CN111748910A - Air-permeable nonwoven fabric, method for producing same, and absorbent article - Google Patents

Air-permeable nonwoven fabric, method for producing same, and absorbent article Download PDF

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Publication number
CN111748910A
CN111748910A CN202010212881.9A CN202010212881A CN111748910A CN 111748910 A CN111748910 A CN 111748910A CN 202010212881 A CN202010212881 A CN 202010212881A CN 111748910 A CN111748910 A CN 111748910A
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CN
China
Prior art keywords
nonwoven fabric
fiber
fibers
under load
per unit
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.)
Pending
Application number
CN202010212881.9A
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Chinese (zh)
Inventor
青野正志
松田康志
小岛卓
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.)
JNC Corp
JNC Fibers Corp
Original Assignee
JNC Corp
JNC Fibers Corp
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Publication of CN111748910A publication Critical patent/CN111748910A/en
Pending legal-status Critical Current

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Classifications

    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/42—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties characterised by the use of certain kinds of fibres insofar as this use has no preponderant influence on the consolidation of the fleece
    • D04H1/4382—Stretched reticular film fibres; Composite fibres; Mixed fibres; Ultrafine fibres; Fibres for artificial leather
    • 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
    • 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
    • A61F13/45—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 shape
    • A61F13/47—Sanitary towels, incontinence pads or napkins
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/44—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties the fleeces or layers being consolidated by mechanical means, e.g. by rolling
    • 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
    • A61F13/15203—Properties of the article, e.g. stiffness or absorbency
    • A61F2013/15284—Properties of the article, e.g. stiffness or absorbency characterized by quantifiable properties
    • A61F2013/15463—Absorbency

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  • Health & Medical Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Epidemiology (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Heart & Thoracic Surgery (AREA)
  • Vascular Medicine (AREA)
  • Biomedical Technology (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Textile Engineering (AREA)
  • Mechanical Engineering (AREA)
  • Nonwoven Fabrics (AREA)
  • Absorbent Articles And Supports Therefor (AREA)

Abstract

The present invention provides a breathable nonwoven fabric, a method for producing the same, and an absorbent article, wherein liquid return is suppressed by suppressing the weight per unit area of the nonwoven fabric to be low and maintaining the form thereof under a high load. A gas-permeable nonwoven fabric containing 50gf/cm2Thickness under load to 3.5gf/cm2The ratio of the thickness under load is 0.5 to 0.8, and 50gf/cm2The surface area of the fiber per unit volume under load was 70cm2/cm3～120cm2/cm3。

Description

Air-permeable nonwoven fabric, method for producing same, and absorbent article
Technical Field
The present invention relates to a nonwoven fabric used as a member of an absorbent article and an absorbent article using the same.
Background
Absorbent articles such as disposable diapers have been widely used from the past, and include a top sheet (top sheet) that directly contacts the skin and permeates excretory fluid such as urine, an absorbent body that holds the excretory fluid on the back side thereof, and a second sheet (second sheet) that spreads the excretory fluid over the entire absorbent body. In an absorbent article, although the excretory fluid is held by the absorbent body, the excretory fluid may flow back toward the skin side when a load is applied. The phenomenon in which the excretory fluid flows back from the absorbent body to the skin side is called fluid returning, which is a factor causing discomfort due to wetness or skin inflammation due to moisture. Therefore, in the absorbent article, it is required not to return the excretory fluid held by the absorbent body to the skin side, and a second sheet structure that meets the above requirements has been studied.
The second sheet of the absorbent article mainly contains a breathable (through-air) nonwoven fabric. The air-permeable nonwoven fabric is a nonwoven fabric classified as a thermal bond (thermal bond) nonwoven fabric, sometimes also referred to as an air through (air) nonwoven fabric, and is obtained, for example, by heat-treating a web (web) containing composite fibers of at least two thermoplastic resins having different melting points. As a method of heat-treating a web, for example, a method of thermally bonding fibers to each other by a heat treatment apparatus (for example, a hot-air through-type heat treatment apparatus or a hot-air blowing-type heat treatment apparatus) including a transport support for supporting and transporting a web to form a nonwoven fabric is known.
As for the second sheet material, for example, patent document 1 has proposed an absorbent article including a second sheet material having a predetermined compression hardness, which has an effect of improving the absorption rate of the diaper surface, preventing the back-flow of body fluid, preventing the wet-out and staining of the diaper surface, and making the diaper surface portion flexible. The second sheet disclosed in patent document 1 is obtained by thermally bonding a thermally bondable conjugate fiber having a fineness in a specific range by a hot air penetration heat treatment machine and then performing a pressing treatment.Further, 0.5gf/cm is disclosed2The thickness of the second sheet under load is 0.7mm to 0.9 mm. The second sheet of patent document 1 has high density and high flexibility.
Further, a nonwoven fabric has been proposed which suppresses liquid return by securing a thickness when a load is applied. For example, patent document 2 discloses a second sheet having a basis weight of 30g/m2Above, 50gf/cm2An air-through or air-laid (air-laid) nonwoven fabric having a thickness of 0.35mm to 1mm under load. The invention of patent document 2 has an object to provide a disposable diaper in which liquid return is less likely to occur even when a large amount of urine is absorbed, and in view of the object, even when a high load (50 gf/cm) is assumed in which a load applied by the weight of a wearer is applied while the diaper is worn2) In addition, it is considered that the thickness can be maintained as desired, and thus the excellent effect of reducing the amount of liquid returning can be exhibited.
Further, for example, patent document 3 proposes a second sheet material comprising a polyester fiber having a single fiber fineness of 2dtex (dtex) to 8dtex, which is obtained by hydrophilizing the fiber surface, and having a weight per unit area of 40g/m2～60g/m2The spunlace nonwoven fabric of (1) and is formed of a non-adhesive agent.
[ Prior art documents ]
[ patent document ]
[ patent document 1] Japanese patent laid-open No. 2005-52186
[ patent document 2] Japanese patent laid-open No. 2007-159943
[ patent document 3] Japanese patent laid-open No. 2017-148284
Disclosure of Invention
[ problems to be solved by the invention ]
The second sheet of patent document 1 is a high-density and flexible sheet for preventing liquid-returning and for obtaining effects such as high flexibility of the surface portion of the diaper. However, the softness reduces the thickness under load, and the liquid-returning preventive property may not be sufficiently exhibited. Further, the second sheet of patent document 2 describes that the sheet is made under a low load (49Pa is 0.5 gf/cm) in order to secure the thickness under load2) The thickness of (A) is about 1.4mm to 1.9mm, and the nonwoven fabric is thick under a low load. Further, the nonwoven fabric of patent document 3 is disclosed to be excellent in softness because it is a spunlace nonwoven fabric, but on the other hand, it is weak in compression resistance and it is necessary to increase the weight per unit area in order to secure the liquid-returning prevention property, and specifically, it is preferable to set the weight per unit area to 40g/m2～60g/m2。
In view of such circumstances, the present invention provides a nonwoven fabric in which liquid return is suppressed by keeping the weight per unit area of the nonwoven fabric low and also maintaining a constant thickness even under a high load.
[ means for solving problems ]
The inventors have made extensive studies to solve the above problems, and as a result, have found that a nonwoven fabric is thin at low load and can maintain a constant thickness even at high load. When the easiness of crushing the nonwoven fabric was grasped, attention was paid to the case of low load (3.5 gf/cm)2Under load) and at high load (50 gf/cm)2Under load) and obtained the knowledge that the ratio of the thickness thereof and 50gf/cm were controlled2The surface area of the fibers per unit volume under load can be reduced to reduce the liquid return and obtain a nonwoven fabric having a low weight per unit area and a low liquid return, thereby completing the present invention.
The present invention includes the following constitutions.
[1]A gas-permeable nonwoven fabric containing 50gf/cm2Thickness under load to 3.5gf/cm2The ratio of the thickness under load is 0.5 to 0.8, and 50gf/cm2The surface area of the fiber per unit volume under load was 70cm2/cm3～120cm2/cm3。
[2]According to [1]The breathable non-woven fabric has a weight per unit area of 20g/m2～35g/m2。
[3] The air-permeable nonwoven fabric according to [1] or [2], which comprises a conjugate fiber comprising polyethylene terephthalate and polyethylene, and being any one selected from the group consisting of a side-by-side conjugate fiber, an eccentric sheath-core conjugate fiber, and a concentric sheath-core conjugate fiber.
[4] A method for producing a breathable nonwoven fabric according to any one of [1] to [3], comprising: a step of making a web of composite fibers, the composite fibers including polyethylene terephthalate and polyethylene and being any one selected from the group consisting of side-by-side composite fibers, eccentric sheath-core composite fibers, and concentric sheath-core composite fibers; a step of heat-treating the web obtained in the step by a ventilation method; and a step of compacting the web immediately after the heat treatment step.
[5] An absorbent article comprising the air-permeable nonwoven fabric according to any one of [1] to [3 ].
[ Effect of the invention ]
By mixing 3.5gf/cm2Thickness under load and 50gf/cm2The ratio of the thickness under load is set to 0.5 to 0.8, the shape of the nonwoven fabric is maintained, and the return of excretory fluid temporarily absorbed by the absorbent body to the skin side is suppressed. Further, the surface area of the fiber per unit volume was set to 70cm2/cm3～120cm2/cm3The liquid diffusion due to the capillary phenomenon can be suppressed, and the liquid return can be reduced. As described above, according to the present invention having the above configuration, the present invention has sufficient absorption of the excreted liquid, and suppresses liquid return even under load.
Detailed Description
The nonwoven fabric of the present invention is 50gf/cm2Thickness under load to 3.5gf/cm2The ratio of the thickness under load is 0.5 to 0.8, and 50gf/cm2The surface area of the fiber per unit volume under load was 70cm2/cm3～120cm2/cm3The air-permeable nonwoven fabric of (4) is suitable for use as a second sheet of an absorbent article.
The nonwoven fabric of the present invention is a breathable nonwoven fabric, and as a raw material thereof, a thermal adhesive fiber-containing article in which fibers are bonded to each other by heat can be used. For example, the thermal adhesive conjugate fiber may be used singly or in combination of two or more types (a mixed fiber). Preferably, the composite fiber is a composite fiber having thermal adhesiveness formed by compounding a plurality of resins having different melting points. The thermal adhesive component of the conjugate fiber may be a thermoplastic resin component that forms a bond by heat fusion by passing hot air through the web including the fibers. The thermal bonding points between the fibers are formed by melting a thermoplastic resin component having a low melting point by hot air treatment. Examples of the resin component constituting the heat-bondable fiber include: polyolefin-based (for example, polypropylene, propylene copolymer [ copolymer of propylene as a main component and other α -olefin; for example, ethylene-propylene binary copolymer, propylene-butene-1 binary copolymer, propylene-hexene-1 binary copolymer, etc. ], polyethylene, etc.), polyester-based (for example, polyethylene terephthalate), and polyamide-based (for example, nylon 6, etc.). Specific combinations of the low-melting-point component and the high-melting-point component of the conjugate fiber include polyethylene (low-melting-point component) and polypropylene (high-melting-point component), polyethylene (low-melting-point component) and polyethylene terephthalate (high-melting-point component), and the like, and particularly, conjugate fibers containing polyethylene (low-melting-point component) and polyethylene terephthalate (high-melting-point component) are preferable in terms of bulkiness and nonwoven fabric strength.
In addition to the composite fibers having thermal adhesiveness, the web used for producing the air-permeable nonwoven fabric may contain fibers (hereinafter referred to as "non-thermal-adhesive fibers") other than the so-called thermal-adhesive fibers, such as natural fibers (wood fibers, etc.), regenerated fibers (rayon, etc.), semisynthetic fibers (acetate, etc.), chemical fibers, synthetic fibers (polyester, acrylic, nylon, vinyl chloride, etc.), and the like. The "non-heat-bondable fibers" are fibers that do not undergo thermal changes (melting or softening) such as heat bonding in the heat bonding performed in the production of a nonwoven fabric. When the non-heat-bondable fiber is contained, the proportion of the non-heat-bondable fiber to the total weight of the web is not limited as long as the effect of the invention is not impaired, and may be, for example, 1 to 30% by weight, and preferably 3 to 15% by weight.
The shape of the composite fiber may be, for example, a concentric sheath-core type, an eccentric sheath-core type, or a side-by-side type in a cross section perpendicular to the longitudinal direction thereof. In the case of the concentric sheath-core type composite fiber or the eccentric sheath-core type composite fiber, the composite fiber is preferably one in which the low-melting-point component constitutes the sheath component and the high-melting-point component constitutes the core component.
In the case of producing a web using a carding machine using composite fibers as a raw material, the composite fibers need to have crimp. In the case of the concentric sheath-core type composite fiber, a crimper (crimper) may be used to impart mechanical crimping in a zigzag shape. In the case of the eccentric sheath-core type conjugate fiber, mechanical crimping in a zigzag shape may be imparted by a crimper, or three-dimensional crimping may be imparted by a stretching or drying step. The pass through of the carding machine was good if the number of curls was 7.0 peaks/2.54 cm to 20.0 peaks/2.54 cm, and the texture of the web obtained was good if it was 11.0 peaks/2.54 cm to 16.0 peaks/2.54 cm.
The air-permeable nonwoven fabric of the present invention has a thickness of 50gf/cm2Thickness under load to 3.5gf/cm2The ratio of the thickness under load is 0.5 to 0.8. Since the nonwoven fabric is "not easily crushed" and the thickness thereof does not change greatly under low load and high load, the absorbent body and the top sheet can be sufficiently separated from each other, and it is considered that the nonwoven fabric has excellent liquid-returning prevention properties. Among the conventional second sheets, there has been developed a second sheet having a relatively large thickness (e.g., 1mm or more) under a low load and maintaining a constant thickness even when most of the thickness of the low load is crushed under a high load. However, in the present invention, by forming the nonwoven fabric to be thin from the time of low load and to be less likely to be crushed even under high load, the thickness of the absorbent article itself can be reduced when the nonwoven fabric is mounted on the absorbent article, and unevenness in the surface portion of the absorbent article can be suppressed. It is important that the thickness ratio is 0.5 to 0.8, preferably 0.6 to 0.7.
Further, the air-permeable nonwoven fabric of the present invention has a thickness of 50gf/cm2The surface area of the fiber per unit volume under load was 70cm2/cm3～120cm2/cm3The characteristics of (1). Here, the fiber surface area per unit volume was 1cm of the nonwoven fabric3The sum of the surface areas of the fibers contained in (1cc) is based on the surface area of the constituent fibers and the fibers of the nonwoven fabricThe density is measured. The fiber surface area and the fiber surface area per unit volume were calculated by the following formulas (1) and (2).
(1) Fiber surface area (cm)2Weight (g) of fiber diameter (μm) ÷ 10000(μm/cm) × pi × 10000(m) × 100(cm/m) ÷ 10000m of fiber
(2) Surface area of fiber per unit volume (cm)2/cm3) Fiber surface area (cm)2Fiber Density (g/cm) of × nonwoven Fabric3)
Although not particularly limited by theory, in the present invention, it is considered that the fiber surface area per unit volume of the nonwoven fabric under load is related to the capillary phenomenon generated in the nonwoven fabric, and is 50gf/cm2The surface area of the fiber per unit volume under load was 70cm2/cm3～120cm2/cm3In the above range, the absorbent material can exhibit excellent permeability of excretory fluid such as urine, and can suppress liquid return. In particular, when the "degree of flattening" is in a certain range and the fiber surface area per unit volume of the nonwoven fabric is in a certain range, it is considered that the air-permeable nonwoven fabric of the present invention can obtain excellent liquid permeability and can obtain excellent liquid-return prevention properties.
The weight per unit area of the air-permeable nonwoven fabric of the present invention is not limited as long as the above-described structure is satisfied and the effects of the present invention can be obtained, and may be set to 20g/m, for example2～35g/m2More preferably 25g/m2～33g/m2. The air-permeable nonwoven fabric according to the present invention has a low basis weight as the second sheet and excellent liquid-returning prevention properties, and therefore, the overall weight of the absorbent article can be reduced and the absorbent article can be made compact.
The fineness of the fibers constituting the air-permeable nonwoven fabric of the present invention is not limited as long as the fiber satisfies the above-described constitution and the effects of the present invention can be obtained, and for example, the fineness is in the range of 2.0dtex to 20dtex, preferably 3dtex to 15dtex, and more preferably 5dtex to 10 dtex. It is considered that if fibers having a fineness of 20dtex or more are used, the nonwoven fabric becomes a stiff-touch nonwoven fabric, and when the nonwoven fabric is mounted on an absorbent article, the touch of the surface is adversely affected, and if fibers having a fineness of 2.0dtex or less are used, the thickness cannot be maintained under high load, and rewetting is promoted.
The nonwoven fabric of the present invention may contain a deodorizing component, an anti-allergen component, an antibacterial component, a moisturizing component, and the like, within a range not to impair the effects of the present invention. These ingredients can be imparted by the following method: a method of attaching the fibers to a nonwoven fabric by spraying or the like, a method of kneading the fibers into the interior of at least one thermoplastic composite fiber constituting the nonwoven fabric, a method of attaching the fibers to the surface, or the like.
Absorbent articles using the nonwoven fabric of the present invention as the second sheet are used, for example, as diapers such as disposable diapers, diaper pads (pads), menstrual blood absorbent pads, and the like. The absorbent article using the nonwoven fabric of the present invention as the second sheet can have a conventionally known configuration, specifically, for example, the following configuration, in addition to using the air-permeable nonwoven fabric as the second sheet.
The absorbent article includes a top sheet, a second sheet, an absorbent, and a water-resistant back sheet (backsshet). For example, a single layer or a laminated layer of air-permeable nonwoven fabric can be used as the top sheet. The absorption body is typically made of an absorbent material. As the absorbent material, a known absorbent material that can be used in an absorbent article such as a disposable diaper can be used. Specifically, fluff pulp (fluff pulp), Super Absorbent Polymer (SAP), hydrophilic sheet, and the like can be mentioned, and one or more of these can be used.
As the fluff pulp, it is preferable to defibrate wood pulp or non-wood pulp into a cotton-like form. As the SAP, sodium polyacrylate is preferable. As the hydrophilic sheet, a nonwoven fabric may be used in addition to toilet paper (tissue paper) and absorbent paper. When a nonwoven fabric is used, a hydrophilized nonwoven fabric is preferred. Further, as a countermeasure against the running, synthetic fibers such as thermal fusion fibers may be included. These materials may be used alone or in combination, and for example, as a preferable absorbent material, a material containing about 10 to 500 parts by mass of SAP per 100 parts by mass of fluff pulp is used.
The absorbent body is usually used in the form of a single-layer or multi-layer mat (mat). In the case of using fluff pulp in combination with SAP, the SAP may be uniformly mixed in the mat of fluff pulp or may be arranged in layers between layers of fluff pulp. In the case where SAP is used as the absorber as described above, it is preferable that the entire absorber layer is coated with a hydrophilic sheet in order to prevent leakage of SAP from the absorber layer and to impart shape stability to the absorber layer.
On the lower surface side of the absorber, a waterproof back sheet is provided to prevent leakage of the absorbing object to the outside of the absorbent article. The back sheet forms the outermost layer of the absorbent article, and is a layer located on the clothing side of the user when the user wears the absorbent article. Examples of the material constituting the back sheet include liquid-impermeable films made of resins such as polyethylene, and among them, microporous polyethylene films are preferably used. The microporous polyethylene film has many fine pores of 0.1 to several μm and has moisture permeability although it is liquid impermeable, and thus, by using it, it is possible to prevent the interior of the absorbent article from becoming stuffy.
Further, a cover sheet (cover sheet) including a paper cloth (cloth), a woven fabric, a spunlace nonwoven fabric, a spunbonded nonwoven fabric, or the like may be provided on the outermost surface of the back sheet in order to provide a water-repellent film for reinforcement or to improve the hand feeling during use. Among them, a spunbond nonwoven fabric is suitably used in terms of strength or cost.
In addition, the absorbent article may also have a fixing member for preventing shifting of the absorbent article. The fixing member may be, for example, an adhesive tape, and may be provided at one or more locations on the outermost surface of the absorbent article. In addition, for example, any of various structures such as an extensible tape, an extensible tape (tape), and a pleat for forming a three-dimensional shape may be provided according to the purpose.
(production method)
The nonwoven fabric of the present invention is a breathable nonwoven fabric, and a method for producing a web can be obtained by appropriately selecting known methods and conditions. As described above, it is preferable to produce a web using a composite fiber having thermal adhesiveness, which is a composite of a plurality of resins having different melting points. The obtained web was placed on a conveying support (belt conveyor) and sent to a heat treatment apparatus. In the heat treatment apparatus, heating is performed to a temperature at which only the low-melting-point resin of the conjugate fibers melts, the molten low-melting-point resins are bonded (thermally bonded) to each other, whereby the intersections of the fibers are welded, and then cooling is performed, thereby producing an air-permeable nonwoven fabric having a three-dimensional structure. In the present invention, it is preferable that the low-melting-point resin of the fibers is melted in the heat treatment machine, and the web is pressed with a roller or a plate, for example, to forcibly contact the fibers with each other and thermally bond the fibers. The compacting may be performed after the heat treatment, and is preferably performed immediately after the heat treatment. Through the steps, the non-woven fabric with increased bonding points and low possibility of being crushed under high load can be obtained.
[ examples ]
The present invention will be described in more detail below with reference to examples, but the following examples are only for illustrative purposes. The scope of the present invention is not limited to the present embodiment.
The methods for measuring the physical property values used in examples and comparative examples and the definitions thereof are shown below.
< weight per unit area of nonwoven Fabric >
The weight of the nonwoven fabric was measured by cutting it into a 10cm × 10cm square, and the weight was calculated by converting it into a corresponding value per unit area and rounding it to the first decimal place.
Thickness of nonwoven Fabric
The nonwoven fabric was cut into 10cm × 10cm squares, and the product was obtained using a 2cm portable compressor KES-G5 (trade name) manufactured by KatoTech2The press plate (3) was used to compress the nonwoven fabric and the resultant was measured for 3.5gf/cm2、50gf/cm2The respective thicknesses are as follows.
< thickness ratio of non-woven fabric >
Is 50gf/cm2The thickness under load was 3.5gf/cm2The ratio of the thickness under load is represented by the following formula.
Thickness ratio of 50gf/cm2Thickness under load ÷ 3.5gf/cm2Thickness under load
＜50gf/cm2Fiber surface area per unit volume of loaded nonwoven fabric
The fiber surface area was calculated from the fiber diameter of the conjugate fiber constituting the nonwoven fabric. The fiber diameter was obtained by taking a magnified photograph of the surface of the nonwoven fabric using a Scanning Electron Microscope (SEM), and the diameters of 20 fibers were measured and the arithmetic average value thereof was used. The fiber surface area and the fiber surface area per unit volume were calculated by the following formulas (1) and (2).
(1) Fiber surface area (cm)2Weight (g) of fiber diameter (μm) ÷ 10000(μm/cm) × pi × 10000(m) × 100(cm/m) ÷ 10000m of fiber
(2) Surface area of fiber per unit volume (cm)2/cm3) Fiber surface area (cm)2Fiber Density (g/cm) of × nonwoven Fabric3)
By multiplying the surface area of the fiber by 50gf/cm2The density of the nonwoven fabric under load was calculated to be 50gf/cm2Fiber surface area per unit volume (cm) of nonwoven fabric under load2/cm3)。
< liquid Return test >
Evaluation was carried out by a method according to European nonwoven Association (EDANA) -ERT 151.1-96. The absorbent paper used was prepared by cutting a Kimtosel towel (trade name) made of Crecia (Strand) to about 90mm × 90mm (adjusted to 5.00g to 5.05g), and then allowing 15ml of physiological saline to permeate and absorb. The amount of return liquid was determined according to the following criteria. The smaller the amount of the return liquid, the better the nonwoven fabric was judged to be.
O: less than 2.0g
And (delta): 2.0g or more and less than 3.0g
X: 3.0g or more
[ example 1]
A sheath-core type conjugate fiber having a fineness of 5.6dtex, a sheath component of polyethylene and a core component of polyethylene terephthalate and a weight per unit area of 31g/m was produced2The nonwoven fabric of (1). First, the composite fiber is made into a web by a carding method. Using heat at 138 ℃The web is produced by passing hot air through the obtained web by an air circulation type suction belt dryer (suction belt dryer), bonding the inter-fiber entanglement points constituting the web, and then immediately compressing the web by a metal roll to forcibly promote thermal bonding between the fibers.
The non-woven fabric has a non-woven fabric thickness ratio of 0.69 to 50gf/cm2The surface area of the fiber per unit volume under load was 95cm2/cm3Good results were obtained with a reflux of 1.6 g.
[ examples 2 to 3]
The nonwoven fabrics described in table 1 were produced in the same manner as in example 1 using the concentric sheath-core thermal adhesive conjugate fibers described in table 1. The results of the evaluation in the same manner as in example 1 are shown in table 1. Further, as a raw material fiber, a sheath-core type conjugate fiber having 9.0dtex in example 2 and 20dtex in example 3, a polyethylene as a sheath component and polyethylene terephthalate as a core component was used as a raw material of a nonwoven fabric.
Liquid return is inhibited and good results are obtained.
Comparative example 1
A sheath-core type conjugate fiber having a fineness of 5.6dtex, a sheath component of polyethylene and a core component of polyethylene terephthalate and a basis weight of 30g/m was produced2The nonwoven fabric of (1). First, the composite fiber is made into a web by a carding method. The web thus obtained was passed through hot air by means of a hot air circulation type suction belt dryer at 138 ℃ to bond the inter-fiber entanglement points constituting the web. Thereafter, a nonwoven fabric was produced without compressing the web using a metal roll.
The non-woven fabric has a non-woven fabric thickness ratio of 0.12 to 50gf/cm2The surface area of the fiber per unit volume under load was 555cm2/cm3The reflux was 2.6g, and poor results were obtained.
Comparative examples 2 to 3
The nonwoven fabrics described in table 1 were produced in the same manner as in comparative example 1 using the concentric sheath-core thermal adhesive conjugate fibers described in table 1. The results of the evaluation in the same manner as in comparative example 1 are shown in table 1. Further, as a raw material fiber, a sheath-core type conjugate fiber having 5.6dtex in comparative example 2 and 9.0dtex in comparative example 3, and a polyethylene as a sheath component and polyethylene terephthalate as a core component was used as a raw material of a nonwoven fabric. No reversion could be inhibited and poor results were obtained.
[ Table 1]
Figure BDA0002423409170000101
Example 1 and comparative example 1, and example 2 and comparative example 3 are examples in which the fibers constituting the nonwoven fabric are the same and are different only in that the non-crimping treatment is performed after the production of the air-permeable nonwoven fabric. As shown in Table 1, it was found that each of example 1 and comparative example 1, and example 2 and comparative example 3 was 3.5gf/cm2The thickness under load was approximately the same, but 50gf/cm2The nonwoven fabrics of examples 1 and 2 were not easily crushed even under load, and the fiber surface area per unit volume was maintained within a certain range under load, since the thicknesses were greatly different under load. As shown in Table 1, the thickness ratio of the non-woven fabric of the air-permeable non-woven fabric was adjusted to 50gf/cm2The surface area of the fiber per unit volume under load is controlled to a predetermined range, and liquid return can be greatly suppressed.
[ industrial applicability ]
The air-permeable nonwoven fabric of the present invention can be used as a second sheet to be mounted on a diaper such as a disposable diaper, a urine pad, a menstrual blood absorption pad, or the like.

Claims (5)

1. A gas-permeable nonwoven fabric containing 50gf/cm2Thickness under load to 3.5gf/cm2The ratio of the thickness under load is 0.5 to 0.8, and 50gf/cm2The surface area of the fiber per unit volume under load was 70cm2/cm3～120cm2/cm3。
2. The breathable nonwoven fabric of claim 1, having a weight per unit area of 20g/m2～35g/m2。
3. The breathable nonwoven fabric according to claim 1 or 2, comprising composite fibers comprising polyethylene terephthalate and polyethylene, and being any one selected from the group consisting of side-by-side composite fibers, eccentric sheath-core composite fibers, and concentric sheath-core composite fibers.
4. A method for producing the air-permeable nonwoven fabric according to any one of claims 1 to 3, comprising:
a step of making a web of composite fibers, the composite fibers including polyethylene terephthalate and polyethylene and being any one selected from the group consisting of side-by-side composite fibers, eccentric sheath-core composite fibers, and concentric sheath-core composite fibers;
a heat treatment step of heat-treating the mesh obtained in the step by a ventilation method; and
a step of compacting the web immediately after the heat treatment step.
5. An absorbent article comprising the breathable nonwoven fabric according to any one of claims 1 to 3.
CN202010212881.9A 2019-03-28 2020-03-24 Air-permeable nonwoven fabric, method for producing same, and absorbent article Pending CN111748910A (en)

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