EP3946926A1 - Stretchable laminate sheet - Google Patents

Stretchable laminate sheet

Info

Publication number
EP3946926A1
EP3946926A1 EP20717301.4A EP20717301A EP3946926A1 EP 3946926 A1 EP3946926 A1 EP 3946926A1 EP 20717301 A EP20717301 A EP 20717301A EP 3946926 A1 EP3946926 A1 EP 3946926A1
Authority
EP
European Patent Office
Prior art keywords
stretchable
laminate sheet
nonwoven fabric
stretchable laminate
film
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.)
Withdrawn
Application number
EP20717301.4A
Other languages
German (de)
French (fr)
Inventor
Kioshi KUNIHIRO
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.)
3M Innovative Properties Co
Original Assignee
3M Innovative Properties Co
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 3M Innovative Properties Co filed Critical 3M Innovative Properties Co
Publication of EP3946926A1 publication Critical patent/EP3946926A1/en
Withdrawn legal-status Critical Current

Links

Classifications

    • 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
    • B32B3/00—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form
    • B32B3/26—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer
    • B32B3/30—Layered products comprising a layer with external or internal discontinuities or unevennesses, or a layer of non-planar shape; Layered products comprising a layer having particular features of form characterised by a particular shape of the outline of the cross-section of a continuous layer; characterised by a layer with cavities or internal voids ; characterised by an apertured layer characterised by a layer formed with recesses or projections, e.g. hollows, grooves, protuberances, ribs
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61F—FILTERS IMPLANTABLE INTO BLOOD VESSELS; PROSTHESES; DEVICES PROVIDING PATENCY TO, OR PREVENTING COLLAPSING OF, TUBULAR STRUCTURES OF THE BODY, e.g. STENTS; ORTHOPAEDIC, NURSING OR CONTRACEPTIVE DEVICES; FOMENTATION; TREATMENT OR PROTECTION OF EYES OR EARS; BANDAGES, DRESSINGS OR ABSORBENT PADS; FIRST-AID KITS
    • A61F13/00—Bandages or dressings; Absorbent pads
    • A61F13/15—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators
    • A61F13/45—Absorbent pads, e.g. sanitary towels, swabs or tampons for external or internal application to the body; Supporting or fastening means therefor; Tampon applicators characterised by the shape
    • A61F13/49—Absorbent articles specially adapted to be worn around the waist, e.g. diapers
    • A61F13/49007—Form-fitting, self-adjusting disposable diapers
    • A61F13/49009—Form-fitting, self-adjusting disposable diapers with elastic means
    • A61F13/4902—Form-fitting, self-adjusting disposable diapers with elastic means characterised by the elastic material
    • 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
    • B32B27/00—Layered products comprising a layer of synthetic resin
    • B32B27/12—Layered products comprising a layer of synthetic resin next to a fibrous or filamentary layer
    • 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
    • B32B5/02—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 structural features of a fibrous or filamentary layer
    • B32B5/022—Non-woven fabric
    • 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
    • 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
    • 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
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/08—Interconnection of layers by mechanical means
    • 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
    • B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
    • B32B7/04—Interconnection of layers
    • B32B7/12—Interconnection of layers using interposed adhesives or interposed materials with bonding properties
    • B32B7/14—Interconnection of layers using interposed adhesives or interposed materials with bonding properties applied in spaced arrangements, e.g. in stripes
    • 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
    • B32B2250/00—Layers arrangement
    • B32B2250/03—3 layers
    • 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
    • B32B2255/00—Coating on the layer surface
    • B32B2255/02—Coating on the layer surface on fibrous or filamentary layer
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/50—Properties of the layers or laminate having particular mechanical properties
    • B32B2307/51—Elastic
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/724—Permeability to gases, adsorption
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/726—Permeability to liquids, absorption
    • 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
    • B32B2307/00—Properties of the layers or laminate
    • B32B2307/70—Other properties
    • B32B2307/726—Permeability to liquids, absorption
    • B32B2307/7265—Non-permeable

Definitions

  • One aspect of the present invention relates to a stretchable laminate sheet including a stretchable film and a nonwoven fabric.
  • Elongatable web laminates are known for use in personal care articles such as diapers, training pants, adult incontinence devices, booties, and garments (see JP 2015-529581 T).
  • This web laminate is formed, for example, by laminating a nonwoven fabric layer to a multilayer film including a stretchable core layer sandwiched between skin layers.
  • a nonwoven fabric layer is laminated while the multilayer film is being drawn in the machine direction (MD), and the fiber direction of the nonwoven fabric layer coincides with the MD. That is, normally, a web laminate having stretchability in the MD, which is the fiber direction of the nonwoven fabric layer, has not been considered for a laminate that stretches in the cross machine direction (CD) perpendicular to the MD.
  • MD machine direction
  • CD cross machine direction
  • a stretchable laminate sheet includes a stretchable film, and a nonwoven fabric laminated on both sides of the stretchable film, of which at least one fiber direction has an alignment in one direction.
  • the nonwoven fabric includes a plurality of weld portions welded to the stretchable film, and a contraction portion contracting in a pleat shape between the plurality of weld portions and having a greater allowable amount of deployment in a direction orthogonal to the one direction than in the one direction.
  • the stretchable laminate sheet includes nonwoven fabrics laminated on both sides of the stretchable film, and the fiber direction of at least one of the nonwoven fabrics has an alignment in one direction. In manufacturing, this direction often coincides with the MD.
  • the stretchability, namely elastic recovery, of the stretchable laminate sheet depends on the stretchable film, and the stretchability of the stretchable film is regulated by the nonwoven fabric.
  • the nonwoven fabric includes a contraction portion that has a greater allowable amount of deployment in a direction orthogonal to the one direction (substantially CD) than in the one direction
  • the stretchable laminate sheet (substantially MD). Therefore, the stretchable laminate sheet elongates primarily in the CD rather than in the MD. As a result, it is possible to aggressively apply the stretchable laminate sheet to a product or the like that is advantageous in terms of manufacture or function when having stretchability in the CD direction.
  • the nonwoven fabric of the stretchable laminate sheet may include at least a plurality of long fibers, and the plurality of long fibers may have the alignment in one direction. In the case of the nonwoven fabric with the plurality of long fibers, one direction can be identified by the alignment of the long fibers.
  • the nonwoven fabric of the stretchable laminate sheet may include an extended portion that protrudes from the stretchable film, and the extended portions may overlap one another.
  • the regions where the extended portions overlap one another do not substantially elongate, so that it is possible to form a configuration in which stretchable portions and non-stretchable portions are differentiated.
  • a non-stretchable material having smaller stretchability than the stretchable film may be disposed between the extended portions of the stretchable laminate sheet according to an embodiment.
  • the non-stretchable material is disposed between the extended portions that protrude from the stretchable film, a step in the extended portions is suppressed, and the flat surface of the nonwoven fabric can be easily maintained.
  • the plurality of weld portions of the stretchable laminate sheet according to an embodiment may be disposed with non-uniform spacing in the direction orthogonal to the one direction.
  • the plurality of weld portions of the stretchable laminate sheet according to an embodiment may be disposed with uniform spacing in the direction orthogonal to the one direction.
  • a ratio of a thickness in a double-elongated state to a thickness in a resting state may be 70% or less.
  • the contraction portion in a cross-sectional view along the direction orthogonal to the one direction, the contraction portion may be continuous without breaking.
  • a stretchable laminate sheet that elongates in a direction orthogonal to a fiber direction of a nonwoven fabric.
  • FIG. l is a perspective view of a stretchable laminate sheet according to an embodiment.
  • FIG. 2 is a cross-sectional view taken along line II-II.
  • FIG. 3 is an enlarged plan view illustrating a region indicated by arrow A in FIG. 1.
  • FIG. 4 is a cross-sectional view taken along line IV-IV illustrated in FIG. 3.
  • FIG. 5 is a cross-sectional view illustrating a double-elongated state of the stretchable laminate sheet.
  • FIG. 6 is an enlarged plan view of a surface of the stretchable laminate sheet according to a modification of the embodiment.
  • FIG. 7 illustrates a manufacturing device for the stretchable laminate sheet.
  • FIG. 8 illustrates an example of a hygiene product and is a perspective view of a diaper with an ear portion.
  • FIG. 9 is a photograph corresponding to an enlarged plan view of the stretchable laminate sheet of Example 1.
  • FIG. 10 is a photograph corresponding to an enlarged cross-sectional view of the stretchable laminate sheet of Example 1, where FIG. 10(a) is a photograph of a cross section along the CD direction, and FIG. 10(b) is a photograph of a cross section along the MD direction.
  • FIG. 11 is a photograph of a cross section along the CD direction, showing the resting state of the stretchable laminate sheet according to Example 1.
  • FIG. 12 is a photograph of a cross section along the CD direction, showing the double- elongated state of the stretchable laminate sheet according to Example 1.
  • FIG. 13 is a cross section of the stretchable laminate sheet according to Comparative Example 1 along the CD direction, where FIG. 13(a) is a photograph of the resting state, and FIG. 13(b) is a photograph of the double-elongated state.
  • “at least one fiber direction” herein refers to the fiber direction of at least one of both nonwoven fabrics laminated on both sides of the stretchable film.
  • “fiber direction” refers to a direction in which most of fibers included in a nonwoven fabric are aligned due to the characteristic produced by the method for manufacturing the nonwoven fabric.
  • a“fiber direction” may be identified by microscopic observation of fibers, or may be identified as a direction in which the nonwoven fabric is difficult to break when pulled and broken.
  • “the fiber direction has an alignment in one direction” refers to an aspect in which the fiber direction is oriented in one direction as a trend.
  • “Allowable amount of deployment” refers to the limit length of the nonwoven fabric that is expanded by the deployment of the pleated contraction portion, which usually refers to the length of the nonwoven fabric that can elongate without breaking.
  • the allowable amount of deployment can be suitable for use applications, for example, can be 1.2 times, 1.5 times, 2 times, and the like.
  • “long fibers” are obtained by spun-bonding, melt-blowing, and the like, while“short fibers” are obtained by spunlacing, thermal bonding, and the like.
  • the long fibers may have, for example, a fiber length of at least 60 mm before cutting.
  • the stretchable laminate sheet 1 according to the embodiment can be suitably used as an ear portion of a disposable diaper or the like, for example, and can be suitably used in applications where aesthetics is desired and applications requiring excellent contact (skin feel or the like).
  • the substrate 2 including the stretchable film 3 is drawn out in the Machine Direction (MD) (hereinafter, referred to as the“MD direction”), and tensile tension is also applied to the substrate 2 in the Cross Machine Direction (CD) (hereinafter referred to as the“CD direction”), to activate the stretchable film 3.
  • MD Machine Direction
  • CD Cross Machine Direction
  • the nonwoven fabric 5 is laminated on both sides of the substrate 2 under tension, and is further subjected to ultrasonic welding or the like, so that the stretchable film 3 and the substrate 2 are integrated. Thereafter, the tension applied to the substrate 2 is released, and the stretchable film 3 contracts to form the stretchable laminate sheet 1 in the resting state.
  • the structure of the stretchable laminate sheet 1 will be described in detail below.
  • the stretchable laminate sheet 1 includes the substrate 2 and the nonwoven fabric 5 laminated on both sides of the substrate 2.
  • the substrate 2 includes the stretchable film 3 that is activated and has a desired stretchability, and a non-stretchable material 4 fixed to both side edges in the CD direction of the stretchable film 3.
  • the non- stretchable material 4 may be a member having a smaller stretchability than the stretchable film 3, and the non-stretchable material 4 according to the present embodiment is a nonwoven fabric.
  • the activation treatment refers to the process of pulling the stretchable film 3 to a length exceeding the elastic limit.
  • the activation treatment allows the stretchable film 3 to exhibit appropriate stretchability in order to be applied to a sanitary product or the like.
  • the nonwoven fabric 5 is laminated on both sides of the substrate 2.
  • the nonwoven fabric 5 includes a region laminated on the stretchable film 3 and a region laminated on the non- stretchable material 4.
  • the region of the nonwoven fabric 5 laminated on the stretchable film 3 is a main portion 5a
  • the region of the nonwoven fabric 5 laminated on the non-stretchable material 4 is an extended portion 5b that protrudes from the stretchable film 3.
  • the fiber direction of fibers F that form the nonwoven fabric 5 is oriented in one direction, and the nonwoven fabric 5 is then laminated on the surface of the substrate 2 so that the fiber direction coincides with the MD direction.
  • long fibers are mainly used in the manufacturing of the nonwoven fabric 5, and a plurality of long fibers are arranged in substantially the same direction. In other words, the fiber direction of the nonwoven fabric 5 substantially refers to the fiber direction of the long fibers.
  • both nonwoven fabrics 5 laminated on both sides of the substrate 2 mainly contain long fibers, and further aligned such that the fiber direction of the long fibers of both nonwoven fabrics 5 is substantially the MD direction (one direction).
  • both the nonwoven fabrics 5 only one may mainly contain long fibers, or may be aligned such that the fiber direction of only one is in the MD direction (one direction).
  • the substrate 2 and the nonwoven fabric 5 are integrated by a plurality of weld portions 7 A, 7B.
  • weld portions 7 A, 7B There are two types of weld portions 7 A, 7B according to the present embodiment.
  • One is a first weld portion 7A having a larger area in plan view, and the other is a second weld portion 7B having a smaller area than the first weld portion 7A.
  • the first weld portions 7A form a vertical row aligned in the MD direction.
  • the plurality of first weld portions 7A are arranged so as to have uniform spacing in the vertical row.
  • the plurality of second weld portions 7B form vertical rows aligned in the MD direction.
  • the plurality of second weld portions 7B are arranged so as to have substantially uniform spacing in the vertical row.
  • the vertical row of the first weld portions 7A and the vertical row of the second weld portions 7B are disposed alternately in the CD direction.
  • the plurality of first weld portions 7A and the second weld portions 7B are disposed with uniform spacing in the CD direction.
  • the plurality of weld portions 7C may be disposed with non-uniform spacing in the CD direction.
  • the nonwoven fabric 5 and the stretchable film 3 are mutually bonded and bound at the plurality of weld portions 7A, 7B, while they are free from mutual binding in regions other than the weld portions 7A, 7B. Then, after the nonwoven fabric 5 is bonded to the substrate 2 via the weld portions 7A, 7B, when the tension of the substrate 2 is released, the regions other than the weld portions 7A, 7B contract in a pleat shape, forming a contraction portion 6 (see FIGS. 4 and 5).
  • the contraction portion 6 is deployable so as to follow the elongation of the substrate 2. That is, the nonwoven fabric 5 is deployable in the CD direction without breaking, and the limit of the deployable length is the allowable amount of deployment. Usually, a difference between the state in which tension is applied for activation of the substrate 2 and the state in which the substrate 2 is reduced in size by releasing the tension corresponds to the allowable amount of deployment of the contraction portion 6 of the nonwoven fabric 5.
  • the nonwoven fabric 5 is laminated on the substrate 2 and thus integrated. That is, breaking which may be caused when the nonwoven fabric 5 is laminated on the substrate 2 and thus integrated before the activation, does not occur.
  • breaking which may be caused when the nonwoven fabric 5 is laminated on the substrate 2 and thus integrated before the activation, does not occur.
  • the contraction portion 6 is continuous without breaking.
  • Thickness Ta and Tb of the stretchable laminate sheet 1 are specified based on the contraction portion 6 of the nonwoven fabric 5.
  • the nonwoven fabric 5 laminated on one surface of the substrate 2 includes a pleated contraction portion 6, and the nonwoven fabric 5 laminated on the other surface of the substrate 2 includes a pleated contraction portion 6.
  • a portion separated from the substrate 2 in particular, the stretchable film 3
  • a portion separated from the substrate 2 in particular the stretchable film 3
  • one virtual plane including the apex 6a on one side, in generally parallel to the substrate 2 is assumed, and one virtual plane including the apex 6a on the other side, in generally parallel to the substrate 2, is assumed.
  • the distance between the one virtual plane and the other virtual plane is designated as the thickness Ta and Tb of the stretchable laminate sheet 1.
  • the thickness Tb of the stretchable laminate sheet 1 in the elongated state (for example, in the double-elongated state) is smaller than the thickness Ta of the stretchable laminate sheet 1 in the resting state.
  • the contraction portion 6 in the resting state has a pleat shape that steeply rises up from the first weld portion 7A.
  • the contraction portion 6 in the double-elongated state is deployed so that the pleats expand, and the slope of the gradient rising up from the first weld portion 7A is gentle.
  • the distance from the first weld portion 7A to the apex 6a of the pleated contraction portion 6 in the nonwoven fabric 5 of the stretchable laminate sheet 1 is smaller (shorter) in the double-elongated state than that in the resting state.
  • the stretchable laminate sheet 1 has smaller thickness Ta and Tb in the double-elongated state than that in the resting state.
  • the double-elongated state refers to a state of being pulled so that the length in the CD direction is doubled.
  • the thickness Ta and Tb of the stretchable laminate sheet 1 in the resting state may be, for example, from 200 pm to 5000 pm, from 400 pm to 3000 pm, or from 600 pm to 1000 pm.
  • the thickness Ta and Tb of the stretchable laminate sheet 1 in the double-elongated state may be, for example, from 50 pm to 4500 pm, from 200 pm to 2000 pm, or from 400 pm to 800 pm,
  • the stretchable film 3 may be formed from a resin material containing an elastomer.
  • the type of elastomer is not particularly limited, and examples thereof include styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene/butylene-styrene block copolymer (SEBS), polyurethane, ethylene copolymer (for example, ethylene-vinyl acetate, ethylene-propylene copolymer, ethylene- propylene-diene terpolymer), propylene oxide (PO), and the like.
  • a multilayer structure having a skin such as a polyolefin may be used on at least one surface of the core of the elastomer.
  • the resin material that composes the stretchable film 3 may contain other components besides the aforementioned components.
  • the resin material may contain a stiffening agent (for example, polyvinyl styrene, polystyrene, polya-methyl styrene, polyester, epoxy resin, polyolefin, coumarone-indene resin), viscosity reducing agent, plasticizer, tackifier (for example, aliphatic hydrocarbon tackifier, an aromatic hydrocarbon tackifier, a terpene resin tackifier, a hydrogenated terpene resin tackifier), dye, pigment, antioxidant, antistatic agent, adhesive, antiblocking agent, slip agent, heat stabilizer, light stabilizer, blowing agent, glass bubbles, starch, metal salt, microfibers, and the like.
  • a stiffening agent for example, polyvinyl styrene, polystyrene, polya-methyl styrene, polyester, epoxy resin, polyolef
  • the nonwoven fabric 5 can be widely used as a material that can be processed into the fibers F, and it is possible to prepare the nonwoven fabric 5 with the desired softness by appropriately combining materials and adjusting the fiber length, the thickness of the fibers F, and the like.
  • the material of the nonwoven fabric 5 includes, for example, polypropylene fiber, mixed fiber of polyester fiber and polyolefin fiber, or concentric type composite fiber of polyethylene terephthalate core covered by polyethylene.
  • the nonwoven fabric 5 may be prepared by spun-bonding, melt-blowing, spunlacing, or thermal bonding, for example.
  • a manufacturing device 20 for the stretchable laminate sheet 1 includes a first roll 21 that holds the stretchable film 3 forming the substrate 2; a second roll 22a and a third roll 22b that hold the nonwoven fabric 5 forming the substrate 2; a drawing unit (not illustrated) that activates the stretchable film 3 of the substrate 2 with tension; a first nonwoven fabric roll 23a and a second nonwoven fabric roll 23b that hold the nonwoven fabric 5 laminated on both sides of the substrate 2; a weld portion forming device 24 that forms a plurality of weld portions by partially crimping the laminated substrate 2 and nonwoven fabric 5 by embossing and performing ultrasonic welding; and a sheet roll 25 that holds the stretchable laminate sheet 1 integrated via the plurality of weld portions 7 A, 7B.
  • the stretchable film 3 is drawn out from the first roll 21, and the non-stretchable material 4 (nonwoven fabric) is drawn out from the second roll 22a and the third roll 22b.
  • the direction in which the stretchable film 3 and the non-stretchable material 4 are drawn out is the MD direction.
  • the non-stretchable material 4 is conveyed along both side edges of the stretchable film 3 in the CD direction and is fixed to both the side edges of the stretchable film 3.
  • the non- stretchable material 4 is fixed to the both sides of the stretchable film 3, so that the substrate 2 is formed (manufacturing of the substrate 2). Thereafter, tensile tension is applied to the substrate 2 in the CD direction to perform an activation treatment of the stretchable film 3 (activation).
  • the drawing unit pulls the non-stretchable material 4 of the substrate 2 in the CD direction while gripping it, and in particular, tensile tension is applied to the stretchable film 3 until the elastic limit is exceeded. Thereafter, the substrate 2 is conveyed to the subsequent step while being under tension in the CD direction. In the subsequent step, the nonwoven fabric 5 is drawn out from the first nonwoven fabric roll 23a and the second nonwoven fabric roll 23b, and is then laminated on both sides of the substrate 2 (nonwoven fabric lamination).
  • the substrate 2 having the nonwoven fabrics 5 laminated on both sides is fed out along a pattern roll 24a of the weld portion forming device 24.
  • the substrate 2 on which the nonwoven fabrics 5 are laminated is partially crimped by embossing, and is further subjected to ultrasonic welding or the like to thereby form the plurality of weld portions 7 A, 7B.
  • the substrate 2 and the nonwoven fabrics 5 are integrally formed by the plurality of weld portions 7 A, 7B, and the tension applied to the substrate 2 is further released to thereby form a pleated contraction portion 6 in the nonwoven fabric 5, so that the stretchable laminate sheet 1 is completed.
  • the completed stretchable laminate sheet 1 is wound around the sheet roll and then held.
  • the stretchable laminate sheet 1 As described above, the stretchable laminate sheet 1 according to the present invention
  • the embodiment includes the nonwoven fabrics 5 laminated on both sides of the stretchable film 3, and the fiber direction of at least one of the nonwoven fabrics 5 has an alignment in the MD direction (one direction).
  • the stretchability or elastic recovery of the stretchable laminate sheet 1 depends on the stretchable film 3, and the stretchability of the stretchable film 3 is regulated by the nonwoven fabric 5.
  • the nonwoven fabric 5 includes the contraction portion 6 having a greater allowable amount of deployment in the CD direction orthogonal to the MD direction than in the MD direction. Therefore, the stretchable laminate sheet 1 elongates primarily in the CD direction rather than in the MD direction. As a result, it is possible to aggressively apply the stretchable laminate sheet 1 to a product or the like that is advantageous in terms of manufacture or function when having stretchability in the CD direction.
  • the nonwoven fabric 5 of the stretchable laminate sheet 1 includes at least a plurality of long fibers, and the plurality of long fibers have, for example, an alignment in the MD direction (one direction).
  • one direction that is an alignment of the fiber direction can be identified by the alignment of the long fibers.
  • the nonwoven fabric 5 of the stretchable laminate sheet 1 includes the extended portion 5b that protrudes from the stretchable film 3, and the extended portions 5b indirectly overlap one another.
  • the regions where the extended portions 5b overlap one another do not substantially elongate, and thus it is possible to form a configuration in which stretchable portions and non-stretchable portions are differentiated.
  • the extended portions 5b according to the present embodiment indirectly overlap with the non-stretchable material 4 interposed therebetween, but may directly overlap without the non-stretchable material 4 interposed therebetween.
  • the non-stretchable material 4 is disposed between the extended portions 5b, and therefore, the step in the extended portions 5b, which tends to occur between the portion that sandwiches the stretchable film 3 and the portion that does not sandwich the stretchable film 3, is suppressed, and the flat surface of the nonwoven fabric 5 can be easily maintained.
  • the ear portion 31 has a lateral direction requiring stretchability and a longitudinal direction that does not require stretchability.
  • the ear portion 31 is cut out from the stretchable laminate sheet 1 so that the CD direction of the stretchable laminate sheet 1 is the lateral direction of the ear portion 31.
  • the ear portion 31 has a configuration in which non-stretchable regions 3 lb are disposed so as to sandwich a stretchable region 31a where the stretchable film 3 is disposed, a mechanical fastener such as a hook and loop fastener, for example, is provided in one non-stretchable regions 3 lb, and the other non-stretchable region 3 lb is a fixing portion that is fixed to a body 32 of a diaper 30.
  • a mechanical fastener such as a hook and loop fastener, for example
  • the diaper 30 includes an open-type diaper 30 as an example of the hygiene product.
  • the diaper 30 includes a rectangular body 32 including an outer liquid impermeable polymeric film and an inner liquid absorbing layer.
  • the body 32 is a portion that covers a crotch of a wearer such as an infant or the like.
  • a stretchable gather portion 33 is provided on both sides of the body.
  • An abdominal-side fixing portion 32a that contacts the wearer’s abdomen (lower belly) is provided at one end of the body 32 in the longitudinal direction, and a back-side fixing portion 32b that contacts the wearer’s back (waist) is provided on the other end.
  • the side contacting the wearer is the inner side and the opposite side is the outer side.
  • An engagement portion 32c of the mechanical fastener is fixed to the outer surface of the abdominal-side fixing portion 32a so as to cover a wide range in the width direction.
  • the ear portion 31 is provided on both sides of the back-side fixing portion 32b in the width direction.
  • An engagement portion 31c that engages with the engagement portion 32c to form a mechanical fastener is provided on the ear portion 31.
  • the engagement portion 3 lc of the ear portion 31 is formed by processing a hook sheet to match the shape of the ear portion 31 and then adhering the processed hook sheet to a predetermined position of the ear portion 31.
  • the diaper 30 is worn by the wearer so as to cover the wearer’s crotch with the body 32. Further, the abdominal-side fixing portion 32a is disposed so as to contact around the wearer’s lower belly, and the back-side fixing portion 32b is disposed so as to contact around the wearer’s waist. Next, the diaper 30 is worn by pulling the left and right ear portions 31, and then attaching the engagement portions 3 lc of the ear portions 31 to the engagement portion 32c of the abdominal-side fixing portion 32a.
  • a polypropylene spun-bond nonwoven fabric of 15 g/sqm was commonly used as a nonwoven fabric material in Examples.
  • the stretchable film which is the material of the stretchable laminate sheet, was a 35 g/sqm three-layer film of skin-core-skin, and polypropylene was used for each skin, and SIS based core was used.
  • Double elongation refers to the state where the stretchable laminate sheets of Example 1 and Comparative Example 1 in the resting state have been elongated to double the length in the CD direction.
  • the extended portion of the stretchable laminate sheet (see reference sign 5b in FIG. 2) was sandwiched between two plates, and was then widened until the width (length in the CD direction) of the contraction portion was doubled relative to the resting state.
  • the stretchable laminate sheet 1 (see FIGS. 9, 10, 11, and 12) of Example 1 is a nonwoven fabric material in which while tension is applied to the stretchable film 3 activated in the CD direction, the nonwoven fabrics 5 are laminated on both sides of the stretchable film 3, and then subjected to embossing in order to form the first weld portion 7 A and the second weld portion 7B.
  • the first weld portion 7A has a longitudinal dimension of about 1 mm and a width of about 0.2 mm.
  • the second weld portion 7B has a longitudinal dimension of about 0.5 mm and a width of about 0.1 mm.
  • the plurality of first weld portions 7A are disposed with uniform spacing in the direction orthogonal to the MD direction (CD direction), and the plurality of second weld portions 7B are disposed with uniform spacing in the direction orthogonal to the MD direction (CD direction).
  • the stretchable laminate sheet 1 according to Example 1 has a thickness in the unelongated resting state of 855 pm, and a thickness in the double-elongated state of 470 pm. As illustrated in FIGS. 11 and 12, the contraction portion 6 in the resting state has a pleat shape that steeply rises up from the first weld portion 7A. On the other hand, the contraction portion 6 in the double-elongated state is deployed so that the pleats expand, and the slope of the gradient rising from the first weld portion 7A is gentle.
  • the distance from the first weld portion 7A to the apex 6a of the pleated contraction portion 6 in the nonwoven fabric 5 of the stretchable laminate sheet 1 is smaller (shorter) in the double-elongated state than that in the resting state.
  • the stretchable laminate sheet 1 in the double-elongated state has a smaller thickness than that in the resting state.
  • the ratio of the thickness in the double-elongated state to the thickness in the resting state is approximately 50%, and 70 % or less.
  • a stretchable laminate sheet 100 (see FIG. 13) of Comparative Example 1 is a nonwoven fabric material in which nonwoven fabrics 102 are laminated on both sides of a stretchable film 101 in a resting state (without tensile tension), subjected to embossing in order to form a weld portion 103, and then activated by applying tensile tension thereto in the MD direction.
  • the nonwoven fabric 102 of the stretchable laminate sheet 100 does not include a pleated contraction portion.
  • tension is also applied to the nonwoven fabric 102 in combination with the activation of the stretchable film 101, and therefore, a location Fr at which the nonwoven fabric 102 breaks between the weld portions 103 can be confirmed.
  • the stretchable laminate sheet 100 of Comparative Example 1 has a thickness in the unelongated resting state of 655 pm, and a thickness in the double-elongated state of 630 pm. As illustrated in FIG. 13, the stretchable laminate sheet 100 of Comparative Example 1 does not include a substantially pleated contraction portion. As a result, when the resting state and the double-elongated state are compared, the difference in thickness of the stretchable laminate sheet 100 is small, and the ratio of the thickness in the double-elongated state to the thickness in the resting state is approximately 96%.

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Abstract

To provide a stretchable laminate sheet that can be elongated in the CD direction perpendicular to the MD direction. The stretchable laminate sheet according to an embodiment includes a stretchable film, and a nonwoven fabric laminated on both sides of the stretchable film, of which at least one fiber direction has an alignment in one direction. The nonwoven fabric includes a plurality of weld portions welded to the stretchable film, and a contraction portion contracting in a pleat shape between the plurality of weld portions and having a greater allowable amount of deployment in a direction orthogonal to the one direction than in the one direction.

Description

STRETCHABLE LAMINATE SHEET
Technical Field
One aspect of the present invention relates to a stretchable laminate sheet including a stretchable film and a nonwoven fabric.
Background
Elongatable web laminates are known for use in personal care articles such as diapers, training pants, adult incontinence devices, booties, and garments (see JP 2015-529581 T). This web laminate is formed, for example, by laminating a nonwoven fabric layer to a multilayer film including a stretchable core layer sandwiched between skin layers.
Summary
In known processes, a nonwoven fabric layer is laminated while the multilayer film is being drawn in the machine direction (MD), and the fiber direction of the nonwoven fabric layer coincides with the MD. That is, normally, a web laminate having stretchability in the MD, which is the fiber direction of the nonwoven fabric layer, has not been considered for a laminate that stretches in the cross machine direction (CD) perpendicular to the MD.
A stretchable laminate sheet according to an aspect of the present invention includes a stretchable film, and a nonwoven fabric laminated on both sides of the stretchable film, of which at least one fiber direction has an alignment in one direction. The nonwoven fabric includes a plurality of weld portions welded to the stretchable film, and a contraction portion contracting in a pleat shape between the plurality of weld portions and having a greater allowable amount of deployment in a direction orthogonal to the one direction than in the one direction.
The stretchable laminate sheet includes nonwoven fabrics laminated on both sides of the stretchable film, and the fiber direction of at least one of the nonwoven fabrics has an alignment in one direction. In manufacturing, this direction often coincides with the MD. The stretchability, namely elastic recovery, of the stretchable laminate sheet depends on the stretchable film, and the stretchability of the stretchable film is regulated by the nonwoven fabric. The nonwoven fabric includes a contraction portion that has a greater allowable amount of deployment in a direction orthogonal to the one direction (substantially CD) than in the one direction
(substantially MD). Therefore, the stretchable laminate sheet elongates primarily in the CD rather than in the MD. As a result, it is possible to aggressively apply the stretchable laminate sheet to a product or the like that is advantageous in terms of manufacture or function when having stretchability in the CD direction.
The nonwoven fabric of the stretchable laminate sheet according to an embodiment may include at least a plurality of long fibers, and the plurality of long fibers may have the alignment in one direction. In the case of the nonwoven fabric with the plurality of long fibers, one direction can be identified by the alignment of the long fibers.
The nonwoven fabric of the stretchable laminate sheet according to an embodiment may include an extended portion that protrudes from the stretchable film, and the extended portions may overlap one another. The regions where the extended portions overlap one another do not substantially elongate, so that it is possible to form a configuration in which stretchable portions and non-stretchable portions are differentiated.
A non-stretchable material having smaller stretchability than the stretchable film may be disposed between the extended portions of the stretchable laminate sheet according to an embodiment. When the non-stretchable material is disposed between the extended portions that protrude from the stretchable film, a step in the extended portions is suppressed, and the flat surface of the nonwoven fabric can be easily maintained.
The plurality of weld portions of the stretchable laminate sheet according to an embodiment may be disposed with non-uniform spacing in the direction orthogonal to the one direction.
The plurality of weld portions of the stretchable laminate sheet according to an embodiment may be disposed with uniform spacing in the direction orthogonal to the one direction.
In the stretchable laminate sheet according to an embodiment, a ratio of a thickness in a double-elongated state to a thickness in a resting state may be 70% or less.
In the stretchable laminate sheet according to an embodiment, in a cross-sectional view along the direction orthogonal to the one direction, the contraction portion may be continuous without breaking.
According to one aspect of the present invention, it is possible to provide a stretchable laminate sheet that elongates in a direction orthogonal to a fiber direction of a nonwoven fabric.
Brief Description of the Drawings
FIG. l is a perspective view of a stretchable laminate sheet according to an embodiment.
FIG. 2 is a cross-sectional view taken along line II-II.
FIG. 3 is an enlarged plan view illustrating a region indicated by arrow A in FIG. 1. FIG. 4 is a cross-sectional view taken along line IV-IV illustrated in FIG. 3.
FIG. 5 is a cross-sectional view illustrating a double-elongated state of the stretchable laminate sheet.
FIG. 6 is an enlarged plan view of a surface of the stretchable laminate sheet according to a modification of the embodiment.
FIG. 7 illustrates a manufacturing device for the stretchable laminate sheet.
FIG. 8 illustrates an example of a hygiene product and is a perspective view of a diaper with an ear portion.
FIG. 9 is a photograph corresponding to an enlarged plan view of the stretchable laminate sheet of Example 1.
FIG. 10 is a photograph corresponding to an enlarged cross-sectional view of the stretchable laminate sheet of Example 1, where FIG. 10(a) is a photograph of a cross section along the CD direction, and FIG. 10(b) is a photograph of a cross section along the MD direction.
FIG. 11 is a photograph of a cross section along the CD direction, showing the resting state of the stretchable laminate sheet according to Example 1.
FIG. 12 is a photograph of a cross section along the CD direction, showing the double- elongated state of the stretchable laminate sheet according to Example 1.
FIG. 13 is a cross section of the stretchable laminate sheet according to Comparative Example 1 along the CD direction, where FIG. 13(a) is a photograph of the resting state, and FIG. 13(b) is a photograph of the double-elongated state.
Detailed Description
The term“at least one fiber direction” herein refers to the fiber direction of at least one of both nonwoven fabrics laminated on both sides of the stretchable film. Furthermore,“fiber direction” refers to a direction in which most of fibers included in a nonwoven fabric are aligned due to the characteristic produced by the method for manufacturing the nonwoven fabric. For example, a“fiber direction” may be identified by microscopic observation of fibers, or may be identified as a direction in which the nonwoven fabric is difficult to break when pulled and broken. In addition,“the fiber direction has an alignment in one direction” refers to an aspect in which the fiber direction is oriented in one direction as a trend.
“Allowable amount of deployment” refers to the limit length of the nonwoven fabric that is expanded by the deployment of the pleated contraction portion, which usually refers to the length of the nonwoven fabric that can elongate without breaking. The allowable amount of deployment can be suitable for use applications, for example, can be 1.2 times, 1.5 times, 2 times, and the like. Additionally,“long fibers” are obtained by spun-bonding, melt-blowing, and the like, while“short fibers” are obtained by spunlacing, thermal bonding, and the like. The long fibers may have, for example, a fiber length of at least 60 mm before cutting.
Detailed descriptions of the embodiments according to the present invention are given below with reference to the attached drawings. Note that, in the description of the drawings, identical elements are denoted using the same reference signs, and duplicate descriptions thereof are omitted.
The stretchable laminate sheet 1 according to the embodiment (see FIG. 1) can be suitably used as an ear portion of a disposable diaper or the like, for example, and can be suitably used in applications where aesthetics is desired and applications requiring excellent contact (skin feel or the like).
When the stretchable laminate sheet 1 according to the embodiment is manufactured (see FIG. 7), the substrate 2 including the stretchable film 3 is drawn out in the Machine Direction (MD) (hereinafter, referred to as the“MD direction”), and tensile tension is also applied to the substrate 2 in the Cross Machine Direction (CD) (hereinafter referred to as the“CD direction”), to activate the stretchable film 3. The CD direction is a direction orthogonal to the MD direction on the surface along the stretchable film 3. Next, the nonwoven fabric 5 is laminated on both sides of the substrate 2 under tension, and is further subjected to ultrasonic welding or the like, so that the stretchable film 3 and the substrate 2 are integrated. Thereafter, the tension applied to the substrate 2 is released, and the stretchable film 3 contracts to form the stretchable laminate sheet 1 in the resting state. The structure of the stretchable laminate sheet 1 will be described in detail below.
As illustrated in FIGS. 1 and 2, the stretchable laminate sheet 1 includes the substrate 2 and the nonwoven fabric 5 laminated on both sides of the substrate 2. The substrate 2 includes the stretchable film 3 that is activated and has a desired stretchability, and a non-stretchable material 4 fixed to both side edges in the CD direction of the stretchable film 3. The non- stretchable material 4 may be a member having a smaller stretchability than the stretchable film 3, and the non-stretchable material 4 according to the present embodiment is a nonwoven fabric. In the manufacturing method described above, when the stretchable film 3 is activated, both of the non-stretchable materials 4 are gripped and then pulled in the CD direction, so that a stable activation treatment can be achieved. Note that the activation treatment refers to the process of pulling the stretchable film 3 to a length exceeding the elastic limit. The activation treatment allows the stretchable film 3 to exhibit appropriate stretchability in order to be applied to a sanitary product or the like.
The nonwoven fabric 5 is laminated on both sides of the substrate 2. The nonwoven fabric 5 includes a region laminated on the stretchable film 3 and a region laminated on the non- stretchable material 4. The region of the nonwoven fabric 5 laminated on the stretchable film 3 is a main portion 5a, and the region of the nonwoven fabric 5 laminated on the non-stretchable material 4 is an extended portion 5b that protrudes from the stretchable film 3. The fiber direction of fibers F that form the nonwoven fabric 5 is oriented in one direction, and the nonwoven fabric 5 is then laminated on the surface of the substrate 2 so that the fiber direction coincides with the MD direction. In addition, long fibers are mainly used in the manufacturing of the nonwoven fabric 5, and a plurality of long fibers are arranged in substantially the same direction. In other words, the fiber direction of the nonwoven fabric 5 substantially refers to the fiber direction of the long fibers.
As a further supplement, in the present embodiment, both nonwoven fabrics 5 laminated on both sides of the substrate 2 mainly contain long fibers, and further aligned such that the fiber direction of the long fibers of both nonwoven fabrics 5 is substantially the MD direction (one direction). However, of both the nonwoven fabrics 5, only one may mainly contain long fibers, or may be aligned such that the fiber direction of only one is in the MD direction (one direction).
As illustrated in FIG. 3, the substrate 2 and the nonwoven fabric 5 are integrated by a plurality of weld portions 7 A, 7B. There are two types of weld portions 7 A, 7B according to the present embodiment. One is a first weld portion 7A having a larger area in plan view, and the other is a second weld portion 7B having a smaller area than the first weld portion 7A. The first weld portions 7A form a vertical row aligned in the MD direction. The plurality of first weld portions 7A are arranged so as to have uniform spacing in the vertical row. The plurality of second weld portions 7B form vertical rows aligned in the MD direction. The plurality of second weld portions 7B are arranged so as to have substantially uniform spacing in the vertical row.
The vertical row of the first weld portions 7A and the vertical row of the second weld portions 7B are disposed alternately in the CD direction. The plurality of first weld portions 7A and the second weld portions 7B are disposed with uniform spacing in the CD direction.
Note that as the weld portion 7C according to the modification of the embodiment, as illustrated in FIG. 6, the plurality of weld portions 7C may be disposed with non-uniform spacing in the CD direction.
As described above, the nonwoven fabric 5 and the stretchable film 3 are mutually bonded and bound at the plurality of weld portions 7A, 7B, while they are free from mutual binding in regions other than the weld portions 7A, 7B. Then, after the nonwoven fabric 5 is bonded to the substrate 2 via the weld portions 7A, 7B, when the tension of the substrate 2 is released, the regions other than the weld portions 7A, 7B contract in a pleat shape, forming a contraction portion 6 (see FIGS. 4 and 5). The contraction portion 6 is deployable so as to follow the elongation of the substrate 2. That is, the nonwoven fabric 5 is deployable in the CD direction without breaking, and the limit of the deployable length is the allowable amount of deployment. Usually, a difference between the state in which tension is applied for activation of the substrate 2 and the state in which the substrate 2 is reduced in size by releasing the tension corresponds to the allowable amount of deployment of the contraction portion 6 of the nonwoven fabric 5.
As a further supplement, under the state in which tension is applied to the substrate 2 to activate the stretchable film 3, the nonwoven fabric 5 is laminated on the substrate 2 and thus integrated. That is, breaking which may be caused when the nonwoven fabric 5 is laminated on the substrate 2 and thus integrated before the activation, does not occur. As a result, in the stretchable laminate sheet 1 according to the present embodiment, in a cross-sectional view along the CD direction orthogonal to the MD direction (one direction), the contraction portion 6 is continuous without breaking.
Thickness Ta and Tb of the stretchable laminate sheet 1 are specified based on the contraction portion 6 of the nonwoven fabric 5. Specifically, when the stretchable laminate sheet 1 is viewed microscopically, the nonwoven fabric 5 laminated on one surface of the substrate 2 includes a pleated contraction portion 6, and the nonwoven fabric 5 laminated on the other surface of the substrate 2 includes a pleated contraction portion 6. Among the pleated contraction portions 6 of one nonwoven fabric 5, a portion separated from the substrate 2 (in particular, the stretchable film 3) is identified as an apex 6a on one side. Subsequently, among the pleated contraction portions 6 of the other nonwoven fabric 5, a portion separated from the substrate 2 (in particular the stretchable film 3) is identified as an apex 6a on the other side. Next, one virtual plane including the apex 6a on one side, in generally parallel to the substrate 2, is assumed, and one virtual plane including the apex 6a on the other side, in generally parallel to the substrate 2, is assumed. Then, the distance between the one virtual plane and the other virtual plane is designated as the thickness Ta and Tb of the stretchable laminate sheet 1.
The thickness Tb of the stretchable laminate sheet 1 in the elongated state (for example, in the double-elongated state) is smaller than the thickness Ta of the stretchable laminate sheet 1 in the resting state. For example, as illustrated in FIG. 4, the contraction portion 6 in the resting state has a pleat shape that steeply rises up from the first weld portion 7A. On the other hand, the contraction portion 6 in the double-elongated state is deployed so that the pleats expand, and the slope of the gradient rising up from the first weld portion 7A is gentle. That is, the distance from the first weld portion 7A to the apex 6a of the pleated contraction portion 6 in the nonwoven fabric 5 of the stretchable laminate sheet 1 is smaller (shorter) in the double-elongated state than that in the resting state. As a result, the stretchable laminate sheet 1 has smaller thickness Ta and Tb in the double-elongated state than that in the resting state. Note that the double-elongated state refers to a state of being pulled so that the length in the CD direction is doubled.
The thickness Ta and Tb of the stretchable laminate sheet 1 in the resting state may be, for example, from 200 pm to 5000 pm, from 400 pm to 3000 pm, or from 600 pm to 1000 pm.
In addition, the thickness Ta and Tb of the stretchable laminate sheet 1 in the double-elongated state may be, for example, from 50 pm to 4500 pm, from 200 pm to 2000 pm, or from 400 pm to 800 pm,
Next, the materials and the like of each structure of the stretchable laminate sheet 1 will be described. The stretchable film 3 may be formed from a resin material containing an elastomer. The type of elastomer is not particularly limited, and examples thereof include styrene-isoprene-styrene block copolymer (SIS), styrene-butadiene-styrene block copolymer (SBS), styrene-ethylene/butylene-styrene block copolymer (SEBS), polyurethane, ethylene copolymer (for example, ethylene-vinyl acetate, ethylene-propylene copolymer, ethylene- propylene-diene terpolymer), propylene oxide (PO), and the like. In view of the convenience of the manufacturing process, a multilayer structure having a skin such as a polyolefin may be used on at least one surface of the core of the elastomer.
The resin material that composes the stretchable film 3 may contain other components besides the aforementioned components. For example, the resin material may contain a stiffening agent (for example, polyvinyl styrene, polystyrene, polya-methyl styrene, polyester, epoxy resin, polyolefin, coumarone-indene resin), viscosity reducing agent, plasticizer, tackifier (for example, aliphatic hydrocarbon tackifier, an aromatic hydrocarbon tackifier, a terpene resin tackifier, a hydrogenated terpene resin tackifier), dye, pigment, antioxidant, antistatic agent, adhesive, antiblocking agent, slip agent, heat stabilizer, light stabilizer, blowing agent, glass bubbles, starch, metal salt, microfibers, and the like.
The nonwoven fabric 5 can be widely used as a material that can be processed into the fibers F, and it is possible to prepare the nonwoven fabric 5 with the desired softness by appropriately combining materials and adjusting the fiber length, the thickness of the fibers F, and the like. The material of the nonwoven fabric 5 includes, for example, polypropylene fiber, mixed fiber of polyester fiber and polyolefin fiber, or concentric type composite fiber of polyethylene terephthalate core covered by polyethylene. The nonwoven fabric 5 may be prepared by spun-bonding, melt-blowing, spunlacing, or thermal bonding, for example.
Next, with reference to FIG. 7, a method of manufacturing the stretchable laminate sheet 1 according to the present embodiment will be described. A manufacturing device 20 for the stretchable laminate sheet 1 includes a first roll 21 that holds the stretchable film 3 forming the substrate 2; a second roll 22a and a third roll 22b that hold the nonwoven fabric 5 forming the substrate 2; a drawing unit (not illustrated) that activates the stretchable film 3 of the substrate 2 with tension; a first nonwoven fabric roll 23a and a second nonwoven fabric roll 23b that hold the nonwoven fabric 5 laminated on both sides of the substrate 2; a weld portion forming device 24 that forms a plurality of weld portions by partially crimping the laminated substrate 2 and nonwoven fabric 5 by embossing and performing ultrasonic welding; and a sheet roll 25 that holds the stretchable laminate sheet 1 integrated via the plurality of weld portions 7 A, 7B.
The stretchable film 3 is drawn out from the first roll 21, and the non-stretchable material 4 (nonwoven fabric) is drawn out from the second roll 22a and the third roll 22b. The direction in which the stretchable film 3 and the non-stretchable material 4 are drawn out is the MD direction. The non-stretchable material 4 is conveyed along both side edges of the stretchable film 3 in the CD direction and is fixed to both the side edges of the stretchable film 3. The non- stretchable material 4 is fixed to the both sides of the stretchable film 3, so that the substrate 2 is formed (manufacturing of the substrate 2). Thereafter, tensile tension is applied to the substrate 2 in the CD direction to perform an activation treatment of the stretchable film 3 (activation). In the activation, the drawing unit pulls the non-stretchable material 4 of the substrate 2 in the CD direction while gripping it, and in particular, tensile tension is applied to the stretchable film 3 until the elastic limit is exceeded. Thereafter, the substrate 2 is conveyed to the subsequent step while being under tension in the CD direction. In the subsequent step, the nonwoven fabric 5 is drawn out from the first nonwoven fabric roll 23a and the second nonwoven fabric roll 23b, and is then laminated on both sides of the substrate 2 (nonwoven fabric lamination).
The substrate 2 having the nonwoven fabrics 5 laminated on both sides is fed out along a pattern roll 24a of the weld portion forming device 24. Here, the substrate 2 on which the nonwoven fabrics 5 are laminated is partially crimped by embossing, and is further subjected to ultrasonic welding or the like to thereby form the plurality of weld portions 7 A, 7B. The substrate 2 and the nonwoven fabrics 5 are integrally formed by the plurality of weld portions 7 A, 7B, and the tension applied to the substrate 2 is further released to thereby form a pleated contraction portion 6 in the nonwoven fabric 5, so that the stretchable laminate sheet 1 is completed. The completed stretchable laminate sheet 1 is wound around the sheet roll and then held.
As described above, the stretchable laminate sheet 1 according to the present
embodiment includes the nonwoven fabrics 5 laminated on both sides of the stretchable film 3, and the fiber direction of at least one of the nonwoven fabrics 5 has an alignment in the MD direction (one direction). The stretchability or elastic recovery of the stretchable laminate sheet 1 depends on the stretchable film 3, and the stretchability of the stretchable film 3 is regulated by the nonwoven fabric 5. The nonwoven fabric 5 includes the contraction portion 6 having a greater allowable amount of deployment in the CD direction orthogonal to the MD direction than in the MD direction. Therefore, the stretchable laminate sheet 1 elongates primarily in the CD direction rather than in the MD direction. As a result, it is possible to aggressively apply the stretchable laminate sheet 1 to a product or the like that is advantageous in terms of manufacture or function when having stretchability in the CD direction.
Furthermore, the nonwoven fabric 5 of the stretchable laminate sheet 1 includes at least a plurality of long fibers, and the plurality of long fibers have, for example, an alignment in the MD direction (one direction). In the case of the nonwoven fabric 5 with the plurality of long fibers, one direction that is an alignment of the fiber direction can be identified by the alignment of the long fibers.
Furthermore, the nonwoven fabric 5 of the stretchable laminate sheet 1 includes the extended portion 5b that protrudes from the stretchable film 3, and the extended portions 5b indirectly overlap one another. The regions where the extended portions 5b overlap one another do not substantially elongate, and thus it is possible to form a configuration in which stretchable portions and non-stretchable portions are differentiated. Note that the extended portions 5b according to the present embodiment indirectly overlap with the non-stretchable material 4 interposed therebetween, but may directly overlap without the non-stretchable material 4 interposed therebetween.
In addition, in the stretchable laminate sheet 1 according to the present embodiment, the non-stretchable material 4 is disposed between the extended portions 5b, and therefore, the step in the extended portions 5b, which tends to occur between the portion that sandwiches the stretchable film 3 and the portion that does not sandwich the stretchable film 3, is suppressed, and the flat surface of the nonwoven fabric 5 can be easily maintained.
Next, processes applied to an ear portion 31 of a diaper will be described with reference to FIG. 8. The ear portion 31 has a lateral direction requiring stretchability and a longitudinal direction that does not require stretchability. When the ear portion 31 is manufactured, the ear portion 31 is cut out from the stretchable laminate sheet 1 so that the CD direction of the stretchable laminate sheet 1 is the lateral direction of the ear portion 31. In this state, the ear portion 31 has a configuration in which non-stretchable regions 3 lb are disposed so as to sandwich a stretchable region 31a where the stretchable film 3 is disposed, a mechanical fastener such as a hook and loop fastener, for example, is provided in one non-stretchable regions 3 lb, and the other non-stretchable region 3 lb is a fixing portion that is fixed to a body 32 of a diaper 30.
The diaper 30 includes an open-type diaper 30 as an example of the hygiene product. The diaper 30 includes a rectangular body 32 including an outer liquid impermeable polymeric film and an inner liquid absorbing layer. The body 32 is a portion that covers a crotch of a wearer such as an infant or the like. A stretchable gather portion 33 is provided on both sides of the body.
An abdominal-side fixing portion 32a that contacts the wearer’s abdomen (lower belly) is provided at one end of the body 32 in the longitudinal direction, and a back-side fixing portion 32b that contacts the wearer’s back (waist) is provided on the other end. In the abdominal-side fixing portion 32a and the back-side fixing portion 32b, the side contacting the wearer is the inner side and the opposite side is the outer side.
An engagement portion 32c of the mechanical fastener is fixed to the outer surface of the abdominal-side fixing portion 32a so as to cover a wide range in the width direction. The ear portion 31 is provided on both sides of the back-side fixing portion 32b in the width direction.
An engagement portion 31c that engages with the engagement portion 32c to form a mechanical fastener is provided on the ear portion 31. The engagement portion 3 lc of the ear portion 31 is formed by processing a hook sheet to match the shape of the ear portion 31 and then adhering the processed hook sheet to a predetermined position of the ear portion 31.
The diaper 30 is worn by the wearer so as to cover the wearer’s crotch with the body 32. Further, the abdominal-side fixing portion 32a is disposed so as to contact around the wearer’s lower belly, and the back-side fixing portion 32b is disposed so as to contact around the wearer’s waist. Next, the diaper 30 is worn by pulling the left and right ear portions 31, and then attaching the engagement portions 3 lc of the ear portions 31 to the engagement portion 32c of the abdominal-side fixing portion 32a.
Examples
Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the examples. Note that a polypropylene spun-bond nonwoven fabric of 15 g/sqm was commonly used as a nonwoven fabric material in Examples. The stretchable film, which is the material of the stretchable laminate sheet, was a 35 g/sqm three-layer film of skin-core-skin, and polypropylene was used for each skin, and SIS based core was used.
As described below, in Example 1 and Comparative Example 1, a double elongation was performed by pulling the stretchable laminate sheet from the resting state in the CD direction to double the elongation. Double elongation refers to the state where the stretchable laminate sheets of Example 1 and Comparative Example 1 in the resting state have been elongated to double the length in the CD direction. Specifically, the extended portion of the stretchable laminate sheet (see reference sign 5b in FIG. 2) was sandwiched between two plates, and was then widened until the width (length in the CD direction) of the contraction portion was doubled relative to the resting state.
Example 1
The stretchable laminate sheet 1 (see FIGS. 9, 10, 11, and 12) of Example 1 is a nonwoven fabric material in which while tension is applied to the stretchable film 3 activated in the CD direction, the nonwoven fabrics 5 are laminated on both sides of the stretchable film 3, and then subjected to embossing in order to form the first weld portion 7 A and the second weld portion 7B. The first weld portion 7A has a longitudinal dimension of about 1 mm and a width of about 0.2 mm. The second weld portion 7B has a longitudinal dimension of about 0.5 mm and a width of about 0.1 mm. The plurality of first weld portions 7A are disposed with uniform spacing in the direction orthogonal to the MD direction (CD direction), and the plurality of second weld portions 7B are disposed with uniform spacing in the direction orthogonal to the MD direction (CD direction).
The stretchable laminate sheet 1 according to Example 1 has a thickness in the unelongated resting state of 855 pm, and a thickness in the double-elongated state of 470 pm. As illustrated in FIGS. 11 and 12, the contraction portion 6 in the resting state has a pleat shape that steeply rises up from the first weld portion 7A. On the other hand, the contraction portion 6 in the double-elongated state is deployed so that the pleats expand, and the slope of the gradient rising from the first weld portion 7A is gentle. That is, the distance from the first weld portion 7A to the apex 6a of the pleated contraction portion 6 in the nonwoven fabric 5 of the stretchable laminate sheet 1 is smaller (shorter) in the double-elongated state than that in the resting state.
As a result, the stretchable laminate sheet 1 in the double-elongated state has a smaller thickness than that in the resting state. In the case of the stretchable laminate sheet 1 of Example 1, the ratio of the thickness in the double-elongated state to the thickness in the resting state is approximately 50%, and 70 % or less.
Comparative Example 1
A stretchable laminate sheet 100 (see FIG. 13) of Comparative Example 1 is a nonwoven fabric material in which nonwoven fabrics 102 are laminated on both sides of a stretchable film 101 in a resting state (without tensile tension), subjected to embossing in order to form a weld portion 103, and then activated by applying tensile tension thereto in the MD direction. In Comparative Example 1, the nonwoven fabric 102 of the stretchable laminate sheet 100 does not include a pleated contraction portion. Furthermore, in Comparative Example 1, tension is also applied to the nonwoven fabric 102 in combination with the activation of the stretchable film 101, and therefore, a location Fr at which the nonwoven fabric 102 breaks between the weld portions 103 can be confirmed.
The stretchable laminate sheet 100 of Comparative Example 1 has a thickness in the unelongated resting state of 655 pm, and a thickness in the double-elongated state of 630 pm. As illustrated in FIG. 13, the stretchable laminate sheet 100 of Comparative Example 1 does not include a substantially pleated contraction portion. As a result, when the resting state and the double-elongated state are compared, the difference in thickness of the stretchable laminate sheet 100 is small, and the ratio of the thickness in the double-elongated state to the thickness in the resting state is approximately 96%.

Claims

What is claimed is:
1. A stretchable laminate sheet comprising: a stretchable film; and
a nonwoven fabric laminated on both sides of the stretchable film, of which at least one fiber direction has an alignment in one direction,
wherein the nonwoven fabric includes:
a plurality of weld portions welded to the stretchable film; and
a contraction portion contracting in a pleat shape between the plurality of weld portions and having a greater allowable amount of deployment in a direction orthogonal to the one direction than in the one direction.
2. The stretchable laminate sheet according to claim 1, wherein the nonwoven fabric comprises at least a plurality of long fibers, and
the plurality of long fibers have the alignment in one direction.
3. The stretchable laminate sheet according to claim 1 or 2, wherein the nonwoven fabric comprises an extended portion that protrudes from the stretchable film, and
the extended portions overlap one another.
4. The stretchable laminate sheet according to claim 3, wherein a non-stretchable material having smaller stretchability than the stretchable film is disposed between the extended portions.
5. The stretchable laminate sheet according to any one of claims 1 to 4, wherein the plurality of weld portions are disposed with non-uniform spacing in the direction orthogonal to the one direction.
6. The stretchable laminate sheet according to any one of claims 1 to 4, wherein the plurality of weld portions are disposed with uniform spacing in the direction orthogonal to the one direction.
7. The stretchable laminate sheet according to any one of claims 1 to 6, wherein a ratio of a thickness in a double-elongated state to a thickness in a resting state is 70% or less.
8. The stretchable laminate sheet according to any one of claims 1 to 7, wherein, in a cross-sectional view along the direction orthogonal to the one direction, the contraction portion is continuous without breaking.
EP20717301.4A 2019-03-29 2020-03-25 Stretchable laminate sheet Withdrawn EP3946926A1 (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
JP2019067630A JP2020163758A (en) 2019-03-29 2019-03-29 Elastic laminated sheet
PCT/IB2020/052799 WO2020201919A1 (en) 2019-03-29 2020-03-25 Stretchable laminate sheet

Publications (1)

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EP3946926A1 true EP3946926A1 (en) 2022-02-09

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EP20717301.4A Withdrawn EP3946926A1 (en) 2019-03-29 2020-03-25 Stretchable laminate sheet

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EP (1) EP3946926A1 (en)
JP (1) JP2020163758A (en)
CN (1) CN113661057A (en)
WO (1) WO2020201919A1 (en)

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP3652695B2 (en) * 2003-07-30 2005-05-25 ユニ・チャーム株式会社 Disposable diapers
US9469091B2 (en) 2012-08-08 2016-10-18 3M Innovative Properties Company Method of making extensible web laminates
WO2016185999A1 (en) * 2015-05-19 2016-11-24 株式会社瑞光 Stretchable laminate sheet and disposable article of wear

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CN113661057A (en) 2021-11-16
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