシジルエーテル０．０３重量部、プロピレングリコール１．５重量部および脱イオン水３．５重量部からなる表面架橋剤溶液を均一に混合し、１００℃で３０分間程度、得られる吸水性樹脂（１）のＣＲＣが約３５［ｇ／ｇ］となるように加熱処理を行った。その後冷却を行い、吸水性樹脂１００重量部に対して、脱イオン水１重量部、ジエチレントリアミン５酢酸・３ナトリウム（ＤＴＰＡ・３Ｎａ）０．０５重量部からなる水溶液を均一に混合した。６０℃で１時間乾燥した後、目開き８５０μｍのＪＩＳ標準篩を通過させ、二酸化ケイ素（商品名：レオロシールＱＳ－２０、株式会社トクヤマ製）０．３重量部を混合した。混合は吸水性樹脂３０ｇを容量２２５ｍＬのマヨネーズ瓶に二酸化ケイ素と共に入れ、ターブラ・シェーカー・ミキサーＴ２Ｆ型（株式会社シンマルエンタープライゼス製）の振動によって６０分間混合し、吸水性樹脂粒子（７）を得た。 A surface cross-linking agent solution consisting of 0.03 parts by weight of ethylene glycol diglycidyl ether, 1.5 parts by weight of propylene glycol and 3.5 parts by weight of deionized water was uniformly applied to 100 parts by weight of the precursor water-absorbent resin (A). Was mixed with and heat-treated at 100 ° C. for about 30 minutes so that the CRC of the obtained water-absorbent resin (1) was about 35 [g / g]. After that, cooling was performed, and an aqueous solution consisting of 1 part by weight of deionized water and 0.05 part by weight of diethylenetriamine-5 acetic acid / 3 sodium (DTPA / 3Na) was uniformly mixed with 100 parts by weight of the water-absorbent resin. After drying at 60 ° C. for 1 hour, the mixture was passed through a JIS standard sieve having an opening of 850 μm, and 0.3 parts by weight of silicon dioxide (trade name: Leoloseal QS-20, manufactured by Tokuyama Corporation) was mixed. For mixing, 30 g of water-absorbent resin was put into a mayonnaise bottle having a capacity of 225 mL together with silicon dioxide, and the mixture was mixed for 60 minutes by vibration of a Tarbra shaker mixer T2F type (manufactured by Simmal Enterprises Co., Ltd.), and the water-absorbent resin particles (7) were mixed. Obtained.
　［実施例１８］
　縦２４ｃｍ、横４０ｃｍに切断した、ポリオレフィン繊維を主成分とする、厚み０．１ｍｍのスパンボンド不織布（ラッピングシートに相当）を敷いておき、その中央に、縦１０ｃｍ、横４０ｃｍに切断した、ポリオレフィン繊維を主成分とする、厚み１．４ｍｍの起毛処理したエアスルー不織布Ａ（第１の基材に相当）を載せ、不織布Ａの起毛処理した表面に、１３５℃に加熱して液状にしたホットメルト接着剤（ＪａｏｕｒＭｅｌｔ３８８９Ｕ、ＪＡＯＵＲ　ＨＯＴ　ＭＥＬＴ　ＡＤＨＥＳＩＶＥ社製、主成分：スチレンブロック共重合体、炭化水素樹脂、白色鉱油）を、０．８ｇ均一に散布（散布量：２０．０ｇ／ｍ２）し、その後、不織布Ａの起毛し接着剤の付着した表面に粒子状吸水剤（２）を、１２．０ｇ（散布量：３００ｇ／ｍ２）均一に散布した。 [Example 18]
A 0.1 mm thick spunbonded non-woven fabric (corresponding to a wrapping sheet) mainly composed of polyolefin fiber cut into a length of 24 cm and a width of 40 cm is laid, and a polyolefin cut into a length of 10 cm and a width of 40 cm is laid in the center thereof. A 1.4 mm thick brushed air-through non-woven fabric A (corresponding to the first base material) containing fibers as the main component is placed on the brushed surface of the non-woven fabric A and heated to 135 ° C. to make it liquid. 0.8 g of an adhesive (Jaour Melt 3889U, manufactured by JAOUR HOT MELT ADHESIVE, main component: styrene block copolymer, hydrocarbon resin, white mineral oil) was uniformly sprayed (spray amount: 20.0 g / m 2 ), and then. , 12.0 g (spray amount: 300 g / m 2 ) of the particulate water absorbent (2) was uniformly sprayed on the surface of the non-woven fabric A to which the brushed adhesive was attached.
　次に、縦１０ｃｍ、横４０ｃｍに切断した不織布Ｅ（パルプ繊維を主成分とする。厚み０．４ｍｍ。エアレイド法で作成されたもの。第２の基材に相当する。目付量：４７ｇ／ｍ２）と不織布Ａの接着剤及び粒子状吸水剤を散布した面が対合するように（接触するように）重ね、加圧圧着し、中間体シートＹを得た。 Next, the non-woven fabric E cut into a length of 10 cm and a width of 40 cm (mainly composed of pulp fiber. Thickness 0.4 mm. Made by the airlaid method. Corresponds to the second base material. Grain amount: 47 g / m 2 ) and the surfaces sprayed with the adhesive and the particulate water absorbent of the non-woven fabric A were overlapped so as to face each other (contact each other) and pressure-bonded to obtain an intermediate sheet Y.
　上記中間体シートＹの不織布Ｅの表面に、１３５℃に加熱して液状にしたホットメルト接着剤（ＪａｏｕｒＭｅｌｔ３８８９Ｕ、ＪＡＯＵＲ　ＨＯＴ　ＭＥＬＴ　ＡＤＨＥＳＩＶＥ社製、主成分：スチレンブロック共重合体、炭化水素樹脂、白色鉱油）０．３ｇを均一に散布した（散布量：７．５ｇ／ｍ２）。次に、上記スパンボンド不織布の余った部分を折り曲げて、上記中間体シートＹの不織布Ｅの表面と上記スパンボンド不織布が接触するように包み、上下が逆になるようひっくり返した後、加圧圧着して、吸水性シート（２８）を得た。 Hot melt adhesive (manufactured by Jaour Melt 3889U, JAOUR HOT MELT ADHESIVE), which was liquefied by heating to 135 ° C. on the surface of the non-woven fabric E of the intermediate sheet Y, main component: styrene block copolymer, hydrocarbon resin, white mineral oil. ) 0.3 g was uniformly sprayed (spray amount: 7.5 g / m 2 ). Next, the excess portion of the spunbonded non-woven fabric is bent, wrapped so that the surface of the non-woven fabric E of the intermediate sheet Y and the spunbonded non-woven fabric are in contact with each other, turned upside down, and then pressurized. It was worn to obtain a water-absorbent sheet (28).
　＜起毛処理＞
　水平で平滑な面を有する机に不織布を静置し、不織布の長軸方向の両端に１０ｋｇの錘を乗せ、不織布を固定する。不織布の長軸に対して垂直にブラシ（長さ：１００ｍｍ、毛丈：２５ｍｍ、ブラシの材質：ポリブチレンテレフタレート樹脂、ブラシ径：０．２ｍｍ）を上方から構え、不織布表面に向かって鉛直下向きに降ろし、そのままブラシの先端で不織布を押し込みながら、机の面に接するまで差し込む。その後、ブラシを不織布の長軸方向に対して荷重をかけずに所望の長さまで水平に移動させる。ブラシと錘を取り外し、ブラシを移動させた部分の不織布を切り取って、起毛した不織布を得る。 <Brushing treatment>
The non-woven fabric is placed on a desk having a horizontal and smooth surface, and 10 kg weights are placed on both ends of the non-woven fabric in the long axis direction to fix the non-woven fabric. Hold the brush (length: 100 mm, hair length: 25 mm, brush material: polybutylene terephthalate resin, brush diameter: 0.2 mm) perpendicular to the long axis of the non-woven fabric from above, and point vertically downward toward the surface of the non-woven fabric. Lower it and push the non-woven fabric with the tip of the brush as it is, and insert it until it touches the surface of the desk. Then, the brush is horizontally moved to a desired length without applying a load in the longitudinal direction of the non-woven fabric. The brush and weight are removed, and the non-woven fabric in the portion where the brush is moved is cut off to obtain a brushed non-woven fabric.
　＜起毛面積率測定方法＞
起毛処理を施した不織布を２０ｃｍ×１０ｃｍのサイズに切り取り、その不織布の下側に、幅３ｃｍの平滑なプラスチックプレートを、不織布の長軸に対して垂直に差し込む（図１１（ａ）参照）。次に、不織布を鉛直上向きに１０ｃｍ程度掬い上げ、プラスチックプレートを水平に保つ。ぶら下がった不織布の長軸の両端を、重量が７０ｇ、挟み口が１０ｃｍ以上あるクリップで下方から挟む（図１１（ｂ）参照）。不織布の短軸に垂直な方向から、プラスチックプレート上に引き伸ばされた不織布上面の写真を撮影する（図１１（ｂ）の矢印の方向から撮影）。 <Measuring method of raised area ratio>
The brushed non-woven fabric is cut into a size of 20 cm × 10 cm, and a smooth plastic plate having a width of 3 cm is inserted under the non-woven fabric perpendicularly to the long axis of the non-woven fabric (see FIG. 11 (a)). Next, scoop up the non-woven fabric vertically upward by about 10 cm to keep the plastic plate horizontal. Both ends of the long shaft of the hanging non-woven fabric are clipped from below with clips having a weight of 70 g and a pinch opening of 10 cm or more (see FIG. 11B). A photograph of the upper surface of the non-woven fabric stretched on the plastic plate is taken from the direction perpendicular to the short axis of the non-woven fabric (taken from the direction of the arrow in FIG. 11B).
　撮影した写真を画像解析ソフトＷｉｎＲｏｏｆ（ｖｅｒ．６．１）に取り込み、タブの「画像処理」より「モノクロ画像処理」する。その後、図１１（ｃ）のように長方形ＲＯＩによって、起毛している範囲（不織布表面から５ｍｍ上の範囲）を選択し、タブ「２値処理」から「自動２値化」を選択し、起毛した繊維だけを選択できるようにしきい値を調整する。タブ「計測」から「総面積・個数」の「面積率」を選択して実行し、不織布の起毛面積率を算出した。 Import the taken photo into the image analysis software WinRoof (ver.6.1) and perform "monochrome image processing" from "image processing" on the tab. After that, as shown in FIG. 11C, select the brushed area (the range 5 mm above the non-woven fabric surface) by the rectangular ROI, select the tab "Binarization" and select "Automatic binarization", and brush. Adjust the threshold so that only the selected fibers can be selected. From the tab "Measurement", "Area ratio" of "Total area / number" was selected and executed, and the raised area ratio of the non-woven fabric was calculated.
　＜加圧特定戻り量評価＞
　図６に示されるように縦１０ｃｍ、横４０ｃｍに作製した吸水性シート１０を、縦１４ｃｍ、横４０ｃｍの液体不透過性シート２１で上部に開口部ができるように包んだ。液不透過性シート２１で包んだ吸水性シート１０を平面に置き、その上に液投入筒４５（内径２６ｍｍ、外径３０ｍｍ、長さ１５０ｍｍ、重さ３４ｇのプラスチック筒に対し、内径３０ｍｍ、外径６０ｍｍ、長さ６２ｍｍ、重さ１０３０ｇの錘を取り付けたもの、図１２）を図１３に示されるように吸水性シート１０の中央に置いた。この状態で、流速７ｍｌ／秒で液投入が可能な漏斗４２を使用して液注入筒４５へ、２３℃の０．９重量％塩化ナトリウム及び０．００２重量％食用青色１号（東京化成工業株式会社）を含む水溶液８０ｇを投入した（図１４）。水溶液を投入した瞬間から、液投入筒４５内の水溶液が吸水性シート１０に全て吸水されるまでの時間を計測した。なお、この場合、液不透過性シート２１から露出した吸水性シート１０に対して、液が投入されている。液を投入してから１０分後、予め重量を測定した濾紙４３（型式Ｎｏ．２、ＡＤＶＡＮＴＥＣ製；直径１１０ｍｍの円形のもの）２０枚を、吸水性シート１０の中央に載せ、直径１００ｍｍの円形の錘４４（１２００ｇ）をさらに載せて、１分間保持した。１分後、錘４４を除去し、濾紙４３の重量増分から逆戻り量１回目（ｇ）を測定した。錘４４を除去してから１分後、同様の操作（液を投入→液の吸水時間を計測→投入１０分後、濾紙４３および錘４４（１２００ｇ）を載せて、１分間保持→１分後保持→錘を除去、逆戻り量の測定）を繰り返し、逆戻り量２回目（ｇ）、逆戻り量３回目（ｇ）を測定した。測定した吸水時間および逆戻り量の１回目から３回目までの合計を表１に示した。 <Evaluation of specific return amount under pressure>
As shown in FIG. 6, the water-absorbent sheet 10 produced in a length of 10 cm and a width of 40 cm was wrapped with a liquid-impermeable sheet 21 having a length of 14 cm and a width of 40 cm so as to have an opening at the top. A water-absorbent sheet 10 wrapped with a liquid-impermeable sheet 21 is placed on a flat surface, and a liquid injection cylinder 45 (inner diameter 26 mm, outer diameter 30 mm, length 150 mm, weight 34 g) is placed on the liquid injection cylinder 45 (inner diameter 30 mm, outer diameter 30 mm, length 150 mm, weight 34 g). A weight having a diameter of 60 mm, a length of 62 mm, and a weight of 1030 g was attached, and a weight (FIG. 12) was placed in the center of the water-absorbent sheet 10 as shown in FIG. In this state, 0.9 wt% sodium chloride and 0.002 wt% edible blue No. 1 (Tokyo Chemical Industry) at 23 ° C. were put into the liquid injection cylinder 45 using a funnel 42 capable of charging the liquid at a flow velocity of 7 ml / sec. 80 g of an aqueous solution containing (Co., Ltd.) was added (FIG. 14). The time from the moment when the aqueous solution was charged until all the aqueous solution in the liquid charging cylinder 45 was absorbed by the water absorbing sheet 10 was measured. In this case, the liquid is added to the water-absorbent sheet 10 exposed from the liquid-impermeable sheet 21. Ten minutes after the liquid was added, 20 sheets of filter paper 43 (model No. 2, manufactured by ADVANTEC; circular one having a diameter of 110 mm) whose weight was measured in advance were placed on the center of the water-absorbent sheet 10 and a circular shape having a diameter of 100 mm. Weight 44 (1200 g) was further placed and held for 1 minute. After 1 minute, the weight 44 was removed, and the first reversion amount (g) was measured from the weight increment of the filter paper 43. 1 minute after removing the weight 44, the same operation (adding the liquid → measuring the water absorption time of the liquid → 10 minutes after adding the filter paper 43 and the weight 44 (1200 g), holding for 1 minute → 1 minute later Holding → removing the weight, measuring the amount of reversion) was repeated, and the amount of reversion was measured the second time (g) and the amount of reversion was measured the third time (g). Table 1 shows the total of the measured water absorption time and the amount of reversion from the first to the third.
　＜粒子状吸水剤の脱落率＞
　粒子状吸水剤の脱落率を以下のように算出した。４０ｃｍ×１０ｃｍの吸水性シートに対し、重量を測定後、第２の基材側の面と測面全体、および第１の基材側の面のうち外周から内側に向かって１ｃｍまでの面をビニールシートで覆ってテープで固定した。ビニールシートで覆った吸水性シートの表面に生理食塩水（０．９％塩化ナトリウム水溶液）３００ｍｌを均等に注いだ。生理食塩水の注水より１０分後、吸水性シートを覆っていたビニールシートを外し、吸水性シートをビニール袋（大倉工業株式会社製、ＯＫ袋Ｎｏ．１８、５３ｃｍ×３８ｃｍ）に入れた。電磁式ふるい振とう機　（Ｒｅｔｓｃｈ製、ＡＳ２００）の２本の支え棒それぞれにムッフ（ＡＳＳ　ＯＮＥ、ムッフ　ツメ付き　３６０°回転式）を取り付け、それぞれのムッフで１本のＳＵＳパイプ（直径１３ｍｍ、内径１０ｍｍ、長さ２９０ｍｍ）を地面と平行に固定し、ＳＵＳパイプに取り付けた大型クリップ（挟み口１５０ｍｍ）でビニール袋ごと吸水性シートを挟み、振動幅３ｍｍで１分間振動させた。電磁式ふるい振とう機の大型クリップからビニール袋ごと吸水性シートを取り外し、吸水性シートからビニール袋内に脱落した粒子状吸水剤の重量を測定した。以下の式より、粒子状吸水剤の脱落率を測定した。なお、下記式において、生理食塩水の重量は、３００ｇとする。
粒子状吸水剤の脱落率（％）
＝脱落した粒子状吸水剤（ｇ）／（吸水性シートの重量（ｇ）＋生理食塩水の重量（ｇ））×１００。 <Dropage rate of particulate water absorbent>
The dropout rate of the particulate water absorbent was calculated as follows. After measuring the weight of a 40 cm x 10 cm water-absorbent sheet, the surface on the second base material side and the entire measurement surface, and the surface on the first base material side from the outer circumference to the inside up to 1 cm are covered. It was covered with a vinyl sheet and fixed with tape. 300 ml of physiological saline (0.9% sodium chloride aqueous solution) was evenly poured on the surface of the water-absorbent sheet covered with a vinyl sheet. After 10 minutes from the injection of physiological saline, the vinyl sheet covering the water-absorbent sheet was removed, and the water-absorbent sheet was placed in a plastic bag (Okura Industrial Co., Ltd., OK bag No. 18, 53 cm × 38 cm). A muff (ASS ONE, 360 ° rotary type with muff claws) is attached to each of the two support rods of the electromagnetic sieve shaker (Resch, AS200), and one SUS pipe (diameter 13 mm, inner diameter 13 mm, inner diameter) is attached to each muff. A water-absorbent sheet (10 mm, length 290 mm) was fixed parallel to the ground, and a water-absorbent sheet was sandwiched together with a plastic bag with a large clip (sandwich opening 150 mm) attached to a SUS pipe, and vibrated for 1 minute with a vibration width of 3 mm. The water-absorbent sheet together with the plastic bag was removed from the large clip of the electromagnetic sieve shaker, and the weight of the particulate water-absorbent that fell into the plastic bag from the water-absorbent sheet was measured. The dropout rate of the particulate water absorbent was measured from the following formula. In the following formula, the weight of the physiological saline solution is 300 g.
Dropout rate of particulate water absorbent (%)
= Dropped particulate water absorbent (g) / (weight of water absorbing sheet (g) + weight of physiological saline (g)) x 100.
　表２に、実施例１１～１８の吸水性シートの構成および評価結果を示す。 Table 2 shows the configurations and evaluation results of the water-absorbent sheets of Examples 11 to 18.
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
　［実施例Ｂ］
　なお、以下の実施例においては、吸水層（粒子状吸水剤を含む領域）の上に第１の基材を積層した積層体が第２の基材の上に１層のみ積層される単層形態と、吸水層（粒子状吸水剤を含む領域）の上に第１の基材を積層した積層体が第２の基材の上に２層積層される二層形態と、が開示されている。単層形態および二層形態のどちらにおいても、「上方不織布」と称する場合は、液を直接的に吸収する吸液面を有する第１の基材を意味し、「下方不織布」と称する場合は、第２の基材を意味する。二層形態における液を直接的に吸収する吸液面を有する第１の基材以外の基材は、中間基材であり、ここでは「中間不織布」と称する。 [Example B]
In the following examples, a single layer in which only one layer of the first base material is laminated on the water absorbing layer (region containing the particulate water absorbing agent) is laminated on the second base material. Disclosed are a form and a two-layered form in which a laminate in which a first base material is laminated on a water absorbing layer (a region containing a particulate water absorbing agent) is laminated in two layers on a second base material. There is. In both the single-layer form and the two-layer form, the term "upper nonwoven fabric" means a first substrate having a liquid-absorbing surface that directly absorbs the liquid, and the term "lower nonwoven fabric" is used. , Means a second substrate. The base material other than the first base material having a liquid absorbing surface that directly absorbs the liquid in the two-layer form is an intermediate base material, and is referred to here as an "intermediate non-woven fabric".
　＜製造例＞
　［製造例１］
　以下の特許に記載の製造例、実施例、比較例を参考に、内部架橋剤量によって、ＣＲＣを適宜調整することで、ポリアクリル酸（塩）系樹脂の粒子状吸水剤（１）、（２）を得た。得られた粒子状吸水剤の物性を表３に示した。 <Manufacturing example>
[Manufacturing Example 1]
By appropriately adjusting the CRC according to the amount of the internal cross-linking agent with reference to the production examples, examples, and comparative examples described in the following patents, the particulate water absorbing agent (1) of the polyacrylic acid (salt) -based resin, ( 2) was obtained. The physical characteristics of the obtained particulate water absorbent are shown in Table 3.
　国際公開第２０１４／０３４８９７号
　国際公開第２０１７／１７０６０５号
　国際公開第２０１６／２０４３０２号
　国際公開第２０１４／０５４６５６号
　国際公開第２０１５／１５２２９９号
　国際公開第２０１８／０６２５３９号
　国際公開第２０１２／０４３８２１号。 International Publication No. 2014/034897 International Publication No. 2017/170605 International Publication No. 2016/204302 International Publication No. 2014/054656 International Publication No. 2015/152299 International Publication No. 2018/062539 International Publication No. 2012/043821.
　〔アクリル酸の製造例〕
　市販のアクリル酸（アクリル酸ダイマー２０００ｐｐｍ、酢酸５００ｐｐｍ、プロピオン酸５００ｐｐｍ、ｐ－メトキシフェノール２００ｐｐｍ）を、無堰多孔板５０段を有する高沸点不純物分離塔の塔底に供給して、還流比を１として蒸留し、マレイン酸やアクリル酸からなる二量体（アクリル酸ダイマー）などの除去後、さらに晶析を行なうことで、アクリル酸（アクリル酸ダイマー２０ｐｐｍ、酢酸５０ｐｐｍ、プロピオン酸５０ｐｐｍ、フルフラール１ｐｐｍ以下、プロトアネモニン１ｐｐｍ以下）を得て、さらに蒸留後にｐ－メトキシフェノールを５０ｐｐｍ添加した。 [Acrylic acid production example]
Commercially available acrylic acid (acrylic acid dimer 2000 ppm, acetic acid 500 ppm, propionic acid 500 ppm, p-methoxyphenol 200 ppm) is supplied to the bottom of a high boiling point impurity separation tower having 50 steps of a dam-free perforated plate, and the reflux ratio is set to 1. Acrylic acid (acrylic acid dimer 20 ppm, acetic acid 50 ppm, propionic acid 50 ppm, furfural 1 ppm or less) by distilling as, after removing dimer (acrylic acid dimer) composed of maleic acid and acrylic acid, and further performing crystallization. , Protoanemonin (1 ppm or less) was obtained, and 50 ppm of p-methoxyphenol was further added after distillation.
　〔アクリル酸ナトリウム水溶液の製法〕
　上記アクリル酸１３９０ｇを米国特許５２１０２９８号の実施例９に従い、４８％苛性ソーダを用いて２０～４０℃で中和して、濃度３７％で１００％中和のアクリル酸ナトリウム水溶液を得た。 [Manufacturing method of aqueous sodium acrylate solution]
According to Example 9 of US Pat. No. 5,210,298, 1390 g of the above acrylic acid was neutralized with 48% caustic soda at 20 to 40 ° C. to obtain a 100% neutralized sodium acrylic acid aqueous solution at a concentration of 37%.
　＜粒子状吸水剤（１）＞
　上記アクリル酸の製造例で得られたアクリル酸、該アクリル酸を用いて上記アクリル酸ナトリウム水溶液の製法で得られたアクリル酸ナトリウム水溶液、および脱イオン水を混合して得られた７５モル％の中和率を有するアクリル酸ナトリウムの水溶液５５００ｇ（単量体濃度３５．５質量％）に、ポリエチレングリコールジアクリレート（エチレンオキシドの平均付加モル数９）４．００ｇを溶解し反応液とした。次いで、シグマ型羽根を２本有する内容積１０Ｌのジャケット付きステンレス製双腕型ニーダーに蓋を付けて形成した反応器に、上記反応液を供給し、反応液を３０℃に保ちながら系を窒素ガス置換し、反応液中の溶存酸素を除去した。続いて、反応液を撹拌しながら、過硫酸ナトリウムの１０質量％水溶液２８．６６ｇ及びＬ－アスコルビン酸の１質量％水溶液３５．２８ｇを添加したところ、およそ１分後に重合が開始した。重合を開始して４０分後に１５０μｍ以下の吸水性樹脂微粉末を１８１．５ｇ添加したうえで、ニーダーのブレードを高速回転（１３０ｒｐｍ）で１０分間ゲル解砕してから含水ゲル状重合体を取り出した。得られた含水ゲル状重合体は約１～２ｍｍの粒子に細分化されていた。 <Particular water absorbent (1)>
75 mol% obtained by mixing the acrylic acid obtained in the above production example of acrylic acid, the aqueous sodium acrylate solution obtained by the above method for producing an aqueous sodium acrylate solution using the acrylic acid, and deionized water. 4.00 g of polyethylene glycol diacrylate (average number of moles of ethylene oxide added 9) was dissolved in 5500 g (monomer concentration 35.5% by mass) of an aqueous solution of sodium acrylate having a neutralization rate to prepare a reaction solution. Next, the above reaction solution was supplied to a reactor formed by attaching a lid to a stainless steel double-armed kneader with an internal volume of 10 L having two sigma type blades, and the system was nitrogenized while keeping the reaction solution at 30 ° C. Gas replacement was performed to remove dissolved oxygen in the reaction solution. Subsequently, 28.66 g of a 10 mass% aqueous solution of sodium persulfate and 35.28 g of a 1 mass% aqueous solution of L-ascorbic acid were added while stirring the reaction solution, and the polymerization started after about 1 minute. 40 minutes after the start of polymerization, 181.5 g of water-absorbent resin fine powder of 150 μm or less was added, and the kneader blade was gel-crushed at high speed (130 rpm) for 10 minutes, and then the hydrogel polymer was taken out. It was. The obtained hydrogel polymer was subdivided into particles having a size of about 1 to 2 mm.
　この細分化された含水ゲル状重合体を５０メッシュ（目の大きさ３００μｍ）の金網上に広げ、１７５℃で６５分間熱風乾燥した。次いで、乾燥物をロールミルを用いて粉砕し、さらに目開き６００μｍの金網で分級、調合することにより、平均粒子径３５０μｍの不定形破砕状の吸水性樹脂（１－１）を得た。得られた吸水性樹脂（１－１）１００質量部に、エチレングリコールジグリシジルエーテル０．０３質量部、プロピレングリコール１．０質量部、水３．０質量部からなる表面架橋剤水溶液４．０３質量部を噴霧混合した。上記の混合物を、パドル型混合加熱処理機を用いて、熱媒温度１００℃で４０分間加熱処理して表面架橋された吸水性樹脂（１－２）を得た。得られた表面架橋された吸水性樹脂（１－２）１００質量部に、水３．０質量部を噴霧混合して、密閉容器内で６０℃で１時間硬化させた後、目開き７１０μｍのふるいを通過させて吸水性樹脂（１－３）を得た。吸水性樹脂（１－３）にＡｅｒｏｓｉｌ９０Ｇ（親水性アモルファスシリカ、日本アエロジル社製）を０．３質量部添加して混合することにより得た吸水性樹脂を粒子状吸水剤（１）とした。 This subdivided hydrogel polymer was spread on a wire mesh of 50 mesh (mesh size 300 μm) and dried with hot air at 175 ° C. for 65 minutes. Next, the dried product was pulverized using a roll mill, further classified and blended with a wire mesh having a mesh size of 600 μm to obtain an amorphous crushed water-absorbent resin (1-1) having an average particle diameter of 350 μm. A surface cross-linking agent aqueous solution containing 0.03 parts by mass of ethylene glycol diglycidyl ether, 1.0 part by mass of propylene glycol, and 3.0 parts by mass of water in 100 parts by mass of the obtained water-absorbent resin (1-1) 4.03. The parts by mass were spray-mixed. The above mixture was heat-treated at a heat medium temperature of 100 ° C. for 40 minutes using a paddle-type mixing heat treatment machine to obtain a surface-crosslinked water-absorbent resin (1-2). 3.0 parts by mass of water was spray-mixed with 100 parts by mass of the obtained surface-crosslinked water-absorbent resin (1-2) and cured at 60 ° C. for 1 hour in a closed container, and then the opening was 710 μm. A water-absorbent resin (1-3) was obtained by passing through a sieve. The water-absorbent resin obtained by adding 0.3 parts by mass of Aerosil 90G (hydrophilic amorphous silica, manufactured by Nippon Aerosil Co., Ltd.) to the water-absorbent resin (1-3) and mixing them was used as a particulate water-absorbent resin (1).
　〔粒子状吸水剤の物性の測定方法〕
　＜重量平均粒子径＞
　本発明の一実施形態に係る粒子状吸水剤（もしくは、粒子状の吸水性樹脂、吸水性樹脂粒子）の粒子径は、ＥＲＴ４２０．２－０２に規定される「ＰＳＤ」の測定方法に従って得られた重量平均粒子径である。各粒子状吸水剤の重量平均粒子径は表３に示す。 [Measuring method of physical properties of particulate water absorbent]
<Weight average particle size>
The particle size of the particulate water-absorbing agent (or particulate water-absorbent resin, water-absorbent resin particles) according to the embodiment of the present invention is obtained according to the measurement method of "PSD" specified in ERT420.2-02. Weight average particle size. The weight average particle size of each particulate water absorbent is shown in Table 3.
　＜ＣＲＣ（無加圧下吸水倍率）（ＥＲＴ４４１．２－０２）＞
　粒子状吸水剤０．２ｇ（吸水前重量）を不織布製の袋に入れた後、大過剰の０．９質量％塩化ナトリウム水溶液中に３０分間浸漬して自由膨潤させ、その後、遠心分離機（２５０Ｇ）で水切りした後の粒子状吸水剤の吸水後重量を測定する。吸水倍率（単位；ｇ／ｇ）は、「（粒子状吸水剤の吸水後重量－粒子状吸水剤の吸水前重量）／（粒子状吸水剤の吸水前重量）×１００」により求められる。各粒子状吸水剤のＣＲＣは表４、表６に示す。 <CRC (Unpressurized Water Absorption Magnification) (ERT441.2-02)>
0.2 g of the particulate water absorbent (weight before water absorption) is placed in a non-woven bag, and then immersed in a large excess of 0.9 mass% sodium chloride aqueous solution for 30 minutes for free swelling, and then a centrifuge (centrifugal separator). The weight of the particulate water-absorbing agent after draining with 250G) is measured. The water absorption ratio (unit: g / g) is determined by "(weight of the particulate water absorbent after water absorption-weight of the particulate water absorbent before water absorption) / (weight of the particulate water absorbent before water absorption) x 100". The CRC of each particulate water absorbent is shown in Tables 4 and 6.
　＜表面張力＞
　本発明において、表面張力は、粒子状吸水剤を０．９０質量％塩化ナトリウム水溶液中に分散させた際の、水溶液の表面張力を意味する。 <Surface tension>
In the present invention, the surface tension means the surface tension of the aqueous solution when the particulate water absorbent is dispersed in the 0.90 mass% sodium chloride aqueous solution.
　十分に洗浄された１００ｍｌのビーカーに２０℃に調整された生理食塩水５０ｍｌを入れ、まず、生理食塩水の表面張力を、表面張力計（ＫＲＵＳＳ社製のＫ１１自動表面張力計）を用いて測定する。なお、本発明では、白金プレートを用いるプレート法を採用し、プレートは各測定前に十分脱イオン水にて洗浄し、かつ、ガスバーナーで加熱洗浄して使用する。 50 ml of physiological saline adjusted to 20 ° C. is placed in a thoroughly washed 100 ml beaker, and the surface tension of the physiological saline is first measured using a surface tension meter (K11 automatic surface tension meter manufactured by KRUSS). To do. In the present invention, a plate method using a platinum plate is adopted, and the plate is sufficiently washed with deionized water before each measurement and heated and washed with a gas burner before use.
　次に、２０℃に調整した表面張力測定後の生理食塩水を含んだビーカーに、十分に洗浄された２５ｍｍ長のフッ素樹脂製回転子、および粒子状吸水剤０．５ｇを投入し、５００ｒｐｍの条件で４分間攪拌する。４分後、攪拌を止め、含水した粒子状吸水剤が沈降した後に、上澄み液の表面張力を再度同様の操作を行い測定する。ここで、粒子状吸水剤の表面張力（単位：ｍＮ／ｍ）は、生理食塩水に粒子状吸水剤を分散させた際の上澄み液の表面張力により求められる。各粒子状吸水剤の表面張力は表４、表６に示す。 Next, a fully washed 25 mm long fluororesin rotor and 0.5 g of a particulate water absorbent were placed in a beaker containing a physiological saline solution adjusted to 20 ° C. after measuring the surface tension, at 500 rpm. Stir for 4 minutes under the conditions. After 4 minutes, the stirring is stopped, and after the water-containing particulate water absorbent has settled, the surface tension of the supernatant is measured again by performing the same operation. Here, the surface tension of the particulate water-absorbing agent (unit: mN / m) is determined by the surface tension of the supernatant liquid when the particulate water-absorbing agent is dispersed in physiological saline. The surface tension of each particulate water absorbent is shown in Tables 4 and 6.
　〔実施例〕
　＜型紙の準備＞
　粒子状吸水剤を不織布上に筋状に散布するため、型紙１～６を準備した。型紙１～６は、縦１４ｃｍ、横４４ｃｍの紙に、長手方向に沿って直線状に、粒子状吸水剤の存在領域と、粒子状吸水剤の非存在領域とが形成されるように、粒子状吸水剤の存在領域となる部分に穴を開けた。なお、型紙１～６において、その外周２ｃｍは枠とし、紙を切断しないものとする（すなわち、型紙は、枠を除く領域において、短手方向に端から順に、粒子状吸水剤の存在領域の部分を繰りぬいて穴とする）。型紙１～６により形成される形状（Ｓ－１）～（Ｓ－６）を図１５（ａ）～図１５（ｃ）、図１６（ａ）～図１６（ｃ）に基づいて説明する。図１５（ａ）～図１５（ｃ）、図１６（ａ）～図１６（ｃ）は、単層形態の吸水性シートを短手方向に沿って切断した断面模式図である。なお、形状（Ｓ－１）～（Ｓ－６）は、吸水性シートの短手方向中央部に対して左右対称となるように、粒子状吸水剤１４が含まれる領域と、間隙１５とが形成されている。よって、下記で示す「粒子状吸水剤１４」と「間隙１５」との領域比は、短手方向に沿って左右どちらからでもよい。 〔Example〕
<Preparation of paper pattern>
Patterns 1 to 6 were prepared in order to spray the particulate water absorbing agent on the non-woven fabric in a streak pattern. The patterns 1 to 6 are particles such that a region in which the particulate water-absorbing agent is present and a region in which the particulate water-absorbing agent is not present are formed linearly along the longitudinal direction on a paper having a length of 14 cm and a width of 44 cm. A hole was made in the area where the water absorbent was present. In the paper patterns 1 to 6, the outer circumference 2 cm thereof shall be a frame, and the paper shall not be cut (that is, the paper pattern shall be a region in which the particulate water absorbing agent is present in the region excluding the frame, in order from the end in the lateral direction. Cut out the part to make a hole). The shapes (S-1) to (S-6) formed by the patterns 1 to 6 will be described with reference to FIGS. 15 (a) to 15 (c) and FIGS. 16 (a) to 16 (c). 15 (a) to 15 (c) and 16 (a) to 16 (c) are schematic cross-sectional views of a single-layer water-absorbent sheet cut along the lateral direction. The shapes (S-1) to (S-6) have a region containing the particulate water absorbing agent 14 and a gap 15 so as to be symmetrical with respect to the central portion of the water absorbing sheet in the lateral direction. It is formed. Therefore, the region ratio between the "particulate water absorbing agent 14" and the "gap 15" shown below may be from either the left or right along the lateral direction.
　図１５（ａ）は、型紙１により形成される（Ｓ－１）形状である。（Ｓ－１）形状は、第１の基材１１と第２の基材１３との間に、「粒子状吸水剤１４：１５ｍｍ、間隙１５：２５ｍｍ、粒子状吸水剤１４：２０ｍｍ、間隙１５：２５ｍｍ、粒子状吸水剤１４：１５ｍｍ」が短手方向に沿って順に形成されている。 FIG. 15 (a) is a (S-1) shape formed by the paper pattern 1. The shape of (S-1) is as follows: "Particular water absorbing agent 14:15 mm, gap 15:25 mm, particulate water absorbing agent 14:20 mm, gap 15" between the first base material 11 and the second base material 13. : 25 mm, particulate water absorbing agent 14:15 mm ”are formed in order along the lateral direction.
　図１５（ｂ）は、型紙２により形成される（Ｓ－２）形状である。（Ｓ－２）形状は、第１の基材１１と第２の基材１３との間に、「粒子状吸水剤１４：２０ｍｍ、間隙１５：２０ｍｍ、粒子状吸水剤１４：２０ｍｍ、間隙１５：２０ｍｍ、粒子状吸水剤１４：２０ｍｍ」が短手方向に沿って順に形成されている。 FIG. 15 (b) is a (S-2) shape formed by the paper pattern 2. The shape of (S-2) is as follows: "Particular water absorbing agent 14:20 mm, gap 15:20 mm, particulate water absorbing agent 14:20 mm, gap 15" between the first base material 11 and the second base material 13. : 20 mm, particulate water absorbing agent 14:20 mm ”are formed in order along the lateral direction.
　図１５（ｃ）は、型紙３により形成される（Ｓ－３）形状である。（Ｓ－３）形状は、第１の基材１１と第２の基材１３との間に、「粒子状吸水剤１４：１０ｍｍ、間隙１５：３５ｍｍ、粒子状吸水剤１４：１０ｍｍ、間隙１５：３５ｍｍ、粒子状吸水剤１４：１０ｍｍ」が短手方向に沿って順に形成されている。 FIG. 15 (c) is a (S-3) shape formed by the paper pattern 3. The shape of (S-3) is as follows: "Particular water absorbing agent 14:10 mm, gap 15:35 mm, particulate water absorbing agent 14:10 mm, gap 15" between the first base material 11 and the second base material 13. : 35 mm, particulate water absorbent 14:10 mm ”are formed in order along the lateral direction.
　図１６（ａ）は、型紙４により形成される（Ｓ－４）形状である。（Ｓ－４）形状は、第１の基材１１と第２の基材１３との間に、「粒子状吸水剤１４：２５ｍｍ、間隙１５：１０ｍｍ、粒子状吸水剤１４：３０ｍｍ、間隙１５：１０ｍｍ、粒子状吸水剤１４：２５ｍｍ」が短手方向に沿って順に形成されている。 FIG. 16A is a (S-4) shape formed by the paper pattern 4. The shape of (S-4) is as follows: "Particular water absorbing agent 14:25 mm, gap 15:10 mm, particulate water absorbing agent 14:30 mm, gap 15" between the first base material 11 and the second base material 13. : 10 mm, particulate water absorbing agent 14:25 mm ”are formed in order along the lateral direction.
　図１６（ｂ）は、型紙５により形成される（Ｓ－５）形状である。（Ｓ－５）形状は、第１の基材１１と第２の基材１３との間に、「粒子状吸水剤１４：１７．５ｍｍ、間隙１５：１０ｍｍ、粒子状吸水剤１４：１７．５ｍｍ、間隙１５：１０ｍｍ、粒子状吸水剤１４：１７．５ｍｍ、間隙１５：１０ｍｍ、粒子状吸水剤１４：１７．５ｍｍ」が短手方向に沿って順に形成されている。 FIG. 16B is a (S-5) shape formed by the paper pattern 5. The shape of (S-5) is such that between the first base material 11 and the second base material 13, "particulate water absorbing agent 14: 17.5 mm, gap 15:10 mm, particulate water absorbing agent 14:17. "5 mm, gap 15:10 mm, particulate water absorbing agent 14: 17.5 mm, gap 15:10 mm, particulate water absorbing agent 14: 17.5 mm" are formed in this order along the lateral direction.
　図１６（ｃ）は、型紙６により形成される（Ｓ－６）形状である。（Ｓ－６）形状は、第１の基材１１と第２の基材１３との間に、「粒子状吸水剤１４：１０ｍｍ、間隙１５：５ｍｍ、粒子状吸水剤１４：１０ｍｍ、間隙１５：５ｍｍ、粒子状吸水剤１４：１０ｍｍ、間隙１５：５ｍｍ、粒子状吸水剤１４：１０ｍｍ、間隙１５：５ｍｍ、粒子状吸水剤１４：１０ｍｍ、間隙１５：５ｍｍ、粒子状吸水剤１４：１０ｍｍ、間隙１５：５ｍｍ、粒子状吸水剤１４：１０ｍｍ」が短手方向に沿って順に形成されている。 FIG. 16 (c) is a (S-6) shape formed by the paper pattern 6. The shape of (S-6) is as follows: "Particular water absorbing agent 14:10 mm, gap 15: 5 mm, particulate water absorbing agent 14:10 mm, gap 15" between the first base material 11 and the second base material 13. : 5 mm, Particle Water Absorbent 14:10 mm, Gap 15: 5 mm, Particle Water Absorbent 14:10 mm, Gap 15: 5 mm, Particle Water Absorbent 14:10 mm, Gap 15: 5 mm, Particle Water Absorbent 14:10 mm, A gap of 15: 5 mm and a particulate water absorbing agent of 14:10 mm ”are formed in order along the lateral direction.
　［例１］
　縦１０ｃｍ、横４０ｃｍに切断した不織布Ａ（エアスルー法で作製されたもの。オレフィンを主成分とし、厚み１．４ｍｍ。中間不織布に相当する）に、型紙１（図１５（ａ）参照）を載せた。型紙１には３つの長方形の穴があり、その穴から型紙１の下の不織布Ａが最大限に見えるように位置を調整した。型紙１の全ての穴の総合面積に対するそれぞれの穴の面積比を計算し、粒子状吸水剤（１）４．５ｇ（散布量：１１２．５ｇ／ｍ２）をそれぞれの穴の面積比で分けて測りとり、それぞれの穴から見える不織布Ａに対して均一に散布した。型紙の上に粒子状吸水剤（１）の一部が散布された場合、粒子状吸水剤（１）を散布している不織布Ａに向かって型紙１を傾けて、粒子状吸水剤を型紙１の穴に落とした。その後、型紙１を不織布Ａから取り外した。 [Example 1]
Pattern 1 (see FIG. 15 (a)) is placed on non-woven fabric A (made by the air-through method, which is mainly composed of olefin and has a thickness of 1.4 mm, which corresponds to an intermediate non-woven fabric) cut into a length of 10 cm and a width of 40 cm. It was. The pattern 1 has three rectangular holes, and the positions are adjusted so that the non-woven fabric A under the pattern 1 can be seen as much as possible from the holes. Calculate the area ratio of each hole to the total area of all the holes of the pattern 1, and divide 4.5 g (spray amount: 112.5 g / m 2 ) of the particulate water absorbent (1) by the area ratio of each hole. It was measured and evenly sprayed on the non-woven fabric A visible from each hole. When a part of the particulate water absorbing agent (1) is sprayed on the paper pattern, the paper pattern 1 is tilted toward the non-woven fabric A on which the particulate water absorbing agent (1) is sprayed, and the particulate water absorbing agent is applied to the paper pattern 1. I dropped it in the hole. Then, the paper pattern 1 was removed from the non-woven fabric A.
　前記の不織布Ａとは別に、縦１０ｃｍ、横４０ｃｍに切断した不織布Ａ（上記不織布Ａと同じものである（厚み１．４ｍｍ）。以下、不織布Ａ２と称する。第１の基材（上方不織布）に相当する）に、スチレンブタジエンゴムを含む接着剤（スプレーのり７７、スリーエムジャパン株式会社製）０．７～０．９ｇを均一に散布（散布量：１７．５～２１．５ｇ／ｍ）した後、不織布Ａの粒子状吸水剤（１）を散布した面と不織布Ａ２の接着剤を散布した面が対合するように（接触するように）重ね、加圧圧着した。 Separately from the non-woven fabric A, the non-woven fabric A cut into a length of 10 cm and a width of 40 cm (the same as the non-woven fabric A (thickness 1.4 mm). Hereinafter referred to as non-woven fabric A2. First base material (upper non-woven fabric)) 0.7 to 0.9 g of an adhesive containing styrene butadiene rubber (spray glue 77, manufactured by 3M Japan Co., Ltd.) was uniformly sprayed (spray amount: 17.5 to 21.5 g / m). After that, the surface on which the particulate water absorbing agent (1) of the nonwoven fabric A was sprayed and the surface on which the adhesive of the nonwoven fabric A2 was sprayed were overlapped (contacted) and pressure-bonded.
　粒子状吸水剤（１）と面していない側の不織布Ａの表面に、型紙１（図１５（ａ）参照）を載せた。型紙１の３つの長方形の穴から、型紙１の下の不織布Ａが最大限に見えるように位置を調整した。型紙１の全ての穴の総合面積に対するそれぞれの穴の面積比を計算し、粒子状吸水剤（１）４．５ｇをそれぞれの穴の面積比で分けて測りとり、それぞれの穴から見える不織布Ａに対して均一に散布した。型紙の上に粒子状吸水剤（１）の一部が散布された場合、粒子状吸水剤（１）を散布している不織布Ａに向かって型紙１を傾けて、粒子状吸水剤を型紙１の穴に落とした。その後、型紙１を不織布Ａから取り外した。 Pattern 1 (see FIG. 15A) was placed on the surface of the non-woven fabric A on the side not facing the particulate water absorbing agent (1). The position was adjusted so that the non-woven fabric A under the pattern 1 could be seen to the maximum through the three rectangular holes of the pattern 1. Calculate the area ratio of each hole to the total area of all the holes of the paper pattern 1, measure 4.5 g of the particulate water absorbent (1) separately by the area ratio of each hole, and measure the non-woven fabric A that can be seen from each hole. Was sprayed evenly. When a part of the particulate water absorbing agent (1) is sprayed on the paper pattern, the paper pattern 1 is tilted toward the non-woven fabric A on which the particulate water absorbing agent (1) is sprayed, and the particulate water absorbing agent is applied to the paper pattern 1. I dropped it in the hole. Then, the paper pattern 1 was removed from the non-woven fabric A.
　縦１０ｃｍ、横４０ｃｍの不織布Ｅ（エアレイド法で作成されたもの。パルプ繊維を主成分とする。厚み０．４ｍｍ。目付量：４７ｇ／ｍ２。第２の基材（下方不織布）に相当する。）に、前記の接着剤０．７～０．９ｇを均一に散布した後、不織布Ａの粒子状吸水剤（１）を散布した面と不織布Ｅの接着剤を散布した面が対合するように（接触するように）重ね、加圧圧着して中間体シートＸを得た。 Non-woven fabric E with a length of 10 cm and a width of 40 cm (made by the airlaid method. The main component is pulp fiber. Thickness 0.4 mm. Metsuke amount: 47 g / m 2. Corresponds to the second base material (lower non-woven fabric). ), After uniformly spraying 0.7 to 0.9 g of the adhesive, the surface on which the particulate water absorbent (1) of the non-woven fabric A is sprayed and the surface on which the adhesive of the non-woven fabric E is sprayed face each other. The intermediate sheet X was obtained by stacking them in such a manner (contacting each other) and pressure-bonding them.
　最後に、中間体シートＸを縦２４ｃｍ、横４０ｃｍに切断した不織布Ｆ（スパンボンド法で作製したもの。オレフィンを主成分とし、厚み０．１ｍｍ。目付量：１３ｇ／ｍ２。嵩密度：０．１５ｇ／ｃｍ３。ラッピングシートに相当）で包み、吸水性シート（１）を得た。 Finally, the non-woven fabric F (made by the spunbond method) obtained by cutting the intermediate sheet X into a length of 24 cm and a width of 40 cm. The main component is olefin, the thickness is 0.1 mm, the basis weight: 13 g / m 2, and the bulk density: 0. .15 g / cm 3 (corresponding to a wrapping sheet) was wrapped to obtain a water-absorbent sheet (1).
　［実施例２］
　縦２４ｃｍ、横４０ｃｍに切断した不織布Ｆ（ラッピングシートに相当）を敷いておき、その上に、縦１０ｃｍ、横４０ｃｍに切断した不織布Ａ（第１の基材に相当）を載せ、不織布Ａの表面に、型紙１（図１５（ａ）参照）を載せた。型紙１の３つの長方形の穴から、型紙１の下の不織布Ａが最大限に見えるように位置を調整した。型紙１の全ての穴の総合面積に対するそれぞれの穴の面積比を計算し、粒子状吸水剤（１）９．０ｇ（散布量：２２５ｇ／ｍ２）をそれぞれの穴の面積比で分けて測りとり、それぞれの穴から見える不織布Ａに対して均一に散布した。型紙の上に粒子状吸水剤（１）の一部が散布された場合、粒子状吸水剤（１）を散布している不織布Ａに向かって型紙１を傾けて、粒子状吸水剤を型紙１の穴に落とした。その後、型紙１を不織布Ａから取り外した。 [Example 2]
Non-woven fabric F (corresponding to a wrapping sheet) cut into a length of 24 cm and a width of 40 cm is laid, and non-woven fabric A (corresponding to a first base material) cut into a length of 10 cm and a width of 40 cm is placed on the non-woven fabric F. A pattern 1 (see FIG. 15 (a)) was placed on the surface. The position was adjusted so that the non-woven fabric A under the pattern 1 could be seen to the maximum through the three rectangular holes of the pattern 1. Calculate the area ratio of each hole to the total area of all the holes of the paper pattern 1, and measure 9.0 g (spray amount: 225 g / m 2 ) of the particulate water absorbent (1) by dividing it by the area ratio of each hole. It was evenly sprayed on the non-woven fabric A visible from each hole. When a part of the particulate water absorbing agent (1) is sprayed on the paper pattern, the paper pattern 1 is tilted toward the non-woven fabric A on which the particulate water absorbing agent (1) is sprayed, and the particulate water absorbing agent is applied to the paper pattern 1. I dropped it in the hole. Then, the paper pattern 1 was removed from the non-woven fabric A.
　縦１０ｃｍ、横４０ｃｍの不織布Ｅ（第２の基材に相当）に、スチレンブタジエンゴムを含む接着剤（スプレーのり７７、スリーエムジャパン株式会社製）を０．７～０．９ｇ均一に散布（散布量：１７．５～２１．５ｇ／ｍ）した後、不織布Ａの粒子状吸水剤（１）を散布した面と不織布Ｅの接着剤を散布した面が対合するように（接触するように）重ね、加圧圧着して中間体シートＹを得た。 0.7 to 0.9 g of an adhesive containing styrene-butadiene rubber (spray glue 77, manufactured by 3M Japan Co., Ltd.) is uniformly sprayed (sprayed) on a non-woven fabric E (corresponding to the second base material) having a length of 10 cm and a width of 40 cm. Amount: 17.5 to 21.5 g / m), so that the surface of the non-woven fabric A sprayed with the particulate water absorbent (1) and the surface sprayed with the adhesive of the non-woven fabric E face each other (contact each other). ) Stacking and pressure crimping to obtain an intermediate sheet Y.
　最後に、中間体シートＹを前記の不織布Ｆで包み、加圧圧着することで、吸水性シート（２）を得た。 Finally, the intermediate sheet Y was wrapped with the above-mentioned non-woven fabric F and pressure-bonded to obtain a water-absorbent sheet (2).
　［実施例３］
　エアスルー不織布Ａの代わりに、厚み０．７ｍｍのエアスルー不織布Ｇを用いた以外は、実施例２と同様にして、吸水性シート（３）を得た。 [Example 3]
A water-absorbent sheet (3) was obtained in the same manner as in Example 2 except that the air-through nonwoven fabric G having a thickness of 0.7 mm was used instead of the air-through nonwoven fabric A.
　［実施例４］
　型紙１の代わりに、型紙２（図１５（ｂ）参照）を用いた以外は、実施例２と同様にして、吸水性シート（４）を得た。 [Example 4]
A water-absorbent sheet (4) was obtained in the same manner as in Example 2 except that the paper pattern 2 (see FIG. 15B) was used instead of the paper pattern 1.
　［実施例５］
　型紙１の代わりに、型紙３（図１５（ｃ）参照）を用いた以外は、実施例２と同様にして、吸水性シート（５）を得た。 [Example 5]
A water-absorbent sheet (5) was obtained in the same manner as in Example 2 except that the pattern 3 (see FIG. 15 (c)) was used instead of the pattern 1.
　［実施例６］
　型紙１の代わりに、型紙４（図１６（ａ）参照）を用いた以外は、実施例２と同様にして、吸水性シート（６）を得た。 [Example 6]
A water-absorbent sheet (6) was obtained in the same manner as in Example 2 except that the paper pattern 4 (see FIG. 16A) was used instead of the paper pattern 1.
　［実施例７］
　型紙１の代わりに、型紙５（図１６（ｂ）参照）を用いた以外は、実施例２と同様にして、吸水性シート（７）を得た。 [Example 7]
A water-absorbent sheet (7) was obtained in the same manner as in Example 2 except that the pattern 5 (see FIG. 16B) was used instead of the pattern 1.
　［実施例８］
型紙１の代わりに、型紙６（図１６（ｃ）参照）を用いた以外は、実施例２と同様にして、吸水性シート（８）を得た。 [Example 8]
A water-absorbent sheet (8) was obtained in the same manner as in Example 2 except that the paper pattern 6 (see FIG. 16C) was used instead of the paper pattern 1.
　［実施例９］
　不織布Ａの代わりに、不織布Ｂ（エアスルー法で作製されたもの。オレフィンを主成分とし、厚み２．０ｍｍ。）を用いた以外は、実施例２と同様にして、吸水性シート（９）を得た。 [Example 9]
The water-absorbent sheet (9) was prepared in the same manner as in Example 2 except that the non-woven fabric B (produced by the air-through method. The main component was olefin and the thickness was 2.0 mm) was used instead of the non-woven fabric A. Obtained.
　［実施例１０］
　不織布Ａの代わりに、不織布Ｃ（エアスルー法で作製されたもの。オレフィンを主成分とし、厚み１．５ｍｍ。）を用いた以外は、実施例２と同様にして、吸水性シート（１０）を得た。 [Example 10]
The water-absorbent sheet (10) was prepared in the same manner as in Example 2 except that the non-woven fabric C (manufactured by the air-through method. The main component was olefin and the thickness was 1.5 mm) was used instead of the non-woven fabric A. Obtained.
　［比較例１］
縦１０ｃｍ、横４０ｃｍに切断した不織布Ａに、粒子状吸水剤（１）４．５ｇを均一に散布した。 [Comparative Example 1]
4.5 g of the particulate water absorbing agent (1) was uniformly sprayed on the non-woven fabric A cut into a length of 10 cm and a width of 40 cm.
　縦１０ｃｍ、横４０ｃｍの不織布Ｅ（第１の基材に相当する。）に、スチレンブタジエンゴムを含む接着剤（スプレーのり７７、スリーエムジャパン株式会社製）０．７～０．９ｇを均一に散布（散布量：１７．５～２１．５ｇ／ｍ）した後、不織布Ａの粒子状吸水剤（１）を散布した面と不織布Ｅの接着剤を散布した面が対合するように（接触するように）重ね、加圧圧着した。 0.7 to 0.9 g of an adhesive containing styrene-butadiene rubber (Spray Glue 77, manufactured by 3M Japan Ltd.) is uniformly sprayed on a non-woven fabric E (corresponding to the first base material) having a length of 10 cm and a width of 40 cm. (Spray amount: 17.5 to 21.5 g / m), the surface on which the particulate water absorbing agent (1) of the non-woven fabric A is sprayed and the surface on which the adhesive of the non-woven fabric E is sprayed face each other (contact). (Like) and pressure-bonded.
　粒子状吸水剤（１）と面していない側の不織布Ａの表面に、粒子状吸水剤（１）４．５ｇを均一に散布した。 4.5 g of the particulate water absorbent (1) was uniformly sprayed on the surface of the non-woven fabric A on the side not facing the particulate water absorbent (1).
　前記の不織布Ｅとは別に、縦１０ｃｍ、横４０ｃｍの不織布Ｅ（以下、不織布Ｅ２と称する。第２の基材に相当する。）に、前記の接着剤０．７～０．９ｇを均一に散布した後、不織布Ａの粒子状吸水剤（１）を散布した面と不織布Ｅ２の接着剤を散布した面が対合するように（接触するように）重ね、加圧圧着して中間体シートＺを得た。最後に、中間体シートＺを不織布Ｆで包み、加圧圧着することで、吸水性シート（１１）を得た。 Apart from the non-woven fabric E, 0.7 to 0.9 g of the adhesive is uniformly applied to the non-woven fabric E having a length of 10 cm and a width of 40 cm (hereinafter referred to as non-woven fabric E2, which corresponds to a second base material). After spraying, the surface on which the particulate water absorbing agent (1) of the non-woven fabric A is sprayed and the surface on which the adhesive of the non-woven fabric E2 is sprayed are overlapped so as to face each other (contact), and pressure-bonded to form an intermediate sheet. I got Z. Finally, the intermediate sheet Z was wrapped with the non-woven fabric F and pressure-bonded to obtain a water-absorbent sheet (11).
　［比較例２］
　型紙１を用いずに、粒子状吸水剤（１）を不織布Ａに均一に全面に散布した点を除いては、実施例１と同様にして、吸水性シート（１２）を得た。 [Comparative Example 2]
A water-absorbent sheet (12) was obtained in the same manner as in Example 1 except that the particulate water-absorbent agent (1) was uniformly sprayed on the entire surface of the non-woven fabric A without using the paper pattern 1.
　［比較例３］
　不織布Ａ２の代わりに不織布Ｅを用いた点を除いては、実施例１と同様にして、吸水性シート（１３）を得た。中間不織布については、不織布Ａを用いている。 [Comparative Example 3]
A water-absorbent sheet (13) was obtained in the same manner as in Example 1 except that the non-woven fabric E was used instead of the non-woven fabric A2. As the intermediate non-woven fabric, the non-woven fabric A is used.
　［比較例４］
　不織布Ａの代わりに不織布Ｅを用いた点を除いては、実施例２と同様にして、吸水性シート（１４）を得た。 [Comparative Example 4]
A water-absorbent sheet (14) was obtained in the same manner as in Example 2 except that the non-woven fabric E was used instead of the non-woven fabric A.
　なお、本実施例で使用した不織布Ａ～Ｃ、Ｇは、いずれも透水性シートであった。 The non-woven fabrics A to C and G used in this example were all water permeable sheets.
　〔不織布の物性の測定方法〕
　例１、実施例２～１０および比較例１～４で用いた不織布Ａ～Ｃ、ＥおよびＧの伸び率、厚み、嵩密度、液拡散面積、不織布に対する粒子状吸水剤の透過率は、以下の方法に従って測定した。 [Measuring method of physical properties of non-woven fabric]
The elongation rates, thickness, bulk density, liquid diffusion area, and transmittance of the particulate water absorbent to the non-woven fabrics used in Examples 1, Examples 2 to 10 and Comparative Examples 1 to 4 are as follows. It was measured according to the method of.
　［伸び率の測定方法］
　伸び率測定用の不織布を長辺が１００ｍｍ、短辺が３０ｍｍの長方形に切り取った。このとき、長辺は不織布ロールの幅方向であり、短辺は不織布ロールの巻き取り長さ方向とする。なお、本実施例で吸水性シートに用いられる縦（短辺）１００ｍｍ、横（長辺）４００ｍｍのサイズの不織布は、縦（短辺）を不織布ロールの幅方向とし、横（長辺）を不織布ロールの巻き取り長さ方向としている。図１７（ａ）のように、切り取った伸び率測定用の不織布の両端から５ｍｍの位置に対し、それぞれ短辺と並行になるように目安線を引いた。目安線に重なるように、それぞれダブルクリップで挟んだ（図１７（ｂ））。ダブルクリップは、爪の長さが３０ｍｍ以上のものを用いた。一方のダブルクリップには錘を取りつけ、錘を取り付けたダブルクリップと錘を足した重さは１１０ｇとした。室温雰囲気下で、錘のついていないダブルクリップを持ち、もう一方のダブルクリップについた錘が空中に浮くように持ち上げ、不織布がダブルクリップと錘の重さで伸びた状態を２０秒維持した。その直後、空中に浮かせたまま不織布の長辺方向の長さを測定した（図１７（ｃ））。空中に浮かした後の長辺の長さと空中に浮かせる前の長辺の長さ１００ｍｍより、空中に浮かした後の長さがどの程度伸びているか、次の式を使用して比率を求め、伸び率とした。 [Measurement method of elongation rate]
The non-woven fabric for measuring the elongation was cut into a rectangle having a long side of 100 mm and a short side of 30 mm. At this time, the long side is in the width direction of the non-woven fabric roll, and the short side is in the winding length direction of the non-woven fabric roll. In the non-woven fabric having a length (short side) of 100 mm and a width (long side) of 400 mm used for the water-absorbent sheet in this embodiment, the length (short side) is the width direction of the non-woven fabric roll and the width (long side) is the width direction. The winding length direction of the non-woven fabric roll is used. As shown in FIG. 17A, reference lines were drawn at positions 5 mm from both ends of the cut non-woven fabric for measuring the elongation rate so as to be parallel to the short sides. Each was sandwiched between double clips so as to overlap the reference line (FIG. 17 (b)). The double clip used had a claw length of 30 mm or more. A weight was attached to one of the double clips, and the total weight of the double clip to which the weight was attached and the weight was 110 g. In a room temperature atmosphere, a double clip without a weight was held, and the weight attached to the other double clip was lifted so as to float in the air, and the non-woven fabric was kept stretched by the weight of the double clip and the weight for 20 seconds. Immediately after that, the length of the non-woven fabric in the long side direction was measured while floating in the air (FIG. 17 (c)). Calculate the ratio using the following formula to determine how much the length after floating in the air is longer than the length of the long side after floating in the air and the length of the long side before floating in the air of 100 mm. The growth rate was used.
Figure JPOXMLDOC01-appb-M000005
Figure JPOXMLDOC01-appb-M000005
　＜不織布の厚み測定＞
　ダイヤルシックネスゲージ　大型タイプ（厚み測定器）（株式会社　尾崎製作所製、型番：Ｊ－Ｂ、測定子：アンビル上下φ５０ｍｍ）を用いて測定した。測定点数は、異なる箇所を５回とし、測定値は５点の平均値とした。厚み測定時は、不織布に圧力が出来るだけかからないよう、ハンドルからゆっくりと手を離し、厚みを測定した。 <Measurement of non-woven fabric thickness>
Dial thickness gauge Measured using a large type (thickness measuring instrument) (manufactured by Ozaki Seisakusho Co., Ltd., model number: JB, stylus: anvil top and bottom φ50 mm). The number of measurement points was 5 times at different points, and the measured value was an average value of 5 points. When measuring the thickness, the thickness was measured by slowly releasing the hand from the handle so that pressure was not applied to the non-woven fabric as much as possible.
　＜不織布の嵩密度の計算方法＞
　縦を１０ｃｍ以上、横を４０ｃｍ以上のサイズに切り取った不織布の重量を測定した。不織布の縦と横の長さ、および＜厚み測定＞より測り取った厚みをそれぞれ掛けて不織布の体積を計算し、不織布の重量を不織布の体積で割って嵩密度を計算した。 <Calculation method of bulk density of non-woven fabric>
The weight of the non-woven fabric cut into a size of 10 cm or more in length and 40 cm or more in width was measured. The volume of the non-woven fabric was calculated by multiplying the vertical and horizontal lengths of the non-woven fabric and the thickness measured from <thickness measurement>, respectively, and the bulk density was calculated by dividing the weight of the non-woven fabric by the volume of the non-woven fabric.
　＜不織布の液拡散面積の測定方法＞
　目開きが２ｍｍ、線形が０．９ｍｍの網を用いた直径３０ｃｍの篩を平面上に置き、１０ｃｍ四方に切り取った不織布（第２の基材）を置いた。１ｍｌのシリンジに口径０．５０ｍｍの注射針を装着して、青色１号試薬を２０ｐｐｍ含む生理食塩水１．００ｇを量りとり、篩上の不織布の中央にシリンジの生理食塩水を垂直に注入した。この時、篩の網と平面は十分に離れており、不織布と網を通過した生理食塩水は網に接しないようにした。不織布が生理食塩水を吸水して液の拡散が完了すると、生理食塩水が拡散している面積を測定した。 <Measurement method of liquid diffusion area of non-woven fabric>
A sieve having a diameter of 30 cm using a net having a mesh size of 2 mm and an alignment of 0.9 mm was placed on a flat surface, and a non-woven fabric (second base material) cut into 10 cm squares was placed. An injection needle having a diameter of 0.50 mm was attached to a 1 ml syringe, 1.00 g of physiological saline containing 20 ppm of Blue No. 1 reagent was weighed, and the physiological saline of the syringe was vertically injected into the center of the non-woven fabric on the sieve. .. At this time, the mesh of the sieve and the flat surface were sufficiently separated from each other so that the non-woven fabric and the physiological saline passing through the mesh did not come into contact with the mesh. When the non-woven fabric absorbed the physiological saline and the diffusion of the liquid was completed, the area where the physiological saline was diffused was measured.
　＜不織布に対する粒子状吸水剤の透過率＞
　目開き８５０μｍのメッシュ３２を有するＪＩＳ標準篩（Ｔｈｅ　ＩＩＤＡ　ＴＥＳＴＩＮＧ　ＳＩＥＶＥ：内径８０ｍｍ；ＪＩＳ　Ｚ８８０１－１（２０００））、またはＪＩＳ標準篩に相当する篩３１の中に、直径８０ｍｍに切断した不織布（第１の基材１１）を図５に示すように設置し、周囲をテープ３３でとめた（少なくとも直径７５ｍｍ以上は粒子が透過可能な面積を確保する）。不織布（第１の基材１１）は後述の方法により、吸水性シートから取り出したものを使用してもよい。篩３１の中の不織布（第１の基材１１）上（図５の矢印の方向）から、粒子状吸水剤１４（重量平均粒子径：３６７μｍ、粒度分布：８５０μｍ～６００μｍが６．１％　６００μｍ～５００μｍが１４．５％　５００μｍ～３００μｍが５０％　３００μｍ～１５０μｍが２７．６％　１５０μｍ～４５μｍが１．９％　４５μｍ以下０．１％）１０．０ｇを投入し、ロータップ型ふるい振盪機（株式会社飯田製作所製ＥＳ－６５型ふるい振盪機；回転数２３０ｒｐｍ、衝撃数１３０ｒｐｍ）を用いて、室温（２０～２５℃）、相対湿度５０％ＲＨの条件下で５分間振盪した。振盪後、不織布（第１の基材１１）と上記ＪＩＳ標準篩に相当する篩３１のメッシュ３２を通過した粒子状吸水剤１４（すなわち、篩３１のメッシュ３２より下部分３１ａに存在する粒子状吸水剤１４）の質量（Ｗ（ｇ））を測定し、下記式（ｉ）にしたがって、粒子状吸水剤１４の透過率を算出した。なお、測定は２回行い、その平均値を算出した。 <Transmittance of particulate water absorbent to non-woven fabric>
A JIS standard sieve (The IIDA TESTING SIEVE: inner diameter 80 mm; JIS Z8801-1 (2000)) having a mesh 32 with an opening of 850 μm, or a non-woven fabric cut to a diameter of 80 mm in a sieve 31 corresponding to the JIS standard sieve (No. 1). The base material 11) of No. 1 was installed as shown in FIG. 5, and the periphery was fastened with a tape 33 (at least a diameter of 75 mm or more secures an area through which particles can permeate). As the non-woven fabric (first base material 11), one taken out from the water-absorbent sheet by the method described later may be used. From the top of the non-woven fabric (first base material 11) in the sieve 31 (in the direction of the arrow in FIG. 5), the particulate water absorbent 14 (weight average particle diameter: 367 μm, particle size distribution: 850 μm to 600 μm is 6.1% 600 μm). ~ 500 μm is 14.5% 500 μm ~ 300 μm is 50% 300 μm ~ 150 μm is 27.6% 150 μm ~ 45 μm is 1.9% 45 μm or less 0.1%) 10.0 g is added and a low tap type sieve shaker (stock) Using an ES-65 type sieve shaker manufactured by Iida Seisakusho Co., Ltd .; rotation speed 230 rpm, impact number 130 rpm), the particles were shaken for 5 minutes under the conditions of room temperature (20 to 25 ° C.) and relative humidity of 50% RH. After shaking, the particulate water absorbing agent 14 (that is, particles existing in the portion 31a below the mesh 32 of the sieve 31) has passed through the non-woven fabric (first base material 11) and the mesh 32 of the sieve 31 corresponding to the JIS standard sieve. The mass (W (g)) of the water absorbing agent 14) was measured, and the transmittance of the particulate water absorbing agent 14 was calculated according to the following formula (i). The measurement was performed twice, and the average value was calculated.
Figure JPOXMLDOC01-appb-M000006
Figure JPOXMLDOC01-appb-M000006
　なお、上記透過率の測定に用いた粒子状吸水剤は、重量平均粒子径３００～４５０μｍ、粒度分布８５０μｍ～１５０μｍである粒子状吸水剤を９０重量％以上含んでなる粒子状吸水剤である。よって、本実施例で算出された第１の基材に対する粒子状吸水剤の透過率は、第１の基材に対する特定の粒子状吸水剤の透過率にも相当する。 The particulate water absorbent used for measuring the transmittance is a particulate water absorbent containing 90% by weight or more of the particulate water absorbent having a weight average particle diameter of 300 to 450 μm and a particle size distribution of 850 μm to 150 μm. Therefore, the transmittance of the particulate water-absorbing agent for the first base material calculated in this example also corresponds to the transmittance of the specific particulate water-absorbing agent for the first base material.
　＜吸水性シートからの粒子状吸水剤の取出し方法＞
　吸水性シートから上方不織布、および下方の不織布を剥がすことで粒子状吸水剤（中間不織布を含む場合は中間不織布と粒子状吸水剤と）を取り出した。上方および下方の不織布や中間不織布に貼着した粒子状吸水剤も全て取り出した。上方および下方の不織布を剥がす際には、吸水性シートを冷却し、不織布や粒子状吸水剤を貼着している接着剤（ホットメルト接着剤やスプレー糊）の接着性を十分に弱めた後に剥がした。この手順を踏むことで、不織布の繊維や構造厚みを変化させることなく取り出すことができ、正確に透過率を測定することが可能になる。吸水性シートの冷却方法は－１０℃以下の恒温槽に一定時間入れる、冷却スプレーを吹きかける、液体窒素をかける等、種々手段が考えられるが、不織布の繊維や構造、厚みを変化させることなく、かつ吸水性シートに含まれる粒子状吸水剤が吸湿しない条件で行うのであれば、特に限定されない。 <Method of removing the particulate water-absorbing agent from the water-absorbing sheet>
By peeling the upper non-woven fabric and the lower non-woven fabric from the water-absorbent sheet, the particulate water-absorbing agent (in the case of containing the intermediate non-woven fabric, the intermediate non-woven fabric and the particulate water-absorbing agent) was taken out. All the particulate water absorbents attached to the upper and lower non-woven fabrics and the intermediate non-woven fabric were also taken out. When peeling off the upper and lower non-woven fabrics, cool the water-absorbent sheet to sufficiently weaken the adhesiveness of the adhesive (hot melt adhesive or spray glue) to which the non-woven fabric or particulate water-absorbing agent is attached. I peeled it off. By following this procedure, the fibers of the non-woven fabric and the structural thickness can be taken out without changing, and the transmittance can be measured accurately. Various means can be considered for cooling the water-absorbent sheet, such as putting it in a constant temperature bath at -10 ° C or lower for a certain period of time, spraying a cooling spray, or spraying liquid nitrogen, but without changing the fiber, structure, or thickness of the non-woven fabric. Moreover, it is not particularly limited as long as it is carried out under the condition that the particulate water absorbing agent contained in the water absorbing sheet does not absorb moisture.
　また、取出した粒子状吸水剤が吸湿している場合、例えば乾燥することで、含水率を１０質量％以下、好ましくは５±２質量％に調整して、上記透過率や本願で規定する諸物性を測定すればよい。含水率を調整するための乾燥条件としては、吸水性樹脂（粒子状吸水剤）の分解や変性が生じない条件ならば特に限定されないが、好ましくは減圧乾燥が良い。 When the extracted particulate water absorbing agent absorbs moisture, for example, by drying, the water content is adjusted to 10% by mass or less, preferably 5 ± 2% by mass, and the above-mentioned transmittance and various specifications specified in the present application. Physical properties may be measured. The drying conditions for adjusting the water content are not particularly limited as long as the water-absorbent resin (particulate water-absorbing agent) is not decomposed or modified, but vacuum drying is preferable.
　＜上方不織布中における粒子状吸水剤の含有割合の測定＞
　上方不織布を縦１０ｍｍ、横１０ｍｍの正方形に切り取ったもの（厚みはそのまま）を、株式会社島津製作所製マイクロフォーカスＸ線ＣＴシステム　ｉｎｓｐｅＸｉｏ　ＳＭＸ－１００ＣＴにより測定を行った。測定条件を以下に記す。 <Measurement of content ratio of particulate water absorbent in upper non-woven fabric>
A square piece of the upper non-woven fabric having a length of 10 mm and a width of 10 mm (with the same thickness) was measured by a microfocus X-ray CT system inspexio SMX-100CT manufactured by Shimadzu Corporation. The measurement conditions are described below.
　［Ｘ線ＣＴによる撮影］
　画像横サイズ（ｐｉｘｅｌ）：５１２
　画像縦サイズ（ｐｉｘｅｌ）：５１２
　Ｘ線管電圧（ｋＶ）：５０
　Ｘ線管電流（μＡ）：４０
　インチサイズ（ｉｎｃｈ）：４．０
　Ｘ線フィルタ：なし
　ＳＤＤ（Ｘ線源の焦点とＸ線検出器の距離）（ｍｍ）：７００
　ＳＲＤ（Ｘ線源の焦点と測定試料の回転中心の距離）（ｍｍ）：５５０
　走査モード　１：ＣＢＣＴ
　走査モード　２：ノーマル走査
　走査角度：フル走査
　ビュー数：２４００
　アベレージ数：５
　スムージング：ＹＺ
　スライス厚（ｍｍ）：０．１６６
　ＢＨＣデータ：なし
　精細モード：あり
　ＦＯＶ　ＸＹ（最大撮影領域　ＸＹ）（ｍｍ）：５０．３
　ＦＯＶ　Ｚ（最大撮影領域　Ｚ）（ｍｍ）：４０．０。 [Shooting by X-ray CT]
Image horizontal size (pixel): 512
Image vertical size (pixel): 512
X-ray tube voltage (kV): 50
X-ray tube current (μA): 40
Inch size (inch): 4.0
X-ray filter: None SDD (distance between the focal point of the X-ray source and the X-ray detector) (mm): 700
SRD (distance between the focal point of the X-ray source and the center of rotation of the measurement sample) (mm): 550
Scanning mode 1: CBCT
Scan mode 2: Normal scan Scan angle: Full scan Number of views: 2400
Average number: 5
Smoothing: YZ
Slice thickness (mm): 0.166
BHC data: None Fine mode: Yes FOV XY (maximum shooting area XY) (mm): 50.3
FOV Z (maximum field of view Z) (mm): 40.0.
　次に、Ｘ線ＣＴの撮影データを、三谷商事株式会社製解析ソフト　Ｗｉｎ　ＲＯＯＦを用いて、以下のような手順で解析を行った。 Next, the X-ray CT imaging data was analyzed by the following procedure using the analysis software WinROOF manufactured by Mitani Corporation.
　（１）Ｗｉｎ　ＲＯＯＦを開き、Ｘ線ＣＴにて保存した解析したい画像（Ｊｐｅｇ）を選択する。 (1) Open Win ROOF and select the image (Jpeg) you want to analyze saved by X-ray CT.
　（２）画面上から２値処理、自動２値化、モード法、しきい値（適宜調整する）、実行という流れでクリック（選択）する。 (2) Click (select) from the screen in the flow of binary processing, automatic binarization, mode method, threshold value (adjust appropriately), and execution.
　（３）多角形ＲＯＩを選択し、第１の基材（上方不織布）中の粒子状吸水剤を囲み、粒子状吸水剤面積を計算させる。 (3) Select a polygonal ROI, surround the particulate water absorbent in the first base material (upper non-woven fabric), and have the particle water absorbent area calculated.
　（４）（３）と同様にして、吸水性シート中における粒子状吸水剤の総面積を計算する。 In the same manner as in (4) and (3), the total area of the particulate water absorbing agent in the water absorbing sheet is calculated.
　計算結果から、第１の基材中の粒子状吸水剤の含有割合（％）を下式により計算した。 From the calculation result, the content ratio (%) of the particulate water absorbing agent in the first base material was calculated by the following formula.
　第１の基材中の粒子状吸水剤の含有割合（％）＝第１の基材中の粒子状吸水剤面積（Ｉ）／粒子状吸水剤総面積（ＩＩ）×１００
　すなわち、第１の基材中の粒子状吸水剤の含有割合は、粒子状吸水剤の総面積に対する面積％で表される。なお、第１の基材の液を直接的に吸収する吸液面（上方不織布の吸収する液が導入される側の面）上には、粒子状吸水剤は、存在しても数％未満であるため、存在していないとみなすことができる。なお、下記の実施例においては、第１の基材中の粒子状吸水剤の含有割合が、吸水性シート全体に含有される粒子状吸水剤に対して、５％以上であった。 Content ratio (%) of particulate water-absorbing agent in the first base material = particle-like water-absorbing agent area (I) in the first base material / total particle-like water-absorbing agent area (II) × 100
That is, the content ratio of the particulate water absorbing agent in the first base material is represented by the area% with respect to the total area of the particulate water absorbing agent. The particulate water absorbent is less than a few percent even if it is present on the liquid absorbing surface that directly absorbs the liquid of the first base material (the surface on the side where the liquid to be absorbed by the upper non-woven fabric is introduced). Therefore, it can be considered that it does not exist. In the following examples, the content ratio of the particulate water absorbing agent in the first base material was 5% or more with respect to the particulate water absorbing agent contained in the entire water absorbing sheet.
　〔吸水性シートの評価方法〕
　＜逆戻り量（特定戻り量評価）＞
　図６に示されるように縦１０ｃｍ、横４０ｃｍに作製した吸水性シート１０を、縦１４ｃｍ、横４０ｃｍの液体不透過性シート２１で上部に開口部ができるように包んだ。液不透過性シート２１で包んだ吸水性シート１０を平面に置き、その上に液注入筒４１（図７）を図８に示されるように吸水性シート１０の中央に置いた。この状態で、流速７ｍｌ／秒で液投入が可能な漏斗４２を使用して液注入筒４１へ２３℃の０．９重量％塩化ナトリウム水溶液８０ｇを投入した（図９）。なお、この場合、シート２２において、液不透過性シート２１から露出した吸水性シート１０に対して、液が投入されている。液を投入してから１０分後、予め重量を測定した濾紙４３（型式Ｎｏ．２、ＡＤＶＡＮＴＥＣ製；直径１１０ｍｍの円形のもの）２０枚を、シート２２の中央、すなわち、吸水性シート１０の中央に載せ、直径１００ｍｍの円形の錘４４（１２００ｇ）をさらに載せて、１分間保持した。１分後、錘４４を除去し、濾紙４３の重量増分から逆戻り量１回目（ｇ）を測定した。錘４４を除去してから１分後、同様の操作（液を投入→投入１０分後、濾紙４３および錘４４（１２００ｇ）を載せて、１分間保持→１分後保持→錘を除去、逆戻り量の測定）を繰り返し、逆戻り量２回目（ｇ）、逆戻り量３回目（ｇ）を測定した。測定した逆戻り量の１回目から３回目までの合計を表４、表６に示した。 [Evaluation method of water-absorbent sheet]
<Reverse amount (specific return amount evaluation)>
As shown in FIG. 6, the water-absorbent sheet 10 produced in a length of 10 cm and a width of 40 cm was wrapped with a liquid-impermeable sheet 21 having a length of 14 cm and a width of 40 cm so as to have an opening at the top. The water-absorbent sheet 10 wrapped with the liquid-impermeable sheet 21 was placed on a flat surface, and the liquid injection cylinder 41 (FIG. 7) was placed on the water-absorbent sheet 10 in the center as shown in FIG. In this state, 80 g of a 0.9 wt% sodium chloride aqueous solution at 23 ° C. was charged into the liquid injection cylinder 41 using a funnel 42 capable of charging the liquid at a flow velocity of 7 ml / sec (FIG. 9). In this case, in the sheet 22, the liquid is charged into the water-absorbent sheet 10 exposed from the liquid-impermeable sheet 21. Ten minutes after the liquid was added, 20 sheets of filter paper 43 (model No. 2, manufactured by ADVANTEC; circular one having a diameter of 110 mm) whose weight was measured in advance were placed in the center of the sheet 22, that is, the center of the water-absorbent sheet 10. A circular weight 44 (1200 g) having a diameter of 100 mm was further placed on the surface and held for 1 minute. After 1 minute, the weight 44 was removed, and the first reversion amount (g) was measured from the weight increment of the filter paper 43. 1 minute after removing the weight 44, the same operation (adding the liquid → 10 minutes after adding the liquid, placing the filter paper 43 and the weight 44 (1200 g), holding for 1 minute → holding after 1 minute → removing the weight, reversing (Measurement of amount) was repeated, and the second reversion amount (g) and the third reversion amount (g) were measured. Tables 4 and 6 show the total of the measured reversion amounts from the first to the third.
　＜厚み比（Ｌｂ／Ｌａ）の算出方法＞
　Ｌａは、間隙における上方不織布の吸液面（第１の基材の吸液面）から下方不織布（第２の基材）の吸水層側の表面までの厚みであり、Ｌｂは、粒子状吸水剤が含まれる領域における上方不織布の吸液面（第１の基材の吸液面）から下方不織布（第２の基材）の吸水層側の表面までの厚みである。 <Calculation method of thickness ratio (Lb / La)>
La is the thickness from the liquid absorbing surface of the upper nonwoven fabric (liquid absorbing surface of the first substrate) to the surface of the lower nonwoven fabric (second substrate) on the water absorbing layer side in the gap, and Lb is the particulate water absorption. It is the thickness from the liquid-absorbing surface of the upper non-woven fabric (the liquid-absorbing surface of the first base material) to the surface of the lower non-woven fabric (the second base material) on the water-absorbing layer side in the region containing the agent.
　［Ｘ線ＣＴによる吸水性シートの厚み測定］
　Ｘ線ＣＴ　による吸水性シートの撮影は、縦３５０ｍｍで横１００ｍｍで厚み３ｍｍのプラスチック板に、長さ１８０ｍｍに切り取った吸水性シートの両端をガムテープで固定し、Ｘ線装置（島津製作所製、ｉｎｓｐｅＸｉｏ　ＳＭＸ－１００ＣＴ）内部プレート上に前記プラスチック板を厚み方向と垂直に設置し、下記条件で吸水性シートの中央を測定することにより撮影した。 [Measurement of water-absorbent sheet thickness by X-ray CT]
The water-absorbent sheet was photographed by X-ray CT by fixing both ends of the water-absorbent sheet cut to a length of 180 mm to a plastic plate 350 mm long, 100 mm wide and 3 mm thick with gum tape, and then using an X-ray device (manufactured by Shimadzu Corporation, inspeXio). SMX-100CT) The plastic plate was placed on the inner plate perpendicular to the thickness direction, and the center of the water-absorbent sheet was measured under the following conditions.
　使用装置：ｉｎｓｐｅＸｉｏ　ＳＭＸ－１００ＣＴ（島津製作所製）
　Ｘ線管電圧（ｋＶ）　：８０
　Ｘ線管電流（μＡ）　：４０
　インチサイズ（ｉｎｃｈ）　：４．０
　Ｘ線フィルタ　：なし
　ＳＯＤ（ｍｍ）　：７００
　ＳＲＤ（ｍｍ）　：５５０
　ビュー数　：２４００
　アベレージ数　：５×１
　スライス厚（ｍｍ）　：０．１６６
　ＣＴ　モード１　：ＣＢＣＴ
　ＣＴ　モード２　：ノーマル操作
　走査角度　：フル走査
　ＢＨＣ　データ　：なし
　センターアジャスト：あり
　精細モード　：あり
　ＦＯＶ（　ＸＹ）（ｍｍ）　：５０．３
　ＦＯＶ　（Ｚ）（ｍｍ）　：２０．０
　ボクセルサイズ（ｍｍ／ｖｏｘｅｌ）：０．０９８
　撮影して得られた立体映像を長さ方向に２０３分割した断面図を取得し、５０枚目、１００枚目、１５０枚目の画像から、吸水性シートの厚みを測り取った。厚みを測り取るとき、上層不織布下の間隙における上方不織布の吸液面から下方不織布の吸水層側の表面までの厚みをＬａとし、上層不織布下の粒子状吸水剤が含まれる領域における上方不織布の吸液面から下方不織布の吸水層側の表面までの厚みをＬｂとした。 Equipment used: inspexio SMX-100CT (manufactured by Shimadzu Corporation)
X-ray tube voltage (kV): 80
X-ray tube current (μA): 40
Inch size (inch): 4.0
X-ray filter: None SOD (mm): 700
SRD (mm): 550
Number of views: 2400
Number of averages: 5 x 1
Slice thickness (mm): 0.166
CT mode 1: CBCT
CT mode 2: Normal operation Scanning angle: Full scanning BHC data: None Center adjust: Yes Fine mode: Yes FOV (XY) (mm): 50.3
FOV (Z) (mm): 20.0
Voxel size (mm / voxel): 0.098
A cross-sectional view obtained by dividing the stereoscopic image obtained by photographing into 203 in the length direction was acquired, and the thickness of the water-absorbent sheet was measured from the 50th, 100th, and 150th images. When measuring the thickness, the thickness from the liquid-absorbing surface of the upper non-woven fabric to the surface of the lower non-woven fabric on the water-absorbing layer side in the gap under the upper non-woven fabric is La, and the thickness of the upper non-woven fabric in the region under the upper non-woven fabric containing the particulate water-absorbing agent is defined as La. The thickness from the liquid absorbing surface to the surface of the lower nonwoven fabric on the water absorbing layer side was defined as Lb.
　＜保形性の評価＞
　吸水性シートに対し、＜逆戻り量＞を評価した後、吸水性シートの中央を幅方向に切断し、粒子状吸水剤が含まれない領域（すなわち、間隙）を目視で確認した。この時、間隙に存在するものを確認し、以下の評価基準で評価した。
評価基準
〇：粒子状吸水剤が含まれる領域が、間隙により隔てられている
（すなわち、間隙にはいかなる部材も存在しない、または、間隙には吸水層を矜持する基材（すなわち、単層形態の場合は、上層不織布および下方不織布；二層形態の場合は、上方不織布、中間不織布および下方不織布）が主に存在する）
×：間隙の存在割合が少なく、並列する粒子状吸水剤が含まれる領域同士が、つながっている（間隙により隔てられていない）
（すなわち、間隙とされていた領域に粒子状吸水剤が入り込んだり、吸水層を矜持する基材の存在割合が少なくなっている）。 <Evaluation of shape retention>
After evaluating the <reverse amount> with respect to the water-absorbent sheet, the center of the water-absorbent sheet was cut in the width direction, and the region (that is, the gap) containing no particulate water-absorbent was visually confirmed. At this time, what was present in the gap was confirmed and evaluated according to the following evaluation criteria.
Evaluation Criteria 〇: The region containing the particulate water-absorbing agent is separated by a gap (that is, there is no member in the gap, or the gap is a substrate having a water-absorbing layer (that is, a single-layer form). In the case of, the upper non-woven fabric and the lower non-woven fabric; in the case of the two-layer form, the upper non-woven fabric, the intermediate non-woven fabric and the lower non-woven fabric) are mainly present.
X: Regions containing a small amount of gaps and parallel particulate water absorbents are connected (not separated by gaps).
(That is, the particulate water-absorbing agent enters the region that was the gap, and the proportion of the base material that holds the water-absorbing layer is reduced).
　下記表３～表６に、実施例１～１０および比較例１～４で製造した吸水性シートの構成と、各吸水性シートで用いた基材の物性の評価結果、吸水性シートの評価結果を示す。なお、表３～表６中、ＳＡＰとは、粒子状吸水剤を意味する。また、表３および表５におけるＳＡＰ配置領域（％）とは、上方不織布の面方向において、粒子状吸水剤が配置された基材の全面積に対する粒子状吸水剤が含まれる領域の面積割合であり、ＳＡＰ非配置領域（％）とは、上方不織布の面方向において、粒子状吸水剤が配置された基材の全面積に対する粒子状吸水剤が含まれない領域（すなわち、間隙）の面積割合を意味する。ここで、粒子状吸水剤が配置された基材とは、粒子状吸水剤を散布した基材を意味する。なお、本実施例では、上方不織布、中間不織布および下方不織布は同じサイズである。 Tables 3 to 6 below show the configurations of the water-absorbent sheets produced in Examples 1 to 10 and Comparative Examples 1 to 4, the evaluation results of the physical properties of the base material used in each water-absorbent sheet, and the evaluation results of the water-absorbent sheet. Is shown. In Tables 3 to 6, SAP means a particulate water absorbing agent. Further, the SAP arrangement region (%) in Tables 3 and 5 is the area ratio of the region containing the particulate water absorbent to the total area of the base material on which the particulate water absorbent is arranged in the plane direction of the upper non-woven fabric. The SAP non-arranged region (%) is the area ratio of the region (that is, the gap) not containing the particulate water-absorbing agent to the total area of the base material on which the particulate water-absorbing agent is arranged in the plane direction of the upper non-woven fabric. Means. Here, the base material on which the particulate water absorbing agent is arranged means a base material on which the particulate water absorbing agent is sprayed. In this embodiment, the upper non-woven fabric, the intermediate non-woven fabric, and the lower non-woven fabric have the same size.
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000007
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000008
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000009
Figure JPOXMLDOC01-appb-T000010
Figure JPOXMLDOC01-appb-T000010
　以上の結果より、実施例２～１０の吸水性シートは、比較例１～４の吸水性シートと比較して、保形性が高く、かつ、逆戻り量が顕著に少なかった。すなわち、単層形態および二層形態の吸水性シートにおいて、伸縮性を有する上方不織布を用いて、吸水層において間隙を設けることにより、逆戻り量を低減でき、保形性が高いことが確認できた。 From the above results, the water-absorbent sheets of Examples 2 to 10 had higher shape retention and a significantly smaller amount of reversion as compared with the water-absorbent sheets of Comparative Examples 1 to 4. That is, it was confirmed that in the single-layer and two-layer water-absorbent sheets, the amount of reversion can be reduced and the shape-retaining property is high by providing a gap in the water-absorbent layer by using an upper non-woven fabric having elasticity. ..
　また、本実施形態においては、二層形態は単層形態に比べて、逆戻り量が多くなる傾向にある。これは、二層形態の上層不織布に対する粒子状吸水剤の量（すなわち、上方不織布と中間不織布との間に位置する粒子状吸水剤の量）が、単層形態の上層不織布に対する粒子状吸水剤の量（すなわち、上方不織布と下方不織布との間に位置する粒子状吸水剤の量）よりも少ないことも要因のひとつでありうる。そのため、単層形態と二層形態との逆戻り量の低減効果の差は一概に比較することは難しいと考える。 Further, in the present embodiment, the amount of reversion tends to be larger in the two-layer form than in the single-layer form. This is because the amount of the particulate water-absorbing agent for the two-layered upper-layer non-woven fabric (that is, the amount of the particulate water-absorbing agent located between the upper nonwoven fabric and the intermediate nonwoven fabric) is the particulate water-absorbing agent for the single-layered upper-layer nonwoven fabric. (That is, the amount of the particulate water-absorbing agent located between the upper non-woven fabric and the lower non-woven fabric) may be one of the factors. Therefore, it is difficult to make a general comparison of the difference in the effect of reducing the amount of reversion between the single-layer form and the two-layer form.
　なお、本出願は、２０１９年１１月２８日に出願された日本特許出願第２０１９－２１５８８７号および２０１９年１１月２８日に出願された日本特許出願第２０１９－２１５８８８号に基づいており、その開示内容は、参照により全体として引用されている。
［符号の説明］
１０　　吸水性シート
１１　　第１の基材、
１２　　吸水層、
１３　　第２の基材、
１４　　粒子状吸水剤、
１５　　間隙、
１６　　ラッピングシート、
２１　　液体不透過シート、
３１　　篩、
３１ａ　篩のメッシュより下部分、
３２　　メッシュ、
３３　　テープ、
４１　　液注入筒、
４２　　漏斗、
６０　　架台、
６１　　パイプ、
６３　　アクリル板、
６４　　漏斗、
６５　　金属製トレイ。 This application is based on Japanese Patent Application No. 2019-2158887 filed on November 28, 2019 and Japanese Patent Application No. 2019-215888 filed on November 28, 2019, and disclosure thereof. The content is cited as a whole by reference.
[Explanation of code]
10 Water-absorbent sheet 11 First base material,
12 Water absorption layer,
13 Second base material,
14 Particle-like water absorbent,
15 gaps,
16 wrapping sheet,
21 Liquid opaque sheet,
31 sieve,
31a Below the mesh of the sieve,
32 mesh,
33 tape,
41 Liquid injection tube,
42 funnel,
60 pedestals,
61 pipe,
63 Acrylic board,
64 funnel,
65 Metal tray.
　［第２の発明］
　続いて、第２の発明の説明を行う。第２の発明の吸水性シートは、第１の基材と、第２の基材と、前記第１の基材と、前記第２の基材との間に位置する吸水層と、を有する、吸水性シートであって、前記吸水層は、粒子状吸水剤を含み、前記粒子状吸水剤が含まれる領域が、実質的に前記粒子状吸水剤を含まない間隙を隔てて配置され、前記第１の基材の表面は、液を直接的に吸収する吸液面を形成し、前記第１の基材は、伸び率が１０％以上である。
［書類名］明細書
　［発明の名称］吸水性シートおよびそれを含む吸収性物品
　［技術分野］
　本発明は、吸水性シートおよびそれを含む吸収性物品に関する。 [Second invention]
Subsequently, the second invention will be described. The water-absorbent sheet of the second invention has a first base material, a second base material, and a water-absorbent layer located between the first base material and the second base material. In the water-absorbing sheet, the water-absorbing layer contains a particulate water-absorbing agent, and a region containing the particulate water-absorbing agent is arranged with a gap substantially free of the particulate water-absorbing agent. The surface of the first base material forms a liquid absorbing surface that directly absorbs the liquid, and the first base material has an elongation rate of 10% or more.
[Document name] Specification [Title of invention] Water-absorbent sheet and absorbent article containing the same [Technical field]
The present invention relates to a water-absorbent sheet and an absorbent article containing the same.
　［背景技術］
　吸水性樹脂（ＳＡＰ／Ｓｕｐｅｒ　Ａｂｓｏｒｂｅｎｔ　ｐｏｌｙｍｅｒ）は、水膨潤性水不溶性の高分子ゲル化剤であり、紙オムツ、生理用ナプキンや成人向け失禁用製品等の衛生材料、農園芸用の土壌保水剤、工業用の止水剤等、様々な用途に利用されている。 [Background technology]
Water-absorbent resin (SAP / Super Absorbent polymer) is a water-swellable water-insoluble polymer gelling agent, which is a sanitary material such as disposable diapers, sanitary napkins and incontinence products for adults, and a soil water-retaining agent for agriculture and gardening. , Industrial water-stopping agent, etc., are used for various purposes.
　これら吸収性物品は一般に紙オムツ製造工場にて吸水性樹脂と繊維材料を混合して吸収性物品ごとに個々に型取りした吸収体として製造されており、目的に応じて種々の形状の吸収体（例えば、平面に見て砂時計型、キツネ型、楕円型等）に加工されている。これら吸収体の製造方法は個々に型取りするため任意の形に加工でき、吸収性物品ごとに繊維や吸水性樹脂の量も調整し易いため、現在の紙オムツの主流となっている。 These absorbent articles are generally manufactured in a paper diaper manufacturing factory as an absorber in which a water-absorbent resin and a fiber material are mixed and individually molded for each absorbent article, and have various shapes depending on the purpose. (For example, it is processed into an hourglass type, a diaper type, an oval type, etc. when viewed on a flat surface). Since these absorbents are individually molded, they can be processed into any shape, and the amount of fibers and water-absorbent resin can be easily adjusted for each absorbent article, which is the mainstream of the current paper diapers.
　しかし、近年、紙オムツの製造で、２枚のシート間に吸水性樹脂を固定化した長尺の吸水性シートを衛生材料の製造工程で裁断した吸収体（吸水性シートと呼称、通常は幅１０ｃｍ前後で長さ数１０ｃｍの長方形に裁断）を用いた紙オムツが製造されるようになってきた。紙オムツメーカーは、長尺の連続吸水性シートを購入または製造することで、紙オムツの製造工程を簡便化でき、さらにパルプを用いないことで紙オムツを薄型化することができる。吸水性シートは上下のシート（特に不織布シート）間に吸水性樹脂粒子をサンドイッチおよび固定化する構成をとり、通常長尺連続シートを製造した後に長尺連続シートを裁断して幅１０ｃｍ前後で長さ数１０ｃｍの長方形とし、紙オムツに組み込む（例えば、国際公開第２０１０／１４３６３５号）。 However, in recent years, in the manufacture of paper omelets, an absorber (called a water-absorbent sheet, usually width) obtained by cutting a long water-absorbent sheet in which a water-absorbent resin is immobilized between two sheets in the manufacturing process of a sanitary material. Paper omelets using (cut into a rectangle with a length of about 10 cm and a length of several tens of centimeters) have come to be manufactured. Paper diaper makers can simplify the manufacturing process of paper diapers by purchasing or manufacturing long continuous water-absorbent sheets, and can make paper diapers thinner by not using pulp. The water-absorbent sheet has a structure in which water-absorbent resin particles are sandwiched and fixed between the upper and lower sheets (particularly a non-woven fabric sheet), and after usually producing a long continuous sheet, the long continuous sheet is cut to have a width of about 10 cm. Make a rectangle with a length of several tens of centimeters and incorporate it into a paper diaper (for example, International Publication No. 2010/143635).
　従来の衛生材料（紙オムツ）と違って、吸水性シートによる紙オムツはその歴史が浅いこともあり、吸水性シートに適した吸水性樹脂の開発やパラメーターの提案は殆ど行われていないのが実情であり、従来の紙オムツ向けの吸水性樹脂が吸水性シートにもそのまま使用されている。 Unlike conventional sanitary materials (paper diapers), paper diapers made of water-absorbent sheets have a short history, and there have been few developments of water-absorbent resins suitable for water-absorbent sheets or proposals for parameters. As a matter of fact, the conventional water-absorbent resin for disposable diapers is used as it is for the water-absorbent sheet.
　［発明の概要］
　［発明が解決しようとする課題］
　本発明者らは、薄型であることが主流の吸水性シートならではの構造上、吸収された液体が、吸水性シートに圧力が加わることにより吸収される液の導入方向に放出される、いわゆる「逆戻り」が生じやすいことを知見した。「逆戻り」はＲｅ－ｗｅｔとも呼ばれる。そして、逆戻り量の発生は、断続的に複数回（特に、３回以上）の液の導入があって液の導入量が多くなると、その問題が顕著であることを見出した。逆戻りが生じた場合、吸水性シートと接している肌はその逆戻りした液と接するため、湿気の高い状態に晒される。そのため、使用者は不快感を生じるだけでなく、吸水性シートと接している肌にかぶれも生じやすくなる。 [Outline of Invention]
[Problems to be solved by the invention]
Due to the structure unique to the water-absorbent sheet, which is mainly thin, the present inventors release the absorbed liquid in the introduction direction of the absorbed liquid when pressure is applied to the water-absorbent sheet. It was found that "backtracking" is likely to occur. "Return" is also called Re-wet. Then, it was found that the problem of the occurrence of the reversion amount becomes remarkable when the liquid is introduced intermittently a plurality of times (particularly three times or more) and the liquid introduction amount is large. When reversion occurs, the skin in contact with the water-absorbent sheet comes into contact with the reverted liquid and is exposed to a high humidity condition. Therefore, the user not only causes discomfort, but also tends to cause a rash on the skin in contact with the water-absorbent sheet.
　また、このような従来の吸水性シートの構成では、吸液した吸水性樹脂粒子が膨潤することによって、吸水性樹脂粒子の上下シートに対する固定が弱まり、吸水性樹脂粒子がシート内で移動してしまう場合がある。そうすると、シート内で吸水性樹脂粒子の偏りが生じ、吸水性シートの形状が崩れる。この場合、吸水性シートの液吸収性に偏りが生じることになり、漏れの原因となる。場合によっては、吸水性樹脂粒子がシート内から外部へ脱落してしまうこともある。 Further, in such a conventional structure of the water-absorbent sheet, the water-absorbent resin particles swell to weaken the fixation of the water-absorbent resin particles to the upper and lower sheets, and the water-absorbent resin particles move in the sheet. It may end up. Then, the water-absorbent resin particles are biased in the sheet, and the shape of the water-absorbent sheet is deformed. In this case, the liquid absorbency of the water-absorbent sheet becomes uneven, which causes leakage. In some cases, the water-absorbent resin particles may fall off from the inside of the sheet to the outside.
　本発明は、上記事情に鑑みてなされたものであり、断続的に複数回（特に、３回以上）の液の導入があっても、逆戻りによる吸水性シートからの液放出を有意に低減することができ、かつ、液吸収後であってもシート形状が保持される（シートの保形性が高い）新規な吸水性シートを提供することを目的とする。 The present invention has been made in view of the above circumstances, and even if the liquid is intermittently introduced a plurality of times (particularly three or more times), the liquid discharge from the water-absorbent sheet due to reversion is significantly reduced. It is an object of the present invention to provide a novel water-absorbent sheet capable of maintaining the sheet shape (highly shape-retaining property of the sheet) even after liquid absorption.
　［課題を解決するための手段］
　本発明者らは、上記課題を解決するために、鋭意検討を積み重ねた。その結果、第１の基材と、第２の基材と、前記第１の基材と、前記第２の基材との間に位置する吸水層と、を有する、吸水性シートであって、前記吸水層は、粒子状吸水剤を含み、前記粒子状吸水剤が含まれる領域が、実質的に前記粒子状吸水剤を含まない間隙を隔てて配置され、前記第１の基材の表面が、液を直接的に吸収する吸液面を形成し、前記第１の基材は、伸び率が１０％以上である、吸水性シートにより、上記課題が解決することを見出した。 [Means to solve problems]
The present inventors have made extensive studies in order to solve the above problems. As a result, it is a water-absorbent sheet having a first base material, a second base material, a water-absorbing layer located between the first base material and the second base material. The water-absorbing layer contains the particulate water-absorbing agent, and the region containing the particulate water-absorbing agent is arranged with a gap substantially free of the particulate water-absorbing agent, and the surface of the first base material is formed. However, it has been found that the above-mentioned problem can be solved by a water-absorbent sheet which forms a water-absorbing surface that directly absorbs the liquid and has an elongation rate of 10% or more for the first base material.
　また、本発明の他の形態に係る吸水性シートは、前記吸水性シートにおいて、前記吸水層の上に前記第１の基材を積層した積層体のみが、前記第２の基材の上に、積層されてなる。 Further, in the water-absorbent sheet according to another embodiment of the present invention, in the water-absorbent sheet, only the laminate in which the first base material is laminated on the water-absorbent layer is on the second base material. , Laminated.
　さらに、本発明の他の形態に係る吸水性シートは、前記吸水性シートにおいて、前記吸水層の上に前記第１の基材を積層した積層体と、前記吸水層の上に中間基材を積層した構成体と、が、前記第２の基材の上に、積層されてなる。 Further, the water-absorbent sheet according to another embodiment of the present invention includes a laminated body in which the first base material is laminated on the water-absorbent layer and an intermediate base material on the water-absorbent layer. The laminated structure is laminated on the second base material.
　［図面の簡単な説明］
　　［図１８］本発明の第１の実施形態に係る吸水性シートの断面を表す模式図である。 [Simple description of drawings]
FIG. 18 is a schematic view showing a cross section of a water-absorbent sheet according to the first embodiment of the present invention.
　　［図１９］本発明の第２の実施形態に係る吸水性シートの断面を表す模式図である。 [FIG. 19] FIG. 19 is a schematic view showing a cross section of a water-absorbent sheet according to a second embodiment of the present invention.
　　［図２０］実施例で作製した吸水性シートにおける粒子状吸水剤と間隙との形態を説明するための吸水性シートの断面を表す模式図である。 [Fig. 20] Fig. 20 is a schematic view showing a cross section of the water-absorbent sheet for explaining the morphology of the particulate water-absorbent and the gap in the water-absorbent sheet produced in the example.
　　［図２１］実施例で作製した吸水性シートにおける粒子状吸水剤と間隙との形態を説明するための吸水性シートの断面を表す模式図である。 [FIG. 21] FIG. 21 is a schematic view showing a cross section of the water-absorbent sheet for explaining the morphology of the particulate water-absorbent and the gap in the water-absorbent sheet produced in the example.
　　［図２２］不織布の伸び率を測定する方法を説明する模式図である。 [FIG. 22] It is a schematic diagram explaining a method of measuring the elongation rate of a non-woven fabric.
　　［図２３］不織布に対する粒子状吸水剤の透過率を測定する方法を説明する模式図である。 [FIG. 23] FIG. 23 is a schematic diagram illustrating a method of measuring the transmittance of a particulate water absorbing agent with respect to a non-woven fabric.
　　［図２４］逆戻り量の評価に用いたサンプルを示した平面図および右側面図であり、実施例で作製した吸水性シートを液体不透過性シートで包む様子を示した図である。 [FIG. 24] It is a plan view and a right side view showing a sample used for evaluating the amount of reversion, and is a view showing how the water-absorbent sheet produced in the example is wrapped with a liquid-impermeable sheet.
　　［図２５］逆戻り量の評価に用いた液注入筒の平面図および正面図である。 [FIG. 25] It is a plan view and a front view of the liquid injection cylinder used for evaluating the amount of reversion.
　　［図２６］本願の実施例で用いた吸水性シートの上に液注入筒を置いた様子を示した正面図である。 [Fig. 26] is a front view showing a state in which a liquid injection cylinder is placed on the water-absorbent sheet used in the embodiment of the present application.
　　［図２７］漏斗を使用して液注入筒から塩化ナトリウム水溶液を吸水性シートに投入している様子を示した正面図である。 [Fig. 27] It is a front view showing a state in which an aqueous sodium chloride solution is poured into a water-absorbent sheet from a liquid injection cylinder using a funnel.
　［発明を実施するための形態］
　以下、本発明を最良の形態を示しながら説明する。本明細書の全体にわたり、単数形の表現は、特に言及しない限り、その複数形の概念をも含むことが理解されるべきである。従って、単数形の冠詞（例えば、英語の場合は「ａ」、「ａｎ」、「ｔｈｅ」等）は、特に言及しない限り、その複数形の概念をも含むことが理解されるべきである。また、本明細書において使用される用語は、特に言及しない限り、当該分野で通常用いられる意味で用いられることが理解されるべきである。したがって、他に定義されない限り、本明細書中で使用される全ての専門用語および科学技術用語は、本発明の属する分野の当業者によって一般的に理解されるのと同じ意味を有する。矛盾する場合、本明細書（定義を含めて）が優先する。本発明は、下記の実施形態に限定されるものではなく、特許請求の範囲内で種々改変することができる。 [Mode for carrying out the invention]
Hereinafter, the present invention will be described while showing the best mode. Throughout the specification, it should be understood that the singular representation also includes its plural concept, unless otherwise stated. Therefore, it should be understood that singular articles (eg, "a", "an", "the", etc. in English) also include the plural concept unless otherwise noted. It should also be understood that the terms used herein are used in the meaning commonly used in the art unless otherwise noted. Thus, unless otherwise defined, all terminology and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. In case of conflict, this specification (including definitions) takes precedence. The present invention is not limited to the following embodiments, and various modifications can be made within the scope of the claims.
　〔１．用語の定義〕
　第１の発明における［１－１．吸水性シート］、［１－２．吸水性樹脂］、［１－３．吸水剤、粒子状吸水剤］、［１－４．ポリアクリル酸（塩）］、［１－５．ＥＤＡＮＡおよびＥＲＴ］、［１－６．その他］の定義は、第２の発明においても同様に適用される。そのため、ここでは省略するが、これらの定義は、参照により第２の発明に組みこまれる。 [1. Definition of terms〕
In the first invention [1-1. Water-absorbent sheet], [1-2. Water-absorbent resin], [1-3. Water-absorbing agent, particulate water-absorbing agent], [1-4. Polyacrylic acid (salt)], [1-5. EDANA and ERT], [1-6. Others] applies similarly to the second invention. Therefore, although omitted here, these definitions are incorporated into the second invention by reference.
　〔２．吸水性シート〕
　本発明の吸水性シートは、第１の基材と、第２の基材と、前記第１の基材と、前記第２の基材との間に位置する吸水層と、を有する、吸水性シートであって、前記吸水層は、粒子状吸水剤を含み、前記粒子状吸水剤が含まれる領域が、実質的に前記粒子状吸水剤を含まない間隙を隔てて配置され、前記第１の基材の表面が、液を直接的に吸収する吸液面を形成し、前記第１の基材は、伸び率が１０％以上である。 [2. Water-absorbent sheet]
The water-absorbent sheet of the present invention has a first base material, a second base material, and a water-absorbent layer located between the first base material and the second base material. In the sex sheet, the water-absorbing layer contains a particulate water-absorbing agent, and a region containing the particulate water-absorbing agent is arranged with a gap substantially free of the particulate water-absorbing agent. The surface of the base material forms a water-absorbing surface that directly absorbs the liquid, and the first base material has an elongation rate of 10% or more.
　かかる構成によって、断続的に複数回（特に、３回以上）の液の導入があって液の導入量が多くなっても、逆戻りによる吸水性シートからの液放出を有意に低減することができ、かつ、吸液後の保形性が高い。本発明の吸水性シートは、液を直接的に吸収する吸液面を形成する第１の基材の伸び率が、１０％以上である。すなわち、第１の基材は伸縮性を有する。この伸縮性を有する第１の基材の表面に、液を直接的に吸収する吸液面が形成される。ここで、本明細書中、「吸液面」とは、その基材において液を吸収する側の面、すなわち、液が導入される側の表面を意味する。また、本明細書中、「直接的」とは、他の基材等を浸透してきた液を順次吸収する形態を含まない。なお、本明細書中、第１の基材の表面に後述のラッピングシートが配置された場合も、第１の基材の表面が、液を直接的に吸収する吸液面を形成する形態に包含される。 With such a configuration, even if the liquid is introduced intermittently a plurality of times (particularly three times or more) and the amount of the liquid introduced is large, the liquid discharge from the water-absorbent sheet due to reversion can be significantly reduced. Moreover, it has high shape retention after absorbing liquid. In the water-absorbent sheet of the present invention, the elongation rate of the first base material forming the liquid-absorbing surface that directly absorbs the liquid is 10% or more. That is, the first base material has elasticity. A liquid absorbing surface that directly absorbs the liquid is formed on the surface of the first stretchable base material. Here, in the present specification, the "liquid absorbing surface" means the surface of the base material on the side that absorbs the liquid, that is, the surface on the side where the liquid is introduced. Further, in the present specification, "directly" does not include a form in which a liquid that has permeated another base material or the like is sequentially absorbed. In the present specification, even when the wrapping sheet described later is arranged on the surface of the first base material, the surface of the first base material forms a liquid absorbing surface that directly absorbs the liquid. Included.
　本発明の第１の形態において、第１の基材の表面が液を直接的に吸収する吸液面であるため、第１の基材上には吸水層が配置されていない。よって、本発明の一実施形態に係る吸水性シートは、第１の基材と、第２の基材と、前記第１の基材と、前記第２の基材との間に位置する吸水層と、を有する、吸水性シートであって、前記吸水層は、粒子状吸水剤を含み、前記第１の基材上には吸水層が配置されておらず、前記粒子状吸水剤が含まれる領域が、実質的に前記粒子状吸水剤を含まない間隙を隔てて配置され、前記第１の基材は、伸び率が１０％以上である。本形態において、吸水層に含有されていた粒子状吸水剤の一部が第１の基材を透過して第１の基材上に移動して一部露出しても、それは吸水層が配置されているとはみなさない。なお、当該移動の要因は、例えば、吸水性シートが最終製品となり、輸送や運搬がなされて生じた振動などが想定される。前記第１の基材上に粒子状吸水剤を意図的に散布または配置したような場合は、本形態の範疇ではない。 In the first embodiment of the present invention, since the surface of the first base material is a liquid absorbing surface that directly absorbs the liquid, the water absorbing layer is not arranged on the first base material. Therefore, the water-absorbent sheet according to the embodiment of the present invention absorbs water located between the first base material, the second base material, the first base material, and the second base material. A water-absorbing sheet having a layer, wherein the water-absorbing layer contains a particulate water-absorbing agent, the water-absorbing layer is not arranged on the first base material, and the particulate water-absorbing agent is contained. The regions are arranged with a gap substantially free of the particulate water absorbing agent, and the first base material has an elongation rate of 10% or more. In this embodiment, even if a part of the particulate water-absorbing agent contained in the water-absorbing layer permeates the first base material and moves onto the first base material and is partially exposed, the water-absorbing layer is arranged. Not considered to be done. It is assumed that the cause of the movement is, for example, vibration generated when the water-absorbent sheet is the final product and is transported or transported. When the particulate water absorbing agent is intentionally sprayed or arranged on the first base material, it is not in the category of this embodiment.
　本発明者らは、従来の吸水性シート（例えば、中国特許出願公開第１０５３８０７５２号公報に記載の吸水性シートのように、第１の基材と第２の基材との間に位置する吸水層においてガイド溝（間隙に相当）を設けた吸水性シート）においては、本願の実施例における特定条件での逆戻り量の測定（本明細書中、「特定戻り量評価」とも称する）において、逆戻り量が低減できても保形性が悪いことを見出した。 The present inventors have a conventional water-absorbing sheet (for example, a water-absorbing sheet located between a first base material and a second base material, such as the water-absorbing sheet described in Japanese Patent Application Publication No. 105380752). In the water-absorbent sheet provided with a guide groove (corresponding to a gap) in the layer, in the measurement of the amount of reversion under specific conditions (also referred to as "specific return amount evaluation" in the present specification) in the embodiment of the present application, reversion is performed. It was found that the shape retention was poor even if the amount could be reduced.
　ここで、粒子状吸水剤が含まれる領域の間に存在する間隙は、液の導入があった場合に、第１の基材から吸水層へと液が導入される際の通液路として機能することができる。すなわち、通液路が存在することにより、吸液面より導入された液を、吸液面上に滞留することなく（さらには、導入した液が局所的に滞ることなく）、吸水機能を担う下層の吸水層に液を効率的に送り込むことができる。具体的には、第１の基材中を通過した液（例えば、尿）が、吸水層の表面全体と間隙とに導入される。間隙に導入された液は、粒子状吸水剤が含まれる領域に対し、通液を妨げる粒子状吸水剤がなく、粒子状吸水剤による吸収も緩やかであるため、拡散しやすくなる。液が拡散した結果、液を導入した部位の粒子状吸水剤の液吸収量が多く、液導入部から離れた部位の粒子状吸水剤の液吸収量が少なくなるといった、液の吸収量に偏りが生まれることを防止する。このため、粒子状吸水剤が飽和膨潤した部位が発生する、つまり、液を吸収できない部位が発生して逆戻り量が増加するといった作用を防止することができる。よって、結果として、逆戻り量が低減できるものと考えられる。 Here, the gap existing between the regions containing the particulate water-absorbing agent functions as a liquid passage when the liquid is introduced from the first base material to the water-absorbing layer when the liquid is introduced. can do. That is, due to the existence of the liquid passage, the liquid introduced from the liquid absorption surface does not stay on the liquid absorption surface (furthermore, the introduced liquid does not stay locally) and has a water absorption function. The liquid can be efficiently delivered to the lower water absorption layer. Specifically, the liquid (for example, urine) that has passed through the first base material is introduced into the entire surface of the water absorption layer and the gaps. The liquid introduced into the gap has no particulate water-absorbing agent that hinders the passage of the liquid with respect to the region containing the particulate water-absorbing agent, and is absorbed slowly by the particulate water-absorbing agent, so that it is easy to diffuse. As a result of the diffusion of the liquid, the amount of liquid absorbed by the particulate water-absorbing agent at the site where the liquid was introduced is large, and the amount of liquid absorbed by the particulate water-absorbing agent at the site away from the liquid-introduced part is small. Prevents the birth of. Therefore, it is possible to prevent an action such that a portion where the particulate water absorbing agent is saturated and swollen is generated, that is, a portion where the liquid cannot be absorbed is generated and the amount of reversion is increased. Therefore, as a result, it is considered that the amount of reversion can be reduced.
　しかしながら、例えば、粒子状吸水剤が液を吸収して膨潤した場合、粒子状吸水剤が含まれる領域はその体積が増加するため、間隙とされていた領域まで膨潤した粒子状吸水剤が侵入し、間隙が減少してしまう。この場合、断続的に複数回の液の導入があると、間隙の減少に応じて徐々に液の吸収能力が低下することが考えられる。そして、吸水層から液が放出される場合は、間隙の減少に伴い、間隙を液が通過しにくくなり、粒子状吸水剤が部分的に飽和膨潤しやすくなるため、第１の基材の吸液面まで逆戻りする量が徐々に増加していくことになる。これにより、逆戻りした液が肌まで上がる（肌に接する）ことになり、不快感を生じることになる。 However, for example, when the particulate water-absorbing agent absorbs the liquid and swells, the volume of the region containing the particulate water-absorbing agent increases, so that the swelled particulate water-absorbing agent invades into the region that was the gap. , The gap is reduced. In this case, if the liquid is introduced intermittently a plurality of times, it is considered that the liquid absorption capacity gradually decreases as the gap decreases. When the liquid is discharged from the water-absorbing layer, as the gap decreases, it becomes difficult for the liquid to pass through the gap, and the particulate water-absorbing agent tends to partially saturate and swell, so that the first base material absorbs the liquid. The amount of water returning to the liquid level will gradually increase. As a result, the retreated liquid rises to the skin (contacts the skin), causing discomfort.
　また、従来の吸水層に間隙を有する吸水性シート（例えば、中国特許出願公開第１０５３８０７５２号公報に記載の吸水性シート）の構成では、この粒子状吸水剤の膨潤により、第１の基材および／または第２の基材に対する粒子状吸水剤の固定が弱まり、粒子状吸水剤が吸水層内で移動してしまう場合がある。そうすると、吸水層内で粒子状吸水剤の偏りが生じ、吸水性シートの形状が崩れる（保形性が低下する）。 Further, in the configuration of the conventional water-absorbing sheet having a gap in the water-absorbing layer (for example, the water-absorbing sheet described in Japanese Patent Application Publication No. 105380752), the swelling of the particulate water-absorbing agent causes the first base material and / Or the fixation of the particulate water-absorbing agent to the second substrate may be weakened, and the particulate water-absorbing agent may move in the water-absorbing layer. Then, the particulate water-absorbing agent is biased in the water-absorbing layer, and the shape of the water-absorbing sheet collapses (shape retention is lowered).
　これに対し、本発明の吸水性シートは、第１の基材が伸縮性を有することにより、この粒子状吸水剤が含まれる領域の体積の増加を緩衝することができると考えられる。すなわち、粒子状吸水剤が膨潤した場合、その膨潤に応じて第１の基材が伸びることにより、間隙の減少を抑制でき、よって、間隙の形状を維持することができる。これにより、断続的に複数回の液の導入があっても、液の拡散能力が低下することなく、逆戻り量を低減できる。また、第１の基材が伸縮することにより粒子状吸水剤の膨潤を緩衝するため、第１の基材および／または第２の基材に対する粒子状吸水剤の固定が弱まることがない。具体的には、粒子状吸水剤と接する第１の基材は、粒子状吸水剤が膨潤することにより、膨潤した粒子状吸水剤に追随した形状に伸びる。これにより、第１の基材と粒子状吸水剤とが絡みあうことになり、粒子状吸水剤は第１の基材と第２の基材との間により強く保持される。よって、本発明の吸水性シートは、粒子状吸水剤が吸水層内の粒子状吸水剤が含まれる領域から移動することを抑制することができ、吸水性シートの形状を維持することができるため、保形性が高い。なお、本発明の実施形態においては、吸水層の上に第１の基材を積層した積層体と、吸水層の上に中間基材を積層した構成体と、が、第２の基材の上に、（吸水層を第２の基材の側に位置させて）積層されてなる複層形態（二層形態）の吸水性シートと、吸水層の上に第１の基材を積層した積層体が、第２の基材の上に１層のみ積層されてなる単層形態の吸水性シートでは、単層形態の吸水性シートの方が逆戻りの低減効果が大きい。その理由は不明であり、換言すれば、当業者にとっても予期せぬ効果といえる。 On the other hand, it is considered that the water-absorbent sheet of the present invention can buffer the increase in the volume of the region containing the particulate water-absorbent because the first base material has elasticity. That is, when the particulate water absorbing agent swells, the first base material expands in response to the swelling, so that the decrease in the gap can be suppressed, and thus the shape of the gap can be maintained. As a result, even if the liquid is introduced a plurality of times intermittently, the amount of reversion can be reduced without reducing the diffusion ability of the liquid. Further, since the first base material expands and contracts to buffer the swelling of the particulate water absorbing agent, the fixation of the particulate water absorbing agent to the first base material and / or the second base material is not weakened. Specifically, the first base material in contact with the particulate water-absorbing agent extends into a shape that follows the swollen particulate water-absorbing agent due to the swelling of the particulate water-absorbing agent. As a result, the first base material and the particulate water absorbing agent are entangled with each other, and the particulate water absorbing agent is more strongly held between the first base material and the second base material. Therefore, the water-absorbent sheet of the present invention can suppress the movement of the particulate water-absorbent agent from the region containing the particulate water-absorbent agent in the water-absorbent layer, and can maintain the shape of the water-absorbent sheet. , High shape retention. In the embodiment of the present invention, the laminate in which the first base material is laminated on the water absorption layer and the structure in which the intermediate base material is laminated on the water absorption layer are the second base materials. A multi-layered (two-layered) water-absorbing sheet, which is laminated (with the water-absorbing layer located on the side of the second base material), and the first base material are laminated on the water-absorbing layer. In the single-layer water-absorbent sheet in which only one layer is laminated on the second base material, the single-layer water-absorbent sheet has a greater effect of reducing reversion. The reason is unknown, in other words, it can be said to be an unexpected effect for those skilled in the art.
　吸水性シートでは、吸水層における吸水機能は主に吸水剤（粒子状吸水剤）が担うこととなる。特に、吸水層にパルプが存在する従来の吸収性物品と構成が異なる吸水性シートでは、吸水剤の役割が一層重要となる。特に、本発明においては、第１の基材が伸縮性を有するために、吸水層において粒子状吸水剤が含まれる領域との間に設けられた間隙の形状を維持することができ、吸水剤にいったん導入された液が第１の基材の吸液面まで戻りにくい。よって、吸水性シートの形状が維持できる（すなわち、保形性が高い）とともに、「特定戻り量評価」を優れたものとすることができる。ここで、一般条件での逆戻り量を抑制しようと設計された吸水性シートや吸収性物品が、本願の「特定戻り量評価」において必ずしも優れた結果にならないことを付言しておく。また、本発明の一実施形態に係る吸水性シートは、例えば、走ることを覚え始めの、膀胱がまだまだ小さな乳児が昼間等の活動的に動き回っている時間帯に使用する吸収性物品（例えば、オムツ）として好適であるが、無論使用形態がこれに限定されるわけではない。また、本明細書中に記載したメカニズム等が本願の請求の範囲の技術的範囲を限定することはない。 In the water-absorbing sheet, the water-absorbing function in the water-absorbing layer is mainly carried out by the water-absorbing agent (particulate water-absorbing agent). In particular, in a water-absorbent sheet having a structure different from that of a conventional absorbent article in which pulp is present in the water-absorbent layer, the role of the water-absorbing agent becomes even more important. In particular, in the present invention, since the first base material has elasticity, the shape of the gap provided between the water absorbing layer and the region containing the particulate water absorbing agent can be maintained, and the water absorbing agent can be maintained. It is difficult for the liquid once introduced into the first base material to return to the water absorption surface of the first base material. Therefore, the shape of the water-absorbent sheet can be maintained (that is, the shape retention is high), and the "specific return amount evaluation" can be made excellent. Here, it should be added that a water-absorbent sheet or an absorbent article designed to suppress the amount of reversion under general conditions does not always give excellent results in the "specific return amount evaluation" of the present application. Further, the water-absorbent sheet according to the embodiment of the present invention is an absorbent article (for example, an absorbent article used during a time when an infant whose bladder is still small is actively moving around, such as in the daytime, when he / she begins to learn to run. It is suitable as a diaper), but of course the usage pattern is not limited to this. In addition, the mechanisms and the like described herein do not limit the technical scope of the claims of the present application.
　以下、添付した図面を参照しながら、本発明の実施形態を説明する。なお、図面の説明において同一の要素には同一の符号を付し、重複する説明を省略する。また、図面の寸法比率は、説明の都合上誇張されており、実際の比率とは異なる場合がある。 Hereinafter, embodiments of the present invention will be described with reference to the attached drawings. In the description of the drawings, the same elements are designated by the same reference numerals, and duplicate description will be omitted. In addition, the dimensional ratios in the drawings are exaggerated for convenience of explanation and may differ from the actual ratios.
　本発明の第１の実施形態に係る吸水性シートは、吸水層の上に第１の基材を積層した積層体のみが、第２の基材の上に、積層されてなる。すなわち、第１の実施形態においては、吸水層が第１の基材および第２の基材に挟持された構造となっている。第１の実施形態について、図１８に基づいて説明する。 The water-absorbent sheet according to the first embodiment of the present invention is formed by laminating only a laminate in which the first base material is laminated on the water-absorbent layer on the second base material. That is, in the first embodiment, the water absorption layer has a structure sandwiched between the first base material and the second base material. The first embodiment will be described with reference to FIG.
　図１８は、本発明の第１の実施形態に係る吸水性シート１０の、断面を表す模式図である。図１８には、吸水性シート１０の３つの形態（（ａ）～（ｃ））が示されている。図１８（ａ）～（ｃ）において、矢印は、吸収される液が導入される方向を示している。第１の基材１１は、吸水層１２に対して吸収される液（吸液される液）が導入される側に位置する。すなわち、第１の基材は、液体の排出側（例えば紙オムツでは肌側）に配置される。第１の基材１１と第２の基材１３との間に吸水層１２が配置される。すなわち、吸水層１２の上に第１の基材１１を積層した積層体１８が、第２の基材１３上に積層されている。 FIG. 18 is a schematic view showing a cross section of the water-absorbent sheet 10 according to the first embodiment of the present invention. FIG. 18 shows three forms ((a) to (c)) of the water-absorbent sheet 10. In FIGS. 18 (a) to 18 (c), the arrows indicate the direction in which the absorbed liquid is introduced. The first base material 11 is located on the side where the liquid absorbed by the water absorbing layer 12 (the liquid to be absorbed) is introduced. That is, the first base material is arranged on the liquid discharge side (for example, the skin side in the case of paper diapers). The water absorption layer 12 is arranged between the first base material 11 and the second base material 13. That is, the laminate 18 in which the first base material 11 is laminated on the water absorption layer 12 is laminated on the second base material 13.
　図１８（ａ）～（ｃ）において、吸水層１２に粒子状吸水剤１４が含まれる。図１８（ａ）～（ｃ）の形態においては、吸水層１２は、第１の基材１１および第２の基材１３の間に粒子状吸水剤１４が存在している状態を示す。一部の粒子状吸水剤１４は各基材１１，１３から脱離していてもよい。粒子状吸水剤１４（粒子状吸水剤１４が含まれる領域）は、実質的に粒子状吸水剤１４を含まない間隙１５を隔てて配置されている。したがって、吸水「層」とは、シートのような連続体だけを指すのではなく、第１の基材１１および第２の基材１３間に一定の厚さと長さとをもって存在するものであればいずれの形態であってもよい。例えば、吸水層１２は、第１の基材１１と第２の基材１３との間に、一定の厚さと長さとを有して断続的に存在していてもよい。基材１１、及び／又は、１３に粒子状吸水剤１４を固着させる場合、例えば、接着剤を使用すればよい。接着剤を用いて吸水性シートを製造する方法については、〔３．〕にて詳述する。 In FIGS. 18A to 18C, the water absorbing layer 12 contains the particulate water absorbing agent 14. In the form of FIGS. 18A to 18C, the water absorption layer 12 shows a state in which the particulate water absorption agent 14 is present between the first base material 11 and the second base material 13. A part of the particulate water absorbing agent 14 may be detached from each of the base materials 11 and 13. The particulate water-absorbing agent 14 (the region containing the particulate water-absorbing agent 14) is arranged with a gap 15 that does not substantially contain the particulate water-absorbing agent 14. Therefore, the water-absorbing "layer" does not mean only a continuum such as a sheet, but if it exists between the first base material 11 and the second base material 13 with a constant thickness and length. It may be in any form. For example, the water absorption layer 12 may be intermittently present between the first base material 11 and the second base material 13 with a constant thickness and length. When the particulate water absorbing agent 14 is fixed to the base material 11 and / or 13, for example, an adhesive may be used. For the method of producing a water-absorbent sheet using an adhesive, refer to [3. ] Will be described in detail.
　ここで、図１８（ａ）では、間隙１５が、第１の基材１１と第２の基材１３との間に形成されているが、本発明における間隙１５としては、図１８（ｂ）および図１８（ｃ）の形態も含まれる。図１８（ｂ）では、第１の基材１１と第２の基材１３とが接することにより粒子状吸水剤１４が含まれる領域が隔たれている。第１の基材と第２の基材が接触しているが、通液路が維持されているので間隙とみなす。また、吸水層１２に第１の基材１１（場合によっては第１の基材１１と第２の基材１３と）が入り込むことにより、吸水層１２が隔てられるため、当該形態において吸水層１２は断続的に存在する。図１８（ｃ）では、第１の基材１１の端部と第２の基材１３の端部とを重ね合わすことにより、吸水性シート１０の端部が第１の基材１１と第２の基材１３とにより閉じられている。この場合においても、吸水層１２の端部において第１の基材１１（場合によっては第１の基材１１と第２の基材１３と）が入り込むことにより、吸水層１２の端部において、吸水層１２が存在しない状態となる。なお、吸水層１２および間隙１５の形態は、後述の第２の実施形態においても同様に適用される。 Here, in FIG. 18A, the gap 15 is formed between the first base material 11 and the second base material 13, but the gap 15 in the present invention is shown in FIG. 18B. And the form of FIG. 18 (c) is also included. In FIG. 18B, the region containing the particulate water absorbing agent 14 is separated by the contact between the first base material 11 and the second base material 13. Although the first base material and the second base material are in contact with each other, it is regarded as a gap because the liquid passage is maintained. Further, since the water absorption layer 12 is separated by the first base material 11 (in some cases, the first base material 11 and the second base material 13) entering the water absorption layer 12, the water absorption layer 12 in the present embodiment. Exists intermittently. In FIG. 18C, the end portion of the first base material 11 and the end portion of the second base material 13 are overlapped so that the end portion of the water-absorbent sheet 10 becomes the first base material 11 and the second base material 11. It is closed by the base material 13 of the above. Also in this case, the first base material 11 (in some cases, the first base material 11 and the second base material 13) enters at the end portion of the water absorption layer 12, so that the end portion of the water absorption layer 12 The water absorption layer 12 does not exist. The form of the water absorption layer 12 and the gap 15 is similarly applied to the second embodiment described later.
　第１の基材１１内には、粒子状吸水剤１４が存在してもよい。第１の基材１１内の粒子状吸水剤１４としては、例えば、第１の基材１１に接触した（もしくは、固着させた）粒子状吸水剤１４や、第２の基材１３に接触した（もしくは、固着させた）粒子状吸水剤１４が脱離して、第１の基材１１内に捕捉された粒子状吸水剤１４であってもよい。第１の基材１１内に粒子状吸水剤１４が存在する場合、第１の基材１１中の粒子状吸水剤１４の含有割合は、吸水性シート１０全体に含まれる粒子状吸水剤１４に対して、好ましくは５％以上であり、より好ましくは１０％以上であり、さらに好ましくは２０％以上であり、さらにより好ましくは３０％以上である。なお、上限は特に制限されないが、好ましい順に、９０％以下、７０％以下、５０％以下である。なお、本明細書中、吸水性シート１０全体に含まれる粒子状吸水剤１４に対する第１の基材１１中の粒子状吸水剤１４の含有割合は、後述の実施例の方法により算出される。 The particulate water absorbing agent 14 may be present in the first base material 11. The particulate water absorbing agent 14 in the first base material 11 is, for example, in contact with the particulate water absorbing agent 14 that has come into contact with (or has been fixed to) the first base material 11 or the second base material 13. The particulate water-absorbing agent 14 (or fixed) may be desorbed and captured in the first base material 11. When the particulate water absorbing agent 14 is present in the first base material 11, the content ratio of the particulate water absorbing agent 14 in the first base material 11 is the particle water absorbing agent 14 contained in the entire water absorbing sheet 10. On the other hand, it is preferably 5% or more, more preferably 10% or more, still more preferably 20% or more, and even more preferably 30% or more. The upper limit is not particularly limited, but is 90% or less, 70% or less, and 50% or less in the preferred order. In the present specification, the content ratio of the particulate water absorbing agent 14 in the first base material 11 to the particulate water absorbing agent 14 contained in the entire water absorbing sheet 10 is calculated by the method of Examples described later.
　間隙１５の領域に粒子状吸水剤１４を散布、配置しないため、間隙１５の領域は、実質的に粒子状吸水剤１４を含有しない。この間隙１５の領域に粒子状吸水剤１４以外の添加剤等を含有してもよい。例えば、間隙１５は、第１の基材１１と第２の基材１３とが直接または接着剤を介して接することにより形成されていてもよい。第１の基材１１は伸縮性を有するため、第２の基材１３上に粒子状吸水剤１４が含まれる領域が存在する場合、第１の基材１１は粒子状吸水剤１４が含まれる領域に追随して伸縮する。よって、第１の基材１１は、粒子状吸水剤１４が含まれる領域上で粒子状吸水剤１４が含まれる領域を覆うような形状となり、間隙１５上では、粒子状吸水剤１４が含まれる領域の上側面に沿った後、第２の基材１３に向けて沈み込む形状となる。 Since the particulate water absorbing agent 14 is not sprayed or arranged in the region of the gap 15, the region of the gap 15 does not substantially contain the particulate water absorbing agent 14. Additives other than the particulate water absorbing agent 14 may be contained in the region of the gap 15. For example, the gap 15 may be formed by contacting the first base material 11 and the second base material 13 directly or via an adhesive. Since the first base material 11 has elasticity, the first base material 11 contains the particulate water absorbing agent 14 when there is a region on the second base material 13 containing the particulate water absorbing agent 14. It expands and contracts according to the area. Therefore, the first base material 11 has a shape that covers the region containing the particulate water absorbing agent 14 on the region containing the particulate water absorbing agent 14, and contains the particulate water absorbing agent 14 on the gap 15. After being along the upper side surface of the region, the shape is such that it sinks toward the second base material 13.
　本発明の第１の実施形態に係る吸水性シートにおいて、間隙１５における第１の基材１１の吸液面から第２の基材１３の吸水層側の表面までの厚み（Ｌａ）に対する、粒子状吸水剤１４が含まれる領域における第１の基材１１の吸液面から第２の基材の吸水層１２側の表面までの厚み（Ｌｂ）の比（Ｌｂ／Ｌａ）が、１．０５以下であるのが好ましい。第１の基材１１は伸縮性を有するため、第１の基材１１が粒子状吸水剤１４と接する部分において、粒子状吸水剤１４が含まれる領域の形状（すなわち、第１の基材と接する粒子状吸水剤１４において第１の基材１１と接する側の粒子状吸水剤１４の形状）に追随した形状となる（すなわち、追随して伸縮する）。よって、第１の基材１１は粒子状吸水剤１４（粒子状吸水剤１４が含まれる領域）と密着することができ、これにより、第１の基材１１は粒子状吸水剤１４（粒子状吸水剤１４が含まれる領域）と一体化された状態となっている。この場合、Ｌａの厚みとＬｂの厚みとの差が小さく、よって、Ｌｂ／Ｌａが１．０５以下となる。この場合、粒子状吸水剤１４が含まれる領域の形状の保形性が高い。よって、粒子状吸水剤１４が膨潤した後であっても間隙１５の維持性が高く、逆戻りをより低減することができる。なお、Ｌｂ／Ｌａは、通常１以上となる。 In the water-absorbent sheet according to the first embodiment of the present invention, the particles with respect to the thickness (La) from the liquid-absorbing surface of the first base material 11 to the surface of the second base material 13 on the water-absorbing layer side in the gap 15. The ratio (Lb / La) of the thickness (Lb) from the liquid absorbing surface of the first base material 11 to the surface of the second base material on the water absorbing layer 12 side in the region containing the water absorbing agent 14 is 1.05. It is preferably as follows. Since the first base material 11 has elasticity, the shape of the region containing the particulate water absorbing agent 14 (that is, the first base material) in the portion where the first base material 11 is in contact with the particulate water absorbing agent 14 The particle-like water-absorbing agent 14 in contact has a shape that follows (that is, the shape of the particle-like water-absorbing agent 14 on the side in contact with the first base material 11) (that is, expands and contracts accordingly). Therefore, the first base material 11 can be brought into close contact with the particulate water absorbing agent 14 (the region containing the particulate water absorbing agent 14), whereby the first base material 11 can be brought into close contact with the particulate water absorbing agent 14 (particulate). It is in a state of being integrated with the region (region containing the water absorbing agent 14). In this case, the difference between the thickness of La and the thickness of Lb is small, so that Lb / La is 1.05 or less. In this case, the shape retention of the shape of the region containing the particulate water absorbing agent 14 is high. Therefore, even after the particulate water absorbing agent 14 has swelled, the maintainability of the gap 15 is high, and the reversion can be further reduced. Lb / La is usually 1 or more.
　吸水性シート１０において、第２の基材１３上の一部に粒子状吸水剤１４の非存在領域が設けられることにより、間隙１５が形成される。間隙１５（すなわち、粒子状吸水剤１４の非存在領域）は、第１の基材１１の吸液面における一の方向に沿って連続して設けられることにより、通液路としての機能がより発揮できる。間隙１５が連続して設けられる形状としては、例えば、直線状、曲線状、または波型であってもよいが、これらの間隙１５が直線状で並列して設けられるのが好ましい。よって、吸水性シート１０において、粒子状吸水剤１４が含まれる領域および間隙１５は、第１の基材１１の吸液面における一の方向（液が吸液される方向と垂直の面方向）に沿って伸びた形状を有し、並列して配置されているのが好ましい。すなわち、粒子状吸水剤１４が含まれる領域が、筋状（縞状）に並んだ状態とされる。これにより、間隙１５も縞状に形成されるため、粒子状吸水剤１４が膨潤した場合にも間隙１５が維持しやすく、結果として逆戻りをさらに低減できる。ここで、「一の方向」とは、厚み方向を除く、第１の基材１１の吸液面における面方向に平行ないずれかの方向、すなわち、第１の基材１１の吸液面における長手方向、短手方向、またはこれらの方向に対して傾斜した方向のいずれでもよい。間隙１５の役割と、粒子状吸水剤１４の役割とのバランスの観点から、吸水性シート１０において、粒子状吸水剤１４が含まれる領域および間隙１５は、第１の基材１１の吸液面における長手方向に沿って伸びた形状を有し、並列して配置されているのが好ましい。 In the water-absorbent sheet 10, a gap 15 is formed by providing a non-existent region of the particulate water-absorbing agent 14 on a part of the second base material 13. The gap 15 (that is, the non-existent region of the particulate water absorbing agent 14) is continuously provided along one direction on the liquid absorbing surface of the first base material 11, so that the function as a liquid passing path is further enhanced. Can be demonstrated. The shape in which the gaps 15 are continuously provided may be, for example, linear, curved, or corrugated, but it is preferable that the gaps 15 are linearly provided in parallel. Therefore, in the water-absorbent sheet 10, the region and the gap 15 containing the particulate water-absorbing agent 14 are in one direction on the liquid-absorbing surface of the first base material 11 (the plane direction perpendicular to the direction in which the liquid is absorbed). It is preferable that it has a shape extending along the above and is arranged in parallel. That is, the regions containing the particulate water absorbing agent 14 are arranged in a streak (striped) pattern. As a result, the gaps 15 are also formed in stripes, so that the gaps 15 can be easily maintained even when the particulate water absorbing agent 14 swells, and as a result, reversion can be further reduced. Here, the "one direction" is any direction parallel to the surface direction on the liquid absorbing surface of the first base material 11, excluding the thickness direction, that is, on the liquid absorbing surface of the first base material 11. It may be in the longitudinal direction, the lateral direction, or the direction inclined with respect to these directions. From the viewpoint of the balance between the role of the gap 15 and the role of the particulate water absorbing agent 14, in the water absorbing sheet 10, the region containing the particulate water absorbing agent 14 and the gap 15 are the liquid absorbing surfaces of the first base material 11. It is preferable that the particles have a shape extending along the longitudinal direction and are arranged in parallel.
　第１の基材１１の吸水層１２側の面（粒子状吸水剤１４が配置される面）において、粒子状吸水剤１４が含まれる領域の比率（以下、「粒子状吸水剤１４の存在領域の比率」とも称する）は、面積で９０％以下であることが好ましく、８０％以下であることがより好ましく、７５％以下であることがさらにより好ましい。また、第１の基材１１の吸水層１２側の面における粒子状吸水剤１４が含まれる領域の比率は、面積で１０％以上であることが好ましく、２０％以上であることがより好ましい。このような範囲で粒子状吸水剤１４が設けられることで、間隙１５の役割と、粒子状吸水剤１４の役割とのバランスが適当となり、戻り量の低減効果が一層発揮される。なお、第１の基材１１の吸水層１２側の面における粒子状吸水剤１４が含まれる領域の比率は、第２の基材１３の吸水層１２側の面（粒子状吸水剤１４が配置される面）における粒子状吸水剤１４が含まれる領域の比率と同様である。 The ratio of the region containing the particulate water absorbing agent 14 on the surface of the first base material 11 on the water absorbing layer 12 side (the surface on which the particulate water absorbing agent 14 is arranged) (hereinafter, "the region where the particulate water absorbing agent 14 exists"). The ratio (also referred to as "ratio") is preferably 90% or less, more preferably 80% or less, and even more preferably 75% or less in terms of area. Further, the ratio of the region containing the particulate water absorbing agent 14 on the surface of the first base material 11 on the water absorbing layer 12 side is preferably 10% or more, more preferably 20% or more in terms of area. By providing the particulate water absorbing agent 14 in such a range, the role of the gap 15 and the role of the particulate water absorbing agent 14 become appropriate, and the effect of reducing the amount of return is further exhibited. The ratio of the region containing the particulate water absorbing agent 14 on the surface of the first base material 11 on the water absorbing layer 12 side is the surface of the second base material 13 on the water absorbing layer 12 side (the particulate water absorbing agent 14 is arranged). It is the same as the ratio of the region containing the particulate water absorbing agent 14 on the surface).
　ここで、第１の基材１１の吸水層１２側の面における粒子状吸水剤１４が含まれる領域の比率は、吸水性シート１０の製造時に粒子状吸水剤１４の散布領域を調整することにより制御することができる。 Here, the ratio of the region containing the particulate water absorbing agent 14 on the surface of the first base material 11 on the water absorbing layer 12 side is determined by adjusting the spraying region of the particulate water absorbing agent 14 at the time of manufacturing the water absorbing sheet 10. Can be controlled.
　また、例えば、作製した吸水性シート１０を裁断した断面をＸ線ＣＴ装置（ｉｎｓｐｅＸｉｏ　ＳＭＸ－１００ＣＴ）により撮影、解析することにより、第１の基材１１の吸水層１２側の面における粒子状吸水剤１４が含まれる領域の比率を算出することができる。具体的には、吸水性シート１０の断面を撮影し、第１の基材１１または第２の基材１３と吸水層１２との界面を、粒子状吸水剤１４が存在する領域と、粒子状吸水剤１４が存在しない領域とに分類し、それぞれの領域を合計し、その比を算出することにより粒子状吸水剤１４が含まれる領域の比率を算出することができる。なお、吸水性シート１０の短尺方向の断面を３枚以上撮影し、粒子状吸水剤１４が含まれる領域の比率を算出し、それぞれの断面から得られた粒子状吸水剤１４が含まれる領域の比率を平均した値を「粒子状吸水剤１４が含まれる領域の比率」とする。 Further, for example, by photographing and analyzing a cross section of the produced water-absorbent sheet 10 cut with an X-ray CT apparatus (inspeXio SMX-100CT), particulate water absorption on the surface of the first base material 11 on the water-absorbent layer 12 side is performed. The ratio of the region containing the agent 14 can be calculated. Specifically, a cross section of the water-absorbent sheet 10 is photographed, and the interface between the first base material 11 or the second base material 13 and the water-absorbing layer 12 is formed into a region in which the particulate water-absorbing agent 14 is present and a particle-like shape. The ratio of the region containing the particulate water absorbing agent 14 can be calculated by classifying the region into a region in which the water absorbing agent 14 does not exist, summing each region, and calculating the ratio thereof. In addition, three or more cross sections of the water absorbing sheet 10 in the short direction were photographed, the ratio of the region containing the particulate water absorbing agent 14 was calculated, and the region containing the particulate water absorbing agent 14 obtained from each cross section was calculated. The value obtained by averaging the ratios is defined as "the ratio of the region containing the particulate water absorbing agent 14".
　吸水性シート１０に含有される粒子状吸水剤１４の含有量は、好ましくは２００～３６０ｇ／ｍ２であり、より好ましくは２５０～３５０ｇ／ｍ２であり、さらに好ましくは３００～３２５ｇ／ｍ２である。 The content of the particulate water absorbing agent 14 contained in the water absorbing sheet 10 is preferably 200 to 360 g / m 2 , more preferably 250 to 350 g / m 2 , and further preferably 300 to 325 g / m 2. Is.
　吸水性シート１０は、ラッピングシート１６を有する。ラッピングシート１６は、第１の基材１１と第２の基材１３の間で粒子状吸水剤１４が担持された構造物である吸水性シート１０の形状を保持する目的、第１の基材１１と第２の基材１３との間で担持された粒子状吸水剤１４が、吸収体（吸水性シート１０）からこぼれ落ちない（脱落しない）ようにする目的、粒子状吸水剤１４が第１の基材１１を透過し、第１の基材１１の外部表面（液が直接接触する面）に移行した場合、粒子状吸水剤１４が皮膚に直接接触しないようにする目的がある。ラッピングシート１６を有しない場合、例えば、各基材１１，１３同士を接着することで封止（シーリング）する方法、第１の基材１１の表面処理により、第１の基材１１の外部表面への移行を抑制する方法等がある。本願の効果を維持しつつ吸水性シート１０から粒子状吸水剤１４が脱落しない方法として、ラッピングシート１６を有することが好ましい。 The water-absorbent sheet 10 has a wrapping sheet 16. The wrapping sheet 16 is a first base material for the purpose of maintaining the shape of the water absorbing sheet 10, which is a structure in which the particulate water absorbing agent 14 is supported between the first base material 11 and the second base material 13. For the purpose of preventing the particulate water absorbing agent 14 supported between the 11 and the second base material 13 from spilling (not falling off) from the absorber (water absorbing sheet 10), the particulate water absorbing agent 14 is the first. The purpose is to prevent the particulate water absorbent 14 from coming into direct contact with the skin when it permeates through the base material 11 and migrates to the outer surface (the surface with which the liquid comes into direct contact) of the first base material 11. When the wrapping sheet 16 is not provided, for example, by a method of sealing by adhering the base materials 11 and 13 to each other, and by surface treatment of the first base material 11, the outer surface of the first base material 11 is formed. There is a method of suppressing the transition to. It is preferable to have the wrapping sheet 16 as a method of preventing the particulate water absorbing agent 14 from falling off from the water absorbing sheet 10 while maintaining the effect of the present application.
　ラッピングシート１６は、第１の基材１１の上に配置され、吸水層１２と第２の基材１３との全体を包み込むように折り重ねられている。よって、ラッピングシート１６は、第１の基材１１、吸水層１２および第２の基材１３の全体を覆っている。かような構成とすることで、粒子状吸水剤１４の吸水性シート１０からの脱落を抑制することができる。なお、ラッピングシート１６は、第１の基材１１、吸水層１２および第２の基材１３の全体を覆う必要はない。例えば、ラッピングシート１６は、第１の基材１１の上に配置され、吸水層１２の側面と第２の基材１３の側面とを包み込むように折り曲げられ、第２の基材１３の吸液される面（すなわち、吸水層１２が設けられた面）と反対側の面に折り重ねられていてもよい。すなわち、ラッピングシート１６は、第２の基材１３の吸水層１２が設けられた面と反対側の面において、ラッピングシート１６の一端と、ラッピングシート１６の他端とが重なっている。この場合、ラッピングシート１６は、第１の基材１１と、吸水層１２と、第２の基材１３の側面とを覆い、第２の基材１３の吸水層１２が設けられた面と反対側の面の全体または一部を覆っている。例えば、ラッピングシート１６は、第１の基材１１の上に配置され、吸水層１２の側面と第２の基材１３の側面とを包み込むように折り曲げられ、第２の基材１３の吸収される面（すなわち、吸水層１２が設けられた面）と反対側の面において、ラッピングシート１６の一端と、ラッピングシート１６の他端とが離れて配置されていてもよい。この場合、ラッピングシート１６は、第１の基材１１の吸液面と側面と、吸水層１２の側面と、第２の基材１３の側面とを覆い、第２の基材１３の吸水層１２が設けられた面と反対側の面の一部を覆っている。本発明に係る吸水性シートにおいてラッピングシート１６は必須の構成ではないが、本発明に係る吸水性シート１０にラッピングシート１６がかような構成で備えられることにより、粒子状吸水剤１４の吸水性シート１０からの脱落を抑制することができる。 The wrapping sheet 16 is arranged on the first base material 11, and is folded so as to wrap the entire water absorbing layer 12 and the second base material 13. Therefore, the wrapping sheet 16 covers the entire first base material 11, the water absorption layer 12, and the second base material 13. With such a configuration, it is possible to prevent the particulate water absorbing agent 14 from falling off from the water absorbing sheet 10. The wrapping sheet 16 does not need to cover the entire first base material 11, the water absorption layer 12, and the second base material 13. For example, the wrapping sheet 16 is arranged on the first base material 11, bent so as to wrap the side surface of the water absorbing layer 12 and the side surface of the second base material 13, and absorbs the liquid of the second base material 13. It may be folded on the surface opposite to the surface to be formed (that is, the surface provided with the water absorption layer 12). That is, in the wrapping sheet 16, one end of the wrapping sheet 16 and the other end of the wrapping sheet 16 overlap on the surface of the second base material 13 opposite to the surface on which the water absorption layer 12 is provided. In this case, the wrapping sheet 16 covers the first base material 11, the water absorption layer 12, and the side surface of the second base material 13, and is opposite to the surface of the second base material 13 on which the water absorption layer 12 is provided. Covers all or part of the side surface. For example, the wrapping sheet 16 is placed on the first base material 11, bent so as to wrap the side surface of the water absorption layer 12 and the side surface of the second base material 13, and is absorbed by the second base material 13. One end of the wrapping sheet 16 and the other end of the wrapping sheet 16 may be arranged apart from each other on the surface opposite to the surface (that is, the surface provided with the water absorption layer 12). In this case, the wrapping sheet 16 covers the liquid absorbing surface and the side surface of the first base material 11, the side surface of the water absorbing layer 12, and the side surface of the second base material 13, and the water absorbing layer of the second base material 13. It covers a part of the surface opposite to the surface on which the 12 is provided. Although the wrapping sheet 16 is not an essential configuration in the water-absorbent sheet according to the present invention, the water-absorbent sheet 10 according to the present invention is provided with the wrapping sheet 16 in such a configuration so that the water-absorbing agent 14 can absorb water. It is possible to prevent the sheet 10 from falling off.
　よって、本発明の第１の実施形態に係る吸水性シート１０は、少なくとも、第１の基材１１の表面（すなわち、第１の基材１１の吸液面上）に配置させるラッピングシート１６を有することが好ましい。なお、本明細書中、上述のように、ラッピングシート１６を有している場合でも、第１の基材１１が液を直接的に吸収する吸液面を形成するものとするが、例えば、ラッピングシート１６を有する吸水性シート１０においては、ラッピングシート１６が液を直接的に吸収する吸液面を形成するとした場合には、以下のように換言できる；第１の基材と、第２の基材と、前記第１の基材と、前記第２の基材との間に位置する吸水層と、前記第１の基材の表面に配置させるラッピングシートと、を有する、吸水性シートであって、前記吸水層は、粒子状吸水剤を含み、前記粒子状吸水剤が含まれる領域が、実質的に前記粒子状吸水剤を含まない間隙を隔てて配置され、前記ラッピングシートの表面が、液を直接的に吸収する吸液面を形成し、前記第１の基材は、伸び率が１０％以上である。 Therefore, in the water-absorbent sheet 10 according to the first embodiment of the present invention, at least the wrapping sheet 16 to be arranged on the surface of the first base material 11 (that is, on the liquid-absorbing surface of the first base material 11) is placed. It is preferable to have. In the present specification, as described above, even when the wrapping sheet 16 is provided, the first base material 11 forms a water absorbing surface that directly absorbs the liquid. In the water-absorbent sheet 10 having the wrapping sheet 16, if the wrapping sheet 16 forms a liquid-absorbing surface that directly absorbs the liquid, it can be paraphrased as follows; A water-absorbent sheet having a base material, a water-absorbent layer located between the first base material and the second base material, and a wrapping sheet arranged on the surface of the first base material. The water-absorbing layer contains the particulate water-absorbing agent, and the region containing the particulate water-absorbing agent is arranged with a gap substantially free of the particulate water-absorbing agent, and the surface of the wrapping sheet. However, it forms a water-absorbing surface that directly absorbs the liquid, and the first base material has an elongation rate of 10% or more.
　ラッピングシート１６を各基材１１，１３に固着させる方法としては、例えば、接着剤を使用すればよい。 As a method of fixing the wrapping sheet 16 to the base materials 11 and 13, for example, an adhesive may be used.
　本発明の第１の実施形態に係る吸水性シート１０は、第１の基材１１と、吸水層１２における粒子状吸水剤１４とは、直接または接着剤を介して接することが好ましく、および／または、第２の基材１３と、吸水層１２における粒子状吸水剤１４とは、直接または接着剤を介して接することが好ましい。このように、本発明の吸水性シートは、実質的に、第１の基材と；第２の基材と；第１の基材、第２の基材に挟まれている粒子状吸水剤と；粒子状吸水剤を第１の基材および第２の基材の少なくとも一方に固着する接着剤と；必要に応じこれらの一部または全部を包み込むラッピングシートと；のみからなる、シンプルな構成である（粒子状吸水剤に含まれうる本明細書で説明する添加剤等を含むことは排除されない）。より好ましい形態としては、第１の基材と；第２の基材と；第１の基材、第２の基材に挟まれている粒子状吸水剤と；粒子状吸水剤と第２の基材との間で粒子状吸水剤を第２の基材に固着する接着剤と；これらの全部を包み込むラッピングシートと；のみからなる、シンプルな構成である。すなわち、本発明の吸水性シートは、シンプルな構成であるにもかかわらず、特定戻り量が効果的に低減できるものである。 In the water-absorbing sheet 10 according to the first embodiment of the present invention, the first base material 11 and the particulate water-absorbing agent 14 in the water-absorbing layer 12 are preferably in contact with each other directly or via an adhesive, and / Alternatively, it is preferable that the second base material 13 and the particulate water absorbing agent 14 in the water absorbing layer 12 are in contact with each other directly or via an adhesive. As described above, the water-absorbent sheet of the present invention is substantially a particulate water-absorbing agent sandwiched between a first base material, a second base material, and a first base material and a second base material. And; a simple configuration consisting of only an adhesive that adheres the particulate water absorbent to at least one of the first and second substrates; and a wrapping sheet that wraps some or all of these as needed. (It is not excluded that the particulate water-absorbing agent contains the additives and the like described in the present specification). More preferred embodiments include a first substrate; a second substrate; a first substrate, a particulate water absorbent sandwiched between the second substrates; a particulate water absorbent and a second substrate. It has a simple structure consisting only of an adhesive that adheres a particulate water-absorbing agent to the base material to the second base material; and a wrapping sheet that wraps all of them. That is, although the water-absorbent sheet of the present invention has a simple structure, the specific return amount can be effectively reduced.
　本発明の第２の実施形態に係る吸水性シートは、吸水層Ａの上に第１の基材を積層した積層体と、吸水層Ｂの上に中間基材を積層した構成体と、が、（吸水層を第２の基材の側に位置させて）、第２の基材の上に、積層されてなる。以下、第２の実施形態について図１９に基づいて説明するが、第２の実施形態において、第１の実施形態と同様の構成が適用できる要件については省略する。図１９は、本発明の第２の実施形態に係る吸水性シート２０の、断面を表す模式図である。 The water-absorbent sheet according to the second embodiment of the present invention includes a laminate in which the first base material is laminated on the water-absorbent layer A and a structure in which an intermediate base material is laminated on the water-absorbent layer B. , (The water absorption layer is located on the side of the second base material), and is laminated on the second base material. Hereinafter, the second embodiment will be described with reference to FIG. 19, but in the second embodiment, the requirements to which the same configuration as that of the first embodiment can be applied will be omitted. FIG. 19 is a schematic view showing a cross section of the water-absorbent sheet 20 according to the second embodiment of the present invention.
　図１９に示すように、吸水性シート２０は、吸収される液が導入される方向（図１９中、矢印の方向）から順に、第１の基材１１ａと、吸水層１２ａ（吸水層Ａ）と、中間基材１１ｂと、吸水層１２ｂ（吸水層Ｂ）と、が第２の基材１３の上に積層されてなる。すなわち、吸水性シート２０は、第２の基材１３上に、吸水層１２ａの上に第１の基材１１ａを積層した積層体１８ａと、吸水層１２ｂの上に中間基材１１ｂを積層した構成体１８ｂと、が、第２の基材１３の上に、吸水層１２ａ，１２ｂを第２の基材１３の側に位置させて積層されてなる。以下では、積層体１８ａにおける粒子状吸水剤１４を粒子状吸水剤１４ａ、間隙１５を間隙１５ａと称し、構成体１８ｂにおける粒子状吸水剤１４を粒子状吸水剤１４ｂ、間隙１５を間隙１５ｂと称する。なお、第２の実施形態における第１の基材１１ａは、第１の実施形態における第１の基材１１と同様であるため、第１の基材１１として略する場合もある。また、第２の実施形態における粒子状吸水剤１４ａと、間隙１５ａとについても、単に粒子状吸水剤１４と、間隙１５と称する場合がある。 As shown in FIG. 19, the water-absorbing sheet 20 has the first base material 11a and the water-absorbing layer 12a (water-absorbing layer A) in order from the direction in which the liquid to be absorbed is introduced (in the direction of the arrow in FIG. 19). The intermediate base material 11b and the water absorption layer 12b (water absorption layer B) are laminated on the second base material 13. That is, the water-absorbent sheet 20 has a laminated body 18a in which the first base material 11a is laminated on the water-absorbent layer 12a on the second base material 13, and an intermediate base material 11b is laminated on the water-absorbent layer 12b. The structure 18b is laminated on the second base material 13 with the water absorption layers 12a and 12b positioned on the side of the second base material 13. In the following, the particulate water absorbing agent 14 in the laminated body 18a will be referred to as a particulate water absorbing agent 14a, the gap 15 will be referred to as a gap 15a, the particulate water absorbing agent 14 in the structure 18b will be referred to as a particulate water absorbing agent 14b, and the gap 15 will be referred to as a gap 15b. .. Since the first base material 11a in the second embodiment is the same as the first base material 11 in the first embodiment, it may be abbreviated as the first base material 11. Further, the particulate water absorbing agent 14a and the gap 15a in the second embodiment may also be simply referred to as the particulate water absorbing agent 14 and the gap 15.
　吸水層１２ａ，１２ｂは、第１の実施形態と同様に、粒子状吸水剤１４ａ，１４ｂからそれぞれ構成される。具体的には、吸水層１２ａは、第１の基材１１ａに固着している粒子状吸水剤１４ａおよび中間基材１１ｂに固着している粒子状吸水剤１４ａから構成され、吸水層１２ｂは、中間基材１１ｂに固着している粒子状吸水剤１４ｂおよび第２の基材１３に固着している粒子状吸水剤１４ｂから構成される。吸水層１２ａ，１２ｂにおいて、粒子状吸水剤１４ａ，１４ｂが含まれる領域は、それぞれ間隙１５ａ，１５ｂにより隔てられて配置されている。 The water absorbing layers 12a and 12b are composed of the particulate water absorbing agents 14a and 14b, respectively, as in the first embodiment. Specifically, the water absorbing layer 12a is composed of a particulate water absorbing agent 14a fixed to the first base material 11a and a particulate water absorbing agent 14a fixed to the intermediate base material 11b, and the water absorbing layer 12b is composed of a particulate water absorbing agent 14a. It is composed of a particulate water absorbing agent 14b fixed to the intermediate base material 11b and a particulate water absorbing agent 14b fixed to the second base material 13. In the water absorbing layers 12a and 12b, the regions containing the particulate water absorbing agents 14a and 14b are arranged so as to be separated by gaps 15a and 15b, respectively.
　吸水性シート２０において、中間基材１１ｂ上および第２の基材１３上の一部に設けられる間隙１５ａ，１５ｂ（粒子状吸水剤１４の非存在領域）は、第１の実施形態に係る吸水性シート１０と同様の形態であるのが好ましい。すなわち、粒子状吸水剤１４ａ，１４ｂが含まれる領域および間隙１５ａ，１５ｂは、第１の基材の吸液面における一の方向に沿って伸びた形状を有し、並列して配置されているのが好ましい。 In the water-absorbent sheet 20, the gaps 15a and 15b (regions in which the particulate water-absorbing agent 14 does not exist) provided on the intermediate base material 11b and a part on the second base material 13 are water-absorbent according to the first embodiment. It is preferably in the same form as the sex sheet 10. That is, the regions containing the particulate water absorbing agents 14a and 14b and the gaps 15a and 15b have a shape extending along one direction on the liquid absorbing surface of the first base material and are arranged in parallel. Is preferable.
　なお、図１９では、積層体１８ａにおける粒子状吸水剤１４ａが含まれる領域と、構成体１８ｂにおける粒子状吸水剤１４ｂが含まれる領域とが、第１の基材１１ａの面方向において重なるように（すなわち、第１の基材１１ａの吸液面に対する垂直方向において同じ位置に）、同じ厚みと幅とで配置されているが、この位置関係、厚みおよび幅の関係はこれに制限されない。例えば、積層体１８ａにおける粒子状吸水剤１４ａが含まれる領域と、構成体１８ｂにおける粒子状吸水剤１４ｂが含まれる領域とが、面方向において重ならないようにずらして配置してもよい。また、積層体１８ａにおける粒子状吸水剤１４ａが含まれる領域が、構成体１８ｂにおける粒子状吸水剤１４ｂが含まれる領域に比較して、幅広または幅狭にしたり、厚くまたは薄くしてもよい。 In FIG. 19, the region of the laminated body 18a containing the particulate water absorbing agent 14a and the region of the constituent 18b containing the particulate water absorbing agent 14b are overlapped with each other in the plane direction of the first base material 11a. Although they are arranged at the same position (that is, at the same position in the direction perpendicular to the liquid absorption surface of the first base material 11a) with the same thickness and width, the positional relationship, the thickness, and the width relationship are not limited thereto. For example, the region of the laminated body 18a containing the particulate water absorbing agent 14a and the region of the constituent 18b containing the particulate water absorbing agent 14b may be arranged so as not to overlap in the plane direction. Further, the region of the laminated body 18a containing the particulate water-absorbing agent 14a may be wider or narrower, or thicker or thinner than the region of the structure 18b containing the particulate water-absorbing agent 14b.
　第１の基材１１ａ、中間基材１１ｂ内には、粒子状吸水剤１４ａ，１４ｂが存在してもよい。例えば、第１の基材１１ａには、粒子状吸水剤１４ａが存在しうるが、中間基材１１ｂにおいては、中間基材１１ｂの吸液面側の面には粒子状吸水剤１４ａが、中間基材１１ｂの第２の基材１３側の面には粒子状吸水剤１４ｂが存在しうる。 Particley water absorbents 14a and 14b may be present in the first base material 11a and the intermediate base material 11b. For example, the first base material 11a may contain the particulate water absorbing agent 14a, but in the intermediate base material 11b, the particulate water absorbing agent 14a is intermediate on the surface of the intermediate base material 11b on the liquid absorbing surface side. The particulate water absorbing agent 14b may be present on the surface of the base material 11b on the side of the second base material 13.
　本発明の第２の実施形態に係る吸水性シート２０においては、下記の要件について、第１の実施形態の第の１基材１１、吸水層１２、粒子状吸水剤１４、間隙１５が、液が導入される側に配置される積層体１８ａの第１の基材１１ａ、吸水層１２ｂ、粒子状吸水剤１４ａ、間隙１５ａにそれぞれ読み替えられる；
（１）第１の基材１１中の粒子状吸水剤１４の含有割合
（２）間隙１５における第１の基材１１の吸液面から第２の基材１３の吸水層１２側の表面までの厚み（Ｌａ）に対する、粒子状吸水剤１４が含まれる領域における第１の基材１１の吸液面から第２の基材１３の吸水層１２側の表面までの厚み（Ｌｂ）の比（Ｌｂ／Ｌａ）。 In the water-absorbent sheet 20 according to the second embodiment of the present invention, regarding the following requirements, the first base material 11, the water-absorbent layer 12, the particulate water-absorbent agent 14, and the gap 15 of the first embodiment are liquid. Is read as the first base material 11a, the water absorption layer 12b, the particulate water absorption agent 14a, and the gap 15a of the laminate 18a arranged on the side where is introduced;
(1) Content ratio of particulate water absorbing agent 14 in the first base material 11 (2) From the liquid absorbing surface of the first base material 11 to the surface of the second base material 13 on the water absorbing layer 12 side in the gap 15. The ratio of the thickness (Lb) from the liquid absorbing surface of the first base material 11 to the surface of the second base material 13 on the water absorbing layer 12 side in the region containing the particulate water absorbing agent 14 (La). Lb / La).
　なお、二層形態の（２）において、積層体１８ａと構成体１８ｂとの粒子状吸水剤１４ａ，１４ｂが含まれる領域と、間隙１５ａ，１５ｂとが、第１の基材１１ａの面方向において重ならずに形成されている場合がある。この場合、Ｌａの基準となる「間隙１５における」の間隙１５とは、第１の基材１１ａの吸液面に近い（すなわち、積層体１１ａにおける）間隙１５ａであり、Ｌｂの基準となる「粒子状吸水剤１４が含まれる領域における」の粒子状吸水剤１４が含まれる領域とは、第１の基材１１ａの吸液面に近い（すなわち、積層体１１ａにおける）粒子状吸水剤１４ａが含まれる領域である。 In addition, in the two-layer form (2), the region containing the particulate water absorbing agents 14a and 14b of the laminated body 18a and the constituent body 18b and the gaps 15a and 15b are in the plane direction of the first base material 11a. It may be formed without overlapping. In this case, the gap 15 of "in the gap 15" which is the reference of La is the gap 15a close to the liquid absorbing surface of the first base material 11a (that is, in the laminated body 11a), and is the reference of Lb. The region containing the particulate water absorbing agent 14 in the region containing the particulate water absorbing agent 14 is the region where the particulate water absorbing agent 14a close to the liquid absorbing surface of the first base material 11a (that is, in the laminated body 11a) is used. This is the area that is included.
　すなわち、本発明の第２の実施形態に係る吸水性シート２０において、第１の基材１１ａ内に粒子状吸水剤１４が存在する場合、第１の基材１１ａ中の粒子状吸水剤１４の含有割合は、吸水性シート２０全体に含まれる粒子状吸水剤１４に対して、好ましくは５％以上であるのが好ましい。 That is, in the water-absorbing sheet 20 according to the second embodiment of the present invention, when the particulate water-absorbing agent 14 is present in the first base material 11a, the particulate water-absorbing agent 14 in the first base material 11a The content ratio is preferably 5% or more with respect to the particulate water absorbing agent 14 contained in the entire water absorbing sheet 20.
　また、本発明の第２の実施形態に係る吸水性シート２０において、間隙１５ａにおける第１の基材１１ａの吸液面から第２の基材１３の吸水層１２ｂ側の表面までの厚み（Ｌａ）に対する、粒子状吸水剤１４ａが含まれる領域における第１の基材１１ａの吸液面から第２の基材１３の吸水層１２ｂ側の表面までの厚み（Ｌｂ）の比（Ｌｂ／Ｌａ）が、１．０５以下であるであるのが好ましい。吸水性シート２０において、第１の基材１１ａ中の粒子状吸水剤１４ａの含有割合およびＬｂ／Ｌａは、第１の実施形態に係る吸水性シート１０の好ましい範囲が同様に適用できる。 Further, in the water-absorbent sheet 20 according to the second embodiment of the present invention, the thickness (La) from the liquid-absorbing surface of the first base material 11a in the gap 15a to the surface of the second base material 13 on the water-absorbing layer 12b side. ) To the ratio (Lb / La) of the thickness (Lb) from the liquid absorbing surface of the first base material 11a to the surface of the second base material 13 on the water absorbing layer 12b side in the region containing the particulate water absorbing agent 14a. However, it is preferably 1.05 or less. In the water-absorbent sheet 20, the content ratio of the particulate water-absorbent 14a in the first base material 11a and Lb / La can be similarly applied to the preferable range of the water-absorbent sheet 10 according to the first embodiment.
　吸水性シート２０は、ラッピングシート１６を有する。ラッピングシート１６は、第１の基材１１ａの上に配置され、積層体１８ａと構成体１８ｂと第２の基材１３との全体を包み込むように折り重ねられている。よって、本発明の第２の実施形態に係る吸水性シート２０は、少なくとも、第１の基材１１ａの表面（すなわち、第１の基材の吸液面）に配置させるラッピングシート１６を有することが好ましい。 The water-absorbent sheet 20 has a wrapping sheet 16. The wrapping sheet 16 is arranged on the first base material 11a, and is folded so as to wrap the entire laminated body 18a, the constituent body 18b, and the second base material 13. Therefore, the water-absorbent sheet 20 according to the second embodiment of the present invention has at least a wrapping sheet 16 to be arranged on the surface of the first base material 11a (that is, the liquid-absorbent surface of the first base material). Is preferable.
　なお、本明細書中、以下のように換言できる；第１の基材と、中間基材と、第２の基材と、吸水層と、ラッピングシートと、を有する、吸水性シートであって、前記吸水層の上に前記第１の基材を積層した積層体と、前記吸水層の上に前記中間基材を積層した構成体とが、第２の基材の上に、前記吸水層を前記第２の基材の側に位置させて積層されており、前記ラッピングシートは、前記第１の基材の表面に配置され、前記吸水層は、粒子状吸水剤を含み、前記粒子状吸水剤が含まれる領域が、実質的に前記粒子状吸水剤を含まない間隙を隔てて配置され、前記ラッピングシートの表面が、液を直接的に吸収する吸液面を形成し、前記第１の基材は、伸び率が１０％以上である。 In the present specification, it can be paraphrased as follows; a water-absorbent sheet having a first base material, an intermediate base material, a second base material, a water-absorbent layer, and a wrapping sheet. A laminate in which the first base material is laminated on the water absorption layer and a structure in which the intermediate base material is laminated on the water absorption layer are formed on the second base material. Is laminated on the side of the second base material, the wrapping sheet is arranged on the surface of the first base material, and the water absorbing layer contains a particulate water absorbing agent and is in the form of particles. The region containing the water absorbing agent is arranged with a gap substantially free of the particulate water absorbing agent, and the surface of the wrapping sheet forms a liquid absorbing surface that directly absorbs the liquid, and the first The base material of No. 1 has an elongation rate of 10% or more.
　本発明の第２の実施形態に係る吸水性シート２０は、第１の基材１１ａと、吸水層１２ａにおける粒子状吸水剤１４ａとは、直接または接着剤を介して接することが好ましく、中間基材１１ｂと、吸水層１２ａにおける粒子状吸水剤１４ａとは、直接または接着剤を介して接することが好ましく、中間基材１１ｂと、吸水層１２ｂにおける粒子状吸水剤１４ｂとは、直接または接着剤を介して接することが好ましく、および／または、第２の基材１３と、吸水層１２ｂにおける粒子状吸水剤１４ｂとは、直接または接着剤を介して接することが好ましい。 In the water-absorbing sheet 20 according to the second embodiment of the present invention, the first base material 11a and the particulate water-absorbing agent 14a in the water-absorbing layer 12a are preferably in contact with each other directly or via an adhesive, and an intermediate group is used. The material 11b and the particulate water absorbing agent 14a in the water absorbing layer 12a are preferably in contact with each other directly or via an adhesive, and the intermediate base material 11b and the particulate water absorbing agent 14b in the water absorbing layer 12b are directly or adhesive. The second base material 13 and the particulate water absorbing agent 14b in the water absorbing layer 12b are preferably brought into contact with each other directly or via an adhesive.
　第２の実施形態に係る吸水性シート２０において、第１の基材１１ａの吸水層１２ａ側の面（粒子状吸水剤１４ａが配置される面）における粒子状吸水剤１４ａが含まれる領域の比率、および中間基材１１ｂの吸水層１２ｂ側（粒子状吸水剤１４ｂが配置される面）における粒子状吸水剤１４ｂが含まれる領域の比率は、面積で９０％以下であることが好ましく、８０％以下であることがより好ましく、７５％以下であることがさらにより好ましい。また、第１の基材１１ａの吸水層１２ａ側の面における粒子状吸水剤１４ａが含まれる領域の比率、および中間基材１１ｂの吸水層１２ｂ側における粒子状吸水剤１４ｂが含まれる領域の比率は、面積で１０％以上であることが好ましく、２０％以上であることがより好ましい。このような範囲で粒子状吸水剤１４ａ，１４ｂが設けられることで、間隙１５ａ，１５ｂの役割と、粒子状吸水剤１４ａ，１４ｂの役割とのバランスが適当となり、戻り量の低減効果が一層発揮される。なお、第１の基材１１ａの吸水層１２ａ側の面における粒子状吸水剤１４ａが含まれる領域の比率は、中間基材１１ｂの吸水層１２ａ側の面（粒子状吸水剤１４ａが配置される面）における粒子状吸水剤１４ａが含まれる領域の比率と同様であり、中間基材１１ｂの吸水層１２ｂにおける粒子状吸水剤１４ｂが含まれる領域の比率は、第２の基材１３の吸水層１２ｂ（粒子状吸水剤１４ｂが配置される面）における粒子状吸水剤１４ｂが含まれる領域の比率と同様である。 In the water-absorbing sheet 20 according to the second embodiment, the ratio of the area containing the particulate water-absorbing agent 14a on the surface of the first base material 11a on the water-absorbing layer 12a side (the surface on which the particulate water-absorbing agent 14a is arranged). , And the ratio of the region containing the particulate water absorbing agent 14b on the water absorbing layer 12b side (the surface on which the particulate water absorbing agent 14b is arranged) of the intermediate base material 11b is preferably 90% or less in terms of area, preferably 80%. It is more preferably less than or equal to, and even more preferably 75% or less. Further, the ratio of the region containing the particulate water absorbing agent 14a on the surface of the first base material 11a on the water absorbing layer 12a side and the ratio of the region containing the particulate water absorbing agent 14b on the water absorbing layer 12b side of the intermediate base material 11b. Is preferably 10% or more in area, and more preferably 20% or more. By providing the particulate water absorbents 14a and 14b in such a range, the balance between the roles of the gaps 15a and 15b and the roles of the particulate water absorbents 14a and 14b becomes appropriate, and the effect of reducing the amount of return is further exhibited. Will be done. The ratio of the region containing the particulate water absorbing agent 14a on the surface of the first base material 11a on the water absorbing layer 12a side is such that the surface of the intermediate base material 11b on the water absorbing layer 12a side (the particulate water absorbing agent 14a is arranged). The ratio of the region containing the particulate water absorbing agent 14a in the surface) is the same as the ratio of the region containing the particulate water absorbing agent 14b in the water absorbing layer 12b of the intermediate base material 11b, and the ratio of the region containing the particulate water absorbing agent 14b is the water absorbing layer of the second base material 13. It is the same as the ratio of the region containing the particulate water absorbing agent 14b in 12b (the surface on which the particulate water absorbing agent 14b is arranged).
　なお、吸水性シート２０において、第１の基材１１または第２の基材１３における粒子状吸水剤１４ａ，１４ｂの存在領域の比率は、吸水性シート１０と同様にして算出することができる。 In the water-absorbent sheet 20, the ratio of the regions where the particulate water- absorbents 14a and 14b are present in the first base material 11 or the second base material 13 can be calculated in the same manner as in the water-absorbent sheet 10.
　ここで、吸水性シート２０に含有される粒子状吸水剤１４の含有量は、好ましくは２００～３６０ｇ／ｍ２であり、より好ましくは２１０～３５０ｇ／ｍ２であり、さらに好ましくは２２５～３２５ｇ／ｍ２である。吸水性シート２０においては、吸水層１２ａ，１２ｂに存在する粒子状吸水剤１４ａ,１２ｂの合計が上記範囲となるように調整すればよく、好ましくは、吸水層１２ａ，１２ｂに存在する粒子状吸水剤１４ａ,１２ｂの量が、２：１～１：２であるのが好ましく、１．５：１～１：１．５であるのがより好ましい。 Here, the content of the particulate water absorbing agent 14 contained in the water absorbing sheet 20 is preferably 200 to 360 g / m 2 , more preferably 210 to 350 g / m 2 , and further preferably 225 to 325 g. / M 2 . In the water-absorbing sheet 20, the total amount of the particulate water-absorbing agents 14a and 12b existing in the water-absorbing layers 12a and 12b may be adjusted to be within the above range, and preferably, the particulate water-absorbing agents existing in the water-absorbing layers 12a and 12b may be adjusted. The amounts of the agents 14a and 12b are preferably 2: 1 to 1: 2, and more preferably 1.5: 1 to 1: 1.5.
　本発明の第１および第２の実施形態に係る吸水性シート１０，２０において、一実施形態によれば、第１の基材１１が嵩高い形態（低い嵩密度で有意に厚い形態）となりうるが、従来型の吸収性物品に用いられる吸収体よりも、薄型化が可能である。上記吸水性シート１０，２０を、紙オムツに使用する場合、その厚さは、例えば４０％ＲＨ～５０％ＲＨにおいて、好ましくは１５ｍｍ以下、より好ましくは１０ｍｍ以下、さらにより好ましくは７ｍｍ以下、特に好ましくは５ｍｍ以下、最も好ましくは４ｍｍ以下である。一方、厚さの下限は、吸水性シート１０，２０の強度および粒子状吸水剤１４の直径を鑑みると、好ましくは０．２ｍｍ以上、より好ましくは０．３ｍｍ以上、よりさらに好ましくは０．５ｍｍ以上である。本願の実施例で使用した吸水性シート１０，２０の厚みは、２～５ｍｍであった。 In the water- absorbent sheets 10 and 20 according to the first and second embodiments of the present invention, according to one embodiment, the first base material 11 can be in a bulky form (a form having a low bulk density and a significantly thick form). However, it can be made thinner than the absorber used in the conventional absorbent article. When the water- absorbent sheets 10 and 20 are used for disposable diapers, the thickness thereof is, for example, 40% RH to 50% RH, preferably 15 mm or less, more preferably 10 mm or less, still more preferably 7 mm or less, particularly. It is preferably 5 mm or less, and most preferably 4 mm or less. On the other hand, the lower limit of the thickness is preferably 0.2 mm or more, more preferably 0.3 mm or more, still more preferably 0.5 mm in consideration of the strength of the water absorbing sheets 10 and 20 and the diameter of the particulate water absorbing agent 14. That is all. The thickness of the water- absorbent sheets 10 and 20 used in the examples of the present application was 2 to 5 mm.
　なお、本願における第１の基材１１、中間基材１１ｂ、第２の基材１３、ラッピングシート１６、吸水性シート１０，２０の厚みは、ダイヤルシックネスゲージ　大型タイプ（厚み測定器）（株式会社　尾崎製作所製、型番：Ｊ－Ｂ、測定子：アンビル上下φ５０ｍｍ）を用いて測定した。測定点数は、測定対象のシートにおいて、異なる箇所を５点とし、各箇所について２回測定し、測定値は合計５点の平均値とした。厚み測定時は、測定対象のシートに圧力が出来るだけかからないよう、ハンドルからゆっくりと手を離し、厚みを測定した。具体的な手順としては、測定対象のシートの測定箇所に皺や歪みが生じないよう、厚みが一定の板の上に平らに貼り付け、その板を厚み測定器の下部測定子の上にセットする。次に、厚み測定器の上部測定子を測定対象のシートから２～３ｍｍの高さ位置まで近づけた後、ハンドルからゆっくりと手を離し、測定対象のシートと板を合わせた厚みを測定する。測定対象のシートの厚みは、式：Ｔ１＝Ｔ２－Ｔ０（Ｔ０：板の厚み（ｍｍ）、Ｔ１：測定対象のシートの厚み（ｍｍ）、Ｔ２：測定対象のシートおよび板の厚み（ｍｍ））によって定まる。 The thickness of the first base material 11, the intermediate base material 11b, the second base material 13, the lapping sheet 16, and the water absorbing sheets 10 and 20 in the present application is a dial thickness gauge large type (thickness measuring instrument) (Co., Ltd.). Measurement was performed using a manufacturer of Ozaki Seisakusho, model number: JB, stylus: anvil top and bottom φ50 mm). The number of measurement points was 5 points at different points on the sheet to be measured, and the measurement was performed twice at each point, and the measured values were the average value of a total of 5 points. When measuring the thickness, the thickness was measured by slowly releasing the hand from the handle so that pressure was not applied to the sheet to be measured as much as possible. As a specific procedure, the sheet to be measured is pasted flat on a plate having a constant thickness so that wrinkles and distortion do not occur at the measurement location, and the plate is set on the lower stylus of the thickness measuring instrument. To do. Next, after bringing the upper stylus of the thickness measuring instrument close to a height position of 2 to 3 mm from the sheet to be measured, slowly release the hand from the handle to measure the combined thickness of the sheet and the plate to be measured. The thickness of the sheet to be measured is the formula: T1 = T2-T0 (T0: thickness of the plate (mm), T1: thickness of the sheet to be measured (mm), T2: thickness of the sheet to be measured and the plate (mm)). ).
　吸水性シート１０，２０にさらに通液性、拡散性、柔軟性などを付与するために、吸水性シート１０，２０の表面（第１の基材１１の液を直接的に吸収する吸液面またはラッピングシート１６の表面）に適宜エンボス加工を施してもよい。エンボス加工を施す領域は、吸水性シート１０，２０表面の全面でもよく、一部でもよい。連続したエンボス加工領域を、吸水性シート１０，２０の長手方向に設けることにより、液を長手方向に容易に拡散させることができる。吸水性シート１０，２０においては、吸水層１２において、粒子状吸水剤１４が存在しない間隙１５を有している。このように、間隙１５に加えて、エンボス加工領域を、長手方向に連続して設けることにより、当該領域が、大量の液を流すための通液路（液体搬送通路）の役割を果たす。エンボス加工領域は直線状に設けても、曲線状に設けても、波型に設けてもよい。 The surface of the water-absorbent sheets 10 and 20 (the liquid-absorbing surface that directly absorbs the liquid of the first base material 11) in order to further impart liquid permeability, diffusivity, flexibility, etc. to the water- absorbent sheets 10 and 20. Alternatively, the surface of the wrapping sheet 16) may be appropriately embossed. The region to be embossed may be the entire surface of the water- absorbent sheets 10 and 20 or a part thereof. By providing a continuous embossed region in the longitudinal direction of the water- absorbent sheets 10 and 20, the liquid can be easily diffused in the longitudinal direction. In the water-absorbing sheets 10 and 20, the water-absorbing layer 12 has a gap 15 in which the particulate water-absorbing agent 14 does not exist. In this way, by providing the embossed region continuously in the longitudinal direction in addition to the gap 15, the region serves as a liquid passage (liquid transport passage) for flowing a large amount of liquid. The embossed region may be provided linearly, curvedly, or corrugated.
　本発明は、上述した実施形態に限定されるものではなく、特許請求の範囲内で種々改変することができる。 The present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the claims.
　以下、吸水性シートを構成する各部材について詳細に説明する。 Hereinafter, each member constituting the water-absorbent sheet will be described in detail.
　［２－１．第１の基材］
　第１の基材は、吸液される液が導入される側に位置する、透水性シートである。なお、吸液される液とは水に限らず、尿、血液、汗、糞、廃液、湿気、蒸気、氷、水と有機溶媒および／または無機溶媒との混合物、雨水、地下水等であってもよく、水を含んでいれば特に制限されるものではない。好ましくは、尿、経血、汗、その他の体液を挙げることができる。 [2-1. First base material]
The first base material is a water-permeable sheet located on the side where the liquid to be absorbed is introduced. The liquid to be absorbed is not limited to water, but urine, blood, sweat, feces, waste liquid, moisture, vapor, ice, a mixture of water and an organic solvent and / or an inorganic solvent, rainwater, groundwater, etc. However, it is not particularly limited as long as it contains water. Preferably, urine, menstrual blood, sweat and other body fluids can be mentioned.
　第１の基材が、透水性シートであり、かつ、吸液される側に位置することで、本発明の効果である吸水性シートの性能（逆戻り量、面方向の漏れなど）を充分に発揮することができる。透水性シートにおける透水性は、透水係数（ＪＩＳ　Ａ１２１８：２００９）が１×１０－５ｃｍ／ｓｅｃ以上であることが好ましい。該透水係数は、より好ましくは１×１０－４ｃｍ／ｓｅｃ以上、さらにより好ましくは１×１０－３ｃｍ／ｓｅｃ以上、特に好ましくは１×１０－２ｃｍ／ｓｅｃ以上、最も好ましくは１×１０－１ｃｍ／ｓｅｃ以上である。本願の実施例で使用した第１の基材の透水係数は、１×１０－５ｃｍ／ｓｅｃ以上であった。 Since the first base material is a water-permeable sheet and is located on the side where the liquid is absorbed, the performance of the water-absorbent sheet (return amount, leakage in the plane direction, etc.), which is the effect of the present invention, can be sufficiently improved. Can be demonstrated. The water permeability of the water-permeable sheet preferably has a water permeability coefficient (JIS A1218: 2009) of 1 × 10-5 cm / sec or more. The hydraulic conductivity is more preferably 1 × 10 -4 cm / sec or more, even more preferably 1 × 10 -3 cm / sec or more, particularly preferably 1 × 10 −2 cm / sec or more, and most preferably 1 × It is 10 -1 cm / sec or more. The hydraulic conductivity of the first substrate used in the examples of the present application was 1 × 10-5 cm / sec or more.
　本発明において、第１の基材の伸び率は、１０％以上であり、好ましくは１５％以上であり、より好ましくは１７％で以上であり、さらに好ましくは２０％以上であり、さらにより好ましくは２２％以上である。第１の基材の伸び率の上限は、特に制限されないが、６０％以下であるのが好ましい。第１の基材の伸び率がかような範囲であることにより、第１の基材が粒子状吸水剤の形状に追随しやすくなり、結果として吸水性シートの保形性がさらに高まり、逆戻り量をさらに低減できる。第１の基材の伸び率は、後述の実施例に記載の方法で測定された値を採用する。本明細書中、「不織布（第１の基材）の伸び率」としては、最も伸張する方向で伸び率を測定した際の数値とする。また、第１の基材の伸び率は、嵩密度、目付量、材質、網目構造、製造工程条件などによって制御可能である。 In the present invention, the elongation rate of the first base material is 10% or more, preferably 15% or more, more preferably 17% or more, still more preferably 20% or more, still more preferably. Is 22% or more. The upper limit of the elongation rate of the first base material is not particularly limited, but is preferably 60% or less. When the elongation rate of the first base material is within such a range, the first base material can easily follow the shape of the particulate water absorbing agent, and as a result, the shape retention of the water absorbing sheet is further enhanced, and the water absorbing sheet reverts. The amount can be further reduced. As the elongation rate of the first base material, a value measured by the method described in Examples described later is adopted. In the present specification, the "elongation rate of the non-woven fabric (first base material)" is a numerical value when the elongation rate is measured in the direction of maximum elongation. Further, the elongation rate of the first base material can be controlled by the bulk density, the basis weight, the material, the mesh structure, the manufacturing process conditions, and the like.
　なお、本発明において、第１の基材の伸びる方向は、厚み方向を除く、第１の基材の面方向に平行ないずれかの一方向が伸びればよく、特に制限されない。例えば、長方形の吸水性シートであれば、シート平面の長辺方向、短辺方向、対角線方向など、あらゆる角度の方向からいずれか一方向が、上記範囲の伸び率で伸びればよい。正方形、楕円形、円形の吸水性シートであった場合でも同様である。好ましくは、あらゆる方向（等方的）から伸びることができる基材である。 In the present invention, the extending direction of the first base material is not particularly limited as long as it extends in any one direction parallel to the surface direction of the first base material, excluding the thickness direction. For example, in the case of a rectangular water-absorbent sheet, any one direction from any angle direction such as the long side direction, the short side direction, and the diagonal direction of the sheet plane may be stretched at the elongation rate in the above range. The same applies to the case of a square, oval, or circular water-absorbent sheet. Preferably, it is a substrate that can extend from all directions (isotropic).
　本発明において、第１の基材は、目付量が３～８０ｇ／ｍ２であるのが好ましく、５～７０ｇ／ｍ２であるのがより好ましく１０～６０ｇ／ｍ２であるのがさらに好ましい。第１の基材の目付量がかような範囲であることにより、第１の基材中に粒子状吸水剤を取り込みやすくなり、結果として吸水性シートの保形性がさらに高まり、逆戻り量をさらに低減できる。 In the present invention, the first base material preferably has a basis weight of 3 to 80 g / m 2 , more preferably 5 to 70 g / m 2 , and even more preferably 10 to 60 g / m 2. .. When the basis weight of the first base material is within such a range, it becomes easy to take in the particulate water-absorbing agent into the first base material, and as a result, the shape-retaining property of the water-absorbent sheet is further enhanced, and the amount of reversion is increased. It can be further reduced.
　本発明において、第１の基材は、嵩密度が０．１ｇ／ｃｍ３以下であるのが好ましく、０．０８ｇ／ｃｍ３以下であるのがより好ましく、０．０５ｇ／ｃｍ３以下であるのがさらに好ましい。第１の基材の嵩密度は、好ましくは０．００１ｇ／ｃｍ３以上であり、より好ましくは０．００５ｇ／ｃｍ３以上であり、さらに好ましくは０．０１ｇ／ｃｍ３以上である。本明細書中、嵩密度とは、単位体積に対する質量であり、基材を高圧圧縮した場合（空隙を無くした場合）における密度ではなく、空隙の体積も含めた基材の体積より求めた密度である。第１の基材の嵩密度が０．１ｇ／ｃｍ３以下であるとは、第１の基材が軽いことを意味する。嵩高いとは、低い嵩密度で有意に厚いことを意味する。本発明では、第１の基材が嵩高いことにより、第１の基材中に粒子状吸水剤を取り込みやすくなり、結果として吸水性シートの保形性がさらに高まり、逆戻り量をさらに低減できる。また、本発明においては、第１の基材が嵩高いことにより、下記の効果も期待できる。すなわち、第１の基材が嵩高いため、第１の基材の吸液面に接した吸収される液が、速やかに下層である吸水層および第２の基材へと流れ込み、第１の基材の吸液面に留まる液が低減できる。さらに、吸収された液が吸水層に到達する際には、液は面方向に拡散されており、ゆえに、液が多量に吸水層に導入されても、吸水層は局所でなく面方向に広がった液を吸収することになる。すなわち、嵩高い第１の基材は、吸水力が低く、通液力が高く、液拡散性が高い。これにより、吸水性シートにおける逆戻り量を低減することができる。第１の基材の吸液面の湿度が抑制でき、肌への不快感が低減できる。第１の基材の嵩密度は、好ましくは０．１ｇ／ｃｍ３以下である。なお、本明細書中、嵩密度は、後述の実施例で算出される値である。 In the present invention, the first substrate has a bulk density is preferably at 0.1 g / cm 3 or less, more preferably at 0.08 g / cm 3 or less, is 0.05 g / cm 3 or less Is even more preferable. The bulk density of the first substrate preferably being 0.001 g / cm 3 or more, more preferably 0.005 g / cm 3 or more, further preferably 0.01 g / cm 3 or more. In the present specification, the bulk density is the mass with respect to the unit volume, and is not the density when the base material is compressed under high pressure (when the voids are eliminated), but the density obtained from the volume of the base material including the volume of the voids. Is. When the bulk density of the first base material is 0.1 g / cm 3 or less, it means that the first base material is light. Bulky means low bulk density and significantly thicker. In the present invention, since the first base material is bulky, it becomes easy to incorporate the particulate water absorbing agent into the first base material, and as a result, the shape retention of the water absorbing sheet is further enhanced, and the amount of reversion can be further reduced. .. Further, in the present invention, the following effects can be expected due to the bulkiness of the first base material. That is, since the first base material is bulky, the absorbed liquid in contact with the liquid absorption surface of the first base material quickly flows into the lower water absorption layer and the second base material, and the first base material is used. The amount of liquid remaining on the liquid absorbing surface of the base material can be reduced. Further, when the absorbed liquid reaches the water absorption layer, the liquid is diffused in the surface direction. Therefore, even if a large amount of the liquid is introduced into the water absorption layer, the water absorption layer spreads in the surface direction instead of locally. It will absorb the liquid. That is, the bulky first base material has low water absorption, high liquid permeability, and high liquid diffusivity. As a result, the amount of reversion in the water-absorbent sheet can be reduced. The humidity of the liquid absorbing surface of the first base material can be suppressed, and the discomfort to the skin can be reduced. The bulk density of the first base material is preferably 0.1 g / cm 3 or less. In this specification, the bulk density is a value calculated in Examples described later.
　第１の基材の厚みは、例えば４０％ＲＨ～５０％ＲＨにおいて、好ましくは０．３ｍｍ以上、より好ましくは０．４ｍｍ以上、さらにより好ましくは０．５ｍｍ以上、特に好ましくは０．６ｍｍ以上、最も好ましくは０．７ｍｍ以上である。第１の基材の厚みは、例えば４０％ＲＨ～５０％ＲＨにおいて、好ましくは５ｍｍ以下、より好ましくは４ｍｍ以下、さらにより好ましくは３ｍｍ以下、特に好ましくは２．５ｍｍ以下、最も好ましくは２ｍｍ以下である。第１の基材の厚みがかような範囲であることにより、第１の基材の吸液面と、吸水層および第２の基材との距離が十分に確保でき、いったん吸水層および第２の基材へと達した液が逆戻りするのを有意に低減できる。 The thickness of the first substrate is, for example, 40% RH to 50% RH, preferably 0.3 mm or more, more preferably 0.4 mm or more, still more preferably 0.5 mm or more, and particularly preferably 0.6 mm or more. Most preferably, it is 0.7 mm or more. The thickness of the first substrate is, for example, 40% RH to 50% RH, preferably 5 mm or less, more preferably 4 mm or less, even more preferably 3 mm or less, particularly preferably 2.5 mm or less, and most preferably 2 mm or less. Is. When the thickness of the first base material is within such a range, a sufficient distance between the liquid absorbing surface of the first base material and the water absorbing layer and the second base material can be sufficiently secured, and the water absorbing layer and the first base material are once used. It is possible to significantly reduce the reversion of the liquid that has reached the base material of 2.
　第１の基材の厚みや嵩密度は、第１の基材を構成する材料、第１の基材の製法などによって制御することができ、これらのバランスで第１の基材の厚みや嵩密度が定まる。 The thickness and bulk density of the first base material can be controlled by the material constituting the first base material, the manufacturing method of the first base material, and the like, and the thickness and bulk of the first base material are balanced by these factors. The density is fixed.
　第１の基材は、粒子状吸水剤の透過率（第１の基材に対する粒子状吸水剤の透過率）が好ましくは４０質量％以上、より好ましくは５０質量％以上、さらに好ましくは、好ましい順に、６０質量％以上、７０質量％以上であり、特に好ましくは８０質量％、最も好ましくは９０質量％以上である。なお、透過率の上限は、特に制限されないが、好ましくは９９質量％以下である。第１の基材に対する粒子状吸水剤の透過率がかような範囲であることにより、第１の基材の吸水層と接する側において、粒子状吸水剤が第１の基材内に入り込みやすくなる。これにより、第１の基材中に含まれる水分を粒子状吸水剤が吸収することが可能となり、逆戻りがさらに低減される。なお、本明細書中、第１の基材に対する粒子状吸水剤の透過率は、第１の基材を透過する粒子状吸水剤の比率であり、図２３のとおり、第１の基材上に存在する粒状吸水剤が、後述する所定の条件でふるわれた場合における、第１の基材を通過した粒子状吸水剤の重量により求められ、具体的には後述の実施例に記載の方法で算出される値である。また、透過率に用いられる粒子状吸水剤は、第２の実施形態のように吸水層が複数存在する場合には、各吸水層に含まれる粒子状吸水剤全体を用いる。ここで、第１の基材に対する粒子状吸水剤の透過率は、第１の基材が不織布の場合は、第１の基材を構成する部材の性質、その表面状態、網目構造の複雑さ、繊維径、繊維間の融着状態、目付、厚み等を適宜調整することにより、所望の範囲に調整することができる。例えば、第１の基材が、後述のようにエアスルー不織布を用いるのであればエアスルー不織布の熱処理条件や繊維径及び密度を変更することによって透過率を調整することができる。 The first base material has a particulate water absorbing agent transmittance (permeability of the particulate water absorbing agent with respect to the first base material) of preferably 40% by mass or more, more preferably 50% by mass or more, still more preferably. In this order, it is 60% by mass or more, 70% by mass or more, particularly preferably 80% by mass or more, and most preferably 90% by mass or more. The upper limit of the transmittance is not particularly limited, but is preferably 99% by mass or less. Since the transmittance of the particulate water-absorbing agent with respect to the first base material is within such a range, the particulate water-absorbing agent easily enters the first base material on the side in contact with the water-absorbing layer of the first base material. Become. As a result, the water-absorbing agent in the form of particles can absorb the water contained in the first base material, and the reversion is further reduced. In the present specification, the transmittance of the particulate water-absorbing agent with respect to the first base material is the ratio of the particulate water-absorbing agent that permeates the first base material, and as shown in FIG. 23, on the first base material. The granular water-absorbing agent present in the above is determined by the weight of the particulate water-absorbing agent that has passed through the first base material when it is shaken under predetermined conditions described later, and more specifically, the method described in Examples described later. It is a value calculated by. Further, as the particulate water absorbing agent used for the transmittance, when a plurality of water absorbing layers are present as in the second embodiment, the entire particulate water absorbing agent contained in each water absorbing layer is used. Here, the transmittance of the particulate water absorbing agent with respect to the first base material is determined by the properties of the members constituting the first base material, the surface state thereof, and the complexity of the network structure when the first base material is a non-woven fabric. , Fiber diameter, fusion state between fibers, basis weight, thickness, etc. can be adjusted to a desired range. For example, if an air-through non-woven fabric is used as the first base material as described later, the transmittance can be adjusted by changing the heat treatment conditions, fiber diameter and density of the air-through non-woven fabric.
　「基材を構成する材料」
　第１の基材を構成する材料としては、例えば、紙（衛生用紙、例えばティッシュペーパー、トイレットペーパーおよびタオル用紙）、ネット、不織布、織布、フィルム等が挙げられる。中でも、透水性の観点から、少なくとも第１の基材は、好ましくは不織布が使用される。 "Materials that make up the base material"
Examples of the material constituting the first base material include paper (sanitary paper, for example, tissue paper, toilet paper and towel paper), net, non-woven fabric, woven cloth, film and the like. Above all, from the viewpoint of water permeability, a non-woven fabric is preferably used as at least the first base material.
　使用される不織布としては特に限定されないが、液体浸透性、柔軟性および吸水性シートとした際の強度の観点から、ポリエチレン（ＰＥ）、ポリプロピレン（ＰＰ）等のポリオレフィン繊維、ポリエチレンテレフタレート（ＰＥＴ）、ポリトリメチレンテレフタレート（ＰＴＴ）、ポリエチレンナフタレート（ＰＥＮ）等のポリエステル繊維、ナイロン等のポリアミド繊維、レーヨン繊維、その他の合成繊維からなる不織布や、綿、絹、麻、パルプ（セルロース）繊維等が混合されて製造された不織布等が挙げられる。 The non-woven fabric used is not particularly limited, but from the viewpoint of liquid permeability, flexibility and strength when made into a water-absorbent sheet, polyolefin fibers such as polyethylene (PE) and polypropylene (PP), polyethylene terephthalate (PET), and the like. Non-woven fabrics made of polyester fibers such as polytrimethylene terephthalate (PTT) and polyethylene naphthalate (PEN), polyamide fibers such as nylon, rayon fibers, and other synthetic fibers, cotton, silk, linen, pulp (cellulose) fibers, etc. Examples thereof include non-woven fabrics produced by mixing.
　第１の基材として用いられうる不織布の材質としては、レーヨン繊維、ポリオレフィン繊維、ポリエステル繊維、パルプ繊維およびこれらが混合された繊維などが好ましく、ポリオレフィン繊維であることがより好ましい。これらの繊維は親水化処理が施されていてもよい。 As the material of the non-woven fabric that can be used as the first base material, rayon fiber, polyolefin fiber, polyester fiber, pulp fiber and a fiber in which these are mixed are preferable, and polyolefin fiber is more preferable. These fibers may be hydrophilized.
　また、第１の基材として用いられうる不織布は、特に限定されるものではなく、エアスルー法；エアレイド法；スパンボンド法；スパンレース法など、いずれの方法により得られたものであってもよいが、エアスルー法またはエアレイド法で得られたものであることが好ましく、エアスルー法で得られたもの（エアスルー不織布）であることが好ましい。 The non-woven fabric that can be used as the first base material is not particularly limited, and may be obtained by any method such as an air-through method; an air-laid method; a spunbond method; a spunlace method. Is preferably obtained by the air-through method or the air-laid method, and is preferably obtained by the air-through method (air-through non-woven fabric).
　なお、エアスルー法は、ＰＥ／ＰＰやＰＥ／ＰＥＴなどの熱融着可能な複合繊維に熱風を吹きつけて、熱融着を行うとともに、繊維の間に含まれる空気の量を増やし、嵩を高くし、密度を低くする加工のことをいう。また、エアレイド法は、空気の流れに乗せて均一分散させ、金網上に吸い取らせて不織布を作る方法であり、パルプ繊維の分散に空気を利用しているため、嵩を高くし、密度を低くすることができる。第１の基材がエアスルー不織布であることにより、吸収される液が第１の基材の吸液面に接した後、速やかに第１の基材の中へ導入されやすい。すなわち、第１の基材をエアスルー不織布にすることにより、吸水力が低く、通液力の高い第１の基材とすることができ、吸水性シートにおける逆戻り量を有意に低減することができる。 In the air-through method, hot air is blown onto heat-bondable composite fibers such as PE / PP and PE / PET to perform heat-sealing, and the amount of air contained between the fibers is increased to increase the bulk. It refers to processing that increases the density and reduces the density. In addition, the air-laid method is a method in which air is placed on an air flow to uniformly disperse it and then absorbed onto a wire mesh to form a non-woven fabric. Since air is used to disperse pulp fibers, the volume is increased and the density is reduced. can do. Since the first base material is an air-through non-woven fabric, the absorbed liquid is likely to be quickly introduced into the first base material after coming into contact with the liquid absorbing surface of the first base material. That is, by using the air-through non-woven fabric as the first base material, it is possible to use the first base material having low water absorption and high liquid permeability, and the amount of reversion in the water absorption sheet can be significantly reduced. ..
　［２－１－１．中間基材］
　中間基材は第１の基材と第２の基材との間に配置される任意の基材であり、透水性シートである。 [2-1-1. Intermediate base material]
The intermediate base material is an arbitrary base material arranged between the first base material and the second base material, and is a water permeable sheet.
　中間基材の透水係数の好適な範囲は第１の基材の欄に記載したものと同様である。本願の実施例で使用した中間基材（中間不織布）の透水係数は、１×１０－５ｃｍ／ｓｅｃ以上であった。 The preferred range of the hydraulic conductivity of the intermediate substrate is the same as that described in the column of the first substrate. The water permeability coefficient of the intermediate base material (intermediate non-woven fabric) used in the examples of the present application was 1 × 10-5 cm / sec or more.
　中間基材の伸び率は、好ましい順に１０％以上、１５％以上、１７％以上、２０％以上、２２％以上である。中間基材の伸び率の上限は、特に制限されないが、６０％以下であるのが好ましい。中間基材の伸び率がかような範囲であることにより、中間基材が粒子状吸水剤の形状に追随しやすくなり、結果として吸水性シートの保形性がさらに高まり、逆戻り量をさらに低減できる。 The elongation rates of the intermediate base materials are 10% or more, 15% or more, 17% or more, 20% or more, and 22% or more in the preferred order. The upper limit of the elongation rate of the intermediate base material is not particularly limited, but is preferably 60% or less. When the elongation rate of the intermediate base material is within such a range, the intermediate base material can easily follow the shape of the particulate water absorbent, and as a result, the shape retention of the water-absorbent sheet is further improved and the amount of reversion is further reduced. it can.
　また、中間基材の目付量、嵩密度、厚み、粒子状吸水剤の透過率、特定の粒子状吸水剤の透過率に関する好適な範囲は、第１の基材の欄に記載のものと同様である。 Further, the preferable ranges regarding the amount of grain, bulk density, thickness, permeability of the particulate water absorbent, and the transmittance of the specific particulate water absorbent of the intermediate base material are the same as those described in the column of the first base material. Is.
　さらに、中間基材を構成する材料についても、上記第１の基材の欄に記載のものと同様である。 Further, the materials constituting the intermediate base material are the same as those described in the column of the first base material above.
　［２－２．第２の基材］
　第２の基材が、透水性シートであり、かつ、吸液される側の反対側に位置することで、本発明の効果である吸水性シートの性能（逆戻り量、面方向の漏れなど）を充分に発揮することができる。透水性シートにおける透水性は、透水係数（ＪＩＳ　Ａ１２１８：２００９）が１×１０－５ｃｍ／ｓｅｃ以上であることが好ましい。該透水係数は、より好ましくは１×１０－４ｃｍ／ｓｅｃ以上、さらにより好ましくは１×１０－３ｃｍ／ｓｅｃ以上、特に好ましくは１×１０－２ｃｍ／ｓｅｃ以上、最も好ましくは１×１０－１ｃｍ／ｓｅｃ以上である。 [2-2. Second base material]
Since the second base material is a water-permeable sheet and is located on the opposite side to the side where the liquid is absorbed, the performance of the water-absorbent sheet (return amount, leakage in the plane direction, etc.), which is the effect of the present invention, is achieved. Can be fully demonstrated. The water permeability of the water-permeable sheet preferably has a water permeability coefficient (JIS A1218: 2009) of 1 × 10-5 cm / sec or more. The hydraulic conductivity is more preferably 1 × 10 -4 cm / sec or more, even more preferably 1 × 10 -3 cm / sec or more, particularly preferably 1 × 10 −2 cm / sec or more, and most preferably 1 × It is 10 -1 cm / sec or more.
　また、第２の基材の厚みは、例えば４０％ＲＨ～５０％ＲＨにおいて、好ましくは０．０５ｍｍ以上、より好ましくは０．０８ｍｍ以上、さらにより好ましくは０．１ｍｍ以上、特に好ましくは０．２ｍｍ以上、最も好ましくは０．３ｍｍ以上である。第２の基材の厚みは、例えば４０％ＲＨ～５０％ＲＨにおいて、好ましくは０．９ｍｍ未満、より好ましくは０．８ｍｍ以下、さらにより好ましくは０．７ｍｍ以下、特に好ましくは０．６ｍｍ以下、最も好ましくは０．５ｍｍ以下である。 The thickness of the second substrate is, for example, 40% RH to 50% RH, preferably 0.05 mm or more, more preferably 0.08 mm or more, still more preferably 0.1 mm or more, and particularly preferably 0. It is 2 mm or more, most preferably 0.3 mm or more. The thickness of the second substrate is, for example, 40% RH to 50% RH, preferably less than 0.9 mm, more preferably 0.8 mm or less, still more preferably 0.7 mm or less, and particularly preferably 0.6 mm or less. Most preferably, it is 0.5 mm or less.
　ここで、本発明の一形態によれば、第１の基材の厚みは０．３ｍｍ以上５ｍｍ以下であり、かつ第２の基材の厚みは０．０５ｍｍ以上０．９ｍｍ未満である。第１の基材と第２の基材との厚みを上記範囲に調整することによって、本発明の所期の効果を効率的に奏することができる。また、本発明の一形態によれば、好ましくは第１の基材の厚みは０．４ｍｍ以上４ｍｍ以下であり、かつ第２の基材の厚みは０．０８ｍｍ以上０．８ｍｍ以下であり、より好ましくは第１の基材の厚みは０．５ｍｍ以上３ｍｍ以下であり、かつ第２の基材の厚みは０．１ｍｍ以上０．７ｍｍ以下であり、さらにより好ましくは第１の基材の厚みは０．６ｍｍ以上２．５ｍｍ以下であり、かつ第２の基材の厚みは０．２ｍｍ以上０．６ｍｍ以下であり、特に好ましくは第１の基材の厚みは０．７ｍｍ以上２ｍｍ以下であり、かつ第２の基材の厚みは０．３ｍｍ以上０．５ｍｍ以下である。 Here, according to one embodiment of the present invention, the thickness of the first base material is 0.3 mm or more and 5 mm or less, and the thickness of the second base material is 0.05 mm or more and less than 0.9 mm. By adjusting the thickness of the first base material and the second base material within the above range, the desired effect of the present invention can be efficiently achieved. Further, according to one embodiment of the present invention, the thickness of the first base material is preferably 0.4 mm or more and 4 mm or less, and the thickness of the second base material is 0.08 mm or more and 0.8 mm or less. More preferably, the thickness of the first base material is 0.5 mm or more and 3 mm or less, and the thickness of the second base material is 0.1 mm or more and 0.7 mm or less, and even more preferably the thickness of the first base material. The thickness is 0.6 mm or more and 2.5 mm or less, and the thickness of the second base material is 0.2 mm or more and 0.6 mm or less, and particularly preferably the thickness of the first base material is 0.7 mm or more and 2 mm or less. And the thickness of the second base material is 0.3 mm or more and 0.5 mm or less.
　本発明において、第２の基材の嵩密度は、１ｇ／ｃｍ３以下であるのが好ましく、０．５ｇ／ｃｍ３以下であるのがより好ましく、０．３ｇ／ｃｍ３以下であるのがさらに好ましい。第２の基材の嵩密度は、好ましくは０．０５ｇ／ｃｍ３以上であり、より好ましくは０．０７ｇ／ｃｍ３以上であり、さらに好ましくは０．０８ｇ／ｃｍ３以上である。第２の基材の嵩密度がかような範囲であることにより、第２の基材へ導入された液を保持しやすく、逆戻りが低減できる。 In the present invention, the bulk density of the second substrate is preferably at 1 g / cm 3 or less, more preferably at 0.5 g / cm 3 or less, that is 0.3 g / cm 3 or less More preferred. The bulk density of the second substrate is preferably 0.05 g / cm 3 or more, more preferably 0.07 g / cm 3 or more, further preferably 0.08 g / cm 3 or more. When the bulk density of the second base material is within such a range, the liquid introduced into the second base material can be easily retained, and reversion can be reduced.
　本発明において、第２の基材は、目付量が５～１００ｇ／ｍ２であるのが好ましく、１０～７０ｇ／ｍ２であるのがより好ましく、１５～６５ｇ／ｍ２であるのがさらに好ましくい。 In the present invention, the second base material preferably has a basis weight of 5 to 100 g / m 2 , more preferably 10 to 70 g / m 2 , and further preferably 15 to 65 g / m 2. Preferred.
　第２の基材の厚み、嵩密度、目付量は、第２の基材を構成する材料、第２の基材の製法などによって制御することができ、これらのバランスで第２の基材の厚みや嵩密度が定まる。 The thickness, bulk density, and basis weight of the second base material can be controlled by the material constituting the second base material, the manufacturing method of the second base material, and the like. The thickness and bulk density are determined.
　なお、第１の基材、第２の基材およびラッピングシート（例えば、不織布）の空隙率は、以下の式で測定できる。基材（または、ラッピングシート）に用いられる目付量Ａ（ｇ／ｍ２）、基材（または、ラッピングシート）の厚みＢ（ｍｍ）、基材（または、ラッピングシート）に用いられる素材（例えば、ポレオレフィン）の密度Ｃ（ｇ／ｃｍ３）
　基材（または、シート）の空隙率（％）＝１００－｛（Ａ／１００００）／（Ｂ／１０）｝／Ｃ＊１００ The porosity of the first base material, the second base material and the wrapping sheet (for example, non-woven fabric) can be measured by the following formula. The basis weight A (g / m 2 ) used for the base material (or wrapping sheet), the thickness B (mm) of the base material (or wrapping sheet), and the material (for example, the wrapping sheet) used for the base material (or wrapping sheet). , Poleolefin) density C (g / cm 3 )
Porosity (%) of the base material (or sheet) = 100-{(A / 10000) / (B / 10)} / C * 100
　第２の基材は、液拡散面積が１０００ｍｍ２以上であるのが好ましく、３０００ｍｍ２以上であるのがより好ましく、６０００ｍｍ２以上であるのがさらに好ましく、特に７０００ｍｍ２以上であることが好ましい。また、第２の基材の液拡散面積の上限は特にないが、例えば１０，０００ｍｍ２以下であるのが好ましい。第２の基材の液拡散面積が上記範囲である場合、吸収された液が第２の基材に達した場合に、第２の基材においてその液を面方向に十分に拡散できる。これにより、吸水層を通過した液が多量に第２の基材に導入されても、第２の基材は局所でなく面方向に広がりながら液を吸収することになる。よって、第２の基材において十分に液を吸収および保持することができ、吸水性シートにおける逆戻り量を有意に低減することができる。 The second substrate is preferably a liquid distribution area is 1000 mm 2 or more, more preferably 3000 mm 2 or more, more preferably at 6000 mm 2 or more, and particularly preferably 7000 mm 2 or more. The upper limit of the liquid diffusion area of the second base material is not particularly limited, but is preferably 10,000 mm 2 or less, for example. When the liquid diffusion area of the second base material is within the above range, when the absorbed liquid reaches the second base material, the liquid can be sufficiently diffused in the plane direction on the second base material. As a result, even if a large amount of the liquid that has passed through the water absorption layer is introduced into the second base material, the second base material absorbs the liquid while spreading in the plane direction instead of locally. Therefore, the liquid can be sufficiently absorbed and retained in the second base material, and the amount of reversion in the water-absorbent sheet can be significantly reduced.
　ここで、液拡散面積は、液が基材（例えば、不織布）に接触する際、および／または、液が基材中を、基材の面方向に対して垂直な方向で通過する際に拡散する面方向における面積を意味し、後述の実施例に記載の方法で算出される値である。基材の液拡散面積が大きいほど、その基材が面方向への液の拡散性が高いことを示す。 Here, the liquid diffusion area diffuses when the liquid comes into contact with a base material (for example, a non-woven fabric) and / or when the liquid passes through the base material in a direction perpendicular to the surface direction of the base material. It means the area in the plane direction, and is a value calculated by the method described in Examples described later. The larger the liquid diffusion area of the base material, the higher the liquid diffusibility of the base material in the plane direction.
　「基材を構成する材料」
　第２の基材を構成する材料は、好ましくは不織布が使用される。不織布の材質としては、第１の基材と同様のものが適用でき、例えば、レーヨン繊維、ポリオレフィン繊維、ポリエステル繊維、パルプ繊維およびこれらが混合された繊維などが好ましく、ポリオレフィン繊維であることがより好ましい。 "Materials that make up the base material"
As the material constituting the second base material, a non-woven fabric is preferably used. As the material of the non-woven fabric, the same material as that of the first base material can be applied, and for example, rayon fiber, polyolefin fiber, polyester fiber, pulp fiber and fiber in which these are mixed are preferable, and the non-woven fabric is more preferable. preferable.
　また、第２の基材として用いられうる不織布は、特に限定されるものではなく、エアスルー法；エアレイド法；スパンボンド法；スパンレース法など、いずれの方法により得られたものであってもよいが、エアレイド法で得られたもの（エアレイド不織布）またはスパンレース法で得られたもの（スパンレース不織布）であることが好ましい。なお、スパンレース法は、繊維を高圧水流により攻絡させる方法で、接着剤を使用しない方法である。第２の基材がエアレイド不織布やスパンレース不織布であることにより、吸水性シートにおける逆戻り量を有意に低減することができ、かつ面方向の漏れを有意に低減することができる。 The non-woven fabric that can be used as the second base material is not particularly limited, and may be obtained by any method such as an air-through method; an air-laid method; a spunbond method; a spunlace method. However, it is preferable that the material is obtained by the air-laid method (air-laid non-woven fabric) or the spun-lace method (spun-laced non-woven fabric). The spunlace method is a method in which fibers are entangled with a high-pressure water stream and does not use an adhesive. When the second base material is an air-laid non-woven fabric or a spunlace non-woven fabric, the amount of reversion in the water-absorbent sheet can be significantly reduced, and leakage in the plane direction can be significantly reduced.
　［２－３．吸水層］
　本発明の一実施形態に係る吸水性シートにおける吸水層は、粒子状吸水剤を有する。本発明の一実施形態に係る吸水性シートにおいては、吸水層の中に不織布等の他の基材が存在しないことが好ましい。なお、第２の実施形態のように吸水層が複数存在する場合には、吸水層が同一の組成であってもよいし、異なる組成であってもよい。 [2-3. Water absorption layer]
The water-absorbing layer in the water-absorbing sheet according to the embodiment of the present invention has a particulate water-absorbing agent. In the water-absorbent sheet according to the embodiment of the present invention, it is preferable that no other base material such as a non-woven fabric is present in the water-absorbent layer. When a plurality of water absorbing layers are present as in the second embodiment, the water absorbing layers may have the same composition or different compositions.
　（粒子状吸水剤）
　吸水層は、粒子状吸水剤を含む。なお、別途記載のない限り、吸水剤が複数種類の粒子状吸水剤の混合物である場合は、以下の記載は、当該混合物の物性に関する説明である。すなわち、粒子状吸水剤の物性は、吸水層に含まれるすべての粒子状吸水剤を混合した場合の物性である。また、粒子状吸水剤の物性は、吸水性シートから、綿状パルプなどが混じらないように粒子状吸水剤のみを取り出して物性を測定してもよい。 (Particular water absorbent)
The water absorption layer contains a particulate water absorption agent. Unless otherwise specified, when the water absorbing agent is a mixture of a plurality of types of particulate water absorbing agents, the following description is a description of the physical properties of the mixture. That is, the physical characteristics of the particulate water-absorbing agent are the physical characteristics when all the particulate water-absorbing agents contained in the water-absorbing layer are mixed. Further, the physical characteristics of the particulate water-absorbing agent may be measured by taking out only the particulate water-absorbing agent from the water-absorbent sheet so that cotton-like pulp or the like is not mixed.
　「表面張力」
　表面張力とは、固体や液体の表面積を増加させるのに必要な仕事（自由エネルギー）を単位面積当たりで表したものである。本願でいう表面張力は、粒子状吸水剤を０．９０質量％塩化ナトリウム水溶液中に分散させた際の、水溶液の表面張力をいう。なお、吸水剤の表面張力は、以下の手順により測定する。即ち、十分に洗浄された１００ｍｌのビーカーに２０℃に調整された生理食塩水５０ｍｌを入れ、まず、生理食塩水の表面張力を、表面張力計（ＫＲＵＳＳ社製のＫ１１自動表面張力計）を用いて測定する。次に、２０℃に調整した表面張力測定後の生理食塩水を含んだビーカーに、十分に洗浄された２５ｍｍ長のフッ素樹脂製回転子、および粒子状吸水剤０．５ｇを投入し、５００ｒｐｍの条件で４分間攪拌する。４分後、攪拌を止め、含水した粒子状吸水剤が沈降した後に、上澄み液の表面張力を再度同様の操作を行い測定する。なお、本発明では白金プレートを用いるプレート法を採用し、プレートは各測定前に十分脱イオン水にて洗浄し、かつ、ガスバーナーで加熱洗浄して使用する。 "surface tension"
Surface tension is the work (free energy) required to increase the surface area of a solid or liquid, expressed per unit area. The surface tension referred to in the present application refers to the surface tension of the aqueous solution when the particulate water absorbent is dispersed in the 0.90 mass% sodium chloride aqueous solution. The surface tension of the water absorbing agent is measured by the following procedure. That is, 50 ml of physiological saline adjusted to 20 ° C. was placed in a thoroughly washed 100 ml beaker, and the surface tension of the physiological saline was first measured using a surface tension meter (K11 automatic surface tension meter manufactured by KRUSS). To measure. Next, a fully washed 25 mm long fluororesin rotor and 0.5 g of a particulate water absorbent were placed in a beaker containing a physiological saline solution adjusted to 20 ° C. after measuring the surface tension, at 500 rpm. Stir for 4 minutes under the conditions. After 4 minutes, the stirring is stopped, and after the water-containing particulate water absorbent has settled, the surface tension of the supernatant is measured again by performing the same operation. In the present invention, a plate method using a platinum plate is adopted, and the plate is sufficiently washed with deionized water before each measurement and heated and washed with a gas burner before use.
　本発明の一実施形態に係る吸水性シートにおいて、粒子状吸水剤の表面張力が、以下順に、６０ｍＮ／ｍ以上、６５ｍＮ／ｍ以上、６６ｍＮ／ｍ以上、６７ｍＮ／ｍ以上、６９ｍＮ／ｍ以上、７０ｍＮ／ｍ以上、７１ｍＮ／ｍ以上が好ましく、最も好ましくは７２ｍＮ／ｍ以上である。粒子状吸水剤の吸水性シートへの適用では従来の紙オムツよりも表面張力の影響が表れやすく、表面張力が上記の条件を満たすことにより、吸水性シートにおける逆戻り量を低減することができる。 In the water-absorbent sheet according to the embodiment of the present invention, the surface tension of the particulate water-absorbing agent is 60 mN / m or more, 65 mN / m or more, 66 mN / m or more, 67 mN / m or more, 69 mN / m or more, in the following order. It is preferably 70 mN / m or more, 71 mN / m or more, and most preferably 72 mN / m or more. When the particulate water-absorbing agent is applied to a water-absorbent sheet, the influence of surface tension is more likely to appear than that of conventional paper diapers, and when the surface tension satisfies the above conditions, the amount of reversion in the water-absorbent sheet can be reduced.
　本発明の一実施形態に係る吸水性シートにおいて、粒子状吸水剤の表面張力の上限には特に制限はないが、現実的には７３ｍＮ／ｍ以下である。 In the water-absorbent sheet according to the embodiment of the present invention, the upper limit of the surface tension of the particulate water-absorbent is not particularly limited, but is actually 73 mN / m or less.
　本発明の一実施形態に係る吸水性シートにおいて、粒子状吸水剤のＣＲＣ（無加圧下吸水倍率）は、以下順に、３０ｇ／ｇ以上、３２ｇ／ｇ以上、３３ｇ／ｇ以上、３４ｇ／ｇ以上が好ましく、最も好ましくは３５ｇ／ｇ以上である。粒子状吸水剤のＣＲＣが上記の条件を満たすことにより、吸水性シートにおける逆戻り量を低減することができる。なお、粒子状吸水剤のＣＲＣとは、ＥＲＴ４４１．２－０２により規定されるＣｅｎｔｒｉｆｕｇｅ　Ｒｅｔｅｎｔｉｏｎ　Ｃａｐａｃｉｔｙ（遠心分離機保持容量）の略称であり、粒子状吸水剤の無加圧下吸水倍率（「吸水倍率」と称する場合もある）を意味する。具体的には、粒子状吸水剤０．２ｇを不織布製の袋に入れた後、大過剰の０．９質量％塩化ナトリウム水溶液中に３０分間浸漬して自由膨潤させ、その後、遠心分離機（２５０Ｇ）で水切りした後の吸水倍率（単位；ｇ／ｇ）のことをいう。 In the water-absorbing sheet according to the embodiment of the present invention, the CRC (water absorption ratio under no pressure) of the particulate water-absorbing agent is 30 g / g or more, 32 g / g or more, 33 g / g or more, 34 g / g or more in the following order. Is preferable, and most preferably 35 g / g or more. When the CRC of the particulate water absorbing agent satisfies the above conditions, the amount of reversion in the water absorbing sheet can be reduced. The CRC of the particulate water absorbing agent is an abbreviation for Centrifuge Retention Capacity (centrifuge holding capacity) defined by ERT441.2-02, and the water absorption ratio of the particulate water absorbing agent under no pressure (“water absorption ratio””. It may also be called). Specifically, 0.2 g of the particulate water absorbent is placed in a non-woven fabric bag, and then immersed in a large excess of 0.9 mass% sodium chloride aqueous solution for 30 minutes for free swelling, and then a centrifuge (centrifuge). It refers to the water absorption ratio (unit: g / g) after draining with 250G).
　「粒子形状」
　本発明の一実施形態に係る吸水性シートにおいて粒子状吸水剤は、その粒子形状に制限はなく、例えば、球状の粒子状吸水剤（及びその造粒物）であってもよい。好ましい実施形態としては、粒子状吸水剤は、不定形破砕状であることが好ましい。ここで、不定形破砕状とは、形状が一定でない破砕状の粒子である。逆相懸濁重合や気相重合で得られた球状粒子に比べて不定形破砕状では基材へ固定を容易にすることができるからである。本発明の一実施形態に係る粒子状吸水剤は、好ましくは水溶液重合における粉砕物である。一方、粉砕工程を経ない場合、代表的には逆相懸濁重合や重合モノマーを噴霧し重合するような液滴重合等によって得られる球状の粒子または球状粒子の造粒物は、不定形破砕状ではない。本発明の実施形態において、粒子状吸水剤の形状が不定形破砕状であると、平均真円度の高いもの（例えば、球形のもの）と比べて吸水性シートの形状保持がなされやすい。本発明の実施形態において、粒子状吸水剤の平均真円度は、０．７０以下であることが好ましく、０．６０以下であることがより好ましく、０．５５以下であることがさらに好ましい。 "Particle shape"
In the water-absorbent sheet according to the embodiment of the present invention, the particle-like water-absorbent is not limited in its particle shape, and may be, for example, a spherical particle-like water-absorbent (and its granulated product). In a preferred embodiment, the particulate water absorbent is preferably in the form of amorphous crushed material. Here, the amorphous crushed particles are crushed particles having a non-constant shape. This is because the amorphous crushed particles can be easily fixed to the substrate as compared with the spherical particles obtained by reverse phase suspension polymerization or vapor phase polymerization. The particulate water absorbent according to one embodiment of the present invention is preferably a pulverized product in aqueous solution polymerization. On the other hand, when not undergoing the pulverization step, spherical particles or granulated products of spherical particles obtained by reverse phase suspension polymerization or droplet polymerization such as spraying and polymerizing a polymerization monomer are typically crushed into an indefinite form. Not in shape. In the embodiment of the present invention, when the shape of the particulate water absorbing agent is amorphous and crushed, the shape of the water absorbing sheet is more likely to be maintained as compared with the one having a high average roundness (for example, a spherical one). In the embodiment of the present invention, the average roundness of the particulate water absorbent is preferably 0.70 or less, more preferably 0.60 or less, and further preferably 0.55 or less.
　平均真円度の算出方法は以下のとおりである。ランダムに１００個以上の粒子状吸水剤を選択し、各粒子状吸水剤を電子顕微鏡（株式会社キーエンス社製　ＶＥ－９８００）（倍率５０倍）で撮影して粒子状吸水剤の画像を取得し、付属の画像解析ソフトを用いて粒子ごとに周囲長および面積を算出した。以下の式： The calculation method of the average roundness is as follows. 100 or more particulate water absorbents are randomly selected, and each particulate water absorbent is photographed with an electron microscope (VE-9800 manufactured by Keyence Co., Ltd.) (magnification 50 times) to obtain an image of the particulate water absorbent. , The peripheral length and area were calculated for each particle using the attached image analysis software. The following formula:
Figure JPOXMLDOC01-appb-M000011
Figure JPOXMLDOC01-appb-M000011
で各粒子の真円度を求め、得られた値の平均値を平均真円度として算出する。 The roundness of each particle is obtained with, and the average value of the obtained values is calculated as the average roundness.
　「粒子径」
　本発明の一実施形態に係る粒子状吸水剤（もしくは、粒子状の吸水性樹脂、吸水性樹脂粒子）の粒子径は、ＥＲＴ４２０．２－０２に規定される「ＰＳＤ」の測定方法に従って得られた重量平均粒子径であり、１５０～６００μｍであってよい。本発明において、重量平均粒子径は、後述の実施例に記載の方法で算出される値である。 "Particle size"
The particle size of the particulate water-absorbing agent (or particulate water-absorbent resin, water-absorbent resin particles) according to the embodiment of the present invention is obtained according to the measurement method of "PSD" specified in ERT420.2-02. The weight average particle size is 150 to 600 μm. In the present invention, the weight average particle size is a value calculated by the method described in Examples described later.
　粒子状吸水剤の製造方法は、所望の物性を有する吸水剤の製造方法であれば、特に限定されず、例えば、実施例に記載の公報等を参酌して適宜製造することができる。 The method for producing the particulate water-absorbing agent is not particularly limited as long as it is a method for producing the water-absorbing agent having desired physical properties, and for example, it can be appropriately produced in consideration of the publications described in the examples.
　〔２－４．ラッピングシート〕
　本発明の一実施形態に係る吸水性シートにおいて、少なくとも、第１の基材の表面に配置させるラッピングシートを有することが好ましい。ラッピングシートは、第１の基材の表面に配置されていればよいが、ラッピングシートが、第１の基材の側面と、吸水層の側面とを覆うように配置されるのがより好ましく、第１の基材の側面と、吸水層の側面と、第２の基材の側面とを覆い、第２の基材の吸収される液が導入される側とは反対側の面の一部または全体を覆うのがさらに好ましい。 [2-4. Wrapping sheet]
In the water-absorbent sheet according to the embodiment of the present invention, it is preferable to have at least a wrapping sheet to be arranged on the surface of the first base material. The wrapping sheet may be arranged on the surface of the first base material, but it is more preferable that the wrapping sheet is arranged so as to cover the side surface of the first base material and the side surface of the water absorption layer. A part of the side surface of the first base material, the side surface of the water absorption layer, and the side surface of the second base material, which are opposite to the side on which the liquid to be absorbed of the second base material is introduced. Or it is more preferable to cover the whole.
　本発明の好ましい実施形態としては、吸水性シートは、ラッピングシートを備え、ラッピングシートは、透水性シートであり、かつ、少なくとも、第１の基材の表面（吸液される側）に位置する。 In a preferred embodiment of the present invention, the water-absorbent sheet includes a wrapping sheet, and the wrapping sheet is a water-permeable sheet and is located at least on the surface (the side to be absorbed) of the first base material. ..
　また、ラッピングシートの厚みは、例えば４０％ＲＨ～５０％ＲＨにおいて、好ましくは０．００１ｍｍ以上、より好ましくは０．００５ｍｍ以上、さらにより好ましくは０．０１ｍｍ以上、特に好ましくは０．１ｍｍ以上、最も好ましくは０．２ｍｍ以上である。ラッピングシートの厚みは、例えば４０％ＲＨ～５０％ＲＨにおいて、好ましくは０．９ｍｍ未満、より好ましくは０．８ｍｍ以下、さらにより好ましくは０．７ｍｍ以下、特に好ましくは０．６ｍｍ以下、最も好ましくは０．５ｍｍ以下である。 The thickness of the wrapping sheet is, for example, 40% RH to 50% RH, preferably 0.001 mm or more, more preferably 0.005 mm or more, still more preferably 0.01 mm or more, and particularly preferably 0.1 mm or more. Most preferably, it is 0.2 mm or more. The thickness of the wrapping sheet is, for example, 40% RH to 50% RH, preferably less than 0.9 mm, more preferably 0.8 mm or less, still more preferably 0.7 mm or less, particularly preferably 0.6 mm or less, most preferably. Is 0.5 mm or less.
　本発明において、ラッピングシートの嵩密度は、１ｇ／ｃｍ３以下であるのが好ましく、０．５ｇ／ｃｍ３以下であるのがより好ましく、０．３ｇ／ｃｍ３以下であるのがさらに好ましい。ラッピングシートの嵩密度は、好ましくは０．１ｇ／ｃｍ３以上であり、より好ましくは０．１２ｇ／ｃｍ３以上であり、さらに好ましくは０．１３ｇ／ｃｍ３以上である。 In the present invention, the bulk density of the wrapping sheet is preferably at 1 g / cm 3 or less, more preferably at 0.5 g / cm 3 or less, even more preferably at 0.3 g / cm 3 or less. The bulk density of the wrapping sheet is preferably 0.1 g / cm 3 or more, more preferably 0.12 g / cm 3 or more, further preferably 0.13 g / cm 3 or more.
　本発明において、ラッピングシートは、目付量が５～１００ｇ／ｍ２であるのが好ましく、５～７０ｇ／ｍ２であるのがより好ましく、１０～６５ｇ／ｍ２であるのがさらに好ましくい。 In the present invention, the basis weight of the wrapping sheet is preferably 5 to 100 g / m 2 , more preferably 5 to 70 g / m 2 , and even more preferably 10 to 65 g / m 2 .
　ラッピングシートの厚み、嵩密度、目付量は、ラッピングシートを構成する材料、ラッピングシートの製法などによって制御することができ、これらのバランスでラッピングシートの厚みや嵩密度が定まる。 The thickness, bulk density, and basis weight of the wrapping sheet can be controlled by the material constituting the wrapping sheet, the manufacturing method of the wrapping sheet, etc., and the thickness and bulk density of the wrapping sheet are determined by these balances.
　「ラッピングシートを構成する材料」
　ラッピングシートを構成する材料は、上述したラッピングシートを設ける目的を達成できるのであれば特に制限されないが、例えば、紙（衛生用紙、例えばティッシュペーパー、トイレットペーパーおよびタオル用紙）、ネット、不織布、織布、フィルム等が挙げられる。 "Materials that make up the wrapping sheet"
The material constituting the wrapping sheet is not particularly limited as long as the above-mentioned purpose of providing the wrapping sheet can be achieved, and for example, paper (sanitary paper such as tissue paper, toilet paper and towel paper), net, non-woven fabric, woven cloth. , Film and the like.
　使用される不織布としては特に限定されないが、液体浸透性、柔軟性および吸水性シートとした際の強度の観点から、ポリエチレン（ＰＥ）、ポリプロピレン（ＰＰ）等のポリオレフィン繊維、ポリエチレンテレフタレート（ＰＥＴ）、ポリトリメチレンテレフタレート（ＰＴＴ）、ポリエチレンナフタレート（ＰＥＮ）等のポリエステル繊維、ナイロン等のポリアミド繊維、レーヨン繊維、その他の合成繊維からなる不織布や、綿、絹、麻、パルプ（セルロース）繊維等が混合されて製造された不織布等が挙げられる。 The non-woven fabric used is not particularly limited, but from the viewpoint of liquid permeability, flexibility and strength when made into a water-absorbent sheet, polyolefin fibers such as polyethylene (PE) and polypropylene (PP), polyethylene terephthalate (PET), and the like. Non-woven fabrics made of polyester fibers such as polytrimethylene terephthalate (PTT) and polyethylene naphthalate (PEN), polyamide fibers such as nylon, rayon fibers, and other synthetic fibers, cotton, silk, linen, pulp (cellulose) fibers, etc. Examples thereof include non-woven fabrics produced by mixing.
　ラッピングシートとして用いられうる不織布の材質としては、レーヨン繊維、ポリオレフィン繊維、ポリエステル繊維、パルプ繊維およびこれらが混合された繊維などが好ましく、ポリオレフィン繊維であることがより好ましい。これらの繊維は親水化処理が施されていてもよい。 As the material of the non-woven fabric that can be used as the wrapping sheet, rayon fiber, polyolefin fiber, polyester fiber, pulp fiber and a fiber in which these are mixed are preferable, and polyolefin fiber is more preferable. These fibers may be hydrophilized.
　ラッピングシートとして用いられうる不織布は、特に限定されるものではなく、エアスルー法；エアレイド法；スパンボンド法；スパンレース法など、いずれの方法により得られたものであってもよいが、スパンボンド法で得られたもの（スパンボンド不織布）であることが好ましい。紙オムツ等の吸収性物品を履いた幼児が座っている場面のように、吸水性シートに加重がかかっている状態でも（加圧している状態でも）、吸水性シートに吸収された尿水が、シートからにじみ出ないように（いわゆる逆戻りしないように）撥水性を有するラッピングシートが好ましく、例えば、スパンボンド不織布が好ましい。なお、スパンボンド不織布の製造法は、原料樹脂を溶融・紡糸させ得られる連続した長い繊維を直接集積してフリースを形成する方法である。原料樹脂としては、ポリエチレン、ポリプロピレン、ポリ乳酸などが挙げられる。 The non-woven fabric that can be used as the wrapping sheet is not particularly limited, and may be obtained by any method such as an air-through method; an air-laid method; a spunbond method; a spunlace method, but the spunbond method. It is preferable that it is the one obtained in (Spunbonded non-woven fabric). The urine water absorbed by the water-absorbent sheet is absorbed even when the water-absorbent sheet is loaded (even when it is pressurized), such as when an infant wearing an absorbent item such as a disposable diaper is sitting. A wrapping sheet having water repellency so as not to ooze out from the sheet (so-called reversal) is preferable, and for example, a spunbonded non-woven fabric is preferable. The method for producing a spunbonded non-woven fabric is a method of directly accumulating long continuous fibers obtained by melting and spinning a raw material resin to form a fleece. Examples of the raw material resin include polyethylene, polypropylene, polylactic acid and the like.
　本発明の一形態によれば、第１の基材の製法と、第２の基材の製法と、ラッピングシートの製法とが異なる。このように吸水性シートを構成する各部材の製法を適切に変更することによって、本発明の所期の効果を効率的に奏することができる。本発明の一形態によれば、第１の基材が、エアスルー不織布であり、第２の基材が、エアレイド不織布、スパンレース不織布であり、ラッピングシートが、スパンボンド不織布であり、互いに異なる不織布である。かかる形態によって、本発明の所期の効果を効率的に奏することができる。 According to one embodiment of the present invention, the method for producing the first base material, the method for producing the second base material, and the method for producing the wrapping sheet are different. By appropriately changing the manufacturing method of each member constituting the water-absorbent sheet in this way, the desired effect of the present invention can be efficiently achieved. According to one embodiment of the present invention, the first base material is an air-through non-woven fabric, the second base material is an air-laid non-woven fabric and a spunlace non-woven fabric, and the wrapping sheet is a spunbond non-woven fabric, which are different non-woven fabrics. Is. With such a form, the desired effect of the present invention can be efficiently achieved.
　〔３．吸水性シートの製造方法〕
　本発明の第１および第２の実施形態に係る吸水性シートの製造方法は、（１）第１の基材に粒子状吸水剤を散布する工程、および、（２）第２の基材に粒子状吸水剤を散布する工程、の少なくとも１つを含む。より具体的な製造方法の一例として、第１の実施形態に係る吸水性シートについては、下記（ａ）～（ｄ）の製造方法が挙げられる。第２の実施形態に係る吸水性シートについては、下記（ｅ）～（ｈ）の製造方法が挙げられる。 [3. Manufacturing method of water-absorbent sheet]
The method for producing a water-absorbent sheet according to the first and second embodiments of the present invention includes (1) a step of spraying a particulate water-absorbing agent on a first base material, and (2) a second base material. Includes at least one step of spraying the particulate water absorbent. As an example of a more specific manufacturing method, the following manufacturing methods (a) to (d) can be mentioned for the water-absorbent sheet according to the first embodiment. Examples of the water-absorbent sheet according to the second embodiment include the following production methods (e) to (h).
　（ａ）第１の基材の上に、粒子状吸水剤を筋状に散布する。第２の基材の上に、接着剤を均一に散布する。第１の基材の粒子状吸水剤が散布されている面と、第２の基材の接着剤が散布されている面とが対合するように重ねて、圧着する。圧着は、接着剤の溶融温度付近における加熱圧着が好ましい。 (A) Sprinkle the particulate water absorbent on the first base material in a streak pattern. The adhesive is evenly sprayed onto the second substrate. The surface on which the particulate water absorbing agent of the first base material is sprayed and the surface on which the adhesive of the second base material is sprayed are overlapped and pressure-bonded so as to face each other. The crimping is preferably heat crimping in the vicinity of the melting temperature of the adhesive.
　（ｂ）第２の基材の上に、接着剤を筋状に散布した後、粒子状吸水剤を均一に散布する。第１の基材を、第２の基材の粒子状吸水剤が散布されている面に重ねて、加熱圧着する。 (B) After spraying the adhesive in a streak pattern on the second base material, the particulate water absorbent is uniformly sprayed. The first base material is superposed on the surface of the second base material on which the particulate water absorbing agent is sprayed, and heat-bonded.
　（ｃ）第２の基材の上に、粒子状吸水剤を筋状に散布し、および、好ましくは接着剤を均一に散布し、加熱炉を通過させて、粒子状吸水剤が散逸しない程度に固着させる。第１の基材を、第２の基材の粒子状吸水剤が散布されている面に重ねて、加熱圧着する。 (C) On the second base material, the particulate water absorbent is sprayed in a streak pattern, and preferably the adhesive is uniformly sprayed and passed through a heating furnace so that the particulate water absorbent does not dissipate. To stick to. The first base material is superposed on the surface of the second base material on which the particulate water absorbing agent is sprayed, and heat-bonded.
　（ｄ）第２の基材の上に、接着剤を溶融塗布した後、粒子状吸水剤を筋状に散布して層を形成させる。第１の基材を、第２の基材の粒子状吸水剤が散布されている面に重ねて、ロールプレスなどを用いて圧着する。 (D) After melt-coating the adhesive on the second base material, the particulate water-absorbing agent is sprayed in a streak pattern to form a layer. The first base material is placed on the surface of the second base material on which the particulate water absorbing agent is sprayed, and pressure-bonded using a roll press or the like.
　（ｅ）第１の基材（または中間基材）の上に、粒子状吸水剤を筋状に散布する。中間基材（または第１の基材）の上に、接着剤を均一に散布する。第１の基材（または中間基材）の粒子状吸水剤が散布されている面と、中間基材（または第１の基材）の接着剤が散布されている面とが対合するように重ねて、圧着して第１の基材と中間基材との接合体を得る。第１の基材と中間基材との接合体の中間基材上に、粒子状吸水剤を筋状に散布する。第２の基材の上に、接着剤を均一に散布する。第１の基材と中間基材との接合体の粒子状吸水剤が散布されている面と、第２の基材の接着剤が散布されている面とが対合するように重ねて、圧着する。圧着は、接着剤の溶融温度付近における加熱圧着が好ましい。 (E) Sprinkle the particulate water absorbent on the first base material (or intermediate base material) in a streak pattern. The adhesive is evenly sprayed onto the intermediate substrate (or the first substrate). The surface of the first base material (or intermediate base material) on which the particulate water absorbing agent is sprayed and the surface of the intermediate base material (or the first base material) on which the adhesive is sprayed face each other. To obtain a bonded body of the first base material and the intermediate base material. The particulate water absorbent is sprayed in a streak pattern on the intermediate base material of the bonded body of the first base material and the intermediate base material. The adhesive is evenly sprayed onto the second substrate. The surface of the joint between the first base material and the intermediate base material on which the particulate water-absorbing agent is sprayed and the surface on which the adhesive of the second base material is sprayed are overlapped so as to face each other. Crimping. The crimping is preferably heat crimping in the vicinity of the melting temperature of the adhesive.
　（ｆ）第２の基材の上に、接着剤を均一に散布した後、粒子状吸水剤を筋状に散布する。中間基材を、第２の基材の粒子状吸水剤が散布されている面に重ねて、加熱圧着して中間基材および第２の基材の接合体を得る。中間基材および第２の基材の接合体の中間基材の上に、粒子状吸水剤を筋状に散布する。第１の基材の上に、接着剤を均一に散布する。中間基材および第２の基材の接合体の粒子状吸水剤が散布されている面と、第１の基材の接着剤が散布されている面とが対合するように重ねて、圧着する。 (F) After uniformly spraying the adhesive on the second base material, the particulate water absorbent is sprayed in a streak pattern. The intermediate base material is superposed on the surface of the second base material on which the particulate water absorbing agent is sprayed, and heat-pressed to obtain a bonded body of the intermediate base material and the second base material. The particulate water absorbent is sprayed in a streak pattern on the intermediate base material of the composite of the intermediate base material and the second base material. The adhesive is evenly sprayed onto the first substrate. The surface of the joint of the intermediate base material and the second base material on which the particulate water absorbing agent is sprayed and the surface on which the adhesive of the first base material is sprayed are overlapped and pressure-bonded so as to face each other. To do.
　（ｇ）第２の基材の上に、粒子状吸水剤を筋状に散布し、および、好ましくは接着剤を均一に散布し、加熱炉を通過させて、粒子状吸水剤が散逸しない程度に固着させる。第１の基材を、第２の基材の粒子状吸水剤が散布されている面に重ねて、加熱圧着して中間基材および第２の基材の接合体を得る。中間基材および第２の基材の接合体の中間基材の上に、粒子状吸水剤を筋状に散布し、および、好ましくは接着剤を均一に散布し、加熱炉を通過させて、粒子状吸水剤が散逸しない程度に固着させる。第１の基材を、中間基材および第２の基材の接合体の粒子状吸水剤が散布されている面に重ねて、加熱圧着する。 (G) On the second base material, the particulate water absorbent is sprayed in a streak pattern, and preferably the adhesive is evenly sprayed and passed through a heating furnace so that the particulate water absorbent does not dissipate. To stick to. The first base material is superposed on the surface of the second base material on which the particulate water absorbing agent is sprayed, and heat-pressed to obtain a bonded body of the intermediate base material and the second base material. On the intermediate base material of the joint of the intermediate base material and the second base material, the particulate water absorbent is sprayed in a streak pattern, and preferably the adhesive is uniformly sprayed and passed through a heating furnace. Fix the particulate water absorbent to the extent that it does not dissipate. The first base material is superposed on the surface of the intermediate base material and the joint of the second base material on which the particulate water absorbing agent is sprayed, and heat-bonded.
　（ｈ）第２の基材の上に、接着剤を溶融塗布した後、粒子状吸水剤を筋状に散布して層を形成させる。中間基材を、第２の基材の粒子状吸水剤が散布されている面に重ねて、ロールプレスなどを用いて圧着して中間基材および第２の基材の接合体を得る。中間基材および第２の基材の接合体の第１の基材の上に、接着剤を溶融塗布した後、粒子状吸水剤を筋状に散布して層を形成させる。第１の基材を、中間基材および第２の基材の接合体の粒子状吸水剤が散布されている面に重ねて、ロールプレスなどを用いて圧着する。 (H) After melt-coating the adhesive on the second base material, the particulate water-absorbing agent is sprayed in a streak pattern to form a layer. The intermediate base material is superposed on the surface of the second base material on which the particulate water absorbing agent is sprayed, and pressure-bonded using a roll press or the like to obtain a bonded body of the intermediate base material and the second base material. After melt-coating the adhesive on the first base material of the composite of the intermediate base material and the second base material, the particulate water absorbent is sprayed in a streak pattern to form a layer. The first base material is placed on the surface of the intermediate base material and the joint of the second base material on which the particulate water absorbing agent is sprayed, and pressure-bonded using a roll press or the like.
　これらの方法のなかでは、製造方法の簡便さと製造効率の高さの観点から、第１の実施形態では（ａ）および（ｂ）の方法が好ましく、第２の実施形態では（ｅ）および（ｆ）の方法が好ましい。なお、第１の実施形態においては（ａ）～（ｄ）、第２の実施形態においては（ｅ）～（ｈ）の方法を併用して、吸水性シートを製造することもできる。 Among these methods, the methods (a) and (b) are preferable in the first embodiment, and the methods (e) and (e) and (in the second embodiment) are preferable from the viewpoint of simplicity of the manufacturing method and high manufacturing efficiency. The method of f) is preferable. The water-absorbent sheet can also be produced by using the methods (a) to (d) in the first embodiment and the methods (e) to (h) in the second embodiment in combination.
　ここで、本発明において、粒子状吸水剤を筋状に散布する方法としては、特に制限されないが、例えば、型紙を用いることにより筋状に散布することができる。具体的には、吸水性シートと同じサイズで、一定の幅および長さで並んだ縞状のパターンで繰りぬかれたプレートを型紙として用いる。この型紙を、粒子状吸水剤を散布したい基材上に載せ、繰りぬかれた穴の部分に対して、粒子状吸水剤を散布する。粒子状吸水剤を散布後、型紙を取りはずすと、基材上には粒子状吸水剤が筋状に散布された状態となる。 Here, in the present invention, the method of spraying the particulate water absorbing agent in a streak pattern is not particularly limited, but for example, it can be sprayed in a streak pattern by using a paper pattern. Specifically, a plate having the same size as the water-absorbent sheet and hollowed out in a striped pattern arranged in a certain width and length is used as a paper pattern. This paper pattern is placed on a base material on which the particulate water absorbing agent is to be sprayed, and the particulate water absorbing agent is sprayed on the hollowed-out holes. When the paper pattern is removed after spraying the particulate water-absorbing agent, the particulate water-absorbing agent is sprayed in a streak pattern on the base material.
　また、スクリーン印刷等により接着剤を基材上に縞状に塗布し、当該基材上に粒子状吸水剤を散布した後、基材上の接着剤と接触していない粒子状吸水剤を払い落とすことにより、基材上に粒子状吸水剤を筋状に散布することもできる。 In addition, the adhesive is applied in stripes on the base material by screen printing or the like, the particulate water absorbent is sprayed on the base material, and then the particulate water absorbent that is not in contact with the adhesive on the base material is removed. By dropping it, the particulate water-absorbing agent can be sprayed on the base material in a streak pattern.
　また、図１８、図１９のように吸水性シートがラッピングシートを備えている形態においては、（３）第１の基材と吸水層と第２の基材と、または第１の基材と吸水層と中間基材と吸水層と第２の基材とを、第１の基材上に配置させたラッピングシートにより覆う工程を含む。例えば、上記（ａ）もしくは（ｂ）または（ｅ）もしくは（ｆ）の工程を経て得られた第１の基材と吸水層と第２の基材とが圧着されたシート、または第１の基材と吸水層と中間基材と吸水層と第２の基材とが圧着されたシートを、第１の基材を下にして、ラッピングシートの上に載せ、上面である第２の基材（吸水層が圧着されていない側の面）に接着剤を散布し、第１の基材からはみ出したラッピングシートの余った部分を折り曲げて、第２の基材の接着剤面とラッピングシートが接触するように包み、上下が逆になるようひっくり返した後、加圧圧着することで、ラッピングシートを備えた吸水性シートを得ることができる。 Further, in the form in which the water-absorbent sheet includes the wrapping sheet as shown in FIGS. 18 and 19, (3) the first base material, the water-absorbent layer, the second base material, or the first base material. The step of covering the water absorption layer, the intermediate base material, the water absorption layer, and the second base material with a wrapping sheet arranged on the first base material is included. For example, a sheet in which the first base material, the water absorption layer, and the second base material obtained through the steps (a) or (b) or (e) or (f) are pressure-bonded, or the first base material. A sheet in which a base material, a water absorption layer, an intermediate base material, a water absorption layer, and a second base material are pressure-bonded is placed on a wrapping sheet with the first base material facing down, and a second base which is an upper surface. The adhesive is sprayed on the material (the surface on the side where the water absorption layer is not crimped), and the remaining part of the wrapping sheet protruding from the first base material is bent to form the adhesive surface and the wrapping sheet of the second base material. A water-absorbent sheet having a wrapping sheet can be obtained by wrapping the sheets so that they come into contact with each other, turning them upside down, and then pressure-bonding them.
　以上に説明した以外の工程として、吸水性シートの触感を改善し、液体吸収性能を向上させる目的で、吸水性シートにエンボス加工を施してもよい。エンボス加工は、第１の基材および第２の基材を圧着する際に同時に施してもよいし、シート製造後に施してもよい。また、ラッピングシートにエンボス加工を施してもよい。 As a process other than those described above, the water-absorbent sheet may be embossed for the purpose of improving the tactile sensation of the water-absorbent sheet and improving the liquid absorption performance. The embossing may be performed at the same time when the first base material and the second base material are crimped, or may be performed after the sheet is manufactured. Further, the wrapping sheet may be embossed.
　本発明の一実施形態に係る吸水性シートの製造方法においては、添加剤（消臭剤、繊維、抗菌剤、ゲル安定剤など）を適宜配合してもよい。添加剤の配合量は、粒子状吸水剤の質量に対して好ましくは０～５０質量％であり、より好ましくは１～１０質量％である。上記製造方法においては、予め添加剤を混合した粒子状吸水剤を用いてもよいし、製造工程の途中で添加剤を添加してもよい。 In the method for producing a water-absorbent sheet according to an embodiment of the present invention, additives (deodorant, fiber, antibacterial agent, gel stabilizer, etc.) may be appropriately added. The blending amount of the additive is preferably 0 to 50% by mass, and more preferably 1 to 10% by mass with respect to the mass of the particulate water absorbing agent. In the above-mentioned production method, a particulate water-absorbing agent mixed with an additive in advance may be used, or an additive may be added in the middle of the production process.
　製造される吸水性シートの寸法は、適宜設計されうる。通常は、横幅が３～１０ｍ、長さが数１０ｍ～数１０００ｍ（連続シートまたはロールの状態において）である。製造された吸水性シートは、目的（使用される吸収体の大きさ）に応じて裁断して用いられる。 The dimensions of the manufactured water-absorbent sheet can be designed as appropriate. Usually, the width is 3 to 10 m and the length is several tens to several thousand m (in the state of continuous sheet or roll). The manufactured water-absorbent sheet is cut and used according to the purpose (size of the absorbent body used).
　上記に例示した以外にも、吸水性シートの製造方法は、例えば以下の特許文献に開示されている：国際公開第２０１２／１７４０２６号、国際公開第２０１３／０７８１０９号、国際公開第２０１５／０４１７８４号、国際公開第２０１１／１１７１８７号、国際公開第２０１２／００１１１７号、国際公開第２０１２／０２４４４５号、国際公開第２０１０／００４８９４号、国際公開第２０１０／００４８９５号、国際公開第２０１０／０７６８５７号、国際公開第２０１０／０８２３７３号、国際公開第２０１０／１１３７５４号、国際公開第２０１０／１４３６３５号、国際公開第２０１１／０４３２５６号、国際公開第２０１１／０８６８４１号、国際公開第２０１１／０８６８４２号、国際公開第２０１１／０８６８４３号、国際公開第２０１１／０８６８４４号、国際公開第２０１１／１１７９９７号、国際公開第２０１１／１１８４０９号、国際公開第２０１１／１３６０８７号、国際公開第２０１２／０４３５４６号、国際公開第２０１３／０９９６３４号、国際公開第２０１３／０９９６３５号、特開２０１０－１１５４０６号、特開２００２－３４５８８３号、特開平６－３１５５０１号、特開平６－１９０００３号、特開平６－１９０００２号、特開平６－１９０００１号、特開平２－２５２５５８号、特開平２－２５２５６０号、特開平２－２５２５６１号。これらの文献に開示されている吸水性シートの製造方法も、適宜参照される。 In addition to those exemplified above, methods for producing water-absorbent sheets are disclosed, for example, in the following patent documents: International Publication No. 2012/174026, International Publication No. 2013/078109, International Publication No. 2015/041784. , International Publication No. 2011/117187, International Publication No. 2012/001117, International Publication No. 2012/0244445, International Publication No. 2010/004894, International Publication No. 2010/004895, International Publication No. 2010/0768557, International Publication No. 2010/0823373, International Publication No. 2010/113754, International Publication No. 2010/143635, International Publication No. 2011/043256, International Publication No. 2011/086841, International Publication No. 2011/088642, International Publication No. 2011/086843, International Publication No. 2011/086844, International Publication No. 2011/1197997, International Publication No. 2011 / 118409, International Publication No. 2011/136807, International Publication No. 2012/0435446, International Publication No. 2013/ 099634, International Publication No. 2013/099635, JP-A-2010-115406, JP-A-2002-345883, JP-A-6-315501, JP-A-6-190003, JP-A-6-190002, JP-A-6- 190001, Japanese Patent Application Laid-Open No. 2-252558, Japanese Patent Application Laid-Open No. 2-252560, Japanese Patent Application Laid-Open No. 2-252561. The methods for producing water-absorbent sheets disclosed in these documents are also referred to as appropriate.
　本発明の一実施形態に係る吸水性シートにおいて、基材同士、または基材と粒子状吸水剤とを固着させる方法としては、（ｉ）圧着によってもよく、（ｉｉ）水、水溶性高分子、溶媒に溶解または分散した各種バインダーによってもよく、（ｉｉｉ）基材自体の材質の融点で基材同士をヒートシールさせてもよく、（ｉｖ）接着剤を使用して固着させてもよい。基材同士、または基材と粒子状吸水剤は、好ましくは、（ｉｖ）接着剤を使用して固着される。 In the water-absorbent sheet according to the embodiment of the present invention, as a method of fixing the base materials to each other or between the base materials and the particulate water-absorbing agent, (i) crimping may be used, and (ii) water or a water-soluble polymer. , Various binders dissolved or dispersed in a solvent may be used, the base materials may be heat-sealed at the melting point of the material of the base material itself (iii), or the base materials may be fixed by using an adhesive (iv). The base materials, or the base material and the particulate water absorbent, are preferably fixed using an (iv) adhesive.
　使用される接着剤は溶液型でもよいが、溶媒除去の手間や残存する溶媒の問題、生産性の問題から、高い生産性と残存溶媒の問題がないホットメルト接着剤が好ましい。本発明でホットメルト接着剤は、予め基材または粒子状吸水剤の表面に含有されていてもよく、別途、ホットメルト接着剤を吸水性シートの製造工程で使用してもよい。ホットメルト接着剤の形態や融点は適宜選択でき、粒子状でもよく、繊維状でよく、ネット状でもよく、フィルム状でもよく、また、加熱によって溶融させた液状でもよい。ホットメルト接着剤の溶融温度または軟化点は５０～２００℃、６０～１８０℃が好ましい。粒子状の接着剤を使用する場合、その粒子径は上記粒子状吸水剤の平均粒子径の０．０１～２倍、０．０２～１倍、０．０５～０．５倍程度の粒子状接着剤が使用される。 The adhesive used may be a solution type, but a hot melt adhesive having high productivity and no problem of residual solvent is preferable because of the trouble of removing the solvent, the problem of the residual solvent, and the problem of productivity. In the present invention, the hot melt adhesive may be contained in advance on the surface of the base material or the particulate water absorbent, or the hot melt adhesive may be separately used in the process of manufacturing the water absorbent sheet. The form and melting point of the hot melt adhesive can be appropriately selected, and may be in the form of particles, fibers, nets, films, or liquids melted by heating. The melting temperature or softening point of the hot melt adhesive is preferably 50 to 200 ° C. and 60 to 180 ° C. When a particulate adhesive is used, its particle size is 0.01 to 2 times, 0.02 to 1 times, and 0.05 to 0.5 times the average particle size of the particulate water absorbent. Adhesive is used.
　本発明の一実施形態に係る吸水性シートの製造においてホットメルト接着剤を使用する場合には、基材（例えば不織布）の上に粒子状吸水剤とホットメルト接着剤との混合物とを均一に散布し、さらにもう１枚の基材を積層してから、ホットメルト接着剤の溶融温度付近で加熱圧着することにより、吸水性シートを製造することができる。 When a hot melt adhesive is used in the production of the water absorbing sheet according to the embodiment of the present invention, a mixture of the particulate water absorbing agent and the hot melt adhesive is uniformly spread on a base material (for example, a non-woven fabric). A water-absorbent sheet can be produced by spraying, laminating another base material, and then heat-pressing the hot melt adhesive near the melting temperature.
　本発明に使用するホットメルト接着剤としては、適宜選択できるが、好ましくは、エチレン－酢酸ビニル共重合体接着剤、スチレン系エラストマー接着剤、ポリオレフィン系接着剤およびポリエステル系接着剤等から選ばれる１種以上が適宜使用できる。 The hot melt adhesive used in the present invention can be appropriately selected, but is preferably selected from ethylene-vinyl acetate copolymer adhesive, styrene elastomer adhesive, polyolefin adhesive, polyester adhesive and the like1 More than seeds can be used as appropriate.
　具体的に、ポリオレフィン系接着剤として、ポリエチレン、ポリプロピレン、アタクチックポリプロピレンが挙げられ、スチレン系エラストマー接着剤としてはスチレン－イソプレンブロック共重合体（ＳＩＳ）、スチレン－ブタジエンブロック共重合体（ＳＢＳ）、スチレン－イソブチレンブロック共重合体（ＳＩＢＳ）、スチレン－エチレン－ブチレン－スチレンブロック共重合体（ＳＥＢＳ）等が挙げられ、共重合ポリオレフィン等、ポリエステル系接着剤としてポリエチレンテレフタレート（ＰＥＴ）、ポリブチレンテレフタレート（ＰＢＴ）、共重合ポリエステル等が挙げられ、エチレン－酢酸ビニル共重合体接着剤として、エチレン－酢酸ビニル共重合体（ＥＶＡ）接着剤；エチレン－アクリル酸エチル共重合体（ＥＥＡ）、エチレン－アクリル酸ブチル共重合体（ＥＢＡ）等が挙げられる。 Specific examples of the polyolefin-based adhesive include polyethylene, polypropylene, and atactic polypropylene, and examples of the styrene-based elastomer adhesive include a styrene-isoprene block copolymer (SIS) and a styrene-butadiene block copolymer (SBS). Examples thereof include styrene-isobutylene block copolymer (SIBS) and styrene-ethylene-butylene-styrene block copolymer (SEBS). Copolymerized polyolefins and the like, polyethylene terephthalate (PET) and polypropylene terephthalate (PET) as polyester-based adhesives ( PBT), copolymerized polyester, etc., and examples thereof include ethylene-vinyl acetate copolymer (EVA) adhesive; ethylene-ethyl acrylate copolymer (EEA), ethylene-acrylic. Examples thereof include an acid butyl copolymer (EBA).
　本発明の一実施形態に係る吸水性シートおよび／またはその製造方法において、吸水性シートが、接着剤を含むことが好ましく、当該接着剤は、ホットメルト接着剤であることが好ましく、接着剤（例えばホットメルト接着剤）の使用量（含有量）は、粒子状吸水剤の質量に対して、３．０倍以下であることが好ましく、０．０１～２．５倍であることがより好ましく、０．０５～２．０倍であることがさらに好ましい。接着剤（特にホットメルトメルト接着剤）の含有量が多すぎると、コスト面や吸水性シートの質量面（紙オムツの質量増）で不利となるだけでなく、粒子状吸水剤が膨潤規定を受けて吸水性シートの吸水能を低下させる可能性もある。 In the water-absorbent sheet and / or the method for producing the same according to an embodiment of the present invention, the water-absorbent sheet preferably contains an adhesive, and the adhesive is preferably a hot-melt adhesive, and the adhesive ( For example, the amount (content) of the hot melt adhesive) is preferably 3.0 times or less, more preferably 0.01 to 2.5 times, the mass of the particulate water absorbent. , 0.05 to 2.0 times, more preferably. If the content of the adhesive (especially hot melt melt adhesive) is too high, not only is it disadvantageous in terms of cost and the mass of the water-absorbent sheet (increased mass of the paper diaper), but also the particulate water-absorbing agent swells. In response, it may reduce the water absorption capacity of the water-absorbent sheet.
　〔４．吸収性物品〕
　本発明の一実施形態に係る吸収性物品は、〔２〕で説明されている吸水性シートを、液体透過性シートおよび液体不透過性シートによって挟持した構造を有している。ここで、液体透過性シートは、第１の基材側に位置し、液体不透過性シートが、第２の基材側に位置している。すなわち、本発明の一実施形態に係る吸収性物品は、本発明の吸水性シートを液体透過性シートと、液体不透過性シートとで挟持することによりなり、液体透過性シートが、第１の基材側に位置し、液体不透過性シートが、前記第２の基材側に位置している。吸収性物品の具体例としては、紙オムツ、失禁パッド、生理用ナプキン、ペットシート、食品用ドリップシート、電力ケーブルの止水剤などが挙げられる。 [4. Absorbent article]
The absorbent article according to one embodiment of the present invention has a structure in which the water-absorbent sheet described in [2] is sandwiched between a liquid-permeable sheet and a liquid-impermeable sheet. Here, the liquid permeable sheet is located on the first base material side, and the liquid permeable sheet is located on the second base material side. That is, the absorbent article according to the embodiment of the present invention is obtained by sandwiching the water-absorbent sheet of the present invention between the liquid-permeable sheet and the liquid-impermeable sheet, and the liquid-permeable sheet is the first. The liquid impermeable sheet is located on the base material side and is located on the second base material side. Specific examples of the absorbent article include paper diapers, incontinence pads, sanitary napkins, pet sheets, food drip sheets, water blocking agents for electric power cables, and the like.
　液体透過性シートおよび液体不透過性シートとしては、吸収性物品の技術分野で公知のものを、特に制限なく用いることができる。また、吸収性物品は、公知の方法によって製造することができる。 As the liquid permeable sheet and the liquid permeable sheet, those known in the technical field of absorbent articles can be used without particular limitation. In addition, the absorbent article can be produced by a known method.
　［実施例］
　本発明を、以下の実施例および比較例を用いてさらに詳細に説明する。ただし、本発明の技術的範囲が以下の実施例のみに制限されるわけではない。また、下記実施例において、特記しない限り、操作は室温（２５℃）／相対湿度４０～５０％ＲＨの条件下で行われた。 [Example]
The present invention will be described in more detail with reference to the following examples and comparative examples. However, the technical scope of the present invention is not limited to the following examples. Further, in the following examples, unless otherwise specified, the operation was performed under the conditions of room temperature (25 ° C.) / relative humidity of 40 to 50% RH.
　なお、以下の実施例においては、吸水層（粒子状吸水剤を含む領域）の上に第１の基材を積層した積層体が第２の基材の上に１層のみ積層される単層形態と、吸水層（粒子状吸水剤を含む領域）の上に第１の基材を積層した積層体が第２の基材の上に２層積層される二層形態と、が開示されている。単層形態および二層形態のどちらにおいても、「上方不織布」と称する場合は、液を直接的に吸収する吸液面を有する第１の基材を意味し、「下方不織布」と称する場合は、第２の基材を意味する。二層形態における液を直接的に吸収する吸液面を有する第１の基材以外の基材は、中間基材であり、ここでは「中間不織布」と称する。 In the following examples, a single layer in which only one layer of the first base material is laminated on the water absorbing layer (region containing the particulate water absorbing agent) is laminated on the second base material. Disclosed are a form and a two-layered form in which a laminate in which a first base material is laminated on a water absorbing layer (a region containing a particulate water absorbing agent) is laminated in two layers on a second base material. There is. In both the single-layer form and the two-layer form, the term "upper nonwoven fabric" means a first substrate having a liquid-absorbing surface that directly absorbs the liquid, and the term "lower nonwoven fabric" is used. , Means a second substrate. The base material other than the first base material having a liquid absorbing surface that directly absorbs the liquid in the two-layer form is an intermediate base material, and is referred to here as an "intermediate nonwoven fabric".
　＜製造例＞
　［製造例１］
　以下の特許に記載の製造例、実施例、比較例を参考に、内部架橋剤量によって、ＣＲＣを適宜調整することで、ポリアクリル酸（塩）系樹脂の粒子状吸水剤（１）、（２）を得た。得られた粒子状吸水剤の物性を表７、表９に示した。 <Manufacturing example>
[Manufacturing Example 1]
By appropriately adjusting the CRC according to the amount of the internal cross-linking agent with reference to the production examples, examples, and comparative examples described in the following patents, the particulate water absorbing agent (1) of the polyacrylic acid (salt) -based resin, ( 2) was obtained. The physical characteristics of the obtained particulate water absorbent are shown in Tables 7 and 9.
　国際公開第２０１４／０３４８９７号
　国際公開第２０１７／１７０６０５号
　国際公開第２０１６／２０４３０２号
　国際公開第２０１４／０５４６５６号
　国際公開第２０１５／１５２２９９号
　国際公開第２０１８／０６２５３９号
　国際公開第２０１２／０４３８２１号。 International Publication No. 2014/034897 International Publication No. 2017/170605 International Publication No. 2016/204302 International Publication No. 2014/054656 International Publication No. 2015/152299 International Publication No. 2018/062539 International Publication No. 2012/043821.
　〔アクリル酸の製造例〕
　市販のアクリル酸（アクリル酸ダイマー２０００ｐｐｍ、酢酸５００ｐｐｍ、プロピオン酸５００ｐｐｍ、ｐ－メトキシフェノール２００ｐｐｍ）を、無堰多孔板５０段を有する高沸点不純物分離塔の塔底に供給して、還流比を１として蒸留し、マレイン酸やアクリル酸からなる二量体（アクリル酸ダイマー）などの除去後、さらに晶析を行なうことで、アクリル酸（アクリル酸ダイマー２０ｐｐｍ、酢酸５０ｐｐｍ、プロピオン酸５０ｐｐｍ、フルフラール１ｐｐｍ以下、プロトアネモニン１ｐｐｍ以下）を得て、さらに蒸留後にｐ－メトキシフェノールを５０ｐｐｍ添加した。 [Acrylic acid production example]
Commercially available acrylic acid (acrylic acid dimer 2000 ppm, acetic acid 500 ppm, propionic acid 500 ppm, p-methoxyphenol 200 ppm) is supplied to the bottom of a high boiling point impurity separation tower having 50 steps of a dam-free perforated plate, and the reflux ratio is set to 1. Acrylic acid (acrylic acid dimer 20 ppm, acetic acid 50 ppm, propionic acid 50 ppm, furfural 1 ppm or less) by distilling as, after removing dimer (acrylic acid dimer) composed of maleic acid and acrylic acid, and further performing crystallization. , Protoanemonin (1 ppm or less) was obtained, and 50 ppm of p-methoxyphenol was further added after distillation.
　〔アクリル酸ナトリウム水溶液の製法〕
　上記アクリル酸１３９０ｇを米国特許５２１０２９８号の実施例９に従い、４８％苛性ソーダを用いて２０～４０℃で中和して、濃度３７％で１００％中和のアクリル酸ナトリウム水溶液を得た。 [Manufacturing method of aqueous sodium acrylate solution]
According to Example 9 of US Pat. No. 5,210,298, 1390 g of the above acrylic acid was neutralized with 48% caustic soda at 20 to 40 ° C. to obtain a 100% neutralized sodium acrylic acid aqueous solution at a concentration of 37%.
　＜粒子状吸水剤（１）＞
　上記アクリル酸の製造例で得られたアクリル酸、該アクリル酸を用いて上記アクリル酸ナトリウム水溶液の製法で得られたアクリル酸ナトリウム水溶液、および脱イオン水を混合して得られた７５モル％の中和率を有するアクリル酸ナトリウムの水溶液５５００ｇ（単量体濃度３５．５質量％）に、ポリエチレングリコールジアクリレート（エチレンオキシドの平均付加モル数９）４．００ｇを溶解し反応液とした。次いで、シグマ型羽根を２本有する内容積１０Ｌのジャケット付きステンレス製双腕型ニーダーに蓋を付けて形成した反応器に、上記反応液を供給し、反応液を３０℃に保ちながら系を窒素ガス置換し、反応液中の溶存酸素を除去した。続いて、反応液を撹拌しながら、過硫酸ナトリウムの１０質量％水溶液２８．６６ｇ及びＬ－アスコルビン酸の１質量％水溶液３５．２８ｇを添加したところ、およそ１分後に重合が開始した。重合を開始して４０分後に１５０μｍ以下の吸水性樹脂微粉末を１８１．５ｇ添加したうえで、ニーダーのブレードを高速回転（１３０ｒｐｍ）で１０分間ゲル解砕してから含水ゲル状重合体を取り出した。得られた含水ゲル状重合体は約１～２ｍｍの粒子に細分化されていた。 <Particular water absorbent (1)>
75 mol% obtained by mixing the acrylic acid obtained in the above production example of acrylic acid, the aqueous sodium acrylate solution obtained by the above method for producing an aqueous sodium acrylate solution using the acrylic acid, and deionized water. 4.00 g of polyethylene glycol diacrylate (average number of moles of ethylene oxide added 9) was dissolved in 5500 g (monomer concentration 35.5% by mass) of an aqueous solution of sodium acrylate having a neutralization rate to prepare a reaction solution. Next, the above reaction solution was supplied to a reactor formed by attaching a lid to a stainless steel double-armed kneader with an internal volume of 10 L having two sigma type blades, and the system was nitrogenized while keeping the reaction solution at 30 ° C. Gas replacement was performed to remove dissolved oxygen in the reaction solution. Subsequently, 28.66 g of a 10 mass% aqueous solution of sodium persulfate and 35.28 g of a 1 mass% aqueous solution of L-ascorbic acid were added while stirring the reaction solution, and the polymerization started after about 1 minute. 40 minutes after the start of polymerization, 181.5 g of water-absorbent resin fine powder of 150 μm or less was added, and the kneader blade was gel-crushed at high speed (130 rpm) for 10 minutes, and then the hydrogel polymer was taken out. It was. The obtained hydrogel polymer was subdivided into particles having a size of about 1 to 2 mm.
　この細分化された含水ゲル状重合体を５０メッシュ（目の大きさ３００μｍ）の金網上に広げ、１７５℃で６５分間熱風乾燥した。次いで、乾燥物をロールミルを用いて粉砕し、さらに目開き６００μｍの金網で分級、調合することにより、平均粒子径３５０μｍの不定形破砕状の吸水性樹脂（１－１）を得た。得られた吸水性樹脂（１－１）１００質量部に、エチレングリコールジグリシジルエーテル０．０３質量部、プロピレングリコール１．０質量部、水３．０質量部からなる表面架橋剤水溶液４．０３質量部を噴霧混合した。上記の混合物を、パドル型混合加熱処理機を用いて、熱媒温度１００℃で４０分間加熱処理して表面架橋された吸水性樹脂（１－２）を得た。得られた表面架橋された吸水性樹脂（１－２）１００質量部に、水３．０質量部を噴霧混合して、密閉容器内で６０℃で１時間硬化させた後、目開き７１０μｍのふるいを通過させて吸水性樹脂（１－３）を得た。吸水性樹脂（１－３）にＡｅｒｏｓｉｌ９０Ｇ（親水性アモルファスシリカ、日本アエロジル社製）を０．３質量部添加して混合することにより得た吸水性樹脂を粒子状吸水剤（１）とした。 This subdivided hydrogel polymer was spread on a wire mesh of 50 mesh (mesh size 300 μm) and dried with hot air at 175 ° C. for 65 minutes. Next, the dried product was pulverized using a roll mill, further classified and blended with a wire mesh having a mesh size of 600 μm to obtain an amorphous crushed water-absorbent resin (1-1) having an average particle diameter of 350 μm. A surface cross-linking agent aqueous solution containing 0.03 parts by mass of ethylene glycol diglycidyl ether, 1.0 part by mass of propylene glycol, and 3.0 parts by mass of water in 100 parts by mass of the obtained water-absorbent resin (1-1) 4.03. The parts by mass were spray-mixed. The above mixture was heat-treated at a heat medium temperature of 100 ° C. for 40 minutes using a paddle-type mixing heat treatment machine to obtain a surface-crosslinked water-absorbent resin (1-2). 3.0 parts by mass of water was spray-mixed with 100 parts by mass of the obtained surface-crosslinked water-absorbent resin (1-2) and cured at 60 ° C. for 1 hour in a closed container, and then the opening was 710 μm. A water-absorbent resin (1-3) was obtained by passing through a sieve. The water-absorbent resin obtained by adding 0.3 parts by mass of Aerosil 90G (hydrophilic amorphous silica, manufactured by Nippon Aerosil Co., Ltd.) to the water-absorbent resin (1-3) and mixing them was used as a particulate water-absorbent resin (1).
　〔粒子状吸水剤の物性の測定方法〕
　＜重量平均粒子径＞
　本発明の一実施形態に係る粒子状吸水剤（もしくは、粒子状の吸水性樹脂、吸水性樹脂粒子）の粒子径は、ＥＲＴ４２０．２－０２に規定される「ＰＳＤ」の測定方法に従って得られた重量平均粒子径である。各粒子状吸水剤の重量平均粒子径は表８、表１０に示す。 [Measuring method of physical properties of particulate water absorbent]
<Weight average particle size>
The particle size of the particulate water-absorbing agent (or particulate water-absorbent resin, water-absorbent resin particles) according to the embodiment of the present invention is obtained according to the measurement method of "PSD" specified in ERT420.2-02. Weight average particle size. The weight average particle diameters of each particulate water absorbent are shown in Tables 8 and 10.
　＜ＣＲＣ（無加圧下吸水倍率）（ＥＲＴ４４１．２－０２）＞
　粒子状吸水剤０．２ｇ（吸水前重量）を不織布製の袋に入れた後、大過剰の０．９質量％塩化ナトリウム水溶液中に３０分間浸漬して自由膨潤させ、その後、遠心分離機（２５０Ｇ）で水切りした後の粒子状吸水剤の吸水後重量を測定する。吸水倍率（単位；ｇ／ｇ）は、「（粒子状吸水剤の吸水後重量－粒子状吸水剤の吸水前重量）／（粒子状吸水剤の吸水前重量）×１００」により求められる。各粒子状吸水剤のＣＲＣは表８、表１０に示す。 <CRC (Unpressurized Water Absorption Magnification) (ERT441.2-02)>
After putting 0.2 g (weight before water absorption) of the particulate water absorbent into a bag made of non-woven fabric, it is immersed in a large excess of 0.9 mass% sodium chloride aqueous solution for 30 minutes to allow free swelling, and then a centrifuge (centrifugal separator). The weight of the particulate water-absorbing agent after draining with 250G) is measured. The water absorption ratio (unit: g / g) is determined by "(weight of the particulate water absorbent after water absorption-weight of the particulate water absorbent before water absorption) / (weight of the particulate water absorbent before water absorption) x 100". The CRC of each particulate water absorbent is shown in Tables 8 and 10.
　＜表面張力＞
　本発明において、表面張力は、粒子状吸水剤を０．９０質量％塩化ナトリウム水溶液中に分散させた際の、水溶液の表面張力を意味する。 <Surface tension>
In the present invention, the surface tension means the surface tension of the aqueous solution when the particulate water absorbent is dispersed in the 0.90 mass% sodium chloride aqueous solution.
　十分に洗浄された１００ｍｌのビーカーに２０℃に調整された生理食塩水５０ｍｌを入れ、まず、生理食塩水の表面張力を、表面張力計（ＫＲＵＳＳ社製のＫ１１自動表面張力計）を用いて測定する。なお、本発明では、白金プレートを用いるプレート法を採用し、プレートは各測定前に十分脱イオン水にて洗浄し、かつ、ガスバーナーで加熱洗浄して使用する。 50 ml of physiological saline adjusted to 20 ° C. is placed in a thoroughly washed 100 ml beaker, and the surface tension of the physiological saline is first measured using a surface tension meter (K11 automatic surface tension meter manufactured by KRUSS). To do. In the present invention, a plate method using a platinum plate is adopted, and the plate is sufficiently washed with deionized water before each measurement and heated and washed with a gas burner before use.
　次に、２０℃に調整した表面張力測定後の生理食塩水を含んだビーカーに、十分に洗浄された２５ｍｍ長のフッ素樹脂製回転子、および粒子状吸水剤０．５ｇを投入し、５００ｒｐｍの条件で４分間攪拌する。４分後、攪拌を止め、含水した粒子状吸水剤が沈降した後に、上澄み液の表面張力を再度同様の操作を行い測定する。ここで、粒子状吸水剤の表面張力（単位：ｍＮ／ｍ）は、生理食塩水に粒子状吸水剤を分散させた際の上澄み液の表面張力により求められる。各粒子状吸水剤の表面張力は表８、表１０に示す。 Next, a fully washed 25 mm long fluororesin rotor and 0.5 g of a particulate water absorbent were placed in a beaker containing a physiological saline solution adjusted to 20 ° C. after measuring the surface tension, at 500 rpm. Stir for 4 minutes under the conditions. After 4 minutes, the stirring is stopped, and after the water-containing particulate water absorbent has settled, the surface tension of the supernatant is measured again by performing the same operation. Here, the surface tension of the particulate water-absorbing agent (unit: mN / m) is determined by the surface tension of the supernatant liquid when the particulate water-absorbing agent is dispersed in physiological saline. The surface tension of each particulate water absorbent is shown in Tables 8 and 10.
　〔実施例〕
　＜型紙の準備＞
　粒子状吸水剤を不織布上に筋状に散布するため、型紙１～６を準備した。型紙１～６は、縦１４ｃｍ、横４４ｃｍの紙に、長手方向に沿って直線状に、粒子状吸水剤の存在領域と、粒子状吸水剤の非存在領域とが形成されるように、粒子状吸水剤の存在領域となる部分に穴を開けた。なお、型紙１～６において、その外周２ｃｍは枠とし、紙を切断しないものとする（すなわち、型紙は、枠を除く領域において、短手方向に端から順に、粒子状吸水剤の存在領域の部分を繰りぬいて穴とする）。型紙１～６により形成される形状（Ｓ－１）～（Ｓ－６）を図２０（ａ）～図２０（ｃ）、図２１（ａ）～図２１（ｃ）に基づいて説明する。図２０（ａ）～図２０（ｃ）、図２１（ａ）～図２１（ｃ）は、単層形態の吸水性シートを短手方向に沿って切断した断面模式図である。なお、形状（Ｓ－１）～（Ｓ－６）は、吸水性シートの短手方向中央部に対して左右対称となるように、粒子状吸水剤１４が含まれる領域と、間隙１５とが形成されている。よって、下記で示す「粒子状吸水剤１４」と「間隙１５」との領域比は、短手方向に沿って左右どちらからでもよい。 〔Example〕
<Preparation of paper pattern>
Patterns 1 to 6 were prepared in order to spray the particulate water absorbing agent on the non-woven fabric in a streak pattern. The patterns 1 to 6 are particles such that a region in which the particulate water-absorbing agent is present and a region in which the particulate water-absorbing agent is not present are formed linearly along the longitudinal direction on a paper having a length of 14 cm and a width of 44 cm. A hole was made in the area where the water absorbent was present. In the paper patterns 1 to 6, the outer circumference 2 cm thereof shall be a frame, and the paper shall not be cut (that is, the paper pattern shall be a region in which the particulate water absorbing agent is present in the region excluding the frame, in order from the end in the lateral direction. Cut out the part to make a hole). The shapes (S-1) to (S-6) formed by the patterns 1 to 6 will be described with reference to FIGS. 20 (a) to 20 (c) and 21 (a) to 21 (c). 20 (a) to 20 (c) and 21 (a) to 21 (c) are schematic cross-sectional views of a single-layer water-absorbent sheet cut along the lateral direction. The shapes (S-1) to (S-6) have a region containing the particulate water absorbing agent 14 and a gap 15 so as to be symmetrical with respect to the central portion of the water absorbing sheet in the lateral direction. It is formed. Therefore, the region ratio between the "particulate water absorbing agent 14" and the "gap 15" shown below may be from either the left or right along the lateral direction.
　図２０（ａ）は、型紙１により形成される（Ｓ－１）形状である。（Ｓ－１）形状は、第１の基材１１と第２の基材１３との間に、「粒子状吸水剤１４：１５ｍｍ、間隙１５：２５ｍｍ、粒子状吸水剤１４：２０ｍｍ、間隙１５：２５ｍｍ、粒子状吸水剤１４：１５ｍｍ」が短手方向に沿って順に形成されている。 FIG. 20A is a (S-1) shape formed by the pattern 1. The shape of (S-1) is as follows: "Particular water absorbing agent 14:15 mm, gap 15:25 mm, particulate water absorbing agent 14:20 mm, gap 15" between the first base material 11 and the second base material 13. : 25 mm, particulate water absorbing agent 14:15 mm ”are formed in order along the lateral direction.
　図２０（ｂ）は、型紙２により形成される（Ｓ－２）形状である。（Ｓ－２）形状は、第１の基材１１と第２の基材１３との間に、「粒子状吸水剤１４：２０ｍｍ、間隙１５：２０ｍｍ、粒子状吸水剤１４：２０ｍｍ、間隙１５：２０ｍｍ、粒子状吸水剤１４：２０ｍｍ」が短手方向に沿って順に形成されている。 FIG. 20 (b) is a (S-2) shape formed by the paper pattern 2. The shape of (S-2) is as follows: "Particular water absorbing agent 14:20 mm, gap 15:20 mm, particulate water absorbing agent 14:20 mm, gap 15" between the first base material 11 and the second base material 13. : 20 mm, particulate water absorbing agent 14:20 mm ”are formed in order along the lateral direction.
　図２０（ｃ）は、型紙３により形成される（Ｓ－３）形状である。（Ｓ－３）形状は、第１の基材１１と第２の基材１３との間に、「粒子状吸水剤１４：１０ｍｍ、間隙１５：３５ｍｍ、粒子状吸水剤１４：１０ｍｍ、間隙１５：３５ｍｍ、粒子状吸水剤１４：１０ｍｍ」が短手方向に沿って順に形成されている。 FIG. 20 (c) is a (S-3) shape formed by the paper pattern 3. The shape of (S-3) is as follows: "Particular water absorbing agent 14:10 mm, gap 15:35 mm, particulate water absorbing agent 14:10 mm, gap 15" between the first base material 11 and the second base material 13. : 35 mm, particulate water absorbent 14:10 mm ”are formed in order along the lateral direction.
　図２１（ａ）は、型紙４により形成される（Ｓ－４）形状である。（Ｓ－４）形状は、第１の基材１１と第２の基材１３との間に、「粒子状吸水剤１４：２５ｍｍ、間隙１５：１０ｍｍ、粒子状吸水剤１４：３０ｍｍ、間隙１５：１０ｍｍ、粒子状吸水剤１４：２５ｍｍ」が短手方向に沿って順に形成されている。 FIG. 21 (a) is a (S-4) shape formed by the paper pattern 4. The shape of (S-4) is as follows: "Particular water absorbing agent 14:25 mm, gap 15:10 mm, particulate water absorbing agent 14:30 mm, gap 15" between the first base material 11 and the second base material 13. : 10 mm, particulate water absorbing agent 14:25 mm ”are formed in order along the lateral direction.
　図２１（ｂ）は、型紙５により形成される（Ｓ－５）形状である。（Ｓ－５）形状は、第１の基材１１と第２の基材１３との間に、「粒子状吸水剤１４：１７．５ｍｍ、間隙１５：１０ｍｍ、粒子状吸水剤１４：１７．５ｍｍ、間隙１５：１０ｍｍ、粒子状吸水剤１４：１７．５ｍｍ、間隙１５：１０ｍｍ、粒子状吸水剤１４：１７．５ｍｍ」が短手方向に沿って順に形成されている。 FIG. 21 (b) is a (S-5) shape formed by the paper pattern 5. The shape of (S-5) is such that between the first base material 11 and the second base material 13, "particulate water absorbing agent 14: 17.5 mm, gap 15:10 mm, particulate water absorbing agent 14:17. "5 mm, gap 15:10 mm, particulate water absorbing agent 14: 17.5 mm, gap 15:10 mm, particulate water absorbing agent 14: 17.5 mm" are formed in this order along the lateral direction.
　図２１（ｃ）は、型紙６により形成される（Ｓ－６）形状である。（Ｓ－６）形状は、第１の基材１１と第２の基材１３との間に、「粒子状吸水剤１４：１０ｍｍ、間隙１５：５ｍｍ、粒子状吸水剤１４：１０ｍｍ、間隙１５：５ｍｍ、粒子状吸水剤１４：１０ｍｍ、間隙１５：５ｍｍ、粒子状吸水剤１４：１０ｍｍ、間隙１５：５ｍｍ、粒子状吸水剤１４：１０ｍｍ、間隙１５：５ｍｍ、粒子状吸水剤１４：１０ｍｍ、間隙１５：５ｍｍ、粒子状吸水剤１４：１０ｍｍ」が短手方向に沿って順に形成されている。 FIG. 21 (c) is a (S-6) shape formed by the paper pattern 6. The shape of (S-6) is as follows: "Particular water absorbing agent 14:10 mm, gap 15: 5 mm, particulate water absorbing agent 14:10 mm, gap 15" between the first base material 11 and the second base material 13. : 5 mm, Particle Water Absorbent 14:10 mm, Gap 15: 5 mm, Particle Water Absorbent 14:10 mm, Gap 15: 5 mm, Particle Water Absorbent 14:10 mm, Gap 15: 5 mm, Particle Water Absorbent 14:10 mm, A gap of 15: 5 mm and a particulate water absorbing agent of 14:10 mm ”are formed in order along the lateral direction.
　［実施例１］
　縦１０ｃｍ、横４０ｃｍに切断した不織布Ａ（エアスルー法で作製されたもの。オレフィンを主成分とし、厚み１．４ｍｍ。中間不織布に相当する）に、型紙１（図２０（ａ）参照）を載せた。型紙１には３つの長方形の穴があり、その穴から型紙１の下の不織布Ａが最大限に見えるように位置を調整した。型紙１の全ての穴の総合面積に対するそれぞれの穴の面積比を計算し、粒子状吸水剤（１）４．５ｇ（散布量：１１２．５ｇ／ｍ２）をそれぞれの穴の面積比で分けて測りとり、それぞれの穴から見える不織布Ａに対して均一に散布した。型紙の上に粒子状吸水剤（１）の一部が散布された場合、粒子状吸水剤（１）を散布している不織布Ａに向かって型紙１を傾けて、粒子状吸水剤を型紙１の穴に落とした。その後、型紙１を不織布Ａから取り外した。 [Example 1]
Pattern 1 (see FIG. 20 (a)) is placed on non-woven fabric A (made by the air-through method, which is mainly composed of olefin and has a thickness of 1.4 mm, which corresponds to an intermediate non-woven fabric) cut into a length of 10 cm and a width of 40 cm. It was. The pattern 1 has three rectangular holes, and the positions are adjusted so that the non-woven fabric A under the pattern 1 can be seen as much as possible from the holes. Calculate the area ratio of each hole to the total area of all the holes of the pattern 1, and divide 4.5 g (spray amount: 112.5 g / m 2 ) of the particulate water absorbent (1) by the area ratio of each hole. It was measured and evenly sprayed on the non-woven fabric A visible from each hole. When a part of the particulate water absorbing agent (1) is sprayed on the paper pattern, the paper pattern 1 is tilted toward the non-woven fabric A on which the particulate water absorbing agent (1) is sprayed, and the particulate water absorbing agent is applied to the paper pattern 1. I dropped it in the hole. Then, the paper pattern 1 was removed from the non-woven fabric A.
　前記の不織布Ａとは別に、縦１０ｃｍ、横４０ｃｍに切断した不織布Ａ（上記不織布Ａと同じものである（厚み１．４ｍｍ）。以下、不織布Ａ２と称する。第１の基材（上方不織布）に相当する）に、スチレンブタジエンゴムを含む接着剤（スプレーのり７７、スリーエムジャパン株式会社製）０．７～０．９ｇを均一に散布（散布量：１７．５～２１．５ｇ／ｍ）した後、不織布Ａの粒子状吸水剤（１）を散布した面と不織布Ａ２の接着剤を散布した面が対合するように（接触するように）重ね、加圧圧着した。 Separately from the non-woven fabric A, the non-woven fabric A cut into a length of 10 cm and a width of 40 cm (the same as the non-woven fabric A (thickness 1.4 mm). Hereinafter referred to as non-woven fabric A2. First base material (upper non-woven fabric)) 0.7 to 0.9 g of an adhesive containing styrene butadiene rubber (spray glue 77, manufactured by 3M Japan Co., Ltd.) was uniformly sprayed (spray amount: 17.5 to 21.5 g / m). After that, the surface on which the particulate water absorbing agent (1) of the nonwoven fabric A was sprayed and the surface on which the adhesive of the nonwoven fabric A2 was sprayed were overlapped (contacted) and pressure-bonded.
　粒子状吸水剤（１）と面していない側の不織布Ａの表面に、型紙１（図２０（ａ）参照）を載せた。型紙１の３つの長方形の穴から、型紙１の下の不織布Ａが最大限に見えるように位置を調整した。型紙１の全ての穴の総合面積に対するそれぞれの穴の面積比を計算し、粒子状吸水剤（１）４．５ｇをそれぞれの穴の面積比で分けて測りとり、それぞれの穴から見える不織布Ａに対して均一に散布した。型紙の上に粒子状吸水剤（１）の一部が散布された場合、粒子状吸水剤（１）を散布している不織布Ａに向かって型紙１を傾けて、粒子状吸水剤を型紙１の穴に落とした。その後、型紙１を不織布Ａから取り外した。 Pattern 1 (see FIG. 20A) was placed on the surface of the non-woven fabric A on the side not facing the particulate water absorbing agent (1). The position was adjusted so that the non-woven fabric A under the pattern 1 could be seen to the maximum through the three rectangular holes of the pattern 1. Calculate the area ratio of each hole to the total area of all the holes of the paper pattern 1, measure 4.5 g of the particulate water absorbent (1) separately by the area ratio of each hole, and measure the non-woven fabric A that can be seen from each hole. Was sprayed evenly. When a part of the particulate water absorbing agent (1) is sprayed on the paper pattern, the paper pattern 1 is tilted toward the non-woven fabric A on which the particulate water absorbing agent (1) is sprayed, and the particulate water absorbing agent is applied to the paper pattern 1. I dropped it in the hole. Then, the paper pattern 1 was removed from the non-woven fabric A.
　縦１０ｃｍ、横４０ｃｍの不織布Ｅ（エアレイド法で作成されたもの。パルプ繊維を主成分とする。厚み０．４ｍｍ。目付量：４７ｇ／ｍ２。第２の基材（下方不織布）に相当する。）に、前記の接着剤０．７～０．９ｇを均一に散布した後、不織布Ａの粒子状吸水剤（１）を散布した面と不織布Ｅの接着剤を散布した面が対合するように（接触するように）重ね、加圧圧着して中間体シートＸを得た。 Non-woven fabric E with a length of 10 cm and a width of 40 cm (made by the airlaid method. The main component is pulp fiber. Thickness 0.4 mm. Metsuke amount: 47 g / m 2. Corresponds to the second base material (lower non-woven fabric). ), After uniformly spraying 0.7 to 0.9 g of the adhesive, the surface on which the particulate water absorbent (1) of the non-woven fabric A is sprayed and the surface on which the adhesive of the non-woven fabric E is sprayed face each other. The intermediate sheet X was obtained by stacking them in such a manner (contacting each other) and pressure-bonding them.
　最後に、中間体シートＸを縦２４ｃｍ、横４０ｃｍに切断した不織布Ｆ（スパンボンド法で作製したもの。オレフィンを主成分とし、厚み０．１ｍｍ。目付量：１３ｇ／ｍ２。嵩密度：０．１５ｇ／ｃｍ３。ラッピングシートに相当）で包み、吸水性シート（１）を得た。 Finally, the non-woven fabric F (made by the spunbond method) obtained by cutting the intermediate sheet X into a length of 24 cm and a width of 40 cm. The main component is olefin, the thickness is 0.1 mm, the basis weight: 13 g / m 2, and the bulk density: 0. .15 g / cm 3 (corresponding to a wrapping sheet) was wrapped to obtain a water-absorbent sheet (1).
　［実施例２］
　縦２４ｃｍ、横４０ｃｍに切断した不織布Ｆ（ラッピングシートに相当）を敷いておき、その上に、縦１０ｃｍ、横４０ｃｍに切断した不織布Ａ（第１の基材に相当）を載せ、不織布Ａの表面に、型紙１（図２０（ａ）参照）を載せた。型紙１の３つの長方形の穴から、型紙１の下の不織布Ａが最大限に見えるように位置を調整した。型紙１の全ての穴の総合面積に対するそれぞれの穴の面積比を計算し、粒子状吸水剤（１）９．０ｇ（散布量：２２５ｇ／ｍ２）をそれぞれの穴の面積比で分けて測りとり、それぞれの穴から見える不織布Ａに対して均一に散布した。型紙の上に粒子状吸水剤（１）の一部が散布された場合、粒子状吸水剤（１）を散布している不織布Ａに向かって型紙１を傾けて、粒子状吸水剤を型紙１の穴に落とした。その後、型紙１を不織布Ａから取り外した。 [Example 2]
Non-woven fabric F (corresponding to a wrapping sheet) cut into a length of 24 cm and a width of 40 cm is laid, and non-woven fabric A (corresponding to a first base material) cut into a length of 10 cm and a width of 40 cm is placed on the non-woven fabric F. A pattern 1 (see FIG. 20 (a)) was placed on the surface. The position was adjusted so that the non-woven fabric A under the pattern 1 could be seen to the maximum through the three rectangular holes of the pattern 1. Calculate the area ratio of each hole to the total area of all the holes of the paper pattern 1, and measure 9.0 g (spray amount: 225 g / m 2 ) of the particulate water absorbent (1) by dividing it by the area ratio of each hole. It was evenly sprayed on the non-woven fabric A visible from each hole. When a part of the particulate water absorbing agent (1) is sprayed on the paper pattern, the paper pattern 1 is tilted toward the non-woven fabric A on which the particulate water absorbing agent (1) is sprayed, and the particulate water absorbing agent is applied to the paper pattern 1. I dropped it in the hole. Then, the paper pattern 1 was removed from the non-woven fabric A.
　縦１０ｃｍ、横４０ｃｍの不織布Ｅ（第２の基材に相当）に、スチレンブタジエンゴムを含む接着剤（スプレーのり７７、スリーエムジャパン株式会社製）を０．７～０．９ｇ均一に散布（散布量：１７．５～２１．５ｇ／ｍ）した後、不織布Ａの粒子状吸水剤（１）を散布した面と不織布Ｅの接着剤を散布した面が対合するように（接触するように）重ね、加圧圧着して中間体シートＹを得た。 0.7 to 0.9 g of an adhesive containing styrene-butadiene rubber (spray glue 77, manufactured by 3M Japan Co., Ltd.) is uniformly sprayed (sprayed) on a non-woven fabric E (corresponding to the second base material) having a length of 10 cm and a width of 40 cm. Amount: 17.5 to 21.5 g / m), so that the surface of the non-woven fabric A sprayed with the particulate water absorbent (1) and the surface sprayed with the adhesive of the non-woven fabric E face each other (contact each other). ) Stacking and pressure crimping to obtain an intermediate sheet Y.
　最後に、中間体シートＹを前記の不織布Ｆで包み、加圧圧着することで、吸水性シート（２）を得た。 Finally, the intermediate sheet Y was wrapped with the above-mentioned non-woven fabric F and pressure-bonded to obtain a water-absorbent sheet (2).
　［実施例３］
　エアスルー不織布Ａの代わりに、厚み０．７ｍｍのエアスルー不織布Ｇを用いた以外は、実施例２と同様にして、吸水性シート（３）を得た。 [Example 3]
A water-absorbent sheet (3) was obtained in the same manner as in Example 2 except that the air-through nonwoven fabric G having a thickness of 0.7 mm was used instead of the air-through nonwoven fabric A.
　［実施例４］
　型紙１の代わりに、型紙２（図２０（ｂ）参照）を用いた以外は、実施例２と同様にして、吸水性シート（４）を得た。 [Example 4]
A water-absorbent sheet (4) was obtained in the same manner as in Example 2 except that the pattern 2 (see FIG. 20B) was used instead of the pattern 1.
　［実施例５］
　型紙１の代わりに、型紙３（図２０（ｃ）参照）を用いた以外は、実施例２と同様にして、吸水性シート（５）を得た。 [Example 5]
A water-absorbent sheet (5) was obtained in the same manner as in Example 2 except that the pattern 3 (see FIG. 20 (c)) was used instead of the pattern 1.
　［実施例６］
　型紙１の代わりに、型紙４（図２１（ａ）参照）を用いた以外は、実施例２と同様にして、吸水性シート（６）を得た。 [Example 6]
A water-absorbent sheet (6) was obtained in the same manner as in Example 2 except that the paper pattern 4 (see FIG. 21 (a)) was used instead of the paper pattern 1.
　［実施例７］
　型紙１の代わりに、型紙５（図２１（ｂ）参照）を用いた以外は、実施例２と同様にして、吸水性シート（７）を得た。 [Example 7]
A water-absorbent sheet (7) was obtained in the same manner as in Example 2 except that the pattern 5 (see FIG. 21 (b)) was used instead of the pattern 1.
　［実施例８］
型紙１の代わりに、型紙６（図２１（ｃ）参照）を用いた以外は、実施例２と同様にして、吸水性シート（８）を得た。 [Example 8]
A water-absorbent sheet (8) was obtained in the same manner as in Example 2 except that the paper pattern 6 (see FIG. 21 (c)) was used instead of the paper pattern 1.
　［実施例９］
　不織布Ａの代わりに、不織布Ｂ（エアスルー法で作製されたもの。オレフィンを主成分とし、厚み２．０ｍｍ。）を用いた以外は、実施例２と同様にして、吸水性シート（９）を得た。 [Example 9]
The water-absorbent sheet (9) was prepared in the same manner as in Example 2 except that the non-woven fabric B (produced by the air-through method. The main component was olefin and the thickness was 2.0 mm) was used instead of the non-woven fabric A. Obtained.
　［実施例１０］
　不織布Ａの代わりに、不織布Ｃ（エアスルー法で作製されたもの。オレフィンを主成分とし、厚み１．５ｍｍ。）を用いた以外は、実施例２と同様にして、吸水性シート（１０）を得た。 [Example 10]
The water-absorbent sheet (10) was prepared in the same manner as in Example 2 except that the non-woven fabric C (manufactured by the air-through method. The main component was olefin and the thickness was 1.5 mm) was used instead of the non-woven fabric A. Obtained.
　［比較例１］
縦１０ｃｍ、横４０ｃｍに切断した不織布Ａに、粒子状吸水剤（１）４．５ｇを均一に散布した。 [Comparative Example 1]
4.5 g of the particulate water absorbing agent (1) was uniformly sprayed on the non-woven fabric A cut into a length of 10 cm and a width of 40 cm.
　縦１０ｃｍ、横４０ｃｍの不織布Ｅ（第１の基材に相当する。）に、スチレンブタジエンゴムを含む接着剤（スプレーのり７７、スリーエムジャパン株式会社製）０．７～０．９ｇを均一に散布（散布量：１７．５～２１．５ｇ／ｍ）した後、不織布Ａの粒子状吸水剤（１）を散布した面と不織布Ｅの接着剤を散布した面が対合するように（接触するように）重ね、加圧圧着した。 0.7 to 0.9 g of an adhesive containing styrene-butadiene rubber (Spray Glue 77, manufactured by 3M Japan Ltd.) is uniformly sprayed on a non-woven fabric E (corresponding to the first base material) having a length of 10 cm and a width of 40 cm. (Spray amount: 17.5 to 21.5 g / m), the surface on which the particulate water absorbing agent (1) of the non-woven fabric A is sprayed and the surface on which the adhesive of the non-woven fabric E is sprayed face each other (contact). (Like) and pressure-bonded.
　粒子状吸水剤（１）と面していない側の不織布Ａの表面に、粒子状吸水剤（１）４．５ｇを均一に散布した。 4.5 g of the particulate water absorbent (1) was uniformly sprayed on the surface of the non-woven fabric A on the side not facing the particulate water absorbent (1).
　前記の不織布Ｅとは別に、縦１０ｃｍ、横４０ｃｍの不織布Ｅ（以下、不織布Ｅ２と称する。第２の基材に相当する。）に、前記の接着剤０．７～０．９ｇを均一に散布した後、不織布Ａの粒子状吸水剤（１）を散布した面と不織布Ｅ２の接着剤を散布した面が対合するように（接触するように）重ね、加圧圧着して中間体シートＺを得た。最後に、中間体シートＺを不織布Ｆで包み、加圧圧着することで、吸水性シート（１１）を得た。 Apart from the non-woven fabric E, 0.7 to 0.9 g of the adhesive is uniformly applied to the non-woven fabric E having a length of 10 cm and a width of 40 cm (hereinafter referred to as non-woven fabric E2, which corresponds to a second base material). After spraying, the surface on which the particulate water absorbing agent (1) of the non-woven fabric A is sprayed and the surface on which the adhesive of the non-woven fabric E2 is sprayed are overlapped so as to face each other (contact), and pressure-bonded to form an intermediate sheet. I got Z. Finally, the intermediate sheet Z was wrapped with the non-woven fabric F and pressure-bonded to obtain a water-absorbent sheet (11).
　［比較例２］
　型紙１を用いずに、粒子状吸水剤（１）を不織布Ａに均一に全面に散布した点を除いては、実施例１と同様にして、吸水性シート（１２）を得た。 [Comparative Example 2]
A water-absorbent sheet (12) was obtained in the same manner as in Example 1 except that the particulate water-absorbent agent (1) was uniformly sprayed on the entire surface of the non-woven fabric A without using the paper pattern 1.
　［比較例３］
　不織布Ａ２の代わりに不織布Ｅを用いた点を除いては、実施例１と同様にして、吸水性シート（１３）を得た。中間不織布については、不織布Ａを用いている。 [Comparative Example 3]
A water-absorbent sheet (13) was obtained in the same manner as in Example 1 except that the non-woven fabric E was used instead of the non-woven fabric A2. As the intermediate non-woven fabric, the non-woven fabric A is used.
　［比較例４］
　不織布Ａの代わりに不織布Ｅを用いた点を除いては、実施例２と同様にして、吸水性シート（１４）を得た。 [Comparative Example 4]
A water-absorbent sheet (14) was obtained in the same manner as in Example 2 except that the non-woven fabric E was used instead of the non-woven fabric A.
　なお、本実施例で使用した不織布Ａ～Ｃ、Ｇは、いずれも透水性シートであった。 The non-woven fabrics A to C and G used in this example were all water permeable sheets.
　〔不織布の物性の測定方法〕
　実施例１～１０および比較例１～４で用いた不織布Ａ～Ｃ、ＥおよびＧの伸び率、厚み、嵩密度、液拡散面積、不織布に対する粒子状吸水剤の透過率は、以下の方法に従って測定した。 [Measuring method of physical properties of non-woven fabric]
The elongation, thickness, bulk density, liquid diffusion area, and transmittance of the particulate water-absorbing agent for the nonwoven fabrics A to C, E, and G used in Examples 1 to 10 and Comparative Examples 1 to 4 are determined according to the following methods. It was measured.
　［伸び率の測定方法］
　伸び率測定用の不織布を長辺が１００ｍｍ、短辺が３０ｍｍの長方形に切り取った。このとき、長辺は不織布ロールの幅方向であり、短辺は不織布ロールの巻き取り長さ方向とする。なお、本実施例で吸水性シートに用いられる縦（短辺）１００ｍｍ、横（長辺）４００ｍｍのサイズの不織布は、縦（短辺）を不織布ロールの幅方向とし、横（長辺）を不織布ロールの巻き取り長さ方向としている。図２２（ａ）のように、切り取った伸び率測定用の不織布の両端から５ｍｍの位置に対し、それぞれ短辺と並行になるように目安線を引いた。目安線に重なるように、それぞれダブルクリップで挟んだ（図２２（ｂ））。ダブルクリップは、爪の長さが３０ｍｍ以上のものを用いた。一方のダブルクリップには錘を取りつけ、錘を取り付けたダブルクリップと錘を足した重さは１１０ｇとした。室温雰囲気下で、錘のついていないダブルクリップを持ち、もう一方のダブルクリップについた錘が空中に浮くように持ち上げ、不織布がダブルクリップと錘の重さで伸びた状態を２０秒維持した。その直後、空中に浮かせたまま不織布の長辺方向の長さを測定した（図２２（ｃ））。空中に浮かした後の長辺の長さと空中に浮かせる前の長辺の長さ１００ｍｍより、空中に浮かした後の長さがどの程度伸びているか、次の式を使用して比率を求め、伸び率とした。 [Measurement method of elongation rate]
The non-woven fabric for measuring the elongation was cut into a rectangle having a long side of 100 mm and a short side of 30 mm. At this time, the long side is in the width direction of the non-woven fabric roll, and the short side is in the winding length direction of the non-woven fabric roll. In the non-woven fabric having a length (short side) of 100 mm and a width (long side) of 400 mm used for the water-absorbent sheet in this embodiment, the length (short side) is the width direction of the non-woven fabric roll and the width (long side) is the width direction. The winding length direction of the non-woven fabric roll is used. As shown in FIG. 22A, reference lines were drawn at positions 5 mm from both ends of the cut non-woven fabric for measuring the elongation rate so as to be parallel to the short sides. Each was sandwiched between double clips so as to overlap the reference line (FIG. 22 (b)). The double clip used had a claw length of 30 mm or more. A weight was attached to one of the double clips, and the total weight of the double clip to which the weight was attached and the weight was 110 g. In a room temperature atmosphere, a double clip without a weight was held, and the weight attached to the other double clip was lifted so as to float in the air, and the non-woven fabric was kept stretched by the weight of the double clip and the weight for 20 seconds. Immediately after that, the length of the non-woven fabric in the long side direction was measured while floating in the air (FIG. 22 (c)). Calculate the ratio using the following formula to determine how much the length after floating in the air is longer than the length of the long side after floating in the air and the length of the long side before floating in the air of 100 mm. The growth rate was used.
Figure JPOXMLDOC01-appb-M000012
Figure JPOXMLDOC01-appb-M000012
　＜不織布の厚み測定＞
　ダイヤルシックネスゲージ　大型タイプ（厚み測定器）（株式会社　尾崎製作所製、型番：Ｊ－Ｂ、測定子：アンビル上下φ５０ｍｍ）を用いて測定した。測定点数は、異なる箇所を５回とし、測定値は５点の平均値とした。厚み測定時は、不織布に圧力が出来るだけかからないよう、ハンドルからゆっくりと手を離し、厚みを測定した。 <Measurement of non-woven fabric thickness>
Dial thickness gauge Measured using a large type (thickness measuring instrument) (manufactured by Ozaki Seisakusho Co., Ltd., model number: JB, stylus: anvil top and bottom φ50 mm). The number of measurement points was 5 times at different points, and the measured value was an average value of 5 points. When measuring the thickness, the thickness was measured by slowly releasing the hand from the handle so that pressure was not applied to the non-woven fabric as much as possible.
　＜不織布の嵩密度の計算方法＞
　縦を１０ｃｍ以上、横を４０ｃｍ以上のサイズに切り取った不織布の重量を測定した。不織布の縦と横の長さ、および＜厚み測定＞より測り取った厚みをそれぞれ掛けて不織布の体積を計算し、不織布の重量を不織布の体積で割って嵩密度を計算した。 <Calculation method of bulk density of non-woven fabric>
The weight of the non-woven fabric cut into a size of 10 cm or more in length and 40 cm or more in width was measured. The volume of the non-woven fabric was calculated by multiplying the vertical and horizontal lengths of the non-woven fabric and the thickness measured from <thickness measurement>, respectively, and the bulk density was calculated by dividing the weight of the non-woven fabric by the volume of the non-woven fabric.
　＜不織布の液拡散面積の測定方法＞
　目開きが２ｍｍ、線形が０．９ｍｍの網を用いた直径３０ｃｍの篩を平面上に置き、１０ｃｍ四方に切り取った不織布（第２の基材）を置いた。１ｍｌのシリンジに口径０．５０ｍｍの注射針を装着して、青色１号試薬を２０ｐｐｍ含む生理食塩水１．００ｇを量りとり、篩上の不織布の中央にシリンジの生理食塩水を垂直に注入した。この時、篩の網と平面は十分に離れており、不織布と網を通過した生理食塩水は網に接しないようにした。不織布が生理食塩水を吸水して液の拡散が完了すると、生理食塩水が拡散している面積を測定した。 <Measurement method of liquid diffusion area of non-woven fabric>
A sieve having a diameter of 30 cm using a net having a mesh size of 2 mm and an alignment of 0.9 mm was placed on a flat surface, and a non-woven fabric (second base material) cut into 10 cm squares was placed. An injection needle having a diameter of 0.50 mm was attached to a 1 ml syringe, 1.00 g of physiological saline containing 20 ppm of Blue No. 1 reagent was weighed, and the physiological saline of the syringe was vertically injected into the center of the non-woven fabric on the sieve. .. At this time, the mesh of the sieve and the flat surface were sufficiently separated from each other so that the non-woven fabric and the physiological saline passing through the mesh did not come into contact with the mesh. When the non-woven fabric absorbed the physiological saline and the diffusion of the liquid was completed, the area where the physiological saline was diffused was measured.
　＜不織布に対する粒子状吸水剤の透過率＞
　目開き８５０μｍのメッシュ３２を有するＪＩＳ標準篩（Ｔｈｅ　ＩＩＤＡ　ＴＥＳＴＩＮＧ　ＳＩＥＶＥ：内径８０ｍｍ；ＪＩＳ　Ｚ８８０１－１（２０００））、またはＪＩＳ標準篩に相当する篩３１の中に、直径８０ｍｍに切断した不織布（第１の基材１１）を図２３に示すように設置し、周囲をテープ３３でとめた（少なくとも直径７５ｍｍ以上は粒子が透過可能な面積を確保する）。不織布（第１の基材１１）は後述の方法により、吸水性シートから取り出したものを使用してもよい。篩３１の中の不織布（第１の基材１１）上（図２３の矢印の方向）から、粒子状吸水剤１４（重量平均粒子径：３６７μｍ、粒度分布：８５０μｍ～６００μｍが６．１％　６００μｍ～５００μｍが１４．５％　５００μｍ～３００μｍが５０％　３００μｍ～１５０μｍが２７．６％　１５０μｍ～４５μｍが１．９％　４５μｍ以下０．１％）１０．０ｇを投入し、ロータップ型ふるい振盪機（株式会社飯田製作所製ＥＳ－６５型ふるい振盪機；回転数２３０ｒｐｍ、衝撃数１３０ｒｐｍ）を用いて、室温（２０～２５℃）、相対湿度５０％ＲＨの条件下で５分間振盪した。振盪後、不織布（第１の基材１１）と上記ＪＩＳ標準篩に相当する篩３１のメッシュ３２を通過した粒子状吸水剤１４（すなわち、篩３１のメッシュ３２より下部分３１ａに存在する粒子状吸水剤１４）の質量（Ｗ（ｇ））を測定し、下記式（ｉ）にしたがって、粒子状吸水剤１４の透過率を算出した。なお、測定は２回行い、その平均値を算出した。 <Transmittance of particulate water absorbent to non-woven fabric>
A JIS standard sieve (The IIDA TESTING SIEVE: inner diameter 80 mm; JIS Z8801-1 (2000)) having a mesh 32 with an opening of 850 μm, or a non-woven fabric cut to a diameter of 80 mm in a sieve 31 corresponding to the JIS standard sieve (No. 1). The base material 11) of No. 1 was installed as shown in FIG. 23, and the periphery was fastened with a tape 33 (at least a diameter of 75 mm or more secures an area through which particles can permeate). As the non-woven fabric (first base material 11), one taken out from the water-absorbent sheet by the method described later may be used. From the top of the non-woven fabric (first base material 11) in the sieve 31 (in the direction of the arrow in FIG. 23), the particulate water absorbent 14 (weight average particle diameter: 367 μm, particle size distribution: 850 μm to 600 μm is 6.1% 600 μm). ~ 500 μm is 14.5% 500 μm ~ 300 μm is 50% 300 μm ~ 150 μm is 27.6% 150 μm ~ 45 μm is 1.9% 45 μm or less 0.1%) 10.0 g is added and a low tap type sieve shaker (stock) Using an ES-65 type sieve shaker manufactured by Iida Seisakusho Co., Ltd .; rotation speed 230 rpm, impact number 130 rpm), the particles were shaken for 5 minutes under the conditions of room temperature (20 to 25 ° C.) and relative humidity of 50% RH. After shaking, the particulate water absorbing agent 14 (that is, particles existing in the portion 31a below the mesh 32 of the sieve 31) has passed through the non-woven fabric (first base material 11) and the mesh 32 of the sieve 31 corresponding to the JIS standard sieve. The mass (W (g)) of the water absorbing agent 14) was measured, and the transmittance of the particulate water absorbing agent 14 was calculated according to the following formula (i). The measurement was performed twice, and the average value was calculated.
Figure JPOXMLDOC01-appb-M000013
Figure JPOXMLDOC01-appb-M000013
　なお、上記透過率の測定に用いた粒子状吸水剤は、重量平均粒子径３００～４５０μｍ、粒度分布８５０μｍ～１５０μｍである粒子状吸水剤を９０重量％以上含んでなる粒子状吸水剤である。よって、本実施例で算出された第１の基材に対する粒子状吸水剤の透過率は、第１の基材に対する特定の粒子状吸水剤の透過率にも相当する。 The particulate water absorbent used for measuring the transmittance is a particulate water absorbent containing 90% by weight or more of the particulate water absorbent having a weight average particle diameter of 300 to 450 μm and a particle size distribution of 850 μm to 150 μm. Therefore, the transmittance of the particulate water-absorbing agent for the first base material calculated in this example also corresponds to the transmittance of the specific particulate water-absorbing agent for the first base material.
　〔吸水性シートの評価方法〕
　＜吸水性シートからの粒子状吸水剤の取出し方法＞
　吸水性シートから上方不織布、および下方の不織布を剥がすことで粒子状吸水剤（中間不織布を含む場合は中間不織布と粒子状吸水剤と）を取り出した。上方および下方の不織布や中間不織布に貼着した粒子状吸水剤も全て取り出した。上方および下方の不織布を剥がす際には、吸水性シートを冷却し、不織布や粒子状吸水剤を貼着している接着剤（ホットメルト接着剤やスプレー糊）の接着性を十分に弱めた後に剥がした。この手順を踏むことで、不織布の繊維や構造厚みを変化させることなく取り出すことができ、正確に透過率を測定することが可能になる。吸水性シートの冷却方法は－１０℃以下の恒温槽に一定時間入れる、冷却スプレーを吹きかける、液体窒素をかける等、種々手段が考えられるが、不織布の繊維や構造、厚みを変化させることなく、かつ吸水性シートに含まれる粒子状吸水剤が吸湿しない条件で行うのであれば、特に限定されない。 [Evaluation method of water-absorbent sheet]
<Method of removing the particulate water-absorbing agent from the water-absorbing sheet>
By peeling the upper non-woven fabric and the lower non-woven fabric from the water-absorbent sheet, the particulate water-absorbing agent (in the case of containing the intermediate non-woven fabric, the intermediate non-woven fabric and the particulate water-absorbing agent) was taken out. All the particulate water absorbents attached to the upper and lower non-woven fabrics and the intermediate non-woven fabric were also taken out. When peeling off the upper and lower non-woven fabrics, cool the water-absorbent sheet to sufficiently weaken the adhesiveness of the adhesive (hot melt adhesive or spray glue) to which the non-woven fabric or particulate water-absorbing agent is attached. I peeled it off. By following this procedure, the fibers of the non-woven fabric and the structural thickness can be taken out without changing, and the transmittance can be measured accurately. Various means can be considered for cooling the water-absorbent sheet, such as putting it in a constant temperature bath at -10 ° C or lower for a certain period of time, spraying a cooling spray, or spraying liquid nitrogen, but without changing the fiber, structure, or thickness of the non-woven fabric. Moreover, it is not particularly limited as long as it is carried out under the condition that the particulate water absorbing agent contained in the water absorbing sheet does not absorb moisture.
　また、取出した粒子状吸水剤が吸湿している場合、例えば乾燥することで、含水率を１０質量％以下、好ましくは５±２質量％に調整して、上記透過率や本願で規定する諸物性を測定すればよい。含水率を調整するための乾燥条件としては、吸水性樹脂（粒子状吸水剤）の分解や変性が生じない条件ならば特に限定されないが、好ましくは減圧乾燥が良い。 When the extracted particulate water absorbing agent absorbs moisture, for example, by drying, the water content is adjusted to 10% by mass or less, preferably 5 ± 2% by mass, and the above-mentioned transmittance and various specifications specified in the present application. Physical properties may be measured. The drying conditions for adjusting the water content are not particularly limited as long as the water-absorbent resin (particulate water-absorbing agent) is not decomposed or modified, but vacuum drying is preferable.
　＜上方不織布中における粒子状吸水剤の含有割合の測定＞
　上方不織布を縦１０ｍｍ、横１０ｍｍの正方形に切り取ったもの（厚みはそのまま）を、株式会社島津製作所製マイクロフォーカスＸ線ＣＴシステム　ｉｎｓｐｅＸｉｏ　ＳＭＸ－１００ＣＴにより測定を行った。測定条件を以下に記す。 <Measurement of content ratio of particulate water absorbent in upper non-woven fabric>
A square piece of the upper non-woven fabric having a length of 10 mm and a width of 10 mm (with the same thickness) was measured by a microfocus X-ray CT system inspexio SMX-100CT manufactured by Shimadzu Corporation. The measurement conditions are described below.
　［Ｘ線ＣＴによる撮影］
　画像横サイズ（ｐｉｘｅｌ）：５１２
　画像縦サイズ（ｐｉｘｅｌ）：５１２
　Ｘ線管電圧（ｋＶ）：５０
　Ｘ線管電流（μＡ）：４０
　インチサイズ（ｉｎｃｈ）：４．０
　Ｘ線フィルタ：なし
　ＳＤＤ（Ｘ線源の焦点とＸ線検出器の距離）（ｍｍ）：７００
　ＳＲＤ（Ｘ線源の焦点と測定試料の回転中心の距離）（ｍｍ）：５５０
　走査モード　１：ＣＢＣＴ
　走査モード　２：ノーマル走査
　走査角度：フル走査
　ビュー数：２４００
　アベレージ数：５
　スムージング：ＹＺ
　スライス厚（ｍｍ）：０．１６６
　ＢＨＣデータ：なし
　精細モード：あり
　ＦＯＶ　ＸＹ（最大撮影領域　ＸＹ）（ｍｍ）：５０．３
　ＦＯＶ　Ｚ（最大撮影領域　Ｚ）（ｍｍ）：４０．０。 [Shooting by X-ray CT]
Image horizontal size (pixel): 512
Image vertical size (pixel): 512
X-ray tube voltage (kV): 50
X-ray tube current (μA): 40
Inch size (inch): 4.0
X-ray filter: None SDD (distance between the focal point of the X-ray source and the X-ray detector) (mm): 700
SRD (distance between the focal point of the X-ray source and the center of rotation of the measurement sample) (mm): 550
Scanning mode 1: CBCT
Scan mode 2: Normal scan Scan angle: Full scan Number of views: 2400
Average number: 5
Smoothing: YZ
Slice thickness (mm): 0.166
BHC data: None Fine mode: Yes FOV XY (maximum shooting area XY) (mm): 50.3
FOV Z (maximum field of view Z) (mm): 40.0.
　次に、Ｘ線ＣＴの撮影データを、三谷商事株式会社製解析ソフト　Ｗｉｎ　ＲＯＯＦを用いて、以下のような手順で解析を行った。 Next, the X-ray CT imaging data was analyzed by the following procedure using the analysis software WinROOF manufactured by Mitani Corporation.
　（１）Ｗｉｎ　ＲＯＯＦを開き、Ｘ線ＣＴにて保存した解析したい画像（Ｊｐｅｇ）を選択する。 (1) Open Win ROOF and select the image (Jpeg) you want to analyze saved by X-ray CT.
　（２）画面上から２値処理、自動２値化、モード法、しきい値（適宜調整する）、実行という流れでクリック（選択）する。 (2) Click (select) from the screen in the flow of binary processing, automatic binarization, mode method, threshold value (adjust appropriately), and execution.
　（３）多角形ＲＯＩを選択し、第１の基材（上方不織布）中の粒子状吸水剤を囲み、粒子状吸水剤面積を計算させる。 (3) Select a polygonal ROI, surround the particulate water absorbent in the first base material (upper non-woven fabric), and have the particle water absorbent area calculated.
　（４）（３）と同様にして、吸水性シート中における粒子状吸水剤の総面積を計算する。 In the same manner as in (4) and (3), the total area of the particulate water absorbing agent in the water absorbing sheet is calculated.
　計算結果から、第１の基材中の粒子状吸水剤の含有割合（％）を下式により計算した。 From the calculation result, the content ratio (%) of the particulate water absorbing agent in the first base material was calculated by the following formula.
　第１の基材中の粒子状吸水剤の含有割合（％）＝第１の基材中の粒子状吸水剤面積（Ｉ）／粒子状吸水剤総面積（ＩＩ）×１００
　すなわち、第１の基材中の粒子状吸水剤の含有割合は、粒子状吸水剤の総面積に対する面積％で表される。なお、第１の基材の液を直接的に吸収する吸液面（上方不織布の吸収する液が導入される側の面）上には、粒子状吸水剤は、存在しても数％未満であるため、存在していないとみなすことができる。なお、下記の実施例においては、第１の基材中の粒子状吸水剤の含有割合が、吸水性シート全体に含有される粒子状吸水剤に対して、５％以上であった。 Content ratio (%) of particulate water-absorbing agent in the first base material = particle-like water-absorbing agent area (I) in the first base material / total particle-like water-absorbing agent area (II) × 100
That is, the content ratio of the particulate water absorbing agent in the first base material is represented by the area% with respect to the total area of the particulate water absorbing agent. The particulate water absorbent is less than a few percent even if it is present on the liquid absorbing surface that directly absorbs the liquid of the first base material (the surface on the side where the liquid to be absorbed by the upper non-woven fabric is introduced). Therefore, it can be considered that it does not exist. In the following examples, the content ratio of the particulate water absorbing agent in the first base material was 5% or more with respect to the particulate water absorbing agent contained in the entire water absorbing sheet.
　〔吸水性シートの評価方法〕
　＜逆戻り量（特定戻り量評価）＞
　図２４に示されるように縦１０ｃｍ、横４０ｃｍに作製した吸水性シート１０を、縦１４ｃｍ、横４０ｃｍの液体不透過性シート２１で上部に開口部ができるように包んだ。液不透過性シート２１で包んだ吸水性シート１０を平面に置き、その上に液注入筒４１（図２５）を図２６に示されるように吸水性シート１０の中央に置いた。この状態で、流速７ｍｌ／秒で液投入が可能な漏斗４２を使用して液注入筒４１へ２３℃の０．９重量％塩化ナトリウム水溶液８０ｇを投入した（図２７）。なお、この場合、シート２２において、液不透過性シート２１から露出した吸水性シート１０に対して、液が投入されている。液を投入してから１０分後、予め重量を測定した濾紙４３（型式Ｎｏ．２、ＡＤＶＡＮＴＥＣ製；直径１１０ｍｍの円形のもの）２０枚を、シート２２の中央、すなわち、吸水性シート１０の中央に載せ、直径１００ｍｍの円形の錘４４（１２００ｇ）をさらに載せて、１分間保持した。１分後、錘４４を除去し、濾紙４３の重量増分から逆戻り量１回目（ｇ）を測定した。錘４４を除去してから１分後、同様の操作（液を投入→投入１０分後、濾紙４３および錘４４（１２００ｇ）を載せて、１分間保持→１分後保持→錘を除去、逆戻り量の測定）を繰り返し、逆戻り量２回目（ｇ）、逆戻り量３回目（ｇ）を測定した。測定した逆戻り量の１回目から３回目までの合計を表８、表１０に示した。 [Evaluation method of water-absorbent sheet]
<Reverse amount (specific return amount evaluation)>
As shown in FIG. 24, the water-absorbent sheet 10 produced in a length of 10 cm and a width of 40 cm was wrapped with a liquid-impermeable sheet 21 having a length of 14 cm and a width of 40 cm so as to have an opening at the top. The water-absorbent sheet 10 wrapped with the liquid-impermeable sheet 21 was placed on a flat surface, and the liquid injection cylinder 41 (FIG. 25) was placed on the water-absorbent sheet 10 in the center as shown in FIG. 26. In this state, 80 g of a 0.9 wt% sodium chloride aqueous solution at 23 ° C. was charged into the liquid injection cylinder 41 using a funnel 42 capable of charging the liquid at a flow velocity of 7 ml / sec (FIG. 27). In this case, in the sheet 22, the liquid is charged into the water-absorbent sheet 10 exposed from the liquid-impermeable sheet 21. Ten minutes after the liquid was added, 20 sheets of filter paper 43 (model No. 2, manufactured by ADVANTEC; circular one having a diameter of 110 mm) whose weight was measured in advance were placed in the center of the sheet 22, that is, the center of the water-absorbent sheet 10. A circular weight 44 (1200 g) having a diameter of 100 mm was further placed on the surface and held for 1 minute. After 1 minute, the weight 44 was removed, and the first reversion amount (g) was measured from the weight increment of the filter paper 43. 1 minute after removing the weight 44, the same operation (adding the liquid → 10 minutes after adding the liquid, placing the filter paper 43 and the weight 44 (1200 g), holding for 1 minute → holding after 1 minute → removing the weight, reversing (Measurement of amount) was repeated, and the second reversion amount (g) and the third reversion amount (g) were measured. Tables 8 and 10 show the total of the measured reversion amounts from the first to the third.
　＜厚み比（Ｌｂ／Ｌａ）の算出方法＞
　Ｌａは、間隙における上方不織布の吸液面（第１の基材の吸液面）から下方不織布（第２の基材）の吸水層側の表面までの厚みであり、Ｌｂは、粒子状吸水剤が含まれる領域における上方不織布の吸液面（第１の基材の吸液面）から下方不織布（第２の基材）の吸水層側の表面までの厚みである。 <Calculation method of thickness ratio (Lb / La)>
La is the thickness from the liquid absorbing surface of the upper nonwoven fabric (liquid absorbing surface of the first substrate) to the surface of the lower nonwoven fabric (second substrate) on the water absorbing layer side in the gap, and Lb is the particulate water absorption. It is the thickness from the liquid-absorbing surface of the upper non-woven fabric (the liquid-absorbing surface of the first base material) to the surface of the lower non-woven fabric (the second base material) on the water-absorbing layer side in the region containing the agent.
　［Ｘ線ＣＴによる吸水性シートの厚み測定］
　Ｘ線ＣＴ　による吸水性シートの撮影は、縦３５０ｍｍで横１００ｍｍで厚み３ｍｍのプラスチック板に、長さ１８０ｍｍに切り取った吸水性シートの両端をガムテープで固定し、Ｘ線装置（島津製作所製、ｉｎｓｐｅＸｉｏ　ＳＭＸ－１００ＣＴ）内部プレート上に前記プラスチック板を厚み方向と垂直に設置し、下記条件で吸水性シートの中央を測定することにより撮影した。 [Measurement of water-absorbent sheet thickness by X-ray CT]
The water-absorbent sheet was photographed by X-ray CT by fixing both ends of the water-absorbent sheet cut to a length of 180 mm to a plastic plate 350 mm long, 100 mm wide and 3 mm thick with gum tape, and then using an X-ray device (manufactured by Shimadzu Corporation, inspeXio). SMX-100CT) The plastic plate was placed on the inner plate perpendicular to the thickness direction, and the center of the water-absorbent sheet was measured under the following conditions.
　使用装置：ｉｎｓｐｅＸｉｏ　ＳＭＸ－１００ＣＴ（島津製作所製）
　Ｘ線管電圧（ｋＶ）　：８０
　Ｘ線管電流（μＡ）　：４０
　インチサイズ（ｉｎｃｈ）　：４．０
　Ｘ線フィルタ　：なし
　ＳＯＤ（ｍｍ）　：７００
　ＳＲＤ（ｍｍ）　：５５０
　ビュー数　：２４００
　アベレージ数　：５×１
　スライス厚（ｍｍ）　：０．１６６
　ＣＴ　モード１　：ＣＢＣＴ
　ＣＴ　モード２　：ノーマル操作
　走査角度　：フル走査
　ＢＨＣ　データ　：なし
　センターアジャスト：あり
　精細モード　：あり
　ＦＯＶ（　ＸＹ）（ｍｍ）　：５０．３
　ＦＯＶ　（Ｚ）（ｍｍ）　：２０．０
　ボクセルサイズ（ｍｍ／ｖｏｘｅｌ）：０．０９８
　撮影して得られた立体映像を長さ方向に２０３分割した断面図を取得し、５０枚目、１００枚目、１５０枚目の画像から、吸水性シートの厚みを測り取った。厚みを測り取るとき、上層不織布下の間隙における上方不織布の吸液面から下方不織布の吸水層側の表面までの厚みをＬａとし、上層不織布下の粒子状吸水剤が含まれる領域における上方不織布の吸液面から下方不織布の吸水層側の表面までの厚みをＬｂとした。 Equipment used: inspexio SMX-100CT (manufactured by Shimadzu Corporation)
X-ray tube voltage (kV): 80
X-ray tube current (μA): 40
Inch size (inch): 4.0
X-ray filter: None SOD (mm): 700
SRD (mm): 550
Number of views: 2400
Number of averages: 5 x 1
Slice thickness (mm): 0.166
CT mode 1: CBCT
CT mode 2: Normal operation Scanning angle: Full scanning BHC data: None Center adjust: Yes Fine mode: Yes FOV (XY) (mm): 50.3
FOV (Z) (mm): 20.0
Voxel size (mm / voxel): 0.098
A cross-sectional view obtained by dividing the stereoscopic image obtained by photographing into 203 in the length direction was acquired, and the thickness of the water-absorbent sheet was measured from the 50th, 100th, and 150th images. When measuring the thickness, the thickness from the liquid-absorbing surface of the upper non-woven fabric to the surface of the lower non-woven fabric on the water-absorbing layer side in the gap under the upper non-woven fabric is La, and the thickness of the upper non-woven fabric in the region under the upper non-woven fabric containing the particulate water-absorbing agent is defined as La. The thickness from the liquid absorbing surface to the surface of the lower nonwoven fabric on the water absorbing layer side was defined as Lb.
　＜保形性の評価＞
　吸水性シートに対し、＜逆戻り量＞を評価した後、吸水性シートの中央を幅方向に切断し、粒子状吸水剤が含まれない領域（すなわち、間隙）を目視で確認した。この時、間隙に存在するものを確認し、以下の評価基準で評価した。
評価基準
〇：粒子状吸水剤が含まれる領域が、間隙により隔てられている
（すなわち、間隙にはいかなる部材も存在しない、または、間隙には吸水層を矜持する基材（すなわち、単層形態の場合は、上層不織布および下方不織布；二層形態の場合は、上方不織布、中間不織布および下方不織布）が主に存在する）
×：間隙の存在割合が少なく、並列する粒子状吸水剤が含まれる領域同士が、つながっている（間隙により隔てられていない）
（すなわち、間隙とされていた領域に粒子状吸水剤が入り込んだり、吸水層を矜持する基材の存在割合が少なくなっている） <Evaluation of shape retention>
After evaluating the <reverse amount> with respect to the water-absorbent sheet, the center of the water-absorbent sheet was cut in the width direction, and the region (that is, the gap) containing no particulate water-absorbent was visually confirmed. At this time, what was present in the gap was confirmed and evaluated according to the following evaluation criteria.
Evaluation Criteria 〇: The region containing the particulate water-absorbing agent is separated by a gap (that is, there is no member in the gap, or the gap is a substrate having a water-absorbing layer (that is, a single-layer form). In the case of, the upper non-woven fabric and the lower non-woven fabric; in the case of the two-layer form, the upper non-woven fabric, the intermediate non-woven fabric and the lower non-woven fabric) are mainly present).
X: Regions containing a small amount of gaps and parallel particulate water absorbents are connected (not separated by gaps).
(That is, the particle-like water-absorbing agent has entered the region that was the gap, and the proportion of the base material that holds the water-absorbing layer has decreased.)
　下記表７～表１０に、実施例１～１０および比較例１～４で製造した吸水性シートの構成と、各吸水性シートで用いた基材の物性の評価結果、吸水性シートの評価結果を示す。なお、表７～表１０中、ＳＡＰとは、粒子状吸水剤を意味する。また、表７および表９におけるＳＡＰ配置領域（％）とは、上方不織布の面方向において、粒子状吸水剤が配置された基材の全面積に対する粒子状吸水剤が含まれる領域の面積割合であり、ＳＡＰ非配置領域（％）とは、上方不織布の面方向において、粒子状吸水剤が配置された基材の全面積に対する粒子状吸水剤が含まれない領域（すなわち、間隙）の面積割合を意味する。ここで、粒子状吸水剤が配置された基材とは、粒子状吸水剤を散布した基材を意味する。なお、本実施例では、上方不織布、中間不織布および下方不織布は同じサイズである。 Tables 7 to 10 below show the configurations of the water-absorbent sheets produced in Examples 1 to 10 and Comparative Examples 1 to 4, the evaluation results of the physical properties of the base material used in each water-absorbent sheet, and the evaluation results of the water-absorbent sheet. Is shown. In Tables 7 to 10, SAP means a particulate water absorbing agent. Further, the SAP arrangement region (%) in Tables 7 and 9 is the area ratio of the region containing the particulate water absorbent to the total area of the base material on which the particulate water absorbent is arranged in the plane direction of the upper non-woven fabric. The SAP non-arranged region (%) is the area ratio of the region (that is, the gap) not containing the particulate water-absorbing agent to the total area of the base material on which the particulate water-absorbing agent is arranged in the plane direction of the upper non-woven fabric. Means. Here, the base material on which the particulate water absorbing agent is arranged means a base material on which the particulate water absorbing agent is sprayed. In this embodiment, the upper non-woven fabric, the intermediate non-woven fabric, and the lower non-woven fabric have the same size.
Figure JPOXMLDOC01-appb-T000014
Figure JPOXMLDOC01-appb-T000014
Figure JPOXMLDOC01-appb-T000015
Figure JPOXMLDOC01-appb-T000015
Figure JPOXMLDOC01-appb-T000016
Figure JPOXMLDOC01-appb-T000016
Figure JPOXMLDOC01-appb-T000017
Figure JPOXMLDOC01-appb-T000017
　以上の結果より、実施例１～１０の吸水性シートは、比較例１～４の吸水性シートと比較して、保形性が高く、かつ、逆戻り量が顕著に少なかった。すなわち、単層形態および二層形態の吸水性シートにおいて、伸縮性を有する上方不織布を用いて、吸水層において間隙を設けることにより、逆戻り量を低減でき、保形性が高いことが確認できた。 From the above results, the water-absorbent sheets of Examples 1 to 10 had higher shape retention and a significantly smaller amount of reversion as compared with the water-absorbent sheets of Comparative Examples 1 to 4. That is, it was confirmed that in the single-layer and two-layer water-absorbent sheets, the amount of reversion can be reduced and the shape-retaining property is high by providing a gap in the water-absorbent layer by using an upper non-woven fabric having elasticity. ..
　また、本実施形態においては、二層形態は単層形態に比べて、逆戻り量が多くなる傾向にある。これは、二層形態の上層不織布に対する粒子状吸水剤の量（すなわち、上方不織布と中間不織布との間に位置する粒子状吸水剤の量）が、単層形態の上層不織布に対する粒子状吸水剤の量（すなわち、上方不織布と下方不織布との間に位置する粒子状吸水剤の量）よりも少ないことも要因のひとつでありうる。そのため、単層形態と二層形態との逆戻り量の低減効果の差は一概に比較することは難しいと考える。 Further, in the present embodiment, the amount of reversion tends to be larger in the two-layer form than in the single-layer form. This is because the amount of the particulate water-absorbing agent for the two-layered upper-layer non-woven fabric (that is, the amount of the particulate water-absorbing agent located between the upper nonwoven fabric and the intermediate nonwoven fabric) is the particulate water-absorbing agent for the single-layered upper-layer nonwoven fabric. (That is, the amount of the particulate water-absorbing agent located between the upper non-woven fabric and the lower non-woven fabric) may be one of the factors. Therefore, it is difficult to make a general comparison of the difference in the effect of reducing the amount of reversion between the single-layer form and the two-layer form.
　なお、本出願は、２０１９年１１月２８日に出願された日本特許出願第２０１９－２１５８８７号および２０１９年１１月２８日に出願された日本特許出願第２０１９－２１５８８８号に基づいており、その開示内容は、参照により全体として引用されている。 This application is based on Japanese Patent Application No. 2019-2158887 filed on November 28, 2019 and Japanese Patent Application No. 2019-215888 filed on November 28, 2019, and disclosure thereof. The content is cited as a whole by reference.
１０　　吸水性シート
１１、１１ａ　　第１の基材、
１１ｂ　　中間基材、
１２、１２ａ、１２ｂ　　吸水層、
１３　　第２の基材、
１４、１４ａ、１４ｂ　　粒子状吸水剤、
１５、１５ａ、１５ｂ　　間隙
１６　　ラッピングシート、
１８、１８ａ　　積層体、
１８ｂ　　構成体、
２０　　吸水性シート、
２１　　液体不透過シート、
３１　　篩、
３１ａ　篩のメッシュより下部分、
３２　　メッシュ、
３３　　テープ
４１　　液注入筒、
４２　　漏斗、
４３　　濾紙
４４　　錘、
４５　　液注入筒、
６０　　架台、
６１　　パイプ、
６３　　アクリル板、
６４　　漏斗、
６５　　金属製トレイ。 10 Water- absorbent sheet 11, 11a First base material,
11b Intermediate base material,
12, 12a, 12b water absorption layer,
13 Second base material,
14, 14a, 14b particulate water absorbent,
15, 15a, 15b gap 16 wrapping sheet,
18, 18a laminate,
18b construct,
20 water-absorbent sheet,
21 Liquid opaque sheet,
31 sieve,
31a Below the mesh of the sieve,
32 mesh,
33 Tape 41 Liquid injection tube,
42 funnel,
43 Filter paper 44 Weight,
45 liquid injection tube,
60 pedestals,
61 pipe,
63 Acrylic board,
64 funnel,
65 Metal tray.

Claims (43)

  1. 　第１の基材と、
    　第２の基材と、
    　前記第１の基材と、前記第２の基材との間に位置する吸水層と、
    を有する、吸水性シートであって、
    　前記吸水層が粒子状吸水剤を含み、
    　前記第１の基材の表面が、液を直接的に吸収する吸液面を形成し、
    　前記第２の基材の厚み（ｍｍ）に対する、前記第１の基材の厚み（ｍｍ）の比（第１の基材の厚み（ｍｍ）／第２の基材の厚み（ｍｍ））が、１．５以上１４未満である、吸水性シート。     With the first base material
    With the second base material,
    A water absorption layer located between the first base material and the second base material,
    It is a water-absorbent sheet having
    The water absorbing layer contains a particulate water absorbing agent and contains
    The surface of the first base material forms a liquid absorbing surface that directly absorbs the liquid.
    The ratio of the thickness (mm) of the first base material to the thickness (mm) of the second base material (thickness of the first base material (mm) / thickness of the second base material (mm)) , 1.5 or more and less than 14, water-absorbent sheet.
  2. 　前記第１の基材の嵩密度が、０．１ｇ／ｃｍ３以下である、請求項１に記載の吸水性シート。 The water-absorbent sheet according to claim 1, wherein the bulk density of the first base material is 0.1 g / cm 3 or less.
  3. 　前記第１の基材が、エアスルー不織布である、請求項１または２に記載の吸水性シート。 The water-absorbent sheet according to claim 1 or 2, wherein the first base material is an air-through non-woven fabric.
  4. 　少なくとも、前記第１の基材の表面に配置させるラッピングシートを有する、請求項１～３のいずれか１項に記載の吸水性シート。 The water-absorbent sheet according to any one of claims 1 to 3, which has at least a wrapping sheet to be arranged on the surface of the first base material.
  5. 　前記第１の基材が、前記粒子状吸水剤を含み、
    　前記第１の基材中の前記粒子状吸水剤の含有割合が、前記吸水性シート全体に含有される前記粒子状吸水剤に対して、５％以上である、請求項１～４のいずれか１項に記載の吸水性シート。     The first base material contains the particulate water absorbent and contains.
    Any of claims 1 to 4, wherein the content ratio of the particulate water absorbing agent in the first base material is 5% or more with respect to the particulate water absorbing agent contained in the entire water absorbing sheet. The water-absorbent sheet according to item 1.
  6. 　前記第２の基材の液拡散面積が、６０００ｍｍ２以上である、請求項１～５のいずれか１項に記載の吸水性シート。 The water-absorbent sheet according to any one of claims 1 to 5, wherein the liquid diffusion area of the second base material is 6000 mm 2 or more.
  7. 　前記第２の基材の液拡散面積が、７０００ｍｍ２以上である、請求項１～５のいずれか１項に記載の吸水性シート。 The water-absorbent sheet according to any one of claims 1 to 5, wherein the liquid diffusion area of the second base material is 7,000 mm 2 or more.
  8. 　前記第２の基材が、スパンレース不織布である、請求項１～７のいずれか１項に記載の吸水性シート。 The water-absorbent sheet according to any one of claims 1 to 7, wherein the second base material is a spunlace non-woven fabric.
  9. 　前記第１の基材の厚みは、０．７ｍｍ以上５ｍｍ以下である、請求項１～８のいずれか１項に記載の吸水性シート。 The water-absorbent sheet according to any one of claims 1 to 8, wherein the thickness of the first base material is 0.7 mm or more and 5 mm or less.
  10. 　前記第２の基材の厚みは、０．０５以上０．９ｍｍ以下である、請求項１～９のいずれか１項に記載の吸水性シート。 The water-absorbent sheet according to any one of claims 1 to 9, wherein the thickness of the second base material is 0.05 or more and 0.9 mm or less.
  11. 　前記第１の基材に対する粒子状吸水剤の透過率が４０質量％以上である、請求項１～１０のいずれか１項に記載の吸水性シート。 The water-absorbent sheet according to any one of claims 1 to 10, wherein the transmittance of the particulate water-absorbing agent with respect to the first base material is 40% by mass or more.
  12. 　前記粒子状吸水剤のＣＲＣが、３０ｇ／ｇ以上である、請求項１～１１のいずれか１項に記載の吸水性シート。 The water-absorbing sheet according to any one of claims 1 to 11, wherein the CRC of the particulate water-absorbing agent is 30 g / g or more.
  13. 　前記粒子状吸水剤のＣＲＣが、３３ｇ／ｇ以上である、請求項１～１１のいずれか１項に記載の吸水性シート。 The water-absorbing sheet according to any one of claims 1 to 11, wherein the CRC of the particulate water-absorbing agent is 33 g / g or more.
  14. 　前記粒子状吸水剤のＣＲＣが、３５ｇ／ｇ以上である、請求項１～１１のいずれか１項に記載の吸水性シート。 The water-absorbing sheet according to any one of claims 1 to 11, wherein the CRC of the particulate water-absorbing agent is 35 g / g or more.
  15. 　前記粒子状吸水剤のＡＡＰが２５ｇ／ｇ以上である、請求項１～１４のいずれか１項に記載の吸水性シート。 The water-absorbing sheet according to any one of claims 1 to 14, wherein the AAP of the particulate water-absorbing agent is 25 g / g or more.
  16. 　前記粒子状吸水剤の表面張力が、６０ｍＮ／ｍ以上である、請求項１～１５のいずれか１項に記載の吸水性シート。 The water-absorbing sheet according to any one of claims 1 to 15, wherein the surface tension of the particulate water-absorbing agent is 60 mN / m or more.
  17. 　前記吸水性シートが、接着剤を含み、
    　前記接着剤の使用量が、前記粒子状吸水剤の質量に対して、０．０５～２．０倍である、請求項１～１６のいずれか１項に記載の吸水性シート。     The water-absorbent sheet contains an adhesive and contains
    The water-absorbent sheet according to any one of claims 1 to 16, wherein the amount of the adhesive used is 0.05 to 2.0 times the mass of the particulate water-absorbing agent.
  18. 　前記吸水層において、前記粒子状吸水剤が含まれる領域が、実質的に粒子状吸水剤を含まない間隙を隔てて配置され、
    　前記第１の基材は、伸び率が１０％以上である、請求項１～１７のいずれか１項に記載の吸水性シート。     In the water-absorbing layer, regions containing the particulate water-absorbing agent are arranged with a gap substantially free of the particulate water-absorbing agent.
    The water-absorbent sheet according to any one of claims 1 to 17, wherein the first base material has an elongation rate of 10% or more.
  19. 　前記第１の基材の目付量は、１０～６０ｇ／ｍ２である、請求項１～１８のいずれか１項に記載の吸水性シート。 The water-absorbent sheet according to any one of claims 1 to 18, wherein the basis weight of the first base material is 10 to 60 g / m 2.
  20. 　前記間隙における前記第１の基材の前記吸液面から前記第２の基材の前記吸水層側の表面までの厚み（Ｌａ）に対する、前記粒子状吸水剤が含まれる領域における前記第１の基材の前記吸液面から前記第２の基材の前記吸水層側の表面までの厚み（Ｌｂ）の比（Ｌｂ／Ｌａ）が、１．０５以下である、請求項１８または１９に記載の吸水性シート。 The first in the region containing the particulate water-absorbing agent with respect to the thickness (La) of the first base material from the liquid-absorbing surface of the first base material to the surface of the second base material on the water-absorbing layer side in the gap. 18. The ratio (Lb / La) of the thickness (Lb) from the liquid absorbing surface of the base material to the surface of the second base material on the water absorbing layer side is 1.05 or less, according to claim 18 or 19. Water-absorbent sheet.
  21. 　前記粒子状吸水剤が含まれる領域および前記間隙は、前記第１の基材の前記吸液面における一の方向に沿って伸びた形状を有し、並列して配置されている、請求項１８～２０のいずれか１項に記載の吸水性シート。 18. The region containing the particulate water absorbing agent and the gap have a shape extending along one direction on the liquid absorbing surface of the first base material and are arranged in parallel. The water-absorbent sheet according to any one of 20 to 20.
  22. 　前記第１の基材の前記吸水層側の面が起毛されている、請求項１～１７のいずれか１項に記載の吸水性シート。 The water-absorbent sheet according to any one of claims 1 to 17, wherein the surface of the first base material on the water-absorbent layer side is raised.
  23. 　前記起毛されている面の起毛面積測定試験における起毛面積率が５％以上である、請求項２２に記載の吸水性シート。 The water-absorbent sheet according to claim 22, wherein the raised area ratio in the raised area measurement test of the raised surface is 5% or more.
  24. 　前記第１の基材は、接着剤によって前記粒子状吸水剤を担持しない、請求項２２または２３に記載の吸水性シート。 The water-absorbing sheet according to claim 22 or 23, wherein the first base material does not support the particulate water-absorbing agent by an adhesive.
  25. 　前記粒子状吸水剤の含有量が、２００ｇ／ｍ２以上である、請求項２２～２４のいずれか１項に記載の吸水性シート。 The water-absorbing sheet according to any one of claims 22 to 24, wherein the content of the particulate water-absorbing agent is 200 g / m 2 or more.
  26. 　第２の基材上の接着剤がホットメルト接着剤である、請求項２２～２５のいずれか１項に記載の吸水性シート。 The water-absorbent sheet according to any one of claims 22 to 25, wherein the adhesive on the second base material is a hot melt adhesive.
  27. 　前記粒子状吸水剤のＧＰＲが、２０ｇ／ｍｉｎ以上である、請求項２２～２６のいずれか１項に記載の吸水性シート。 The water-absorbing sheet according to any one of claims 22 to 26, wherein the GPR of the particulate water-absorbing agent is 20 g / min or more.
  28. 　請求項１～２７のいずれか１項に記載の吸水性シートを液体透過性シートと、液体不透過性シートとで挟持することによりなり、前記液体透過性シートが、前記第１の基材側に位置し、前記液体不透過性シートが、前記第２の基材側に位置している、吸収性物品。 The water-absorbent sheet according to any one of claims 1 to 27 is sandwiched between a liquid permeable sheet and a liquid permeable sheet, and the liquid permeable sheet is on the first base material side. An absorbent article in which the liquid impermeable sheet is located on the side of the second substrate.
  29. 　第１の基材と、
    　第２の基材と、
    　前記第１の基材と、前記第２の基材との間に位置する吸水層と、
    を有する、吸水性シートであって、
    　前記吸水層は、粒子状吸水剤を含み、前記粒子状吸水剤が含まれる領域が、実質的に前記粒子状吸水剤を含まない間隙を隔てて配置され、
    　前記第１の基材の表面は、液を直接的に吸収する吸液面を形成し、
    　前記第１の基材は、伸び率が１０％以上である、吸水性シート。     With the first base material
    With the second base material,
    A water absorption layer located between the first base material and the second base material,
    It is a water-absorbent sheet having
    The water-absorbing layer contains the particulate water-absorbing agent, and the region containing the particulate water-absorbing agent is arranged with a gap substantially free of the particulate water-absorbing agent.
    The surface of the first base material forms a liquid absorbing surface that directly absorbs the liquid.
    The first base material is a water-absorbent sheet having an elongation rate of 10% or more.
  30. 　前記第１の基材の目付量は、１０～６０ｇ／ｍ２である、請求項２９に記載の吸水性シート。 The water-absorbent sheet according to claim 29, wherein the basis weight of the first base material is 10 to 60 g / m 2.
  31. 　前記第１の基材の嵩密度が、０．１ｇ／ｃｍ３以下である、請求項２９または３０に記載の吸水性シート。 The water-absorbent sheet according to claim 29 or 30, wherein the bulk density of the first base material is 0.1 g / cm 3 or less.
  32. 　前記第１の基材が、エアスルー不織布である、請求項２９～３１のいずれか１項に記載の吸水性シート。 The water-absorbent sheet according to any one of claims 29 to 31, wherein the first base material is an air-through non-woven fabric.
  33. 　前記吸水層Ａの上に前記第１の基材を積層した積層体と、吸水層Ｂの上に中間基材を積層した構成体と、が、前記第２の基材の上に、積層されてなる、請求項２９～３２のいずれか１項に記載の吸水性シート。 A laminate in which the first base material is laminated on the water absorption layer A and a structure in which an intermediate base material is laminated on the water absorption layer B are laminated on the second base material. The water-absorbent sheet according to any one of claims 29 to 32.
  34. 　前記吸水層の上に前記第１の基材を積層した積層体のみが、前記第２の基材の上に、積層されてなる、請求項２９～３３のいずれか１項に記載の吸水性シート。 The water absorption according to any one of claims 29 to 33, wherein only the laminate in which the first base material is laminated on the water absorption layer is laminated on the second base material. Sheet.
  35. 　前記間隙における前記第１の基材の前記吸液面から前記第２の基材の前記吸水層側の表面までの厚み（Ｌａ）に対する、前記粒子状吸水剤が含まれる領域における前記第１の基材の前記吸液面から前記第２の基材の前記吸水層側の表面までの厚み（Ｌｂ）の比（Ｌｂ／Ｌａ）が、１．０５以下である、請求項３４に記載の吸水性シート。 The first in the region containing the particulate water-absorbing agent with respect to the thickness (La) of the first base material from the liquid-absorbing surface of the first base material to the surface of the second base material on the water-absorbing layer side in the gap. The water absorption according to claim 34, wherein the ratio (Lb / La) of the thickness (Lb) from the liquid absorption surface of the base material to the surface of the second base material on the water absorption layer side is 1.05 or less. Sex sheet.
  36. 　前記第２の基材が、スパンレース不織布である、請求項２９～３５のいずれか１項に記載の吸水性シート。 The water-absorbent sheet according to any one of claims 29 to 35, wherein the second base material is a spunlace non-woven fabric.
  37. 　前記第１の基材が、前記粒子状吸水剤を含み、前記第１の基材中の前記粒子状吸水剤の含有割合が、前記吸水性シート全体に含有される前記粒子状吸水剤に対して、５％以上である、請求項２９～３６のいずれか１項に記載の吸水性シート。 The first base material contains the particulate water absorbing agent, and the content ratio of the particulate water absorbing agent in the first base material is relative to the particulate water absorbing agent contained in the entire water absorbing sheet. The water-absorbent sheet according to any one of claims 29 to 36, which is 5% or more.
  38. 　前記第１の基材に対する前記粒子状吸水剤の透過率が４０質量％以上である、請求項２９～３７のいずれか１項に記載の吸水性シート。 The water-absorbent sheet according to any one of claims 29 to 37, wherein the transmittance of the particulate water-absorbing agent with respect to the first base material is 40% by mass or more.
  39. 　前記粒子状吸水剤が含まれる領域および前記間隙は、前記第１の基材の前記吸液面における一の方向に沿って伸びた形状を有し、並列して配置されている、請求項２９～３８のいずれか１項に記載の吸水性シート。 29. The region containing the particulate water absorbing agent and the gap have a shape extending along one direction on the liquid absorbing surface of the first base material and are arranged in parallel. The water-absorbent sheet according to any one of 38 to 38.
  40. 　少なくとも、前記第１の基材の表面に配置させるラッピングシートを有する、請求項２９～３９のいずれか１項に記載の吸水性シート。 The water-absorbent sheet according to any one of claims 29 to 39, which has at least a wrapping sheet to be arranged on the surface of the first base material.
  41. 　前記粒子状吸水剤のＣＲＣが３０ｇ／ｇ以上である、請求項２９～４０のいずれか１項に記載の吸水性シート。 The water-absorbing sheet according to any one of claims 29 to 40, wherein the CRC of the particulate water-absorbing agent is 30 g / g or more.
  42. 　前記吸水性シートが、接着剤を含み、
    前記接着剤の使用量が、前記粒子状吸水剤の質量に対して、０．０５～２．０倍である、請求項２９～４１のいずれか１項に記載の吸水性シート。     The water-absorbent sheet contains an adhesive and contains
    The water-absorbent sheet according to any one of claims 29 to 41, wherein the amount of the adhesive used is 0.05 to 2.0 times the mass of the particulate water-absorbing agent.
  43. 　請求項２９～４２のいずれか１項に記載の吸水性シートを液体透過性シートと、液体不透過性シートとで挟持することによりなり、前記液体透過性シートが、前記第１の基材側に位置し、前記液体不透過性シートが、前記第２の基材側に位置している、吸収性物品。 The water-absorbent sheet according to any one of claims 29 to 42 is sandwiched between the liquid permeable sheet and the liquid permeable sheet, and the liquid permeable sheet is on the first base material side. An absorbent article in which the liquid impermeable sheet is located on the side of the second substrate.
PCT/JP2020/044517 2019-11-28 2020-11-30 Water-absorbent sheet and absorbent article including same WO2021107159A1 (en)

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