GB2581560A - Air-through nonwoven fabric for absorbent article - Google Patents

Air-through nonwoven fabric for absorbent article Download PDF

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Publication number
GB2581560A
GB2581560A GB1918330.0A GB201918330A GB2581560A GB 2581560 A GB2581560 A GB 2581560A GB 201918330 A GB201918330 A GB 201918330A GB 2581560 A GB2581560 A GB 2581560A
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GB
United Kingdom
Prior art keywords
nonwoven fabric
fibre
air
layer
less
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
GB1918330.0A
Other versions
GB201918330D0 (en
GB2581560B (en
Inventor
Komori Yasuhiro
Sangawa Yuta
Taneichi Shoichi
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.)
Kao Corp
Original Assignee
Kao 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
Application filed by Kao Corp filed Critical Kao Corp
Publication of GB201918330D0 publication Critical patent/GB201918330D0/en
Publication of GB2581560A publication Critical patent/GB2581560A/en
Application granted granted Critical
Publication of GB2581560B publication Critical patent/GB2581560B/en
Active legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • 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
    • 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
    • A61F13/15577—Apparatus or processes for manufacturing
    • A61F13/15699—Forming webs by bringing together several webs, e.g. by laminating or folding several webs, with or without additional treatment of the webs
    • 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
    • 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
    • A61F13/5116—Topsheet, i.e. the permeable cover or layer facing the skin being formed of multiple layers
    • 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
    • A61F13/513—Topsheet, i.e. the permeable cover or layer facing the skin characterised by its function or properties, e.g. stretchability, breathability, rewet, visual effect; having areas of different permeability
    • 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
    • A61F13/514—Backsheet, i.e. the impermeable cover or layer furthest from the skin
    • A61F13/51456—Backsheet, i.e. the impermeable cover or layer furthest from the skin characterised by its properties
    • A61F13/51458—Backsheet, i.e. the impermeable cover or layer furthest from the skin characterised by its properties being air-pervious or breathable
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
    • B32B5/22—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed
    • B32B5/24—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer
    • B32B5/26—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by the presence of two or more layers which are next to each other and are fibrous, filamentary, formed of particles or foamed one layer being a fibrous or filamentary layer another layer next to it also being fibrous or filamentary
    • 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
    • D04H1/4374—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 using different kinds of webs, e.g. by layering webs
    • 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
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/54—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving
    • D04H1/541—Composite fibres, e.g. sheath-core, sea-island or side-by-side; Mixed fibres
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/54—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving
    • D04H1/541—Composite fibres, e.g. sheath-core, sea-island or side-by-side; Mixed fibres
    • D04H1/5412—Composite fibres, e.g. sheath-core, sea-island or side-by-side; Mixed fibres sheath-core
    • D—TEXTILES; PAPER
    • D04—BRAIDING; LACE-MAKING; KNITTING; TRIMMINGS; NON-WOVEN FABRICS
    • D04H—MAKING TEXTILE FABRICS, e.g. FROM FIBRES OR FILAMENTARY MATERIAL; FABRICS MADE BY SUCH PROCESSES OR APPARATUS, e.g. FELTS, NON-WOVEN FABRICS; COTTON-WOOL; WADDING ; NON-WOVEN FABRICS FROM STAPLE FIBRES, FILAMENTS OR YARNS, BONDED WITH AT LEAST ONE WEB-LIKE MATERIAL DURING THEIR CONSOLIDATION
    • D04H1/00—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres
    • D04H1/40—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties
    • D04H1/54—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving
    • D04H1/559—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres from fleeces or layers composed of fibres without existing or potential cohesive properties by welding together the fibres, e.g. by partially melting or dissolving the fibres being within layered webs
    • 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
    • D04H1/70—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres
    • D04H1/72—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged
    • D04H1/732—Non-woven fabrics formed wholly or mainly of staple fibres or like relatively short fibres characterised by the method of forming fleeces or layers, e.g. reorientation of fibres the fibres being randomly arranged by fluid current, e.g. air-lay
    • 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
    • A61F13/15577—Apparatus or processes for manufacturing
    • A61F2013/15821—Apparatus or processes for manufacturing characterized by the apparatus for manufacturing
    • A61F2013/15934—Apparatus or processes for manufacturing characterized by the apparatus for manufacturing for making non-woven
    • 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
    • A61F13/5116—Topsheet, i.e. the permeable cover or layer facing the skin being formed of multiple layers
    • A61F2013/51178—Topsheet, i.e. the permeable cover or layer facing the skin being formed of multiple layers with the combination of nonwoven webs
    • 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
    • A61F13/514—Backsheet, i.e. the impermeable cover or layer furthest from the skin
    • A61F13/51401—Backsheet, i.e. the impermeable cover or layer furthest from the skin characterised by the material
    • A61F2013/51441—Backsheet, i.e. the impermeable cover or layer furthest from the skin characterised by the material being a fibrous material
    • A61F2013/51447—Backsheet, i.e. the impermeable cover or layer furthest from the skin characterised by the material being a fibrous material being air permeable
    • 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
    • A61F13/514—Backsheet, i.e. the impermeable cover or layer furthest from the skin
    • A61F13/51401—Backsheet, i.e. the impermeable cover or layer furthest from the skin characterised by the material
    • A61F2013/51441—Backsheet, i.e. the impermeable cover or layer furthest from the skin characterised by the material being a fibrous material
    • A61F2013/51452—Backsheet, i.e. the impermeable cover or layer furthest from the skin characterised by the material being a fibrous material being nonwovens

Landscapes

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

Abstract

An air-through nonwoven fabric (10) in which two or more fiber layers (1, 2) are laminated, wherein the air-through nonwoven fabric (10) for an absorbent article contains thermoplastic fibers and has at least one fiber layer (8) having fiber masses (7).

Description

DESCRIPTION
TITLE OF THE INVENTION: AIR-THROUGH NONWOVEN FABRIC FOR ABSORBENT ARTICLE
FIELD OF THE INVENTION
The present invention relates to an air-through nonwoven fabric for an absorbent article.
BACKGROUND OF THE INVENTION
An air-through nonwoven fabric is formed by thermally fusing fibre intersections with each other by hot air blowing using an air-through method, thereby enabling the air-through nonwoven fabric to be relatively easily thickened into an excellent texture material. Such air-through nonwoven fabrics are often used as components of absorbent articles. Various proposals have in the past been offered regarding such air-through nonwoven fabric for use in absorbent articles.
For example, with a view to achieving an aesthetic pattern effect without adversely affecting texture, Patent Literature 1 describes an air-through nonwoven fabric in which difference between thickness at a site having small fibre mass and thickness at a site not having small fibre mass under a pressure of 7.64 kPa is adjusted to 1 mm or less. Application of calendering to a preliminary nonwoven fabric obtained by hot air blowing treatment is described as a method of producing this air-through nonwoven fabric. Patent Literature 2 describes an absorbent article incorporating a nonwoven fabric having thermoplastic synthetic fibres and organic cotton fibres. In this nonwoven fabric, the organic cotton fibres are arranged to form a plurality of fibre masses. The organic cotton fibres are retained in the nonwoven fabric by entanglement of the fibres without thermal fusion.
With a view to improving nonwoven fabric texture, Patent Literature 3 proposes that pressure application treatment is performed on a completed nonwoven fabric between a pair of rolls at a specific linear pressure and a specific temperature.
Patent Literature 4 describes a processing method in which a wound fibre sheet in roll shape is unwound, and hot air is blown using an air-through method to apply calendering thereto at a specific linear pressure.
CITATION LIST
PATENT LITERATURES {0003} Patent Literature 1: JP-A-2013-151774 ("JP-A" means unexamined published Japanese patent application) Patent Literature 2: JP-A-2017-202265 Patent Literature 3: JP-A-60-126365 Patent Literature 4: JP-A-2006-299480
SUMMARY OF THE INVENTION
The present invention provides an air-through nonwoven fabric for an absorbent article, in which two or more fibre layers are laminated, containing at least one fibre layer containing thermoplastic fibres and a fibre mass portion.
Further, the present invention provides a method of producing an air-through nonwoven fabric for an absorbent article, containing: an opening step in which a plurality of times of opening treatment are applied to thermoplastic fibres to form a web; a step in which a plurality of single-layer webs obtained in the opening step are laminated to form a laminated web, and air-through processing by hot air is applied to the laminated web to obtain an air-through nonwoven fabric; and a calendering step in which calendering is applied to one or more of sheets selected from the single-layer web, the laminated web and the air-through nonwoven fabric by using a pair of calender rolls.
Other and further objects, features and advantages of the invention will appear more fully from the following description, appropriately referring to the accompanying drawings.
BRIEF DESCRIPTION OF DRAWINGS
{0007} {FIG 1} FIG. 1 is a cross-sectional view schematically showing one preferred embodiment of an air-through nonwoven fabric for an absorbent article according to the present invention.
{FIG. 2} FIG. 2 is a schematic configuration diagram showing one preferred embodiment of a method of producing a nonwoven fabric and a production apparatus therefor according to the present invention.
{FIG. 3} FIG. 3 is a schematic configuration diagram showing another preferred embodiment of a heat treatment unit for performing an air-through step in this embodiment.
DESCRIPTION OF EMBODIMENTS
The present invention relates to an air-through nonwoven fabric for an absorbent article formed into a material having excellent bulkiness and soft texture, and provided with a pattern.
In a step of producing the air-through nonwoven fabric, upon opening fibres to form a web, the fibres are mutually entangled, whereby fibre masses are occasionally formed locally. Of particular interest is that the aforesaid fibre masses occur more easily in proportion as fibre diameter decreases. If this fibre mass is directly subjected to an air-through processing step by hot air, the fibre mass is hardened by thermal fusion of the fibres.
Meanwhile, as described in Patent Literatures 1, 3 and 4 discussed above, the practice has so far been to perform calendering on a completed nonwoven fabric to reduce hardness. However, the calendering is a treatment in which the air-through nonwoven fabric is interposed between a pair of rolls to apply pressure thereto, and the air-through nonwoven fabric after pressure application is thinned, thereby leaving room for improvement in bulkiness. Even if hot air treatment is performed after calendering the nonwoven fabric as described in Patent Literatures 1, 3 and 4 described above, there is a limit to recovery of thickness of the once flattened nonwoven fabric, so that further room for improvement remains in this aspect as well. In this regard, the aforesaid Patent Literature 3 offers no suggestion regarding recovery of bulkiness In an air-through nonwoven fabric for absorbent articles, it is strongly desired to realise both satisfactory bulkiness and soft texture to achieve a superior material from the viewpoints of absorption and cushioning properties and the like of the absorbent article.
In contrast, the air-through nonwoven fabric for an absorbent article according to the present invention is formed into a material that is excellent in bulkiness and soft texture, and is provided with a pattern. Moreover, according to a producing method of the present invention, the aforesaid air-through nonwoven fabric for an absorbent article can be produced to a high degree of perfection.
Hereinafter, the air-through nonwoven fabric for an absorbent article according to the present invention will be described with reference to drawings. The air-through nonwoven fabric for an absorbent article according to the present invention can be applied to various absorbent articles worn to a body to absorb a bodily fluid, and can be applied to various components such as a topsheet in the absorbent article.
In the present invention, unless otherwise specified, a side in contact with a human body is referred to as a skin surface side, a skin-contact surface side or a surface side, and a side opposite thereto is referred to as a non-skin surface side, a skin non-contact surface side or a back surface side.
The term "air-through nonwoven fabric" in the present invention is a material in which thermally fusible fibres are thermally fused with each other at intersections and integrated. An air-through method is used for producing this nonwoven fabric. The air-through method means a method in which hot air is blown onto a fibre web containing the thermally fusible fibres by a pass-through method to fuse the intersections among the webs with each other, thereby forming the nonwoven fabric.
{0013} The air-through nonwoven fabric for an absorbent article according to the present invention is an air-through nonwoven fabric in which two or more fibre layers are laminated. The fibre layers to be laminated may be in two layers or in three or more layers. The air-through nonwoven fabric for an absorbent article according to the present invention has two or more layers, whereby the air-through nonwoven fabric can be formed into a further bulky nonwoven fabric beyond production restriction in comparison with the case where the nonwoven fabric is formed by one layer.
FIG. 1 shows, as a preferred embodiment of the air-through nonwoven fabric for an absorbent article according to the present invention, an air-through nonwoven fabric 10 for an absorbent article in which two fibre layers (a fibre layer 1 and a fibre layer 2) are laminated (hereinafter, referred to simply as a nonwoven fabric 10). The fibre layer 1 and the fibre layer 2 include thermally fusible fibres, in which contact surfaces of both the layers are bonded over a whole area by fusion of the thermally fusible fibres with each other. Therefore, the nonwoven fabric 10 does not have such a region in which the fibre layer 1 and the fibre layer 2 are separated from each other. That is, the nonwoven fabric is one sheet body in which the two layers described above are integrated. {0015} The nonwoven fabric of the present invention may have various surface shapes such as an uneven surface. However, as the nonwoven fabric 10 of this embodiment shown in FIG. 1, both surfaces 10A and 10B (a surface of the fibre layer 1 and a surface of the fibre layer 2) preferably have a flat shape. The nonwoven fabric 10 is a laminate of a plurality of fibre layers, and both the surfaces have the flat shape, whereby both surface smoothness and a cushion feeling are satisfied into an excellent material. The term "flat shape" means a shape in which a difference of thickness between a concave portion and a convex portion on a surface of the nonwoven fabric is within 1 mm. Specifically, the nonwoven fabric is cut in a thickness direction by using a razor edge to take a photograph of a cross section by using Microscope (VHX-900, manufactured by Keyence Corporation). In the photograph, a thickness of a part in which a top surface of the nonwoven fabric is located on an uppermost side, namely, the convex portion, and a thickness of a part in which the top surface of the nonwoven fabric is located on a lowermost side, namely, the concave portion are measured to calculate this difference of thickness, whereby the difference of thickness can be determined. An average value of three points is taken as the difference of thickness.
The nonwoven fabric 10 has at least one fibre layer 8 containing a fibre mass portion 7. Hereinafter, the fibre layer 8 containing a fibre mass portion 7 is referred to as a fibre mass layer 8. In FIG. 1, the fibre mass layer 8 is arranged in the fibre layer 1.
In the present invention, the term "fibre mass portion" means a part of a knot (mass of fibres) formed by entanglement of the fibres in the fibre layer. The fibre mass portion can be recognised as the mass (granular form) in which density of the fibres is increased than in a peripheral part in the same fibre layer, and concentration (lightness) of colour (mainly white) of the fibres is visually increased than in the peripheral part. A shape of the fibre mass portion is not particularly limited. In the present invention, it is preferable that the fibre mass portion is formed into a flattened shape in which the fibres are flattened in the thickness direction of the nonwoven fabric when observed from the cross section of the nonwoven fabric in the thickness direction, and a surface of the fibre mass portion on a side of a nonwoven fabric surface has a smooth structure. Thus, the surface of the nonwoven fabric corresponding to a position in which the fibre mass portion 7 is present is smoothened, whereby surface texture of the nonwoven fabric 10 is felt to be superior.
The term "fibre mass layer 8" described above means a layer containing one or more fibre mass portions. The fibre mass layer 8 is not necessarily filled with the fibre mass portion 7, and is preferably arranged with the fibre mass portion 7 in a dispersed manner.
{0019} The fibre mass layer 8 is not limited to the case where the fibre mass layer 8 is present only in the fibre layer 1 as shown in FIG. 1, and may be present in the fibre layer 2 instead of the fibre layer 1 or in both the layers. From a viewpoint of the soft texture, the fibre mass layer 8 is preferably present in either one of the layers. From a viewpoint of enhancing a visual effect by the pattern of the fibre mass portion 7 in a plane view of the nonwoven fabric 10, the fibre mass layers 8 are preferable present in both the layers. Thus, the pattern formed by the fibre mass portion 7 is visible in the dispersed manner not only in a plane direction of the nonwoven fabric 10 but also in the thickness direction thereof, and as the pattern is present on a lower layer side, a concentration of the fibre mass portion 7 visible in the thickness direction is viewed to change in a thinner manner, whereby a deep pattern can be viewed. When the fibre mass layers 8 are present in both the layers of the fibre layer 1 and the fibre layer 2, the fibre mass portion 7 in the fibre layer 1 and the fibre mass portion 7 in the fibre layer 2 are preferably arranged so as not to overlap in the thickness direction. Moreover, the fibre mass layer 8 may be wholly or partly arranged in the fibre layer (fibre layer 1 or fibre layer 2) in which the fibre mass layer 8 is arranged.
As mentioned above, the nonwoven fabric 10 is formed by fusing and integrating the fibres with each other in a layer interface in the whole area in which the fibre layer 1 and the fibre layer 2 are contacted. Therefore, even if the nonwoven fabric 10 contains the fibre mass layer 8 containing the fibre mass portion 7, the nonwoven fabric 10 as a whole, in which a plurality of fibre layers is integrated in the layer interface as a whole, is felt to be thick into a material excellent in the bulkiness and the soft texture. Then, in the plane view of the nonwoven fabric 10, the nonwoven fabric 10 is formed into the material provided with the pattern caused by a difference of variable concentration of colour between parts with and without the fibre mass portion. The nonwoven fabric 10 is formed into a material provided with aesthetics by the pattern formed by this fibre mass portion 7, particularly the pattern formed by the fibre mass portion 7 in which the thickness is reduced.
The nonwoven fabric 10 of this embodiment preferably has fine fibres having a fibre diameter of 1 dtex or more and 2.2 dtex or less, and thick fibres having a fibre diameter larger than the fine fibres. Thus, both improvement in the soft texture of the nonwoven fabric by the fine fibres and improvement in the bulkiness by the thick fibres can be satisfied. Moreover, the nonwoven fabric 10 has the thick fibres, whereby the nonwoven fabric 10 can also contribute to improvement in thickness recoverability of the nonwoven fabric after pressure application, and such a case is preferable.
In addition, the fibre mass layer 8 preferably includes the fine fibres described above. In this case, the fine fibres described above may be contained in the fibre mass portion 7 or may be contained in a part other than the fibre mass portion 7. Thus, the hardness around the fibre mass portion 7 felt upon contacting with the nonwoven fabric 10 is relaxed by presence of the fine fibres described above. In this case, in the nonwoven fabric 10, the fibre layer 1 having the fibre mass layer 8 including the fine fibres described above is preferably arranged toward the skin-contact surface side in the absorbent article. {0023} From a viewpoint of improving the soft texture of the nonwoven fabric 10, the fibre diameter of the fine fibres described above is more preferably 2 dtex or less, and further preferably 1.5 dtex or less. From a viewpoint of spinnability in a carding machine in nonwoven fabric production, the fibre diameter of the fine fibres described above is more preferably 1 dtex or more, and further preferably 1.2 dtex or more. Specifically, the fibre diameter of the fine fibres is preferably 1 dtex or more and 2 dtex or less, and more preferably 1.2 dtex or more and 1.5 dtex or less.
From a viewpoint of improving the soft texture of the nonwoven fabric 10, a content of the fine fibres described above in the fibre mass layer 8 is preferably 50% by mass or more, more preferably 80% by mass or more, and further preferably 100% by mass in terms of a mass proportion.
The nonwoven fabric 10 of this embodiment preferably has at least one fibre layer 9 containing no fibre mass portion 7 (hereinafter, referred to as non-fibre mass layer 9) in addition to the fibre mass layer 8 mentioned above. For example, as shown in FIG. 1, specific examples thereof include an aspect in which a fibre layer 1 is a fibre mass layer 8, and a fibre layer 2 is a non-fibre mass layer 9.
{0026} When the nonwoven fabric 10 has the fibre mass layer 8 and the non-fibre mass layer 9, it is preferable that the nonwoven fabric 10 has thick fibres having a fibre diameter of more than 2.2 dtex and 7 dtex or less, and fine fibres having a fibre diameter smaller than the thick fibres. The fibre diameter of the fine fibres is preferably in the range mentioned above. Thus, both the improvement in the soft texture of the nonwoven fabric by the fine fibres and the improvement in the bulkiness by the thick fibres can be satisfied, whereby the nonwoven fabric 10 can also contribute to the improvement in thickness recoverability of the nonwoven fabric after pressure application, and such a case is preferable.
The non-fibre mass layer 9 preferably includes the thick fibres described above. The non-fibre mass layer 9 includes the thick fibres described above, whereby such a configuration can improve the bulkiness and provide the nonwoven fabric 10 with the cushion feeling. In this case, in the nonwoven fabric 10, the fibre layer 2 having the non-fibre mass layer 9 including the thick fibres is preferably arranged toward a skin non-contact surface side in the absorbent article.
From a viewpoint of improving the bulkiness and compression recoverability of the nonwoven fabric 10, the fibre diameter of the thick fibres described above is more preferably more than 2.2 dtex, and further preferably 4.4 dtex or more. From a viewpoint of a feeling from a fibre mass layer side, the fibre diameter of the thick fibres described above is more preferably 5.5 dtex or less, and further preferably 5 dtex or less. Specifically, the fibre diameter of the thick fibres is preferably more than 2.2 dtex and 5.5 dtex or less, and more preferably 4.4 dtex or more and 5 dtex or less.
{0029} From a viewpoint of improving the bulkiness and compression recoverability of the nonwoven fabric 10, a content of the thick fibres described above in the non-fibre mass layer 9 is preferably 50% by mass or more, more preferably 80% by mass or more, and further preferably 100% by mass in terms of a mass proportion.
From a viewpoint of improving the soft texture of the nonwoven fabric 10, a content of the thick fibres described above in the fibre mass layer 8 is preferably 50% by mass or less, more preferably 30% by mass or less, and further preferably 10% by mass or less in terms of a mass proportion.
(Method of measuring fibre diameter of fine fibres and thick fibres, method of measuring content of fine fibres in fibre mass layer 8, and method of measuring content of thick fibres in non-fibre mass layer 9) From an arbitrary place of the nonwoven fabric, three places on a side of the fibre mass layer and a surface side of the non-fibre mass layer are magnified and observed at a magnification of 100 using a scanning electron microscope (JCM-5100, manufactured by JEOL Ltd.).
Fibre diameter: A fibre diameter within an area range of 1 mm2 is measured. Measurement of the fibre diameter is performed on 20 points for each different fibre per place, and an average value is taken as each fibre diameter. In addition, a fluctuation range of the fibre diameter in the nonwoven fabric for an absorbent article is ordinarily in a fine difference which is hard to be confirmed even by observation using the scanning electron microscope described above. For example, the fluctuation range of the fibre diameter is generally about 6% according to the specification of fibres. Accordingly, if the value obtained by measuring the diameters in 20 points and averaging the data as described above is adopted, the value can be taken as each fibre diameter.
Content ratio of fibres: An OHP film is placed on a photograph within 1 mm2 previously magnified and observed, and then a plane is painted in black for each fibre diameter. Image analysis processing is performed on this sheet by using image analysis software (NexusNewOube). Binarisation processing is performed to determine an area. Each fibre area is measured, and a proportion obtained is taken as a content ratio of each fibre.
(Method of sampling measuring member) When a component (for example, a surface material) to be measured is taken out from an absorbent article to perform evaluation measurement upon the measurement described above, a sample is obtained by the following method. That is, when the component is fixed to any other component by an adhesive or the like, the adhesive is cooled with liquid nitrogen to facilitate to peel the component. When the component is fixed to any other component by fusion or the like, the component is peeled off by hand, or a fused part is cut by a cutter knife or the like to peel the component to perform measurement. This method is used in the same manner also in other measuring methods.
{0033} In the nonwoven fabric 10, an average fibre diameter in the non-fibre mass layer 9 is preferably larger than an average fibre diameter in the fibre mass layer 8. Thus, the fibre mass layer 8 serves as a layer for improving the soft texture of the nonwoven fabric 10, and the non-fibre mass layer 9 serves as a layer for improving the bulkiness and thickness recoverability of the nonwoven fabric 10. As a result, the fibre mass layer Band the non-fibre mass layer 9 can share a function in a layer unit for the nonwoven fabric 10, and also both the layers can collaborate in the thickness direction to further improve the feeling of the nonwoven fabric 10 as a whole. In this respect, it is preferable that the nonwoven fabric 10 has the fine fibres described above and the thick fibres described above, and the fibre mass layer 8 includes the fine fibres described above because the action described above can be further clearly exhibited. From the same viewpoint, it is more preferable that the non-fibre mass layer 9 includes the thick fibres described above.
{0034} From a viewpoint of sharing the function described above in the nonwoven fabric, a difference V3 (= V1 -V2) between the average fibre diameter V1 of the non-fibre mass layer 9 and the average fibre diameter V2 of the fibre mass layer 8 is preferably more than 0 dtex, more preferably 2.2 dtex or more, and further preferably 3 dtex or more. Moreover, from the same viewpoint described above, the difference V3 is preferably 5.6 dtex or less, more preferably 4 dtex or less, and further preferably 3.5 dtex or less. Specifically, the difference V3 is preferably more than 0 dtex and 5.6 dtex or less, more preferably 2.2 dtex or more and 4 dtex or less, and further preferably 3 dtex or more and 3.5 dtex or less.
(Method of measuring average fibre diameter of fibre mass layer 8 and non-fibre mass layer 9) The fibre diameters and the content ratios determined based on the (Method of measuring fibre diameter of fine fibres and thick fibres, method of measuring content of fine fibres in fibre mass layer 8, and method of measuring content of thick fibres in non-fibre mass layer 9) described above are multiplied, and a sum of the resulting values is taken as an average fibre diameter of each layer.
In the nonwoven fabric 10, a basis weight in the non-fibre mass layer 9 is preferably larger than a basis weight in the fibre mass layer 8. Thus, the non-fibre mass layer 9 becomes more bulky than the fibre mass layer 8, and the hardness by the fibre mass portion 7 becomes harder to be felt. The bulkiness of the non-fibre mass layer 9 acts so as to increase the cushioning properties of the nonwoven fabric 10 as a whole, whereby stress given to skin by the fibre mass portion 7 when the fibre mass layer 8 is flattened in the thickness direction can be further reduced to further improve a good feeling. It can further clearly exhibit the action described above that, together with this difference of basis weight, the nonwoven fabric 10 has the fine fibres described above and the thick fibres described above, and the fibre mass layer 8 includes the fine fibres described above, and therefore such a case is preferable. From the same viewpoint, it is more preferable that the non-fibre mass layer 9 includes the thick fibres described above. It is preferable that the nonwoven fabric 10 has a larger average fibre diameter in the non-fibre mass layer than in the fibre mass layer 8.
{0037} From a viewpoint of the cushioning properties and improving the good feeling of the nonwoven fabric as a whole described above, a difference Y3 (= Y1 -Y2) between the basis weight Y1 of the non-fibre mass layer 9 and the basis weight Y2 of the fibre mass layer 8 is preferably more than 0 g/m2, more preferably 3 g/m2 or more, and further preferably 5 g/m2 or more. From the viewpoint of improving the good feeling, the difference Y3 is preferably 20 g/m2 or less, more preferably 15 g/m2 or less, and further preferably 10 g/m2 or less. Specifically, the difference Y3 is preferably more than 0 g/m2 and 20 g/m2 or less, more preferably 3 g/m2 or more and 15 g/m2 or less, and further preferably 5 g/m2 or more and 10 g/m2 or less.
(Method of measuring basis weight of fibre mass layer 8 and non-fibre mass layer 9) 1) A value obtained by converting mass of the nonwoven fabric to be measured into a value per 1 m2 is taken as a whole basis weight.
Mass (w) of the nonwoven fabric to be measured is measured, and then a value calculated by the following equation is taken as a whole basis weight (VV). W = (1000000/LMD/LCD)w = 25w [MD: Machine direction length of the nonwoven fabric to be measured 250 mm LCD: Cross direction length of the nonwoven fabric to be measured 160 mm When a sample is unable to be taken at the size described above upon taking a sample from a product, the sample is cut in the range in which the sample can be taken, and data obtained is converted into a value per 1 m2.
2) Basis weight of each layer: Each layer of the nonwoven fabric to be measured is carefully peeled, and a value obtained by converting the mass into a value per 1 m2 is taken as a basis weight of each layer.
[Unit: Number of digits] g/m2: A value at a second decimal place is rounded off to calculate a value at a first decimal place.
[Number of measurements]: Measurement is performed on three points, and an average value thereof is taken as each basis weight.
From a viewpoint of forming a material provided with excellent bulkiness and soft texture, and the good feeling in a structure in which two or more fibre layers are laminated and integrated, a basis weight of the nonwoven fabric 10 as a whole is preferably 15 g/m2 or more, more preferably 18 g/m2 or more, and further preferably 20 g/m2 or more. From a viewpoint of spinning capability in nonwoven fabric production, the basis weight of the nonwoven fabric 10 as a whole is preferably 40 g/m2 or less, more preferably 30 g/m2 or less, and further preferably 25 g/m2 or less. Specifically, the basis weight of the nonwoven fabric 10 as a whole is preferably 15 g/m2 or more and 40 g/m2 or less, more preferably 18 g/m2 or more and 30 g/m2 or less, and further preferably 20 /m2 or more and 25 g/m2 or less. Herein, the basic weight of the nonwoven fabric 10 as a whole is measured according to the (Measuring method of basic weight of fibre mass layer 8 and non-fibre mass layer 9) mentioned above.
With regard to such a nonwoven fabric 10, when a thickness of the nonwoven fabric 10, measured under a pressure of 7.64 kPa in a position in which the fibre mass portion 7 is arranged, is taken as Ti, and a thickness of the nonwoven fabric 10, measured under the same pressure in a position in which the fibre mass portion 7 is not arranged, is taken as 12, as a difference 13 of thickness defined by an equation: T3 = Ti -T2 is smaller, the hardness caused by the fibre mass portion 7 becomes harder to be sensed. As a result, the cushion feeling accompanied by the bulkiness caused by lamination of a plurality of fibre layers is easily felt, and the soft texture is easily sensed. From this viewpoint, the difference of thickness T3 is preferably 0.4 mm or less, more preferably 0.3 mm or less, further preferably 0.2 mm or less, and most preferably 0 (zero) mm.
The expression "the position in which the fibre mass portion is arranged" herein means the position in which presence of the fibre mass portion 7 can be visually confirmed on the surface in the plane view upon the plane view from a surface on a pressure application side between top and back surfaces of the nonwoven fabric 10 (hereinafter, the expression has the same meaning herein). The expression "the position in which the fibre mass portion is not arranged" means the position in which presence of the fibre mass portion 7 is unable to be visually confirmed on the surface in the plane view described above (hereinafter, the expression has the same meaning herein).
(Method of measuring thickness of nonwoven fabric under 7.64 kPa pressure) A mechanical dial gauge type thickness gauge (JIS B7503 (1997), UPRIGHT DIAL GAUGE, manufactured by PEACOCK, under a pressure of 7.64 kPa, a tip of a gauge head: cp5 mm flat type disk) is used, whereby the thickness Ti in the position in which the fibre mass portion in the nonwoven fabric is arranged is measured, and the thickness T2 in the position in which the fibre mass portion in the nonwoven fabric is not arranged is measured to determine the difference of thickness defined by the equation: T3 = Ti -T2. Measurement is performed on five points or more for each of Ti and 12. Then, an average value of Ti and an average value of T2 are calculated, and a difference therebetween is taken as T3. In addition, a load of 7.64 kPa is a measurement condition set to clarify presence of the fibre mass portion.
The soft texture of the nonwoven fabric 10 is expressed in terms of a value of an average friction coefficient, and a smaller value means that the nonwoven fabric 10 is superior in the texture. In general, the value of the average friction coefficient becomes smaller in a part in which the fibre mass portion 7 is not arranged than in a part in which the fibre mass portion 7 is arranged. However, in the nonwoven fabric 10 of this embodiment, a plurality of fibre layers is laminated in the thickness direction and integrated, whereby the average friction coefficient is reduced in the position in which the fibre mass portion 7 is arranged. From a viewpoint of retaining the soft texture, an average friction coefficient (01) in the position in which the fibre mass portion 7 of the nonwoven fabric 10 is arranged is preferably 2.5 or less, more preferably 2.4 or less, and further preferably 2.3 or less, and practically 1.6 or more. Specifically, the average friction coefficient (01) in the position in which the fibre mass portion 7 of the nonwoven fabric 10 is arranged is preferably 1.6 or more and 2.5 or less, more preferably 1.6 or more and 2.4 or less, and further preferably 1.6 or more and 2.3 or less.
From a viewpoint of retaining the soft texture, a difference 03 (= 01 -Q2) between the average friction coefficient Olin the position in which the fibre mass portion 7 of the nonwoven fabric 10 is arranged and an average friction coefficient 02 in the position in which the fibre mass portion 7 of the nonwoven fabric 10 is not arranged is preferably 0.7 or less, more preferably 0.5 or less, further preferably 0.32 or less, particularly preferably 0.3 or less, and most preferably 0 (zero).
(Method of measuring average friction coefficient) The nonwoven fabric to be measured is cut into a 15 cm square to measure MIU values, on a measurement surface, in a position in which the fibre mass portion is arranged and a position in which the fibre mass portion is not arranged, under conditions of SENS: 2 x 5, and a load of 4.9 kPa, by using KESFB4 Surface Tester, manufactured by Kato Tech Co., Ltd. Measurement is performed on five points or more for each in two directions perpendicular to each other (typically, an MD direction and a CD direction), and average values thereof are taken as the MIU values. The MIU value is a value of the average friction coefficient, and a larger value is evaluated that the surface is rougher and the feeling is poorer, and a smaller value is evaluated that the surface is smoother and the feeling is better.
The fibre mass layer 8 mentioned above is preferably an outermost layer of the nonwoven fabric 10. In this case, the fibre mass layer 8 may be in the case where the fibre mass layer 8 is present only on one surface of the top and back surfaces of the nonwoven fabric 10, or in the case where the fibre mass layer 8 is present on the surfaces of both the top and back surfaces of the nonwoven fabric 10. The fibre mass layer 8 is the layer on the outermost layer of the nonwoven fabric 10, whereby a visual effect is maximised.
From a viewpoint of retaining the soft texture of the nonwoven fabric 10, the number of fibre mass portions 7 arranged in the nonwoven fabric 10 is preferably 50 or less, more preferably 40 or less, and further preferably 30 or less in terms of an average for each region of 10 cm square in the plane view of the top and back surfaces of the nonwoven fabric 10 (plane view in a state in which respective fibre layers are laminated). On the other hand, from a viewpoint of providing the pattern, the number of fibre mass portions 7 arranged in the nonwoven fabric 10 is preferably 5 or more, more preferably 10 or more, and further preferably 20 or more in terms of the average for each region of 10 cm square in the plane view of the top and back surfaces of the nonwoven fabric 10 (plane view in the state in which the respective fibre layers are laminated). Specifically, the number of fibre mass portions 7 is preferably 5 or more and 50 or less, more preferably 10 or more and 40 or less, and further preferably 20 or more and 30 or less, in terms of an average for each region of 10 cm square in the plane view of the top and back surfaces of the nonwoven fabric 10 (plane view in a state in which respective fibre layers are laminated).
From a viewpoint of reducing an opportunity of contact between skin and the fibre mass portion 7, between the fibre layers laminated, the number of fibre mass portions 7 in the fibre layer serving as the skin surface side of the absorbent article is preferably 30 or less, more preferably 20 or less, and further preferably 10 or less in terms of an average for each region of 10 cm square in the plane view of the fibre layer serving as the skin surface side. The number of fibre mass portions 7 in the fibre layer serving as the skin surface side of the absorbent article is preferably 1 or more. Specifically, the number of fibre mass portions 7 in the fibre layer serving as the skin surface side of the absorbent article is preferably 1 or more and 30 or less, more preferably 1 or more and 20 or less, and further preferably 1 or more and 10 or less, in terms of an average for each region of 10 cm square in the plane view of the fibre layer serving as the skin surface side.
From a viewpoint of forming the deep pattern, between two layers laminated, the number of fibre mass portions 7 arranged in the fibre layer serving as the non-skin surface side of the absorbent article is preferably 3 or more, more preferably 8 or more, and further preferably 15 or more in terms of an average for each region of 10 cm square in the plane view of the fibre layer serving as the non-skin surface side.
From a viewpoint of retaining the soft texture of the nonwoven fabric 10, a size (area) of an individual fibre mass portion 7 in the plane view of the nonwoven fabric 10 is preferably 10 mm2 or less, more preferably 8 mm2 or less, and further preferably 6 mm2 or less. On the other hand, from a viewpoint of providing the pattern, the size of an individual fibre mass portion 7 in the plane view of the nonwoven fabric 10 is preferably 1 mm2 or more, more preferably 2.5 mm2 or more, and further preferably 4 mm2 or more. Specifically, the size (area) of an individual fibre mass portion 7 in the plane view of the nonwoven fabric 10 is preferably 1 mm2 or more and 10 mm2 or less, more preferably 2.5 mm2 or more and 8 mm2 or less, and further preferably 4 mm2 or more and 6 mm2 or less.
The size of the fibre mass portion 7 arranged in the fibre layer serving as the skin surface side of the absorbent article in the plane view of the nonwoven fabric 10 is preferably 9 mm2 or less, more preferably 7 mm2 or less, and further preferably 5 mm2 or less.
From a viewpoint of forming the deep pattern, between the two layers laminated, the size of the fibre mass portion 7 arranged in the fibre layer serving as the non-skin surface side of the absorbent article in the plane view of the nonwoven fabric 10 is preferably 2 mm2 or more, more preferably 3 mm2 or more, and further preferably 5 mm2 or more.
From a viewpoint of retaining the soft texture of the nonwoven fabric 10, a size (thickness) of the individual fibre mass portion 7 in the thickness direction of the nonwoven fabric 10 is preferably 50% or less, more preferably 40% or less, and further preferably 30% or less in terms of a proportion to the thickness of the nonwoven fabric 10. On the other hand, from a viewpoint of the feeling, the size (thickness) of the individual fibre mass portion 7 in the thickness direction of the nonwoven fabric 10 is preferably as small as possible in the range of the size of more than 0% in terms of the proportion to the thickness of the nonwoven fabric 10. Specifically, the size (thickness) of the individual fibre mass portion 7 in the thickness direction of the nonwoven fabric 10 is preferably more than 0% and 50% or less, more preferably more than 0% and 40% or less, and further preferably more than 0% and 30% or less, in terms of a proportion to the thickness of the nonwoven fabric 10.
From a viewpoint of relaxing the hardness felt upon contact of skin with the fibre mass portion 7 by a plurality of fibre layers laminated and integrated, between the two layers laminated, the size of the fibre mass portion 7 arranged in the fibre layer serving as the skin surface side of the absorbent article in the thickness direction of the nonwoven fabric 10 is preferably 50% or less, more preferably 40% or less, and further preferably 30% or less in terms of the proportion to the thickness of the nonwoven fabric 10.
From the same viewpoint as described above, the size (thickness) of the individual fibre mass portion 7 in the thickness direction of the nonwoven fabric 10 is preferably 1 mm or less, more preferably 0.8 mm or less, and further preferably 0.5 mm or less, and is preferably as small as possible in the range of the size of more than 0 mm. Specifically, the size (thickness) of the individual fibre mass portion 7 in the thickness direction of the nonwoven fabric 10 is preferably more than 0 mm and 1 mm or less, more preferably more than 0 mm and 0.8 mm or less, and further preferably more than 0 mm and 0.5 mm or less.
{0048} (Method of measuring the number of fibre mass portions, area and thickness) From an observation target surface of a nonwoven fabric cut into a 10 cm square (for example, a surface 10A in the nonwoven fabric 10), a photograph is taken by using Microscope (VHX-900, manufactured by Keyence Corporation).
Data of this photograph (jpeg) is subjected to image analysis processing by using image analysis software (NexusNewQube). Binarisation processing is performed to determine the number and area of the fibre mass portions. Moreover, all the mass portions are cut in the thickness direction by using the razor edge, and cross sections are observed by using the Microscope described above to measure a thickness of the nonwoven fabric and a thickness of the fibre mass portion. {0049} The air-through nonwoven fabric for an absorbent article according to the present invention is used as a constituent component of an absorbent article. Examples of the absorbent article include various articles provided with a function of absorbing and retaining a human excretory fluid, such as nappies, sanitary towels, urine pads and panty liners.
The air-through nonwoven fabric for an absorbent article according to the present invention is used as various members of the absorbent article according to its function, and is incorporated into the absorbent article. For example, when the air-through nonwoven fabric has liquid permeability, the air-through nonwoven fabric is incorporated thereinto as a topsheet, and when the air-through nonwoven fabric has water repellency, the air-through nonwoven fabric is incorporated thereinto as a side sheet. The air-through nonwoven fabric is processed into a thinner and softer material, and is incorporated thereinto as an exterior material for improving the texture on an outside (clothing side) of the absorbent article such as nappies.
Among them, from viewpoints of facilitating to sense the feeling of the nonwoven fabric excellent in the bulkiness and the soft texture with skin, and facilitating to visually recognise the pattern of the nonwoven fabric, it is preferable that the air-through nonwoven fabric for an absorbent article according to the present invention is arranged in the outermost layer on the skin surface side of the absorbent article, and the fibre mass layer 8 is arranged toward the skin surface side. Example thereof include a topsheet and a side sheet, and it is particularly preferable that the air-through nonwoven fabric for an absorbent article according to the present invention is arranged in the absorbent article as the topsheet Next, a preferred embodiment of the method of producing the air-through nonwoven fabric for an absorbent article according to the present invention will be described. Here, the embodiment is described as the method of producing the nonwoven fabric 10 according to the embodiment mentioned above. However, the fibre layers to be laminated are not limited to two layers (the fibre layer 1 and the fibre layer 2), and may be layers formed by laminating three or more fibre layers.
{0051} The producing method of this embodiment contains the following step 501 and step 502.
Step 501: An opening step in which a plurality of times of opening treatment are applied to thermoplastic fibres to form a web.
Step 502: A step in which a plurality of single-layer webs obtained in the opening step are laminated to form a laminated web, and air-through processing by hot air is applied to the laminated web to obtain an air-through nonwoven fabric.
In addition, the producing method of this embodiment contains the following step 503.
Step 503: A calendering step in which calendering is applied to one or more of sheets selected from the single-layer web, the laminated web and the air-through nonwoven fabric by using a pair of calender rolls.
The step 503 is performed in any one or more of places selected from after the step 501 and before the step 502; on the way of the step 502; and after the step 502.
FIG. 2 shows a production apparatus 100 preferably used in the method of producing the nonwoven fabric 10 of this embodiment. The production apparatus 100 has, from an upstream side to a downstream side, opening units 101 and 102 for fibre materials serving as raw materials of the nonwoven fabric, carding units 103 and 104 for forming fibre webs, a laminated web-forming unit 105 for conveying the single-layer webs carded and thus obtained to laminate the single web layers, a web calendering unit 106 for performing pressure application treatment to the laminated web, and a heat treatment unit (air-through processing unit) 107.
In the production apparatus 100, the step 501 described above is performed in the opening units 101 and 102, and the carding units 103 and 104. The step 502 described above is performed in the laminated web-forming unit 105 and the heat treatment unit 107.
In the production apparatus 100, the step 503 described above is performed in the web calendering unit 106. The web calendering unit 106 is arranged between the laminated web-forming unit 105 and the heat treatment unit 107, and the step 503 described above is performed as the web calendering for the laminated web on the way of the step 502 described above.
{0054} Each of the opening units 101 and 102 has a device for opening the thermoplastic fibres serving as the raw materials of the fibre layers 1 and 2 to feed the resulting material to each of the next carding units 103 and 104. When the fine fibres and the thick fibres each having the specific fibre diameter mentioned above are used, opening is preferably performed in a divided manner between the fine fibres and the thick fibres. FIG. 2 shows that raw material fibres (fine fibres) 71 are charged into the opening unit 101 and opened (arrow 171), and raw material fibres (thick fibres) 72 are charged into the opening unit 102 and opened (arrow 172) As the raw material fibres (fine fibres) 71 and the raw material fibres (thick fibres) 72, various thermoplastic fibres used for the air-through nonwoven fabric can be used. Examples thereof include conjugate fibres having a core-sheath structure, in which a melting point is lower in a resin component of the sheath than in a resin component of the core.
In the carding units 103 and 104, the fibres opened in each of the opening units 101 and 102 are received (arrows 173 and 174) to form single-layer webs 81 and 82. Specifically, an aggregate of the fibres opened in the opening units 101 and 102 is combed, and the resulting fibres are further opened to form a sheet-like web. In the carding unit 103, the single-layer web 81 based on the raw material fibres (fine fibres) 71 is formed, and in the carding unit 104, the single-layer web 82 based on the raw material fibres (thick fibres) 72 is formed.
In the carding units 103 and 104, various carding machines ordinarily used for producing the air-through nonwoven fabric can be used without particular limitation. Examples thereof include a parallel carding machine, a semi-random carding machine, a random carding machine and a machine in which a cross layer and a drafter are combined with the parallel carding machine. Moreover, examples of the carding machine include a machine equipped with three kinds of rolls; namely, a main cylinder roll covered with a sawtooth-shaped metallic wire, a worker roll, and a stripper roll. The aggregate of fibres is combed between the main cylinder roll, and the worker roll and the stripper roll, whereby opening can be performed. A plurality of sets of worker rolls and stripper rolls is arranged on the main cylinder roll, whereby a plurality of times of opening treatment can be performed in each carding machine in the carding units 103 and As described above, a plurality of times of opening treatment is to be performed in both the opening units 101 and 102 and the carding units 103 and 104.
In the producing method of this embodiment, the opening step (step 501) in which a plurality of times of opening treatment is applied to the thermoplastic fibres to form the web in the opening units 101 and 102 and the carding units 103 and 104 is performed.
Next, in the laminated web-forming unit 105, the single-layer web 82 formed in the carding unit 104 is laminated on the single-layer web 81 formed in the carding unit 103 to form a laminated web 90.
Specifically, the single-layer web 81 is carried out from the carding unit 103 along a carrying out belt 103A, and placed on a conveyor belt 105A. The conveyor belt 105A conveys the single-layer web 81 to a downstream. The single-layer web 82 is carried out from the carding unit 104 along the carrying out belt 104A, and guided to the conveyor belt 105A and laminated on the single-layer web 81 during being conveyed. Thus, the formed laminated web 90 is conveyed further to the downstream along the conveyor belt 105A. In the laminated web 90, parts corresponding to the single-layer webs 81 and 82 are referred to simply as webs 81 and 82.
In the laminated web 90, the web 82 is formed of the raw material fibres (thick fibres) 72, and the web 81 is formed of the raw material fibres (fine fibres) 71. Therefore, an average fibre diameter of the web 82 is adjusted to be larger than an average fibre diameter of the web 81. From this configuration, the web 81 is formed into the fibre mass layer 8 including the fine fibres having the specific fibre diameter described above in the completed nonwoven fabric 10. The web 82 can be applied as the non-fibre mass layer 9 including the thick fibres having the specific fibre diameter described above in the completed nonwoven fabric 10. An increase of a basis weight in the non-fibre mass layer 9 than in the fibre mass layer 8 in the completed nonwoven fabric 10 can be realised by increasing feed mass of the fibres from the opening unit 102 to the carding unit 104 than feed mass of the fibres from the opening unit 101 to the carding unit 103. {0062} Thus, in the producing method of this embodiment, it is preferable to use a plurality of kinds of fibres having different fibre diameters to form the laminated web. In particular, it is more preferable to differentiate the fibre diameters between the web 82 and the web 81.
In the fibres having different fibre diameters, it is preferable that fine fibres having a fibre diameter of 1 dtex or more and 2.2 dtex or less are used.
Moreover, it is more preferable that the fibre diameter of the fine fibres is in the range of the fibre diameter mentioned above.
In the web calendering unit 106, the web calendering for interposing the conveyed laminated web 90 between a pair of calendering rolls 106A and 106B is performed to apply pressure to the laminated web 90 (hereinafter, referred to simply as "calendering" in several cases). Thus, a web surface in a part in which the fibre mass portion 7 is present can be smoothened to reduce the hardness of the fibre mass portion 7.
{0064} In particular, in the producing method of this embodiment, the calendering is performed on the laminated web 90 before being formed into the nonwoven fabric, and therefore places between the fibres are not fused and fixed yet, and the fibres can be significantly moved. That is, in the calendering of this embodiment, there is no risk of causing peeling, fracture or the like of the fibres in a fused part between the fibres, and the fibres collected in the fibre mass portion 7 can be preferably discretized (intervals between the fibres are extended) while keeping a good fibre state, and the fibre mass portion 7 can be satisfactorily flattened. Thus, a hardness reduction effect of the fibre mass portion 7 is increased. In pressure application in the thickness direction by the calendering, the fibres with each other in the fibre mass portion 7 are easily discretized in both the laminated webs 81 and 82 before being formed into the nonwoven fabric, and the hardness reduction effect of the fibre mass portion 7 is increased in the laminated web 90 as a whole (hereinafter, the laminated web subjected to the web calendering is referred to as a laminated web 95 in several cases). In a series of production steps, the air-through processing mentioned later is performed after performing the calendering described above, whereby the air-through processing can be utilised as recovery processing of the nonwoven fabric thickness. That is, in this embodiment, the processing steps performed in this order are significant in recovering the thickness of the laminated web 95 into a material further bulky and superior in the soft texture, and in forming the pattern. {0065} In the heat treatment unit 107, the air-through processing by hot air is applied to the laminated web 95 subjected to the web calendering.
Specifically, the heat treatment unit 107 has a hood 107A and a conveyor belt 107B equipped with an air-permeable net and circulating in the hood 107A.
In the hood 107A, hot air is configured to be blown toward the conveyor belt 107B from above (arrow F shown in FIG. 2). In the conveyor belt 107B, hot air blown is configured to be blown through by the air-permeable net described above. The laminated web 95 subjected to the web calendering is pushed out to the heat treatment unit 107 by roll rotation in the web calendering unit 106. In the heat treatment unit 107, the laminated web 95 is conveyed into the hood 107A by the conveyor belt 107B. Hot air heated to a predetermined temperature is blown to the laminated web 95 in the hood 107A from above the laminated web 95 (namely, above the web 82) in the thickness direction by the pass-through method. That is, the air-through processing is applied to the laminated web 95.
Thus, in the laminated web 95, the intervals between the fibres in the fibre mass portion 7 are extended by the web calendering mentioned above, and the intersections of the fibres with each other are fused by blowing of hot air while keeping a fibre state in which the hardness of the fibre mass portion 7 is relaxed.
Thus, the air-through nonwoven fabric 10 for an absorbent article of this embodiment is obtained.
As described above, in the producing method of this embodiment, the step 502 described above and the step 503 described above are performed on the single-layer webs 81 and 82 obtained through the opening step in the step 501 described above by the laminated web-forming unit 105, the web calendering unit 106 and the heat treatment unit 107. Specifically, the step 502 by the laminated web-forming unit 105 and the heat treatment unit 107, and the calendering step (step 503) by the web calendering unit 106 on the way thereof are performed.
These steps 501, 502 and 503 are performed, whereby the air-through nonwoven fabric 10 for an absorbent article of this embodiment mentioned above can be produced to a high degree of perfection. That is, even if the air-through nonwoven fabric 10 contains the fibre layer 8 containing the fibre mass portion 7, the air-through nonwoven fabric 10 for an absorbent article, having excellent bulkiness and soft texture, and having the pattern can be produced to a high degree of perfection. The produced air-through nonwoven fabric 10 for an absorbent article is wound in a roll shape, when necessary.
In the producing method of this embodiment, the calendering step (step 503) is performed on the laminated web 90 before being subjected to the air-through processing. However, the calendering step is not limited thereto, and the calendering may be individually performed on the single-layer web 81 and the single-layer web 82 before lamination, or the calendering may be performed on the air-through nonwoven fabric after the air-through processing. When the calendering is performed on the air-through nonwoven fabric, the air-through nonwoven fabric to be processed serves as a raw material air-through nonwoven fabric before being formed into the air-through nonwoven fabric 10 for an absorbent article of this embodiment.
In the producing method of this embodiment, the calendering step (step 503) is performed, whereby the fibre mass portion 7 is flattened by the calender, and a part other than the fibre mass portion 7 is also smoothened by calendering to be smooth. In the nonwoven fabric 10 the surface of which becomes smooth, the thicknesses of a plurality of fibre layers are retained into an integrated material, and therefore the resulting material is formed into a product provided with a thickness at a degree of reducing a foreign matter feeling (uncomfortable feeling) in contact with skin for the fibre mass portion 7, and the cushioning properties.
In the producing method of this embodiment, the fibre mass can be flattened in an integrated nonwoven fabric production step. Therefore, a necessity of introducing a fibre mass inspection device after producing the nonwoven fabric is eliminated, whereby a production cost can be reduced. A necessity of inspection treatment after production, posterior calendering treatment and hot air recovery treatment is eliminated, and therefore improvement in production efficiency of the nonwoven fabric can be realised.
From a viewpoint of effectively reducing the hardness of the fibre mass portion 7, the calendering described above is preferably the web calendering performed on one or more of sheets selected from the single-layer web or the laminated web.
The calendering is not limited to the case where the calendering is performed only in one stage among a single-layer web stage, a laminated web stage and an air-through nonwoven fabric stage, and may be performed in two or more stages. The calendering is not limited to the case where the calendering is performed once in each stage, and may be performed two or more times. For example, the calendering is not limited to the case where the calendering on the laminated web 90 of this embodiment is performed only once, and may be performed two or more times.
{0071} A linear pressure in the calendering step, namely, the linear pressure applied to the laminated web 90, the single-layer webs 81 and 82, and the air-through nonwoven fabric (raw material air-through nonwoven fabric) compressed between the calender rolls 106A and 106B is preferably the highest among the linear pressures applied to the single-layer webs 81 and 82, the laminated webs and 95 and the air-through nonwoven fabric 601 by all the rolls in all the steps. The term "all the rolls" herein means all the rolls used in the whole production steps in addition to the calender rolls 106A and 106B mentioned above. For example, a nip roll for conveying the nonwoven fabric after heat treatment, a nip roll or a press roll during winding, a press roll during slitting after winding, and the like fall under the term.
In particular, in the calendering step, from a viewpoint of effectively reducing the hardness of the fibre mass portion 7 before performing thermal fusion, a linear pressure (P) applied to the single-layer webs 81 and 82 and the laminated web 90 is preferably 20 N/cm or more, more preferably 100 N/cm or more, and further preferably 180 N/cm or more. Moreover, from a viewpoint of recoverability of thickness after pressure application, the linear pressure (P) described above is preferably 700 N/cm or less, more preferably 500 N/cm or less, and further preferably 250 N/cm or less. Specifically, the linear pressure (P) is preferably 20 N/cm or more and 700 N/cm or less, more preferably 100 N/cm or more and 500 N/cm or less, and further preferably 180 N/cm or more and 250 N/cm or less.
A pair of calender rolls 106A and 106B used in the web calendering unit 106 are rolls peripheral surface of which are smooth. As a material thereof, various materials used for the calendering can be used. Moreover, a material of the calender roll 106A and a material of the calender roll 106B may be identical to or different from each other.
Among them, from a viewpoint of further enhancing an effect of reducing the hardness of the fibre mass portion 7, the calender roll used for the calendering is preferably a combination of a resin roll and a steel roll. In the web calendering of this embodiment, as the calender roll 106A, the steel roll is used as the roll in contact with the web 82 containing the thick fibres of the laminated web 90, and as the calender roll 106B, the resin roll is used as the roll in contact with the web 81 containing the fine fibres of the laminated web 90. However, arrangement of the resin roll and the steel roll is not limited thereto, and may be a reverse combination.
From a viewpoint of further enhancing the effect of reducing the hardness of the fibre mass portion 7, the hardness of the resin roll described above is preferably 20 degrees or more, more preferably 50 degrees or more, and further preferably 80 degrees or more in D hardness (JIS K 6253-3). From the same viewpoint as described above, the hardness of the resin roll is preferably 100 degrees or less, more preferably 95 degrees or less, and further preferably 90 degrees or less in D hardness (JIS K 6253-3). Specifically, the hardness of the resin roll described above is preferably 20 degrees or more and 100 degrees or less, more preferably 50 degrees or more and 95 degrees or less, and further preferably 80 degrees or more and 90 degrees or less.
The air-through processing preferably has a plurality of air-through treatment.
FIG. 3 shows an aspect of a heat treatment unit (air-through processing unit) having a first air-through treatment unit 117 and a second air-through treatment unit 127. In this aspect, the air-through processing is performed twice by the first air-through treatment and the second air-through treatment. However, the number of times of the air-through treatment is not limited to two times in FIG. 3, and may be three or more times. When the air-through processing has three or more times of the air-through treatment, the expression "latter stage air-through treatment" to "initial air-through treatment" means the air-through treatment in and after second time air-through treatment. In two times of the air- through treatment in FIG. 3, the "initial air-through treatment" means the first air-through treatment, and the "latter stage air-through treatment" means the second air-through treatment. In the air-through step (two times of the air-through treatment) shown in FIG. 3, hot air is blown in the hood 107C in the first air-through treatment unit 117 (arrow F1), and hot air is blown in the hood 107D in the second air-through treatment unit 127 (arrow F2). At this time, the laminated web 95 subjected to the web calendering is continuously conveyed from the first air-through treatment unit 117 to the second air-through treatment unit 127 by the conveyor belt 107B. Thus, the first air-through treatment and the second air-through treatment are continuously applied to the laminated web 95.
In the air-through step described above, it is preferable that a speed of hot air in the latter stage air-through treatment is faster than a speed of hot air in the initial air-through treatment, that is, the initial air-through treatment is performed at a lower air speed. Thus, bulkiness reduction by an air pressure in the air-through treatment unit is suppressed, and a recovery effect by hot air is exhibited, resulting in high bulkiness of the web. In particular, when the calendering is performed on the laminated web 90 or the single-layer webs 81 and 82 before being formed into the nonwoven fabric as described in this embodiment, the treatment described above in the subsequent air-through treatment is effective.
Specifically, the speed Si of hot air in the initial air-through treatment is preferably 0.2 m/sec or more, more preferably 0.25 m/sec or more, and further preferably 0.4 m/sec or more. The speed 51 of hot air in the initial air-through treatment is preferably 1.2 m/sec or less, more preferably 0.8 m/sec or less, and further preferably 0.5 m/sec or less. Specifically, the air speed Si is preferably 0.2 m/sec or more and 1.2 m/sec or less, more preferably 0.25 m/sec or more and 0.8 m/sec or less, and further preferably 0.4 m/sec or more and 0.5 m/sec or less. Thus, flattening of the web is suppressed, and the recovery effect of the thickness is exhibited.
The speed 52 of hot air in the latter stage air-through treatment is preferably 0.8 m/sec or more, more preferably 0.9 m/sec or more, and further preferably 1.2 m/sec or less. The speed S2 of hot air in the latter stage air-through treatment is preferably 1.6 m/sec or less, more preferably 1.4 m/sec or less, and further preferably 1.3 m/sec or less. Specifically, the air speed S2 is preferably 0.8 m/sec or more and 1.6 m/sec or less, more preferably 0.9 m/sec or more and 1.4 m/sec or less, and further preferably 1.2 m/sec or more and 1.3 m/sec or less. Thus, air uniformly passes through the web, and thermal energy is effectively provided thereto into a nonwoven fabric structure.
The difference S3 (= S2 -Si) between the speed 51 of hot air in the initial air-through treatment and the speed S2 of hot air in the latter stage air-through treatment is preferably more than 0 m/sec, more preferably 0.4 m/sec or more, and further preferably 0.8 m/sec or more. The difference S3 (= 52 -Si) between the speed Si of hot air in the initial air-through treatment and the speed S2 of hot air in the latter stage air-through treatment is preferably 1.4 m/sec or less, more preferably 1.2 m/sec or less, and further preferably 1 m/sec or less. Specifically, the difference S3 (= S2 -Si) between the speed Si of hot air in the initial air-through treatment and the speed S2 of hot air in the latter stage air-through treatment is preferably more than 0 m/sec and 1.4 m/sec or less, more preferably 0.4 m/sec or more and 1.2 m/sec or less, and further preferably 0.8 m/sec or more and 1 m/sec or less. Thus, satisfaction of both bulkiness recovery and formation of the nonwoven fabric can be effectively realised.
{0080} In the air-through step described above, a temperature of hot air in the latter stage air-through treatment is preferably higher than in the initial air-through treatment. Thus, fusion of the fibres progresses stepwise to effectively develop recovery of the web in the air-through treatment unit. In particular, when the calendering is performed on the laminated web 90 or the single-layer webs Si and 82 before being formed into the nonwoven fabric as described in this embodiment, the effect described above in the subsequent air-through treatment is higher.
Specifically, the temperature P1 of hot air in the initial air-through treatment is preferably 85°C or more, more preferably 90°C or more, and further preferably 100°C or more. The temperature P1 of hot air in the initial air-through treatment is preferably 134°C or less, more preferably 115°C or less, and further preferably 105°C or less. Specifically, the temperature P1 of hot air in the initial air-through treatment is preferably 85°C or more and 134°C or less, more preferably 90°C or more and 115°C or less, and further preferably 100°C or more and 105°C or less. Thus, recoverability of the web in the air-through treatment unit can be effectively exhibited.
The temperature P2 of hot air in the latter stage air-through treatment is equal to or more than a melting point of the component on a surface of the fibres to be used (for example, a sheath portion in core-sheath type conjugate fibres), and is preferably 145°C or less, more preferably 137°C or less, and further preferably 134°C. Specifically, the temperature P2 of hot air in the latter stage air-through treatment is preferably equal to or more than a melting point of the component on a surface of the fibres to be used and 145°C or less, more preferably equal to or more than a melting point of the component on a surface of the fibres to be used and 137°C or less, and further preferably equal to or more than a melting point of the component on a surface of the fibres to be used and 134°C or less. Thus, production of the nonwoven fabric having the texture with the good feeling can be realised.
The difference P3 (= P2 -P1) between the temperature P1 of hot air in the initial air-through treatment and the temperature P2 of hot air in the latter stage air-through treatment is preferably more than 0°C, more preferably 20°C or more, and further preferably 30°C or more. The difference P3 (= P2 -P1) between the temperature P1 of hot air in the initial air-through treatment and the temperature P2 of hot air in the latter stage air-through treatment is preferably 60°C or less, more preferably 40°C or less, and further preferably 35°C or less. Specifically, the difference P3 (= P2 -P1) between the temperature P1 of hot air in the initial air-through treatment and the temperature P2 of hot air in the latter stage air-through treatment is preferably more than 0°C and 60°C or less, more preferably 20°C or more and 40°C or less, and further preferably 30°C or more and 35°C or less. Thus, production of a bulky nonwoven fabric having the good feeling can be realised.
{0084} In the method of producing the air-through nonwoven fabric for an absorbent article of this embodiment, as described below, it is preferable that unnecessary parts such as patches generated in the production steps are once collected and returned to the opening step again (step 504).
In this step 504, the method has one or both of a step of collecting crosswise end portions of the web in the carding machine used in the opening step described above, and a step of partly collecting the air-through nonwoven fabric described above, and cutting and opening a part of the collected air-through nonwoven fabric. The collected web described above and the cut and opened part of the air-through nonwoven fabric are provided for the opening step described above. The term "the cut and opened part of the air-through nonwoven fabric" means the part including patch parts of the crosswise end portions, and without being limited thereto, a product during adjusting processing conditions or an out-of-specification product generated in the step of producing the nonwoven fabric.
FIG. 2 shows a specific example of the step 504 described above. The crosswise end portions (not shown) are sucked and collected for the single-layer webs 81 and 82 formed in the carding machine of the carding units 103 and 104 (arrows 181 and 182). The air-through nonwoven fabric 10 obtained by performing the air-through processing in the heat treatment unit 107 is partly collected (arrow 183). In this case, the part of the collected air-through nonwoven fabric is unable to be reused as it is, and therefore the part is cut and opened in a cutting and opening unit 108 to be returned into a fibrous form.
The collected web and the cut and opened part of the air-through nonwoven fabric are returned to the opening unit 101, and opened again, and used as a material for forming the web (arrow 184). At this time, the material can be returned to either the opening unit 101 or the opening unit 102 or both thereof.
FIG 2 shows a process in which the material is to be returned to the opening unit 101. When the material is returned to the opening unit 101, it is preferable to appropriately adjust an amount of charging new raw material fibres (fine fibres) 71 so that a proportion of the fine fibres in the web 81 to be formed may be maintained at a constant level or more, and a content of the thick fibres is suppressed within several percentages (for example, within 5%). Thus, while the fibre mass portion 7 is formed in the web 81, the nonwoven fabric 10 contains a large amount of fine fibres, and the soft texture on a side of the surface 10A of the nonwoven fabric 10 can be realised.
Return of the material described above is not limited to the aspect in FIG. 2. For example, the return may be in an aspect in which a material collected from the carding unit 103 is returned to the opening unit 101, and a material collected from the carding unit 104 is returned to the opening unit 102. On the occasion, it is preferable to return the cut and opened part of the air-through nonwoven fabric to the opening unit 102.
As described above, according to the producing method of this embodiment, the nonwoven fabric 10 excellent in the bulkiness and the soft texture, and having the pattern can be preferably produced. In particular, the nonwoven fabric 10 provided with physical properties indicated by the thicknesses Ti and T2 and the difference 13 (= Ti -T2) under the pressure of 7.64 kPa described above, and the average friction coefficients 01 and Q2 and the difference Q3 (= 01 -02) can be preferably produced. The nonwoven fabric 10 is provided with the aesthetics caused by the pattern formed by the fibre mass portion 7, particularly the pattern formed by the fibre mass portion 7 in which the thickness thereof is reduced.
The thus obtained air-through nonwoven fabric for an absorbent article according to the present invention is incorporated thereinto as a predetermined component in an absorbent article according to a purpose (incorporation step) in the production step of an absorbent article. The incorporation step is preferably the step as described below, for example. That is, the thus obtained air-through nonwoven fabric for an absorbent article according to the present invention is cut into a size or a shape or the like according to the purpose to prepare an intended material, and the intended material is placed in a predetermined position relative to other components. Then, the resulting material is rotated and folded together with other members, when necessary, and the resulting material is joined and incorporated into the absorbent article. Thus, the objective absorbent article is produced through the step of incorporating the air-through nonwoven fabric for an absorbent article according to the present invention thereinto in the production step of the absorbent article.
Among them, because the air-through nonwoven fabric for an absorbent article according to the present invention realises satisfaction of both the bulkiness and the soft texture, and is provided with the pattern capable of visually appealing to a user, it is preferable that the incorporation step described above is the step of incorporating the fabric into an outermost layer member (for example, the topsheet or the side sheet) on the skin surface side of the absorbent article. In particular, it is preferable that the step is the step of incorporating the nonwoven fabric into the absorbent article as the topsheet in contact with skin and most catching customer's eyes. It is preferable that the air-through nonwoven fabric for an absorbent article according to the present invention is provided with a configuration in which the fibre layer containing the fibre mass portion is applied as the outermost layer of the nonwoven fabric. It is more preferable that the air-through nonwoven fabric for an absorbent article according to the present invention is arranged in the outermost layer on the skin surface side of the absorbent article, and the fibre layer containing the fibre mass portion described above is arranged toward the skin surface side of the absorbent article. {0088} With regard to the above-mentioned embodiments, the present invention further discloses the air-through nonwoven fabrics for an absorbent article, and 15 the methods of producing an air-through nonwoven fabric for an absorbent article described below. <1>
An air-through nonwoven fabric for an absorbent article, in which two or more fibre layers are laminated, containing at least one fibre layer containing thermoplastic fibres and a fibre mass portion. <2>
The air-through nonwoven fabric for an absorbent article described in the 25 above item <1>, wherein the air-through nonwoven fabric for an absorbent article has fine fibres having a fibre diameter of 1 dtex or more and 2.2 dtex or less, preferably 1 dtex or more and more preferably 1.2 dtex or more, and preferably 2 dtex or less and more preferably 1.5 dtex or less; and thick fibres having a fibre diameter larger than the fine fibres, and wherein the fibre layer containing the fibre mass portion includes the fine fibres. <3> The air-through nonwoven fabric for an absorbent article described in the above item <2>, wherein a content of the fine fibres in the fibre layer containing the fibre mass portion is preferably 50% by mass or more, more preferably 80% by mass or more, and further preferably 100% by mass. <4>
The air-through nonwoven fabric for an absorbent article described in any one of the above items <1> to <3>, which contains at least one fibre layer containing no fibre mass portion. <5>
The air-through nonwoven fabric for an absorbent article described in the above item <4>, wherein the air-through nonwoven fabric for an absorbent article has thick fibres having a fibre diameter of more than 2.2 dtex and 7 dtex or less, preferably more than 2.2 dtex and more preferably 4.4 dtex or more, and preferably 5.5 dtex or less and more preferably 5 dtex or less; and fine fibres having a fibre diameter smaller than the thick fibres, and wherein the fibre layer containing no fibre mass portion includes the thick fibres. <6> The air-through nonwoven fabric for an absorbent article described in the above item <5>, wherein a content of the thick fibres in the fibre layer containing no fibre mass portion is preferably 50% by mass or more, more preferably 80% by mass or more, and further preferably 100% by mass. <7>
The air-through nonwoven fabric for an absorbent article described in the above item <5> or <6>, wherein a content of the thick fibres in the fibre layer containing the fibre mass portion is preferably 50% by mass or less, more preferably 30% by mass or less, and further preferably 10% by mass or less. <8>
The air-through nonwoven fabric for an absorbent article described in any one of the above items <4> to <7>, wherein an average fibre diameter in the fibre layer containing no fibre mass portion is larger than an average fibre diameter in the fibre layer containing the fibre mass portion. <9>
The air-through nonwoven fabric for an absorbent article described in the above item <8>, wherein a difference between the average fibre diameter of the fibre layer containing no fibre mass portion and the average fibre diameter of the fibre layer containing the fibre mass portion is more than 0 dtex and 5.6 dtex or less, preferably 2.2 dtex or more and more preferably 3 dtex or more, and preferably 4 dtex or less and more preferably 3.5 dtex or less. <10>
The air-through nonwoven fabric for an absorbent article described in any one of the above items <4> to <9>, wherein a basis weight in the fibre layer containing no fibre mass portion is larger than a basis weight in the fibre layer containing the fibre mass portion. <11>
The air-through nonwoven fabric for an absorbent article described in the above item <10>, wherein a difference between the basis weight of the fibre layer containing no fibre mass portion and the basis weight of the fibre layer containing the fibre mass portion is more than 0 g/m2 and 20 g/m2 or less, preferably 3 g/m2 or more and more preferably 5 g/m2 or more, and preferably 15 g/m2 or less and more preferably 10 g/m2 or less. <12>
The air-through nonwoven fabric for an absorbent article described in any one of the above items <1> to <11>, wherein a basis weight of the air-through nonwoven fabric for an absorbent article as a whole is 15 g/m2 or more and 40 g/m2 or less, preferably 18 g/m2 or more and more preferably 20 /m2 or more, and preferably 30 g/m2 or less and more preferably 25 g/m2 or less. <13>
The air-through nonwoven fabric for an absorbent article described in any one of the above items <1> to <12>, wherein when a thickness of the air-through nonwoven fabric for an absorbent article, measured under a pressure of 7.64 kPa in a position in which the fibre mass portion is arranged, is taken as Ti, and a thickness of the air-through nonwoven fabric for an absorbent article, measured under the same pressure in a position in which the fibre mass portion is not arranged, is taken as T2, a difference 13 of thickness defined by an equation: T3 = Ti -T2 is 0.4 mm or less, preferably 0.3 mm or less, more preferably 0.2 mm or less, and further preferably 0 (zero) mm. <14>
The air-through nonwoven fabric for an absorbent article described in any one of the above items <1> to <13>, wherein an average friction coefficient in the position in which the fibre mass portion of the air-through nonwoven fabric for an absorbent article is arranged is 1.6 or more and 2.5 or less, preferably 1.6 or more, and preferably 2.4 or less and more preferably 2.3 or less. <15>
The air-through nonwoven fabric for an absorbent article described in the above item <14>, wherein a difference between the average friction coefficient in the position in which the fibre mass portion of the air-through nonwoven fabric for an absorbent article is arranged and the average friction coefficient in the position in which the fibre mass portion of the air-through nonwoven fabric for an absorbent article is not arranged is 0.7 or less, preferably 0.5 or more, more preferably 0.32 or less, further preferably 0.3 or more, and particularly preferably 0 (zero).
{0093} <16> The air-through nonwoven fabric for an absorbent article described in any one of the above items <1> to <15>, wherein the fibre mass portion is formed into a flattened shape in which the fibres are flattened in the thickness direction of the nonwoven fabric when observed from the cross section of the nonwoven fabric in the thickness direction, and a surface of the fibre mass portion on a side of a nonwoven fabric surface has a smooth structure. <17>
The air-through nonwoven fabric for an absorbent article described in any one of the above items <1> to <16>, wherein the fibre layer containing the fibre mass portion is an outermost layer of the air-through nonwoven fabric for an absorbent article. <18>
An absorbent article, containing the air-through nonwoven fabric for an absorbent article described in any one of the above items <1> to <17>. <19>
An absorbent article, wherein the air-through nonwoven fabric for an absorbent article described in the above item <17> is arranged in the outermost layer on the skin surface side of the absorbent article, and the fibre layer containing the fibre mass portion is arranged toward the skin surface side. <20> The absorbent article described in the above item <18> or <19>, containing the air-through nonwoven fabric for an absorbent article as a topsheet. {0095} <21> A method of producing an air-through nonwoven fabric for an absorbent article, containing.
an opening step in which a plurality of times of opening treatment are applied to thermoplastic fibres to form a web; a step in which a plurality of single-layer webs obtained in the opening step are laminated to form a laminated web, and air-through processing by hot air is applied to the laminated web to obtain an air-through nonwoven fabric; and a calendering step in which calendering is applied to one or more of sheets selected from the single-layer web, the laminated web and the air-through nonwoven fabric by using a pair of calender rolls. <22>
The method of producing an air-through nonwoven fabric for an absorbent article described in the above item <21>, wherein, in all steps of the method of producing the air-through nonwoven fabric for an absorbent article, a linear pressure in the calendering step is the highest among the linear pressures applied to the single-layer web, the laminated web and the air-through nonwoven fabric. <23>
The method of producing an air-through nonwoven fabric for an absorbent article described in the above item <21> or <22>, wherein the calendering step is a web calendering performed on one or more of sheets selected from the single-layer web and the laminated web. <24>
The method of producing an air-through nonwoven fabric for an absorbent article described in the above item <23>, wherein, in the web calendering step, a linear pressure applied to the single-layer web or the laminated web is 20 N/cm or more and 700 N/cm or less, preferably 100 N/cm or more and more preferably 180 N/cm or more, and preferably 500 N/cm or less and more preferably 250 N/cm or less. <25>
The method of producing an air-through nonwoven fabric for an absorbent article described in any one of the above items <21> to <24>, wherein the pair of calender rolls used for the calendering step is a combination of a resin roll and a steel roll. <26>
The method of producing an air-through nonwoven fabric for an absorbent article described in the above item <25>, wherein the hardness of the resin roll is 20 degrees or more and 100 degrees or less, preferably 50 degrees or more and more preferably 80 degrees or more, and preferably 95 degrees or less and more preferably 90 degrees or less, in D hardness. <27>
The method of producing an air-through nonwoven fabric for an absorbent article described in any one of the above items <21> to <26>, wherein the air-through processing has a plurality of air-through treatments, and wherein a speed of hot air in the latter stage air-through treatment is faster than a speed of hot air in the initial air-through treatment. <28>
The method of producing an air-through nonwoven fabric for an absorbent article described in the above item <27>, wherein the speed of hot air in the initial air-through treatment is 0.2 m/sec or more and 1.2 m/sec or less, preferably 0.25 m/sec or more and more preferably 0.4 m/sec or more, and preferably 0.8 m/sec or less and more preferably 0.5 m/sec or less. <29>
The method of producing an air-through nonwoven fabric for an absorbent article described in the above item <27> or <28>, wherein the speed of hot air in the latter stage air-through treatment is 0.8 m/sec or more and 1.6 m/sec or less, preferably 0.9 m/sec or more and more preferably 1.2 m/sec or more, and preferably 1.4 m/sec or less and more preferably 1.3 m/sec or less. <30> The method of producing an air-through nonwoven fabric for an absorbent article described in any one of the above items <27> to <29>, wherein the difference between the speed of hot air in the initial air-through treatment and the speed of hot air in the latter stage air-through treatment is more than 0 m/sec and 1.4 m/sec or less, preferably 0.4 m/sec or more and more preferably 0.8 m/sec or more, and preferably 1.2 m/sec or less and more preferably 1 m/sec or less. <31>
The method of producing an air-through nonwoven fabric for an absorbent article described in any one of the above items <21> to <30>, wherein the air-through processing has a plurality of air-through treatments, and wherein a temperature of hot air in the latter stage air-through treatment is higher than a temperature of hot air in the initial air-through treatment. <32>
The method of producing an air-through nonwoven fabric for an absorbent article described in the above item <31>, wherein the temperature of hot air in the initial air-through treatment is 85°C or more and 134°C or less, preferably 90°C or more and more preferably 100°C or more, and preferably 115°C or less and more preferably 105°C or less. <33>
The method of producing an air-through nonwoven fabric for an absorbent article described in the above item <31> or <32>, wherein the temperature of hot air in the latter stage air-through treatment is equal to or more than a melting point of the component on a surface of the fibres to be used and 145°C or less, preferably equal to or more than a melting point of the component on a surface of the fibres to be used, and preferably 137°C or less and more preferably 134°C or less. <34>
The method of producing an air-through nonwoven fabric for an absorbent article described in any one of the above items <31> to <33>, wherein the difference between the temperature of hot air in the initial air-through treatment and the temperature of hot air in the latter stage air-through treatment is more than 0°C and 60°C or less, preferably 20°C or more and more preferably 30°C or more, and preferably 40°C or less and more preferably 35°C or less. {0097} <35> The method of producing an air-through nonwoven fabric for an absorbent article described in any one of the above items <21> to <34>, containing one or both steps of: a step of collecting crosswise end portions of the web in the carding machine used in the opening step, and a step in which the air-through nonwoven fabric is partly collected, and a part of the collected air-through nonwoven fabric is cut and opened; wherein the collected web and the cut and opened part of the air-through nonwoven fabric are provided for the opening step.
{0098} <36> The method of producing an air-through nonwoven fabric for an absorbent article described in any one of the above items <21> to <35>, wherein the laminated web contains a plurality of kinds of fibres having different fibre diameters. <37>
The method of producing an air-through nonwoven fabric for an absorbent article described in any one of the above items <21> to <36>, wherein the laminated web contains fine fibres having a fibre diameter of 1 dtex or more and 2.2 dtex or less, preferably 1 dtex or more and more preferably 1.2 dtex or more, and preferably 2 dtex or less and more preferably 1.5 dtex or less. <38>
A method of producing an absorbent article, containing a step of incorporating the air-through nonwoven fabric for an absorbent article produced by the production method described in any one of the above items <21> to <37> into an absorbent article. <39>
The method of producing an absorbent article described in the above item <38>, containing a step of incorporating the air-through nonwoven fabric for an absorbent article into an absorbent article as a topsheet.
EXAMPLES
Hereinafter, the present invention will be described more in detail with reference to Examples, but the present invention is not limited thereto. A leftward arrow "4-" means that the content is the same as described in a left column indicated by the arrow.
(Example 1)
Using the production apparatus shown in Fig. 2, the nonwoven fabric sample of Example 1 was produced as shown below at a processing speed of 10 m/m in.
First, as raw material fibres (fine fibres) 71 for forming a fibre layer 1, core-sheath type (core: polyethylene terephthalate resin, sheath: polyethylene resin) thermoplastic fibres having a fibre diameter of 1.4 dtex were used. The raw material fibres 71 were used, whereby a plurality of times of opening treatment were applied thereto in an opening unit 101 and a carding unit 103 to prepare a single-layer web 81 having a basis weight of 10 g/m2.
In addition, as raw material fibres (thick fibres) 72 for forming a fibre layer 2, core-sheath type (core: polyethylene terephthalate resin, sheath: polyethylene resin) thermoplastic fibres having a fibre diameter of 4.4 dtex were used. The raw material fibres 72 were used, whereby a plurality of times of opening treatment were applied thereto in an opening unit 102 and a carding unit 104 to prepare a single-layer web 82 having a basis weight of 15 g/m2.
Next, in a laminated web-forming unit 105, the single-layer web 82 was laminated on the single-layer web 81 to form a laminated web 90. In a web calendering unit 106, web calendering was applied to the laminated web 90. In the web calendering unit 106, a steel calendering roll 106A on an upper layer side and a resin roll 106B (D hardness: 90 degrees) on a lower layer side were used, and a linear pressure was adjusted to 200 N/cm.
In a heat treatment unit 107, air-through processing in which two times of the air-through treatment shown in FIG. 3 were applied to the laminated web 95 subjected to the web calendering. The air speed and the temperature of the first air-through treatment and the second air-through treatment were adjusted as shown in Table 1. Thus, a nonwoven fabric sample in Example 1 was prepared.
In addition, in the producing method described above, operation of collecting crosswise end portions of the web formed and a part of the nonwoven fabric to return the collected materials to the opening step was not performed.
Therefore, a fibre diameter of the raw material fibres (fine fibres) 71 resulted in an average fibre diameter of the fibre layer 1, and a fibre diameter of the raw material fibres (thick fibres) 72 resulted in an average fibre diameter of the fibre layer 2.
{0102}
(Examples 2 to 7)
Nonwoven fabric samples in Examples 2 to 7 were prepared in the same manner as in Example 1 except that the temperature and the air speed of the first air-through treatment were adjusted as shown in Table 1.
{0103}
(Example 8)
A nonwoven fabric sample in Example 8 was prepared in the same manner as in Example 1 except that the web calendering was not performed, and the nonwoven fabric calendering shown in Table 1 was performed on the nonwoven fabric after air-through processing.
(Example 9)
A nonwoven fabric sample in Example 9 was prepared in the same manner as in Example 1 except that the fibre diameter of raw material fibres (fine fibres) for forming a fibre layer 1 was adjusted to 2.0 dtex, and the temperature and the air speed of the first air-through treatment were adjusted as shown in Table 1. {0105} (Example 10) A nonwoven fabric sample in Example 10 was prepared in the same manner as in Example 9 except that the fibre diameter of raw material fibres 72 for forming a fibre layer 2 was adjusted to 2.0 dtex.
(Example 11)
A nonwoven fabric sample in Example 11 was prepared in the same manner as in Example 10 except that the fibre diameter of raw material fibres (fine fibre) for forming a fibre layer 1 and the fibre diameter of raw material fibres 71 for forming a fibre layer 2 (lower layer) were adjusted to 1.4 dtex.
(Example 12)
A nonwoven fabric sample in Example 12 was prepared in the same manner as in Example 11 except that the temperature and the air speed of the first air-through treatment were adjusted as shown in Table 2.
(Example 13)
A nonwoven fabric sample in Example 13 was prepared in the same manner as in Example 12 except that the web calendering was not performed, and the nonwoven fabric calendering shown in Table 2 was performed on the nonwoven fabric after air-through processing.
(Comparative Example 1) A nonwoven fabric sample in Comparative Example 1 was prepared in the same manner as in Example 1 except that the web calendering was not performed.
(Comparative Example 2) A nonwoven fabric sample in Comparative Example 2 was prepared in the same manner as in Comparative Example 1 except that the fibre diameter of raw material fibres 71 for forming a fibre layer 2 (lower layer) was adjusted to 1.4 dtex.
(Tests) [1] Bulkiness (1) Thickness of nonwoven fabric sample under 0.05 kPa load Measurement was performed using a laser sensor (model number: ZS-5 LD80) and a controller (model number: ZS-LDC11) manufactured by OMRON Corporation as a laser type thickness gauge.
Upon measuring the thickness, a weight (0.05 kPa) was arranged between a tip portion of the laser sensor and the nonwoven fabric sample to be measured, and the thickness in such a pressure-applied state was measured.
Measurement was performed on 5 or more points, respectively, and an average value thereof was taken as the thickness. In addition, 0.05 kPa is a load assumed for an apparent thickness of the nonwoven fabric so as to avoid reduction of the thickness of the nonwoven fabric as much as possible.
(2) Thickness of nonwoven fabric sample under 7.64 kPa pressure A thickness (Ti) in a position in which a fibre mass portion of each nonwoven fabric sample was arranged, and a thickness (T2) in a position in which the fibre mass portion was not arranged were measured, respectively, based on the method described in (Method of measuring thickness of nonwoven fabric under 7.64 kPa pressure) mentioned above. A difference of the thickness (T3 = Ti -T2) was calculated.
[2] Friction A MIU value (Q1) in a position in which a fibre mass portion of each nonwoven fabric sample was arranged, and a MIU value (Q2) in a position in which the fibre mass portion was not arranged were measured, respectively, based on the method described in (Method of measuring average friction coefficient) mentioned above. A difference Q3 of the MIU values (= Q1 -Q2) was calculated.
[3] Pattern Presence or absence of the fibre mass portion was visually confirmed on each nonwoven fabric sample.
{0112} {Table 1}
Table 1
Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Ex 6 Lx? Ex 8
Specification Fibre composition Fibre PET/PE I
of nonwoven layer 1 1.35 dtex fabric 100% Fibre PET/PE 1 I 1 I 1 I layer 2 4.4 dtex 100% Basis weight g/m2 10/15 10/15 10/15 10/15 10/15 10/15 10/15 10/15 (Fibre layer 1/Fibre layer 2) Processing Web calendaring Upper: Steel roll N/cm 200 200 200 200 200 200 200 0 conditions Lower: Resin roll, D hardness: 90 degrees Temperature of first air-through treatment °C 136 136 115 105 105 105 85 136 Air speed of first air-through treatment m/sec 1.2 0.4 0.4 1.2 0.8 0.4 0.4 1.2 Temperature of second air-through treatment °C 136 136 136 136 136 136 136 136 Air speed of second air-through treatment m/sec 1.2 1.2 1.2 1.2 1.2 1.2 1.2 1.2 Nonwoven fabric calendaring Upper: Steel roll N/cm 0 0 0 0 0 0 0 200 Lower: Resin roll, D hardness: 90 degrees A plurality of times of opening treatment of f bres *1 YES YES YES YES YES YES YES YES Processing speed mhnin 10 10 10 10 10 10 10 10 Remarks: 'Ex' means Example according to this invention, Note *1: 'YES' means that the plurality of times of opening treatment of f bres was co ducted. (11
Table 1 (continued-1
Ex 9 Ex 10 C Ex 1 Specification of Fibre composition Fibre layer 1 PET/PE PET/PE PET/PE nonwoven fabric 2.0 dtex 2.0 dtex 1.35 dtex 100% 100% 100% Fibre layer 2 PET/PE PET/PE PET/PE 4.4 dtcx 2.0 dtcx 4.4 dtcx 100% 100% 100% Basis weight g/m2 10/15 10/15 10/15 (Fibre layer 1/Fibre layer 2) Processing Web calendaring Upper: Sled roll N/cin 200 200 0 conditions Lower: Resin roll, D hardness: 90 degrees Temperature of first air-through treatment °C 105 105 136 Air speed of first air-through treatment m/scc 0.4 0.4 1.2 Temperature of second air-through treatment °C 136 136 136 Air speed of second air-through treatment misee 1.2 1.2 1.2 Nonwoven fabric calendaring Upper: Steel roll Won 0 0 0 Lower: Resin roll, D hardness: 90 degrees A plurality of times of opening treatment of fibres *1 YES YES YES Processing speed m/min 10 10 10 Remarks: Ex means Example according to this invention, and 'C Ex' means Comparath e Example. Note *1: YES' means that the plurality of times of opening treatment of fibres was conducted.
Table 1 (continued-2) Ex 1 Ex 2 Ex 3 Ex 4 Ex 5 Ex 6 Ex 7 Ex 8 Bulkiness Thickness of nonwoven fabric (0.05 kPa) in 1.80 2.03 2.08 1.74 2.19 2.18 2.16 1.23 Thickness (T2) in position in which fibre mass portion of nonwoven fabric was not arranged (7.64 kPa) mm 0.13 0.17 0.17 0.17 0.16 0.15 0.15 0.13 Thickness (T1) in position in which fibre mass portion of nonwoven fabric was arranged (7.64 kPa) 111111 0.33 0.39 0.37 0.35 0.35 0.39 0.39 0.33 T3 = Ti -T2 mm 0.20 0.22 0.20 0.18 0.19 0.24 0.24 0.20 Feeling Average friction coefficient (Q2) in position in winch fibre mass portion of nonwoven fabric was not arranged ME] 2.00 2.10 2.03 2.10 2.13 2.11 2.06 2.03 Average friction coefficient (Q1) in position in which fibre mass portion of nonwoven fabric was arranged MN 2.31 2.30 2.26 2.30 2.34 2.31 2.30 2.30 Q3 = Q1 -Q2 MID 0.31 0.20 0.23 0.20 0.21 0.20 0.24 0.27 Pattern Presence or absence of fibre mass portion Present Present Present Present Present Present Present Present Position in which fibre mass portion was present Fibre Fibre Fibre Fibre Fibre Fibre Fibre Fibre layer 1 layer 1 layer 1 layer 1 layer 1 layer 1 layer 1 layer 1 Remarks: Fix! means Example according to this Tentioa Table 1 (continued-3) Ex 9 Exit) C Ex 1 Bulkiness Thickness of nonwoven fabric (0.05 kPa) mm 2.12 1.29 2.92 Thickness (T2) in position in which fibre mass portion of nonwoven fabric was not arranged (7.64 kPa) mm 0.17 0.14 0.16 Thickness (TI) in position in which fibre mass portion of nonwoven fabric was arranged (7.64 kPa) mm 0.32 0.32 0.57 T3 = Ti -T2 mm 0.15 0.18 0.41 Feeling Average friction coefficient (Q2) in position in which fibre mass portion of nonwoven fabric was not arranged MIU 2.05 1.98 2.22 Average friction coefficient (Q1) in position in which fibre mass portion of nonwoven fabric was arranged Mitt 2.16 2,16 3.05 Q3 = Q1-Q2 MIU 0.11 0.18 0.83 Pattern Presence or absence of fibre mass portion Present Present Present Position in which fibre mass portion was present Fibre layer 1 Fibre layers 1 and 2 Fibre layer 1 Remarks: 'Ex' means Example according to this invention, and 'C Ex' means Co npara e Example. 01 CO
{Table 2} Table 2
Ex 11 Ex 12 Ex 13 C Ex 2 Specification Fibre composition Fibre layer 1 PET/PE PET/PE of nonwoven 1.35 dtex 1.35 dtex Fabric 100% 100% Fibre layer 2 PET/PE PET/PE 1.35 dtex 1.35 dtex 100% 100% Basis weight g/m2 10/15 10/15 10/15 10/15 (Fibre layer 1/Fibre layer 2) Processing Web calencLaring Upper: Steel roll N/cm 200 200 0 0 conditions Lower: Resin roll, D hardness: 90 degrees Temperature of first air-through treatment °C 105 136 136 136 Air speed of first air-through treatment in/sec 0.4 1.2 1.2 1.2 Temperature of second air-through treatment °C 136 136 136 136 Air speed of second air-through treatment nilsec 1.2 1.2 1.2 1.2 Nonwoven fabric calendaring Upper: Steel roll N/cm 0 0 200 0 Lower: Resin roll, D hardness: 90 degrees A plurality of times of opening treatment of fibres *1 YES YES YES YES Processing speed nthnin 10 10 10 10 Remarks: 'Ex' means Example according to this invention, and 'C Ex' means Comparative Example. Note *1: 'YES' means that the plurality of times of opening treatment of fibres was conducted. cy)
Table 2 (continued-1) Exit Ex 12 Ex 13 C Ex 2 Bulkiness Thickness of nonwoven fabric (0.05 kPa) nun 1.15 0.97 0.80 2.57 Thickness (T2) in position in which fibre mass portion of nonwoven fabric was not arranged (7.64 kPa) mm 0.17 0.14 0.12 0.15 Thickness (TI) in position in which fibre mass portion of nonwoven fabric was arranged (7.64 kPa) mm 0.36 0.35 0.34 0.58 T3 = Ti -T2 mm 0.19 0.21 0.22 0.43 Feeling Average friction coefficient (Q2) in position in which fibre mass portion of nonwoven fabric was not arranged MILT 1.83 1.69 1.94 2.26 Average friction coefficient (Q1) in position in which fibre mass portion of nonwoven fabric was arranged MIU 2.28 2.30 2.30 3.02 Q3 = Q1 -Q2 MILT 0.45 0.61 0.36 0.76 Pattern Presence or absence of fibre mass portion Present Present Present Present Position in which fibre mass portion was present Fibre layers 1 and 2 Fibre layers 1 and 2 Fibre layers 1 and 2 Fibre layers 1 and 2 Remarks: 'Ex' means Example according to this invention, and 'C Ex' means Comparative Example.
As shown in Tables 1 and 2, in Examples 1 to 13, the difference T3 between the thickness 11 in the position in which the fibre mass portion was arranged and the thickness T2 in the position in which the fibre mass portion was not arranged under a pressure of 7.64 kPa was smaller, and bulkiness of the nonwoven fabric as a whole was superior, in comparison with Comparative Examples 1 and 2. In particular, among Examples, the nonwoven fabric subjected to heat treatment processing after the web calendering was formed into the nonwoven fabric which was thicker and superior in a feeling in the fibre mass portion than the material subjected to calendering after being formed into the nonwoven fabric.
In Examples 1 to 13, while the pattern of the fibre mass was confirmed, all the average friction coefficient (21 in the position in which the fibre mass portion was arranged, the average friction coefficient Q2 in the position in which the fibre mass portion was not arranged, and the difference 03 between both were smaller, and softer texture in the nonwoven fabric as a whole was realised, in comparison with Comparative Examples 1 and 2.
As described above, in Examples 1 to 13, the nonwoven fabrics were formed to be excellent in bulkiness and soft texture, and also in aesthetics provided with the pattern.
Having described our invention as related to this embodiments, aspects and Examples, it is our intention that the invention is not limited by any of the details of the description, unless otherwise specified, but rather is construed broadly within its spirit and scope as set out in the accompanying claims.
DESCRIPTION OF SYMBOLS {0116}
1 Fibre layer 2 Fibre layer 7 Fibre mass portion 8 Fibre mass layer (fibre layer containing fibre mass portion) 9 Non-fibre mass layer (fibre layer containing no fibre mass portion) Air-through nonwoven fabric for an absorbent article Production apparatus of air-through nonwoven fabric for an absorbent article 101, 102 Opening unit 103, 104 Carding unit 105 Laminated web-forming unit 106 Web calendering unit 106A, 10613 Calendering roll 107 Heat treatment unit (air-through processing unit) 117 First air-through treatment unit 127 Second air-through treatment unit 108 Cutting and opening unit 71, 72 Raw material fibres 81, 82 Single-layer web (or web) Laminated web 95 Laminated web subjected to web calendering
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