Artificial leather and artificial leather manufacturing method

Abstract

The present invention addresses the problem of providing an artificial leather having excellent texture, surface wear resistance, and pilling resistance, and a method for producing the artificial leather. The artificial leather according to the present invention is an artificial leather containing superfine fibers, the maximum area of the cut surfaces of the superfine fiber bundles among the cut surfaces when cut at a depth of 0.3 mm from the surface is 4500 [mu] m2 or more, and the ratio of the number of the superfine fiber bundles having a cut surface area of 500 [mu] m2 or more to the total number of the cut surfaces of the superfine fiber bundles is 60% or more.

Description

Technical Field

[0001] This invention relates to artificial leather and a method for manufacturing artificial leather. Background Technology

[0002] Artificial leather samples possess softness and functionality that natural leather lacks, and therefore have been used in various applications such as clothing and materials.

[0003] In addition, artificial leather not only has requirements in terms of appearance (a surface that is closer to that of natural leather), feel (a soft feel with a moderate sense of expansion and fullness), and color rendering (the vividness and intensity of color), but also requires high-level performance in terms of physical properties such as lightfastness, pilling resistance, and abrasion resistance. Various proposals have been put forward to solve these problems.

[0004] For example, Patent Document 1 describes a leather sample comprising an ultrafine fiber aggregate formed of ultrafine fiber bundles and a polymeric elastomer incorporated therein, wherein the ultrafine fiber bundles have an average cross-sectional area of ​​0.1 to 30 μm. 2 It is formed from extremely fine single fibers with an average cross-sectional area of ​​40~400μm. 2 The aforementioned ultrafine fiber bundles are distributed at a rate of 600 to 4000 per mm in any cross-section parallel to the thickness direction of the aforementioned ultrafine fiber aggregate. 2 The density exists. It also records that the aforementioned leather samples have a high-end appearance, and exhibit good stability in terms of durability, surface abrasion resistance, and other qualities, making them highly practical.

[0005] Additionally, for example, Patent Document 2 describes a substrate for artificial leather, which is formed of a nonwoven fabric structure of extremely fine and long fiber bundles, the cross-sectional area of ​​which is 170~700μm. 2 With a flatness ratio below 4.0, in any cross-section of the nonwoven fabric structure parallel to the thickness direction, the cross-section of extremely fine and long fiber bundles is 1500~3000 / mm. 2 The range exists. The document describes the aforementioned artificial leather substrates as possessing, at a high level, both sensory and physical properties that were previously considered contradictory.

[0006] Existing technical documents

[0007] Patent documents

[0008] Patent Document 1: International Publication No. 2007 / 040144

[0009] Patent Document 2: Japanese Patent Application Publication No. 2008-308784 Summary of the Invention

[0010] The problem that the invention aims to solve

[0011] Generally, as described in Patent Documents 1 and 2, artificial leather is manufactured by the following methods: short-fibering multi-component fibers spun from two polymers with different solubility and decomposability; forming a web of desired weight using a carding machine, cross-laying machine, random carding machine, etc.; then entangled the fibers together to form a nonwoven fabric using needle punching, hydroentangling, etc.; then applying a solution or emulsion of a polymer elastomer, such as polyurethane, and allowing it to solidify; subsequently removing or reducing one component of the multi-component fibers to produce ultra-fine fibers; or, in the above methods, performing the impregnation / solidification of polymer elastomer and the process of forming the multi-component fibers into ultra-fine fibers in the reverse order; etc.

[0012] Although the quality of artificial leather has been improved by the technology described in Patent Documents 1 and 2, there are still problems such as easy fiber shedding and inability to meet the requirements for surface abrasion resistance and pilling resistance. There is a need for artificial leather that can meet the requirements of sensory and physical properties at a higher level.

[0013] In addition, while applying organic solvents and polymer elastomers to the surface of artificial leather can inhibit fiber shedding and slightly improve the surface's abrasion resistance and pilling resistance, it increases costs and poses adverse effects on human health and the environment when using organic solvents.

[0014] The purpose of this invention is to solve the above-mentioned problems and provide artificial leather with excellent feel, surface abrasion resistance and pilling resistance, as well as a method for manufacturing the artificial leather.

[0015] Problem Solving Methods

[0016] The inventors conducted various studies and found that by ensuring that the maximum area of ​​the cut surface of the ultrafine fiber bundle in the cut surface at a depth of 0.3 mm from the surface is at least a given value, and that the proportion of ultrafine fiber bundles is at least a given value, the above-mentioned problems can be solved, thus completing the present invention. That is, the present invention includes the following invention.

[0017] [1] A type of artificial leather containing extremely fine fibers,

[0018] In the cut surface at a depth of 0.3 mm from the surface, the maximum cut area of ​​the ultrafine fiber bundle is 4500 μm. 2 Furthermore, relative to the total number of cut surfaces of the extremely fine fiber bundle, the area of ​​the cut surface is 500 μm. 2 The proportion of the aforementioned ultrafine fiber bundles is over 60%.

[0019] [2] According to the artificial leather described in [1] above, wherein,

[0020] The total area of ​​the extremely fine fiber bundles in the cut surface is 50,000 μm. 2 / mm 2 above.

[0021] [3] According to the artificial leather described in [1] or [2] above, wherein,

[0022] The average diameter of the ultrafine fibers is less than 7.5 μm.

[0023] [4] The artificial leather according to any one of [1] to [3] above, wherein,

[0024] The average fineness of the ultrafine fibers is less than 0.5 dtex.

[0025] [5] The artificial leather according to any one of [1] to [4] above, wherein,

[0026] The ultrafine fibers are long fibers.

[0027] [6] The artificial leather according to any one of [1] to [5] above contains less than 45% by mass of a polymeric elastomer.

[0028] [7] A method for manufacturing artificial leather, which is the method for manufacturing artificial leather as described in any one of [1] to [6] above, the method comprising:

[0029] The process of preparing a fiber web from ultrafine fiber-generating fibers.

[0030] The process of forming a crimped fiber web by crimping the fiber web.

[0031] The process of overlapping multiple crimped fiber webs to form a web laminate

[0032] The process of bonding the laminations together to form a bonded fiber sheet, and

[0033] A process for removing at least one component from the ultrafine production fibers.

[0034] [8] The method for manufacturing artificial leather according to [7] above further comprises:

[0035] The process of impregnating the polymer elastomer into the cohesive fiber sheet.

[0036] The effects of the invention

[0037] According to the present invention, artificial leather with excellent feel, surface abrasion resistance, and pilling resistance, as well as a method for manufacturing the artificial leather, can be provided. Furthermore, according to the present invention, artificial leather with the above-mentioned effects can be obtained even without coating the surface of the artificial leather with organic solvents or polymer elastomers. Attached Figure Description

[0038] Figure 1 The image is a scanning electron microscope (SEM) image of the cut surface of the artificial leather of the present invention, taken at a depth of 0.3 mm from the surface using a single-edged razor and then photographed at 100x magnification.

[0039] Figure 2 It is printing Figure 1 The image is obtained by placing the printed surface on a flat surface lamp, illuminating it from the printed surface side, allowing the image to be transmitted to the back side, and then transferring the image by blackening the cut surface portion of the extremely fine fiber bundles present on the cut surface from the back side. Figure 1 (Images that are flipped horizontally). Detailed Implementation

[0040] Hereinafter, artificial leather according to embodiments of the present invention and a method for manufacturing artificial leather according to embodiments of the present invention (hereinafter sometimes referred to as "artificial leather of this embodiment" or "method for manufacturing artificial leather of this embodiment") will be described.

[0041] [Artificial Leather]

[0042] The artificial leather in this embodiment is an artificial leather containing extremely fine fibers. In a cut surface cut at a depth of 0.3 mm from the surface, the maximum area of ​​the cut surface of the extremely fine fiber bundle is 4500 μm. 2 Furthermore, relative to the total number of cut surfaces of the aforementioned ultrafine fiber bundles, the area of ​​the cut surface is 500 μm. 2 The proportion of the above-mentioned ultrafine fiber bundles is over 60%.

[0043] For the aforementioned artificial leather, by making the maximum area of ​​the cut surface of the ultrafine fiber bundles at a depth of 0.3 mm from the surface greater than a given value and the proportion of the number of ultrafine fiber bundles greater than a given value, artificial leather with excellent hand feel, surface abrasion resistance and pilling resistance can be produced.

[0044] It should be noted that the artificial leather of this invention refers to artificially manufactured products that have a feel close to that of natural leather, including napped artificial leather, grain artificial leather, etc. Furthermore, as variations resulting from the napped surface, napped artificial leather includes suede-like, velour-like, nubuck-like, etc.

[0045] In this specification, "the cut surface at a depth of 0.3 mm from the surface" refers to, in the case of piled synthetic leather, the cut surface when the difference between the thickness of the piled synthetic leather and the thickness from the side opposite to the piled surface of the fibers to the cut surface reaches 0.3 mm; and in the case of grain synthetic leather, the cut surface when the difference between the thickness of the fiber layer constituting the grain synthetic leather and the thickness from the side opposite to the resin layer of the fiber layer to the cut surface reaches 0.3 mm. It should be noted that this cut surface is parallel to the surface direction of the synthetic leather and orthogonal to the thickness direction.

[0046] In addition, in this instruction manual, "excellent feel" means that it has excellent density, softness, and other qualities, and a good tactile feel, which is close to that of natural leather.

[0047] The thickness of the artificial leather in this embodiment is not particularly limited. From the viewpoint of obtaining artificial leather with better feel, surface abrasion resistance and pilling resistance, it is preferably 0.1 to 2.0 mm, more preferably 0.3 to 1.5 mm, and even more preferably 0.5 to 1.2 mm.

[0048] It should be noted that the above "thickness" is a value measured according to JIS L1096(2010)(Method A).

[0049] The apparent density of the artificial leather in this embodiment is not particularly limited, but from the viewpoint of obtaining artificial leather with superior hand feel, surface abrasion resistance, and pilling resistance, 0.1 to 1.0 g / cm³ is preferred. 3 More preferably, it is 0.2~0.9 g / cm³. 3 More preferably, it is 0.3~0.8 g / cm³. 3 .

[0050] It should be noted that the above "apparent density" is a value determined according to JIS L1096(2010)(Method A).

[0051] The weight per unit area of ​​the artificial leather in this embodiment is not particularly limited, but from the viewpoint of obtaining artificial leather with better hand feel, surface abrasion resistance, and pilling resistance, it is preferably 100~1000 g / m². 2 More preferably, it is 150~800g / m 2 Further preferred is 200~600g / m 2 .

[0052] It should be noted that the above "weight per unit area" is a value determined according to JIS L1096(2010)(Method A).

[0053] The artificial leather used in this embodiment is not particularly limited, but from the viewpoint of more easily obtaining the effects of the present invention, artificial leather with a raised nap is preferred.

[0054] <Microfiber>

[0055] The ultrafine fibers contained in the artificial leather of this embodiment refer to fibers that have been ultrafined 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. Furthermore, the ultrafine fiber bundle described in this invention refers to a bundle formed by the aggregation of multiple ultrafine fibers, specifically a bundle composed of three or more closely spaced ultrafine fibers with a spacing of 6 μm or less between them, and the total cross-sectional area of ​​the aggregated ultrafine fibers is 60 μm. 2 The above is an aggregate of extremely fine fibers.

[0056] From the viewpoint of obtaining artificial leather with superior feel, surface abrasion resistance, and pilling resistance, the ultrafine fibers in this embodiment are preferably long fibers.

[0057] In this specification, "long fiber" refers to continuous fibers, not short fibers intentionally cut after spinning. More specifically, for example, it refers to filaments or continuous fibers that are not intentionally cut into short fibers with a length of about 3 to 80 mm. The fiber length of the island-type composite fiber before ultrafine fiberization, as described later, is preferably 100 mm or more, more preferably 200 mm or more. As long as it is technically possible to manufacture and is not inevitably cut during the manufacturing process, the aforementioned long fiber can be, for example, a continuous fiber with a fiber length of several meters, hundreds of meters, several kilometers, or more, manufactured by spunbonding and continuously spun. It should be noted that due to needle punching during bonding and surface polishing, sometimes a portion of the long fiber may be unavoidably cut into short fibers during the manufacturing process.

[0058] Examples of resins constituting the ultrafine fibers of this embodiment include, for instance, polyethylene terephthalate (hereinafter sometimes referred to as "PET"), isophthalic acid modified PET, sulfonated isophthalic acid modified PET, cationic dyeable PET, etc., aromatic polyesters such as polybutylene terephthalate and hexanediol terephthalate; aliphatic polyesters such as polylactic acid, polyethylene succinate, polybutylene succinate, polybutylene adipate, and polyhydroxybutyrate-polyhydroxyvalerate resin; nylons such as nylon 6, nylon 66, nylon 10, nylon 11, nylon 12, and nylon 6-12; and fibers such as polypropylene, polyethylene, polybutene, polymethylpentene, and chlorinated polyolefins. It should be noted that modified PET is PET obtained by replacing at least a portion of the esterifying dicarboxylic acid monomer units or diol monomer units of unmodified PET with substituted monomer units. Specific examples of modified monomer units that substituted dicarboxylic acid monomer units include units derived from isophthalic acid, sodium isophthalate sulfonate, sodium naphthalene dicarboxylate sulfonate, adipic acid, etc., that substituted terephthalic acid units. Specific examples of modified monomer units that substituted diol monomer units include units derived from diols such as butanediol and hexanediol that substituted ethylene glycol units.

[0059] From the viewpoint of obtaining artificial leather with excellent colorability, surface abrasion resistance, and pilling resistance, polyester resins such as aromatic polyesters and aliphatic polyesters are preferred. Furthermore, from the viewpoint of productivity and mechanical strength during spinning, aromatic polyesters such as polyethylene terephthalate (PET), isophthalic acid modified PET, sulfonic acid-modified isophthalic acid modified PET, and cationic dyeable PET are preferred; aromatic polyesters such as polylactic acid, polyethylene succinate, polybutylene succinate, polybutylene adipate, and polyhydroxybutyrate-polyhydroxyvalerate resins are preferred; nylons such as nylon 6, nylon 66, nylon 10, nylon 11, nylon 12, and nylon 6-12 are preferred; and polyolefins such as polypropylene, polyethylene, polybutene, polymethylpentene, and chlorinated polyolefins are preferred.

[0060] Without impairing the effects of the present invention, the resin constituting the ultrafine fibers of this embodiment 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, tick repellents, inorganic microparticles, etc.

[0061] In this embodiment, the maximum area of ​​the cut surface of the extremely fine fiber bundles in the artificial leather when cut at a depth of 0.3 mm from the surface is 4500 μm. 2 above.

[0062] From the viewpoint of obtaining synthetic leather with superior feel, surface abrasion resistance, and pilling resistance, the maximum cross-sectional area of ​​the aforementioned ultrafine fiber bundles is preferably 5000 μm. 2 The above, more preferably 5500μm 2 The above is further preferred to be 6000μm. 2 From the viewpoint of obtaining artificial leather with ease of manufacture and excellent appearance, a thickness of 30,000 μm is preferred. 2 Below, 25000μm is more preferred. 2 Hereinafter, 20000μm is further preferred. 2 The maximum area of ​​the cut surface of the aforementioned ultrafine fiber bundle is preferably 5000~30000 μm. 2 More preferably, it is 5500~25000μm 2 More preferably 6000~20000μm 2 .

[0063] It should be noted that the "maximum area of ​​the cut surface of the ultrafine fiber bundle" mentioned above is a value calculated based on a photograph of the cut surface of artificial leather taken at a depth of 0.3 mm from the surface using a scanning electron microscope (SEM) at 100x magnification. The specific measurement can be performed through the steps described in the examples.

[0064] For the artificial leather of this embodiment, when cut at a depth of 0.3 mm from the surface, the area of ​​the cut surface relative to the total number of cut surfaces of the extremely fine fiber bundles is 500 μm. 2 The proportion of the above-mentioned ultrafine fiber bundles is over 60%.

[0065] From the perspective of obtaining synthetic leather with superior feel, surface abrasion resistance, and pilling resistance, the area of ​​the cut surface is 500μm relative to the total number of cut surfaces of the aforementioned ultrafine fiber bundles. 2 The number ratio of the aforementioned ultrafine fiber bundles is preferably 61% or more, more preferably 63% or more, and even more preferably 65% ​​or more. When the artificial leather has a napped surface, considering the viewpoint that the appearance may be degraded because the substrate can be seen through the gaps between the napped fibers, it is preferably 95% or less, more preferably 93% or less, and even more preferably 90% or less. That is, the aforementioned number ratio is preferably 61-95%, more preferably 63-93%, and even more preferably 65-90%.

[0066] It should be noted that the above "the total number of cut surfaces relative to the ultrafine fiber bundle, the area of ​​the cut surface is 500 μm" refers to the area of ​​the cut surface. 2The above-mentioned ratio of the number of ultrafine fiber bundles is a value calculated based on a photograph of the cut surface of artificial leather taken at a depth of 0.3 mm from the surface using a scanning electron microscope (SEM) at 100x magnification. It can be specifically determined by the steps described in the examples.

[0067] From the perspective of obtaining synthetic leather with superior feel, surface abrasion resistance, and pilling resistance, the total area of ​​the cut surface of the ultrafine fiber bundles in the cut surface when cut at a depth of 0.3mm from the surface (converting the total area of ​​the cut surface of the ultrafine fiber bundles to per 1mm) is considered. 2 The preferred value is 25000 μm. 2 / mm 2 The above, more preferably 40000μm 2 / mm 2 The above is further preferred to be 50000μm. 2 / mm 2 From the viewpoint of obtaining synthetic leather with ease of manufacture and good tear strength, a thickness of 200,000 μm is preferred. 2 / mm 2 Below, 180000μm is more preferred. 2 / mm 2 Hereinafter, 150,000 μm is further preferred. 2 / mm 2 The total cross-sectional area of ​​the aforementioned ultrafine fiber bundle is preferably 25,000 to 200,000 μm. 2 / mm 2 More preferably, it is 40,000~180,000 μm 2 / mm 2 More preferably 50,000~150,000 μm 2 / mm 2 .

[0068] It should be noted that the "total area of ​​the cut surface of the ultrafine fiber bundle" mentioned above is a value calculated based on a photograph of the cut surface of artificial leather taken at a depth of 0.3 mm from the surface using a scanning electron microscope (SEM) at 100x magnification. It can be specifically measured through the steps described in the examples.

[0069] From the viewpoint of obtaining synthetic leather with superior feel, surface abrasion resistance, and pilling resistance, the average diameter of the ultrafine fibers in this embodiment is preferably 7.5 μm or less, more preferably 6.0 μm or less, further preferably 5.5 μm or less, and even more preferably 5.0 μm or less. There is no particular limitation on the lower limit; from the viewpoint of ease of manufacture and color development, it is, for example, 1.0 μm or more or 1.5 μm or more. In other words, the average diameter of the ultrafine fibers in this embodiment is preferably 1.0 to 7.5 μm, more preferably 1.5 to 6.0 μm.

[0070] From the viewpoint of obtaining synthetic leather with superior feel, surface abrasion resistance, and pilling resistance, the average fineness of the ultrafine fibers in this embodiment is preferably 0.50 dtex or less, more preferably 0.40 dtex or less, and even more preferably 0.30 dtex or less. There is no particular limitation on the lower limit, but from the viewpoint of ease of manufacture and color development, it is, for example, 0.01 dtex or more or 0.02 dtex or more. In other words, the average fineness of the ultrafine fibers in this embodiment is preferably 0.01 to 0.50 dtex, more preferably 0.01 to 0.40 dtex.

[0071] It should be noted that the above-mentioned "average diameter" and "average fineness" are values ​​calculated based on the cross-sectional area of ​​a randomly selected number of ultrafine fibers measured in a magnified photograph of the cross-section of the ultrafine fiber. Specifically, they can be measured through the steps described in the embodiments.

[0072] <Polymer Elastomers>

[0073] The artificial leather in this embodiment may contain a polymeric elastomer.

[0074] The polymer elastomer can be any polymer elastomer previously used in artificial leather. Any polymer elastomer can be used. For specific examples, polyurethane elastomer, acrylonitrile elastomer, olefin elastomer, polyester elastomer, and acrylic elastomer are available. Polyurethane elastomer and acrylic elastomer are preferred.

[0075] Examples of polyurethane elastomers include polymeric polyols with an average molecular weight of 500 to 3000 selected from polyester glycol, polyether glycol, polyether ester glycol, polycarbonate glycol, polycarbonate ether glycol, and polycarbonate glycol, and polyisocyanates selected from at least one of aromatic, alicyclic, or aliphatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate, and hexamethylene diisocyanate, which are combined as main components, and further combined with at least one low molecular weight compound having two or more active hydrogen atoms such as ethylene glycol and ethylenediamine in a given molar ratio, and then polymerized in one or more steps by melt polymerization, bulk polymerization, solution polymerization, etc., to obtain various polyurethane elastomers.

[0076] The polymer polyol component preferably accounts for 15-90% of the mass of the polyurethane elastomer.

[0077] Furthermore, examples of acrylic elastomers include various acrylic elastomers obtained by polymerizing an olefinically unsaturated monomer comprising a soft component, a hard component, and a crosslinking-forming component. The soft component is a monomer whose homopolymer has a glass transition temperature in the range of -90 to -5°C, and is preferably non-crosslinked. Examples include at least one soft component selected from methyl acrylate, n-butyl acrylate, isobutyl acrylate, isopropyl acrylate, n-hexyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate. The hard component is a monomer whose homopolymer has a glass transition temperature in the range of 50 to 250°C, and is preferably non-crosslinked. If the crosslinking forming component is at least one hard component selected from methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, cyclohexyl methacrylate, and (meth)acrylic acid, the crosslinking forming component is a monofunctional or polyfunctional olefinic unsaturated monomer unit capable of forming a crosslinked structure, or a compound capable of reacting with an olefinic unsaturated monomer unit introduced into the polymer chain to form a crosslinked structure, such as at least one crosslinking forming component selected from ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate.

[0078] Artificial leather made using polyurethane elastomers as the main polymer elastomer exhibits an excellent balance of hand feel and mechanical properties. Furthermore, by selecting appropriate types, the balance, including durability, is also excellent, making it a preferred choice. On the other hand, artificial leather made using acrylic elastomers is unsuitable for forming napped artificial leather because acrylic elastomers have lower adhesion to extremely fine fiber bundles compared to polyurethane elastomers, resulting in insufficient nap fixation. However, it is particularly preferred when forming grain-like artificial leather because the degree of hardening relative to the content is suppressed.

[0079] As a polymeric elastomer, it can contain different types mixed together, or it can contain different types in multiple portions. In addition, it can be made into a polymeric elastomer composition containing polymeric elastomers such as synthetic rubber as needed, in addition to the polymeric elastomers mainly composed of the aforementioned polyurethane elastomers, acrylonitrile elastomers, olefin elastomers, polyester elastomers, and acrylic elastomers.

[0080] From the viewpoint of obtaining artificial leather with excellent feel, the content of the above-mentioned polymer elastomer in the artificial leather is preferably 5 to 45% by mass, more preferably 7 to 40% by mass, and even more preferably 8 to 30% by mass.

[0081] <Other Ingredients>

[0082] The artificial leather of this embodiment may or may not contain components other than microfibers and polymeric elastomers. Examples of such other components include: other components contained in the microfibers described above, and the same components as those added to the polymeric elastomer liquid described in step (4) below. The aforementioned other components may be contained within at least one of the microfibers and the polymeric elastomers.

[0083] Considering the ease with which the desired effects of the other components can be achieved, as well as the properties of water absorption, water repellency, and stain resistance, the content of the other components relative to the quality of the artificial leather is preferably 0.5 to 10.0% by mass, more preferably 1.0 to 5.0% by mass, and even more preferably 1.5 to 3.0% by mass.

[0084] [Manufacturing methods for artificial leather]

[0085] The artificial leather of this embodiment is preferably manufactured by a manufacturing method comprising the following steps (1) to (4) and (6).

[0086] Process (1): The process of preparing a fiber web formed from ultrafine fiber-generating fibers.

[0087] Step (2): The step of crimping the above-mentioned fiber web to form a crimped fiber web.

[0088] Step (3): The step of overlapping multiple of the above-mentioned crimped fiber webs to form a web laminate.

[0089] Step (4): The process of bonding the above-mentioned laminations together to form a bonded fiber sheet.

[0090] Step (6): A step of removing at least one component from the above-mentioned ultrafine production fibers.

[0091] In addition, from the viewpoint of giving a feel and shape stability close to that of natural leather, the following process (5) can be included, and from the viewpoint of making a better feel, the following process (7) can be included.

[0092] Step (5): The step of impregnating the above-mentioned cohesive fiber sheet with the above-mentioned polymer elastomer.

[0093] Process (7): The process of dyeing artificial leather

[0094] The step (5) is preferably performed between steps (4) and (6), and the step (7) is preferably performed after step (6).

[0095] The manufacturing method of this embodiment, by including the above-described step (2), easily obtains a maximum area of ​​4500 μm for the cut surface of the extremely fine fiber bundle when cut at a depth of 0.3 mm from the surface. 2 Furthermore, relative to the total number of cut surfaces of the aforementioned ultrafine fiber bundles, the area of ​​the cut surface is 500 μm. 2 The artificial leather described above contains more than 60% of the aforementioned ultrafine fiber bundles. As a result, it is easy to obtain artificial leather with excellent hand feel, surface abrasion resistance, and pilling resistance.

[0096] The following is a description of each process.

[0097] <Process (1)>

[0098] Process (1) is the process of preparing a fiber web formed from ultrafine fiber-generating fibers.

[0099] As described above, ultrafine fibers refer to fibers that have been refined 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 produce such ultrafine fibers are called 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 mixing (mixed spinning) and composite spinning. Among these, island-type composite fibers are preferred from the viewpoint of obtaining artificial leather that can improve productivity through high-speed spinning and has excellent surface abrasion resistance and pilling resistance. From the same viewpoint, it is preferable to obtain a fiber web by melt spinning island-type composite fibers.

[0100] When the ultrafine fiber producing type fiber is an island-type composite fiber, island components are dispersed in the sea component that forms the matrix in the fiber cross section, and fiber bundles of ultrafine fibers can be produced by removing the sea component.

[0101] The following is a detailed description of a method for obtaining a fiber web by using island-type composite fibers as ultrafine fiber generating fibers and by melt spinning the island-type composite fibers.

[0102] As a resin that is included in the island component of the island-type composite fiber and subsequently becomes an ultrafine fiber, examples include resins that are the same as the resins constituting the ultrafine fibers described above.

[0103] As for the resin containing the marine components that are removed through extraction, decomposition, etc., within the island-type composite fiber, 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 of resin containing the island components and the manufacturing method.

[0104] Examples of resins 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 by dissolution with 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 use of solvents. From the viewpoint of melt spinning properties, water solubility, and fiber properties (fiber strength), polyethylene and polyvinyl alcohol resins are preferred, and polyethylene and modified polyvinyl alcohol are more preferred.

[0105] From the viewpoints of copolymerization, melt spinning and fiber water solubility, the preferred types of comonomers used in modified polyvinyl alcohol are α-olefins with 4 or fewer carbon atoms, such as ethylene, propylene, 1-butene, and isobutene; and vinyl ethers such as methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, and n-butyl vinyl ether.

[0106] The content of copolymer units in polyvinyl alcohol is preferably 1 to 20 mol%, more preferably 4 to 15 mol%, and even more preferably 6 to 13 mol%.

[0107] Furthermore, when the copolymer unit is ethylene, the fiber properties increase; therefore, ethylene-modified polyvinyl alcohol is more preferred. The ethylene unit content in ethylene-modified polyvinyl alcohol is preferably 4-15 mol%, more preferably 6-13 mol%.

[0108] 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 substantial, fuller, and denser surface texture. 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.

[0109] As a method for manufacturing fiber webs, the following method is preferred: using a so-called spunbond method to capture extremely fine fiber-generating fibers after melt spinning onto a web without cutting them, thereby forming a fiber web of long fibers as continuous fibers.

[0110] Specifically, a composite spinning nozzle with multiple nozzle holes arranged in a given pattern is used to continuously eject molten filaments of island-type composite fibers from the spinning nozzle at a given ejection speed. Substantial cooling and solidification are carried out by cooling air at any stage from directly below the nozzle to the suction device described later. A high-speed airflow is applied by a suction device such as an air nozzle / orifice to uniformly draw and refine the composite fibers to the target diameter or fineness.

[0111] High-speed airflow is used to achieve an average spinning speed within the range of 1000-6000 m / min, equivalent to the mechanical drafting speed in conventional spinning. Furthermore, depending on the texture of the resulting fiber web, long fiber webs can be manufactured using a spunbonding method. In this method, composite fibers are opened using a collision plate or airflow, while being drawn from the opposite side of the web and collected / accumulated on the collecting surface of a conveyor-belt-shaped moving web, thereby forming a long fiber web. Additionally, for the fiber web, a hot-pressing treatment can be performed to impart morphological stability, and the fiber web can also be melt-bonded simultaneously.

[0112] If the weight per unit area and thickness of the obtained fiber web are insufficient, adjustments can be made by layup (supplying one fiber web from a direction perpendicular to the direction of process travel and folding it along its approximate width direction (lateral direction), or folding a web supplied from a direction parallel to the direction of process travel along its length direction (longitudinal direction)) or stacking (overlapping multiple fiber webs) to achieve the desired weight per unit area and thickness. Mechanical bonding is performed using known methods such as needle punching to adjust morphological stability, fiber density, and the orientation of island-type fibers in the thickness direction. This results in three-dimensional bonding of the fibers constituting the fiber web, particularly in three-dimensional bonding of fibers between adjacent layers of a layered or stacked fiber web.

[0113] When using needle punching for cohesion treatment, it is important to appropriately select the type of needle (needle shape, size, hook shape, depth, number of hooks, position, etc.), the number of needle punches (the needle punching density per unit area obtained by multiplying the density of needles implanted in the needle plate by the number of strokes that make the plate act on the fiber web per unit area), and the needle perforation depth (the depth to which the needle acts on the fiber web).

[0114] As a cohesive treatment, methods such as needle punching and high-pressure water jet treatment can be cited, where at least one hook penetrates simultaneously or alternately from both sides. Furthermore, regarding the needle punching density, from the viewpoint of easily obtaining high wear resistance, 1500 to 5500 needles / cm² is preferably preferred. 2 Further preferred is 2000~5000 spines / cm 2 When the needle-punching density is within the above range, insufficient cohesion can be suppressed, preventing the artificial leather surface from becoming rough due to the fibers spreading out, and fiber cutting can be suppressed to prevent a decrease in cohesion.

[0115] <Process (2)>

[0116] Step (2) is a step of curling the above-mentioned fiber web to form a curled fiber web.

[0117] As a crimping process, there are, for example, physical and mechanical crimping methods such as passing the fiber between two gears, using a pressing roller (press-in crimping), pressing against the edge of a blade while bending and rubbing, air jetting, twisting, etc., as well as potential crimping methods using multi-component fibers or hollow fibers with different heat shrinkage, and methods combining these. The crimping process is preferably a physical and mechanical method capable of applying stable crimping to the fiber over a wide range; from the viewpoint of imparting an appropriate crimp rate to the fiber, pressing-in crimping is more preferred. In pressing-in crimping, from the viewpoint of obtaining synthetic leather with good process passability, better hand feel, better surface abrasion resistance, and better pilling resistance, pressing-in crimping using a roller with a concave-convex shape is preferred. As for the concave-convex shape, from the viewpoint of obtaining synthetic leather with better hand feel, better surface abrasion resistance, and better pilling resistance, a periodic concave-convex shape is preferred, and the average height difference between the concave and convex portions is preferably 1 to 30 mm, more preferably 1.5 to 25 mm, and even more preferably 2 to 20 mm. The distance between the recesses and the distance between the protrusions are preferably 1 to 30 mm, more preferably 1.5 to 25 mm, and even more preferably 2 to 20 mm.

[0118] From the viewpoint of obtaining synthetic leather with superior feel, surface abrasion resistance, and pilling resistance, the crimp rate during the crimping process by pressing the fiber web with rollers that impart a periodic concave-convex shape is preferably 120% or more, more preferably 150% or more, and even more preferably 170% or more. From the viewpoint of ease of manufacture, it is preferably 300% or less, more preferably 250% or less, and even more preferably 220% or less. That is, the crimp rate is preferably 120 to 300%, more preferably 150 to 250%, and even more preferably 170 to 220%.

[0119] It should be noted that the above "curl rate" refers to the ratio of the length along the concave-convex shape of the concave-convex roller to the length of the fiber web before the curling process (length along the concave-convex shape of the concave-convex roller / length of the fiber web before the curling process × 100 (%)).

[0120] In addition, after the crimping process, the crimped fiber web can be coated with a dispersing oil and a finishing oil without causing adverse effects.

[0121] <Process (3)>

[0122] Step (3) is a process of overlapping multiple of the above-mentioned crimped fiber webs to form a web laminate.

[0123] As a method for overlapping multiple crimped fiber webs, the crimping directions of the crimped fiber webs can all be set to the same direction for overlapping, or the conveying direction of the crimped fiber webs can be changed by 90° and overlapped while folding back and forth using a cross-laying method. From the viewpoint of being able to easily adjust the width of the cohesive fiber sheets, suppress the generation of unevenness in the width direction of the cohesive fiber sheets, that is, suppress unevenness in weight per unit area, the method of overlapping multiple crimped fiber webs is preferably cross-laying.

[0124] The number of overlapping fiber web layers is not particularly limited, but from the viewpoint of reducing uneven weight per unit area of ​​the cohesive fiber sheets and mechanical strength, it is preferable to have 2 or more layers, more preferably 3 or more layers. From the viewpoint of ease of manufacture, it is preferable to have 30 or fewer layers, more preferably 25 or fewer layers. That is, the number of overlapping fiber web layers is preferably 2 to 30 layers, more preferably 3 to 25 layers.

[0125] <Process (4)>

[0126] Step (4) is the process of binding the above-mentioned mesh stack together to form a bound fiber sheet.

[0127] In process (4), the web is mechanically bound together by known methods such as needle punching and high-pressure water jet treatment, so that the fibers constituting the fiber web are bound together in three dimensions, especially the fibers between adjacent layers of the layered fiber web that have been laid up and stacked are bound together in three dimensions.

[0128] When performing cohesion treatment by needle punching, various treatment conditions are appropriately selected, such as the type of needle (needle shape, size, hook shape, depth, number of hooks, position, etc.), the number of needle punches (the needle punching density per unit area obtained by multiplying the density of needles implanted in the needle plate by the number of strokes that make the plate act on the fiber web per unit area), and the needle perforation depth (the depth to which the needle acts on the fiber web).

[0129] When a mesh laminate containing stacked crimped fiber webs is needle-punched for bonding, the crimped fiber webs hook onto hooks, causing the moving fibers to carry more surrounding fibers, increasing the amount of fibers oriented in the thickness direction and improving bonding. This suppresses fiber shedding during surface friction, improving abrasion resistance and pilling resistance. Therefore, it is preferable to use a mesh laminate containing stacked crimped fiber webs for bonding via needle punching.

[0130] For the needle density used in needle punching, from the viewpoint of easily obtaining high wear resistance, a density of 1500 to 5500 needles / cm is preferred. 2 Further preferred is 2000~5000 spines / cm 2When the needle-punching density is within the above range, insufficient cohesion can be suppressed, preventing the artificial leather surface from becoming rough due to the fibers spreading out, and fiber cutting can be suppressed to prevent a decrease in cohesion.

[0131] Furthermore, oiling agents and antistatic agents can be applied to ultrafine fiber-generating fibers, fiber webs, crimped fiber webs, web laminates, and cohesive fiber sheets at any stage from spinning to cohesion treatment of the island-type composite fibers. Additionally, the cohesion can be pre-densified by immersing the ultrafine fiber-generating fibers, fiber webs, crimped fiber webs, web laminates, and cohesive fiber sheets in warm water at approximately 70-150°C for shrinkage treatment, as needed.

[0132] The unit area weight of the cohesive fiber sheet obtained by cohesion is preferably 100~2000 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 sheets as needed. Additionally, to further densify the cohesive fiber sheets that have been densified through heat shrinking, to fix the shape of the cohesive fiber sheets, and to smooth the surface, the fiber density can be further increased by hot pressing as needed.

[0133] <Process (5)>

[0134] Step (5) is the process of impregnating the above-mentioned polymer elastomer into the above-mentioned cohesive fiber sheet.

[0135] In step (5), at least one stage before and after the removal of the above-mentioned sea components, a polymeric elastomer is impregnated in the cohesive fiber sheet.

[0136] In the manufacture of the artificial leather in this embodiment, in order to give it a feel, shape stability and softness close to that of natural leather, it is preferable to impregnate the aforementioned polymer elastomer into the cohesive fiber sheet before removing the sea component.

[0137] In this way, by impregnating and imparting a polymeric elastomer before removing the sea element, gaps formed between the extremely fine fibers that have undergone sea element removal can be created after the sea element removal. As a result, the extremely fine fibers within the fiber bundles are less likely to be constrained by the polymeric elastomer; that is, the extremely fine fiber bundles are less affected by the polymeric elastomer, making it easier to obtain artificial leather with excellent softness. It should be noted that when impregnating and imparting a polymeric elastomer to the extremely fine fibers that have formed fiber bundles from island-type composite fibers after the sea element has been removed, the polymeric elastomer enters the gaps within the fiber bundles, thus constraining the extremely fine fibers forming the fiber bundles, resulting in artificial leather with a stiffer feel.

[0138] When applying the aforementioned polymeric elastomer to the aforementioned cohesive fiber sheet, a non-aqueous polymeric elastomer liquid prepared by dissolving or dispersing the polymeric elastomer in a solvent can be used, or an aqueous polymeric elastomer liquid prepared by dispersing the polymeric elastomer and a dispersant together in an aqueous medium can be used as needed. In the former case, a uniform polymeric elastomer liquid is easily obtained, while in the latter case, the amount of organic solvent used can be easily reduced.

[0139] The concentration of the polymer elastomer fluid, i.e. the content of polymer elastomer in the polymer elastomer fluid, is preferably 0.1 to 60% by mass.

[0140] Within the limits of not impairing the properties of the final artificial leather, various additives such as dyes, pigments and other colorants, coagulation regulators, antioxidants, ultraviolet absorbers, fluorescent agents, mildew inhibitors, penetrants, defoamers, lubricants, water repellents, oil repellents, thickeners, bulking agents, curing accelerators, foaming agents, polyvinyl alcohol, carboxymethyl cellulose and other water-soluble polymers can be appropriately added to the polymer elastomer liquid.

[0141] The details of the polymer elastomer used in process (5) are as described in the “Polymer Elastomer” section above.

[0142] Polymer elastomers can be fixed within cohesive fiber sheets by impregnating them with the elastomer and then solidifying the elastomer using conventional dry or wet methods. The dry method refers to any method that fixes the elastomer within the fiber sheet structure by removing solvents and dispersants through drying. The wet method refers to any method that temporarily or completely fixes the elastomer within the cohesive fiber sheet structure before removing the dispersant, by treating the cohesive fiber sheet structure impregnated with the elastomer liquid using a non-solvent or coagulant, or by heating the impregnated cohesive fiber sheet with an aqueous elastomer liquid containing a heat-sensitive gelling agent.

[0143] <Process (6)>

[0144] Step (6) is a step of removing at least one component from the above-mentioned ultrafine production type fiber. The above-mentioned component is preferably a resin containing a marine component in the island-type composite fiber. By removing the marine component, the ultrafine production type fiber can be transformed into a fiber bundle of ultrafine fibers.

[0145] As a method for removing marine components from resins, one example is the use of solvents or decomposing agents that can selectively remove only marine components from the resin.

[0146] 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.

[0147] When the marine component is insoluble in water but soluble in organic solvents, and the resin of the island component is a polyamide resin or a polyester resin, toluene, trichloroethylene, tetrachloroethylene, etc. can be cited as organic solvents for dissolving and removing the marine component.

[0148] In this embodiment, from an environmental perspective, water is preferred, and for resins that are poorly soluble in water, toluene, which has high resin solubility, is preferred.

[0149] When removing marine components, it is preferable to perform the immersion clamping process in parallel.

[0150] In addition, during the process from obtaining the web by melt spinning the island-type composite fiber to removing the sea component, heat shrinkage treatment (fiber shrinkage treatment) such as water vapor, hot water, and dry heat can be performed to densify the fiber.

[0151] <Process (7)>

[0152] Process (7) is the process of dyeing artificial leather.

[0153] Process (7) can be performed at any stage after the island-type fiber is transformed into an ultrafine fiber bundle.

[0154] In step (7), any dyeing method can be used, which uses dyes such as disperse dyes, reactive dyes, acid dyes, metal complex salt dyes, sulfur dyes, and sulfur vat dyes as the main dyes selected according to the type of fiber, or any dyeing machine commonly used in the dyeing of artificial leather, such as padder, jigger, circular, or wince.

[0155] In addition to dyeing, finishing processes can be performed as needed, including mechanical kneading in a dry state, relaxation treatment in a wet state after using dyeing machines, washing machines, etc., softener treatment, functional treatments such as flame retardants, antibacterial agents, deodorizers, and waterproof and oil-repellent agents, tactile improver treatments such as silicone resins, silk protein-containing treatment agents, and grip-enhancing resins, and design treatments using resins other than those mentioned above, such as coating colorants and enamel-style coating resins.

[0156] Similar to conventional artificial leather manufacturing, the artificial leather of this embodiment can be cut into multiple pieces along the thickness direction as needed, and the thickness can be adjusted by grinding the back side, or a solvent that can dissolve or swell the polymer elastomer or ultrafine fiber bundle can be applied to the back side.

[0157] The artificial leather of this embodiment can have a fibrous nap.

[0158] In forming the raised surface of the fibers, any known methods such as sanding or brushing based on sandpaper or needle cloth can be used. Alternatively, before or after such a raising process, a treatment solution containing a solvent capable of dissolving or swelling the polymer elastomer or ultrafine fiber bundles, such as a treatment solution containing dimethylformamide (DMF) when the polymer elastomer is a polyurethane elastomer, or a treatment solution containing phenolic compounds such as resorcinol, can be applied to the surface to be raised. This allows for fine-tuning of the constraint state of the ultrafine fiber bundles bonded by the polymer elastomer and ultrafine fiber bundles, the raised length of the ultrafine fibers in the artificial leather, and the surface friction durability.

[0159] In addition, after the above-mentioned napping treatment, the above-mentioned process (7) can be carried out to produce dyed artificial leather.

[0160] Example

[0161] The present invention will now be described in more detail through embodiments. It should be noted that the scope of the present invention is not limited by the content of the embodiments.

[0162] First, the measurement and evaluation methods used in the following examples and comparative examples are summarized and explained below.

[0163] <Average Diameter>

[0164] The average diameter of the polyester fibers was measured as described below.

[0165] Scanning electron microscope (SEM) images of the cross-section of the artificial leather were taken at 3000x magnification. Then, the cross-sections of 10 fibers were randomly selected from the SEM images and their cross-sectional areas were measured. The arithmetic mean of these cross-sectional areas was calculated, and the value calculated based on the following formula (1) was taken as the average diameter of the fibers.

[0166] Average diameter = (Average cross-sectional area / π) 1 / 2 ×2···Equation (1)

[0167] Average fineness

[0168] The average fineness of the polyester fibers was measured as described below.

[0169] Scanning electron microscopy (SEM) images of the cross-section of the artificial leather were taken at 3000x magnification. Then, cross-sections of 10 fibers were randomly selected from the SEM images, and their cross-sectional areas were measured. The arithmetic mean of these cross-sectional areas was calculated. The average cross-sectional area was then converted to the average fineness using the resin density.

[0170] <Content of polymeric elastomers>

[0171] The mass C of artificial leather cut into pieces weighing more than 1g was determined.

[0172] With the polymer elastomer dissolved in N,N-dimethylformamide (DMF), the aforementioned artificial leather was immersed in 300 mL of DMF at room temperature for 5 hours. The DMF was then removed by pressing. The resulting DMF was added to water, and the process of immersing the leather in DMF and pressing was repeated under the same conditions until the water no longer became cloudy, thus removing the polymer elastomer from the artificial leather. The polyester fiber, which was the remaining component from which the polymer elastomer had been removed, was dried to remove the DMF, and the mass D of the dried polyester fiber was measured. Then, the content of polymer elastomer in the artificial leather was determined based on the following formula (2).

[0173] The content of polymeric elastomer (mass%) = (CD) / C × 100 ··· Equation (2)

[0174] In the absence of insoluble polymer elastomers in DMF, the aforementioned artificial leather was immersed in 300 mL of hexafluoro-2-propanol (HFIP) at room temperature (25°C) for 12 hours to dissolve the polyester fibers. The remaining solid components were filtered out, washed with HFIP, dried, and the HFIP was removed. The mass E of the obtained solid was measured. Then, the content of polymer elastomers in the artificial leather was determined based on the following formula (3).

[0175] The content of polymeric elastomer (mass%) = E / C × 100 ··· Equation (3)

[0176] It should be noted that "solid components" refers to components other than solvents and liquid dispersants. That is, it refers to components other than liquids.

[0177] <Thickness, weight per unit area, and apparent density>

[0178] According to JIS L1096 (2010) (Method A), the thickness (mm) and weight per unit area (g / m²) of artificial leather were measured using a thickness measuring instrument (measuring element diameter: 10 mm) under a constant pressure of 23.5 kPa for 5 seconds. 2 Based on these values, the apparent density (g / cm³) of the artificial leather was calculated. 3 ).

[0179] <Determination of the area and number of ultrafine fiber bundles>

[0180] Prepare small pieces of artificial leather and secure the back side (the side without nap or resin layer) to the base using double-sided tape. Use a single-edged razor to slice the artificial leather at a depth of 0.3 mm from the surface, removing the surface side. Take a scanning electron microscope (SEM) image of the cut surface of the remaining side at 100x magnification. Print it (refer to...). Figure 1 The printing surface is placed on a flat panel light source, and light is shone from the printing surface side, causing the image to be transmitted to the back side. The cut surface portion of the extremely fine fiber bundles present on the cut surface is then blackened from the back side (see reference). Figure 2 The area of ​​the cut surface of the ultrafine fiber bundle and the number of cut surfaces were measured using Image-Pro Premier ver. 9.1 (manufactured by Japan Rober Co., Ltd.). The maximum area of ​​the cut surface of the ultrafine fiber bundle was taken as the maximum area of ​​the cut surface of the ultrafine fiber bundle. In addition, the total area of ​​the cut surfaces of the ultrafine fiber bundle was converted into per 1 mm. 2 This represents the total area of ​​the extremely fine fiber bundle. Furthermore, the area of ​​the cut surface was calculated to be 500 μm. 2 The above is the ratio of the number of ultrafine fiber bundles to the total number of cross-sections of ultrafine fiber bundles.

[0181] <20% strength>

[0182] Test pieces were prepared by cutting 16cm x 2.5cm lengthwise pieces from the obtained artificial leather. The test pieces were clamped in the fixtures of a tensile testing machine with 10cm intervals, allowing the artificial leather to be stretched longitudinally (in the direction of travel of process (3)). The SS curve was measured using Autograph at a stretching speed of 100mm / min. This operation was performed three times. The strength at 20% elongation was read from the obtained SS curve, and the average of the three measurements was taken as the longitudinal 20% strength (kgf / 2.5cm).

[0183] In addition, the clamps held in the tensile testing machine stretch the artificial leather in the transverse direction (direction that changes 90° from the direction of travel in process (3)) perpendicular to the longitudinal direction. In addition, the transverse 20% strength (kgf / 2.5cm) is calculated in the same way as above.

[0184] Wear Reduction

[0185] According to JIS L 1096 (2020) (8.19.5 E Martindale method), the Martindale wear tester was used at a compressive load of 12 kPa (gf / cm). 2The test was conducted under the condition of 350 million wear cycles to calculate the wear reduction on the surface of the artificial leather.

[0186] <Pilling>

[0187] According to JIS L 1096 (2020) (8.19.5 E Martindale method), under a pressing load of 12 kPa (gf / cm²), 2 Under the following conditions, the wear count was recorded in Table 1, and the pilling of the artificial leather surface after the test was determined by visual observation and touch according to the following criteria.

[0188] A: No hair balls formed by hair aggregation were found; the surface feels smooth and flat.

[0189] B: Although it looks like there are a few clumps of fur, you can't feel any tufts of fur, and the texture is slightly rough.

[0190] C: A ball of hair was observed, which felt rough to the touch.

[0191] <Feel>

[0192] The feel of the obtained artificial leather after bending was judged by visual observation and touch according to the following criteria.

[0193] A: It has a full feel, does not crack (create wrinkles), and has an excellent softness.

[0194] B: The feel is characterized by one or more of the following: insufficient fullness, cracking (causing creases and wrinkles), and stiffness.

[0195] <Appearance>

[0196] The appearance of the obtained artificial leather was judged by visual inspection according to the following criteria.

[0197] A: The fibers do not clump together; they are finely dispersed and have a uniform length.

[0198] B: The fibers are clustered together and spread out in a coarse and disordered manner, with uneven lengths.

[0199] [Example 1]

[0200] A water-soluble thermoplastic polyvinyl alcohol resin (sea component) and isophthalic acid-modified polyethylene terephthalate (PET modified with 6 mol% isophthalic acid) (island component) were extruded through a melt composite spinning nozzle (island number: 25 islands / fiber) at 270°C with a sea component / island component ratio of 25 / 75 (mass ratio). The spinning was carried out at a spinning speed of 3500 m / min to obtain a fiber web containing island-type composite fibers with an average fineness of 2.95 dtex.

[0201] Next, after hot pressing with calendering rollers, the web is pressed with rollers that impart a concave-convex shape, giving it a concave-convex shape in the width direction of the fiber web with a crimp rate of 200% (applying crimping treatment).

[0202] Next, the fiber web, after being crimped, is folded along its length, with seven fiber webs overlapping and cross-laid to form a layered web. Then, using 1-hook and 6-hook needles at a needle density of 3500 needles / cm², it is... 2 The laminated mesh was needle-punched, resulting in a weight of 385 g / m² per unit area. 2 The cohesive fiber sheet has been curled longitudinally.

[0203] Next, the cohesive fiber sheet was steam-treated at 110°C and 23.5%RH. Then, after drying in an oven at 90–110°C, it was further hot-pressed at 120°C, resulting in a surface area weight of 755 g / m². 2 Specific gravity 0.65 g / cm³ 3 Hot-pressed fiber sheet with a thickness of 1.16mm.

[0204] Next, 1.5 parts by mass of a carbodiimide crosslinking agent and 2.7 parts by mass of ammonium sulfate were added to a polycarbonate-based non-yellowing polyurethane (polyurethane (1)) emulsion, relative to 100 parts by mass of the polymeric elastomer, so that the solid content of the polymeric elastomer was 16% by mass. The resulting emulsion was impregnated into a hot-pressed fiber sheet at a pick-up ratio of 52%, so that the solid content of the polymeric elastomer was adjusted to 10% by mass relative to the total of polyester fibers and polymeric elastomer in the heat-shrinkable fiber sheet. Then, the hot-pressed fiber sheet impregnated with the emulsion was subjected to wet heat treatment at 110°C and 29%RH gas atmosphere, and further dried at 150°C to obtain a hot-pressed fiber sheet endowed with polymeric elastomer.

[0205] Then, by simultaneously impregnating and clamping the hot-pressed fiber sheet coated with a polymer elastomer and subjecting it to high-pressure water jet treatment, and immersing it in hot water at 95°C for 10 minutes, the water-soluble thermoplastic polyvinyl alcohol resin of the sea component, which is the island-type composite fiber, is dissolved and removed, forming extremely fine fibers of isophthalic acid-modified polyethylene terephthalate with an average diameter of 3.02 μm and an average fineness of 0.1 dtex. After drying, the back side is sanded with #320 sandpaper, and the main side is sanded with #320 and #400 sandpaper, thereby forming a fiber-reinforced napped surface, resulting in artificial leather with a fiber-reinforced napped surface.

[0206] The artificial leather was dyed with disperse dyes at 120°C, resulting in a weight per unit area of ​​439 g / m². 2 Apparent density: 0.499 g / cm³ 3 Dyed artificial leather with a thickness of 0.88 mm was obtained. The measurement and evaluation results of the obtained artificial leather are shown in Table 1.

[0207] [Example 2]

[0208] In Example 1, a curling treatment was performed with a curl rate of 175%, and similarly, dyed artificial leather was obtained. The measurement and evaluation results of the obtained artificial leather are shown in Table 1.

[0209] [Example 3]

[0210] In Example 1, artificial leather was manufactured with a thickness of 0.68 mm. Similarly, dyed artificial leather was also obtained. The measurement and evaluation results of the obtained artificial leather are shown in Table 1.

[0211] [Example 4]

[0212] In Example 3, a curling treatment was performed with a curl rate of 175%, and similarly, dyed artificial leather was obtained. The measurement and evaluation results of the obtained artificial leather are shown in Table 1.

[0213] [Example 5]

[0214] In Example 3, a fiber web that has undergone a crimping treatment in the width direction is stacked in the direction of travel of the cohesive fiber sheet (the direction of travel of the process) to form a laminated web, thereby forming a cohesive fiber sheet that has undergone a crimping treatment in the transverse direction. In addition, dyed artificial leather is obtained in the same way. The measurement and evaluation results of the obtained artificial leather are shown in Table 1.

[0215] [Example 6]

[0216] In Example 1, polyethylene was used as the sea element. The fiber-coated sheet was shrunk in hot water at 90°C and pressed using a cooled roller to obtain a heat-shrinkable mesh-coated sheet. A DMF solution (18.5% by mass solids) of polycarbonate-based polyurethane (polyurethane (2)) as the polymer elastomer was used to adjust the solids content of the polymer elastomer relative to the total of polyethylene terephthalate fibers and polymer elastomer in the hot-pressed fiber sheet to 30% by mass. Toluene was used to dissolve and remove the polyethylene as the sea element, and the thickness was adjusted to 0.78 mm. Similarly, dyed artificial leather was obtained. The measurement and evaluation results of the obtained artificial leather are shown in Table 1.

[0217] [Example 7]

[0218] In Example 6, a curling treatment was performed with a curl rate of 175%, and similarly, dyed artificial leather was obtained. The measurement and evaluation results of the obtained artificial leather are shown in Table 1.

[0219] [Example 8]

[0220] In Example 7, a DMF solution (18.5% by mass of solids) of an ether-based polyurethane (polyurethane (3)) as a polymeric elastomer was used, and dyed artificial leather was obtained in the same manner. The determination and evaluation results of the obtained artificial leather are shown in Table 1.

[0221] [Comparative Example 1]

[0222] In Example 1, no curling treatment was performed; otherwise, dyed artificial leather was obtained. The measurement and evaluation results of the obtained artificial leather are shown in Table 2.

[0223] [Comparative Example 2]

[0224] In Example 3, no curling treatment was performed; otherwise, dyed artificial leather was obtained in the same manner. The measurement and evaluation results of the obtained artificial leather are shown in Table 2.

[0225] [Comparative Example 3]

[0226] In Example 5, no curling treatment was performed, and the thickness was set to 0.80 mm. Otherwise, dyed artificial leather was obtained in the same manner. The measurement and evaluation results of the obtained artificial leather are shown in Table 2.

[0227] [Comparative Example 4]

[0228] In Example 6, no curling treatment was performed; otherwise, dyed artificial leather was obtained in the same manner. The measurement and evaluation results of the obtained artificial leather are shown in Table 2.

[0229] [Comparative Example 5]

[0230] In Example 6, spinning was performed at a spinning speed of 800 m / min, and similarly, island-type composite fibers were obtained. These island-type composite fibers were then stretched in a warm water bath at a stretch ratio of 2.7 times, thereby obtaining 4.0 dtex island-type composite fibers. Next, a crimping device was used to give the 4.0 dtex island-type composite fibers an uneven shape (performing crimping treatment), resulting in a crimp rate of 9.0%. A fiber web formed from the crimped island-type composite fibers was then produced using a carding machine.

[0231] Next, the fiber web is folded along its length, overlapping seven fiber webs while cross-laying them to create a layered web. Then, a 1-hook needle is used to prick the web at a density of 2500 needles / cm. 2 The laminated mesh was needle-punched, resulting in a weight of 1128 g / cm³ per unit area. 2 Cohesive fiber sheets.

[0232] Next, a hot-pressed fiber sheet was obtained using the same method as in Example 6. The hot-pressed fiber sheet was then infused with a polymer elastomer, the marine components of the island-type composite fiber were dissolved and removed, and a raised fiber surface was formed, resulting in artificial leather with a raised fiber surface. The measurement and evaluation results of the obtained artificial leather are shown in Table 2.

[0233] [Comparative Example 6]

[0234] In Comparative Example 5, after hot pressing the fiber web formed from the obtained short fibers with a calendering roller, it was pressed with a roller that imparted an uneven shape. When the uneven shape was imparted to the width direction of the fiber web with a crimp rate of 200% (performing a crimping process), the short fiber web broke and could not be processed further.

[0235] [Comparative Example 7]

[0236] In Comparative Example 3, the acupuncture treatment was increased to a needle density of 5900 needles / cm². 2 In addition, dyed artificial leather was also obtained. The results of the determination and evaluation of the obtained artificial leather are shown in Table 2.

[0237]

[0238]

[0239] As shown in Table 1, the artificial leathers obtained in Examples 1-8 have excellent hand feel, surface abrasion resistance, and pilling resistance.

[0240] On the other hand, it can be seen that the maximum area of ​​the cut surface of the extremely fine fiber bundle when cut at a depth of 0.3 mm from the surface is not 4500 μm. 2 The above-mentioned artificial leathers (comparative examples 1, 2 and 4) do not possess excellent hand feel, excellent surface abrasion resistance and pilling resistance.

[0241] Furthermore, it is known that the maximum area mentioned above is 4500 μm. 2 The above refers to the total number of cut surfaces relative to the extremely fine fiber bundle, with a cut surface area of ​​500 μm. 2 Artificial leather with a proportion of less than 60% of the above-mentioned fine fiber bundles (Comparative Example 3) has a poor hand feel.

[0242] Furthermore, it is known that by not subjecting the fiber web to crimping and increasing the needle density of the needle-punching process to 5900 needles / cm², the desired effect can be achieved. 2 For the artificial leather used to improve the cohesion of the fiber web (Comparative Example 7), the area of ​​the cut surface is 500 μm. 2 The proportion of the above-mentioned ultrafine fiber bundles is less than 60%, resulting in poor feel and appearance quality.

Claims

1. A type of artificial leather comprising extremely fine fibers, In the cut surface at a depth of 0.3 mm from the surface, the maximum cut area of ​​the ultrafine fiber bundle is 4500 μm. 2 Furthermore, relative to the total number of cut surfaces of the extremely fine fiber bundle, the area of ​​the cut surface is 500 μm. 2 The proportion of the aforementioned ultrafine fiber bundles is over 60%.

2. The artificial leather according to claim 1, wherein, The total area of ​​the extremely fine fiber bundles in the cut surface is 50,000 μm. 2 / mm 2 above.

3. The artificial leather according to claim 1 or 2, wherein, The average diameter of the ultrafine fibers is less than 7.5 μm.

4. The artificial leather according to any one of claims 1 to 3, wherein, The average fineness of the ultrafine fibers is less than 0.5 dtex.

5. The artificial leather according to any one of claims 1 to 4, wherein, The ultrafine fibers are long fibers.

6. The artificial leather according to any one of claims 1 to 5, comprising less than 45% by mass of a polymeric elastomer.

7. A method for manufacturing artificial leather, which is the method for manufacturing artificial leather according to any one of claims 1 to 6, the method comprising: The process of preparing a fiber web from ultrafine fiber-generating fibers. The process of forming a crimped fiber web by crimping the fiber web. The process of overlapping multiple crimped fiber webs to form a web laminate The process of bonding the laminations together to form a bonded fiber sheet, and A process for removing at least one component from the ultrafine production fibers.

8. The method for manufacturing artificial leather according to claim 7, further comprising: The process of impregnating the polymer elastomer into the cohesive fiber sheet.

Images