TW202548112A - Artificial leather and its manufacturing methods - Google Patents

Abstract

An artificial leather comprising ultrafine fibers containing polyester resin, wherein in the longitudinal section of the aforementioned artificial leather, the area proportion A of ultrafine fibers oriented in the thickness direction within the range of -30° to +30° is 4.5% or less, and in the transverse section of the aforementioned artificial leather, the area proportion B of ultrafine fibers oriented in the thickness direction within the range of -30° to +30° is A/B ≤ 0.9.

Description

Artificial leather and its manufacturing methods

This invention relates to artificial leather and a method for manufacturing artificial leather.

Artificial leather and other leather-like sheets possess softness and functionality that natural leather lacks, thus being used in various applications such as clothing and materials. Furthermore, artificial leather is required to meet all requirements at a high level in terms of physical properties such as lightfastness, pilling resistance, and abrasion resistance, as well as in terms of appearance (closer to the surface feel of natural leather), texture (combining a soft hand feel with a suitable degree of bulkiness or fullness), and color rendering (the vividness or intensity of color). Various proposals have been developed to address these requirements.

For example, Patent 1 describes a leather-like sheet comprising an extremely fine fiber entanglement composed of extremely fine fiber bundles and a polymer elastomer endowed therein. The aforementioned extremely fine fiber bundles are composed of extremely fine monofilaments with an average cross-sectional area of 0.1–30 ^μm² , and their average cross-sectional area is 40–400 ^μm² . The aforementioned extremely fine fiber bundles exist at a density of 600–4000 fibers/ ^mm² in any cross-section parallel to the thickness direction of the aforementioned extremely fine fiber entanglement. The leather-like sheet is described as having excellent softness. (Prior art patent documents)

Patent Document 1: International Publication No. 2007/040144

The problem this invention aims to solve: Artificial leather is generally dyed to enhance design and meet sensual requirements, but this process involves a large amount of water. Furthermore, from a sustainability perspective, there are significant requirements to reduce water consumption. On the other hand, thermosol dyeing is an example of a water-saving method, but artificial leather dyed using this method tends to have strong elasticity and poor softness.

The purpose of this invention is to provide an artificial leather that solves the aforementioned problems, exhibiting minimal elasticity and a soft texture even without softening treatment, as well as a method for manufacturing the same. This invention aims to provide a means to solve the problem.

Through various reviews, the inventors discovered that by setting specific values and ratios for the area occupied by extremely fine fibers oriented within a specific range in both the longitudinal and transverse sections of artificial leather, the aforementioned problem can be solved, thus completing this invention. In other words, this invention includes the following features.

[1] An artificial leather comprising ultrafine fibers containing polyester resin, wherein in the longitudinal section of the aforementioned artificial leather, the area ratio A of the ultrafine fibers oriented in the thickness direction within the range of -30° to +30° is 4.5% or less, and in the transverse section of the aforementioned artificial leather, the area ratio B of the ultrafine fibers oriented in the thickness direction within the range of -30° to +30° is A/B≦0.9 to the aforementioned area ratio A. [2] The artificial leather described in [1] above, wherein the average diameter of the aforementioned ultrafine fibers is 7.5 μm or less. [3] The artificial leather described in [1] or [2] above, wherein the average fineness of the aforementioned ultrafine fibers is 0.50 dtex or less. [4] The artificial leather described in any of [1] to [3] above, wherein the aforementioned ultrafine fibers are long fibers. [5] The artificial leather described in any of [1] to [4] above, wherein the aforementioned polyester resin is polyethylene terephthalate. [6] The artificial leather described in any of [1] to [5] above, wherein the inherent viscosity of the aforementioned polyester resin is 0.63 dl/g or less. [7] The artificial leather described in [5] above, wherein the aforementioned polyethylene terephthalate comprises dicarboxylic acid units and diol units, wherein 94 mol% or more of the aforementioned dicarboxylic acid units are structural units derived from terephthalic acid. [8] The artificial leather described in [7] above, wherein the aforementioned polyethylene terephthalate is recycled polyethylene terephthalate. [9] A method for manufacturing artificial leather, which is the method for manufacturing artificial leather as described in any of [1] to [8] above, comprising: a step of preparing a fiber web formed from extremely fine fiber-producing fibers; a step of forming a twisted fiber sheet using the aforementioned fiber web; a step of shrinking the aforementioned twisted fiber sheet and removing at least one component from the aforementioned extremely fine fiber-producing fibers to obtain an artificial leather matrix; and a step of dyeing the aforementioned artificial leather matrix; wherein the ratio (Y/X) of the strength X of the yield point in the transverse direction of the aforementioned fiber web to the maximum strength Y after the yield point is 4.0 or less. [10] The method for manufacturing artificial leather as described above [9] does not impregnate with polymeric elastomers before extracting a component from the aforementioned ultra-fine fiber-producing fibers. Effects of the Invention

According to the present invention, there is a method for manufacturing artificial leather that has little elasticity and a soft texture even without softening treatment.

The following describes the form of artificial leather of the present invention and the method of manufacturing artificial leather of the present invention (hereinafter also referred to as "artificial leather of the present invention" and "method of manufacturing artificial leather of the present invention").

[Artificial Leather] The artificial leather of this embodiment is an artificial leather containing ultrafine fibers of polyester resin. In the longitudinal section of the aforementioned artificial leather, the area ratio A of ultrafine fibers oriented in the thickness direction within the range of -30° to +30° is 4.5% or less. In the transverse section of the aforementioned artificial leather, the area ratio B of ultrafine fibers oriented in the thickness direction within the range of -30° to +30° is A/B≦0.9.

The artificial leather of this embodiment, by having the above-mentioned structure and achieving an appropriate degree of cross-linking of the extremely fine fibers, can become an artificial leather with low elasticity and a soft texture even without softening treatment. Furthermore, the artificial leather of this invention refers to that which has a texture close to artificially manufactured natural leather, including napped artificial leather and grain artificial leather. Moreover, napped artificial leather includes variations of the napped surface such as suede, velvet, and nubuck.

In this specification, when stretching artificial leather, the direction of least stretchability refers to the "longitudinal" direction of the artificial leather, and the direction orthogonal to that direction refers to the "lateral" direction. Furthermore, the flow direction during the manufacturing of artificial leather is the "longitudinal" direction. In this specification, "Area Ratio A" and "Area Ratio B" are values calculated by cutting the artificial leather in the longitudinal or transverse thickness direction and taking a 150x magnified photograph of the resulting cross-section using a scanning electron microscope (SEM). Area Ratio A and Area Ratio B are more specifically determined according to the procedures described in the embodiments.

From the perspective of achieving artificial leather with less elasticity and a softer texture, the area ratio A is 4.5% or less, preferably 4.2% or less, more preferably 4.0% or less, and especially preferably 3.8% or less. From the perspective of mechanical properties such as tensile strength, elongation, and tear strength, it is preferably 0.1% or more, more preferably 0.2% or more, and especially preferably 0.3% or more. A suitable range is preferably 0.1% to 4.5%, more preferably 0.2% to 4.2%, especially preferably 0.3% to 4.0%, and even more preferably 0.3% to 3.8%. The area ratio A can be adjusted to the desired value by adjusting the number of crossovers between the fibers of the fiber web.

The ratio of area ratio A to area ratio B, A/B, is A/B≦0.9. From the perspective of obtaining artificial leather with less elasticity and a softer texture, A/B≦0.8 is preferred, A/B≦0.7 is even better, and A/B≦0.6 is especially better. From the perspective of mechanical properties such as tensile strength, elongation, and tear strength, A/B≧0.1 is preferred, A/B≧0.2 is even better, and A/B≧0.3 is especially better. As a suitable range, it is preferred to be 0.1≦A/B≦0.9, more preferably 0.1≦A/B≦0.8, even more preferably 0.2≦A/B≦0.7, and even more preferably 0.3≦A/B≦0.6, etc.

From the perspective of obtaining artificial leather with less elasticity and a softer texture, the area ratio B is preferably 5.5% or less, more preferably 5.4% or less, and especially preferably 5.3% or less. From the perspective of obtaining artificial leather with the desired width, it is preferably 1.0% or more, more preferably 2.0% or more, and especially preferably 3.0% or more. As a suitable range, it is preferably 1.0 to 5.5%, more preferably 2.0 to 5.4%, and especially preferably 3.0 to 5.3%. The area ratio B can be adjusted by increasing the width of the artificial leather after dyeing. The higher the proportion of increasing the width of the artificial leather, the more it can be reduced; the smaller the proportion of increasing the width of the artificial leather, the more it can be increased.

The thickness of the artificial leather in this embodiment is not particularly limited. However, from the viewpoint of obtaining artificial leather with less elasticity and a softer texture, 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. Furthermore, the above-mentioned "thickness" is a value measured according to JIS L1096(2010)(Method A).

The apparent density of the artificial leather in this embodiment is not particularly limited, but from the viewpoint of obtaining artificial leather with less elasticity and a softer texture, it is preferably 0.10 to 1.00 g/ ^cm³ , more preferably 0.20 to 0.80 g/ ^cm³ , even more preferably 0.30 to 0.60 g/ ^cm³ , and even more preferably 0.35 to 0.48 g/ ^cm³ . Furthermore, the above-mentioned "apparent density" is a value measured according to JIS K6505 (1995) 5.2.2.

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 less elasticity and a softer texture, it is preferably 100 to 1000 g/ ^m² , more preferably 150 to 800 g/ ^m² , and even more preferably 200 to 600 g/ ^m² . Furthermore, the above-mentioned "weight per unit area" is a value measured according to JIS L1096(2010)(Method A).

There are no particular limitations on the type of artificial leather used in this embodiment, but from the viewpoint of more easily achieving the effects of this invention, artificial leather with a plush surface, i.e., plush artificial leather, is preferred.

<Ultra-fine fibers> The ultra-fine fibers contained in the artificial leather of this embodiment are fibers that have been made extremely fine by removing at least one component from a multi-component system fiber (composite fiber) composed of at least two types of spinnable polymers with different chemical or physical properties. Furthermore, an ultra-fine fiber bundle is a bundle formed by the aggregation of a plurality of ultra-fine fibers.

From the perspective of achieving artificial leather with less elasticity and a softer texture, the ultrafine fibers in this embodiment are preferably long fibers. In this specification, "long fiber" refers to continuous fibers rather than short fibers intentionally cut after spinning. More specifically, it refers to filaments or continuous fibers rather than short fibers intentionally cut to a length of approximately 3–80 mm. The fiber length of the island-type composite fiber before ultrafine fiberization is preferably 100 mm or more, and more preferably 200 mm or more. Provided it is technically feasible to manufacture, and cutting is unavoidable during the manufacturing process, the aforementioned long fibers can be, for example, continuous fibers of several meters, hundreds of meters, several kilometers, or more, produced by spunbond spinning. Furthermore, through needle punching or surface buffing during twisting, a portion of the long fiber may sometimes be unavoidably cut into shorter fibers during the manufacturing process.

The ultrafine fibers of this embodiment contain polyester resins. Examples of polyester resins include modified PET such as polyethylene terephthalate (hereinafter also referred to as "PET"), isophthalic acid modified PET, sulfonated isophthalic acid modified PET, and cationic dyeable PET; aromatic polyesters such as polybutylene terephthalate and polyhexamethylene terephthalate; and aliphatic polyesters such as polylactic acid, polyethylene succinate, polybutylene succinate, polybutylene adipate, and polyhydroxybutyrate-polyhydroxyvalerate resins. Furthermore, in this specification, polyester resins include dicarboxylic acid monomer units and glycol monomer units. Modified PET refers to unmodified PET with ester-forming dicarboxylic acid monomer units or PET substituted with monomer units capable of substituting at least a portion of the glycol monomer units. Specific examples of modified monomer units that substitute dicarboxylic acid monomer units include units derived from terephthalic acid units such as isophthalic acid, sodium sulfonyl isophthalic acid, sodium sulfonyl naphthalene dicarboxylic acid, and adipic acid. Similarly, specific examples of modified monomer units that substitute glycol monomer units include units derived from ethylene glycol units such as butanediol and hexanediol. From the perspective of achieving artificial leather with less elasticity and a softer texture, the polyester resin of this embodiment is preferably PET. Furthermore, from the perspective of recyclability and achieving artificial leather with less elasticity and a softer texture, the aforementioned PET preferably contains at least 94 mol% of dicarboxylic acid monomers, more preferably at least 95 mol%, even more preferably at least 96 mol%, and may also contain 100 mol%. Additionally, from the perspective of recyclability and achieving artificial leather with less elasticity and a softer texture, the aforementioned PET preferably contains at least 94 mol% of glycol monomers, more preferably at least 95 mol%, even more preferably at least 96 mol%, and may also contain 100 mol%.

From the perspective of sustainability and the need to suppress fiber adhesion to obtain artificial leather with less elasticity and a softer texture, the polyester resin of this embodiment is preferably unmodified PET. Furthermore, from the perspective of sustainability, the polyester resin of this embodiment is preferably recycled PET.

From the perspective of the profile-forming properties of ultra-fine fiber-producing fibers, the intrinsic viscosity of the polyester resin of this embodiment is preferably 0.63 dl/g or less, more preferably 0.625 dl/g or less, and even more preferably 0.62 dl/g or less. From the perspective of mechanical properties such as tensile strength, elongation, and tear strength, it is preferably 0.55 dl/g or more, more preferably 0.56 dl/g or more, and even more preferably 0.57 dl/g or more. Suitable ranges include preferably 0.55 to 0.63 dl/g, more preferably 0.56 to 0.625 dl/g, and even more preferably 0.57 to 0.62 dl/g. Furthermore, the aforementioned "inherent viscosity" is the value measured using a phenol/tetrachloroethane (volume ratio 1/1) mixed solvent at a measurement temperature of 30°C using an Ubbelohde viscometer, specifically measured according to the procedure described in the embodiments.

The ultrafine fibers of this embodiment may contain resins other than polyester resins, or they may not contain any. Examples of resins other than polyester resins include nylon 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. From a recyclability perspective, ultrafine fibers are preferably free of resins other than polyester resins.

The resin constituting this embodiment, which has extremely fine fibers, may contain various additives, to the extent that it does not impair the effects of the invention. Examples of additives include catalysts, colorants, heat resistant agents, flame retardants, lubricants, antifouling agents, fluorescent whitening agents, matting agents, gloss modifiers, antistatic agents, fragrances, deodorants, antibacterial agents, anti-mite agents, and inorganic microparticles.

From the perspective of achieving artificial leather with less elasticity and a softer texture, the average diameter of the ultrafine fibers in this embodiment is preferably 7.5 μm or less, more preferably 6.0 μm or less, especially preferably 5.5 μm or less, and even more preferably 5.0 μm or less. There is no particular limitation on the lower limit, but from the viewpoint of ease of manufacturing and color development, it can be 1.0 μm or more, or 1.5 μm or more. Suitable ranges include preferably 1.0 to 7.5 μm, more preferably 1.0 to 6.0 μm, especially preferably 1.0 to 5.5 μm, and even more preferably 1.5 to 5.0 μm.

From the perspective of achieving artificial leather with less elasticity and a softer texture, 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 manufacturing and color rendering, it may be 0.01 dtex or more, or 0.02 dtex or more. Suitable ranges include preferably 0.01 to 0.50 dtex, more preferably 0.01 to 0.40 dtex, and even more preferably 0.02 to 0.30 dtex. Furthermore, the aforementioned "average diameter" and "average fineness" are values calculated based on the cross-sectional area measured for a randomized plurality of ultrafine fibers in a magnified photograph of the cross-section of the ultrafine fibers, specifically measured according to the procedure described in the embodiments.

<Polymer Elastomer> The artificial leather of this embodiment may or may not contain a polymer elastomer. Any polymer elastomer previously used in artificial leather can be used. Specific examples include polyurethane elastomers, acrylonitrile elastomers, olefin elastomers, polyester elastomers, and acrylic elastomers, with polyurethane elastomers and acrylic elastomers being preferred. As a polyurethane elastomer, examples 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 ester glycol, and polyisocyanate as the main component, and polyisocyanates selected from aromatic, alicyclic, and aliphatic diisocyanates such as 4,4'-diphenylmethane diisocyanate, isoflavone diisocyanate, and hexamethylene diisocyanate as the main component, and low molecular weight compounds with two or more active hydrogen atoms such as ethylene glycol and ethylenediamine combined in a specific molar ratio, and polymerized in one or more stages by melt polymerization, block polymerization, solution polymerization, etc., to obtain various polyurethane elastomers. The content of polymer polyol in polyurethane elastomer is preferably 15-90% by mass.

Furthermore, examples of acrylic elastomers include those whose homopolymers have a glass transition temperature in the range of -90 to -5°C, preferably non-crosslinked monomers, such as at least one type of soft component selected from the group consisting of methyl acrylate, n-butyl acrylate, isobutyl acrylate, isopropyl acrylate, n-hexyl (meth)acrylate, and 2-ethylhexyl (meth)acrylate, and whose homopolymers have a glass transition temperature in the range of 50 to 250°C, preferably non-crosslinked monomers, such as methyl methacrylate, ethyl methacrylate, isopropyl methacrylate, isobutyl methacrylate, and cyclohexyl methacrylate. Various acrylic elastomers are obtained by polymerizing at least one type of hard component from the group consisting of ethylene glycol di(meth)acrylate and (meth)acrylate with a monofunctional or polyfunctional ethylene unsaturated monomer unit capable of forming a crosslinking structure, or with an ethylene unsaturated monomer unit introduced into a polymer chain, such as various acrylic elastomers obtained by polymerizing an ethylene unsaturated monomer formed from at least one type of crosslinking-forming component selected from the group consisting of ethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, polyethylene glycol di(meth)acrylate, and 1,4-butanediol di(meth)acrylate.

Artificial leather made using polyurethane elastomers as the main polymer elastomer offers an excellent balance of texture and mechanical properties. Furthermore, with appropriate selection of the type, it is also superior in terms of durability. Artificial leather made using acrylic elastomers, compared to polyurethane elastomers, has lower adhesion to extremely fine fiber bundles. Therefore, the pile fixation effect during pile formation is insufficient, making it unsuitable for forming pile artificial leather. However, because the degree of hardening of the texture is suppressed relative to the content, it is particularly good for forming grain-textured artificial leather. As a polymer elastomer, it can be mixed to contain different types, or it can be divided into multiple parts to contain different types. In addition to polymer elastomers with polyurethane elastomers, acrylonitrile elastomers, olefin elastomers, polyester elastomers, acrylic elastomers, etc. as the main components, it can also contain polymer elastomer compositions with polymer elastomers such as synthetic rubber added as needed.

When the artificial leather of this embodiment contains a polymer elastomer, from the viewpoint of obtaining artificial leather with excellent texture, the content of the polymer elastomer in the artificial leather is preferably 5-45% by mass, more preferably 7-40% by mass, and even more preferably 8-30% by mass.

<Other Components> The artificial leather of this embodiment may or may not contain components other than ultrafine fibers and polymeric elastomers. Examples of such other components include those contained in the aforementioned ultrafine fibers or various additives that can be added to the polymeric elastomer fluid used for impregnation with the aforementioned polymeric elastomer. These other components may be contained in at least one of the ultrafine fibers and the polymeric elastomer. The content of these other components, which facilitates the realization of the desired effects caused by these other components and, from the viewpoints of water absorption, water repellency, and stain resistance, is preferably 0.5 to 10.0% by weight, more preferably 1.0 to 5.0% by weight, and even more preferably 1.5 to 3.0% by weight, relative to the mass of the artificial leather.

[Manufacturing Method of Artificial Leather] From the viewpoint of obtaining artificial leather with less elasticity and a softer texture, the artificial leather of this embodiment is preferably manufactured by a manufacturing method having the following steps (1) to (4), wherein the ratio (Y/X) of the strength X of the yield point of the fiber web prepared in step (1) to the maximum strength Y after the yield point is 4.0 or less. Step (1): The step of preparing a fiber web formed from ultra-fine fiber-producing fibers. Step (2): The step of forming a twisted fiber sheet using the aforementioned fiber web. Step (3): The step of shrinking the aforementioned twisted fiber sheet to remove at least one component from the aforementioned ultra-fine fiber-producing fibers, thereby obtaining an artificial leather matrix. Step (4): The step of dyeing the aforementioned artificial leather matrix.

The manufacturing method of this embodiment easily obtains the artificial leather of this embodiment by having a fiber web with a ratio (Y/X) of 4.0 or less of the strength X at the prepared lateral yield point to the maximum strength Y after the yield point (step (1)). The steps are explained below.

<Step (1)> Step (1) is the step of preparing a fiber web formed from ultrafine fiber-producing fibers. As mentioned above, ultrafine fiber is a fiber produced by removing at least one component from a multi-component system fiber (composite fiber) made of at least two types of spinnable polymers with different chemical or physical properties. The multi-component system fiber that produces the ultrafine fiber is an ultrafine fiber-producing fiber. Representative examples of ultra-fine fiber-producing fibers include island-type composite fibers, multi-layered composite fibers, and radially layered composite fibers, which are obtained by methods such as fragment blending (mixed spinning) or composite spinning. Among these, from the viewpoint of improving productivity through high-speed spinning and obtaining artificial leather with excellent surface abrasion resistance and turgor resistance, island-type composite fibers are preferred. From the same viewpoint, it is preferable to obtain a fiber web by melt spinning island-type composite fibers. When the ultrafine fiber producing type is an island-type composite fiber, the island component is dispersed in the sea component that forms the matrix in the fiber cross-section. By removing the sea component, a bundle-like ultrafine fiber is produced. The following describes in more detail the method of obtaining a fiber web by melt spinning the island-type composite fiber using it as the ultrafine fiber producing type.

The resins containing the island components (described later as ultrafine fibers) in island-type composite fibers can be the same resins used in the ultrafine fibers constituting the aforementioned "ultrafine fibers". Preferably, the resins containing the marine components of the island-type composite fibers, which are removed through extraction or decomposition, are resins with different solubility or decomposability and low compatibility with the island component resins. Such resins are preferably selected according to the type or manufacturing method of the island component resin. Resins that are marine components include, for example, olefinic resins such as polyethylene, polypropylene, ethylene-propylene copolymer, and ethylene-vinyl acetate copolymer, or resins such as polystyrene, styrene-acrylic acid copolymer, and styrene-ethylene copolymer, which are soluble in organic solvents and can be removed by organic solvents. Also included are resins that can be removed with water alone without the use of solvents, such as polyvinyl alcohol resins, water-soluble polyester resins, easily alkali-degradable modified polyester resins, polyacrylamide resins, and carboxymethyl cellulose resins. Among these, from the viewpoints 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 even more preferred.

From the perspectives of copolymerization properties, melt spinning properties, and fiber water solubility, the preferred types of copolymer monomers used in modified polyvinyl alcohol (PVA) 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. The copolymer monomer content in PVA is preferably 1–20 mol%, more preferably 4–15 mol%, and even more preferably 6–13 mol%. Furthermore, if the copolymer monomer is ethylene, the fiber properties become higher; therefore, ethylene-modified PVA is more preferred. The ethylene monomer content in ethylene-modified PVA is preferably 4–15 mol%, and even more preferably 6–13 mol.

There is no particular limitation on the mass ratio of sea component to island component in island-type composite fibers, but a range of sea component: island component = 5:95 to 80:20 is preferred. If the sea component polymer ratio 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, thus ensuring industrial productivity. Furthermore, when imparting a polymer elastomer, after removing the sea component, the required size of gaps can easily form between the extremely fine fiber bundles and the polymer elastomer, resulting in a fluffy or full feel, and a dense surface texture. On the other hand, if the sea component polymer ratio is 80% by mass or less, the shape or distribution of the island component in the cross-section of the island-type fiber is stable, making it easier to prevent a decrease in quality stability.

As a method for manufacturing fiber webs, it is preferable to use a method that involves gathering extremely fine fiber-generating fibers produced by melting and spinning using a so-called spunbond method onto a conveyor belt without cutting them, thereby forming a fiber web of long fibers as continuous fibers.

Specifically, by using a composite spinning nozzle with multiple nozzles arranged in a specific pattern, molten strands of island-type composite fibers are continuously ejected from the spinning nozzle at a specific ejection speed. At any stage from directly below the nozzle orifice to the suction device described later, the fibers are substantially cooled and solidified by cooling air, while a suction device such as an air-jet nozzle is used to apply high-speed airflow, uniformly drawing and refining the island-type composite fibers to the desired diameter or fineness. The high-speed airflow system can operate at any speed within the range of 1,000 to 6,000 m/min, equivalent to the average spinning speed of mechanical traction in conventional spinning. Furthermore, a fiber web can be manufactured by a spinning and bonding method in which, while the island-type composite fibers are opened by an impact plate or airflow according to the texture of the resulting fiber web, the airflow simultaneously attracts and traps the fibers from the opposite side of a conveyor belt moving longitudinally, forming a long fiber web. From the viewpoint of efficiently obtaining the effects of this invention, the distance between the air nozzle and the trapping surface is preferably 10 to 100 cm. More preferably, it is 30 to 80 cm, and even more preferably, it is 40 to 70 cm. The suction speed towards the trapping surface is preferably 5–35 m/s, more preferably 10–25 m/s. Furthermore, the moving speed of the trapping surface is preferably 20–150 m/min, more preferably 50–120 m/min. By adjusting the average spinning speed, the distance between the nozzle and the trapping surface, the suction speed towards the trapping surface, and the moving speed of the trapping surface, the expansion or cross-linking of the island-type composite fibers trapped on the trapping surface can be appropriately adjusted. As a result, artificial leather with less elasticity and a softer texture can be obtained.

In the process of preparing the fiber web, the greater the expansion of the island-type composite fibers captured on the capture surface of the conveyor belt, the greater the number of inter-fiber crossings. A higher number of inter-fiber crossings also causes the entangled fiber sheet to shrink. When removing at least one component from the ultra-fine fiber-producing type of fiber, the residual strain coefficient accompanying longitudinal elongation becomes higher, making it difficult to elongate in the transverse direction, thus increasing the area ratio A. Furthermore, the smaller the expansion upon landing on the belt, the fewer the number of inter-fiber crossings. The fewer the number of inter-fiber crossings, the easier it is for the fiber to unravel moderately as it elongates in the longitudinal direction when at least one component is removed from the extremely fine fiber-producing fiber. Residual strain is less likely to remain, and it is easier to elongate in the transverse direction, thus reducing the area ratio A.

To give the fiber web shape stability, it can be hot-pressed or welded.

If the ratio (Y/X) of the strength X at the yield point in the transverse direction of the fiber web obtained in step (1) to the maximum strength Y after the yield point is 4.0 or less, then the number of fiber crosses becomes appropriate, and it is easy to obtain the artificial leather of this embodiment. In step (3), such a fiber web, in addition to the transverse (width) shrinkage and the tension of the transverse fibers is relaxed, also has the longitudinal fibers appropriately unwound so that the tension in the longitudinal direction can also be relaxed, and the thickness is also suppressed, the apparent density is not easy to increase, and it is easy to obtain artificial leather with a soft texture. From the viewpoint of obtaining artificial leather with less elasticity and a softer texture, Y/X is preferably 3.9 or less.

<Step (2)> Step (2) is the step of forming a twisted fiber sheet using the aforementioned fiber web. Step (2) is the step of obtaining a twisted web formed by twisting long fibers in the thickness direction by applying a twisting treatment such as needle punching or water flow intertwining after the fiber web obtained in step (1) is overlapped multiple times. As a method of overlapping multiple fiber webs, the fiber webs can be overlapped entirely in the same direction, or the transport direction of the fiber webs can be changed to a 90° direction by cross-laying and folding back and overlapping. The method of overlapping multiple fiber webs allows for easy and arbitrary adjustment of the width of the twisted fiber sheets, suppressing unevenness in the width direction of the fiber web. In other words, from the perspective of uneven weight per unit area, cross-laying is preferred. There is no particular limitation on the number of layers of the overlapped web, but from the perspective of mechanical strength, 4 or more layers are preferred, more preferably 8 or more layers. From the perspective of ease of manufacturing, 20 or fewer layers are preferred, more preferably 16 or fewer layers.

In a fiber web that has been stacked multiple times, mechanical entanglement is applied using well-known methods such as needle punching or high-pressure water jet treatment, so that the fibers constituting the fiber web are three-dimensionally entangled with each other, especially the fibers between adjacent layers of a layered fiber web that has been laid or stacked. When performing the binding process using the needle-punching method, various processing conditions should be selected, including the type of needle (needle shape or size, barb shape or depth, number or position of barbs, etc.), the number of needle punctures (the needle-punching density per unit area, obtained by multiplying the density of needles on the needle plate by the number of strokes per unit area that cause the plate to act on the fiber web), and the needle puncture depth (the depth to which the needle acts on the fiber web). In the step of obtaining the artificial leather matrix, when the components removed from the ultra-fine fiber-producing fibers are water-soluble polymers, it is preferable to perform the binding process using the needle-punching method to inhibit the dissolution of water-soluble polymers during the binding process.

From the perspective of easily obtaining high abrasion resistance, the puncture density for needle puncture treatment is preferably 1500–5500 punctures/ ^cm² , and more preferably 2000–5000 punctures/ ^cm² . If the puncture density is within the above range, insufficient knotting can be suppressed, as well as the rough surface caused by fiber abrasion on the surface of artificial leather can be suppressed, and fiber cutting can be suppressed to prevent a decrease in knotting strength.

Furthermore, at any stage from the spinning of island-type composite fibers to the twisting process, oils or antistatic agents can be applied to extremely fine fiber-generating fibers, fiber webs, fiber web laminates, twisted fiber sheets, etc. Moreover, if necessary, the twisting state of the fiber web can be pre-densified by immersing the extremely fine fiber-generating fibers, fiber webs, fiber web laminates, twisted fiber sheets, etc., in warm water at approximately 70–150°C for shrinkage treatment.

The unit area weight of the twisted fiber sheet is preferably in the range of approximately 100–1000 g/ ^m² . Furthermore, the fiber density and twist strength can be further increased by thermally shrinking the twisted fiber sheet as needed. Additionally, to further densify the already compacted twisted fiber sheet through thermal shrinkage, and to fix the shape of the twisted fiber sheet or smooth the surface, hot pressing can be performed as needed to further increase the fiber density.

<Step (3)> Step (3) involves shrinking the aforementioned twisted fiber sheet to remove at least one component from the aforementioned ultrafine fiber-producing fiber, thereby obtaining the artificial leather matrix. The aforementioned component is preferably a resin containing marine components found in island-type composite fibers. By removing the marine components, the ultrafine fiber-producing fiber can be converted into an ultrafine fiber bundle.

Methods for shrinking twisted fiber sheets include heat shrinkage treatments (fiber shrinkage treatments) such as applying steam, hot water, or dry heat. When twisted fiber sheets are subjected to heat shrinkage treatment, in addition to shrinking in the transverse (width) direction and easing transverse fiber tension, the longitudinal fibers also loosen appropriately during the removal of at least one component, thus easing longitudinal tension and suppressing the increase in apparent density. As a result, artificial leather with less elasticity and a softer texture can be obtained.

Methods for removing marine components from resins include, for example, using solvents or decomposing agents that selectively remove only the marine components. When the marine components are water-soluble resins such as polyvinyl alcohol resins, water-soluble polyester resins, easily alkali-degradable modified polyester resins, polyacrylamide resins, and carboxymethyl cellulose resins, the marine components can be removed with water. When the marine components are insoluble in water but soluble in organic solvents, and the marine component resin is a polyacrylamide resin or a polyester resin, examples of organic solvents for dissolving and removing the marine components include toluene, trichloroethylene, and tetrachloroethylene. In this embodiment, from an environmentally friendly perspective, water is preferred, and for resins that are poorly soluble in water, toluene, which has high resin solubility, is preferred.

From the perspective of efficiently achieving the effects of this invention, it is preferable to simultaneously perform the shrinkage of the twisted fiber sheet and the removal of at least one component from the aforementioned ultra-fine fiber-producing fibers. When the sea component is a water-soluble resin, it is preferable to use hot water to shrink the twisted fiber sheet and remove the water-soluble resin. Furthermore, when removing the sea component, dip-nip processing can also be performed concurrently.

<Step (4)> Step (4) is the step of dyeing the aforementioned artificial leather substrate. Step (4) can be performed at any stage after the island-type fibers are transformed into extremely fine fiber bundles.

In step (4), dyes suitable for the type of fiber, such as disperse dyes, reactive dyes, acid dyes, metallic ochre dyes, sulfur dyes, and sulfur dyeing dyes, are used. Dyeing methods commonly used in the dyeing of artificial leather, such as padders, jiggers, circular dyeing machines, and wince machines, can be adopted. On the other hand, artificial leather dyed by hot melt dyeing in the past has the problem of strong elasticity and poor softness. However, artificial leather substrates manufactured using the aforementioned steps (1) to (3), where the ratio (Y/X) of the strength X at the yield point of the fiber web prepared in step (1) to the maximum strength Y after the yield point is 4.0 or less, can produce artificial leather with low elasticity and a soft texture even when dyed using hot melt dyeing. Furthermore, compared to dyeing methods used for conventional artificial leather, hot melt dyeing significantly reduces water usage and thus lowers environmental impact. Therefore, from the perspective of reducing environmental impact, it is preferable to dye the artificial leather substrate using hot melt dyeing.

<Step (5)> From the viewpoint of imparting a texture or morphological stability close to that of natural leather, the manufacturing method of this embodiment of artificial leather can further include step (5) of impregnating the aforementioned polymer elastomer into the aforementioned twisted fiber sheet. Step (5) can be performed between steps (2) and (3), or between steps (3) and (4). In the manufacturing of this embodiment of artificial leather, in order to impart a texture or morphological stability close to that of natural leather, and at the same time impart softness, step (5) is preferably performed between steps (2) and (3). That is, it is preferable to impregnate the polymer elastomer before removing the sea component. In this way, by impregnating the fibers with a polymer elastomer before removing the sea components, gaps formed between the extremely fine fibers that have been removed after the sea components are removed are created. As a result, the extremely fine fibers inside the fiber bundles become difficult to restrain by the polymer elastomer, meaning that the extremely fine fiber bundles are not easily affected by the polymer elastomer, making it easier to obtain artificial leather with excellent softness. Furthermore, after removing the marine components from the island-type composite fibers, when the extremely fine fibers forming the fiber bundles are impregnated with polymer elastomers, the polymer elastomers penetrate into the gaps of the fiber bundles, and the extremely fine fibers forming the fiber bundles are restrained by the polymer elastomers, making it easy to obtain artificial leather with a hard texture.

When applying the aforementioned polymeric elastomer to the aforementioned twisted fiber sheet, a non-aqueous polymeric elastomer fluid prepared by dissolving or dispersing the polymeric elastomer in a solvent can be used, or an aqueous polymeric elastomer fluid prepared by dispersing the polymeric elastomer together with a dispersant in an aqueous medium as needed can be used. In the former case, it is easier to obtain a uniform polymeric elastomer fluid, while in the latter case, it is easier to reduce the amount of organic solvent used.

The concentration of the polymeric elastomer fluid, that is, the content of polymeric elastomers in the polymeric elastomer fluid, is preferably 0.1% to 60% by mass. Within the range that does not impair the properties of the final artificial leather, various additives such as colorants (dyes or pigments), coagulation regulators, antioxidants, ultraviolet absorbers, fluorescent agents, antifungal agents, penetrants, defoamers, lubricants, water-repellents, oil-repellents, tackifiers, bulking agents, hardening accelerators, foaming agents, and water-soluble polymers such as polyvinyl alcohol or carboxymethyl cellulose can be appropriately added to the polymeric elastomer fluid.

The details of the polymer elastomer used in step (5) are as described in the “Polymer Elastomer” column above.

Polymer elastomers can be fixed within spun fiber sheets by impregnating them with the elastomers and then solidifying them using conventional dry or wet methods. The dry method mentioned here refers to all methods that remove solvents or dispersants through drying or similar means, thereby fixing the elastomers within the fiber sheet structure. Furthermore, the wet method mentioned here refers to all methods that use a non-solvent or coagulant of polymer elastomer to treat a twisted fiber sheet structure impregnated with polymer elastomer fluid, or use an aqueous polymer elastomer fluid with added thermosensitive gelling agents to heat the impregnated twisted fiber sheet, thereby temporarily or completely fixing the polymer elastomer within the twisted fiber sheet structure before removing the dispersant.

Even without polymer elastomers, the artificial leather of this embodiment has a texture close to that of natural leather, therefore it is preferable that it is not impregnated with polymer elastomers. That is, it is preferable that step (5) is not included.

In addition to the aforementioned steps (1) to (5), as needed, the following finishing processes may also be performed: dry mechanical kneading, wet relaxation using a dyeing machine or washing machine, softener treatment, functional treatment with flame retardants or antibacterial agents, deodorants, water-repellent and oil-repellent agents, tactile modifier treatment with polysiloxane resins or silk protein-containing treatment agents, tactile modifier treatment with gripping resins, coating with colorants or enamel-textured coating resins, and design finishing treatment with resins other than the aforementioned resins.

The artificial leather of this embodiment is manufactured in the same way as conventional artificial leather. As needed, it can be cut into multiple pieces in the thickness direction, ground into the back side, etc., to adjust the thickness. Alternatively, the back side can be coated with a solvent that can dissolve or swell polymer elastomers or extremely fine fiber bundles.

The artificial leather of this embodiment may have a napped surface. In forming the napped surface, any of the well-known methods such as sanding with sandpaper or needle cloth, or brushing, may be used. Furthermore, before or after such napping, a solvent capable of dissolving or swelling the polymer elastomer or extremely fine fiber bundles may be applied to the napped surface. For example, if the polymer elastomer is a polyurethane elastomer, a treatment solution containing dimethylformamide (DMF) or a treatment solution containing phenolic compounds such as resorcinol may be applied. This allows for fine adjustment of the constraint state of the ultrafine fiber bundles caused by the attachment of polymer elastomers or ultrafine fiber bundles, the ultrafine fiber pile length of the artificial leather, and surface friction durability. Furthermore, after the above-mentioned napping treatment, step (4) can be performed. Example

The invention will now be explained in more detail by way of examples. Furthermore, the scope of the invention is not limited by the content of the examples.

First, the evaluation methods used in the implementation examples and comparative examples will be summarized below.

<Intrinsic viscosity> A phenol/tetrachloroethane (volume ratio 1/1) mixture was used as the solvent, and the viscosity was measured at a temperature of 30°C using an Ubbelohde viscometer "HRK-3" (manufactured by Hayashi Manufacturing Co., Ltd.).

<Expansion of island-type composite fibers on the conveyor belt (collection surface)> Island-type composite fibers were ejected for 2 seconds from the air nozzle onto the stopped conveyor belt, and the expansion (length) of the island-type composite fibers in the direction of conveyor belt drive was measured.

<Strength X at the yield point in the transverse direction of the fiber web and maximum strength Y after the yield point> After cutting out a 16cm×16cm piece from the fiber web, it was folded four times in the longitudinal direction (initially folded to become half the area, then folded to become a quarter of the area). The width of the test piece was set to 4cm. Using a precision universal testing machine (Autograph AG-X plus manufactured by Shimadzu Corporation), the tensile tester with a clamping interval of 10cm and a constant speed elongation type was used to elongate the sample at a tensile speed of 200mm/min. The SS curve showing the relationship between strength (kg) and elongation (%) was measured. From the obtained SS curve, read the strength X (kg) at the surrender point and the maximum strength Y (kg) after the surrender point (the maximum strength after the surrender point).

<Content of Polymer Elastomers> The weight C of the artificial leather cut into pieces weighing 1g or more was determined. Next, the artificial leather was immersed in hexafluoro-2-propanol (HFIP) at room temperature (25°C) for 12 hours to dissolve the polyester fibers. The remaining solid components were filtered and washed with HFIP, then dried to remove the HFIP, and the weight D of the resulting solid was determined. Then, the content of polymer elastomers in the artificial leather was calculated based on the following formula (2). Content of polymer elastomers (mass%) = D/C × 100 … Formula (2) In addition, the so-called "solid components" are the components after the solvent or dispersant has been removed.

<Average Diameter> The average diameter of the polyester fiber is determined as follows. A scanning electron microscope (SEM) image of the cross-section of the artificial leather is taken at 3000x magnification. Ten fiber cross-sections are randomly selected from the SEM image, the area of each cross-section is measured, and the arithmetic mean of the area is calculated. The result calculated based on the following formula (1) is taken as the average diameter of the fiber. Average diameter = (average area / π) ^1/2 × 2… Formula (1)

<Average Slimness> The average slimness of polyester fibers is determined as follows: A scanning electron microscope (SEM) image of the cross-section of the artificial leather is taken at 3,000x magnification. Ten fiber cross-sections are randomly selected from the SEM image, the area of each cross-section is measured, and the arithmetic mean of the area is calculated. Then, the average area is converted into the average slimness using the resin density.

<Determination of Area Ratio A and Area Ratio B> Using a single-edged razor, the artificial leather was cut along its thickness in the longitudinal direction. The resulting cross-sections were then photographed multiple times at 150x magnification from the surface to the back side using a scanning electron microscope (SEM). These multiple images were printed on paper, with the cross-sections of the artificial leather connected continuously from the surface to the back side. Straight lines were drawn so that they evenly cut across the boundary between the artificial leather substrate and the root portion of the fibers on the printed surface. Furthermore, a rectangle of approximately 400μm (depth direction) × 700μm (orthogonal to the depth direction) was drawn in the center of the cross-section of the artificial leather on the printed surface. A transparent polyethylene terephthalate (PET) film was placed on the printed surface to cover the aforementioned rectangle, and the surface of the PET film covering the rectangular portion was blackened. Using the image analysis software "Image-Pro Premier ver. 9.1" (manufactured by ROVER Co., Ltd., Japan), the area of the blackened portion of the PET film was analyzed, and the area of the longitudinal section of the artificial leather was measured. Secondly, instead of the aforementioned rectangular portion of the PET film that has been blackened, a new transparent PET film is placed on the printing surface to cover the aforementioned rectangle. The aforementioned straight line is set to 0°, and the angle (±90° or less) between the straight line and the ultra-fine fibers is set to the angle in the thickness direction. The surface of the PET film containing the ultra-fine fibers oriented in the thickness direction within the range of -30° to +30° is blackened. The aforementioned image analysis software is used in the same way as for measuring the area of the longitudinal section of the artificial leather. In the longitudinal section of the artificial leather, the area of the ultra-fine fibers oriented in the thickness direction within the range of -30° to +30° is measured. From the area of the longitudinal section of the obtained artificial leather and the area of the extremely fine fibers oriented in the thickness direction within the range of -30° to +30°, calculate the area ratio A (%) of the extremely fine fibers oriented in the thickness direction within the longitudinal section of the artificial leather. Next, in the thickness direction of the transverse section of the artificial leather, use a single-edged razor to cut it. For the resulting section, calculate the area ratio B (%) of the extremely fine fibers oriented in the thickness direction within the thickness direction within the transverse section of the artificial leather by the same operation as when calculating the aforementioned area ratio A (%).

<Thickness, Weight per Unit Area and Apparent Density> The obtained artificial leather was cut into pieces of 16cm × 16cm ( ^256cm² ). The mass (g) of the cut artificial leather was measured, and the weight per unit area (g/m²) of the cut artificial leather was calculated using the following formula ( ³ ). Weight per unit area = mass / 256 × 10000… Formula (3) According to JIS L1096 (2010) (Method A), the thickness (mm) of the cut artificial leather was measured using a thickness gauge (measuring head diameter: 10mm) under a constant pressure of 23.5kPa for 5 seconds. According to JIS K6505 (1995) 5.2.2, the apparent density (g/ ^cm³ ) of the artificial leather was calculated using the following formula (4). Apparent density = weight per unit area / thickness / 1000... Equation (4)

<Yang's Modulus> Using YAWASA (YWS-5N-1-SL) (manufactured by TECH Corporation), the artificial leather obtained from the embodiment and comparative examples were overlapped into 3 pieces. Using the front end with a pressing diameter of 1 mm, it was compressed in the thickness direction at a speed of 0.2 m/sec until the maximum pressing force of 0.2 N was reached, and the Yang's modulus was measured.

<Texture> The texture of the artificial leather after bending is judged by visual inspection and touch using the following criteria: A: It has a full feel, little elasticity, and excellent softness when bent without significant creases. B: It is equivalent to one or more of the following textures: lacking fullness, having elasticity, having significant creases, and being relatively stiff.

[Example 1] A water-soluble thermoplastic polyvinyl alcohol resin (modified polyvinyl alcohol modified by ethylene copolymerization) as the sea component and recycled polyethylene terephthalate (with 100 moles of terephthalic acid-derived structural units in the dicarboxylic acid unit) with an intrinsic viscosity of 0.60 dl/g as the island component are extruded from a melt-spun composite spinning spinneret (number of islands: 25 islands/fiber) at 270°C with a sea component/island component ratio of 25/75 (mass ratio). Next, an air jet nozzle was placed 55 cm above the conveyor belt (the trapping surface of the island-type composite fiber) to spin the fiber while simultaneously drawing and refining the edge at a spinning speed of 3279 m/min. This process replenished the island-type composite fiber with an average fineness of 3.05 dtex onto the conveyor belt, resulting in an island-type composite fiber sheet. Under the aforementioned trapping conditions, the extension (length) of the island-type composite fiber on the conveyor belt (trapping surface) was measured, yielding a length of 24.5 cm. The resulting island-type composite fiber sheet was then hot-pressed using a calendering roller at a roller surface temperature of 58°C and a linear pressure of 36 kg/cm to obtain a fiber web. The resulting fiber web has a yield strength (X) of 0.6 kg and an elongation of 6% in the transverse direction. The maximum strength (Y) after the yield point is 1.73 kg, and the elongation at the maximum strength (Y) is 190%, with Y/X = 2.9. Next, the fiber web is cross-laminated to form a laminated web. Then, the laminated web is needle-punched using a 6-barbed needle to form a longitudinally coiled twisted fiber sheet with a weight per unit area of 292 g/ ^m² . Subsequently, by simultaneously impregnating and pressing the twisted fiber sheet with high-pressure water flow treatment and immersing it in hot water at 95°C for 10 minutes, the water-soluble thermoplastic polyvinyl alcohol resin, which constitutes the marine component of the island-type composite fiber, is dissolved and removed, forming extremely fine polyethylene terephthalate fibers with an average diameter of 3.02 μm and an average fineness of 0.101 dtex. Then, the artificial leather matrix is obtained by drying. Next, the obtained artificial leather matrix is hot-melt dyed with disperse dyes and subjected to a napping treatment to obtain artificial leather with a velvety surface. The obtained artificial leather has a unit area weight of 436 g/ ^m² , an apparent density of 0.451 g/ ^cm³ , and a thickness of 0.97 mm. The resulting artificial leather has a full feel, little elasticity, and excellent softness when bent without significant wrinkles.

[Example 2] In addition to adjusting the air nozzle to obtain a sheet of island-type composite fiber by measuring the expansion of the island-type composite fiber on the conveyor belt (collecting surface) to be 26.0 cm, as in Example 1, dyed artificial leather was also obtained. The results are shown in Table 1.

[Example 3] In addition to adjusting the air nozzle to obtain a sheet of island-type composite fiber by measuring the expansion of the island-type composite fiber on the conveyor belt (collecting surface) to be 27.0 cm, as in Example 1, dyed artificial leather was also obtained. The results are shown in Table 1.

[Example 4] In addition to dyeing the artificial leather substrate by cyclic dyeing instead of hot melt dyeing as in Example 1, dyed artificial leather was also obtained. The results are shown in Table 1.

[Example 5] In addition to Example 3, where Kasesol ARS-2 (manufactured by Nichika Chemical Co., Ltd.) as an acrylic emulsion was mixed with water at a mass ratio of 30:70 (acrylic emulsion content: approximately 18% by mass), impregnated with the artificial leather substrate at a pick-up rate of 40%, dried at 140°C for 4 minutes, and then subjected to hot melt dyeing, dyed artificial leather was obtained in the same manner. The results are shown in Table 1.

[Comparative Example 1] In addition to adjusting the air nozzle to obtain a sheet of island-type composite fiber by measuring the expansion of the island-type composite fiber on the conveyor belt (collecting surface) as 23.0 cm in Example 1, dyed artificial leather was also obtained. The results are shown in Table 1.

[Comparative Example 2] In addition to using isophthalic acid-modified polyethylene terephthalate (PET modified with 6 mol% isophthalic acid) instead of recycled PET with an intrinsic viscosity of 0.60 dl/g in Example 1, and adjusting the air nozzle so that the expansion measurement result of the island-type composite fiber on the conveyor belt (collecting surface) is 27.0 cm, a sheet of island-type composite fiber was obtained, and dyed artificial leather was also obtained. The results are shown in Table 1.

[Comparative Example 3] Dyed artificial leather was obtained in the same manner as in Comparative Example 2, except that cyclic dyeing was used instead of hot melt dyeing. The results are shown in Table 1.

[Comparative Example 4] In addition to adjusting the air nozzle to obtain a sheet of island-type composite fiber by measuring the expansion of the island-type composite fiber on the conveyor belt (collecting surface) as 23.2 cm in Example 1, dyed artificial leather was also obtained. The results are shown in Table 1.

[Table 1] Implementation Example 1 Implementation Example 2 Implementation Example 3 Implementation Example 4 Implementation Example 5 Comparative example 1 Comparative example 2 Comparative example 3 Comparative example 4 sea ingredient Kind Modified polyvinyl alcohol Modified polyvinyl alcohol Modified polyvinyl alcohol Modified polyvinyl alcohol Modified polyvinyl alcohol Modified polyvinyl alcohol Modified polyvinyl alcohol Modified polyvinyl alcohol Modified polyvinyl alcohol island component Kind Polyester Polyester Polyester Polyester Polyester Polyester Modified polyester Modified polyester Modified polyester Average diameter (μm) 3.02 2.94 3.16 3.02 3.16 3.02 3.00 3.00 3.10 Average fiber thickness (dtex) 0.101 0.095 0.110 0.101 0.110 0.101 0.099 0.099 0.106 Fiber length Long fibers Long fibers Long fibers Long fibers Long fibers Long fibers Long fibers Long fibers Long fibers Expansion (cm) of island-type composite fibers 24.5 26 27 24.5 27 twenty three 27 27 23.2 Fiber web transverse strength The strength X (kg) at the surrender point 0.60 0.32 0.28 0.60 0.28 1.32 0.24 0.24 1.13 Maximum strength Y (kg) after the yield point 1.73 1.23 1.10 1.73 1.10 1.63 1.10 1.10 1.58 Y/X 2.9 3.8 3.9 2.9 3.9 1.2 4.6 4.6 1.4 Polymer elastomer Kind - - - - acrylic emulsion - - - - Contains percentage (mass %) - - - - 6.7 - - - - Staining methods Hot melt dyeing Hot melt dyeing Hot melt dyeing Cyclic staining Hot melt dyeing Hot melt dyeing Hot melt dyeing Cyclic staining Hot melt dyeing artificial leather Area ratio A (%) 3.6 2.5 0.5 4.0 3.5 7.2 6.3 5.2 6.0 Area ratio B (%) 4.5 5.3 4.1 6.9 4.7 6.9 2.1 4.1 6.8 A/B 0.8 0.5 0.1 0.6 0.8 1.0 3.0 1.3 0.88 Weight per unit area (g/ ^m² ) 436 375 436 481 465 553 484 486 500 Thickness (mm) 0.97 0.82 0.97 1.00 0.95 1.13 0.91 1.00 1.01 Apparent density (g/ ^cm³ ) 0.451 0.457 0.449 0.481 0.489 0.489 0.531 0.486 0.495 Young's modulus (kPa) 53.1 39.0 27.8 34.2 53.0 71.5 70.8 59.4 69.5 texture A A A A A B B A B

As shown in Table 1, the artificial leather obtained in Examples 1 to 5 has less elasticity and a soft texture. On the other hand, it can be seen that the artificial leather obtained from Comparative Examples 1, 2 and 4, which do not have the invention of this case, has strong elasticity and poor texture, while the artificial leather obtained from Comparative Example 3, which does not have the invention of this case, has strong elasticity.

without.

Claims (10)

An artificial leather comprising ultrafine fibers containing polyester resin, wherein in a longitudinal section of the artificial leather, the area proportion A of ultrafine fibers oriented in the thickness direction within the range of -30° to +30° is 4.5% or less, and in a transverse section of the artificial leather, the area proportion B of ultrafine fibers oriented in the thickness direction within the range of -30° to +30° is A/B ≤ 0.9. For example, the artificial leather of claim 1, wherein the average diameter of the extremely fine fibers is less than 7.5 μm. For example, the artificial leather of claim 1 or 2, wherein the average fiber density of the ultrafine fibers is less than 0.50 dtex. For example, the artificial leather in claim 1 or 2, wherein the very fine fibers are long fibers. For example, the artificial leather in claim 1 or 2, wherein the polyester resin is polyethylene terephthalate. For example, the artificial leather of claim 1 or 2, wherein the inherent viscosity of the polyester resin is less than 0.63 dl/g. For example, the artificial leather in claim 5, wherein the polyethylene terephthalate comprises dicarboxylic acid units and diol units, wherein more than 94 moles of the dicarboxylic acid units are structural units derived from terephthalic acid. For example, the artificial leather in claim 7, wherein the polyethylene terephthalate is recycled polyethylene terephthalate. A method for manufacturing artificial leather, as described in claim 1 or 2, comprising: a step of preparing a fiber web formed from ultrafine fiber-producing fibers; a step of forming a twisted fiber sheet using the fiber web; a step of shrinking the twisted fiber sheet to remove at least one component from the ultrafine fiber-producing fibers to obtain an artificial leather matrix; and a step of dyeing the artificial leather matrix; wherein the ratio (Y/X) of the yield strength X at the lateral yield point of the fiber web to the maximum strength Y after the yield point is 4.0 or less. The method for manufacturing artificial leather, as claimed in claim 9, does not impregnate with a polymer elastomer before extracting a component from the extremely fine fiber-producing fiber.