CN114748248A - Absorbent article - Google Patents

Absorbent article Download PDF

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Publication number
CN114748248A
CN114748248A CN202210275862.XA CN202210275862A CN114748248A CN 114748248 A CN114748248 A CN 114748248A CN 202210275862 A CN202210275862 A CN 202210275862A CN 114748248 A CN114748248 A CN 114748248A
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CN
China
Prior art keywords
sheet
core
absorbent
liquid
covering sheet
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
CN202210275862.XA
Other languages
Chinese (zh)
Other versions
CN114748248B (en
Inventor
大坪俊文
时田规弘
渡部芳久
田村竜也
野田祐树
加藤伸亨
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Unicharm Corp
Original Assignee
Unicharm Corp
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from JP2018125328A external-priority patent/JP6838015B2/en
Priority claimed from JP2018125327A external-priority patent/JP6838014B2/en
Priority claimed from JP2018125325A external-priority patent/JP6838013B2/en
Priority claimed from JP2018125326A external-priority patent/JP6839135B2/en
Application filed by Unicharm Corp filed Critical Unicharm Corp
Publication of CN114748248A publication Critical patent/CN114748248A/en
Application granted granted Critical
Publication of CN114748248B publication Critical patent/CN114748248B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

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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
    • A61F13/51—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 outer layers
    • A61F13/511—Topsheet, i.e. the permeable cover or layer facing the skin
    • A61F13/51121—Topsheet, i.e. the permeable cover or layer facing the skin characterised by the material
    • A—HUMAN NECESSITIES
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    • A61F13/00—Bandages or dressings; Absorbent pads
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    • A61F13/42—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators with wetness indicator or alarm
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    • 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
    • A61F2013/530343—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 being natural 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
    • 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
    • A61F2013/5349—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 being a tissue-wrapped core
    • 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
    • A61F13/537—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 characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer
    • A61F2013/53765—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 characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer characterized by its geometry
    • A61F2013/53778—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 characterised by a layer facilitating or inhibiting flow in one direction or plane, e.g. a wicking layer characterized by its geometry with grooves
    • 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
    • A61F13/84—Accessories, not otherwise provided for, for absorbent pads
    • A61F13/8405—Additives, e.g. for odour, disinfectant or pH control
    • A61F2013/8408—Additives, e.g. for odour, disinfectant or pH control with odour control

Landscapes

  • Health & Medical Sciences (AREA)
  • General Health & Medical Sciences (AREA)
  • Epidemiology (AREA)
  • Engineering & Computer Science (AREA)
  • Veterinary Medicine (AREA)
  • Public Health (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Animal Behavior & Ethology (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Vascular Medicine (AREA)
  • Biomedical Technology (AREA)
  • Hematology (AREA)
  • Chemical & Material Sciences (AREA)
  • Materials Engineering (AREA)
  • Dermatology (AREA)
  • Absorbent Articles And Supports Therefor (AREA)

Abstract

The invention provides an absorbent article which can reduce chemical substances used by the absorbent article as much as possible and prevent third parties from mistaking excretion. A disposable diaper (101) as an absorbent article comprises a liquid-permeable front sheet (131) positioned on the skin-facing surface side, a liquid-impermeable back sheet positioned on the non-skin-facing surface side, and an absorbent body (120) positioned between the front sheet and the back sheet (132). The absorbent body comprises a liquid-absorbent core (121) and a core covering sheet (122) covering the liquid-absorbent core. The core covering sheet has a 1 st core covering sheet (122a) covering at least a part of the skin-facing surface side of the liquid-absorbent core and containing 1 st pulp fibers, and a 2 nd core covering sheet (122b) covering at least a part of the non-skin-facing surface side of the liquid-absorbent core and containing 2 nd pulp fibers. The kappa number of the 2 nd pulp fiber is smaller than that of the 1 st pulp fiber.

Description

Absorbent article
The present application is a divisional application of an application having an application number of 201980043799.3(PCT/JP2019/025912) with an application date of 2019.6.28, and an invention name of "absorbent article".
Technical Field
The present invention relates to an absorbent article, and more particularly to an absorbent article such as a light incontinence pad, a panty liner, a sanitary napkin, a textile absorbent pad, a urine absorbent pad, and a disposable diaper for adults and children.
Background
Conventionally, it has been known that paper such as tissue paper is used without bleaching. For example, patent document 1 discloses a case where tissue paper or the like is used without bleaching.
Documents of the prior art
Patent document
Patent document 1: japanese Kokai publication 2011-505505
Patent document 2: japanese patent laid-open publication No. 2016-120192
Patent document 3: japanese patent laid-open No. 56-53745
Disclosure of Invention
Problems to be solved by the invention
(problem of the invention 1)
However, in recent years, with regard to absorbent articles such as diapers, users or caregivers have been increasingly conscious of health, and there has been an increasing desire to use safer articles and an increasing desire to use natural materials such as organic materials.
Therefore, it is considered to use unbleached tissue paper for the core covering sheet covering the liquid-absorbent core in the diaper.
However, when unbleached tissue paper is used for the diaper, the tissue paper is light brown and has a color similar to urine, and therefore, it may be difficult for a third person who performs nursing or the like to know urination, and there is a possibility that the diaper is changed in consideration of urination although urination is not performed.
Therefore, an object of the invention 1 of the present application is to provide an absorbent article that can reduce the amount of chemicals used in the absorbent article as much as possible and that prevents third parties from mistaking for excretion.
(problem of invention 2)
Conventionally, there has been known a disposable sanitary napkin in which a colored deodorizing sheet is disposed between an absorbent core and a non-skin side sheet. For example, patent document 2 discloses a case where a deodorizing sheet is formed of a deodorizing agent-containing sheet using granular activated carbon as a deodorizing agent and two covering sheets covering the front and back surfaces of the sheet.
In the invention disclosed in patent document 2, since the deodorizing sheet is disposed between the absorbent core and the non-skin side sheet, the color of the deodorizing sheet is hardly visually recognized when the sanitary napkin is viewed from the skin-facing surface, and the color of the deodorizing sheet cannot be effectively utilized.
In recent years, development of an absorbent article such as a sanitary napkin has been desired from the viewpoint of being capable of being used with confidence.
Therefore, an object of the invention 2 of the present application is to provide an absorbent article capable of reducing the chemical substances used in the absorbent article as much as possible and effectively utilizing the color used therein.
(problems of the invention 3 and the invention 4)
Conventionally, there has been known an absorbent article including a liquid-permeable front sheet, a liquid-impermeable back sheet, and an absorbent body interposed between the front sheet and the back sheet. For example, patent document 3 discloses an absorbent article including an absorbent body containing wood pulp fibers that have not been delignified.
In the absorbent article disclosed in patent document 3, the wood pulp fibers contained in the absorbent body are not delignified, and therefore the wood pulp fibers have a natural color tone derived from natural wood, and when the absorbent body is seen through the topsheet, the wearer can be given the impression that the natural intention of using natural materials is high.
However, while the cellulose component among the various components such as cellulose, hemicellulose and lignin mainly contained in wood or non-wood pulp is highly hydrophilic, lignin is less hydrophilic and may be said to be hydrophobic. Therefore, in the case where the pulp fibers that have not been subjected to the delignification treatment have a high hydrophobicity and the pulp fibers are distributed over the entire absorbent body, it is not possible to absorb and hold the body fluid by sucking the body fluid from the surface of the absorbent body into the inside.
The problems of the invention 3 and the invention 4 are to improve the conventional invention and to provide an absorbent article having an absorbent body which has a natural color tone inherent in wood and can sufficiently absorb and hold body fluid.
Means for solving the problems
(solution of invention 1)
The present invention relates to an absorbent article including a liquid-permeable top sheet positioned on a skin-facing surface side, a liquid-impermeable back sheet positioned on a non-skin-facing surface side, and an absorbent body positioned between the top sheet and the back sheet.
The absorbent article of claim 1 is characterized in that the absorbent body comprises a liquid-absorbent core and a core-covering sheet covering the liquid-absorbent core, the core-covering sheet has a 1 st core-covering sheet covering at least a part of a skin-facing surface side of the liquid-absorbent core and containing 1 st pulp fibers and a 2 nd core-covering sheet covering at least a part of a non-skin-facing surface side of the liquid-absorbent core and containing 2 nd pulp fibers, and the kappa number of the 2 nd pulp fibers is smaller than the kappa number of the 1 st pulp fibers.
In the absorbent article, the kappa number of the 1 st pulp fiber is 8 to 40, and the difference between the kappa number of the 2 nd pulp fiber and the kappa number of the 1 st pulp fiber is 2.4 or more. Therefore, the 1 st pulp fiber of the 1 st core covering sheet has a relatively large lignin content, and therefore chemical substances can be further reduced.
In the absorbent article, the difference between the kappa number of the 2 nd pulp fiber and the kappa number of the 1 st pulp fiber is 7.2 or more. Therefore, the skin-facing surface of the absorbent body can be colored by a color tone derived from wood, and an impression of a highly natural product using natural materials can be given.
In the absorbent article, the 1 st core covering sheet has both side edge portions between the non-skin-facing surface of the liquid-absorbent core and the 2 nd core covering sheet. Therefore, the area of the 1 st core covering sheet that can be visually recognized from the skin-facing surface can be reduced as much as possible, and the white area can be enlarged, so that the user can be given an impression of a clean article.
The absorbent article has a transverse direction and a longitudinal direction, and the sum of the transverse dimensions of both side edge portions of the 1 st core covering sheet is less than 1/3 of the transverse dimension of the liquid-absorbent core. Therefore, the 2 nd core covering sheet can be visually recognized from the non-skin-facing surface, and the presence or absence of urination can be prevented from being erroneously recognized.
In the absorbent article, the 1 st core covering sheet is superposed in the thickness direction on the outer side in the transverse direction of both side edges of the liquid-absorbent core. Therefore, the brown color of the side edges of the liquid-absorbent core can be made darker, and the user can recognize the position of the liquid-absorbent core.
The absorbent article has a transverse direction and a longitudinal direction, both side edges of the 1 st core covering sheet and both side edges of the 2 nd core covering sheet extend outward in the transverse direction from both side edges of the liquid-absorbent core, and the 1 st core covering sheet and the 2 nd core covering sheet are joined to each other outside in the transverse direction from both side edges of the liquid-absorbent core. Therefore, the visually recognizable area of the 1 st core covering sheet viewed from the skin-facing surface side can be enlarged as much as possible to make the portion having a color tone derived from wood large, and an impression of an article having a high natural intention using a natural material can be given.
In the absorbent article, the length dimension of the joint portion between the 1 st core covering sheet and the 2 nd core covering sheet is 50mm or less. Therefore, the use of an adhesive such as a hot-melt adhesive can be reduced as much as possible, and the waste of materials can be suppressed.
In the absorbent article, the indication section indicating the presence or absence of excrement from the outside of the back sheet is positioned on the non-skin-facing surface side of the liquid-absorbent core, and the indication section and the 2 nd core covering sheet are superposed in the thickness direction. Since the 2 nd core covering sheet around the indicator portion is white, it is possible to prevent erroneous recognition of the presence or absence of urination.
In the absorbent article, the separate member is located between the surface sheet and the 1 st core covering sheet. Therefore, the user can grasp the position of the independent member by the 1 st core covering sheet.
In the absorbent article, the top sheet has projections and recesses each extending in the longitudinal direction and alternately arranged in the lateral direction, and the recesses are in contact with the absorbent body while the projections are separated from the absorbent body. Therefore, the brown color of the 1 st core covering sheet can be reduced for the convex portion, and the user can be given an impression of a sanitary article.
In the absorbent article, the liquid-absorbent core has a narrow region of the liquid-absorbent core in the longitudinal center thereof, the narrow region being smaller in the lateral direction, and the back sheet has a colored portion in a region overlapping the narrow region. Therefore, the portion of the 1 st core covering sheet outside the narrow width region can be prevented from being visually recognized from the non-skin-facing surface side, and the impression that the article is a clean article can be given to the user.
(solution of invention 2)
The invention 2 relates to an absorbent article including a liquid-permeable top sheet positioned on a skin-facing surface side, a liquid-impermeable back sheet positioned on a non-skin-facing surface side, and an absorbent body positioned between the top sheet and the back sheet.
The absorbent article is characterized in that the absorbent body has a liquid-absorbent core and a core-covering sheet covering at least the skin-facing surface side of the liquid-absorbent core, and the material constituting the absorbent body contains a lignin component, and when the absorbent body is observed through the topsheet, the L value, the a value, and the b value of the Lab color system satisfy all conditions of 0.5. ltoreq. a value.ltoreq.10.0, 7. ltoreq. b value.ltoreq.15, and 70. ltoreq. L value.ltoreq.90.
In the absorbent article, when standard menstrual blood is dripped into the liquid-absorbent core through the topsheet, the difference in the a-value between the Lab color system and the b-value is 50 or less in the menstrual blood-absorbing region and the menstrual blood-non-absorbing region as viewed from the skin-facing surface side, and 20 or less in the b-value. Therefore, the difference between the a value and the b value can be made small, and the unpleasant feeling when the user or the caregiver observes the absorbent article after use can be suppressed.
In an absorbent article, the core covering sheet has a 1 st covering portion covering at least the skin-facing surface side of the liquid-absorbent core, the 1 st covering portion and the topsheet are bonded to each other with an adhesive, the content of the lignin component in the core covering sheet is higher than the content of the lignin component in the liquid-absorbent core, and the absorbent article has a plurality of concave portions extending continuously from the topsheet to a part of the liquid-absorbent core in the thickness direction. Therefore, it is possible to retain excreta such as menstrual blood and urine in the concave portions, and the surface area of the liquid-absorbent core that indirectly contacts menstrual blood through the topsheet and the core-covering sheet is large, and it is possible to quickly absorb and retain excreta in the liquid-absorbent core through the topsheet and the backsheet.
In the absorbent article, the concave portion has a bottom, and the surface sheet, the core covering sheet, and the liquid-absorbent core are partially compressed in the concave portion, and the density of the bottom of the concave portion is higher than that of the peripheral region of the concave portion. Therefore, the excrement accumulated in the concave portions can be quickly absorbed into the liquid-absorbent core, and can be absorbed and retained.
In the absorbent article, the concave portion is a through hole penetrating the topsheet and the absorbent body in the thickness direction. Therefore, since the liquid-impermeable back sheet is positioned at the bottom of the concave portion, the excrement accumulated in the concave portion can be absorbed and retained in the liquid-absorbent core from the peripheral surface portion of the concave portion without leaking to the non-skin-facing surface side of the absorbent body.
(solution of invention 3)
The invention 3 relates to an absorbent article including a liquid-permeable front sheet located on a skin-facing surface side, a liquid-impermeable back sheet located on a non-skin-facing surface side, and an absorbent body located between the front sheet and the back sheet.
The absorbent article of claim 3 is characterized in that the absorbent body has a liquid-absorbent core and a core covering sheet covering at least the skin-facing surface side of the liquid-absorbent core, the core covering sheet has a plurality of high lignin regions in a 1 st covering portion covering the skin-facing surface side of the liquid-absorbent core, the high lignin regions have a higher content of lignin component than in peripheral regions and are located at dispersed positions in a plan view, and the content of lignin component in the core covering sheet is higher than the content of lignin component in the liquid-absorbent core.
The absorbent article of claim 3 includes the following features.
(1) The core covering sheet has a lignin content of 0.2 to 10%.
(2) The core covering sheet has a wrinkling rate of 7-20% and a formation index of 50-300.
(3) The core cover sheet contains wood or non-wood pulp fibers, and the liquid-absorbent core contains cellulose fibers.
(4) The liquid-absorbent core contains particles having odor-absorbing properties.
(5) The absorber has a plurality of concave portions that are concave from the skin-facing surface side toward the non-skin-facing surface side.
(6) The core covering sheet further has a 2 nd covering portion covering the non-skin-facing surface side of the liquid-absorbent core, and the plurality of high lignin regions are located in the 2 nd covering portion.
(7) The surface sheet contains cotton fibers and the corestock water absorption of the core cover sheet is higher than the corestock water absorption of the surface sheet.
(8) The surface sheet has a 1 st portion and a 2 nd portion having a higher fiber density than the 1 st portion, the 1 st portion being joined to the high lignin region, and the 2 nd portion being joined to the low lignin region.
(9) The surface sheet has a multilayer structure, and the layer on the skin-facing surface side is mainly composed of cotton fibers.
(10) The surface sheet has a klemm water absorption that is lower than the core cover sheet.
(solution of invention 4)
The 4 th aspect of the present invention relates to an absorbent article including a liquid-permeable top sheet located on a skin-facing surface side, a liquid-impermeable back sheet located on a non-skin-facing surface side, and an absorbent body located between the top sheet and the back sheet.
An absorbent article according to claim 4 is characterized in that the absorbent body has a liquid-absorbent core and a core covering sheet covering at least the skin-facing surface side of the liquid-absorbent core, the core covering sheet has a 1 st covering portion covering the skin-facing surface side of the liquid-absorbent core, the 1 st covering portion and the topsheet are joined to each other with an adhesive, the core covering sheet has a higher content of lignin components than the liquid-absorbent core, and the absorbent article has a plurality of concave portions continuously extending at least from the topsheet to a part of the liquid-absorbent core in the thickness direction.
The absorbent article of claim 4 includes the following features.
(1) The core covering sheet further includes a 2 nd covering portion covering the non-skin-facing surface side of the liquid-absorbent core, and the 2 nd covering portion and the back surface sheet are bonded to each other with an adhesive.
(2) The concave portions have bottoms, the surface sheet, the core covering sheet, and the liquid-absorbent core are partially compressed in the concave portions, and thin portions of the concave portions have a higher density than thick portions where the concave portions are not present.
(3) The concave portion is an opening penetrating the topsheet and the absorbent body in the thickness direction.
(4) The adhesive is an SIS hot melt adhesive.
(5) The core covering sheet has a plurality of high lignin regions having a higher lignin content than the peripheral region and being located at dispersed positions in a plan view.
(6) The core cover sheet has a crepe ratio of 7-20% and a formation index of 50-300.
(7) The surface sheet has a 1 st portion and a 2 nd portion having a higher fiber density than the 1 st portion, the 1 st portion being joined to the high lignin region, and the 2 nd portion being joined to the peripheral region.
(8) The surface sheet has a multilayer structure, and the layer on the skin-facing surface side is mainly composed of cotton fibers.
(10) The surface sheet has a klemm water absorption that is lower than the core cover sheet.
ADVANTAGEOUS EFFECTS OF INVENTION
With the absorbent article of the invention 1, the kappa number of the pulp fiber 2 of the 2 nd core-covering sheet 122b is smaller than the kappa number of the pulp fiber of the 1 st core-covering sheet, and the 1 st core-covering sheet contains a large amount of unbleached pulp fiber. Thus, since the unbleached pulp fiber is less in the use of chemicals, an absorbent article with reduced use of chemicals can be provided. Further, since the 2 nd core covering sheet located on the non-skin-facing surface side is white with a small kappa number, the possibility of misidentifying the presence or absence of excretion can be reduced.
In the disposable absorbent article of claim 2, the absorbent body has a liquid-absorbent core and a core covering sheet covering at least the skin-facing surface side of the liquid-absorbent core, and the material constituting the absorbent body contains a lignin component. Therefore, an absorbent article can be provided in which unbleached pulp fibers are used for the absorbent body and the use of chemicals is reduced. When the absorbent is observed through the top sheet, the L value, the a value and the b value of the Lab color system satisfy all the conditions of 0.5. ltoreq. a value.ltoreq.50.0, 7. ltoreq. b value.ltoreq.15, and 70. ltoreq. L value.ltoreq.90. When the constituent material contains a lignin component, the lignin component causes the absorbent to be light brown in color. When excreta such as menstrual blood or urine is excreted into an absorbent article having an absorbent body that is light brown, and the absorbent body absorbs and retains the excreta, the redness of menstrual blood or the yellowness of urine is suppressed. Therefore, the user or the caregiver can be prevented from feeling unpleasant when viewing the used absorbent article. Thus, an absorbent article that effectively utilizes the color used in the absorber can be provided.
In at least one aspect of the absorbent article according to claim 3, the color tone derived from wood can be imparted to the absorbent body, thereby giving the impression of a product that is mild to the skin using natural materials, and the absorbent body can achieve appropriate adhesiveness to the top sheet and liquid absorption properties.
In at least one embodiment of the absorbent article according to claim 4, the core covering sheet contains a relatively large amount of lignin component and thus has a natural color tone derived from a natural material such as wood, and has a plurality of concave portions continuously extending from the topsheet in the thickness direction to a part of the liquid-absorbent core, so that body fluid can be rapidly absorbed and retained.
Drawings
The drawings show specific embodiments of the invention 1 to 4, and include not only the indispensable structure of the invention but also alternative and preferred embodiments.
Fig. 1 is a perspective view of a disposable diaper shown as an example of the absorbent article of the invention 1.
Fig. 2 is a partially cross-sectional developed plan view of the diaper in a state where the side seams are peeled off and stretched in the longitudinal and transverse directions, as viewed from the skin-facing surface.
Fig. 3 is a sectional view taken along line III-III of fig. 2.
Fig. 4 is a plan view of the absorber.
Fig. 5 (a) is a partially enlarged view of the region surrounded by the line v (a) of fig. 4. Fig. 5 (b) is a partially enlarged view of the region surrounded by the line v (b) of fig. 4.
Fig. 6 is a partially cross-sectional developed top view of the diaper of embodiment 2 of the 1 st invention similar to fig. 2.
Fig. 7 is a perspective view of the surface sheet.
Fig. 8 is a sectional view taken along line VIII-VIII of fig. 6.
Fig. 9 is the same partially sectional developed top view as fig. 2 of the diaper of embodiment 3.
Fig. 10 is a cross-sectional view taken along line X-X of fig. 9.
Fig. 11 is the same partially sectional developed top view as fig. 2 of the diaper of embodiment 2.
Fig. 12 is a plan view of a sanitary napkin shown as an example of the absorbent article of the invention 1.
Fig. 13 is a plan view of the sanitary napkin according to embodiment 1 shown as an example of the absorbent article of the invention 2 as viewed from the front side.
Fig. 14 is a plan view of the absorber as viewed from the back side.
Fig. 15 is a sectional view taken along line XV-XV of fig. 13.
Fig. 16 is a plan view of the absorber.
Fig. 17 is a partially enlarged view of the area surrounded by the XVII line of fig. 16.
Fig. 18 is a partially enlarged view of the area surrounded by the one-dot chain line XVIII-XVIII of fig. 15.
Fig. 19 is a plan view of a sanitary napkin according to embodiment 2 of the present invention 2.
Fig. 20 (a) is a line sectional view of xx (a) -xx (a) in fig. 19. Fig. 20 (b) is a cross-sectional view similar to fig. 20 (a) showing an example of a modification of the absorber according to embodiment 2.
Fig. 21 is a plan view of the absorbent article according to embodiment 3 of claim 2.
Fig. 22 is a plan view of the sanitary napkin according to embodiment 1 shown as an example of the absorbent article of the invention 3, as viewed from the front side.
Fig. 23 is a plan view of the absorber as viewed from the back side.
Fig. 24 is a sectional view taken along line XXIV-XXIV of fig. 22.
Fig. 25 is a plan view of the absorber.
Fig. 26 is a partially enlarged view of the area surrounded by the line XXVI of fig. 25.
Fig. 27 is a partially enlarged view of a region surrounded by a one-dot chain line XXVII-XXVII of fig. 24.
Fig. 28 is a plan view of the sanitary napkin according to embodiment 2 of claim 3.
Fig. 29 (a) is a sectional view of xxix (a) -xxix (a) of fig. 28. Fig. 29 (b) is a cross-sectional view similar to fig. 29 (a) showing an example of a modification of the absorbent body according to embodiment 2 of the 3 rd invention.
Fig. 30 is a plan view of the absorbent article according to embodiment 3 of claim 3.
Fig. 31 is a plan view of the sanitary napkin according to embodiment 1 of the absorbent article of the 4 th embodiment as viewed from the front surface side.
Fig. 32 is a plan view of the sanitary napkin as viewed from the back side.
Fig. 33 is a plan view of the absorber.
Fig. 34 is a cross-sectional view taken along line XXXIV of fig. 33.
Fig. 35 is a cross-sectional view similar to fig. 34 of an example of a modification of the absorber.
Fig. 36 is a plan view of an absorbent body of a sanitary napkin according to embodiment 2 of the 4 th invention.
Fig. 37 is a partial enlarged view of the region surrounded by XXXVII lines of fig. 36.
Fig. 38 is a sectional view of the sanitary napkin according to embodiment 2 of the present invention 4, similar to fig. 34.
Fig. 39 is a plan view of the absorbent article according to embodiment 3 of the 4 th invention.
Description of the reference numerals
101. Disposable diapers (absorbent articles); 121. a liquid absorbent core; 121d, narrow width area; 122a, 1 st core covering sheet (core covering sheet); 122c, both side edge portions; 122d, both side edge portions; 122b, 2 nd core cover sheet (core cover sheet); 122e, both side edge portions; 122f, both side edge portions; 127. a joint portion; 131. a surface sheet; 131a, a surface sheet; 132. a back sheet; 139. an intermediate sheet (independent member); 141. bleaching pulp fibers; 142. unbleached pulp fiber; 161. a convex portion; 162. a recess; 171. an indicating section; 180. disposable sanitary napkins (absorbent articles); l1, length dimension of joint; w1, the lateral dimension of one of the two side edge portions; w2, the transverse dimension of the other of the two side edge portions; w4, transverse dimension of the absorber; x, transverse direction; y, longitudinal direction; z, thickness direction; 210. sanitary napkins (absorbent articles); 211. a surface sheet; 212. a back sheet; 220. an absorbent body; 221. a liquid absorbent core; 222. a core covering sheet; 225. 1 st cladding part; 226. a 2 nd cladding part; 240. pulp fibers; 241. bleaching pulp fibers; 242. unbleached pulp fiber; 251. a low lignin region; 252. a high lignin region; 260. a concave portion; 280. disposable diapers (absorbent articles); 310. sanitary napkins (absorbent articles); 311. a surface sheet; 312. a back sheet; 320. an absorbent body; 321. a liquid absorbent core; 322. a core covering sheet; 325. a 1 st cladding part; 326. a 2 nd cladding part; 340. pulp fibers; 341. bleaching pulp fibers; 342. unbleached pulp fiber; 351. a low lignin region; 352. a high lignin region; 360. a concave portion; 380. disposable diapers (absorbent articles); 402. the skin-facing surface; 403. a non-skin-facing surface; 410. sanitary napkins (absorbent articles); 411. a surface sheet; 412. a back sheet; 420. an absorbent body; 421. a liquid absorbent core; 422. a core covering sheet; 425. 1 st cladding part; 426. a 2 nd cladding part; 440. pulp fibers; 441. bleaching pulp fibers; 442. unbleached pulp fiber; 451. a low lignin region; 452. a high lignin region; 460. a concave portion; 460a, 1 st concave portion; 460b, a 2 nd concave portion; 460c, a 3 rd concave portion; 480. disposable diapers (absorbent articles).
Detailed Description
< invention 1 >
The following embodiments relate to the disposable absorbent article shown in the drawings, and include not only the indispensable structure of the invention but also alternative and preferable structures.
< embodiment 1 of the invention 1 >
A disposable diaper 101 as an example of the absorbent article of the present invention is described below with reference to the drawings. The disposable diaper 101 has a transverse direction X, a longitudinal direction Y, and a thickness direction Z intersecting (orthogonal to) each other.
Referring to fig. 1 to 3, a disposable diaper 101 includes a longitudinal center line bisecting its dimension in the width direction and a transverse center line bisecting its dimension in the longitudinal direction, a skin-facing surface (inner surface) and a non-skin-facing surface on the opposite side thereof, a ring-shaped elastic waist pad 102 extending in the waist-circumferential direction, an absorbent main body 103 attached to the skin-facing surface side of the elastic waist pad 102, a front waist region 104, a rear waist region 105, and a crotch region 106 located between the front waist region 104 and the rear waist region 105.
The elastic waist pad 102 has an elastic belt function of stretching in the girth direction, and includes a front waist pad 107 forming the front waist region 104 and a rear waist pad 108 forming the rear waist region 105.
The front waist pad 107 has a substantially trapezoidal shape defined by an inner end edge 107a, an outer end edge 107b, 1 st both side edges (both side edges of the front waist region) 107c, 107d extending from the outer end edge 107b to the inside in the longitudinal direction Y, and 2 nd both side edges 107e, 107f extending obliquely from the 1 st both side edges 107c, 107d to the inside in the longitudinal direction Y.
The back waist pad 108 has a substantially trapezoidal shape defined by an inner end edge 108a, an outer end edge 108b, 1 st both side edges (both side edges of the back waist region 105) 108c, 108d extending from the outer end edge 108b to the inside in the longitudinal direction Y, and 2 nd both side edges 108e, 108f extending obliquely from the 1 st both side edges 108c, 108d to the inside in the longitudinal direction Y.
The 1 st side edges 107c, 107d of the front waist panel 107 and the 1 st side edges 108c, 108d of the back waist panel 108 which face each other are overlapped with each other, and they are joined by side seams 109 which are intermittently arranged in the longitudinal direction Y (for example, joined by hot embossing or various heat welding means by sound waves or the like), thereby defining a waist opening 110 and a pair of leg openings 111.
The front waist pad 107 and the back waist pad 108 each include inner layer sheets (inner sheet) 112, 113 on the skin-facing surface side and outer layer sheets (outer sheet) 114, 115 on the non-skin-facing surface side. The inner sheets 112 and 113 and the outer sheets 114 and 115 can be used in an amount of 10g/m in basis weight 2～30g/m2SMS (spunbond/meltblown/spunbond) fiber nonwoven fabric, spunbond fiber nonwoven fabric, hot air fiber nonwoven fabric, plastic sheet, apertured plastic sheet, and laminate of the above materials.
A plurality of single-strand or multi-strand front waist elastic bodies (elastic members) 116 and rear waist elastic bodies (elastic members) 117 are respectively disposed between the inner sheet 112 and the outer sheet 114 of the front waist pad 107 and between the inner sheet 113 and the outer sheet 115 of the rear waist pad 108 so as to be stretchable in the transverse direction X, and the front waist pad 107 and the rear waist pad 108 are elasticized at least in the transverse direction X.
The front waist elastic body 116 and the rear waist elastic body 117 are partially cut or removed at the center portion of the front waist region 104 overlapping the absorbent main body 103 and at the center portion of the rear waist region 105 overlapping the absorbent main body 103, respectively, to define a front non-stretchable region 118 and a rear non-stretchable region 119. In this way, since the front non-stretchable region 118 and the rear non-stretchable region 119 are positioned at the center of the front waist region 104 and the center of the rear waist region 105, the contraction force of the front waist elastic body 116 and the contraction force of the rear waist elastic body 117 do not directly act on the center portion (the center portion of the liquid-absorbent core) of the portion of the main absorbent body 103 positioned on the inner surface of the front waist pad 107 and the inner surface of the rear waist pad 108, and gathers and the like are not formed, and therefore, the lowering of the absorption performance due to the application of the contraction force can be suppressed.
As the front waist elastic body 116 and the rear waist elastic body 117, for example, a single-strand or multi-strand elastic material having a fineness of 470dtex to 1240dtex and arranged in a state of being stretched 1.5 times to 3.5 times can be used. Conditions such as fineness and elongation of the front waist elastic body 116 and the rear waist elastic body 117, and a separation dimension (pitch) between the elastic bodies can be appropriately changed.
The inner sheet 112 and the outer sheet 114 of the front waist region 104 and the inner sheet 113 and the outer sheet 115 of the rear waist region 105 are not coated with a hot melt adhesive on their inner surfaces, and are joined to each other only by the hot melt adhesive coated on the front waist elastic body 116 and the rear waist elastic body 117 except for the joined portions formed by the side seams 109. The hot melt adhesive may be applied to the portions facing the inner sheets 112 and 113 and the outer sheets 114 and 115 over the entire circumferences of the front waist elastic member 116 and the rear waist elastic member 117.
Referring to fig. 2 and 3, the absorbent main body 103 includes a liquid-permeable top sheet 131 positioned on the skin-facing surface side, a liquid-impermeable back sheet 132 positioned on the non-skin-facing surface side, and an absorbent body 120 having liquid absorption properties, which is positioned between the two sheets 131 and 132 and has a narrow central portion in the longitudinal direction Y. The topsheet 131 and the absorbent body 120 are joined to each other by a known joining means such as a hot melt adhesive to form the liquid absorbent layer 130. Further, a liquid impermeable leakage prevention sheet 136 preferably having air permeability is disposed between the absorbent body 120 and the back sheet 132, thereby suppressing leakage of excrement such as urine. The dimension in the transverse direction X and the dimension in the longitudinal direction Y of the leakage-preventive sheet 136 are larger than the dimension in the transverse direction X and the dimension in the longitudinal direction Y of the liquid-absorbent core 121, and the leakage-preventive sheet 136 covers the entire area of the non-skin-facing surface of the liquid-absorbent core 121.
The back sheet 132 has side portions 134 located outward in the lateral direction X from both side edges of the absorbent body 120. The side portions 134 are bent toward the skin-facing side along a bending line 135 extending in the longitudinal direction Y, and have: both end fixing portions 133 fixed to the surface sheet 131 and separated from each other in the longitudinal direction Y; proximal edge portions 137 fixed to both side edge portions of the surface sheet 131 and located outside in the transverse direction X; and a distal edge portion (free edge portion) 138 extending in the longitudinal direction Y between the both-end fixing portions 133 and parallel to the proximal edge portion 137.
The distal edge 138 is formed in a sleeve shape in which an outer edge of the back sheet 132 in the lateral direction X is bent and fixed, and the single-strand or multi-strand rib elastic body 128 extending in the longitudinal direction Y is fixed to the back sheet 132 in a contractible state in an extended state. By contracting the cuff elastic body 128, the distal edge portion 138 is separated from the surface sheet 131, and the distal edge portion 138 comes into contact with the wearer's thighs to form a leakage prevention cuff, which prevents leakage of excrement. The leg elastic members 129 in a single strand or multiple strands extending in the longitudinal direction Y are fixed to the back sheet 132 in an extensible state outside the rib top elastic members 128 in the lateral direction X in both side portions 134 of the back sheet 132 so as to be contractible. By contracting the leg elastic members 129, the side portions 134 of the back sheet 132 come into contact with the thighs of the wearer.
The surface sheet 131 may be made of various liquid-permeable fibrous nonwoven fabrics, for example, having a basis weight of about 15g/m2～45g/m2The nonwoven fabric of air-through fibers, the porous plastic film, the laminate of the above materials, and the like. The back sheet 132 may be formed of a liquid-impermeable and moisture-permeable plastic film, a liquid-impermeable fibrous nonwoven fabric, a laminate of the above materials, or the like.
Referring to fig. 3 and 4, the absorbent body 120 includes a liquid-absorbent core 121 formed by mixing superabsorbent polymer particles (SAP) and cellulose fibers such as fluffed wood pulp and rayon fibers and shaped into a predetermined shape, and a liquid-permeable core covering sheet 122 for covering the entire liquid-absorbent core 121 to improve shape retention and liquid diffusion properties of the absorbent body 120.
The liquid-absorbent core 121 has wide regions 121c located at both ends in the longitudinal direction Y and having a constant dimension in the transverse direction X, and narrow regions 121d located at the center in the longitudinal direction Y and having a smaller dimension in the transverse direction X than the wide regions. When the diaper 101 is worn, the narrow regions 121d are located at the base of the legs, and the legs can be prevented from hitting the side edges 121a and 121b of the liquid-absorbent core 121 having a high rigidity when the legs move. Although not shown, the back sheet 132 has a colored portion in a region overlapping the narrow width region 121d, and thus the portion of the 1 st core covering sheet 122a outside the narrow width region 121d can be prevented from being visually recognized from the non-skin-facing surface side, which can give the impression of a clean article to the user.
The core covering sheet has a 1 st core covering sheet 122a located on the skin-facing surface side of the liquid-absorbent core 121 and containing the 1 st pulp fiber, and a 2 nd core covering sheet 122b located on the non-skin-facing surface side of the liquid-absorbent core 121 and containing the 2 nd pulp fiber.
The 1 st core covering sheet 122a and the 2 nd core covering sheet 122b have a dimension in the transverse direction X larger than the dimension in the transverse direction X of the liquid-absorbent core, and wrap the entire liquid-absorbent core 121. The 1 st core covering sheet and the 2 nd core covering sheet are laminated so as to be in contact with each other outside the liquid-absorbent core 121 in the transverse direction X, and are joined to each other at the contact portion by a known joining means such as a hot melt adhesive.
The 1 st core covering sheet 122a and the 2 nd core covering sheet 122b are formed of various well-known fiber nonwoven fabrics or tissue papers, mainly formed of pulp fibers. The 1 st core covering sheet 122a contains a large amount of unbleached pulp fibers (1 st pulp fibers) 142 that have not been subjected to delignification treatment. The 2 nd core covering sheet 122b contains a large amount of bleached pulp fibers (2 nd pulp fibers) 141 subjected to delignification treatment. The pulp fiber contains, in addition to wood pulp fiber obtained from coniferous or broadleaf trees as a raw material, non-wood pulp fiber obtained from cotton linters, manila hemp, kenaf, straw, bamboo, and banana as a raw material.
The pulp fiber is generally bleached pulp fiber 141 obtained by subjecting a raw material chip to a raw material chip treatment step, then to a cooking step (step 1 of delignification treatment) of adding a chemical to the raw material chip and boiling the chip at high temperature and high pressure to cook lignin, a screening step of removing foreign matters in the pulp, an oxygen exposure step of decomposing lignin remaining in the cooking step with oxygen (step 2 of delignification treatment), and a bleaching step of bleaching the pulp with a plurality of chemicals. The unbleached pulp fibers 142 are obtained by passing through only the cooking step and the screening step, which are, for example, the 1 st stage of the delignification treatment, among the above-described steps, and are obtained by performing the delignification treatment to a certain extent. The unbleached pulp fiber 142 of the invention has a lignin content of 0.2-10.0%.
The lignin content of the unbleached pulp fibers 142 and the bleached pulp fibers 141 was measured by the following method.
< method for measuring Lignin content >
Quantification of ADF
Reagent: an acid detergent solution (Hexadecyltrimethylammonium Bromide Bromide)10g was dissolved in 500mL of 1N sulfuric acid to obtain a chemical >
Acetone (II)
Decalin as an antifoaming agent (alternative)
< measurement procedure >
A sample (300 g) was weighed, placed in a 50mL Erlenmeyer flask, and 30mL of an acidic detergent solution was added. The flask was covered with aluminum foil, and the flask was placed in boiling water to decompose the product for 60 minutes. After the decomposition, it was transferred to a glass fiber filter paper (GA-200) -laid Gu's crucible and subjected to suction filtration, and the residue was washed with hot water and acetone. After air drying, thermal drying is carried out. The ash obtained by removing ash by taking a constant amount after drying is ADF, but ash obtained by quantifying lignin cannot be used for this purpose.
Lignin quantification
Reagent: 72% sulfuric acid
< measurement procedure >
A few drops of 72% sulfuric acid were dropped into the above-described dry gouge crucible to wet the whole, and then about twice the amount of ADF was added, and the sulfuric acid was appropriately added every hour and left for 3 to 4 hours. Thereafter, the reaction mixture was subjected to suction filtration and washed with hot water until the furnace liquid showed no acidity. After air drying, heat drying was carried out and a constant amount was taken. Ashing was performed at 550 ℃ in a Gu-Shi crucible to determine ash content.
Referring to fig. 5 a and 5 b, the 1 st core covering sheet 122a has a low lignin region (low lignin content region) 151 having a relatively low lignin content and a high lignin region (high lignin content region) 152 having a relatively high lignin content compared to the low lignin region 151. The low lignin regions 151 are formed primarily by the aggregation of bleached pulp fibers 141 and the high lignin regions 152 are formed primarily by the aggregation of unbleached pulp fibers 142. In a plan view of core-covering sheet 1 a, low-lignin regions 151 are peripheral regions located in a relatively large area on the outer surface of core-covering sheet 1 a, while high-lignin regions 152 are disposed so as to be scattered in low-lignin regions 151. Further, since the arrangement is such that the 1 st core covering sheet 122a has a sea-island structure in which the low lignin region 151 is a sea and the high lignin region 152 is an island. Further, the 2 nd core covering sheet 122b is formed of, for example, only bleached pulp fibers 141.
Since the 1 st core covering sheet 122a contains a large amount of unbleached pulp fibers 142, it has a light brown color as a whole derived from a plant material such as wood. Since the 2 nd core covering sheet 122b does not contain the unbleached pulp fiber 142 but contains only the bleached pulp fiber 141, it has a white color. In addition, since the other sheets 131 and 132 except for the 1 st core covering sheet 122a and the 2 nd core covering sheet 122b have a white color as a whole by mixing a white pigment such as titanium dioxide with the constituent fibers, the 1 st core covering sheet 122a can be easily visually recognized through the other sheets 131 and 132 when the inner surface of the diaper 101 is observed. On the other hand, since the 2 nd core covering sheet 122b has a white color as a whole, it is difficult to visually recognize it separately from the other sheets 131, 132 when the outer surface of the diaper 101 is observed.
The 1 st core covering sheet 122a is formed by interlacing a mixture of bleached pulp fibers 141 and unbleached pulp fibers 142 in a sheet-like manner in a papermaking process thereof, and since the bleached pulp fibers 141 are mainly arranged in the low-lignin region 151 and the unbleached pulp fibers 142 are mainly arranged in the high-lignin region 152, the boundary between the two regions 151 and 152 is not clear, and thus cannot be clearly distinguished. Further, as a method for forming the high lignin regions 152 dispersedly in the low lignin regions 151 in the entire outer surface of the 1 st core covering sheet 122a, for example, a mixing method of the pulp fibers 141 and 142, a mixing ratio, a conveying speed of a conveyor at the time of production, a nozzle diameter at the time of depositing the pulp fibers on the conveyor by air ejected from a plurality of nozzles, an air volume of the blown air, an air velocity, and the like may be appropriately adjusted.
Since the two regions 151 and 152 are formed by adjusting various conditions of the production process, the unbleached pulp fibers 142 may be contained in part of the low lignin region 151, and the bleached pulp fibers 141 may be contained in the high lignin region 152. Thus, the low lignin region 151 and the high lignin region 152 are not formed by only the bleached pulp fibers 141 and the unbleached pulp fibers 142, respectively.
The high lignin region 152 is a region having a higher content of lignin component than the low lignin region 151 which is a peripheral region of the 1 st core covering sheet 122a, and therefore the high lignin region 152 can be formed without using a sheet in which the bleached pulp fibers 141 and the unbleached pulp fibers 142 are mixed. For example, the high lignin region 152 having a higher lignin content than the surrounding region can be formed by allowing a liquid containing the lignin component to dispersedly infiltrate into a fibrous nonwoven fabric sheet composed of rayon fibers or synthetic fibers.
Since core-covering sheet 1 a has a plurality of high-lignin regions 152 mainly composed of unbleached pulp fibers 142, it has a light brown color (wood color) derived from a plant material in a surface view, as compared with core-covering sheet 2b composed of only bleached pulp fibers 141, and can give an impression to a wearer or a wearer assistant that it is a product using a natural material which is mild to the skin. Further, since the 1 st core covering sheet 122a has a light brown color, the yellow color of urine (excrement) is suppressed when the excreted urine is absorbed and held by the absorbent body 120 through the surface sheet 131. This makes it possible to suppress the aversion to the urine caused by the direct visual recognition of the color of the urine. Further, since the lignin component has an antibacterial action, the propagation of mixed bacteria after use can be suppressed and the disposal can be performed hygienically.
The bleached pulp fibers 141 and unbleached pulp fibers 142 have different kappa numbers because they have different lignin contents. The unbleached pulp fiber 142 had a higher kappa number because of its higher lignin content, and the bleached pulp fiber 141 had a lower kappa number because of its lower lignin content. Thus, comparing the two, the kappa number of the bleached pulp fiber 141 was less than the kappa number of the unbleached pulp fiber 142. The kappa number of the bleached pulp fiber 141 is 1-2. The kappa number of the unbleached pulp fiber 142 is8 to 40. The kappa number was measured according to JIS 8211.
With this diaper 101, the kappa number of bleached pulp fibers 141 in core 2-coversheet 122b is less than the kappa number of unbleached pulp fibers 142 in core 1-coversheet 122a, and core 1-coversheet 122a contains a significant amount of unbleached pulp fibers 142. Thus, since the unbleached pulp fibers 142 use less chemicals, an absorbent article with reduced use of chemicals can be provided. Further, the pulp fiber of the 2 nd core covering sheet 122b located on the non-skin-facing surface side has a small kappa number and is white, so that the possibility of misrecognizing the presence or absence of excretion can be reduced.
In the present invention, the kappa number K of the pulp fiber of the sheet is determined by calculating the kappa number K1 of the unbleached pulp fiber 142 per unit weight and the kappa number K2 of the bleached pulp fiber 141 per unit weight, and the sum of the kappa numbers (i.e., K1+ K2) is defined as the kappa number of the pulp fiber of the sheet. Sheet a in the uppermost column of table 1 means that when a sheet is formed under the conditions that the proportion of unbleached pulp fibers 142 is 0.0 and the proportion of bleached pulp fibers 141 is 1.0 (in other words, when a sheet is formed only from bleached pulp fibers 141), the pulp fiber of the sheet has a kappa number of 1.0. The sheet k in the bottom column of table 1 shows that the pulp fiber of the sheet had a kappa number of 25.0 when the sheet was formed under the conditions that the ratio of the unbleached pulp fibers 142 was 25.0 and the ratio of the bleached pulp fibers 141 was 0.0 (in other words, when the sheet was formed only from the unbleached pulp fibers 142). In the sheet b in the second upper column of table 1, the kappa number K1 of unbleached pulp fiber 142 per unit weight was 2.5, and the kappa number of bleached pulp fiber 141 per unit weight was 0.9, so that the kappa number of the pulp fiber of the sheet was 3.4.
[ Table 1]
Figure BDA0003555716320000191
When the liquid-absorbent core, the 1 st core covering sheet, the leakage-preventive sheet, and the back sheet were laminated in this order and observed with the naked eye from the back sheet side, an evaluation experiment was conducted to determine whether the appearance was light brown. The subject can visually recognize that the pieces d to k are light brown, and the subject can visually recognize that the pieces a to c are white. Thus, the pulp fiber of the 1 st core covering sheet 122a preferably has a kappa number of more than 8.2. Further, it is clear that if the degree of unbleached is increased by appropriately avoiding the bleaching step and the pulp fiber is formed into a sheet having a kappa number of 40.0, the sheet becomes brown without an unnatural feeling, and therefore the kappa number is preferably less than 40.0.
Further, the pulp fiber of the core covering sheet 122 formed only of the bleached pulp fiber 141 had a kappa number of 1.0. Therefore, when the sheet a in table 1 is used for the 2 nd core covering sheet 122b and the sheet d is used for the 1 st core covering sheet 122a, the kappa number of the pulp fiber of the sheet d is 8.2, and thus the difference between the two is 7.2. When the sheet d is used as the 1 st core covering sheet 122a, the kappa number of the pulp fibers of the sheet d is 8.2, and when the sheet c is used as the 2 nd core covering sheet 122b, the kappa number of the pulp fibers of the sheet c is 5.8, and therefore the difference between the two is 2.4. From the above results, it is preferable that the kappa number of the pulp fiber of the 1 st core covering sheet 122a is 8 to 40, and the difference between the kappa number of the pulp fiber of the 2 nd core covering sheet 122b and the kappa number of the pulp fiber of the 1 st core covering sheet 122a is 2.4 or more. More preferably, the kappa number of the pulp fiber of the 1 st core covering sheet 122a is 8 to 40, and the difference between the kappa number of the pulp fiber of the 2 nd core covering sheet 122b and the kappa number of the pulp fiber of the 1 st core covering sheet 122a is 7.2. As a reason for using the above-described sheet, the use of a white sheet for the 2 nd core covering sheet 122b on the non-skin-facing surface side can give an impression that a product having a clean feeling is given to users and caregivers, and therefore, it is preferable to use at least the sheet c, and more preferably the sheet a. Further, since the use of a light brown sheet for the 1 st core covering sheet 122a on the skin-facing surface side can give an impression that the article is a natural article having a high intention using natural materials, it is preferable to use at least the sheet d.
Table 2 shows the L value, a value, b value, and Δ E value in the Lab color system of the sheet formed by changing the ratio of the bleached pulp fibers 141 [% ] and the ratio of the unbleached pulp fibers 142 [% ]. The measuring instrument and the measuring method are the same as those described later.
[ Table 2]
Figure BDA0003555716320000211
The test subjects observed the tablets in table 2, and performed an evaluation test of whether or not the tablets were light brown. Thus, most of the subjects were recognized as light brown for the slice D, and almost all of the subjects were recognized as light brown for the slice E.
Therefore, the L value, the a value and the b value in the Lab color system observed when the first core covering sheet 122a is observed from the skin-facing surface side preferably satisfy
82.81 < L > and 92.53 < L ≤
-0.24. ltoreq. the a value. ltoreq.1.57
9.08 is less than or equal to the b value is less than or equal to 17.87
All conditions in (1).
Further, according to the experimental results described later, it is preferable that the L value, the a value and the b value in the Lab color system observed when the absorbent body including the 1 st core covering sheet 122a is observed from the skin-facing surface side satisfy
70.00 or more and the L value is 90.00 or less
0.50 or more and the a value is less than or equal to 10.00
7.00 or more and the b value is 15.00 or less
All conditions in (1).
Further, as shown in fig. 3 and 4, both side edges 122c, 122d of the 1 st core covering sheet 122a and both side edges 122e, 122f of the 2 nd core covering sheet project outward in the transverse direction of both side edges 121a, 121b of the liquid-absorbent core 121, and the 1 st core covering sheet 122a and the 2 nd core covering sheet 122b are joined at a joining portion 127 outside in the transverse direction X of both side edges 121a, 121b of the liquid-absorbent core 121. Therefore, the visually recognizable area of the 1 st core covering sheet 122a as viewed from the skin-facing surface side can be enlarged as much as possible to increase the portion having a color tone derived from wood, and an impression of an article having a high natural intention using natural materials can be given. Further, since the dimension in the transverse direction X of the 2 nd core covering sheet 122b is larger than the dimension in the transverse direction X of the 1 st core covering sheet 122a and the entire area of the 1 st core covering sheet 122a is covered with the 2 nd core covering sheet 122b, it is difficult to visually recognize the light brown color of the 1 st core covering sheet 122a when the diaper 101 is viewed from the non-skin-facing surface side, and an impression of an article having a clean feeling can be given to a third person.
The length of the joint 127 is 50mm or less. Therefore, the use of an adhesive such as a hot-melt adhesive can be reduced as much as possible, and the waste of materials can be suppressed.
< embodiment 2 of the invention 1 >
Fig. 6 is a developed plan view of the diaper 101 according to embodiment 2 of the invention 1, similar to fig. 2, fig. 7 is a perspective view of a topsheet 131a used in the absorber 120 of the diaper 101, and fig. 8 is a sectional view taken along line VIII-VIII of fig. 6. Since the basic structure of the diaper 101 of the present embodiment is the same as that of the diaper 101 of embodiment 1, only the differences will be described below.
The front sheet 131a has convex portions 161 and concave portions 162 extending in the longitudinal direction Y and alternately arranged in the lateral direction X, respectively, and the concave portions 162 contact the absorber 120 while the convex portions 161 are spaced apart from the absorber 120. Therefore, the brown color of the 1 st core covering sheet 122a can be reduced for the convex portion 161, and the user can be given an impression of a clean article.
The 1 st core covering sheet 122a has both side edge portions 122c and 122d located between the non-skin-facing surface of the liquid-absorbent core 121 and the 2 nd core covering sheet 122 b. Therefore, the area of the 1 st core covering sheet 122a that can be visually recognized from the skin-facing surface can be reduced as much as possible, and the white area can be enlarged, so that the user can be given an impression of a clean article.
Further, a total W3 of a dimension W1 in the transverse direction X of one side edge portion 122c and a dimension W2 in the transverse direction X of the other side edge portion 122d of the 1 st core covering sheet 122a in the transverse direction X is smaller than 1/3 of a dimension W4 in the transverse direction X of the liquid-absorbent core 121. Therefore, the 2 nd core covering sheet 122b can be visually recognized from the non-skin-facing surface, and the presence or absence of urination can be prevented from being erroneously recognized.
Although not shown, the 1 st core covering sheet 122a may be superposed on the outer sides of the side edges 121a, 121b of the liquid-absorbent core 121 in the transverse direction X in the thickness direction Z. This makes it possible to make the brown color of the side edges 121a and 121b of the liquid-absorbent core 121 darker and to allow the user to recognize the position of the liquid-absorbent core 121.
< embodiment 3 of the 1 st invention >
Fig. 9 is an expanded plan view of the diaper 101 according to embodiment 3 of the 1 st invention similar to fig. 2, and fig. 10 is a cross-sectional view taken along line X-X of fig. 9. Since the basic structure of the diaper 101 of the present embodiment is the same as that of the diaper 101 of embodiment 1, only the differences will be described below.
In this diaper 101, a member independent from the surface sheet 131 and the 1 st core covering sheet 122a, that is, the intermediate sheet 139 is located between the surface sheet 131 and the 1 st core covering sheet 122 a. The intermediate sheet 139 is made of bleached pulp fibers, or is white by mixing a pigment such as titanium dioxide with the constituent fibers. Therefore, the user can grasp the position of the intermediate sheet 139 with the light brown 1 st core covering sheet 122 a.
In the diaper 101, the indicator 171 for indicating the presence or absence of excrement such as urine is positioned on the non-skin-facing surface side of the liquid-absorbent core 121, and the indicator 171 and the 2 nd core covering sheet 122b are superposed on each other in the thickness direction Z. Since the 2 nd core covering sheet 122b around the indicator portion 171 is white, it is possible to prevent erroneous confirmation of the presence or absence of urination.
Table 3 shows the L value, a value, b value, and Δ E value in the Lab color system of the diaper manufacturer's instruction unit. The measuring instrument and the measuring method are the same as those described later.
[ Table 3]
Value of L a value of b value Delta E value
Indication part of A company diaper 90.29 1.34 15.85 5.21
Diaper indicator of company B 89.48 -4.03 15.69 5.43
Indication part of diaper of company C 82.97 -1.79 22.72 10.51
Indication part of diaper of company D 82.34 -3.12 19.70 9.89
As shown in Table 3, the b value of the indication part of each company is 15.85 to 22.72, and is yellow. The indicator 171 used in the present invention is also included in this range. Since the 2 nd core covering sheet 122b of this diaper 101 is white, the position of the indicator 171 can be easily visually recognized.
< embodiment 4 of the invention 1 >
Fig. 11 is an expanded plan view of the diaper 101 according to embodiment 4 of the 1 st invention similar to fig. 2. Since the basic configuration of the diaper 101 of the present embodiment is the same as that of the diaper 101 of embodiment 1, only the differences will be described below.
In the absorber 120 of this diaper 101, superabsorbent polymer particles 163 are present between the facing surfaces of the 1 st core covering sheet 122a and the 2 nd core covering sheet 122 b. The absorber 120 has: a 1 st joining region 164 in which the superabsorbent polymer particles 163 are fixed to the sheets 122a, 122b by an adhesive such as a hot melt adhesive in the 1 st joining region 164; and a 2 nd bonding region 165 disposed around the 1 st bonding region 164, wherein the 1 st core covering sheet 122a and the 2 nd core covering sheet 122b are directly bonded to each other in the 2 nd bonding region 165 by a bonding agent such as a hot melt adhesive. The 1 st joining regions 164 are arranged with a space in the longitudinal direction Y, and the 2 nd joining region 165 is arranged between the plurality of 1 st joining regions 164. Further, the liquid-absorbent core 121 is formed only of the super absorbent polymer particles 163.
< embodiment 5 of the 1 st invention >
Fig. 12 shows an example of use of the absorbent article of the invention 1, and in this embodiment, the absorbent body 120 is applied to a sanitary napkin (absorbent article) 180.
The sanitary napkin 180 includes a skin-facing surface (inner surface) side and a non-skin-facing surface (outer surface) side opposite thereto, a convex 1 st edge 180a and a convex 2 nd edge 180b, a convex 1 st side edge 180c and a convex 2 nd side edge 180d at a central portion of a transverse center line Q, a liquid-permeable top sheet 131 positioned on the skin-facing surface side, a stretchable and liquid-impermeable back sheet 132 positioned on the non-skin-facing surface side, and a liquid-absorbent body 120 positioned between the two sheets 131 and 132.
The absorbent body 120 has a 1 st end edge 120a opposed to the 1 st end edge 180a, a 2 nd end edge 120b opposed to the 2 nd end edge 180b, and a 1 st side edge 120c and a 2 nd side edge 120d extending in the longitudinal direction between the 1 st end edge 120a and the 2 nd end edge 120 b. The front sheet 181 and the back sheet 182 extend outward from the outer periphery of the absorbent body 120, and a pair of side sheets 184 extending in the longitudinal direction Y so as to face each other in the transverse direction X are arranged on the skin-facing surface side of the front sheet 181. The pair of side sheets 184 are joined to the surface sheet 181 by side joining portions (not shown) formed by a known adhesive means or welding means.
The flaps 188 formed by the parts of the side edges 187, which project outward in the transverse direction X, are located in the central portion in the longitudinal direction Y of the sanitary napkin 180. The sheets 181, 182, and 184 stacked on each other are joined to each other by an outer peripheral seal 189 located along the outer peripheral edge of the sanitary napkin 180.
Since the entire core covering sheet 122 is light brown derived from a plant material such as wood, when artificial menstrual blood (5ml) is dropped onto the liquid absorbent core 121 via the surface sheet 181, the a value, b value, and L value of the laa b color system (laa b color space, hereinafter abbreviated as "lab") are measured in the menstrual blood absorbing region observed from the skin-facing surface side and the menstrual blood non-absorbing region including the liquid absorbent core 121. The weight per unit area of the 1 st core covering sheet 122a having no intermediate sheet and having a weight per unit area of 14g/m was used in example 1 2In example 2, the sanitary napkin 180 according to (1) is used without an intermediate sheet, and the weight per unit area of the first core covering sheet 122a is 20g/m2The sanitary napkin 180. Further, for comparison with examples 1 to 2, the weight per unit area of the 1 st core covering sheet 122a having the 1 st core covering sheet containing a lignin component and the intermediate sheet containing no lignin component was 14g/m2The sanitary napkin of comparative example 1, which used a white core covering sheet containing no lignin component and a surface sheet made of cottonIn the same manner as in the sanitary napkin of comparative example 2 and the sanitary napkin of comparative example 3 in which a white core covering sheet containing no lignin component was used and cotton was not used as the topsheet, the standard menstrual blood was dropped onto the liquid-absorbent core 121 via the topsheet, and at this time, the a value, b value and L value of the Lab color system were measured in the menstrual blood-absorbing region and the menstrual blood-non-absorbing region observed from the skin-facing surface side. The experimental results are shown in tables 4 to 7. Further, as the artificial menstrual blood, a liquid obtained by mixing appropriate amounts of ionic water, glycerin, sodium carboxymethylcellulose, sodium chloride, sodium bicarbonate, pigment Red No. 102, pigment Red No. 2, and pigment yellow No. 5 (each pigment is manufactured by Takara Shuzo Co., Ltd.) was used.
(method of measuring color difference)
Color difference measurement was performed in accordance with JIS Z8722 using a color difference meter ZE6000 (standard white board [ X: 93.19, Y: 95.20, Z: 112.28], reflection measurement diameter 30mm, manufactured by japan electro-chromatic industries co. The measurement was performed 5 times for each sample, and the average value of the measurement values was defined as the L value, a value, and b value of each sample.
[ Table 4]
a value of
Example 1 Example 2 Comparative example 1 Comparative example 2 Comparative example 3
Non-absorbent region 0.67 2.63 0.59 -0.75 -0.76
Absorbent region 49.64 49.10 52.97 51.52 55.45
Difference between the two 49.17 46.47 52.38 52.27 56.21
Evaluation of ○ ○ × × ×
The a-value relates primarily to red and green, with red for larger values and green for smaller values. The green color is darker when it becomes negative. Referring to table 4, in the sanitary napkins of comparative examples 2 and 3, since the white core covering sheet was used, the a value in the non-absorbent region was negative, while the a value in the absorbent region was 50.0 or more, and the difference between the two values was large, and the red color in the absorbent region was conspicuous. On the other hand, in the sanitary napkins of examples 1-2, since the 1 st core covering sheet 122a is light brown, the a value in the non-absorbent region is 0.5 or more, which is a positive number, the a value in the absorbent region is less than 50.0, and the difference between the two is 50 or less, so that the condition that the red color in the absorbent region becomes conspicuous can be suppressed. On the other hand, in the sanitary napkin of comparative example 1, the a value of the non-absorbent region is positive since the core covering sheet is light brown, but the a value of the absorbent region is more than 50 since the white intermediate sheet is used. Thus, the red color of the absorption region is more conspicuous. In view of the above, the a value of the non-absorption region is preferably 0.50. ltoreq. a value.ltoreq.10.00. The value a of the absorption region is preferably 50 or less. The difference between the absorption region and the non-absorption region is preferably 50 or less. Regarding the value of a, the sanitary napkins of examples 1 and 2 are preferable, and the sanitary napkins of comparative examples 1 to 3 are not preferable.
[ Table 5]
b value
Example 1 Example 2 Comparative example 1 Comparative example 2 Comparative example 3
Non-absorbent region 9.61 10.47 6.89 2.72 7.78
Absorbent region 23.25 26.61 29.69 27.49 31.47
Difference between the two 13.64 16.14 22.80 24.77 23.69
Evaluation of ○ ○ × × ×
The b-value relates primarily to yellow and blue, with yellow at higher values and blue at lower values. Referring to table 5, in the sanitary napkin of comparative example 2, since the white core covering sheet was used, the b value in the non-absorbent region was less than 7, the b value in the absorbent region was more than 27, the difference between the two was more than 20, the difference between the two was large, and the yellow color in the absorbent region was conspicuous. In the sanitary napkin of comparative example 3, since the white core covering sheet was used, the b value in the absorbent region was larger than 27, the difference between the two was large, and the yellow color in the absorbent region was conspicuous. On the other hand, in the sanitary napkins of examples 1-2, since the 1 st core covering sheet 122a is light brown, the b value in the non-absorbent region is 7 or more and 15 or less, the b value in the absorbent region is 30 or less, and the difference between the two is 20 or less, so that the yellow color in the absorbent region can be suppressed from becoming conspicuous. On the other hand, in the sanitary napkin of comparative example 1, a light brown core covering sheet was used, but since a white intermediate sheet was used, the b value of the non-absorbent region was less than 7 (blue color was observed when the b value was close to 0). Therefore, the color difference between the absorption region and the non-absorption region is large, and the color of the absorption region cannot be suppressed from being conspicuous. In view of the above, the b value of the non-absorption region is preferably 7.00. ltoreq. b value.ltoreq.15.00. The b value of the absorption region is preferably 30 or less. The difference between the absorption region and the non-absorption region is preferably 20 or less. Regarding the b value, the sanitary napkins of examples 1 and 2 are preferable, and the sanitary napkins of comparative examples 1 to 3 are not preferable.
The L value relates to the brightness of the color, with white at higher values and black at lower values. Referring to Table 6, the L value is preferably 70 or more and 90 or less (70.00. ltoreq. L value. ltoreq.90.00). Regarding the L value, the sanitary napkins of examples 1 and 2 are preferable, and the sanitary napkins of comparative examples 1 to 3 are not preferable.
[ Table 6]
Value of L
Example 1 Example 2 Comparative example 1 Comparative example 2 Comparative example 3
Non-absorbent region 90.26 84.15 91.18 93.43 94.18
Absorbent region 28.77 30.85 32.24 31.21 33.94
Difference between the two 61.49 53.30 58.94 62.22 60.24
Evaluation of ○ ○ × × ×
Further, the entire 1 st core covering sheet 122a is light brown derived from a plant material such as wood, the absorber 120 is light brown, and the wing portions 188 are white. Therefore, an attempt was made to measure the a value of the Lab color system for the absorbent body 120 containing the liquid-absorbent core 121 and the wing portions 188 not containing the absorbent body 120. In example 1, the absorbent core having no intermediate sheet and having a weight per unit area of 14g/m was used2The sanitary napkin 180. In addition, for comparison with example 1, the same applies to the sanitary napkins of comparative examples 1 to 3 each using a core covering sheet containing no lignin componentAn attempt was made to measure the a value of the Lab color system for the absorbent body 120 containing the liquid-absorbent core 121 and the wing portion 188 not containing the absorbent body 120. The experimental results are shown in table 7.
[ Table 7]
a value of
Example 1 Comparative example 1 Comparative example 2 Comparative example 3
Absorbent body 0.59 -0.75 -0.67 -0.89
Wing part -0.64 -0.64 -0.56 -0.64
Difference between the two 1.23 0.11 0.11 0.25
Evaluation of ○ × × ×
As shown in table 7, only the sanitary napkins of example 1 had a difference of 0.5 or more, while the sanitary napkins of comparative examples 1 to 3 had a difference of less than 0.5. When the difference between the both is 0.5 or more, the boundary between the periphery of the absorbent body and the other region including the wing sections 188 is conspicuous, and therefore, the wearer or the caregiver can grasp the position of the absorbent body 120, which is preferable.
In the above-described embodiment, the liquid-absorbent core 121 does not contain a lignin component. However, the present invention is not limited thereto, and the liquid-absorbent core 121 may contain a lignin component.
In the above embodiment, a so-called pant-type diaper in which both side edge portions of the front waist region and the rear waist region are joined in advance has been described. However, the present invention is not limited to this, and can be applied to an open-type diaper.
The various embodiments of the invention disclosed above can be used in isolation or in combination with one another.
As long as it is not specifically described, the member constituting the absorbent article can be made of any known material that is generally used in this field, in addition to the materials described in the present specification, without limitation. In addition, the terms "1 st" and "2 nd" and the like used in the present specification are used only for distinguishing the same elements, positions and the like.
< invention 2 >
The following embodiment of invention 2 relates to the absorbent article shown in the drawings, and includes not only the indispensable structure of the invention but also optional and preferable structures.
< embodiment 1 of the invention 2 >
Hereinafter, an embodiment of a sanitary napkin 210 as an example of an absorbent article of the present invention will be described with reference to the drawings. The sanitary napkin 210 has a longitudinal direction Y, a transverse direction X, and a thickness direction Z that intersect (intersect) with each other.
Referring to fig. 13 to 15, the sanitary napkin 210 has a longitudinal center line P bisecting the dimension in the width direction thereof and a transverse center line Q bisecting the dimension in the longitudinal direction thereof, and includes a skin-facing surface (inner surface) side and a non-skin-facing surface (outer surface) side opposite thereto, a convex curved first end edge 210a and second end edge 210b, a convex curved first side edge 210c and second side edge 210d at a central portion where the transverse center line Q is located, a liquid-permeable top sheet 211 positioned on the skin-facing surface side, a liquid-impermeable back sheet 212 positioned on the non-skin-facing surface side, and a liquid-absorbent body 220 positioned between the two sheets 211, 212. The top sheet 211 and the absorber 220 are joined to each other by a known joining means such as a hot melt adhesive to form the liquid absorbent layer 213.
Further, although not shown, an intermediate sheet made of a relatively bulky fibrous nonwoven fabric may be disposed between the top sheet 211 and the absorbent member 220 in order to improve the flexibility of the sanitary napkin 210. In order to suppress leakage of bodily fluids, a leakage preventing sheet, preferably having air permeability and made of liquid impermeable fibrous nonwoven fabric or plastic film, may be disposed between the absorbent body 220 and the back sheet 212.
The absorbent body 220 has a 1 st end edge 220a opposite to the 1 st end edge 210a, a 2 nd end edge 220b opposite to the 2 nd end edge 210b, and a 1 st side edge 220c and a 2 nd side edge 220d extending in the longitudinal direction between the 1 st end edge 220a and the 2 nd end edge 220 b. The front sheet 211 and the back sheet 212 protrude outward from the outer periphery of the absorbent body 220. A pair of side sheets 214 extending in the longitudinal direction Y so as to face each other in the lateral direction are disposed on the skin-facing surface side of the top sheet 211. The pair of side sheets 214 are joined to the front sheet 211 by side joining sections (not shown) formed by a known adhesive means or welding means. Although not shown, in the side sheet 214, in order to form a leakage preventing wall that rises toward the body side in a worn state, an elastic member extending in the longitudinal direction Y may be disposed so as to be contractible in an extended state on the side sheet 214. The side joint portion for fixing the side sheet 214 may be a seal line extending in the longitudinal direction Y and having design elements such as a pattern and a geometric pattern.
The sanitary napkin 210 has both end portions 216 formed of the front sheet 211, the back sheet 212 and the side sheets 214 and extending in the transverse direction X outside the longitudinal direction Y of the 1 st end edge 220a and the 2 nd end edge 220b of the absorbent body 220, and both side edge portions 217 extending in the longitudinal direction Y outside the transverse direction X of the 1 st side edge 220c and the 2 nd side edge 220d of the absorbent body 220. The flaps 218 formed by the parts of the side edges 217 protruding outward in the transverse direction X are located in the central portion in the longitudinal direction Y of the sanitary napkin 210. The sheets 211, 212, 214 stacked on each other are joined to each other by a peripheral seal part 219 located along the outer peripheral edge of the sanitary napkin 210.
Referring to fig. 14, a plurality of fastening regions 230 are disposed on the back side of the sanitary napkin 210. The fastening regions 230 are used for fastening the sanitary napkin 210 to clothing such as underwear, and the plurality of fastening regions 230 are formed by an adhesive or a pressure-sensitive adhesive applied in a plurality of lines extending in the longitudinal direction Y. The fastening region 230 has a central region 231 extending in the longitudinal direction Y in a region overlapping with the absorbent body 220 and side regions 232 located at the wings 218. The fixing region 230 is covered with a spacer (not shown) made of a plastic film.
The surface sheet 211 can be made of various liquid-permeable nonwoven fabrics of fibers, for example, having a basis weight of about 15g/m 2～45g/m2The nonwoven fabric of air-through fibers, the porous plastic film, the laminate of the above materials, and the like. The back sheet 212 may be formed of a liquid-impermeable and moisture-permeable plastic film, a liquid-impermeable fibrous nonwoven fabric, a laminate of the above materials, or the like. The side sheet 214 can be the same sheet as the front sheet 211. However, in order to effectively prevent the side leakage of body fluid, it is preferable to use a sheet having hydrophobicity or waterproofness.
As the surface sheet 211, a sheet having an uneven surface side can be used. The surface of the sheet is formed by a plurality of concave portions and a plurality of convex portions alternately arranged in the longitudinal direction Y or the transverse direction X, and as a method for forming the plurality of convex portions and concave portions, for example, a method for forming a dense portion and a bulky portion by controlling the amount of fibers, a method for forming concave portions by embossing, a method for forming concave portions into a concave-convex shape, and the like are considered. The fibers are arranged in the convex portion and the concave portion so as to be sparse one and dense the other in such a manner that the fiber densities are different from each other. The joining strength can be further improved by joining the portion where the fibers are sparsely arranged (portion 1) to the high lignin region 252 of the core covering sheet 222 described later, while the liquid absorption can be further improved by joining the portion where the fibers are densely arranged (portion 2) to the low lignin region 251.
Even when menstrual blood is repeatedly excreted for a relatively short period of time, the menstrual blood can be temporarily accumulated in the concave portions, and leakage of menstrual blood from the surface of the surface sheet 211 and between the surface sheet 211 and the core covering sheet 222 can be suppressed. Further, it is preferable that a part of the concave portion of the surface sheet 211 is substantially (continuously or discontinuously) surrounded by a compressed portion in which a compressed groove is formed, a compressed concave portion formed by embossing, or the like. In this case, the body fluid accumulated in the dent can be prevented from leaking out in the lateral direction X and the longitudinal direction Y. In addition, in the case where the surface of the surface sheet is uneven, the core covering sheet 222 of light brown color is visually recognized as darker in color than the convex portion in the concave portion in the surface view, and therefore, a decorative effect by the gradation of color can be produced.
The outer peripheral seal part 219 may be bonded with an adhesive, bonded with a known welding means such as ultrasonic welding, thermal welding, laser welding, or high-frequency welding, or bonded with embossing, either alone or in combination. The sheets 211, 212, 214 stacked in the thickness direction Z are bonded to each other by an adhesive such as a hot melt adhesive. Examples of the method for applying the hot melt adhesive include various known coating methods such as spiral coating, coater coating, curtain coater coating, and spray coating.
Referring to fig. 15 and 16, the absorbent body 220 includes a liquid-absorbent core 221 formed by mixing superabsorbent polymer particles (SAP) and cellulose fibers such as fluffed wood pulp and rayon fibers and shaped into a predetermined shape, and a liquid-permeable core covering sheet 222 wrapping the entire liquid-absorbent core 221 to improve shape retention and liquid diffusion properties of the absorbent body 220.
The dimension in the longitudinal direction Y of the core covering sheet 222 is larger than the dimension in the longitudinal direction Y of the liquid-absorbent core 221, and both side edge portions 222a, 222b thereof are positioned so as to overlap each other on the bottom surface side of the central portion in the transverse direction X of the liquid-absorbent core 221 so as to wrap the entire liquid-absorbent core 221. By stacking the both side edge portions 222a, 222b, an overlapping portion 223 is formed in the central portion of the absorbent body 220 in the transverse direction X, and the overlapping portion 223 is formed by stacking the both side edge portions 222a, 222b extending in the longitudinal direction Y.
The core covering sheet 222 has a 1 st covering portion 225 covering the skin-facing surface side of the liquid-absorbent core 221 and a 2 nd covering portion 226 covering the non-skin-facing surface side of the liquid-absorbent core 221. In the present embodiment, the core covering sheet 222 is formed of one continuous sheet, but may be formed of a 1 st core covering sheet forming the 1 st covering portion 225 and a 2 nd core covering sheet independent of the 1 st core covering sheet and forming the 2 nd covering portion 226.
Referring to fig. 17, the core covering sheet 222 is formed of various well-known fibrous nonwoven fabrics or tissue papers, mainly pulp fibers 240. The pulp fibers 240 of the core cover sheet 222 have bleached pulp fibers 241 that have been delignified and unbleached pulp fibers 242 that have not been delignified. Here, the pulp fiber 240 contains, in addition to a wood pulp fiber obtained from a conifer or a hardwood tree as a raw material, a non-wood pulp fiber obtained from cotton linter, abaca, hibiscus hemp, straw, bamboo, or banana as a raw material.
The core covering sheet 222 may have a multilayer structure including, for example, a 1 st layer (upper layer or lower layer) composed of regenerated cellulose fibers such as rayon fibers and hydrophilic fibers such as semi-synthetic cellulose fibers, and a 2 nd layer (lower layer or upper layer) composed of unbleached pulp fibers 242 that have not been subjected to delignification treatment. In this case, even when the 2 nd layer has a sea-island structure composed of the low lignin region 251 and the high lignin region 252 as described later, the body fluid can be sufficiently diffused in the 1 st layer, and thus the unevenness of the body fluid diffusion in the entire core covering sheet 222 can be suppressed. Thus, even after a plurality of times of absorption of body fluid, the deterioration of the bondability between the core covering sheet 222 and the top sheet 211 can be suppressed, and a preferable liquid-absorbing property can be maintained.
The pulp fiber 240 is generally a bleached pulp fiber 241 obtained by subjecting a raw material chip to a raw material chip treatment step, then to a cooking step (a 1 st stage of delignification treatment) of adding a chemical to the raw material chip and boiling the raw material chip under high temperature and high pressure to cook lignin, a screening step of removing foreign matters in the pulp, an oxygen exposure step (a 2 nd stage of delignification treatment) of decomposing lignin remaining in the cooking step with oxygen, and a bleaching step of bleaching the pulp with various chemicals. The unbleached pulp fiber 242 is obtained by only passing through the cooking step and the screening step, which are the 1 st stage of the delignification treatment, among the above-described steps, and is obtained by performing the delignification treatment to a certain degree. The lignin content of the unbleached pulp fiber 242 is 0.2-10.0%.
The lignin content of the unbleached pulp fiber 242 was measured by the following method.
< method for measuring Lignin content >
Quantification of ADF
Reagent: an acid detergent solution (Hexadecyltrimethylammonium Bromide Bromide)10g was dissolved in 500mL of 1N sulfuric acid to obtain a chemical >
Acetone (II)
Decalin as an antifoaming agent (alternative)
< measurement procedure >
A sample (300 g) was weighed, placed in a 50mL Erlenmeyer flask, and 30mL of an acidic detergent solution was added. The flask was covered with aluminum foil, and the flask was placed in boiling water to decompose the product for 60 minutes. After the decomposition, it was transferred to a glass fiber filter paper (GA-200) -laid Gu's crucible and subjected to suction filtration, and the residue was washed with hot water and acetone. After air drying, thermal drying is carried out. The ash obtained by removing ash by taking a constant amount after drying is ADF, but ash obtained by quantifying lignin cannot be used for this purpose.
Lignin quantification
Reagent: 72% sulfuric acid
< measurement procedure >
A few drops of 72% sulfuric acid were dropped into the above-described dry gouge crucible to wet the whole, and then about twice the amount of ADF was added, and the sulfuric acid was appropriately added every hour and left for 3 to 4 hours. Thereafter, the reaction mixture was subjected to suction filtration and washed with hot water until the furnace liquid showed no acidity. After air drying, heat drying was carried out and a constant amount was taken. Ashing was performed at 550 ℃ in a Gu-Shi crucible to determine ash content.
The 1 st coating portion 225 of the core covering sheet 222 has a low lignin region (lignin low content region) 251 in which the content of the lignin component is relatively low, and a high lignin region (lignin high content region) 252 in which the content of the lignin component is relatively high compared to the low lignin region 251. The low lignin regions 251 are formed primarily of a collection of bleached pulp fibers 241 and the high lignin regions 252 are formed primarily of a collection of unbleached pulp fibers 242. In a plan view of the 1 st coating portion 225 of the core covering sheet 222, the low lignin regions 251 are peripheral regions located in a relatively large range of the outer surface of the core covering sheet 222, while the high lignin regions 252 are disposed so as to be scattered in the low lignin regions 251. In addition, since the core covering sheet 222 or at least the 1 st coating portion 225 has such an arrangement, it can be said that the entire core covering sheet 222 or the core covering sheet has a sea-island structure in which the low lignin region 251 is a sea and the high lignin region 252 is an island.
Since the core covering sheet 222 has a plurality of high lignin regions 252, it has a light brown color derived from a plant material such as wood as a whole. Since the other sheets 211, 212, and 214 than the core covering sheet 222 are colored white as a whole by mixing a white pigment such as titanium dioxide with the constituent fibers, the core covering sheet 222 can be easily visually recognized through the other sheets 211, 212, and 214 in the front view and/or the back view of the sanitary napkin 210.
In the core covering sheet 222 of the present embodiment, the mixture of the bleached pulp fibers 241 and the unbleached pulp fibers 242 is formed into a sheet by being entangled in the paper making process, and since the bleached pulp fibers 241 are mainly arranged in the low-lignin region 251 and the unbleached pulp fibers 242 are mainly arranged in the high-lignin region 252, the boundary between the two regions 251 and 252 is not clear and cannot be clearly distinguished. As a method for forming the high lignin regions 252 so as to be dispersed in the low lignin regions 251 over the entire outer surface of the core covering sheet 222, for example, a mixing method of the pulp fibers 241 and 242, a mixing ratio, a conveying speed of a conveyor at the time of production, a nozzle diameter at the time of depositing the pulp fibers 240 on the conveyor by air jetted from a plurality of nozzles, an air volume of blown air, an air velocity, and the like may be appropriately adjusted.
Since the two regions 251 and 252 are formed by adjusting various conditions of the production process, it can be said that the unbleached pulp fibers 242 are contained in a part of the low lignin region 251 and the bleached pulp fibers 241 are contained in the high lignin region 252. Therefore, the low-lignin region 251 and the high-lignin region 252 are not formed of only the bleached pulp fibers 241 and the unbleached pulp fibers 242, respectively, but may contain fibers other than pulp fibers, for example, the content of the bleached pulp fibers 241 in the pulp fibers of the low-lignin region 251 is 50% to 100%, and the content of the unbleached pulp fibers 242 in the pulp fibers of the high-lignin region 252 is 50% to 100%.
The high-lignin region 252 is a region having a higher content of lignin component than the low-lignin region 251 which is a peripheral region of the core covering sheet 222, and therefore the high-lignin region 252 can be formed without using a sheet in which the bleached pulp fibers 241 and the unbleached pulp fibers 242 are mixed. For example, the high lignin region 252 having a higher lignin content than the peripheral region can be formed by allowing a liquid containing a lignin component to dispersedly infiltrate into a fibrous nonwoven fabric sheet composed of rayon fibers or synthetic fibers.
Since the core covering sheet 222 has the plurality of high lignin regions 252 mainly composed of the unbleached pulp fibers 242, it has a light brown color (wood color) derived from a plant material in a surface view, as compared with the case of using a core covering sheet composed of only unbleached pulp fibers, and can give an impression that a wearer or a wearer assistant is a product which is mild to the skin and is made of a natural material. Further, since the core covering sheet 222 has a light brown color, the degree of redness of menstrual blood is suppressed when the menstrual blood excreted permeates the top sheet 211 and is absorbed and held by the absorbent body 220. This can suppress aversion caused by direct visual recognition of menstrual blood, and can alleviate mental uneasiness caused by visual recognition of the redness of menstrual blood for example in wearers of menstrual onset. Further, since the lignin component has an antibacterial action, the propagation of mixed bacteria after use can be suppressed and the disposal can be performed hygienically.
The core covering sheet 222 preferably has a lignin content of 0.2% to 10% in order to exhibit its natural appearance, suppression of the redness of menstrual blood, and a certain antibacterial effect. When the content of the lignin component in the core covering sheet 222 is less than 0.2%, the color of the light brown color of the core covering sheet 222 may be so light that it cannot be visually distinguished from the other white sheets 211, 212, and 214. On the other hand, when the content of the lignin component in the core covering sheet 222 is greater than 10%, the chroma of the lignin component is deep, and the natural appearance of the natural material may be impaired, and the redness of menstrual blood may be difficult to visually recognize, and the menstrual blood volume may not be accurately grasped.
In general, the core covering sheet has not only the function of keeping the shape of the liquid-absorbent core but also the function of absorbing and diffusing body fluid having passed through the topsheet and transferring the body fluid to the liquid-absorbent core, and therefore, it is preferable to use a hydrophilic sheet. Since the unbleached pulp fibers 242 in the high-lignin region 252 contain a large amount of lignin component, they have a low degree of hydrophilicity and are relatively hydrophobic, and therefore, for example, when the entire 1 st coating section 225 is formed of the high-lignin region 252, menstrual blood that has permeated the surface sheet 211 cannot be absorbed and retained in the high-lignin region 252, and the menstrual blood cannot be rapidly transferred to the liquid-absorbent core 221.
Referring to fig. 18, since the 1 st cladding 225 of the core covering sheet 222 has a low lignin region 251 and a plurality of high lignin regions 252 scattered around the low lignin region 251, the two regions 251, 252 described above appear alternately in the transverse direction X in a cross-sectional view. Since the high lignin regions 252 are disposed so as to be scattered in the low lignin region 251, it can be said that the low lignin regions 251 and the high lignin regions 252 are alternately disposed not only in the lateral direction X but also in the longitudinal direction Y.
By positioning the low-lignin regions 251 and the high-lignin regions 252 at alternating positions in the transverse direction X and the longitudinal direction Y in the cross-sectional view of the 1 st coating section 225 in this way, menstrual blood that has permeated the top sheet 211 in the hydrophilic low-lignin regions 251 can be absorbed and held by being rapidly transferred to the liquid-absorbent core 221, and a desired absorption rate can be achieved.
In addition, in the hydrophilic low-lignin region 251, there is a possibility that menstrual blood is absorbed and the bleached pulp fibers are swollen, so that the bonded portions are peeled off at the bonded interface between the surface sheet 211 and the core covering sheet 222 by the hot melt adhesive, and the bonding strength is lowered. On the other hand, the high lignin region 252 is less hydrophilic and hydrophobic than the low lignin region 251, and therefore, it is less likely to absorb menstrual blood and swell, and the bonded portion does not peel off, and the bonding strength at the bonding interface between the core covering sheet 222 and the surface sheet 211 is higher than that of the low lignin region 251.
Therefore, the bonding strength between the core covering sheet 222 and the surface sheet 211 is higher than in the case where the entire core covering sheet 222 is formed of the low lignin region 251, and the surface sheet 211 can be prevented from peeling or floating from the absorbent body 220 during wearing. Further, when the amount of the adhesive is increased in order to increase the joining strength of the two sheets 211, 222, the sheet rigidity may be increased to lower the flexibility and the liquid permeability, but the above disadvantage is not caused.
The liquid-absorbent core 221 may contain mainly SAP particles and bleached fluff pulp, and may alternatively contain cellulose fibers, but does not contain the unbleached pulp fibers 242, and has a lower lignin content than the core cover sheet 222. Therefore, menstrual blood that has passed through the topsheet 211 and has been absorbed and diffused by the core covering sheet 222 tends to be quickly transferred so as to be absorbed into the liquid-absorbent core 221, which has a higher degree of hydrophilicity than the core covering sheet 222.
As described above, in the present embodiment, by positioning the plurality of high lignin regions 252 at the positions scattered in the low lignin regions 251 in the core covering sheet 222, the core covering sheet 222 has a natural appearance, is excellent in the concealing property of menstrual blood and the antibacterial property, and has appropriate bonding strength and liquid absorption property between the core covering sheet 222 and the surface sheet 211.
Further, the liquid-absorbent core 221 may be formed of only SAP particles. In this case, the absorbent body 220 includes a liquid-absorbent core 221 composed of only SAP particles and a core covering sheet 222 covering the liquid-absorbent core 221. In this case, the liquid retention is relatively low by providing the core covering sheet 222 with the low lignin region 251, while the liquid-absorbent core 221 is formed only of SAP particles having a high liquid-absorbing capacity, so that the entire absorbent body 220 can exhibit appropriate liquid-absorbing properties.
Since the low-lignin region 251 and the high-lignin region 252 are formed of the bleached pulp fibers 241 and the unbleached pulp fibers 242, the shape of the boundary between them is not clear, and they have at least a wave shape rather than a straight shape in a plan view. Thus, the required absorption area achieved by the low lignin region 251 can be maintained per unit width (e.g., 1.0mm) near the boundary between the low lignin region 251 and the high lignin region 252.
Referring again to fig. 15 and 16, an overlapping portion 223 in which both side edge portions 222a, 222b of the core covering sheet 222 are laminated on each other is located at a central portion in the transverse direction X of the absorbent body 220. Since the overlapped portion 223 is a portion where the core covering sheet 222 is stacked, the light brown color of the unbleached pulp fibers is visually recognized as darker than other portions of the absorbent body 220, and becomes an important point in design as a line extending in the longitudinal direction Y in an appearance view. The line extending in the longitudinal direction Y may be used as a mark indicating the center portion of the absorbent body 220 for positioning when the sanitary napkin 210 is attached to underwear or the like. Even when the liquid-absorbent core 221 absorbs a large amount of menstrual blood and the menstrual blood oozes out from both edges thereof, the leakage of menstrual blood to the outside from both side edges 220a and 220b of the absorbent body 220 can be effectively suppressed because the overlapping portion 223 including the relatively large amount of hydrophobic high lignin regions 252 is located outside in the longitudinal direction Y of both end edges of the liquid-absorbent core 221.
The core covering sheet 222 preferably has a formation index (Japanese: Di He い index) of 50 to 300. When the formation index of the core covering sheet 222 is less than 50, the pulp fibers are uniformly arranged at a high density, and the liquid permeability is lowered, and menstrual blood cannot be rapidly transferred to the liquid-absorbent core 221. On the other hand, if the formation index is more than 300, a portion having an extremely poor texture is formed, and the tensile strength is lowered, and there is a possibility that the portion is locally broken during use.
< method for measuring formation index >
The core cover sheet 222 was measured for formation index using a formation tester FMT-MIII, manufactured by nomuram co. The formation index of both surfaces of 3 specimens was measured under the conditions of a measurement area of 250mm × 180mm and a measurement time of 3 seconds/specimen, and the average value thereof was taken as a measurement value. The evenness index means that the smaller the measured value, the less uneven the texture.
Since the unbleached pulp fibers 242 have higher rigidity than the bleached pulp fibers 241, the softness is lower when the core-covering sheet is formed only of the unbleached pulp fibers 242, and the core-covering sheet cannot follow the movement of the surface sheet 211, and the core-covering sheet may be peeled off from the surface sheet 211, but the softness is not largely impaired by the high-lignin regions 252 being scattered in the low-lignin regions 251.
Thus, the core covering sheet 222 has desired flexibility, and specifically, the core covering sheet 222 has a wrinkle ratio (Japanese: クレープ ratio) of 7% to 20%. When the wrinkle ratio of the core covering sheet 222 is less than 7%, the rigidity of the core covering sheet 222 is relatively high and cannot follow the movement of the surface sheet 211, while when the wrinkle ratio is more than 20%, the core covering sheet 222 is too soft and may be broken during the manufacturing process or during the use.
< measurement method of wrinkling Rate >
The wrinkle ratio of the core covering sheet 222 was measured by an elongation in water method (Japanese: elongation in water method). The core covering sheet 222 was cut to 100mm × 100mm to prepare a measurement sample, the measurement sample was immersed in water for 10 seconds and then pulled up, and the wrinkling rate was calculated from the amount of change in dimension by the following equation. 3 measurements (n-3) were made, and the average value was taken as the measurement value.
Wrinkling rate (%) { (dimension after immersion in water)/(dimension before immersion in water) -1 } × 100
The surface sheet 211 can use a hydrophilic sheet containing cotton fibers (including organic cotton). When this sheet is used as the top sheet 211, the cushioning properties, skin-contactability, and liquid-absorbing properties are excellent. Further, by forming the liquid absorbent layer by the surface sheet 211 containing cotton fibers and the core covering sheet 222 having the high lignin region 252, the liquid holding property of the fibers is relatively small in the core covering sheet 222, and the surface sheet has high moisture absorption property, so that moisture in the absorbent body 220 can be absorbed in the surface sheet 211. This can suppress the generation of moisture between the sanitary napkin and the body, and suppress the internal stuffiness. Further, the top sheet 211 preferably has a multilayer structure made of hydrophilic fibers, and the layer on the skin-facing surface side is substantially made of cotton fibers. In this case, the cotton fiber can absorb moisture more effectively at a portion near the skin.
However, it is preferable that the klemm water absorption of the core covering sheet is higher than that of the surface sheet 211 containing cotton fibers. By making the klemm water absorption rate of the core covering sheet 222 higher than the klemm water absorption rate of the topsheet 211 positioned on the skin-facing surface side of the core covering sheet 222, menstrual blood absorbed and diffused in the topsheet 211 can be absorbed by the core covering sheet 222 and rapidly transferred to the liquid-absorbent core 221, and liquid remaining on the topsheet 211 can be effectively suppressed.
< method for measuring Klelm Water absorption >
The klemm water absorption of the core covering sheet 222 is measured in accordance with the klemm water absorption test (JIS-L1907, P8141). As the measuring instrument, a ruler, a stopwatch, a plastic container, and artificial urine (colored with blue No. 1) were used. A sheet obtained by cutting the core covering sheet 222 into a size of 25mm in width and 150mm in length was used as a sample (N ═ 3). First, artificial urine is put into a plastic container until the depth of the artificial urine reaches 10mm or more. Subsequently, the extracted test piece was fixed by a fixing chuck and set to be immersed in artificial urine at a depth of 5mm from the sample tip. The test piece was left in this state for 120 seconds (environment: temperature 20 ℃ C./humidity 60%). The artificial urine rises along the specimen, and the suck-up distance on the specimen is measured from the surface of the artificial urine. A longer pick-up distance indicates a higher klemm water absorption.
In addition, when a sheet containing cotton fibers is used as the topsheet and a tissue paper mainly composed of bleached pulp fibers is used as the core covering sheet located under the topsheet, menstrual blood cannot be rapidly transferred to the liquid-absorbent core because of high liquid retention. In the present embodiment, since the core covering sheet 222 has the high lignin region 252, the liquid retention property as a whole is low, and it can be said that menstrual blood can smoothly migrate downward.
As described above, the liquid-absorbent core 221 may alternatively include cellulose fibers including cellulose fibers such as cotton and pulp fibers, semi-synthetic cellulose fibers such as acetate fibers, and regenerated cellulose fibers such as rayon. Since the core covering sheet 222 also has cellulose fibers composed of bleached pulp fibers 241 and unbleached pulp fibers 242 as in the liquid-absorbent core 221, the affinity thereof is high, and the bonding strength is increased when the core covering sheet 222 and the liquid-absorbent core 221 are welded to each other in compressed grooves or the like located in the outer periphery of the absorbent body.
The liquid-absorbent core 221 may have a plurality of functional particles formed of activated carbon, zeolite, or the like and having an adsorption function for odor of body fluid such as menstrual blood. By providing the absorbent core 221 with odor-absorptive properties, the sanitary napkin 210 can be used and discarded more hygienically and cleanly in addition to the antibacterial properties of the core covering sheet 222.
In the present embodiment, since the plurality of high lignin regions 252 are located at positions scattered over the entire range of the core covering sheet 222 in the peripheral region constituted by the low lignin regions 251, the plurality of high lignin regions 252 are scattered not only in the 1 st wrapping portion 225 covering the skin-facing surface side of the absorbent body 220 in the core covering sheet 222 but also in the 2 nd wrapping portion 226 covering the non-skin-facing surface side of the absorbent body 220. Therefore, in the cross-sectional view, the low lignin regions 251 and the high lignin regions 252 are also located at positions alternating in the transverse direction X in the 2 nd coating portion 226.
It can be said that the high lignin region 252 has higher adhesion strength to the sheet than the low lignin region 251, and therefore the bonding strength of the core covering sheet to the back sheet 212 is superior to that in the case of using a normal core covering sheet not having the high lignin region 252. Therefore, it is not necessary to increase the weight per unit area of the adhesive agent in order to increase the bonding strength, and the sheet rigidity is not increased by the increase of the adhesive agent, which leads to a decrease in the followability to the absorbent body 220.
Since the entire core covering sheet 222 is light brown derived from a plant material such as wood, when artificial menstrual blood (5ml) is dropped onto the liquid-absorbent core 221 through the surface sheet 211, the a value, b value, and L value of the laa b color system (laa b color space, hereinafter abbreviated as "lab") are measured in the menstrual blood absorbing region observed from the skin-facing surface side and the menstrual blood non-absorbing region including the liquid-absorbent core 221. The weight per unit area used in example 1 without an intermediate sheet and of the core covering sheet was 14g/m 2In example 2, the sanitary napkin 210 having no intermediate sheet and the core covering sheet had a weight per unit area of 20g/m2The sanitary napkin 210. Further, in order to compare with examples 1 to 2, the core coating sheet had a core coating sheet containing a lignin component and an intermediate sheet containing no lignin component, and the weight per unit area of the core coating sheet was 14g/m2The sanitary napkin of comparative example 1, the sanitary napkin of comparative example 2 using a white core covering sheet containing no lignin component and cotton as a surface sheet, and the sanitary napkin of comparative example 1 using a white core containing no lignin componentIn the sanitary napkin of comparative example 3 in which the cover sheet and the topsheet were not cotton, the standard menstrual blood was dropped onto the liquid-absorbent core 221 via the topsheet, and the a value, b value and L value of the Lab color system were measured in the menstrual blood-absorbing region and the menstrual blood-non-absorbing region observed from the skin-facing surface side. The experimental results are shown in tables 8 to 10. Further, as the artificial menstrual blood, a liquid obtained by mixing appropriate amounts of ionic water, glycerin, sodium carboxymethylcellulose, sodium chloride, sodium bicarbonate, pigment Red No. 102, pigment Red No. 2, and pigment yellow No. 5 (each pigment is manufactured by Takara Shuzo Co., Ltd.) was used.
[ Table 8]
a value
Example 1 Example 2 Comparative example 1 Comparative example 2 Comparative example 3
Non-absorbent region 0.67 2.63 0.59 -0.75 -0.76
Absorbent region 49.64 49.10 52.97 51.52 55.45
Difference between the two 49.17 46.47 52.38 52.27 56.21
Evaluation of ○ ○ × × ×
(measurement method for color difference)
Color difference measurement was performed in accordance with JIS Z8722 using a color difference meter ZE6000 (standard white board [ X: 93.19, Y: 95.20, Z: 112.28], reflection measurement diameter 30mm, manufactured by japan electro-chromatic industries co. The measurement was performed 5 times for each sample, and the average of the measured values was defined as the L value, a value, and b value of each sample.
The a-value relates primarily to red and green, with red for larger values and green for smaller values. The green color is darker when it becomes negative. Referring to table 8, in the sanitary napkins of comparative examples 2 and 3, since the white core covering sheet was used, the a value in the non-absorbent region was negative, while the a value in the absorbent region was 50.0 or more, the difference between the two was large, and the red color in the absorbent region was conspicuous. On the other hand, in the sanitary napkins of examples 1-2, since the 1 st core covering sheet 222 is light brown, the a value in the non-absorbent region is 0.5 or more, which is a positive number, and the a value in the absorbent region is less than 50.0, the difference between the two is 50 or less, and the condition that the red color in the absorbent region is conspicuous can be suppressed. On the other hand, in the sanitary napkin of comparative example 1, the a value of the non-absorbent region is positive since the core covering sheet is light brown, but the a value of the absorbent region is more than 50 since the white intermediate sheet is used. Thus, the red color of the absorption region is more conspicuous. In view of the above, the a value of the non-absorption region is preferably 0.50. ltoreq. a value.ltoreq.10.00. The value a of the absorption region is preferably 50 or less. The difference between the absorption region and the non-absorption region is preferably 50 or less. Regarding the value of a, the sanitary napkins of examples 1 and 2 are preferable, and the sanitary napkins of comparative examples 1 to 3 are not preferable.
[ Table 9]
b value
Example 1 Example 2 Comparative example 1 Comparative example 2 Comparative example 3
Non-absorbent region 9.61 10.47 6.89 2.72 7.78
Absorbent region 23.25 26.61 29.69 27.49 31.47
Difference between the two 13.64 16.14 22.80 24.77 23.69
Evaluation of ○ ○ × × ×
The b-value relates primarily to yellow and blue, with yellow at higher values and blue at lower values. Referring to table 9, in the sanitary napkin of comparative example 2, since the white core covering sheet was used, the b value in the non-absorbent region was less than 7, the b value in the absorbent region was more than 27, the difference between the two was more than 20, the difference between the two was large, and the yellow color in the absorbent region was conspicuous. In the sanitary napkin of comparative example 3, since the white core covering sheet was used, the b value in the absorbent region was larger than 27, the difference between the two was large, and the yellow color in the absorbent region was conspicuous. On the other hand, in the sanitary napkins of examples 1-2, since the core covering sheet 222 is light brown, the b value in the non-absorbent region is 7 or more and 15 or less, the b value in the absorbent region is 30 or less, and the difference between the two is 20 or less, so that the yellow color in the absorbent region can be suppressed from becoming conspicuous. On the other hand, in the sanitary napkin of comparative example 1, a light brown core covering sheet was used, but since a white intermediate sheet was used, the b value of the non-absorbent region was less than 7 (blue color was observed when the b value was close to 0). Therefore, the color difference between the absorption region and the non-absorption region is large, and the color of the absorption region cannot be suppressed from being conspicuous. In view of the above, the b value of the non-absorption region is preferably 7. ltoreq. b value.ltoreq.15. The b value of the absorption region is preferably 30 or less. The difference between the absorption region and the non-absorption region is preferably 20 or less. Regarding the b value, the sanitary napkins of examples 1 and 2 are preferable, and the sanitary napkins of comparative examples 1 to 3 are not preferable.
The L value relates to the brightness of the color, with white at higher values and black at lower values. Referring to table 10, the L value is preferably 70 or more and 90 or less. Regarding the L value, the sanitary napkins of examples 1 and 2 are preferable, and the sanitary napkins of comparative examples 1 to 3 are not preferable.
[ Table 10]
Value of L
Example 1 Example 2 Comparative example 1 Comparative example 2 Comparative example 3
Non-absorbent region 90.26 84.15 91.18 93.43 94.18
Absorbent region 28.77 30.85 32.24 31.21 33.94
Difference between the two 61.49 53.30 58.94 62.22 60.24
Evaluation of ○ ○ × × ×
The entire core covering sheet 222 is light brown derived from a plant material such as wood, the absorber 220 is light brown, and the wing portions 218 are white. Therefore, the a value of the Lab color system was measured for the absorbent body 220 containing the liquid-absorbent core 221 and the wing portions 218 not containing the absorbent body 220. The weight per unit area used in example 1 without an intermediate sheet and of the core covering sheet was 14g/m2The sanitary napkin 210. In addition, for comparison with example 1, the sanitary napkins of comparative examples 1 to 3, each of which uses a core covering sheet not containing a lignin component, were also measured for the Lab color system for the absorbent body 220 including the liquid-absorbent core 221 and the wing portions 218 not including the absorbent body 220 in the same mannerand a value. The experimental results are shown in table 11. In addition, a standard white plate was covered on a sanitary napkin as a test piece and light was irradiated from below to measure the a value. This is to prevent the measurement result from varying depending on the color of the back surface side of the sanitary napkin due to the light transmission of the wing portions 218.
[ Table 11]
a value
Example 1 Comparative example 1 Comparative example 2 Comparative example 3
Absorbent body 0.59 -0.75 -0.67 -0.89
Wing part -0.64 -0.64 -0.56 -0.64
Difference between the two 1.23 0.11 0.11 0.25
Evaluation of ○ × × ×
As shown in Table 11, the difference between the two sanitary napkins of example 1 was 0.5 or more, and the difference between the two sanitary napkins of comparative examples 1 to 3 was less than 0.5. When the difference between the both is 0.5 or more, the boundary between the periphery of the absorbent body and the other region including the wing portions 218 is conspicuous, and therefore, the wearer or the caregiver can grasp the position of the absorbent body 220, which is preferable.
In the above-described embodiment, the liquid-absorbent core 121 does not contain a lignin component. However, the present invention is not limited thereto, and the liquid-absorbent core 221 may contain a lignin component.
< embodiment 2 of invention 2 >
Fig. 19 is a plan view of a sanitary napkin 210 according to embodiment 2 of the present invention 2, and fig. 20 (a) is a sectional view of embodiment 2 similar to fig. 15. Since the basic structure of the sanitary napkin 210 according to the present embodiment is the same as that of the sanitary napkin according to embodiment 1, only the differences will be described below.
In the present embodiment, the sanitary napkin 210 has a plurality of concave portions 260 that are recessed from the front sheet 211 toward the back sheet 212 in the liquid absorbent layer 213, and compressed grooves 270 that extend discontinuously in a ring shape so as to surround the plurality of concave portions 260. The concave portion 260 has a bottom and is located at a position separated from each other in the longitudinal direction Y and the lateral direction X in a plan view. The concave portion 260 has various known shapes such as a circle, an ellipse, a triangle, and a rectangle, in addition to the illustrated form.
The concave portions 260 can be formed by, for example, pressure and heat treatment. Specifically, in a known embossing process, the absorbent body 220 can be formed by pressing an embossing pin from the surface sheet 211 side and compressing the same together with the surface sheet 211. Thus, the thin portions 261 where the concave portions 260 are located in the absorber 220 have a higher fiber density than the thick portions 262 located at the periphery thereof where the concave portions 260 are not present. Since the core covering sheet 222 has a plurality of high lignin regions 252, the liquid diffusibility is relatively low, and the liquid may not be diffused and absorbed into the entire liquid-absorbent core 221.
In the present embodiment, by providing the plurality of concave portions 260 extending into the liquid-absorbent core 221, bodily fluids can be directly retained in the concave portions 260, the surface area of the liquid-absorbent core 221 that indirectly contacts menstrual blood through the topsheet 211 and the core covering sheet 222 is large, and menstrual blood can be rapidly absorbed and retained in the liquid-absorbent core 221 by the two sheets 211, 222. Further, since the thin portions 261 in which the concave portions 260 are located have a higher fiber density than the thick portions 262, the bodily fluid accumulated in the concave portions 260 can be sucked and absorbed and held downward more quickly.
Fig. 20 (b) is a sectional view similar to fig. 20 (a) showing a modification of the sanitary napkin 210 according to embodiment 2.
Referring to fig. 20 (b), the concave portion 260 of the present modification is formed by an opening penetrating the liquid absorbent layer 213 in the thickness direction Z. Since the liquid-impermeable back sheet 212 is positioned on the bottom surface of the concave portion 260, the body fluid accumulated in the through-opening is absorbed and held by the absorbent body 220 through the peripheral wall of the opening without leaking to the outside.
< embodiment 3 of the invention 2 >
Fig. 21 shows an example of a usage example of the absorbent article of the invention 2, in which the absorbent body 220 is applied to a disposable diaper (absorbent article) 280. The disposable diaper 280 is shown in a state in which side seams joining both side edge portions of the front waist pad 284 and the back waist pad 285 are peeled off and the disposable diaper 280 is stretched in the transverse and longitudinal directions.
The disposable diaper 280 has a front waist region 281, a rear waist region 282, and a crotch region 283 between the front waist region 281 and the rear waist region 282. The diaper 280 further includes a front waist pad 284 defining a part of the front waist region 281 and the crotch region 283, a back waist pad 285 defining a part of the back waist region 282 and the crotch region 283, and a liquid-absorbent structure 286 extending in the longitudinal direction on the skin-facing surface side of the front waist pad 284 and the back waist pad 285, and the front waist pad 284 and the back waist pad 285 are joined to each other with their both side edge portions overlapped with each other by a plurality of seams arranged at intervals in the longitudinal direction to define a waist opening and a pair of leg openings. The absorbent body 220 extends from the crotch region 283 to the front waist region 281 and the back waist region 282 in the absorbent structure 286.
The diaper 280 is a so-called pants type diaper in which both side edges of a front waist region 281 and a rear waist region 282 are joined in advance, and similarly to the sanitary napkin 210, the absorbent body 220 is composed of a liquid-absorbent core 221 and a core covering sheet 222 covering the liquid-absorbent core 221, and the core covering sheet 222 includes a peripheral region composed of a low-lignin region 251 and a plurality of high-lignin regions 252 dispersed in the peripheral region. In the absorbent body 220, when the inner surface and/or the outer surface of the diaper 280 is observed, the light brown color of the core covering sheet 222 is seen through, so that the product impression of natural feeling using natural materials can be given, and the antibacterial property is excellent, and body fluid such as urination and loose stool can be rapidly transferred from the core covering sheet 222 to the liquid-absorbent core 221. The absorbent article of the present invention may be not only a pants-type diaper but also an open-type diaper.
In each embodiment, a separate sheet having bulkiness and excellent cushioning properties may be disposed between the surface sheet 211 and the core covering sheet 222. Since the independent sheet is joined to the surface sheet 211, it can be said that the independent sheet is substantially a part of the surface sheet 211.
In addition, the core covering sheet 222 may be formed of two sheets of fiber nonwoven fabric, a sheet including the bleached pulp fibers 241 and the unbleached pulp fibers 242 may be used as the core covering sheet positioned on the skin-facing surface, and a sheet including only the bleached pulp fibers 241 may be used as the core covering sheet positioned on the non-skin-facing surface. In such a sanitary napkin, the absorbent body 220 is light brown when visually recognized from the skin-facing surface, and the absorbent body 220 is white when visually recognized from the non-skin-facing surface. Therefore, when the opening of the package having a plurality of sanitary napkins is formed on the side other than the skin-facing surface, the user can be given an impression of a clean article, while when the opening of the package is formed on the side opposite the skin, the user can be given an impression of a skin-friendly article using natural materials.
The embodiments of the present invention disclosed above can be adopted in a disassembled or combined manner with each other.
As long as it is not particularly described, various known materials generally used in this field can be used without limitation, in addition to the materials described in the present specification, for each constituent member constituting the absorbent articles 210 and 280. In addition, the terms "1 st" and "2 nd" used in the present specification and claims are used only for distinguishing the same elements, positions, and the like.
< invention 3 >
< embodiment 1 of the 3 rd invention >
The following embodiment 3 of the invention relates to the absorbent article shown in the drawings, and includes not only the indispensable structure of the invention but also optional and preferable structures. Hereinafter, an embodiment of a sanitary napkin 310 as an example of an absorbent article of the present invention will be described with reference to the drawings. The sanitary napkin 310 has a longitudinal direction Y, a transverse direction X, and a thickness direction Z.
Referring to fig. 22 to 24, the sanitary napkin 310 has a longitudinal center line P bisecting the dimension in the width direction thereof and a transverse center line Q bisecting the dimension in the longitudinal direction thereof, and includes a skin-facing surface (inner surface) side and a non-skin-facing surface (outer surface) side opposite thereto, a convex curved first end edge 310a and second end edge 310b, a convex curved first side edge 310c and second side edge 310d at a central portion where the transverse center line Q is located, a liquid-permeable front sheet 311 positioned on the skin-facing surface side, a liquid-impermeable back sheet 312 positioned on the non-skin-facing surface side, and a liquid-absorbent body 320 positioned between the two sheets 311, 312. The top sheet 311 and the absorbent body 320 are joined to each other by a known joining means such as a hot melt adhesive to form the liquid absorbent layer 313.
Further, although not shown, an intermediate sheet made of a relatively bulky fibrous nonwoven fabric may be disposed between the top sheet 311 and the absorbent member 320 in order to improve the flexibility of the sanitary napkin 310. In order to suppress leakage of bodily fluids, a leakage preventing sheet, preferably having air permeability and made of liquid impermeable fibrous nonwoven fabric or plastic film, may be disposed between the absorbent body 320 and the back sheet 312.
The absorbent body 320 has a 1 st end edge 320a opposed to the 1 st end edge 310a, a 2 nd end edge 320b opposed to the 2 nd end edge 310b, and a 1 st side edge 320c and a 2 nd side edge 320d extending in the longitudinal direction between the 1 st end edge 320a and the 2 nd end edge 320 b. The front sheet 311 and the back sheet 312 extend outward from the outer periphery of the absorbent body 320, and a pair of side sheets 314 extending in the longitudinal direction Y so as to face each other in the lateral direction are arranged on the skin-facing surface side of the front sheet 311. The pair of side sheets 314 are joined to the front sheet 311 by side joining portions (not shown) formed by a known adhesive means or welding means. Although not shown, in the side sheet 314, in order to form a leakage preventing wall that rises toward the body side in a worn state, an elastic material extending in the longitudinal direction Y may be disposed so as to be contractible in an extended state on the side sheet 314. The side joining portion for fixing the side sheet 314 may be a seal line extending in the longitudinal direction Y and having design elements such as a pattern and a geometric pattern.
The sanitary napkin 310 has both end portions 316 formed by the front sheet 311, the back sheet 312 and the side sheets 314 and extending in the transverse direction X outside the longitudinal direction Y of the 1 st end edge 320a and the 2 nd end edge 320b of the absorbent body 320, and both side edge portions 317 extending in the longitudinal direction Y outside the transverse direction X of the 1 st side edge 320c and the 2 nd side edge 320d of the absorbent body 320. The flaps 318, which are formed by the parts of the both side edges 317, protruding outward in the transverse direction X, are located in the central part in the longitudinal direction Y of the sanitary napkin 310. The sheets 311, 312, and 314 stacked on each other are joined to each other by a peripheral seal portion 319 located along the outer peripheral edge of the sanitary napkin 310.
Referring to fig. 23, a plurality of fastening regions 330 are disposed on the back side of the sanitary napkin 310. The plurality of fastening regions 330 are used for fastening the sanitary napkin 310 to clothing such as underwear, and the plurality of fastening regions 330 are formed by a plurality of thread-like applied adhesives or pressure-sensitive adhesives extending in the longitudinal direction Y. The fastening region 330 has a central region 331 extending in the longitudinal direction Y in a region overlapping the absorbent body 320 and side regions 332 located at the wings 318. The fixing region 330 is covered with a spacer (not shown) made of a plastic film.
The surface sheet 311 may be made of various liquid-permeable nonwoven fabrics of fibers, for example, having a basis weight of about 15g/m 2～45g/m2The nonwoven fabric of air-through fibers, the porous plastic film, the laminate of the above materials, and the like. The back sheet 312 may be formed of a liquid-impermeable and moisture-permeable plastic film, a liquid-impermeable fibrous nonwoven fabric, a laminate of the above materials, or the like. The side sheet 314 can be the same sheet as the front sheet 311. However, in order to effectively prevent the side leakage of body fluid, it is preferable to use a sheet having hydrophobicity or waterproofness.
As the front sheet 311, a sheet having an uneven surface side can be used. The surface of the sheet is formed by a plurality of concave portions and a plurality of convex portions alternately arranged in the longitudinal direction Y or the transverse direction X, and as a method for forming the plurality of convex portions and concave portions, for example, a method for forming a dense portion and a bulky portion by controlling the amount of fibers, a method for forming concave portions by embossing, a method for forming concave portions into a concave-convex shape, and the like are considered. The fibers are arranged in the convex portion and the concave portion so as to be sparse one and dense the other in such a manner that the fiber densities are different from each other. The joining strength can be further improved by joining the portion where the fibers are sparsely arranged (the 1 st portion) and the high lignin region 352 of the core covering sheet 322 described later, while the liquid absorption can be further improved by joining the portion where the fibers are densely arranged (the 2 nd portion) and the low lignin region 351.
Even when menstrual blood is repeatedly excreted for a relatively short period of time, the menstrual blood can be temporarily accumulated in the concave portions, and leakage of menstrual blood from the surface of the front sheet 311 and between the front sheet 311 and the core covering sheet 322 can be suppressed. Further, it is preferable that a part of the concave portion of the surface sheet 311 is substantially (continuously or discontinuously) surrounded by a compressed portion in which compressed grooves are formed, a compressed concave portion formed by embossing, or the like. In this case, the body fluid accumulated in the concave portion can be prevented from leaking in the lateral direction X and the longitudinal direction Y. In addition, in the case where the surface of the surface sheet is uneven, the core covering sheet 322 of light brown color is visually recognized as darker in color than the convex portion in the concave portion in the surface view, and therefore, a decorative effect by gradation of color can be produced.
The outer peripheral seal portion 319 can be bonded with an adhesive, bonded with a known welding means such as ultrasonic welding, thermal welding, laser welding, or high-frequency welding, or bonded with embossing, either singly or in combination. The sheets 311, 312, and 314 stacked in the thickness direction Z are bonded to each other with an adhesive such as a hot melt adhesive. Examples of the method for applying the hot melt adhesive include various known coating methods such as spiral coating, coater coating, curtain coater coating, and spray coating.
Referring to fig. 24 and 25, the absorbent body 320 includes a liquid-absorbent core 321 formed by mixing superabsorbent polymer particles (SAP) and cellulose fibers such as fluffed wood pulp and rayon fibers and shaped into a predetermined shape, and a liquid-permeable core cover sheet 322 for wrapping the entire liquid-absorbent core 321 to improve shape retention and liquid diffusion properties of the absorbent body 320.
The core covering sheet 322 has a dimension in the longitudinal direction Y larger than that of the liquid-absorbent core, and has side edge portions 322a, 322b which overlap each other on the bottom side of the central portion in the transverse direction X of the liquid-absorbent core 321 so as to wrap the entire liquid-absorbent core 321. By stacking the side edges 322a, 322b, an overlapping portion 323 is formed in the center portion in the transverse direction X of the absorbent body 320, and the overlapping portion 323 is formed by stacking the side edges 322a, 322b extending in the longitudinal direction Y.
The core covering sheet 322 has a 1 st covering portion 325 covering the skin-facing surface side of the liquid-absorbent core 321, and a 2 nd covering portion 326 covering the non-skin-facing surface side of the liquid-absorbent core 321. In the present embodiment, the core covering sheet 322 is formed of one continuous sheet, but may be formed of a 1 st core covering sheet forming the 1 st covering portion 325 and a 2 nd core covering sheet independent of the 1 st core covering sheet and forming the 2 nd covering portion 326.
Referring to fig. 26, the core covering sheet 322 is formed of various well-known fibrous nonwoven fabrics or tissue papers, mainly pulp fibers 340. The pulp fibers 340 of the core cover sheet 322 have bleached pulp fibers 341 that have been delignified and unbleached pulp fibers 342 that have not been delignified. Here, the pulp fiber 340 contains, in addition to a wood pulp fiber obtained from a conifer or a hardwood tree as a raw material, a non-wood pulp fiber obtained from cotton linter, abaca, hibiscus hemp, straw, bamboo, or banana as a raw material.
The core covering sheet 322 may have a multilayer structure including, for example, a 1 st layer (upper layer or lower layer) composed of regenerated cellulose fibers such as rayon fibers and hydrophilic fibers such as semi-synthetic cellulose fibers, and a 2 nd layer (lower layer or upper layer) composed of unbleached pulp fibers 342 that have not been subjected to delignification treatment. In this case, even when the 2 nd layer has a sea-island structure composed of the low lignin regions 351 and the high lignin regions 352 as described later, the body fluid can be sufficiently diffused in the 1 st layer, and thus the unevenness in the diffusion of the body fluid in the entire core covering sheet 322 can be suppressed. This can suppress a decrease in the adhesiveness between the core covering sheet 322 and the topsheet 311 even after a plurality of times of absorption of bodily fluids, and can maintain a preferable liquid-absorbing property.
The pulp fiber 340 is generally a bleached pulp fiber 341 obtained by subjecting a raw material chip to a raw material chip treatment step, then to a cooking step (step 1 of delignification treatment) of adding a chemical to the raw material chip and boiling the chip at high temperature and high pressure to cook lignin, a screening step of removing foreign matters in the pulp, an oxygen exposure step (step 2 of delignification treatment) of decomposing lignin remaining in the cooking step with oxygen, and a bleaching step of bleaching the pulp with various chemicals. The unbleached pulp fibers 342 are obtained by only passing through the cooking step and the screening step, which are the 1 st stage of the delignification treatment, among the above-described steps, and are obtained by performing the delignification treatment to a certain extent.
The lignin content of the unbleached pulp fiber 342 is 0.2-10.0%.
The lignin content of the unbleached pulp fibers 342 was measured by the following method.
< method for measuring Lignin content >
Quantification of ADF
Reagent: agent obtained by dissolving 10g of acidic detergent solution (Hexadecacyltrimethylammonium Bromide (Hexadecacyltrimethylammonium Bromide) in 500mL of 1N sulfuric acid >
Acetone (II)
Decalin as an antifoaming agent (alternative)
< measurement procedure >
A sample (300 g) was weighed, placed in a 50mL Erlenmeyer flask, and 30mL of an acidic detergent solution was added. Covered with aluminum foil, and the Erlenmeyer flask was placed in boiling water to decompose the product for 60 minutes. After the decomposition, it was transferred to a glass fiber filter paper (GA-200) -laid Gu's crucible and subjected to suction filtration, and the residue was washed with hot water and acetone. After air drying, thermal drying is carried out. The ash obtained by removing ash by taking a constant amount after drying is ADF, but ash obtained by quantifying lignin cannot be used for this purpose.
Lignin quantification
Reagent: 72% sulfuric acid
< measurement procedure >
A few drops of 72% sulfuric acid were dropped into the above-described dry gouge crucible to wet the whole, and then about twice the amount of ADF was added, and the sulfuric acid was appropriately added every hour and left for 3 to 4 hours. Thereafter, the reaction mixture was subjected to suction filtration and washed with hot water until the furnace liquid showed no acidity. After air drying, heat drying was carried out and a constant amount was taken. Ashing was performed at 550 ℃ in a Gu-Shi crucible to determine ash content.
The 1 st coating portion 325 of the core covering sheet 322 has a low lignin region (lignin low content region) 351 having a relatively low content of lignin components and a high lignin region (lignin high content region) 352 having a relatively high content of lignin components compared to the low lignin region 351. The low lignin regions 351 are formed primarily by the aggregation of bleached pulp fibers 341 and the high lignin regions 352 are formed primarily by the aggregation of unbleached pulp fibers 342. In a plan view of the 1 st coating portion 325 of the core covering sheet 322, the low lignin regions 351 are peripheral regions located in a relatively large range on the outer surface of the core covering sheet 322, while the high lignin regions 352 are disposed so as to be scattered in the low lignin regions 351. In addition, since the core covering sheet 322 or at least the 1 st covering portion 325 has such an arrangement, the entire core covering sheet 322 or at least the 1 st covering portion may have a sea-island structure in which the low lignin region 351 is a sea and the high lignin region 352 is an island.
Since the core covering sheet 322 has a plurality of high lignin regions 352, it has a light brown color derived from a plant material such as wood as a whole. Since the sheets 311, 312, and 314 other than the core covering sheet 322 are white as a whole by kneading a white pigment such as titanium dioxide into the constituent fibers, the core covering sheet 322 can be easily visually recognized through the other sheets 311, 312, and 314 in the front view and/or the back view of the sanitary napkin 310.
The core covering sheet 322 of the present embodiment is formed by interlacing a mixture of bleached pulp fibers 341 and unbleached pulp fibers 342 in a paper making process thereof into a sheet, and since the bleached pulp fibers 341 are mainly disposed in the low-lignin region 351 and the unbleached pulp fibers 342 are mainly disposed in the high-lignin region 352, the boundary between the two regions 351 and 352 is not clear and cannot be clearly distinguished. As a method for forming the high-lignin regions 352 so as to be dispersed in the low-lignin regions 351 over the entire outer surface of the core covering sheet 322, for example, a method of mixing the pulp fibers 341 and 342, a mixing ratio, a conveying speed of a conveyor at the time of production, a nozzle diameter at the time of depositing the pulp fibers 340 on the conveyor by air ejected from a plurality of nozzles, an air volume of blown air, an air velocity, and the like may be appropriately adjusted.
Since the two regions 351 and 352 are formed by adjusting various conditions of the production process, the unbleached pulp fibers 342 may be contained in part of the low lignin region 351 and the bleached pulp fibers 341 may be contained in the high lignin region 352. Therefore, the low-lignin region 351 and the high-lignin region 352 are not formed only of the bleached pulp fibers 341 and the unbleached pulp fibers 342, respectively, but may contain other fibers other than pulp fibers, for example, the content of the bleached pulp fibers 341 in the pulp fibers of the low-lignin region 351 is 50% to 100%, and the content of the unbleached pulp fibers 342 in the pulp fibers of the high-lignin region 352 is 50% to 100%.
The high lignin region 352 is a region having a higher content of lignin component than the low lignin region 351 which is a peripheral region of the core covering sheet 322, and therefore the high lignin region 352 can be formed without using a sheet in which the bleached pulp fibers 341 and the unbleached pulp fibers 342 are mixed. For example, the high lignin region 352 having a higher lignin content than the surrounding region can be formed by allowing a liquid containing a lignin component to dispersedly infiltrate into a fibrous nonwoven fabric sheet composed of rayon fibers or synthetic fibers.
Since the core covering sheet 322 has the plurality of high lignin regions 352 mainly composed of the unbleached pulp fibers 342, it has a light brown color (wood color) derived from a plant material in a surface view, as compared with the case of using a core covering sheet composed of only unbleached pulp fibers, and can give an impression that a wearer or a wearer assistant is a product which is mild to the skin and is made of a natural material. Further, since the core covering sheet 322 has a light brown color, the degree of redness of menstrual blood is suppressed when the menstrual blood excreted passes through the surface sheet 311 and is absorbed and held by the absorbent body 320. This can suppress aversion caused by direct visual recognition of menstrual blood, and can alleviate mental uneasiness caused by visual recognition of the redness of menstrual blood for example in wearers of menstrual onset. Further, since the lignin component has an antibacterial action, the propagation of mixed bacteria after use can be suppressed and the disposal can be performed hygienically.
The core covering sheet 322 preferably has a lignin content of 0.2% to 10% in order to exhibit its natural appearance, suppression of redness of menstrual blood, and a certain antibacterial effect. When the content of the lignin component in the core covering sheet 322 is less than 0.2%, the color of the light brown color of the core covering sheet 322 may be so light that it cannot be visually distinguished from the other white sheets 311, 312, and 314. On the other hand, when the content of the lignin component in the core covering sheet 322 is greater than 10%, the chroma of the lignin component is deep, and the natural appearance of the natural material may be impaired, and the redness of menstrual blood may be difficult to visually recognize, and the menstrual blood volume may not be accurately grasped.
In general, the core covering sheet has not only the function of retaining the shape of the liquid-absorbent core but also the function of absorbing and diffusing body fluid having passed through the topsheet and transferring the body fluid to the liquid-absorbent core, and therefore, a hydrophilic sheet is preferably used. Since the unbleached pulp fibers 342 in the high lignin region 352 contain a large amount of lignin component, the degree of hydrophilicity is low, and it can be said that the fibers are relatively hydrophobic, and therefore, for example, when the entire 1 st coating portion 325 is formed of the high lignin region 352, menstrual blood that has permeated the surface sheet 311 cannot be absorbed and retained in the high lignin region 352, and menstrual blood cannot be transferred to the liquid-absorbent core 321 quickly.
Referring to fig. 27, since the 1 st cladding portion 325 of the core covering sheet 322 has the low-lignin regions 351 and the plurality of high-lignin regions 352 scattered around the low-lignin regions 351, the two regions 351, 352 appear alternately in the transverse direction X in the cross-sectional view. Since the high lignin regions 352 are arranged so as to be scattered in the low lignin region 351, it can be said that the low lignin regions 351 and the high lignin regions 352 are alternately arranged not only in the lateral direction X but also in the longitudinal direction Y.
By positioning the low-lignin regions 351 and the high-lignin regions 352 at alternating positions in the lateral direction X and the longitudinal direction Y in the cross-sectional view of the 1 st coating portion 325 in this way, menstrual blood that has permeated the top sheet 311 in the hydrophilic low-lignin regions 351 can be absorbed and held by the liquid-absorbent core 321 by being absorbed and transferred quickly, and a desired absorption rate can be obtained.
In addition, in the hydrophilic low-lignin region 351, there is a possibility that menstrual blood is absorbed and the bleached pulp fibers are swollen, so that the bonded portions are peeled off at the bonded interface between the surface sheet 311 and the core covering sheet 322 by the hot melt adhesive, and the bonding strength is lowered. On the other hand, since the high lignin region 352 is less hydrophilic and hydrophobic than the low lignin region 351, it is less likely to absorb menstrual blood and swell, and the bonded portion does not peel off, and the bonding strength at the bonding interface between the core covering sheet 322 and the surface sheet 311 is higher than that of the low lignin region 351.
Therefore, the core covering sheet 322 has higher bonding strength with the surface sheet 311 as compared with the case where the entire core covering sheet 322 is formed of the low lignin regions 351, and the surface sheet 311 can be prevented from peeling or floating from the absorbent body 320 during wearing. Further, when the amount of the adhesive is increased in order to increase the joining strength of the two sheets 311, 322, the sheet rigidity may be increased to lower the flexibility and liquid permeability, but the above disadvantage is not caused.
The liquid-absorbent core 321 mainly contains SAP particles and bleached fluff pulp, and may alternatively contain cellulose fibers, but does not contain the unbleached pulp fibers 342, and has a lower lignin content than the core cover sheet 322. Therefore, menstrual blood that has passed through the topsheet 311 and has been absorbed and diffused by the core-covering sheet 322 tends to be rapidly transferred so as to be absorbed into the liquid-absorbent core 321, which has a higher degree of hydrophilicity than the core-covering sheet 322.
As described above, in the present embodiment, by positioning the plurality of high lignin regions 352 in the core covering sheet 322 at positions scattered over the low lignin regions 351, the core covering sheet 322 has a natural appearance, is excellent in the concealing property of menstrual blood and the antibacterial property, and has appropriate bonding strength and liquid absorption property between the core covering sheet 322 and the surface sheet 311.
Further, the liquid-absorbent core 321 may be formed of only the SAP particles. In this case, the absorbent body 320 includes a liquid-absorbent core 321 composed of only SAP particles, and a core-covering sheet 322 covering the liquid-absorbent core 321. By providing the core covering sheet 322 with the low lignin region 351, the liquid retention is relatively low, while by forming the liquid-absorbent core 321 only with SAP particles having a high liquid-absorbing capacity, the entire absorbent body 320 can exhibit appropriate liquid-absorbing properties.
Since the low lignin region 351 and the high lignin region 352 are formed by the bleached pulp fibers 341 and the unbleached pulp fibers 342, the shape of the boundary between them is not obvious, and they have at least a wave shape in a plan view rather than a straight shape. Thus, the required absorption area achieved by the low lignin region 351 can be maintained per unit width (e.g., 1.0mm) near the boundary between the low lignin region 351 and the high lignin region 352.
Referring again to fig. 24, an overlapping portion 323 where both side edge portions 322a, 322b of the core covering sheet 322 are stacked on each other is located at a central portion in the transverse direction X of the absorbent body 320. Since the overlapping portion 323 is a portion where the core covering sheet 322 is stacked, the light brown color of the unbleached pulp fibers is visually recognized as darker than other portions of the absorbent body 320, and becomes an important point in design as a line extending in the longitudinal direction Y in an appearance view. The line extending in the longitudinal direction Y may be used as a mark indicating the center portion of the absorbent body 320 for positioning when the sanitary napkin 310 is attached to underwear or the like. Even when the liquid-absorbent core 321 absorbs a large amount of menstrual blood and the menstrual blood oozes out from both edges thereof, the leakage of menstrual blood to the outside from both edges 320a and 320b of the absorbent body 320 can be effectively suppressed because the overlapping portion 323 including the relatively large amount of hydrophobic high lignin regions 352 is located outside in the longitudinal direction Y of both edges of the liquid-absorbent core 321.
The core covering sheet 322 preferably has a formation index of 50 to 300. When the formation index of the core covering sheet 322 is less than 50, the pulp fibers are uniformly arranged at a high density, and the liquid permeability is lowered, so that menstrual blood cannot be rapidly transferred to the liquid-absorbent core 321. On the other hand, if the formation index is more than 300, a portion having an extremely poor texture is formed, and the tensile strength is lowered, and there is a possibility that the portion is locally broken during use.
< method for measuring formation index >
The formation index of the core covering sheet 322 was measured using a formation tester FMT-MIII manufactured by nomuram corporation. The formation index of both surfaces of 3 specimens was measured under the conditions of a measurement area of 250mm × 180mm and a measurement time of 3 seconds/specimen, and the average value thereof was taken as a measurement value. The evenness index means that the smaller the measured value, the less uneven the texture.
Since the unbleached pulp fibers 342 are higher in rigidity than the bleached pulp fibers 341, the softness is lower when the core-covering sheet is formed only of the unbleached pulp fibers 342, and the core-covering sheet cannot follow the movement of the surface sheet 311, and there is a possibility that the core-covering sheet is peeled from the surface sheet 311, but the high-lignin regions 352 are scattered in the low-lignin regions 351, and the softness is not largely impaired.
Thus, the core covering sheet 322 has desired softness, and specifically, the core covering sheet 322 has a wrinkle ratio of 7% to 20%. When the crinkling ratio of the core covering sheet 322 is less than 7%, the rigidity of the core covering sheet 322 is relatively high and cannot follow the movement of the surface sheet 311, while when the crinkling ratio is more than 20%, the core covering sheet 322 is too soft and may be broken during the production process or the use process.
< measurement method of wrinkling Rate >
The core cover sheet 322 was measured for crepe by the elongation in water method. The core covering sheet 322 was cut to 100mm × 100mm to prepare a measurement sample, the measurement sample was immersed in water for 10 seconds and then pulled up, and the wrinkling rate was calculated from the amount of change in dimension by the following equation. 3 (n is 3) measurements were made, and the average value was taken as the measurement value.
Wrinkling rate (%) { (dimension after immersion in water)/(dimension before immersion in water) -1 }. times.100
The surface sheet 311 can use a hydrophilic sheet containing cotton fibers (including organic cotton). When this sheet is used as the topsheet 311, the sheet is excellent in cushioning properties, skin contact properties, and liquid absorption properties. Further, by forming the liquid absorbent layer by the surface sheet 311 containing cotton fibers and the core covering sheet 322 having the high lignin regions 352, the liquid retention of the fibers in the core covering sheet 322 is relatively small, while the surface sheet has high moisture absorbency, and therefore moisture in the absorbent body 320 can be absorbed in the surface sheet 311. This can suppress the generation of moisture between the sanitary napkin and the body, thereby suppressing the interior stuffiness.
However, it is preferable that the klemm water absorption of the core covering sheet is higher than that of the surface sheet 311 containing cotton fibers. By setting the klemm water absorption rate of the core covering sheet 322 higher than the klemm water absorption rate of the topsheet 311 positioned on the skin-facing surface side of the core covering sheet 322, menstrual blood absorbed and diffused in the topsheet 311 can be absorbed by the core covering sheet 322 and rapidly transferred to the liquid-absorbent core 321, and liquid remaining on the topsheet 311 can be effectively suppressed.
< method for measuring Klelm Water absorption >
The measurement of the gram water absorption of the core covering sheet 322 was carried out in accordance with the gram water absorption test (JIS-L1907, P8141). As the measuring instrument, a ruler, a stopwatch, a plastic container, and artificial urine (colored blue No. 1) were used. A sheet obtained by cutting the core covering sheet 322 into a size of 25mm in width and 150mm in length was used as a sample (N: 3). First, artificial urine is put into a plastic container until the depth of the artificial urine reaches 10mm or more. Subsequently, the extracted test piece was fixed by a fixing chuck and set to be immersed in artificial urine at a depth of 5mm from the sample tip. The test piece was left in this state for 120 seconds (environment: temperature 20 ℃ C./humidity 60%). The artificial urine rises along the specimen, and the suck-up distance on the specimen is measured from the surface of the artificial urine. A longer pick-up distance indicates a higher klemm water absorption.
In addition, when a sheet containing cotton fibers is used as the topsheet and a tissue paper mainly composed of bleached pulp fibers is used as the core covering sheet located under the topsheet, menstrual blood cannot be rapidly transferred to the liquid-absorbent core because of high liquid retention. In the present embodiment, since the core covering sheet 322 has the high lignin region 352, the liquid retention property as a whole is low, and it can be said that menstrual blood can smoothly migrate downward.
In this case, the layer (upper layer) on the skin-facing surface side is preferably substantially formed of cotton fibers. In this case, the cotton fiber can absorb moisture more effectively at a portion near the skin.
The top sheet 311 may have a multilayer structure, and a layer (upper layer) on the skin-facing surface side may be formed mainly of cotton fibers, and a layer (lower layer) on the non-skin-facing surface side may be formed mainly of hydrophobic synthetic resin fibers. In this case, the klemm water absorption rate of the surface sheet 311 is lower than that of the core covering sheet 322 regardless of whether the surface sheet 311 contains water-absorbent cotton fibers on the skin side. By setting the klemm water absorption rate of the top sheet 311 lower than the klemm water absorption rate of the core covering sheet 322, the body fluid can be diffused in the core covering sheet 322 located closer to the absorbent body 320 than the surface of the sanitary napkin 310 without being diffused in the body fluid, and the body fluid absorbed in the absorbent body 320 can be suppressed from flowing back (getting wet) to the surface side.
As described above, the liquid-absorbent core 321 may alternatively include cellulose fibers including cellulose fibers such as cotton and pulp fibers, semi-synthetic cellulose fibers such as acetate fibers, and regenerated cellulose fibers such as rayon. Since the core-covering sheet 322 also includes cellulose fibers composed of bleached pulp fibers 341 and unbleached pulp fibers 342, as in the liquid-absorbent core 321, the affinity thereof is high, and the bonding strength is increased when the core-covering sheet 322 and the liquid-absorbent core 321 are welded to each other in compressed grooves or the like located on the outer periphery of the absorbent body.
The liquid-absorbent core 321 may have a plurality of functional particles formed of activated carbon, zeolite, or the like and having an odor-adsorbing function of body fluid such as menstrual blood. By providing the liquid-absorbent core 321 with odor-absorptive properties, the sanitary napkin 310 can be used and discarded in a more sanitary and clean manner in addition to the antibacterial properties of the core covering sheet 322.
In the present embodiment, since the plurality of high lignin regions 352 are located at positions scattered over the peripheral region composed of the low lignin regions 351 over the entire range of the core covering sheet 322, the plurality of high lignin regions 352 are scattered not only over the 1 st wrap 325 covering the skin-facing surface side of the absorbent body 320 in the core covering sheet 322 but also over the 2 nd wrap 326 covering the non-skin-facing surface side of the absorbent body 320. Therefore, in the cross-sectional view shown in fig. 24, the low lignin regions 351 and the high lignin regions 352 are also located at alternating positions in the lateral direction X in the 2 nd coating portion 326.
It can be said that the high lignin regions 352 have higher adhesive strength to the sheet than the low lignin regions 351, and therefore the bonding strength between the core covering sheet and the back sheet 312 is superior to that in the case of using a normal core covering sheet not having the high lignin regions 352. Therefore, it is not necessary to increase the weight per unit area of the adhesive in order to increase the bonding strength, and the sheet rigidity is not increased by the increase of the adhesive, which leads to a decrease in the conformability to the absorbent body 320.
< embodiment 2 of invention 3 >
Fig. 28 is a plan view of a sanitary napkin 310 according to embodiment 2 of fig. 3, and fig. 29 (a) is a sectional view of embodiment 2 similar to fig. 24. Since the basic structure of the sanitary napkin 310 of the present embodiment is the same as that of the sanitary napkin of embodiment 1, only the differences will be described below.
In the present embodiment, the sanitary napkin 310 has a plurality of concave portions 360 recessed from the front sheet 311 toward the back sheet 312 side in the liquid absorbent layer 313, and a compressed groove 370 extending discontinuously in a ring shape so as to surround the plurality of concave portions 360. The concave portion 360 is bottomed and located apart from each other in the longitudinal direction Y and the lateral direction X in plan view. The concave portion 360 has various known shapes such as a circle, an ellipse, a triangle, and a rectangle, in addition to the illustrated form.
The concave portions 360 can be formed by, for example, pressure and heat treatment. Specifically, in a known embossing process, the absorbent body 320 can be formed by pressing an embossing pin from the side of the top sheet 311 and compressing the absorbent body together with the top sheet 311. Thus, the thin-walled portion 361 where the concave portions 360 in the absorber 320 are located has a higher fiber density than the thick-walled portion 362 where the concave portions 360 are not located at the periphery thereof. Since the core covering sheet 322 has a plurality of high lignin regions 352, the liquid diffusibility thereof is relatively low, and the liquid absorbent core 321 may not be able to absorb the liquid by diffusion.
In the present embodiment, by providing the plurality of concave portions 360 extending into the liquid-absorbent core 321, bodily fluids can be directly retained in the concave portions 360, and the surface area of the liquid-absorbent core 321 that indirectly contacts menstrual blood through the topsheet 311 and the core covering sheet 322 is large, so that menstrual blood can be rapidly absorbed and retained in the liquid-absorbent core 321 by the two sheets 311, 322. Further, since the thin portions 361 where the concave portions 360 are located have a higher fiber density than the thick portions 362, the body fluid accumulated in the concave portions 360 can be sucked and held downward more quickly.
Fig. 29 (b) is a sectional view similar to fig. 29 (a) showing a modification of the sanitary napkin 310 according to embodiment 2.
Referring to fig. 29 (b), the concave portion 360 of the present modification is formed by an opening penetrating the liquid absorbent layer 313 in the thickness direction Z. Since the liquid-impermeable back sheet 312 is positioned on the bottom surface of the concave portion 360, the bodily fluid accumulated in the through-opening is absorbed and held by the absorbent body 320 through the peripheral wall of the opening without leaking to the outside.
< embodiment 3 of invention 3 >
Fig. 30 shows an example of a usage example of the absorbent article of the invention 3, in which the absorbent body 320 is applied to a disposable diaper (absorbent article) 380. The disposable diaper 380 is shown in a state in which side seams joining both side edge portions of the front waist pad 384 and the back waist pad 385 are peeled off and the disposable diaper 380 is stretched in the transverse direction and the longitudinal direction.
The disposable diaper 380 has a front waist region 381, a rear waist region 382, and a crotch region 383 located between the front waist region 381 and the rear waist region 382. The disposable diaper 380 includes a front waist pad 384 defining part of a front waist region 381 and a crotch region 383, a back waist pad 385 defining part of a back waist region 382 and a crotch region 383, and a liquid-absorbent structure 386 extending in the longitudinal direction on the skin-facing surface side of the front waist pad 384 and the back waist pad 385, and both side edge portions of the front waist pad 384 and the back waist pad 385 are joined to each other in a state of being overlapped with each other by a plurality of seam portions arranged at intervals in the longitudinal direction, thereby defining a waist opening and a pair of leg openings. The absorbent body 320 extends from the crotch region 383 to the front waist region 381 and the back waist region 382 in the absorbent assembly 386.
The diaper 380 is a so-called pants type diaper in which both side edges of the front waist region 381 and the rear waist region 382 are joined in advance, and the absorbent body 320 is composed of a liquid-absorbent core 321 and a core covering sheet 322 covering the liquid-absorbent core 321, and the core covering sheet 322 includes a peripheral region composed of the low lignin regions 351 and a plurality of high lignin regions 352 dispersed in the peripheral region, as in the sanitary napkin 310. In the absorbent body 320, when the inner surface and/or the outer surface of the diaper 380 is viewed, the light brown color of the core covering sheet 322 is seen through, so that the natural feeling product impression of using natural materials can be given, and the antibacterial property is excellent, and body fluid such as urination and loose stool can be rapidly transferred from the core covering sheet 322 to the liquid-absorbent core 321. The absorbent article of the present invention may be not only an underpants type diaper but also an open type diaper.
In each embodiment, a separate sheet which is bulky and excellent in cushioning properties may be disposed between the surface sheet 311 and the core covering sheet 322. Since the independent sheet is joined to the surface sheet 311, it can be said that the independent sheet is substantially a part of the surface sheet 311.
As long as it is not particularly described, various known materials generally used in this field can be used without limitation, in addition to the materials described in the present specification, as each constituent member constituting the absorbent articles 310 and 380. In addition, the terms "1 st" and "2 nd" used in the present specification and claims are used only for distinguishing the same elements, positions, and the like.
< invention 4 >
< embodiment 1 of the 4 th invention >
The following embodiment of invention 4 relates to the absorbent article shown in the drawings, and includes not only the indispensable structure of the invention but also optional and preferable structures. Hereinafter, an embodiment of a sanitary napkin 410 as an example of an absorbent article of the present invention will be described with reference to the drawings. The sanitary napkin 410 has a longitudinal direction Y, a transverse direction X, and a thickness direction Z.
Referring to fig. 31 to 33, the sanitary napkin 410 has a longitudinal center line P bisecting the dimension in the width direction thereof and a transverse center line Q bisecting the dimension in the longitudinal direction thereof, and includes a skin-facing surface (inner surface) 402 side and a non-skin-facing surface (outer surface) 403 side opposite thereto, a convex 1 st end edge 410a and a convex 2 nd end edge 410b, a convex 1 st side edge 410c and a convex 2 nd side edge 410d at the center portion where the transverse center line Q is located, a liquid-permeable top sheet 411 positioned on the skin-facing surface side, a liquid-impermeable back sheet 412 positioned on the non-skin-facing surface side, and a liquid-absorbent body 420 positioned between the two sheets 411, 412. The topsheet 411 and the absorbent body 420 are joined to each other by a known joining means such as a hot melt adhesive to form the liquid absorbent layer 413.
Further, although not shown, an intermediate sheet made of a relatively bulky fibrous nonwoven fabric may be disposed between the top sheet 411 and the absorbent member 420 in order to improve the flexibility of the sanitary napkin 410. In order to suppress leakage of body fluid, a leakage preventing sheet, which is preferably air-permeable and is preferably made of liquid-impermeable fibrous nonwoven fabric or plastic film, may be disposed between the absorbent body 420 and the back sheet 412.
The absorbent body 420 has a 1 st end edge 420a opposite to the 1 st end edge 410a, a 2 nd end edge 420b opposite to the 2 nd end edge 410b, and a 1 st side edge 420c and a 2 nd side edge 420d extending in the longitudinal direction between the 1 st end edge 420a and the 2 nd end edge 420 b. The front sheet 411 and the back sheet 412 protrude outward from the outer periphery of the absorbent body 420, and a pair of side sheets 414 extending in the longitudinal direction Y so as to face each other in the lateral direction are arranged on the skin-facing surface side of the front sheet 411. The pair of side pieces 414 are joined to the surface piece 411 by side joining portions (not shown). Although not shown, in the side panels 414, an elastic member extending in the longitudinal direction Y may be disposed so as to be contractible in an extended state in order to form a leakage preventing wall that rises toward the body side in a worn state. The side joining portion for fixing the side sheet 414 may be a seal line extending in the longitudinal direction Y and having design elements such as a pattern and a geometric pattern.
The sanitary napkin 410 has both end portions 416 formed by the front sheet 411, the back sheet 412 and the side sheets 414 and extending in the transverse direction X outside the longitudinal direction Y of the 1 st end edge 420a and the 2 nd end edge 420b of the absorbent body 420, and both side edge portions 417 extending in the longitudinal direction Y outside the transverse direction X of the 1 st side edge 420c and the 2 nd side edge 420d of the absorbent body 420. Flaps 418 formed by parts of both side edges 417 protruding outward in the transverse direction X are located in the central portion in the longitudinal direction Y of the sanitary napkin 410. Further, the sheets 411, 412, 414 stacked on each other are joined to each other by a peripheral seal portion 419 located along the outer peripheral edge of the sanitary napkin 410.
Referring to fig. 32, a plurality of fastening regions 430 are disposed on the back side of the sanitary napkin 410. The plurality of fastening regions 430 are used for fastening the sanitary napkin 410 to clothing such as underwear, and the plurality of fastening regions 430 are formed of an adhesive or a pressure-sensitive adhesive applied in a plurality of lines extending in the longitudinal direction Y. The fastening region 430 has a central region 431 extending in the longitudinal direction Y in a region overlapping with the absorbent body 420 and side regions 432 at the wings 418. The fixing region 430 is covered with a spacer (not shown) made of a plastic film.
The surface sheet 411 may be made of various liquid-permeable nonwoven fabrics of fibers, for example, having a weight per unit area of about 15g/m 2～45g/m2The nonwoven fabric of air-through fibers, the porous plastic film, the laminate of the above materials, and the like. The back sheet 412 can be formed of a liquid-impermeable and moisture-permeable plastic film, a liquid-impermeable fibrous nonwoven fabric, a laminate of the above materials, or the like. The side sheet 414 can be the same sheet as the surface sheet 411. However, in order to effectively prevent the side leakage of body fluid, it is preferable to use a sheet having hydrophobicity or waterproofness.
As the front sheet 411, a sheet having an uneven surface side can be used. The surface of the sheet is formed by a plurality of concave portions and a plurality of convex portions alternately arranged in the longitudinal direction Y or the transverse direction X, and as a method for forming the plurality of convex portions and concave portions, for example, a method for forming a dense portion and a bulky portion by controlling the amount of fibers, a method for forming concave portions by embossing, a method for forming concave portions into a concave-convex shape, and the like are considered. The fibers are arranged in the convex portion and the concave portion so as to be sparse one and dense the other in such a manner that the fiber densities are different from each other. The joining strength can be further improved by joining the portion where the fibers are sparsely arranged (the 1 st portion) to the high lignin region 452 of the core covering sheet 422 described later, while the liquid absorption can be further improved by joining the portion where the fibers are densely arranged (the 2 nd portion) to the low lignin region 451.
Even when menstrual blood is repeatedly excreted for a relatively short period of time, the menstrual blood can be temporarily accumulated in the concave portions, and leakage of menstrual blood from the surface of the front sheet 411 and between the front sheet 411 and the core covering sheet 422 can be suppressed. Further, it is preferable that a part of the concave portion of the surface sheet 411 is substantially (continuously or discontinuously) surrounded by a compressed portion in which compressed grooves are formed, a compressed concave portion formed by embossing, or the like. In this case, the body fluid accumulated in the dent can be prevented from leaking out in the lateral direction X and the longitudinal direction Y. In addition, in the case where the surface of the surface sheet is uneven, the core covering sheet 422 having a light brown color is visually recognized as darker than the convex portion in the surface view, and therefore, a decorative effect by the gradation of the color can be produced.
The outer peripheral seal portion 419 may be formed by bonding with an adhesive, bonding by a known welding means such as ultrasonic welding, thermal welding, laser welding, or high-frequency welding, or bonding by embossing, either alone or in combination. The sheets 411, 412, and 414 stacked in the thickness direction Z are bonded to each other with an adhesive such as a hot melt adhesive. Examples of the method for applying the hot melt adhesive include various known coating methods such as spiral coating, coater coating, curtain coater coating, and spray coating.
Referring to fig. 33 and 34, the absorbent body 420 includes a liquid-absorbent core 421 formed by mixing superabsorbent polymer particles (SAP) and cellulose fibers such as fluffed wood pulp and rayon fibers and shaped into a predetermined shape, and a liquid-permeable core cover sheet 422 covering the entire liquid-absorbent core 421 to improve shape retention and liquid diffusion properties of the absorbent body 420.
The dimension in the longitudinal direction Y of the core covering sheet 422 is larger than the dimension in the longitudinal direction Y of the liquid-absorbent core, and both side edge portions 422a and 422b thereof are positioned so as to overlap each other on the bottom surface side of the central portion in the transverse direction X of the liquid-absorbent core 421 so as to wrap the entire liquid-absorbent core 421. By stacking the both side edge portions 422a, 422b, an overlapping portion 423 is formed in the central portion of the absorbent body 420 in the transverse direction X, and the overlapping portion 423 is formed by stacking the both side edge portions 422a, 422b extending in the longitudinal direction Y.
The core covering sheet 422 has a 1 st covering portion 425 covering the skin-facing surface side of the liquid-absorbent core 421 and a 2 nd covering portion 426 covering the non-skin-facing surface side of the liquid-absorbent core 421. In the present embodiment, the core covering sheet 422 is formed of one continuous sheet, but may be formed of a 1 st core covering sheet forming the 1 st covering portion 425 and a 2 nd core covering sheet independent of the 1 st core covering sheet and forming the 2 nd covering portion 426.
The core covering sheet 422 is formed of various well-known fibrous nonwoven fabrics or tissue papers, mainly pulp fibers. The pulp fibers of the core cover sheet 422 have bleached pulp fibers that have been delignified and unbleached pulp fibers that have not been delignified. Here, the pulp fiber contains, in addition to a wood pulp fiber obtained from a coniferous tree or a broadleaf tree as a raw material, a non-wood pulp fiber obtained from cotton linter, abaca, hibiscus hemp, straw, bamboo, or banana as a raw material.
The core covering sheet 422 may have a multilayer structure including, for example, a 1 st layer (upper layer or lower layer) composed of regenerated cellulose fibers such as rayon fibers and hydrophilic fibers such as semi-synthetic cellulose fibers, and a 2 nd layer (lower layer or upper layer) composed of unbleached pulp fibers 442 that have not been subjected to delignification treatment. In this case, even when the 2 nd layer has a sea-island structure composed of the low lignin region 451 and the high lignin region 452, which will be described later, the body fluid can be sufficiently diffused in the 1 st layer, and thus, the unevenness in the diffusion of the body fluid in the entire core covering sheet 422 can be suppressed. This can suppress a decrease in the bonding property between the core cover sheet 422 and the topsheet 411 even after a plurality of times of absorption of body fluid, and can maintain a preferable liquid-absorbing property.
Since the core covering sheet 422 has unbleached pulp fibers, it has a light brown color (wood color) derived from a plant material such as wood as a whole. Since the other sheets 411, 412, and 414 than the core covering sheet have a white color as a whole by mixing a white pigment such as titanium dioxide with the constituent fibers, the core covering sheet 422 can be easily visually recognized through the other sheets 411, 412, and 414 in the front view and/or the back view of the sanitary napkin 410.
The pulp fiber is generally bleached pulp fiber obtained by subjecting a raw material chip to a raw material chip treatment step, then to a cooking step (a delignification treatment step 1) of adding a chemical to the raw material chip and boiling the chip under high temperature and high pressure to cook lignin, a screening step of removing foreign matters in the pulp, an oxygen exposure step (a delignification treatment step 2) of decomposing lignin remaining in the cooking step with oxygen, and a bleaching step of bleaching the pulp with various chemicals. The unbleached pulp fiber is obtained by passing through only the cooking step and the screening step, which are the 1 st stage of the delignification treatment among the above-described steps, and is obtained by performing the delignification treatment to a certain extent.
The content of lignin in the unbleached pulp fiber contained in the core covering sheet 422 is 0.2% to 10.0%.
The lignin content of unbleached pulp fibers was measured by the following method.
< method for measuring Lignin content >
Quantification of ADF
Reagent: an acidic detergent solution, cetyl trimethylammonium Bromide (Hexadecacyltrimethylammonium Bromide), 10g was dissolved in 500mL of 1N sulfuric acid to obtain a preparation.
Acetone (II)
Decalin as an antifoaming agent (alternative)
< measurement procedure >
A sample (300 g) was weighed, placed in a 50mL Erlenmeyer flask, and 30mL of an acidic detergent solution was added. The flask was covered with aluminum foil, and the flask was placed in boiling water to decompose the product for 60 minutes. After the decomposition, it was transferred to a glass fiber filter paper (GA-200) -laid Gu's crucible and subjected to suction filtration, and the residue was washed with hot water and acetone. After air drying, thermal drying is carried out. The ash obtained by removing ash by taking a constant amount after drying is ADF, but ash obtained by quantifying lignin cannot be used for this purpose.
Lignin quantification
Reagent: 72% sulfuric acid
< measurement procedure >
A few drops of 72% sulfuric acid were dropped into the above-described dry gouge crucible to wet the whole, and then about twice the amount of ADF was added, and the sulfuric acid was appropriately added every hour and left for 3 to 4 hours. Thereafter, the reaction mixture was subjected to suction filtration and washed with hot water until the furnace liquid showed no acidity. After air drying, heat drying was carried out and a constant amount was taken. Ashing was performed at 550 ℃ in a Gu-Shi crucible to determine ash content.
Since the core covering sheet 422 has unbleached pulp fibers, it has a light brown color derived from a plant material in a surface pattern as compared with the case of using a core covering sheet composed of only bleached pulp fibers, and can give an impression of a product which is gentle to the skin using a natural material to a wearer or a wearer aid. Further, since the core covering sheet 422 has a light brown color, the degree of redness of menstrual blood is suppressed when the menstrual blood excreted permeates the top sheet 411 and is absorbed and held by the absorber 420. This makes it possible to suppress aversion feeling caused by direct visual recognition of menstrual blood, and to alleviate mental anxiety caused by visual recognition of the redness of menstrual blood for example in wearers of menstrual discharge. Further, since the lignin component has an antibacterial action, it can inhibit the propagation of foreign bacteria after use and can be disposed of hygienically.
The core covering sheet 422 preferably has a lignin content of 2% to 10% in order to exhibit its natural appearance, suppression of the redness of menstrual blood, and a certain antibacterial effect. When the content of the lignin component in the core covering sheet 422 is less than 2%, the light brown color of the core covering sheet 422 may be so light that it cannot be visually distinguished from the other white sheets 411, 412, and 414. On the other hand, when the content of the lignin component in the core covering sheet 422 is greater than 10%, the chroma of the lignin component is deep, and the natural appearance of the natural material may be impaired, and the redness of menstrual blood may be difficult to visually recognize, and the menstrual blood amount may not be accurately grasped.
Referring to fig. 33 and 34, the liquid absorbent layer 413 has a 1 st end region 413A and a 2 nd end region 413B opposite to each other in the longitudinal direction Y, and a middle region 413C between the 1 st end region 413A and the 2 nd end region 413B. The liquid absorbent layer 413 further includes a plurality of concave portions 460 recessed from the front sheet 411 toward the back sheet 412, and a compressed groove 470 extending discontinuously in a ring shape so as to surround the plurality of concave portions 460.
The compressed strip groove 470 has a 1 st contour strip groove 471 of a curved shape located in the 1 st end region 413A, a 2 nd contour strip groove 472 of a curved shape located in the 2 nd end region 413B, a 3 rd contour strip groove 473 located between the 1 st contour strip groove 471 and the 2 nd contour strip groove 472 and being the intermediate region 413C, a 1 st inner contour strip groove 474 located in the 1 st contour strip groove 471, and a 2 nd inner contour strip groove 475 located in the 2 nd contour strip groove 472.
The concave portion 460 has a bottom, extends continuously from the topsheet 411 to a part of the liquid-absorbent core 421, and is located at a position spaced apart from each other in the longitudinal direction Y and the lateral direction X in a plan view. The concave portion 460 includes a 1 st concave portion 460a located in a region surrounded by the 1 st inner groove 474, the 2 nd inner groove 475, and the 3 rd outer groove 473, a 2 nd concave portion 460b disposed in a region surrounded by the 1 st outer groove 471 and the 1 st inner groove 474, and a 3 rd concave portion 460c disposed in a region surrounded by the 2 nd outer groove 472 and the 2 nd inner groove 475.
The 1 st concave portion 460a is substantially circular, whereas the 2 nd concave portion 460b and the 3 rd concave portion 460c have a substantially cross shape, unlike the 1 st concave portion 460 a. The 1 st concave portion 460a is arranged more densely than the 2 nd concave portion 460b and the 3 rd concave portion 460 c. The concave portion 460 may have various known shapes such as a circle, an ellipse, a triangle, and a rectangle, in addition to the illustrated form. For example, when the 1 st concave portion 460a has a substantially circular shape, the diameter is 1.0mm to 1.5mm, the pitch in the transverse direction X is 3.0mm to 5.0mm, and the pitch in the longitudinal direction Y is 5.0mm to 7.0 mm. Here, the pitch means a separation dimension between center points of the 1 st concave portions 460 a.
By forming the plurality of concave portions 460 in the liquid absorbent layer 413, kinks and deformation of the absorbent body 420 during wearing can be suppressed. In particular, since the region where the 1 st concave portion 460a is arranged is a portion of the absorbent body 420 which is thicker than other regions and faces the excretory opening of the wearer, the 1 st concave portion 460a can be arranged to improve rigidity, and thus, a kink or deformation during wearing can be effectively prevented. Further, by forming the compressed groove 470 extending annularly in the longitudinal direction Y over the entire area of the absorbent body 420, the bodily fluid can be rapidly diffused by the compressed groove 470, and the absorbent body 420 can be deformed into a curved shape along the entire shape of the body.
The concave portion 460 of the liquid absorbent layer 413 can be formed by, for example, pressure and heat treatment. Specifically, in a known embossing process, the absorbent member 420 can be formed by pressing a heated embossing pin from the surface sheet 411 side of the liquid absorbent layer 413 and compressing the absorbent member 411 together.
In general, the core-covering sheet has a function of retaining the shape of the liquid-absorbent core and a function of absorbing and diffusing body fluid having passed through the surface sheet and transferring the body fluid to the liquid-absorbent core, and therefore, a hydrophilic sheet is preferably used, but since the content of the lignin component in the unbleached pulp fiber contained in the core-covering sheet 422 of the present embodiment is high, the degree of hydrophilicity is low, the core-covering sheet is hydrophobic, menstrual blood having passed through the surface sheet 411 cannot be sufficiently absorbed and retained, and menstrual blood cannot be rapidly transferred to the liquid-absorbent core 421.
In the present embodiment, by having the plurality of concave portions 460 extending into the liquid-absorbent core 421, menstrual blood can be directly retained in the concave portions 460, and the surface area of the liquid-absorbent core 421 indirectly contacting with menstrual blood through the topsheet 411 and the core covering sheet 422 is large, so that menstrual blood can be rapidly absorbed and retained in the liquid-absorbent core 421 by the two sheets 411, 422.
Since the core covering sheet 422 has the unbleached pulp fibers, the diffusion property is lower than that of a core covering sheet formed of a normal tissue paper, and menstrual blood entering the concave portions 460 is not diffused but held at the bottom and the peripheral wall of the concave portions 460, and thus, body fluid can be absorbed in a dot shape at the arrangement portions of the plurality of concave portions 460. Therefore, the body fluid can be prevented from diffusing to both side edges of the liquid-absorbent core 421, and the menstrual blood can be prevented from adhering to the body through the side sheets 414.
In addition, in the joint interface formed by the hot melt adhesive between the surface sheet 411 and the core covering sheet 422, the bleached pulp fibers may absorb menstrual blood and swell, and the joint portions may peel off, resulting in a decrease in joint strength. Since the unbleached pulp fiber is less hydrophilic and hydrophobic than the bleached pulp fiber 441, it does not easily absorb menstrual blood and swells, and the joint portion does not peel. Therefore, the core covering sheet 422 can suppress peeling and floating of the surface sheet 411 during wearing by mixing the bleached pulp fibers and the unbleached pulp fibers. In addition, when the amount of the adhesive is increased in order to increase the joining strength of the two sheets 411 and 422, the sheet rigidity may be increased and the flexibility and liquid permeability may be decreased, but the joining strength can be controlled by adjusting the content of the unbleached pulp fibers so as not to cause the above-described disadvantages.
The 2 nd covering portion 426 of the core covering sheet 422 is joined to the back sheet 412 by a hot melt adhesive. Since the core covering sheet 422 contains unbleached pulp fibers, the back sheet 412 and the core covering sheet 422 are less likely to peel at the joining interface where they are joined by a hot melt adhesive, and have a required joining strength, as compared with a core covering sheet formed of only bleached pulp fibers. Therefore, it is not necessary to increase the weight per unit area of the hot-melt adhesive in order to prevent the sheet from peeling off, and the sheet stiffness is increased by increasing the weight per unit area of the hot-melt adhesive, and the conformability to the absorber 420 is not lowered.
Preferably, the 1 st covering portion 425 and the front sheet 411, and the 2 nd covering portion 426 and the back sheet 412 of the core covering sheet 422 are bonded to each other with a rubber-based adhesive, for example, an SIS-based hot melt adhesive. By bonding the sheets 411, 412, and 422 to each other with an SIS adhesive, the Volatile Organic Compound (VOC) value can be reduced compared to an EVA resin adhesive or the like using an organic solvent, and the sheets can be used more gently and safely on the skin.
The thin-walled portions (bottoms of the concave portions 460) 461 where the concave portions 460 are located in the absorber 420 have a higher density than the thick-walled portions 462 located at the periphery thereof where the concave portions 460 are not present. Since the thin portions 461 at which the concave portions 460 are located have a high density, menstrual blood entering the concave portions 460 is absorbed and diffused more rapidly by the thin portions 461.
The core covering sheet 422 preferably has a formation index of 50 to 300. When the formation index of the core covering sheet 422 is less than 50, the pulp fibers are uniformly arranged at a high density, and the liquid permeability is lowered, and menstrual blood cannot be rapidly transferred to the liquid-absorbent core 421. On the other hand, if the formation index is more than 300, a portion having an extremely poor texture is formed, and the tensile strength is lowered, and there is a possibility that the portion is locally broken during use.
< method for measuring formation index >
The core cover sheet 422 was measured for formation index using a formation tester FMT-MIII manufactured by nomuram co. The formation index of both surfaces of 3 samples was measured under the conditions that the measurement area was 250mm × 180mm and the measurement time was 3 seconds/sample, and the average value thereof was taken as a measurement value. The uniformity index means that the smaller the measured value, the less the texture unevenness.
Since unbleached pulp fibers have higher rigidity than bleached pulp fibers, when the core cover sheet 422 is formed only of unbleached pulp fibers, the softness is relatively low, and the core cover sheet cannot follow the movement of the surface sheet 411, and the core cover sheet may be peeled off from the surface sheet 411. Thus, the core covering sheet 422 has desired softness, and specifically, the core covering sheet 422 has a crinkling ratio of 7% to 20%. When the wrinkle ratio of the core covering sheet 422 is less than 7%, the rigidity of the core covering sheet 422 is relatively high and cannot follow the movement of the surface sheet 411, while when the wrinkle ratio is more than 20%, the core covering sheet 422 is too soft and may be broken during the manufacturing process or during the use.
< measurement method of wrinkling Rate >
The percent wrinkling of the core cover sheet 422 was measured using the underwater elongation method. The core covering sheet 422 was cut to 100mm × 100mm to prepare a measurement sample, the measurement sample was immersed in water for 10 seconds and then lifted, and the wrinkling rate was calculated from the amount of change in dimension by the following equation. 3 measurements (n-3) were made, and the average value was taken as the measurement value.
Wrinkling rate (%) { (dimension after immersion in water)/(dimension before immersion in water) -1 } × 100
The surface sheet 411 can use a hydrophilic sheet containing cotton fibers (including organic cotton). When this sheet is used as the top sheet 411, the cushioning properties, skin-contactability, and liquid-absorbing properties are excellent. Further, by forming the liquid absorbent layer by the surface sheet 411 containing cotton fibers and the core covering sheet 422 having the high lignin regions 452, the liquid retention of the fibers is relatively small in the core covering sheet 422, and the surface sheet has high moisture absorbency, so that moisture in the absorbent body 420 can be absorbed in the surface sheet 411. This can suppress the generation of moisture between the sanitary napkin and the body, and suppress the internal stuffiness.
Preferably, the klemm water absorption of the core covering sheet 422 is higher than that of the surface sheet 411 containing cotton fibers. By making the klemm water absorption rate of the core covering sheet 422 higher than the klemm water absorption rate of the topsheet 411 positioned on the skin-facing surface side of the core covering sheet 422, menstrual blood absorbed and diffused in the topsheet 411 can be absorbed by the core covering sheet 422 to be absorbed and rapidly transferred to the liquid-absorbent core 421, and liquid remaining on the topsheet 411 can be effectively suppressed.
< method for measuring Klelm Water absorption >
The gram water absorption of the core covering sheet 422 was measured in accordance with the gram water absorption test (JIS-L1907, P8141). As the measuring instrument, a ruler, a stopwatch, a plastic container, and artificial urine (colored blue No. 1) were used. A sheet obtained by cutting the core covering sheet 422 into a size of 25mm in width and 150mm in length was used as a sample (N ═ 3). First, artificial urine is put into a plastic container until the depth of the artificial urine reaches 10mm or more. Subsequently, the extracted test piece was fixed by a fixing chuck and set to be immersed in artificial urine at a depth of 5mm from the sample tip. The test piece was left in this state for 120 seconds (environment: temperature 20 ℃ C./humidity 60%). The artificial urine rises along the specimen, and the suck-up distance on the specimen is measured from the surface of the artificial urine. A longer pick-up distance indicates a higher klemm water absorption.
In this case, the layer (upper layer) on the skin-facing surface side is preferably substantially formed of cotton fibers. In this case, the cotton fiber can absorb moisture more effectively at a portion near the skin.
The top sheet 411 may have a multilayer structure, and a layer (upper layer) on the skin-facing surface side may be formed mainly of cotton fibers, and a layer (lower layer) on the non-skin-facing surface side may be formed mainly of hydrophobic synthetic resin fibers. In this case, the klemm water absorption rate of the surface sheet 411 is lower than that of the core covering sheet 422 regardless of whether the surface sheet 411 contains water-absorbent cotton fibers on the skin side. By making the klemm water absorption rate of the top sheet 411 lower than the klemm water absorption rate of the core covering sheet 422, the body fluid can be diffused in the core covering sheet 422 closer to the absorbent body 420 than the surface of the sanitary napkin 410 without being diffused in the body fluid, and the body fluid absorbed in the absorbent body 420 can be suppressed from flowing back (getting damp) to the surface side.
As described above, the liquid-absorbent core 421 may alternatively include cellulose fibers such as cotton and pulp fibers, cellulose fibers including semi-synthetic cellulose fibers such as acetate fibers, and regenerated cellulose fibers such as rayon. Since the core covering sheet 422 also has cellulose fibers made of bleached pulp fibers and unbleached pulp fibers, as in the liquid-absorbent core 421, the affinity thereof is high, and the bonding strength is increased when the core covering sheet 422 and the liquid-absorbent core 421 are welded to each other in the compressed groove 470.
Further, the liquid-absorbent core 421 may be formed of only the SAP particles. In this case, the absorbent body 420 includes a liquid-absorbent core 421 composed of only SAP particles and a core covering sheet 422 covering the liquid-absorbent core 421. In this case, the liquid retention is relatively low by providing the core covering sheet 422 with the low lignin regions 451 described later, while the liquid-absorbent core 421 is formed only of SAP particles having a high liquid-absorbing capacity, so that the entire absorbent body 420 can exhibit appropriate liquid-absorbing properties.
The liquid-absorbent core 421 may have a plurality of functional particles formed of activated carbon, zeolite, or the like and having a function of adsorbing odor of body fluid such as menstrual blood. By providing the liquid-absorbent core 421 with odor-absorptive properties, the sanitary napkin 410 can be used and discarded in a more sanitary and clean manner in addition to the antibacterial properties of the core covering sheet 422.
Referring again to fig. 33 and 34, an overlapping portion 423 in which both side edge portions 422a, 422b of the core covering sheet 422 are laminated on each other is located at a central portion in the transverse direction X of the absorbent body 420. Since the overlapping portion 423 is a portion where the core covering sheet 422 is stacked, the light brown color of the unbleached pulp fibers is visually recognized as darker than other portions of the absorbent body 420, and becomes an important point in design as a line extending in the longitudinal direction Y in an appearance view. The line extending in the longitudinal direction Y may be used as a mark indicating the central portion of the absorbent body 420 for positioning when the sanitary napkin 410 is attached to underwear or the like. Even when the liquid-absorbent core 421 absorbs a large amount of menstrual blood and the menstrual blood oozes out from both edges thereof, the leakage of menstrual blood to the outside from both edges 420a and 420b of the absorbent body 420 can be effectively suppressed because the overlapping portions 423 containing relatively many hydrophobic unbleached pulp fibers are located outside in the longitudinal direction Y of both edges of the liquid-absorbent core 421.
Fig. 35 is a cross-sectional view similar to fig. 34 of an example of a modification of the absorber 420. In the present modification, the plurality of concave portions 460 formed in the liquid absorbent layer 413 are formed by openings that penetrate the topsheet 411 and the absorbent body 420. The opening can be formed by hollowing out the entire thickness of the absorbent layer 413. Since the liquid-impermeable back sheet 412 is positioned on the bottom surface of the concave portion 460, the body fluid accumulated on the bottom surface is absorbed and held by the absorber 420 through the peripheral wall of the opening without leaking to the outside.
< embodiment 2 of the 4 th invention >
Fig. 36 is a plan view of an absorber 420 of a sanitary napkin 410 according to embodiment 2 of the present invention 4, fig. 37 is a partially enlarged view of a region surrounded by a XXXVII line in fig. 36, and fig. 38 is a sectional view of the sanitary napkin according to embodiment 2, which is the same as that in fig. 34.
In the present embodiment, the 1 st coating portion 425 of the core covering sheet 422 has a low lignin region (lignin low content region) 451 having a relatively low content of lignin component and a high lignin region (lignin high content region) 452 having a relatively high content of lignin component compared to the low lignin region 451. The low-lignin regions 451 are formed primarily by the aggregation of bleached pulp fibers 441 and the high-lignin regions 452 are formed primarily by the aggregation of unbleached pulp fibers 442. In a plan view of the 1 st coat section 425 of the core covering sheet 422, the low lignin regions 451 are peripheral regions located in a relatively large range on the outer surface of the core covering sheet 422, and the high lignin regions 452 are disposed so as to be scattered in the low lignin regions 451. Further, since the arrangement is such that the 1 st covering section 425 of the core covering sheet 422 has a sea-island structure in which the low lignin region 451 is a sea and the high lignin region 452 is an island.
The core cover sheet 422 of the present embodiment is formed by interlacing a mixture of bleached pulp fibers 441 and unbleached pulp fibers 442 in a paper making process thereof into a sheet shape, and since the bleached pulp fibers 441 are mainly disposed in the low-lignin region 451 and the unbleached pulp fibers 442 are mainly disposed in the high-lignin region 452, the boundary between the two regions 451, 452 is not clear, and cannot be clearly distinguished. Further, as a method for forming the high lignin regions 452 dispersedly in the low lignin regions 451 over the entire outer surface of the core covering sheet 422, for example, a mixing method of the pulp fibers 441 and 442, a mixing ratio, a conveying speed of a conveyor at the time of manufacturing, a nozzle diameter at the time of depositing the pulp fibers 440 on the conveyor by air ejected from a plurality of nozzles, an air volume of the blown air, an air velocity, and the like may be appropriately adjusted.
Since the two zones 451, 452 are formed by adjusting various conditions of the production process, it can be said that the unbleached pulp fiber 442 is contained in part of the low lignin zone 451, and the bleached pulp fiber 441 is contained in the high lignin zone 452. Therefore, the low-lignin region 451 and the high-lignin region 452 are not formed of only the bleached pulp fiber 441 and the unbleached pulp fiber 442, respectively, and may contain other fibers than the pulp fiber, for example, the content of the bleached pulp fiber 441 in the pulp fiber of the low-lignin region 451 is 50% to 100%, and the content of the unbleached pulp fiber 442 in the pulp fiber of the high-lignin region 452 is 50% to 100%.
The high lignin region 452 is a region in which the content of the lignin component is higher than that of the low lignin region 451 which is a peripheral region of the core covering sheet 422, and therefore the high lignin region 452 can be formed without using the bleached pulp fiber 441 and the unbleached pulp fiber 442. For example, the high lignin region 452 having a higher lignin content than the surrounding region can be formed by allowing a liquid containing a lignin component to dispersedly infiltrate into a fibrous nonwoven fabric sheet composed of rayon fibers or synthetic fibers.
Referring to fig. 38, since the 1 st cladding portion 425 of the core covering sheet 422 has the low lignin region 451 and the plurality of high lignin regions 452 scattered around the low lignin region 451, the two regions 451, 452 alternately appear in the transverse direction X in the cross-sectional view. Since the high lignin regions 452 are arranged so as to be scattered in the low lignin region 451, it can be said that the low lignin regions 451 and the high lignin regions 452 are alternately arranged not only in the transverse direction X but also in the longitudinal direction Y.
By thus positioning the low lignin regions 451 and the high lignin regions 452 at alternating positions in the transverse direction X and the longitudinal direction Y in the cross-sectional view of the 1 st coating section 425, menstrual blood that has passed through the top sheet 411 in the hydrophilic low lignin regions 451 can be absorbed and held by the liquid-absorbent core 421 by being absorbed in a rapid manner, and a desired absorption rate can be achieved.
Since the low-lignin region 451 and the high-lignin region 452 are formed of the bleached pulp fibers 441 and the unbleached pulp fibers 442, the shape of the boundary between them is not clear, and they have at least a meandering wave shape in a plan view, not a straight line shape. Thus, a required absorption area per unit width (for example, 1.0mm) near the boundary between the low lignin region 451 and the high lignin region 452 can be maintained.
< embodiment 3 of the 4 th invention >
Fig. 39 is a plan view of the absorbent article according to embodiment 3 of the 4 th aspect of the present invention, and the absorbent body 420 is applied to a disposable diaper (absorbent article) 480. The disposable diaper 480 is shown in a state where side seams joining both side edge portions of the front waist pad 484 and the back waist pad 485 are peeled off and the disposable diaper 480 is stretched in the transverse direction and the longitudinal direction.
The disposable diaper 480 has a front waist region 481, a rear waist region 482, and a crotch region 483 located between the front waist region 481 and the rear waist region 482. The diaper 480 includes a front waist pad 484 partitioning a front waist region 481 and a crotch region 483, a rear waist pad 485 partitioning a rear waist region 482 and a crotch region 483, and an absorbent structure 486 extending in the longitudinal direction on the skin-facing surface side of the front waist pad 484 and the rear waist pad 485, and both side edge portions of the front waist pad 484 and the rear waist pad 485 are joined to each other in a state of being overlapped with each other by a plurality of seam portions arranged at intervals in the longitudinal direction, thereby partitioning and forming a waist opening and a pair of leg openings. The absorbent body 420 extends from the crotch region 483 to the front waist region 481 and the rear waist region 482 in the liquid-absorbent structure 486.
The diaper 480 is a so-called pants type diaper in which both side edges of the front waist region 481 and the rear waist region 482 are joined in advance, and similarly to the sanitary napkin 410, the absorbent body 420 is composed of a liquid-absorbent core 421 and a core covering sheet 422 covering the liquid-absorbent core 421, the core covering sheet 422 contains the unbleached pulp fibers 442, and a plurality of concave portions 460 are formed in the liquid-absorbent layer 413. In the absorbent body 420, when the inner surface and/or the outer surface of the diaper 480 is observed, the light brown color of the core covering sheet 422 is seen through, whereby a natural feeling product impression using natural materials can be given, and excellent antibacterial properties can be provided, and body fluids such as urination and loose stool can be rapidly transferred from the core covering sheet 422 to the liquid-absorbent core 421 via the plurality of concave portions 460. The absorbent article of the present invention may be not only a pants-type diaper but also an open-type diaper.
In each embodiment, a separate sheet having bulkiness and excellent cushioning properties may be disposed between the surface sheet 411 and the core covering sheet 422. Since the separate sheet is joined to the surface sheet 411, it can be said that the separate sheet is a part of the surface sheet 411.
Unless otherwise specified, various known materials generally used in the field can be used for each of the components constituting the absorbent articles 410 and 480, in addition to the materials described in the present specification, without limitation. In addition, the terms "1 st" and "2 nd" used in the specification and the claims are used only for distinguishing the same elements, positions, and the like.

Claims (12)

1. An absorbent article comprising a liquid-permeable top sheet positioned on a skin-facing surface side, a liquid-impermeable back sheet positioned on a non-skin-facing surface side, and an absorbent body positioned between the top sheet and the back sheet,
the absorbent body comprises a liquid-absorbent core and a core-covering sheet covering the liquid-absorbent core,
the core-covering sheet has a 1 st core-covering sheet which is located on the skin-facing surface side of the liquid-absorbent core and contains 1 st pulp fibers and a 2 nd core-covering sheet which is located on the non-skin-facing surface side of the liquid-absorbent core and contains 2 nd pulp fibers,
the 1 st pulp fiber is unbleached pulp fiber, the 2 nd pulp fiber is bleached pulp fiber,
the 1 st core covering sheet contains the 1 st pulp fiber in a larger amount than other constituent fibers, the 2 nd core covering sheet contains the 2 nd pulp fiber in a larger amount than other constituent fibers,
the kappa number of the pulp fiber forming the 2 nd core covering sheet is less than 5.8,
the kappa number of the 2 nd pulp fiber is smaller than that of the 1 st pulp fiber.
2. The absorbent article of claim 1, wherein,
the kappa number of the 1 st pulp fiber is 8-40,
The difference between the kappa number of the No. 2 pulp fiber and the kappa number of the No. 1 pulp fiber is more than 2.4.
3. The absorbent article of claim 2, wherein,
the difference between the kappa number of the 2 nd pulp fiber and the kappa number of the 1 st pulp fiber is more than 7.2.
4. The absorbent article according to claim 1 or 2, wherein,
the 1 st core covering sheet has both side edge portions between the non-skin-facing surface of the liquid-absorbent core and the 2 nd core covering sheet.
5. The absorbent article of claim 4,
the absorbent article has a transverse direction and a longitudinal direction,
the sum of the lateral dimensions of the side edge portions is smaller than 1/3 of the lateral dimension of the liquid-absorbent core.
6. The absorbent article according to claim 5,
the 1 st core covering sheet is superposed on the lateral outer sides of both side edges of the liquid-absorbent core in the thickness direction.
7. The absorbent article according to claim 1 or 2, wherein,
the absorbent article has a transverse direction and a longitudinal direction,
both side edges of the 1 st core covering sheet and both side edges of the 2 nd core covering sheet extend outward in the lateral direction from both side edges of the liquid-absorbent core,
The 1 st core covering sheet and the 2 nd core covering sheet are joined to each other outside the lateral direction of both side edges of the liquid-absorbent core.
8. The absorbent article of claim 7,
the longitudinal length dimension of the joint portion between the 1 st core covering sheet and the 2 nd core covering sheet is 50mm or less.
9. The absorbent article according to claim 1 or 2, wherein,
an indicator for indicating the presence or absence of excrement visible from outside the back sheet is located on the non-skin-facing surface side of the liquid-absorbent core,
the indicator portion and the 2 nd core covering sheet overlap in a thickness direction.
10. The absorbent article according to claim 1 or 2, wherein,
an independent member is located between the surface sheet and the 1 st core covering sheet.
11. The absorbent article according to claim 5,
the surface sheet has convex portions and concave portions respectively extending in the longitudinal direction and alternately arranged in the lateral direction,
the concave portions are in contact with the absorber and the convex portions are separated from the absorber.
12. The absorbent article according to claim 5,
the liquid-absorbent core has a narrow width region of the liquid-absorbent core having a smaller dimension in the lateral direction at the center in the longitudinal direction thereof,
The back sheet has a colored portion at a portion overlapping the narrow width region.
CN202210275862.XA 2018-06-29 2019-06-28 Absorbent article Active CN114748248B (en)

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JP2018125325A JP6838013B2 (en) 2018-06-29 2018-06-29 Absorbent article
JP2018125326A JP6839135B2 (en) 2018-06-29 2018-06-29 Absorbent article
JP2018-125327 2018-06-29
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JP2018-125325 2018-06-29
CN201980043799.3A CN112334111B (en) 2018-06-29 2019-06-28 Absorbent article
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