Outer material and backpacks using this outer material

Abstract

A skin material, wherein the bending hysteresis moment 2HB (gf·cm / cm) and thickness h (mm) when bent in the surface direction satisfy the following formulas (I) and (II): 2HB≤15h-10 (I) 1.0≤h≤2.5 (II).

Description

Technical Field

[0001] This invention relates to skin materials and backpacks using the skin materials. Background Technology

[0002] Previously, it was known that bags such as ransel, rucksack, knapsack, backpack, daypack, schoolbag, shoulder bag, waist bag, and hipbag came in various types and shapes depending on their intended use.

[0003] Various proposals have been put forward regarding the various components that make up such bags and their outer materials.

[0004] For example, Patent Document 1 describes a shoulder strap comprising: a mesh structure formed by fusing randomly looped continuous linear bodies of thermoplastic resin at their intersections; and a synthetic leather sheet on a nonwoven or woven substrate layer having a resin layer formed of synthetic resin, wherein the synthetic leather sheet preferably has a stiffness of 0.1 mN or more and 1 mN or less, as determined by the Gurley flexural resilience test. This shoulder strap is positioned on the body side of the user of the aforementioned article-containing device. Patent Document 1 describes that by possessing characteristics such as low stiffness and using a suitable synthetic leather sheet on the body side rather than the surface side, this shoulder strap can adequately distribute the load applied to the body, even if it is narrow.

[0005] Patent Document 2 describes a shoulder strap material in which at least a portion uses a sheet (A) having substantially continuous convex portions and adjacent concave portions on its surface. The height difference between the convex and concave portions, the vertical projected area of ​​adjacent concave portions, the average spacing between the concave portions, and the 20% compressive stress in the thickness direction are within specific ranges. Patent Document 2 also describes that, with respect to this shoulder strap material, using the sheet (A) in the portion that abuts against the shoulder provides good cushioning, fit, and wearing comfort.

[0006] Patent document 3 describes an artificial leather comprising a surface layer (1), a middle layer (A), and a back layer (B). The surface layer (1) is formed of polyurethane resin. The middle layer (A) is a fibrous layer of nylon microfiber nonwoven fabric impregnated and solidified with porous polyurethane resin. The back layer (B) is a fibrous layer of polyester microfiber nonwoven fabric impregnated and solidified with porous polyurethane resin. The thickness ratio (A) / (B) of the middle layer to the back layer is 0.5 to 5. Patent document 3 also describes that this artificial leather is particularly suitable as a raw material for school bags. School bags using this material in the main body flap, front section, shoulder straps, and paneling sections have a high-end feel, with delicate pleats on the flap and excellent cushioning.

[0007] Patent Document 4 discloses a lid material for a cap-type package, wherein a colored layer is formed on the back side of a fiber substrate layer, and a polyurethane surface layer comprising an adhesive polyurethane and polyurethane microparticles is laminated on the side opposite to the back side. Patent Document 4 describes that the lid material for a cap-type package has a smooth and glossy surface, bright colors, good wrinkle resistance and feel, and excellent bending resistance.

[0008] Patent Document 5 describes a schoolbag in which a straight-line reinforcing material (10) formed of shape memory material is fixed along the left and right sides (7a) of a cover (7) with a buckle (6) attached to its lower end. Patent Document 5 describes that, through the action of the shape memory material, the schoolbag will naturally stand up when the buckle (6) is removed, thus making it easy to open the cover (7). Furthermore, even if the cover (7) is deformed due to a load exceeding the elastic limit of the reinforcing material (10), it can easily return to its original shape, so the appearance will not deteriorate.

[0009] Existing technical documents

[0010] Patent documents

[0011] Patent Document 1: Japanese Patent Application Publication No. 2021-58438

[0012] Patent Document 2: Japanese Patent Application Publication No. 2007-412

[0013] Patent Document 3: Japanese Patent Application Publication No. 2000-239974

[0014] Patent Document 4: Japanese Patent Application Publication No. 2010-194242

[0015] Patent Document 5: Japanese Utility Model Application No. 3011706 Summary of the Invention

[0016] The problem that the invention aims to solve

[0017] In recent years, bags have not only been required to be durable, but also increasingly to have a sense of luxury.

[0018] For shoulder straps and flaps of backpacks and other similar items, thickening the outer material makes it less prone to sharp bends, thus reducing wrinkles and creating a sense of tension and sophistication. However, if the outer material is too thick, bending can create deep indentations on the inner surface, leading to a phenomenon known as "bending." Furthermore, the strain generated within the outer material due to bending can easily create large wrinkles that detract from the sense of surface tension. Moreover, once wrinkles form due to internal strain, they are difficult to remove, resulting in a loss of the premium feel of the outer material.

[0019] In addition, by thinning the outer skin material, the responsiveness to bending is improved, and buckling is less likely to occur. However, if the outer skin material is thin, the object's cushioning against contact pressure is reduced, the surface is more prone to wear and peeling, especially when used in straps, covers, etc., the shape of the core material assembled on the back side is more likely to be visible on the surface, and the durability and premium feel are easily reduced in the early stages.

[0020] Additionally, for backpacks and other similar items, the straps are often bent in the opposite direction of normal use, i.e., towards the inside, when shipped from the manufacturer. Bending the straps in this opposite direction causes wrinkles, sometimes diminishing their perceived quality during the sales process.

[0021] In addition, during normal use, the cover will bend inwards towards the surface during repeated opening and closing. This prolonged and repeated bending can cause wrinkles on the surface of the strap and cover that are difficult to restore to their original shape, and sometimes the premium feel cannot be maintained.

[0022] The purpose of this invention is to provide a surface material that is not prone to wrinkling, or that is easy to recover even if wrinkles occur on the surface, and that has a lasting premium feel, as well as a backpack using the surface material.

[0023] Problem Solving Methods

[0024] The inventors conducted various studies and discovered that by establishing a specific relationship between the bending hysteresis moment 2HB when bending in the direction inwards from the surface and the thickness h, the aforementioned problem can be solved, thus completing the present invention. That is, the present invention includes the following invention.

[0025] [1] A skin material, wherein the bending hysteresis moment 2HB (gf·cm / cm) and thickness h (mm) when bent in the surface direction satisfy the following equations (I) and (II):

[0026] 2HB≤15h-10(I)

[0027] 1.0≤h≤2.5(II).

[0028] [2] The outer material according to [1] is selected from one or more of the straps and the cover.

[0029] [3] The skin material described in [1] or [2] above has an embossed surface, wherein the maximum height difference between the protrusions and concave parts of the embossed surface is less than 120 μm.

[0030] [4] The skin material described in [1] or [2] above has an arithmetic mean roughness of less than 10 μm.

[0031] [5] The skin material described in [1] or [2] above is disposed on the outer surface side.

[0032] [6] The outer material described in [1] or [2] above is used for school bags.

[0033] [7] A backpack that uses the outer material described in [1] or [2] above.

[0034] The effects of the invention

[0035] According to the present invention, a skin material that is not prone to wrinkling, or that is easy to recover even if wrinkles occur, and that has a lasting premium feel, and a backpack using the skin material can be provided. Detailed Implementation

[0036] Hereinafter, the outer skin material of the embodiments of the present invention and the backpack using the outer skin material of the embodiments of the present invention (hereinafter sometimes referred to as "the outer skin material of this embodiment" or "the backpack using the outer skin material of this embodiment") will be described.

[0037] Preferred embodiments are shown in this specification, and combinations of two or more preferred embodiments are also preferred. Regarding matters expressed as numerical ranges, when several numerical ranges exist, their lower and upper limits can be selectively combined to determine a preferred embodiment.

[0038] It should be noted that in this specification, when the numerical range is described as "XX~YY", it means "above XX and below YY".

[0039] In this specification, when stretching the skin material, the direction with the least extensibility is the "longitudinal direction" of the skin material, and the direction orthogonal to this direction is the "transverse direction" of the skin material.

[0040] In this specification, "cover" means "cover" or "cover plate," referring to the cover-like component that covers the entire opening of the package.

[0041] [Outer Skin Material]

[0042] In this embodiment, the skin material satisfies the following equations (I) and (II) at least in terms of the bending hysteresis moment 2HB (unit: gf·cm / cm, sometimes simply referred to as 2HB) when bent in the surface direction. Furthermore, the bending hysteresis moment 2HB when bent in the opposite direction to the surface direction preferably also satisfies the following equations (I) and (II).

[0043] 2HB≤15h-10(I)

[0044] 1.0≤h≤2.5(II)

[0045] It should be noted that in this specification, "thickness" refers to the value measured under a pressure of 23.5 kPa in accordance with JIS L1096:2020.

[0046] In addition, in the above equations (I) and (II), the units have been removed from the values ​​of bending hysteresis moment 2HB and thickness h.

[0047] In this specification, when a component containing skin material is formed of multiple layers, with inner layers having a hardness difference exceeding 30 from the outermost layer, the outermost layer is considered the skin material. In this case, the bending hysteresis moment 2HB when bent towards the surface is measured using only the outermost layer (the layer peeled from the inside), and the thickness of the skin material refers to the thickness of the outermost layer.

[0048] It should be noted that in this specification, "hardness difference" refers to the difference in hardness, which is the median value obtained by measuring five points with a Type C hardness tester as specified in "7. Hardness Test" of JIS K7312:1996. It should also be noted that the hardness is measured on a smooth and sufficiently hard platform (with a measured value of 80 or higher using a Type D hardness tester as specified in "7. Hardness Test" of JIS K7312:1996), using the surface side of the component as the measurement surface. When the thickness of the test object is less than 10 mm, multiple test objects are stacked to a thickness of 10 mm or more, with the measurement surfaces aligned in the same direction, before measurement.

[0049] In this specification, when a component containing a skin material is formed of multiple layers, with an inner layer having a hardness difference of 30 or less from the outermost layer, and the outermost layer is peeled from the inner layer with a peel strength of 35 N / 25 mm or less, the outermost layer is considered the skin material. In this case, the bending hysteresis moment 2HB when bending towards the surface is measured using only the outermost layer (the layer peeled from the inner side), and the thickness of the skin material refers to the thickness of the outermost layer.

[0050] In this specification, when a component containing a skin material is formed of multiple layers, with an inner layer having a hardness difference of 30 or less from the outermost layer, and the outermost layer cannot be peeled from the inner layer with a peel strength of 35 N / 25 mm or less, the material comprising the outermost and inner layers is considered the skin material. In this case, the bending hysteresis moment 2HB when bending towards the surface is measured using the skin material comprising the outermost and inner layers (without peeling the inner layer), and the thickness of the skin material refers to the skin material comprising the outermost and inner layers.

[0051] When the outermost layer cannot be peeled from the inner layer with a peel strength of less than 35 N / 25 mm, interlayer shift is less likely to occur at the interface between the outermost and inner layers, and the outermost layer can be easily bent as a whole during repeated bending. Therefore, when repeatedly bent in the direction that the outer skin material becomes the inner side, wrinkles are less likely to form on the surface. Moreover, the bending resilience of the outer skin material is not impaired, and it will not adversely affect the performance of the component using the outer skin material.

[0052] It should be noted that the inner layer mentioned above can be a single layer or multiple layers.

[0053] Skin materials that satisfy the above formulas (I) and (II) not only inhibit the occurrence of buckling and are not prone to wrinkles, or even if wrinkles occur, they are easy to restore their original shape, but also have a lasting sense of luxury.

[0054] The skin material in this embodiment is not particularly limited as long as it satisfies the above formulas (I) and (II). From the viewpoint of obtaining a skin material that is not prone to wrinkling, or that easily recovers its original shape even if wrinkles occur, and that maintains a high-end feel, it is preferable to include a woven fabric or a nonwoven fabric as the fiber substrate, and more preferably to include a nonwoven fabric as the fiber substrate. In addition, from the same viewpoint, the skin material in this embodiment preferably has a covering layer on its surface.

[0055] The hysteresis moment 2HB can be adjusted, for example, by changing the type, modulus, and content of the fibers in the fiber matrix of the skin material, the type of resin constituting the polymer elastomer, and the ratio of fibers to polymer elastomers. For instance, by using ultrafine fibers or hollow fibers as fibers, the bending stress of the fibers is reduced, thus lowering the hysteresis moment 2HB. Alternatively, by increasing the ratio of polymer elastomers, the resilience of the skin material is improved, which can also reduce the hysteresis moment 2HB.

[0056] From the viewpoint of suppressing the formation of wrinkles, the 2HB (gf·cm / cm) of the epidermal material in this embodiment is preferably 4.0 gf·cm / cm or more, more preferably 4.5 gf·cm / cm or more, and even more preferably 5.0 gf·cm / cm or more. From the viewpoint of restoring wrinkles even when wrinkles occur and maintaining a high-end feel, it is preferably 18.0 gf·cm / cm or less, more preferably 16.0 gf·cm / cm or less, and even more preferably 14.0 gf·cm / cm or less.

[0057] From the viewpoint of giving a sense of luxury, the thickness h (mm) of the skin material in this embodiment is preferably 1.1 mm or more, more preferably 1.2 mm or more, and even more preferably 1.3 mm or more. From the viewpoint of suppressing the formation of wrinkles, it is preferably 2.3 mm or less, more preferably 2.1 mm or less, and even more preferably 2.0 mm or less.

[0058] From the perspective of lightweight design, the apparent density of the skin material in this embodiment is preferably 0.50 g / cm³. 3 The following is more preferably 0.40 g / cm³. 3 The following is a further preferred value: 0.35 g / cm³ 3 From the perspectives of tensile strength, tear strength, seam strength, and shape retention, 0.25 g / cm³ is preferred. 3 The above, more preferably 0.30 g / cm 3 The above is further preferred to be 0.32 g / cm³. 3 above.

[0059] Apparent density was determined by collecting two 10cm × 10cm test pieces, measuring their respective masses using an electronic balance, and then converting the result to density per cubic meter (m³). 2 The quality is a value calculated based on its average value and the thickness of the test piece.

[0060] The skin material of this embodiment can be embossed. That is, the skin material of this embodiment can have an embossed surface with both recesses and convexities.

[0061] In the case where the skin material of this embodiment has an embossed surface, from the viewpoint of giving a high-end feel, the maximum height difference between the convex and concave parts of the skin material surface is preferably small, which can be less than 120 μm, less than 60 μm, or less than 20 μm. From the viewpoint of ease of manufacturing, it can be more than 5 μm, more than 10 μm, or more than 15 μm.

[0062] It should be noted that the "maximum height difference between the convex and concave parts" of the surface of the skin material in this invention refers to the average value of the maximum height (Rz) obtained by using a Keyence VR-3000 3D surface shape measuring instrument at a magnification of 40x to measure three randomly selected parts on the surface of the skin material, and then filtering the measured values ​​under the condition of no low-pass filter (S-filter) and 1mm high-pass filter (L-filter).

[0063] From the perspective of giving a sense of luxury, the arithmetic mean roughness (Sa) of the surface of the skin material is preferably small, which can be less than 10μm, less than 7μm, or less than 3μm. From the perspective of ease of manufacturing, it can be greater than 0.5μm, greater than 1μm, or greater than 2μm.

[0064] It should be noted that the "arithmetic mean roughness (Sa)" in this invention refers to the average value of the arithmetic mean roughness (Sa) obtained by measuring three randomly selected parts on the surface of the skin material using a VR-3000 3D surface shape measuring instrument manufactured by Keyence at a magnification of 40x, and then filtering the measured values ​​without a low-pass filter (S-filter) and a high-pass filter (L-filter) of 1 mm.

[0065] In this embodiment, the skin material preferably has a bending stiffness as a sheet material covering the outer surface, preferably with a Gurley bending resilience of 2.5 to 25 mN on both the surface and the back, and more preferably with either the surface or the back having 10 mN or more.

[0066] By possessing the bending stiffness of a sheet material used to cover the outer surface, it is possible to create a skin material that is less prone to wrinkles, or that is easier to restore to its original shape even if wrinkles occur, resulting in a more durable and premium feel.

[0067] It should be noted that in this specification, "Gurley flexural resilience" refers to the value measured according to the flexural resilience method A of JIS L1096:2020, 8.22.

[0068] <Fiber substrate>

[0069] As for the fibers constituting the woven fabric or nonwoven fabric that form the fiber substrate, any fiber among conventionally known natural fibers, synthetic fibers, and semi-synthetic fibers can be used, as long as the skin material satisfying formulas (I) and (II) above can be obtained. Considering factors such as quality stability and price, it is preferable to use industrially known cellulose fibers, acrylic fibers, polyester fibers, polyamide fibers, and polyolefin fibers, either alone or in combination. Among these, polyester fibers, polyamide fibers, and polyolefin fibers are preferred, and polyamide fibers are more preferred. In addition, recycled resins and bio-resins can also be used as raw materials for the fibers.

[0070] Examples of polyamide resins constituting polyamide fibers include polyamide 6, polyamide 6,6, polyamide 6,10, polyamide 10,10, polyamide 11, and polyamide 12. Among these, polyamide 6 and polyamide 6,6 are preferred from the viewpoint of ease of acquisition, and polyamide 6 is more preferred.

[0071] The above-mentioned polyamide resins can be used alone or in combination with two or more.

[0072] Without impairing the effects of the present invention, the above-mentioned polyamide resin may contain various additives. Examples of additives include: catalysts, colorants, heat resistant agents, flame retardants, lubricants, antifouling agents, fluorescent whitening agents, matting agents, gloss modifiers, antistatic agents, fragrances, deodorizers, antibacterial agents, anti-mite agents, inorganic microparticles, etc.

[0073] From the viewpoint of obtaining a skin material that is not prone to wrinkles, or that easily recovers its original shape even if wrinkles occur, and that maintains a high-end feel, the fiber length of the fibers contained in the fiber substrate is preferably 30 mm or more, more preferably 35 mm or more, even more preferably 40 mm or more, preferably 70 mm or less, more preferably 65 mm or less, and even more preferably 60 mm or less.

[0074] From the viewpoint of obtaining a surface material that is not prone to wrinkling, or that easily recovers its original shape even if wrinkles occur, and that maintains a high-end feel, the fibers constituting the fiber substrate are preferably ultra-fine fibers or porous hollow fibers, and more preferably ultra-fine fibers.

[0075] In this specification, "microfiber" refers to a fiber that is made extremely fine by removing at least one component from a multi-component fiber (composite fiber) formed from at least two spinnable polymers with different chemical or physical properties.

[0076] In this invention, there are no particular limitations, but it is preferred to use ultrafine fibers that can achieve a soft feel closer to that of natural leather, with an average fineness of 0.3 dtex or less, especially 0.1 dtex or less. In addition, it is preferred to use ultrafine fibers or ultrafine fiber bundles with an average fineness of 0.0001 dtex or more, especially 0.001 dtex or more.

[0077] The skin material of this embodiment can be a combination of two or more fiber substrates with different fiber types, fiber lengths and average fineness, or it can be a single type.

[0078] When the component containing the skin material is formed by a single layer, from the viewpoint of giving a high-end feel, the thickness of the fiber substrate contained in the skin material is preferably 1.0 mm or more, more preferably 1.1 mm or more, and even more preferably 1.2 mm or more. From the viewpoint of suppressing wrinkle formation, it is preferably 2.5 mm or less, more preferably 2.3 mm or less, and even more preferably 2.1 mm or less.

[0079] When a component containing a skin material is formed in multiple layers, with an inner layer having a hardness difference of 30 or less from the outermost layer, and the outermost layer cannot be peeled from the inner layer with a peel strength of 35 N / 25 mm or less, from the viewpoint of imparting a premium feel, the total thickness of the fiber substrate contained in the outermost and inner layers is preferably 1.0 mm or more, more preferably 1.1 mm or more, and even more preferably 1.2 mm or more. From the viewpoint of suppressing wrinkle formation, it is preferably 2.5 mm or less, more preferably 2.3 mm or less, and even more preferably 2.1 mm or less.

[0080] <Polymer Elastomers>

[0081] From the perspective of providing a premium feel, a texture close to that of natural leather, and shape stability, the surface material of this embodiment preferably contains a polymer elastomer.

[0082] For the skin material of this embodiment, the fiber substrate contained in the skin material may contain a polymer elastomer, the coating layer formed on the surface of the skin material may contain a polymer elastomer, or the fiber substrate contained in the skin material may contain a polymer elastomer and the coating layer formed on the surface of the skin material may contain a polymer elastomer.

[0083] The polymeric elastomer contained in the fiber substrate, which is included as the outer material, can be any known polymeric elastomer commonly used in the manufacture of artificial leather. Examples include: polyurethane resins, polyester elastomers, rubber resins, polyvinyl chloride resins, polyacrylic acid resins, polyamino acid resins, silicone resins, and their modifiers, copolymers, or mixtures. The polymeric elastomer can be contained in the fiber substrate alone or in two or more forms.

[0084] From the perspective of giving the skin material a high-end feel, the fiber substrate contained in the skin material preferably contains polyurethane resin as a polymer elastomer.

[0085] Examples of polyurethane resins include various polyurethanes obtained by reacting the following substances in a given molar ratio: at least one selected from polymeric diols such as polyester glycol, polyether glycol, polyester ether glycol, polylactone glycol, and polycarbonate glycol, with an average molecular weight of 500 to 3000; at least one selected from organic diisocyanates such as toluene diisocyanate, phenyl dimethyl diisocyanate, phenyl diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate, which are aromatic, alicyclic, or aliphatic organic diisocyanates; and at least one chain extender selected from diols such as ethylene glycol, diamines, hydroxylamines, hydrazides, and acylhydrazides, which are low molecular weight compounds having at least two active hydrogen atoms. Polyurethanes obtained by reacting at least one selected from polymeric diols such as polyester glycol, polyether glycol, and polycarbonate glycol are preferred. In addition, polyurethane raw materials can also include diols made from biological raw materials, diols made from carbon dioxide, and diols obtained from chemical recycling.

[0086] The fiber substrate contained in the skin material may contain one type of polyurethane or two or more types of polyurethane as a polymer elastomer. In addition, it may also contain synthetic rubber, polyester elastomer, polyvinyl chloride, etc.

[0087] To adjust the physical properties and feel, the mass ratio of the fiber substrate to the polymer elastomer contained in the outer material can be appropriately selected, without particular limitation. For example, when the outer material of the present invention is used as a backpack strap, the mass ratio of the fiber substrate to the polymer elastomer (fiber substrate / polymer elastomer) is preferably 80 / 20 to 20 / 80, more preferably 70 / 30 to 30 / 70, and even more preferably 60 / 40 to 40 / 60.

[0088] When the fiber substrate contains a polymeric elastomer, it is preferable that the polymeric elastomer exists in a solidified, sponge-like state. Furthermore, it is preferable that the fiber substrate has a porous layer formed from the solidified, sponge-like polymeric elastomer.

[0089] The fiber substrate, with its porous layer formed by a polymer elastomer solidified into a sponge-like structure, easily produces a surface material that has a feel similar to natural leather, is not prone to wrinkling, or easily recovers its original shape even if wrinkles occur, and has a lasting premium feel.

[0090] From the viewpoint of providing a feel similar to natural leather, and from the viewpoint of obtaining a surface material that is not prone to wrinkling, or that easily recovers its original shape even if wrinkles occur, and has a lasting premium feel, the thickness of the aforementioned porous layer is preferably 100 to 800 μm, more preferably 200 to 600 μm, and even more preferably 300 to 500 μm.

[0091] <Covering layer>

[0092] In this embodiment, the skin material preferably has a coating layer on its surface.

[0093] It should be noted that when the skin material has a multilayer fiber substrate, it is preferable to have a covering layer on the outermost fiber substrate.

[0094] Examples of polymeric elastomers contained in the coating layer formed on the surface of the skin material include synthetic rubber, polyester elastomers, polyvinyl chloride, and polyurethane resins. Among these, polyurethane resins are preferred from the viewpoints of elasticity, softness, abrasion resistance, and the ability to form a porous structure.

[0095] Examples of polyurethane resins include those identical to the polymeric elastomer contained in the fiber substrate of the aforementioned skin material. Alternatively, polyurethanes composed of a mixture of various polyurethanes can be used as needed. Furthermore, polymer compositions primarily composed of polyurethane resins, obtained by adding polymers such as synthetic rubber, polyester elastomers, and polyvinyl chloride, can also be used. Among these, polyurethanes obtained by reacting at least one selected from polymeric diols such as polyester glycol and polyether glycol are preferred.

[0096] The coating layer containing polymeric elastomers may contain one type of polyurethane as the polymeric elastomer, or it may contain two or more types of polyurethane. In addition, it may also contain synthetic rubber polyester elastomers, polyvinyl chloride, etc.

[0097] The coating layer containing polymeric elastomers may include additives such as colorants, lightfastness agents, dispersants, deodorizers, antibacterial agents, and foaming agents. One additive may be used alone, or two or more may be used.

[0098] The coating layer containing the polymer elastomer can be a single layer or two or more layers.

[0099] When the coating layer containing the polymer elastomer consists of two or more layers, each layer may contain the same polymer elastomer or different polymer elastomers.

[0100] From the viewpoint of obtaining a skin material that is not prone to wrinkling, or that easily recovers its original shape even if wrinkles occur, and has a lasting premium feel, the thickness of the coating layer containing the polymer elastomer is preferably 1 μm or more, more preferably 3 μm or more, and even more preferably 5 μm or more. From the viewpoint of suppressing wrinkle formation, it is preferably 300 μm or less, more preferably 250 μm or less, and even more preferably 230 μm or less.

[0101] It should be noted that when the coating layer containing polymer elastomer has two or more layers, the thickness refers to the total thickness.

[0102] The content of polymer elastomer in the coating layer containing polymer elastomer is preferably 30% by mass or more, more preferably 40% by mass or more, even more preferably 50% by mass or more, and can be 100% by mass.

[0103] When a coating layer containing a polymeric elastomer is formed on the surface of a skin material, the skin material may have an adhesive layer between the coating layer and the fiber substrate for bonding the coating layer and the fiber substrate.

[0104] From the viewpoint of adhesion and flexibility, polyurethane adhesives, acrylic adhesives, and melamine adhesives are preferred as the adhesives constituting the adhesive layer, and polyurethane adhesives are more preferred.

[0105] From the viewpoint of adhesion, the thickness of the adhesive layer is preferably 10 μm or more, more preferably 20 μm or more, and even more preferably 30 μm or more. From the viewpoint of imparting a sense of sophistication, it is preferably 100 μm or less, more preferably 90 μm or less, and even more preferably 80 μm or less.

[0106] When a coating layer containing a polymeric elastomer is formed on the surface of a skin material, the coating layer can be bonded to the fiber substrate by impregnating the fiber substrate with an adhesive. That is, the fiber substrate may contain an adhesive. Examples of adhesives impregnated in the fiber substrate include adhesives similar to those constituting the adhesive layer described above.

[0107] When a coating layer containing a polymeric elastomer is formed on the surface of a skin material, the polymeric elastomer can be in a sponge-like state. Alternatively, the coating layer can have a porous layer formed from the sponge-like polymeric elastomer.

[0108] The covering layer, having a porous layer formed by a polymer elastomer solidified into a sponge-like structure, easily achieves a feel similar to natural leather.

[0109] <Other Ingredients>

[0110] The skin material of this embodiment may or may not contain components other than the fiber matrix and the polymer elastomer. Examples of such other components include additives similar to those contained in the polyamide resin and the additives contained in the coating layer containing the polymer elastomer. These other components may be encapsulated within at least one of the fiber matrix and the polymer elastomer.

[0111] From the viewpoint that the desired effects brought about by the other components mentioned above are easily manifested, as well as the water absorption, water resistance, and stain resistance, the content of the other components mentioned above in the skin material is preferably 0 to 10% by mass, more preferably 0 to 5% by mass, and even more preferably 0 to 2% by mass.

[0112] <Uses of Skin Materials>

[0113] The outer material of this embodiment is not prone to wrinkling on the surface, or even if wrinkles do occur, it is easy to restore its original shape and has a lasting premium feel. Therefore, it can be used not only for bags, but also for various other applications such as shoes, clothing, balls, furniture such as sofas, and car seats.

[0114] The outer material of this embodiment can be suitably used in backpacks, such as school bags, backpacks, small backpacks, shoulder bags, everyday bags, school bags, shoulder bags, waist bags, and hip bags. It is particularly suitable for school bags. When using the outer material in a school bag, it is preferable to use it on the shoulder straps and flaps, where wrinkles can easily diminish the perceived quality; more preferably, it is placed on the outer surface that does not directly contact the body.

[0115] [Manufacturing method of skin material]

[0116] From the viewpoint of obtaining a skin material that is not prone to wrinkling, or that easily recovers its original shape even if wrinkles occur, and that maintains a high-end feel, the skin material of this embodiment is preferably manufactured by a manufacturing method comprising the following steps (1A) to (4A) (first embodiment), or a manufacturing method comprising the following steps (1B) to (4B) (second embodiment). Furthermore, the first embodiment and the second embodiment may further include the following step (5), or may not include it.

[0117] <First Implementation>

[0118] Process (1A): The process of preparing a fiber web formed from ultrafine fiber-generating fibers.

[0119] Step (2): The process of obtaining the cohesive nonwoven fabric using the above-mentioned fiber web.

[0120] Step (3): The process of impregnating the above-mentioned polymeric elastomer into the above-mentioned cohesive nonwoven fabric.

[0121] Process (4A): The process of removing sea components from the above-mentioned ultrafine fiber-producing fibers.

[0122] Step (5): Step of forming a coating layer containing a polymer elastomer

[0123] <Second Implementation Method>

[0124] Process (1B): The process of preparing a fiber web formed from hollow fiber-generating fibers.

[0125] Step (2): The process of obtaining the cohesive nonwoven fabric using the above-mentioned fiber web.

[0126] Step (3): The process of impregnating the above-mentioned polymeric elastomer into the above-mentioned cohesive nonwoven fabric.

[0127] Process (4B): The process of removing island components from the hollow fiber producing type fiber described above.

[0128] Step (5): Step of forming a coating layer containing a polymer elastomer

[0129] The following is a description of each process.

[0130] <Process (1A)>

[0131] Process (1A) is the process of preparing a fiber web formed from ultrafine fiber-generating fibers.

[0132] As described above, ultrafine fibers refer to fibers that are made extremely fine by removing at least one component from multi-component fibers (composite fibers) formed from at least two or more spinnable polymers with different chemical or physical properties. Multi-component fibers that can produce such ultrafine fibers are ultrafine fiber producing fibers. Representative examples of ultrafine fiber producing fibers include island-type composite fibers, multi-layered composite fibers, and radially layered composite fibers obtained by methods such as chip blending (mixed spinning) and composite spinning. Among these, from the viewpoint that high-speed spinning can improve productivity and further obtain artificial leather with excellent surface abrasion resistance and pilling resistance, island-type composite fibers are preferred. From the same viewpoint, melt spinning of island-type composite fibers to obtain a fiber web is preferred.

[0133] When the ultrafine fiber producing type fiber is an island-type composite fiber, the island component is dispersed in the sea component, which serves as the matrix, in the fiber cross section, and fiber bundles of ultrafine fibers are produced by removing the sea component.

[0134] The following describes in more detail the method of using island-type composite fibers as the type of ultrafine fiber production fibers and obtaining a fiber web by melt spinning the island-type composite fibers.

[0135] The resin that forms the island component of the island-type composite fiber, which subsequently becomes an ultrafine fiber, can be the same resin as the polyamide resin that constitutes polyamide fibers.

[0136] For the resin containing marine components that can be removed through extraction or decomposition in island-type composite fibers, it is preferable to use a resin with different solubility or decomposability and low compatibility with the resin containing the island components. Such a resin is preferably selected appropriately based on the type and manufacturing method of the resin containing the island components.

[0137] Examples of resins that can be used as marine components include olefin resins such as polyethylene, polypropylene, ethylene-propylene copolymer, and ethylene-vinyl acetate copolymer, as well as polystyrene, styrene-acrylic acid copolymer, and styrene-ethylene copolymer, which are soluble in organic solvents and can be removed using organic solvents. Additionally, examples include polyvinyl alcohol resins, water-soluble polyester resins, modified polyester resins that are easily decomposed by alkalis, polyacrylamide resins, and carboxymethyl cellulose resins, which can be removed using only water without the need for solvents. From the viewpoint of melt spinning properties, polyethylene and polystyrene are preferred.

[0138] The mass ratio of sea component to island component in island-type composite fibers is not particularly limited, but a range of 5:95 to 80:20 is preferred. When the polymer content of sea component in the island-type composite fiber is 5% by mass or more, the spinning stability of the island-type fiber is less likely to decrease, making it easier to ensure industrial production. Furthermore, when a polymer elastomer is incorporated, the removal of the sea component facilitates the formation of gaps of the desired size between the ultrafine fiber bundles and the polymer elastomer, resulting in a more easily obtained sense of fullness, density, and compactness. On the other hand, when the polymer content of sea component is 60% by mass or less, the shape and distribution of the island component in the cross-section of the island-type fiber are stable, making it easier to prevent a decrease in quality stability.

[0139] As a method for manufacturing fiber webs, conventionally known methods such as carding, papermaking, and spunbonding can be used.

[0140] In this embodiment, preferably after melt spinning, the obtained fibers are stretched to approximately 1-5 times their original length, then crimped, and cut into short fibers of approximately 30-70 mm in length. These fibers are then unbound using a carding machine and passed through a web forming machine. This results in a fiber web with the desired density.

[0141] <Process (1B)>

[0142] Process (1B) is the process of preparing a fiber web formed from hollow fiber-generating fibers.

[0143] Representative examples of hollow fiber-producing fibers include island-type composite fibers, multilayer composite fibers, and radially layered composite fibers obtained by methods such as chip blending (mixed spinning) and composite spinning. Among these, island-type composite fibers are preferred.

[0144] When the hollow fiber producing type fiber is an island-type composite fiber, the island component is dispersed in the sea component that serves as the matrix in the fiber cross section. When the island component is removed, the sea component remains, resulting in a porous hollow fiber with a large number of hollow parts in the fiber.

[0145] The resin that forms the sea component in island-type composite fibers and subsequently becomes porous hollow fibers can be the same resin that constitutes polyamide fibers.

[0146] As a resin containing island components that can be removed through extraction, decomposition, etc., in island-type composite fibers, examples include resins that are the same as the resin containing sea components in step (1A), and preferably the same.

[0147] There is no particular limitation on the mass ratio of sea component to island component in island-type composite fibers. From the viewpoint of cross-section formation, it is preferably 10 / 90 to 60 / 40, and more preferably 20 / 80 to 60 / 40.

[0148] As a method for manufacturing fiber webs, conventionally known methods such as carding, papermaking, and spunbonding can be used.

[0149] In this embodiment, it is preferable that after melt spinning, the obtained fibers are stretched to about 1 to 5 times their original length, then crimped, and the fiber length is cut into about 3 to 7 cm to make short fibers. After that, the fibers are de-fired by a carding machine and then passed through a web forming machine to obtain a fiber web with the desired density.

[0150] <Process (2)>

[0151] Step (2) is the process of obtaining a cohesive nonwoven fabric using the above-mentioned fiber web.

[0152] In process (2), the fiber web is laminated in multiple layers using a cross-laying machine or the like as needed to form a fiber web laminate, and then a cohesion process is performed to obtain a cohesive nonwoven fabric.

[0153] As a cohesive treatment, examples include needle piercing or high-pressure water jet treatment under the condition that at least one hook penetrates from both sides simultaneously or alternately.

[0154] When performing cohesion treatment by needle punching, various treatment conditions can be appropriately selected, such as the type of needle (needle shape, needle size, hook shape, depth, number of hooks, position, etc.), needle punching density (the needle punching density per unit area obtained by multiplying the density of the number of needles planted per unit area of ​​the needle plate by the number of reciprocating strokes of the needle group into the fiber web per unit area), and needle punching depth (the depth to which the needle group penetrates the fiber web).

[0155] Furthermore, regarding the needle-punching density, from the viewpoint that high abrasion resistance can be easily obtained by balancing the cohesion state and fiber density, a needle density of 300 to 4000 needles / cm is preferred. 2 The needle density was 300 needles / cm². 2 At the above stage, the fibers, bent towards the thickness direction due to the hooks, approach each other, thereby accelerating cohesion, increasing fiber density, and achieving a sufficient cohesion state. Additionally, the needle-punching density is 4000 needles / cm². 2 In the following cases, the cutting of fibers caused by hooking, which is prone to occur due to excessively high fiber density, is suppressed, and the tendency for the fiber web surface to deteriorate and become cohesive is particularly difficult to occur.

[0156] Furthermore, oiling agents and antistatic agents can be applied to ultrafine fiber-generating fibers, hollow fiber-generating fibers, fiber webs, fiber web laminates, and cohesive nonwoven fabrics at any stage from melt spinning of island-type composite fibers to cohesion treatment. Additionally, the cohesion can be pre-dense by immersing the ultrafine fiber-generating fibers, hollow fiber-generating fibers, fiber webs, fiber web laminates, and cohesive nonwoven fabrics in warm water at approximately 70-150°C for shrinkage treatment, as needed.

[0157] The preferred unit area weight of the cohesive fiber sheet is 100~1000 g / m². 2 The range is approximately 60-60 degrees. Furthermore, the fiber density and cohesion can be further increased by heat shrinking the cohesive fiber sheet as needed. Additionally, hot pressing can be performed as needed to further densify the cohesive fiber sheet after heat shrinking, to fix the shape of the cohesive fiber sheet, and to smooth the surface.

[0158] In addition, the cohesive nonwoven fabric can be sanded to smooth the surface.

[0159] <Process (3)>

[0160] Step (3) is the process of impregnating the above-mentioned polymer elastomer into the above-mentioned cohesive nonwoven fabric.

[0161] As a method of impregnation, known methods such as impregnation clamping, doctor blade coating, bar coating, roller coating, and spraying can be used to impregnate the polymer elastomer alone or in combination with a solution or dispersion containing the polymer elastomer.

[0162] Details of the polymer elastomer used in process (3) are as described in the “Polymer Elastomer” section above.

[0163] The content of polymeric elastomer in the solution or dispersion containing polymeric elastomer is preferably 10 to 60% by mass.

[0164] In solutions or dispersions containing polymeric elastomers, various additives such as dyes, pigments and other colorants, coagulation regulators, antioxidants, ultraviolet absorbers, fluorescent agents, antifungal agents, penetrants, defoamers, lubricants, water repellents, oil repellents, thickeners, bulking agents, curing accelerators, foaming agents, polyvinyl alcohol, carboxymethyl cellulose, and other water-soluble polymeric compounds can be appropriately added within a range that does not impair the properties of the final skin material.

[0165] Furthermore, when using a dispersion, if a heat-sensitive gelling agent is added beforehand, more uniform solidification in the thickness direction can be achieved through a dry method, or by combining it with methods such as evaporation or far-infrared heating. Additionally, when using a solution, more uniform porosity can be easily obtained by combining it with a coagulation modifier.

[0166] Preferably, after the polymeric elastomer is prepared into a solution or dispersion and impregnated into the cohesive nonwoven fabric, the cohesive elastomer is solidified into a sponge-like structure by means of a wet method when using a solution and by means of a dry method when using an aqueous dispersion, thereby creating a porous layer in the cohesive nonwoven fabric by generating a large number of pores. In this embodiment, the cohesive elastomer is preferably solidified by a wet method.

[0167] By solidifying the polymer elastomer impregnated in the nonwoven fabric into a sponge-like structure, a porous layer is formed, making it easy to obtain a surface material that has a feel similar to natural leather, is not prone to wrinkling, or easily recovers its original shape even if wrinkles occur, and has a lasting premium feel.

[0168] As a method for solidifying polymeric elastomers using a wet method, one example is to immerse the material in a coagulation solution at 20-60°C for 1-60 minutes in a good solvent containing polyurethane such as N,N-dimethylformamide, dimethylacetamide, and N-methylpyrrolidone, and water. From the viewpoint of obtaining a skin material that is not prone to wrinkling, or that easily recovers its original shape even if wrinkles occur, and that maintains a high-end feel, a coagulation solution containing N,N-dimethylformamide and water is preferred. Furthermore, the ratio of N,N-dimethylformamide to water in the coagulation solution (N,N-dimethylformamide:water) is preferably 10:90 to 50:50.

[0169] <Process (4A)>

[0170] Process (4A) is a process for removing marine components from the above-mentioned ultrafine fiber-producing fibers.

[0171] By removing marine components from ultrafine fiber-producing fibers, ultrafine fiber-producing fibers can be transformed into fiber bundles of ultrafine fibers. This allows the acquisition of a fiber substrate containing ultrafine fibers.

[0172] Process (4A) can be performed before or after process (3).

[0173] When process (4A) is performed after process (3), the marine component is removed, creating a gap between the ultrafine fiber bundle and the polymer elastomer. The binding of the ultrafine fiber bundle brought by the polymer elastomer becomes weaker, thus the surface material tends to have a softer feel, which is preferred.

[0174] As a method for removing resin containing marine components, one example is to use a solvent or decomposing agent that can selectively remove only the resin containing marine components.

[0175] When the marine components are water-soluble resins such as polyvinyl alcohol resins, water-soluble polyester resins, modified polyester resins that are easily decomposed by alkali, polyacrylamide resins, and carboxymethyl cellulose resins, the marine components can be removed by water.

[0176] When the marine component is insoluble in water but soluble in organic solvents, and the resin containing the marine component is a polyamide resin or a polyester resin, examples of organic solvents that can dissolve and remove the marine component include toluene, trichloroethylene, and tetrachloroethylene.

[0177] In this embodiment, toluene, which has high resin solubility, is preferably used.

[0178] <Process (4B)>

[0179] Process (4B) is a process for removing island components from the hollow fiber-generating fiber described above.

[0180] By removing island components from hollow fiber-producing fibers, hollow fiber-producing fibers can be transformed into fiber bundles of hollow fibers. This yields a fiber substrate containing hollow fibers.

[0181] Process (4B) can be performed before or after process (3).

[0182] As a method for removing island components from resin, one example is to use a solvent or decomposing agent that can selectively remove only the island components from the resin.

[0183] When the island components are water-soluble resins such as polyvinyl alcohol resin, water-soluble polyester resin, modified polyester resin that is easily decomposed by alkali, polyacrylamide resin, and carboxymethyl cellulose resin, the island components can be removed by water.

[0184] When the island component is insoluble in water but soluble in organic solvents, and the resin for the sea component is a polyamide resin or a polyester resin, examples of organic solvents that can dissolve and remove the island component include toluene, trichloroethylene, and tetrachloroethylene.

[0185] In this embodiment, toluene, which has high resin solubility, is preferably used.

[0186] <Process (5)>

[0187] Step (5) is the process of forming a coating layer containing a polymer elastomer.

[0188] In step (5), it is preferable to form a coating layer containing a polymer elastomer on the fiber substrate.

[0189] Details of the polymer elastomer used in process (5) are as described in the “Polymer Elastomer” section above.

[0190] Examples of methods for forming a coating layer containing a polymeric elastomer on the surface of a fiber substrate include: lamination, which involves forming a resin film on release paper using a solution or dispersion containing a polymeric elastomer, bonding the resin film to the surface of the fiber substrate, and then peeling off the release paper to form the coating layer; and methods that involve coating the surface of the fiber substrate with a solution or dispersion containing a polymeric elastomer using a gravure coating machine, a rod coating machine, a doctor blade coating machine, or a corner-cutting wheel coating machine, and then drying it.

[0191] The coating layer can be molded to form the desired appearance as needed through embossing or other methods.

[0192] In the above-mentioned lamination method, specifically, a solution or dispersion containing a polymer elastomer is coated in a given amount onto a transfer release sheet such as a film or release paper, and dried to a film state or dried / solidified to a porous state to form a resin film. Then, it is bonded to a fiber substrate by an adhesive such as a polyurethane adhesive, or bonded by redissolving using a solution or dispersion containing a polymer elastomer, etc., to make it integrated, and then the release transfer sheet is peeled off.

[0193] When bonding is performed using an adhesive, pressure can be applied as needed using heated rollers (room temperature to 130°C) to bond the resin film while the adhesive has penetrated into the fiber substrate. In this case, the degree of adhesive penetration can be adjusted by regulating the heating temperature. Furthermore, the melt viscosity of the resin constituting the adhesive can be adjusted to change the temperature dependence of softening due to heat, thereby adjusting the degree of adhesive penetration.

[0194] In the method of forming by coating a solution or dispersion containing a polymeric elastomer onto the surface of a fiber substrate and then drying it, the coating can be dried to a film state by dry method or solidified / dried to a porous state by wet method.

[0195] In the solution or dispersion containing a polymeric elastomer used to form the aforementioned resin film, and in the solution or dispersion containing a polymeric elastomer used to coat the surface of a fiber substrate, in addition to the polymeric elastomer, known additives may also be added, such as thickeners, curing accelerators, extenders, fillers, light stabilizers, antioxidants, ultraviolet absorbers, fluorescent agents, mildew inhibitors, flame retardants, penetrants, surfactants, water-soluble polymers such as polyvinyl alcohol and carboxymethyl cellulose, dyes, pigments, adhesives, etc.

[0196] The coating layer containing the polymer elastomer can be formed as a single layer or as two or more layers.

[0197] When the coating layer containing the polymer elastomer consists of two or more layers, the polymer elastomer solution used to form each layer can be the same or contain different components.

[0198] [bag]

[0199] The backpack according to an embodiment of the present invention is a backpack that uses the outer material of an embodiment of the present invention.

[0200] The outer material of the embodiments of the present invention is not prone to wrinkling, or even if wrinkles occur, it is easy to restore its original shape and has a lasting premium feel. Therefore, it can give the backpack a lasting premium feel, especially when used for the shoulder straps and flaps of a backpack.

[0201] [Backpack]

[0202] The backpack of this embodiment uses the outer material of this embodiment. The backpack of this embodiment includes: a box-shaped main body with an opening for allowing items to enter and exit the storage compartment from above or from the top to the upper front during use; and straps or other strap members attached to the main body for securing the backpack to the user's body. It should be noted that, in order to protect the items stored within the intended use area, the main body preferably possesses the strength to maintain the box shape.

[0203] In the front view and top view of the main body in use, the box shape of the main body is preferably a roughly rectangular or square shape, and the rectangle is preferably a shape that is longer in the height direction or the width direction in the front view.

[0204] Regarding the size of the receiving portion of the main body, the length of the short side in the front view is preferably 20-29 cm, more preferably 22-27 cm, and the length of the short side in the top view is preferably 9-18 cm, more preferably 11-16 cm.

[0205] The aforementioned components are installed on any of the top, back, or bottom surfaces of the main body, and the number of components is one or two.

[0206] The backpack of this embodiment may include a cover that can cover the entire opening and can be opened and closed.

[0207] The aforementioned cover can cover the entire aforementioned opening and extends along the front side of the main body, covering more than 1 / 2 of the front side of the main body.

[0208] The surface material of this embodiment is not prone to wrinkling, or even if wrinkles do occur, it easily recovers its original shape and maintains a high-end feel. Therefore, it can be appropriately used as a surface material for strap components such as shoulder straps, covers, and the main body other than the back panel, and is particularly preferred for use as a surface material for strap components such as shoulder straps and covers. In this case, from the viewpoint of exhibiting a high-end feel, the surface material preferably has a leather-like appearance.

[0209] Example

[0210] The present invention will be further described in detail below through embodiments. It should be noted that the scope of the present invention is not limited by the content of the embodiments.

[0211] [Measurement and Evaluation Methods]

[0212] Various physical properties were determined using the following methods. The results are shown in Table 1.

[0213] <Thickness of Polyurethane Porous Layer and Coating Layer>

[0214] Regarding the thickness of the porous layer, the cross-section of the cut epidermal material was measured using an electron microscope at 50x magnification. The thickness of the epidermal layer itself was measured at 100x magnification in the same area. For epidermal layer thicknesses below 10 μm, measurements were taken at 200x magnification.

[0215] <Maximum height difference between convex and concave parts>

[0216] Three randomly selected locations on the surface of the obtained leather material (the side surface of the covering layer) were measured using a Keyence VR-3000 3D surface shape measuring instrument at 40x magnification. The measured values ​​were then filtered without a low-pass filter (S-filter) and with a high-pass filter (L-filter) of 1 mm to obtain the maximum height (Rz). The average of the maximum heights (Rz) of the three locations was calculated as the maximum height difference between the convex and concave parts of the skin material.

[0217] Arithmetic mean roughness

[0218] Three randomly selected locations on the surface of the obtained skin material (coating layer side surface) were measured using a Keyence VR-3000 3D surface shape measuring instrument at 40x magnification. The arithmetic mean roughness was obtained by filtering the measured values ​​without a low-pass filter (S-filter) and with a high-pass filter (L-filter) of 1 mm. The average of the arithmetic mean roughness of the three locations was calculated as the arithmetic mean roughness (Sa) of the skin material.

[0219] <Bending hysteresis moment 2HB>

[0220] Two test pieces were prepared, each 5cm wide and 20cm long, cut from the obtained skin material. One piece was cut with its length aligned with the longitudinal direction of the skin material, serving as the "longitudinal test piece." The other piece was cut with its length aligned with the transverse direction of the skin material, serving as the "transverse test piece." A large bending testing machine, "KES-FB2-L" (Kato-tech), was used at a maximum curvature of ±0.4cm. -1 Under the conditions, the bending hysteresis moment of the longitudinal test piece and the bending hysteresis moment of the transverse test piece were measured once each, and the average value of the measured values ​​of the two test pieces was taken as the bending hysteresis moment 2HB.

[0221] It should be noted that the bending hysteresis moment is calculated based on the surface of the skin material (the surface of the covering layer) with a curvature of 0.2 cm. -1 The value of the bending moment when the bend is concave (bending towards the surface), and the value of the bending moment with a curvature of 0.2 cm. -1 The value of the bending moment is calculated when the bend is convex (bending in the opposite direction to the surface direction) and rounded to one decimal place.

[0222] <Thickness>

[0223] According to the thickness A method of JIS L1096:2020, the thickness (mm) of the skin material is measured at two or more different locations approximately 2-5 cm apart under a pressure of 23.5 kPa. These values ​​are averaged and rounded to one decimal place.

[0224] Apparent density

[0225] Apparent density was calculated as follows: Two 10cm × 10cm test pieces were collected, and their respective masses were measured using an electronic balance and converted to per cubic meter (m³). 2 The quality is calculated based on its average value and the thickness of the test piece.

[0226] <Evaluation of the folds>

[0227] The obtained skin material was cut into test pieces with a length of 6 cm and a width of 2 cm in a manner where the longitudinal direction of the skin material was aligned with the length direction. The test pieces were folded in half at the central part in the length direction such that the side surface of the coating layer became concave, a 500 g weight was placed, and it was left standing for 5 minutes. Then, the weight was removed, and after 24 hours, the test pieces were visually observed, and the state of the wrinkles was judged according to the following criteria.

[0228] A: No wrinkles that can be confirmed by the naked eye were generated.

[0229] B: At least one wrinkle that can be confirmed by the naked eye was generated, but the wrinkle was not conspicuous and did not impair the high-class feeling.

[0230] C: At least one wrinkle that can be seen by the naked eye was generated, and due to the conspicuousness of the wrinkle, the high-class feeling was impaired.

[0231] It should be noted that for the skin material with the above evaluation result being good, when used as a strap or a lid part of a schoolbag, etc., it can be considered as a material that is not likely to generate wrinkles, or even if wrinkles are generated, it is easy to return to its original state, and the high-class feeling lasts.

[0232] <Gurley bending resilience>

[0233] Ten test pieces with a length of 38 mm and a width of 25 mm were cut from the obtained skin material in a manner where the length direction of the test pieces was aligned with the longitudinal direction of the skin material, and used as "longitudinal test pieces". In addition, ten test pieces with a length of 38 mm and a width of 25 mm were cut from the obtained skin material in a manner where the length direction of the test pieces was aligned with the transverse direction of the skin material, and used as "transverse test pieces".

[0234] Using the obtained "longitudinal test pieces" and "transverse test pieces", the Gurley bending resilience was measured according to the bending resilience A method of JIS L1096:020. It should be noted that among the "longitudinal test pieces", the Gurley bending resilience of the coating layer side of the skin material was measured for 5 pieces, and the average value was used as the "longitudinal Gurley bending resilience on the front side", and for the remaining 5 pieces, the Gurley bending resilience of the side opposite to the coating layer side of the skin material was measured, and the average value was used as the "longitudinal Gurley bending resilience on the back side". In addition, among the "transverse test pieces", the Gurley bending resilience of the coating layer side of the skin material was measured for 5 pieces, and the average value was used as the "transverse Gurley bending resilience on the front side", and for the remaining 5 pieces, the Gurley bending resilience of the side opposite to the coating layer side of the skin material was measured, and the average value was used as the "transverse Gurley bending resilience on the back side".

[0235] [Example 1]

[0236] A 15 dtex island-type composite fiber was produced by melt spinning 50 parts by weight of polyethylene (island component) and 50 parts by weight of polyamide 6 (island component) in the same melt system. This island-type composite fiber was stretched to 2.5 times its original length, crimped, and then cut into fibers of 51 mm in length. The resulting short fibers were opened using a carding machine and formed into a fiber web through a cross-laying mechanism. The fiber webs were then stacked, needle-punched, heated to 120°C, and pressed through calendering rollers to produce a fiber with a thickness of 2.3 mm and a basis weight of 600 g / m². 2 A smooth, cohesive nonwoven fabric.

[0237] Next, the nonwoven fabric is impregnated with a dimethylformamide (DMF) solution containing 15% by mass of a polyester polyurethane (1), thereby impregnating the polyester polyurethane (1) in the nonwoven fabric. The polyester polyurethane (1) is a mixture of polyester polyurethane (A) and polyether polyurethane (B) in a mass ratio of (A):(B)=8:2. The polyester polyurethane (A) is obtained by polymerizing polyethylene adipate (PEA), 4,4'-diphenylmethane diisocyanate (MDI) and ethylene glycol (EG), and the polyether polyurethane (B) is obtained by polymerizing polyethylene glycol (PEG), MDI and EG.

[0238] Then immediately add a 25% by mass DMF solution of polyester polyurethane (2) obtained by polymerizing PEA, MDI and EG at 150 g / m 2 The polyester polyurethane (2) is applied to the surface of the nonwoven fabric to impregnate the nonwoven fabric.

[0239] Next, a DMF solution containing 20% ​​by mass of polycarbonate-based polyurethane (100% modulus: 4 MPa) was added at 370 g / m³. 2 The polycarbonate polyurethane, coated onto the surface of the nonwoven fabric, is obtained by polymerizing a polymeric diol containing polyhexamethylene carbonate diol (PHC) as the main component (containing more than 50% by mass), a diisocyanate containing MDI as the main component (containing more than 50% by mass), and a chain extender containing EG as the main component (containing more than 50% by mass).

[0240] The obtained cohesive nonwoven fabric was immersed in a coagulation solution of DMF / water = 20 / 80 for 30 minutes to wet coagulate the polycarbonate polyurethane into a porous structure.

[0241] Next, after washing, polyethylene in the island-type composite fiber was removed by toluene extraction and transformed into ultrafine fibers formed from polyamide 6 with an average fineness of 0.01 dtex. This resulted in a fiber substrate with a thickness of 1.6 mm in which a polyurethane porous layer was formed on the nonwoven fabric formed by the fiber bundles of ultrafine polyamide 6.

[0242] A DMF solution is applied to the surface of the fiber substrate using a 200-mesh gravure roller and dried to form a coating layer approximately 5 μm thick as a non-porous layer, thus obtaining the skin material. The DMF solution contains, relative to 100 parts by mass of DMF, 15 parts by mass of a polyester polyurethane obtained by polymerizing PEA, MDI, and EG, 3 parts by mass of a yellow pigment, and 1 part by mass of titanium dioxide. It should be noted that the combined thickness of the polyurethane porous layer and the non-porous layer (coating layer) is approximately 200 μm.

[0243] [Example 2]

[0244] A 10 dtex island-type composite fiber was produced by melt spinning 50 parts by weight of polyethylene (island component) and 50 parts by weight of polyamide 6 (island component) in the same melt system. This island-type composite fiber was stretched to 2.5 times its original length, crimped, and then cut into fibers of 51 mm in length. The resulting short fibers were opened using a carding machine and formed into a fiber web through a cross-laying machine. The fiber webs were then stacked, needle-punched, heated to 120°C, and pressed through calendering rollers to produce a fiber with a thickness of 1.9 mm and a basis weight of 540 g / m². 2 The surface is smooth and the nonwoven fabric is cohesive.

[0245] Next, the nonwoven fabric is impregnated with a DMF solution containing 20% ​​polyether polyurethane, and then impregnated with a coagulation solution of DMF / water = 25 / 75, so that the polyether polyurethane is wet-coagulated into a porous structure. The polyether polyurethane is obtained by polymerizing a polymer diol mainly composed of polytetramethylene ether glycol (PTMG), MDI and a chain extender mainly composed of EG.

[0246] Next, toluene was used to remove polyethylene from the island-type composite fiber, transforming it into ultrafine fibers with an average fineness of about 0.008 dtex, resulting in a fiber substrate with a thickness of 1.3 mm.

[0247] Next, a polyurethane-based top layer solution was coated onto the release paper "AR-138" (manufactured by ASAHI ROLL) and dried, thereby forming a resin film 1 that serves as the top layer of the coating. This polyurethane-based top layer solution contained 100 parts by weight of a non-yellowing polycarbonate polyurethane solution "RESAMINE ME8116" (manufactured by Daihatsu Seika Co., Ltd., resin component 30% by weight), 20 parts by weight of a black pigment "RESAMINE DUT4790" (manufactured by Daihatsu Seika Co., Ltd.), 30 parts by weight of DMF, and 30 parts by weight of methyl ethyl ketone (MEK). The resulting resin film 1 had a thickness of 15 μm.

[0248] Next, a polyurethane intermediate layer solution is coated onto the aforementioned resin film 1 and dried, thereby forming a resin film 2, which serves as the intermediate layer of the coating layer. This polyurethane intermediate layer solution comprises 100 parts by weight of a single-component polyether polyurethane "RESAMINE ME8106" (manufactured by Daihatsu Seika Co., Ltd.), 20 parts by weight of a black pigment "RESAMINE DUT4790" (manufactured by Daihatsu Seika Co., Ltd.), 30 parts by weight of DMF, and 30 parts by weight of MEK. The total thickness of the resulting resin film 1 and resin film 2 (the combined thickness of the top and intermediate layers of the coating layer) is 35 μm.

[0249] Next, 100 parts by weight of crosslinking polyurethane adhesive "UD8310" (manufactured by Dainippon Seika Co., Ltd.), 10 parts by weight of crosslinking agent "RESAMINE NE crosslinking agent" (manufactured by Dainippon Seika Co., Ltd.), 2 parts by weight of crosslinking accelerator "RESAMINE HI-299" (manufactured by Dainippon Seika Co., Ltd.), 25 parts by weight of DMF, and 15 parts by weight of ethyl acetate were mixed to prepare a polyurethane adhesive solution. The obtained polyurethane adhesive solution was then subjected to a concentration of 130 g / m³. 2 The resin film 2, which is coated on the intermediate layer that forms the coating layer, is dried at 120°C for 15 seconds to evaporate the solvent, thus obtaining a resin film containing an adhesive layer.

[0250] Next, the adhesive layer of the resin film was bonded to the fiber substrate. A metal pressure roller with a 0.9 mm gap, approximately 65% ​​of the total thickness (1.4 mm) of the fiber substrate portion, was used to press the fiber substrate and the resin film containing the adhesive layer together, thereby impregnating the polyurethane adhesive into the porous polyurethane layer, resulting in a laminate. The resulting laminate was dried at 130°C for 3 minutes and then cured at 50°C for 3 days. The release paper was then peeled off, yielding the skin material.

[0251] [Example 3]

[0252] A 10 dtex island-type composite fiber was produced by melt spinning 45 parts by weight of polyamide 6 (sea component) and 55 parts by weight of polystyrene (island component) in the same melt system. This island-type composite fiber was stretched to three times its original length, crimped, and then cut into fibers of 51 mm in length. The resulting short fibers were opened using a carding machine and formed into a fiber web using a cross-laying machine. The fiber web was then stacked, needle-punched, impregnated with an aqueous solution containing 4% polyvinyl alcohol, dried, and surface-polished to produce a fiber with a thickness of 1.4 mm and a basis weight of 300 g / m². 2 A smooth, cohesive nonwoven fabric.

[0253] Next, the cohesive nonwoven fabric is impregnated in a DMF solution containing 15% by mass of a polyester polyurethane (100% modulus: 10 MPa) obtained by copolymerizing PEA, MDI and EG, so that the polyester polyurethane is impregnated in the cohesive nonwoven fabric.

[0254] Then immediately add a DMF solution containing 25% by mass of polycarbonate-based polyurethane (100% modulus: 10 MPa) at 340 g / m³. 2 The polycarbonate polyurethane is coated onto the surface of a nonwoven fabric, allowing it to permeate the fabric. This polycarbonate polyurethane is obtained by polymerizing a polymer diol obtained by copolymerizing PHC and polybutylene adipate (PBA), along with MDI and EG. Further, at a density of 600 g / m²... 2 Coat with a DMF solution containing 20% ​​by mass of the aforementioned polycarbonate polyurethane.

[0255] The obtained cohesive nonwoven fabric was immersed in a coagulation solution (40°C) with DMF / water ratio of 30 / 70 for 30 minutes to allow the coated polycarbonate polyurethane to solidify into a porous structure.

[0256] Next, after washing, toluene extraction was used to remove the polystyrene from the island-type composite fibers, transforming them into porous fibers. This resulted in a fiber substrate with a 1.6 mm thick polyurethane porous layer formed on the cohesive nonwoven fabric of polyamide 6 porous fibers. The thickness of the polyurethane porous layer was approximately 400 μm.

[0257] Next, the surface of the polyurethane porous layer laminated on the fiber substrate was sanded using 180-grit sandpaper, removing a portion of the outermost layer of polyurethane porous layer. At this point, the removed thickness was approximately 1 μm. Further, the back side, which is the opposite side of the polyurethane porous layer, was sanded using 180-grit sandpaper, resulting in a finished fiber substrate with a thickness of 1.1 mm.

[0258] Next, a polyurethane-based top layer solution is coated onto the release paper "DE-35" (manufactured by Dai Nippon Printing Co., Ltd.) and dried, thereby forming a resin film 3 that serves as the top layer of the coating. This polyurethane-based top layer solution comprises 100 parts by weight of a non-yellowing polycarbonate polyurethane solution "RESAMINE NES9022-15" (manufactured by Dai Nippon Seika Kogyo Co., Ltd., resin component 25% by weight), 20 parts by weight of a black pigment "Seikaseven BS-780" (manufactured by Dai Nippon Seika Kogyo Co., Ltd.), and 30 parts by weight of MEK. The thickness of the resin film 3 is 15 μm.

[0259] Next, a polyurethane intermediate layer solution is coated onto the resin film 3 and dried, thereby forming a resin film 4, which serves as the intermediate layer of the coating layer. This polyurethane intermediate layer solution comprises 100 parts by weight of a single-component polyether polyurethane "RESAMINE ME8116" (manufactured by Daihatsu Seika Co., Ltd.), 20 parts by weight of a black pigment "RESAMINE DUT4790" (manufactured by Daihatsu Seika Co., Ltd.), 30 parts by weight of DMF, and 30 parts by weight of MEK. The total thickness of the resulting resin film 3 and resin film 4 (the combined thickness of the top and intermediate layers of the coating layer) is 35 μm.

[0260] Next, 100 parts by weight of crosslinking polyurethane adhesive “TA205FT” (manufactured by DIC Corporation), 10 parts by weight of crosslinking agent “Takenate D110N” (manufactured by Mitsui Chemicals Co., Ltd.), 2 parts by weight of crosslinking accelerator “Crisvon Accel QS” (manufactured by DIC Corporation), 30 parts by weight of DMF, and 10 parts by weight of ethyl acetate were mixed to prepare a polyurethane adhesive solution. The obtained polyurethane adhesive solution was then subjected to a concentration of 130 g / m³. 2 The resin film 4, which is coated on the intermediate layer to form the coating layer, is dried at 120°C for 15 seconds to evaporate the solvent, thus obtaining a resin film containing an adhesive layer.

[0261] Next, the adhesive layer of the resin film is bonded to the polyurethane porous layer of the polished fiber substrate. A metal pressure roller with a 0.8 mm gap, having a total thickness (1.2 mm) of approximately 65% ​​of the thickness of the polyurethane porous layer in the polished fiber substrate plus the thickness of the fiber substrate portion without the polyurethane porous layer, is used to press the polished fiber substrate and the resin film containing the adhesive layer together. This allows the polyurethane adhesive to permeate the polyurethane porous layer, resulting in a laminate. The resulting laminate is dried at 130°C for 3 minutes and then cured at 50°C for 3 days. The release paper is then peeled off, yielding the skin material.

[0262] [Example 4]

[0263] A fiber substrate with a thickness of 1.1 mm after polishing was obtained using the same method as in Example 3.

[0264] Next, a polyurethane-based top layer solution is coated onto the release paper "DE-35" (manufactured by Dai Nippon Printing Co., Ltd.) and dried, thereby forming a resin film 5, which serves as the top layer of the coating layer. The polyurethane-based top layer solution comprises 100 parts by weight of a non-yellowing polyether polyurethane solution "RESAMINE ME8116" (manufactured by Dai Nippon Seika Kogyo Co., Ltd., resin component 30% by weight), 20 parts by weight of a black pigment "RESAMINE DUT4790" (manufactured by Dai Nippon Seika Kogyo Co., Ltd.), 30 parts by weight of DMF, and 30 parts by weight of MEK. The thickness of the resin film 5 is 15 μm.

[0265] Next, a polyurethane intermediate layer solution is coated onto the resin film 5 and dried, thereby forming a resin film 6, which serves as the intermediate layer of the coating layer. The polyurethane intermediate layer solution comprises 100 parts by weight of a single-component polyether polyurethane "RESAMINE ME8106" (manufactured by Daihatsu Seika Co., Ltd.), 20 parts by weight of a black pigment "RESAMINE DUT4790" (manufactured by Daihatsu Seika Co., Ltd.), 30 parts by weight of DMF, and 30 parts by weight of MEK. The total thickness of the resulting resin film 5 and resin film 6 (combined top and intermediate layers of the coating layer) is 35 μm.

[0266] Next, 100 parts by weight of crosslinking polyurethane adhesive "UD8310" (manufactured by Dainippon Seika Co., Ltd.), 10 parts by weight of crosslinking agent "RESAMINE NE crosslinking agent" (manufactured by Dainippon Seika Co., Ltd.), 2 parts by weight of crosslinking accelerator "RESAMINE HI-299" (manufactured by Dainippon Seika Co., Ltd.), 25 parts by weight of DMF, and 15 parts by weight of ethyl acetate were mixed to prepare a polyurethane adhesive solution. The obtained polyurethane adhesive solution was then subjected to a concentration of 130 g / m³. 2 The resin film 6, which is coated on the intermediate layer that forms the coating layer, is dried at 120°C for 15 seconds to evaporate the solvent, thus obtaining a resin film containing an adhesive layer.

[0267] Next, the adhesive layer of the resin film is bonded to the polyurethane porous layer of the fiber substrate. A metal pressure roller with a 0.8 mm gap, having a total thickness (1.2 mm) relative to the thickness of the polyurethane porous layer and the fiber substrate portion excluding the polyurethane porous layer, is used to press the fiber substrate and the resin film containing the adhesive layer together. This allows the polyurethane adhesive to permeate the polyurethane porous layer, resulting in a laminate. The resulting laminate is dried at 130°C for 3 minutes and then cured at 50°C for 3 days. The release paper is then peeled off, yielding the skin material.

[0268] [Example 5]

[0269] A fiber substrate with a thickness of 1.6 mm in which a polyurethane porous layer was formed in a cohesive nonwoven fabric made of porous fibers formed of polyamide 6 was obtained by the same method as in Example 3.

[0270] Next, using a 150-mesh gravure roller, a DMF solution containing 12 parts by weight of polyester polyurethane (100% modulus: 10MPa) obtained by polymerizing PEA, MDI and EG, 5 parts by weight of carbon black and 83 parts by weight of DMF is applied to the polyurethane porous layer of the fiber substrate and dried to form a coating layer with a thickness of about 10μm.

[0271] Next, for the fiber substrate with the coating layer, an embossing roller with a leather-like pattern is used to mold it at a temperature of 170°C, a pressure of 15 kg / cm, and a processing speed of 1.5 m / min, thereby forming an embossed pattern with an uneven surface on the coating layer. Further, the back side is sanded with 180-grit sandpaper to adjust the thickness to 1.3 mm, resulting in the outer skin material.

[0272] [Comparative Example 1]

[0273] A 10 dtex island-type composite fiber was produced by melt spinning 45 parts by weight of polyamide 6 (sea component) and 55 parts by weight of polystyrene (island component) in the same melt system. The island-type composite fiber was stretched to three times its original length, coated with a fiber oil to induce crimping, and then cut into fibers of 51 mm in length. The obtained short fibers were opened using a carding machine and formed into a fiber web using a cross-laying machine. The fiber webs were stacked, needle-punched, then impregnated in an aqueous solution containing 4% polyvinyl alcohol, dried, and the surface was polished, resulting in a thickness of 1.4 mm and a basis weight of 390 g / m². 2 A smooth, cohesive nonwoven fabric.

[0274] Next, the cohesive nonwoven fabric is impregnated in a DMF solution containing a total of 15% by mass of polycarbonate polyurethane (100% modulus: 10 MPa), so that the polycarbonate polyurethane is impregnated in the cohesive nonwoven fabric. The polycarbonate polyurethane is obtained by polymerizing the polymer diol obtained by copolymerizing PHC and PBA, as well as MDI and EG.

[0275] Then immediately add the DMF solution containing 25% by mass of the above-mentioned polycarbonate polyurethane at 340 g / m³. 2 The polycarbonate-based polyurethane is coated onto the surface of the nonwoven fabric, allowing it to permeate into the fabric. Further, at a concentration of 600 g / m²... 2A DMF solution containing 20% ​​by mass of the aforementioned polycarbonate polyurethane was applied.

[0276] The obtained cohesive nonwoven fabric was immersed in a coagulation solution (40°C) with DMF / water ratio of 30 / 70 for 30 minutes to allow the coated polycarbonate polyurethane to solidify into a porous structure.

[0277] Next, after washing, toluene extraction was used to remove the polystyrene from the island-type composite fibers, transforming them into porous fibers. This resulted in a fiber substrate with a 1.6 mm thick polyurethane porous layer formed on the cohesive nonwoven fabric of polyamide 6 porous fibers. The thickness of the polyurethane porous layer was approximately 400 μm.

[0278] Next, the surface of the polyurethane porous layer stacked in the fiber substrate was sanded using 180-grit sandpaper, removing a portion of the outermost polyurethane porous layer. At this point, the removed thickness was approximately 1 μm. Further, the back side, which is the opposite side of the polyurethane porous layer, was sanded using 180-grit sandpaper, resulting in a finished fiber substrate with a thickness of 1.6 mm.

[0279] Next, a resin film containing an adhesive layer was obtained using the same method as in Example 3.

[0280] Next, the adhesive layer of the resin film is bonded to the polyurethane porous layer of the polished fiber substrate. A metal pressure roller with a 1.4 mm gap, having a total thickness (1.7 mm) of approximately 65% ​​of the thickness of the polyurethane porous layer in the polished fiber substrate plus the thickness of the fiber substrate portion excluding the polyurethane porous layer, is used to press the polished fiber substrate and the resin film containing the adhesive layer together. This allows the polyurethane adhesive to permeate the polyurethane porous layer, resulting in a laminate. The resulting laminate is dried at 130°C for 3 minutes and then cured at 50°C for 3 days. The release paper is then peeled off, yielding the skin material.

[0281] [Comparative Example 2]

[0282] A fiber substrate with a thickness of 1.6 mm was obtained by using the same method as in Example 3, on which a polyurethane porous layer with a thickness of 1.6 mm was formed on a cohesive nonwoven fabric made of porous fibers of polyamide 6. The thickness of the polyurethane porous layer was approximately 400 μm.

[0283] Next, using a 150-mesh gravure roller, a DMF solution containing 30 parts by weight of black pigment "SEIKASEVEN BS-780" (manufactured by Dainichi Seika Co., Ltd., 20% carbon black, 9% polycarbonate polyurethane, and 71% DMF) and 70 parts by weight of silicone-modified polycarbonate polyurethane solution "RESAMINE NES9022-15" (manufactured by Dainichi Seika Kogyo Co., Ltd., 25% resin and 75% DMF) was coated onto the polyurethane porous layer of the fiber substrate, thereby forming a coating layer with a thickness of approximately 15 μm as a non-porous layer.

[0284] Next, for fiber substrates with a coating layer, 18 pieces / mm were used. 2 An embossing roller with recesses of an average depth of 60 μm and a fine embossed pattern across its entire surface is used for molding at a temperature of 170°C, a pressure of 15 kg / cm, and a processing speed of 1.5 m / min, thereby forming an embossed pattern with a textured surface on the coating layer. Next, the back side, which is the opposite side of the coating layer, is sanded with 180-grit sandpaper to obtain a skin material with a coating layer thickness of 1.2 mm.

[0285] [Comparative Example 3]

[0286] Polyamide 6 was melt-spun, stretched to three times its original length, coated with a fiber oil to induce crimping, dried, and cut into 51 mm lengths to produce 2.5 dtex staple fibers. Separately, polyethylene terephthalate was melt-spun, stretched to four times its original length, coated with a fiber oil to induce crimping, dried, and cut into 51 mm lengths to produce 1.5 dtex staple fibers. The polyamide 6 staple fibers and polyethylene terephthalate staple fibers were then blended at a weight ratio of 50:50, and opened using a carding machine to create a fiber web.

[0287] The fiber web was stacked, needle-punched, then impregnated in an aqueous solution containing 4% polyvinyl alcohol by mass, dried, and the surface was polished, resulting in a product with a thickness of approximately 1.4 mm and a weight per unit area of ​​400 g / m². 2 The cohesive nonwoven fabric.

[0288] Next, the cohesive nonwoven fabric is impregnated in a DMF solution containing a total of 15% by mass of a polyester polyurethane (100% modulus: 10 MPa) obtained by copolymerizing PEA, MDI and EG, so that the polyester polyurethane is impregnated in the cohesive nonwoven fabric.

[0289] The resulting cohesive nonwoven fabric was immersed in a coagulation solution (40°C) with DMF / water ratio of 30 / 70 for 30 minutes to allow the polyester polyurethane to solidify into a porous structure.

[0290] Next, the polyester polyurethane was solidified into a porous cohesive nonwoven fabric, washed with water, and then immersed in an aqueous solution containing 1.5% by mass of ethylene bis-stearamide. After drying, a fiber substrate with a thickness of 1.2 mm was obtained, which was formed by the cohesive nonwoven fabric of polyamide short fibers and polyethylene terephthalate short fibers.

[0291] Next, a DMF solution comprising 25 by mass of polycarbonate polyurethane (100% modulus: 10 MPa) obtained by polymerizing a polymer diol obtained by copolymerizing PHC and PBA, MDI, and EG was applied at 600 g / m³. 2 Coated onto the surface of the nonwoven fabric.

[0292] The obtained cohesive nonwoven fabric was immersed in a coagulation solution (40°C) with DMF / water = 30 / 70 for 30 minutes to wet solidify the coated polycarbonate polyurethane into a porous structure, thus obtaining a fiber substrate in which a polyurethane porous layer was formed on the cohesive nonwoven fabric.

[0293] Next, a resin film containing an adhesive layer was obtained using the same method as in Example 4.

[0294] Next, the adhesive layer of the resin film was bonded to the porous polyurethane layer of the fiber substrate. A metal pressure roller with a 0.8 mm gap, having a total thickness (1.2 mm) relative to the fiber substrate thickness and the porous coating layer thickness, was used to press the fiber substrate and the resin film containing the adhesive layer together. This allowed the polyurethane adhesive to permeate the porous polyurethane layer, resulting in a laminate. The resulting laminate was dried at 130°C for 3 minutes and then cured at 50°C for 3 days. After peeling off the release paper, the back side (the side without the coating layer) was sanded with 180-grit sandpaper, removing 0.7 mm to obtain the skin material.

[0295] [Comparative Example 4]

[0296] In Comparative Example 3, the laminate was dried at 130°C for 3 minutes and then cured at 50°C for 3 days. After the release paper was peeled off, the back side was not sanded. Otherwise, the same skin material was obtained.

[0297]

[0298] As shown in Table 1, the skin materials obtained in Examples 1 to 5 that satisfy formulas (I) and (II) are skin materials that are not prone to wrinkling, or that can easily recover their original shape even if wrinkles occur, and that have a lasting premium feel.

[0299] On the other hand, it can be seen that the skin materials obtained in Comparative Examples 1 to 4, which do not satisfy formulas (I) and (II), are skin materials that are prone to wrinkling, easily recover their original shape after wrinkling, and do not have a lasting sense of luxury.

Claims

1. A skin material, wherein the bending hysteresis moment 2HB (gf·cm / cm) and thickness h (mm) when bent in the surface direction satisfy the following equations (I) and (II): 2HB≤15h-10(I), 1.0≤h≤2.5(II).

2. The skin material according to claim 1, wherein it is selected from one or more of the straps and the cover.

3. The skin material according to claim 1 or 2, having an embossed surface, wherein the maximum height difference between the convex and concave portions of the embossed surface is less than 120 μm.

4. The skin material according to claim 1 or 2, wherein the arithmetic mean roughness is less than 10 μm.

5. The skin material according to claim 1 or 2, disposed on the outer surface side.

6. The outer material according to claim 1 or 2, used in a school bag.

7. A backpack that uses the outer material as described in claim 1 or 2.

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