EP4749015A1

EP4749015A1 - Artificial leather, method for producing same, and use of same

Info

Publication number: EP4749015A1
Application number: EP24842865.8A
Authority: EP
Inventors: Shunichi Kimura; Norihiro Taguchi; Makoto Yamashina
Original assignee: Toray Industries Inc
Current assignee: Toray Industries Inc
Priority date: 2023-07-19
Filing date: 2024-06-17
Publication date: 2026-05-27
Also published as: WO2025018069A1; CN121358912A; JPWO2025018069A1; KR20260040157A; JP7648011B1

Abstract

An artificial leather comprising: a fibrous base material composed of a nonwoven fabric and a woven fabric entangled and integrated together; and a polyurethane having a hydrophilic group, wherein
the nonwoven fabric is composed of polyester ultrafine fibers having an average single fiber diameter of 0.1 µm or more and 10.0 µm or less,
the woven fabric is composed of a multifilament having 30 or more and 300 or less filaments, and the filaments constituting the multifilament have an average single fiber diameter of 1 µm or more and 30 µm or less,
a content rate of the polyurethane in the artificial leather is 15 mass% or more and 25 mass% or less, and
a ratio of filaments to which the polyurethane is attached among outermost peripheral filaments of the multifilament is 10% or more and 80% or less. Provided are an artificial leather composed of a fibrous base material including a nonwoven fabric and a woven fabric entangled and integrated together and a water-dispersed polyurethane, the artificial leather having high strength and excellent suppleness and abrasion resistance, a method for manufacturing the same, and applications of the same.

Description

TECHNICAL FIELD

The present invention relates to an artificial leather and a method for manufacturing the same, and use of the same.

BACKGROUND ART

An artificial leather mainly composed of a fibrous base material, such as a nonwoven fabric, and polyurethane has excellent characteristics which cannot be found in natural leather, such as high durability and high uniformity. In particular, a so-called suede-like artificial leather, in which the surface is buffed to form ultrafine fiber naps, is used not only as a clothing material but also in various fields such as vehicle interior materials, furniture interior materials, and building materials. In particular, a method in which a water-dispersed polyurethane comprising a polyurethane resin dispersed in water is used has been widely investigated instead of a method in which a conventional organic solvent-based polyurethane is used as polyurethane from the viewpoint of environmental care.
When a suede-like artificial leather is used for a skin material such as a vehicle interior material, distortion may occur in the skin material due to repeated use for a long period of time. Accordingly, a method of forming an artificial leather that has high strength and can withstand use for a long period of time by entangling and integrating a woven fabric inside or on one side of a nonwoven fabric has been investigated.
However, an artificial leather in which a woven fabric is entangled and integrated inside or on one side of a nonwoven fabric is generally problematic in that the texture tends to be hard. One of the main reasons for this is that the degree of freedom of the woven fabric is lowered by strongly gripping entanglement points of the woven fabric by the polyurethane added.
In particular, when water-dispersed polyurethane is used as polyurethane, and polyurethane emulsions are aggregated by heating to be coagulated, the film structure of the polyurethane becomes a non-porous film having a high density, and therefore adhesion between a woven fabric and polyurethane becomes dense, entangled sites of the fibers constituting the woven fabric are strongly gripped, and the texture becomes significantly hard.
In view of such circumstances, some methods for obtaining an artificial leather having high strength and excellent suppleness by applying water-dispersed polyurethane to an artificial leather in which a woven fabric is entangled and integrated inside or on one side of a nonwoven fabric have been proposed.
For example, Patent Documents 1 and 2 each propose a method in which a specific amount of polyvinyl alcohol having a specific degree of saponification and a specific degree of polymerization is added to a fibrous base material, then a water-dispersed polyurethane is added, and then the polyvinyl alcohol is removed. In addition, it is described that according to this method, a sheet-shaped article that achieves an elegant appearance and a supple texture and further has good abrasion resistance can be obtained.
Patent Document 3 describes that by setting the ratio of a polyurethane resin to 100 mass% of a fiber sheet to 20 mass% or less, a supple texture can be achieved even in an artificial leather containing a scrim, which is a woven or knitted fabric, and produced using a water-dispersed polyurethane resin.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

Patent document 1: JP 2013-234409 A
Patent Document 2: WO 2014/042241 A
Patent Document 3: WO 2020/054256 A

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

In the methods disclosed in Patent Documents 1 and 2, polyvinyl alcohol added before polyurethane is added coats the woven or knitted fabric, and the polyvinyl alcohol is removed after the addition of the polyurethane, so that the polyurethane and the woven or knitted fabric are prevented from direct adhesion to each other, and a supple texture is achieved. However, a polyvinyl alcohol elution treatment is required, so that there is room for improvement in production efficiency.
In the method disclosed in Patent Document 3, since the amount of polyurethane added is small, it is hard to say that the method satisfies the level required by the market from the viewpoint of abrasion resistance.
Accordingly, in view of the above problems, an object of the present invention is to provide an artificial leather containing a fiber-tangled body composed of a nonwoven fabric and a woven fabric as a constituent component, the artificial leather being manufactured by an environmentally friendly process without using an organic solvent and having both a supple texture and excellent abrasion resistance, and a method for manufacturing the artificial leather.

SOLUTIONS TO THE PROBLEMS

In order to solve the above-mentioned problem, the present invention has the following configuration. That is:

[1] An artificial leather comprising: a fibrous base material composed of a nonwoven fabric and a woven fabric entangled and integrated together; and a polyurethane having a hydrophilic group, wherein
- the nonwoven fabric is composed of polyester ultrafine fibers having an average single fiber diameter of 0.1 µm or more and 10.0 µm or less,
- the woven fabric is composed of a multifilament having 30 or more and 300 or less filaments, and the filaments constituting the multifilament have an average single fiber diameter of 1 µm or more and 30 µm or less,
- a content rate of the polyurethane in the artificial leather is 15 mass% or more and 25 mass% or less, and
- a ratio of filaments to which the polyurethane is attached among outermost peripheral filaments of the multifilament is 10% or more and 80% or less.
[2] The artificial leather according to [1], wherein the polyurethane is a polyether-based polyurethane and/or a polycarbonate-based polyurethane.
[3] A method for manufacturing the artificial leather according to [1], comprising the following steps (1) to (3) arranged in this order:
1. (1) a step of entangling and integrating a nonwoven fabric composed of ultrafine fiber-generating fibers and a woven fabric together to form a fibrous base material,
2. (2) a step of impregnating the fibrous base material with an aqueous dispersion of a polyurethane having a hydrophilic group, then coagulating the polyurethane to obtain a sheet, and obtaining a shrunk sheet having a width of 0.85L or more and 0.95L or less where a width of the fibrous base material before the impregnation is denoted by L for that obtained sheet,
3. (3) a step of generating polyester ultrafine fibers from the ultrafine fiber-generating fibers of the shrunk sheet.
[4] The method for manufacturing the artificial leather according to [3], wherein means of entanglement and integration in the step (1) is needle punching.
[5] The method for manufacturing the artificial leather according to [3] or [4], wherein a means for obtaining the shrunk sheet in the step (2) is dry heat treatment at an atmospheric temperature of 100°C or more and 180°C or less.
[6] The method for manufacturing the artificial leather according to any one of [3] to [5], wherein a means for generating the polyester ultrafine fibers in the step (3) is an alkali treatment.
[7] An automobile interior material comprising the artificial leather according to [1] or [2].
[8] An automobile component comprising the artificial leather according to [1] or [2].
[9] A seat comprising the artificial leather according to [1] or [2].

EFFECTS OF THE INVENTION

According to the present invention, an artificial leather composed of a fibrous base material including a nonwoven fabric and a woven fabric entangled and integrated together and a water-dispersed polyurethane, the artificial leather having high strength and excellent suppleness and abrasion resistance, can be obtained by a simple process.

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a cross-sectional view schematically illustrating a scanning electron microscope (SEM) photograph of a cross section of an artificial leather taken for measuring and calculating a ratio of filaments to which polyurethane is attached among outermost peripheral filaments of a multifilament.

EMBODIMENTS OF THE INVENTION

The artificial leather of the present invention is an artificial leather comprising: a fibrous base material composed of a nonwoven fabric and a woven fabric entangled and integrated together; and a polyurethane having a hydrophilic group, wherein

the nonwoven fabric is composed of polyester ultrafine fibers having an average single fiber diameter of 0.1 µm or more and 10.0 µm or less,
the woven fabric is composed of a multifilament having 30 or more and 300 or less filaments, and the filaments constituting the multifilament have an average single fiber diameter of 1 µm or more and 30 µm or less,
a content rate of the polyurethane in the artificial leather is 15 mass% or more and 25 mass% or less, and
a ratio of filaments to which the polyurethane is attached among outermost peripheral filaments of the multifilament is 10% or more and 80% or less.

Hereinafter, the constituents will be described in detail, but the present invention is not limited to the scope described below without departing from the gist of the present invention, and various modifications can be made without departing from the gist of the present invention.

[Polyester ultrafine fibers]

In the artificial leather of the present invention, the fibrous base material, which is one of the constituents, is composed of polyester ultrafine fibers having an average single fiber diameter of 0.1 µm or more and 10.0 µm or less. The term "polyester ultrafine fibers" refers to "ultrafine fibers including a polyester-based resin" described below, and the ultrafine fibers refer to "fibers having a single fiber diameter of 0.1 µm or more and 10.0 µm or less" measured and calculated by a method described below.
In the present invention, the term "polyester-based resin" refers to a resin including repeating units having a mole fraction of the polyester units of 80 mol% to 100 mol%. The same applies to those described as "···-based resin" unless otherwise specified. The polyester-based resin can be formed into artificial leather excellent in heat resistance, light resistance, and the like, and examples of the polyester-based resin include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and mixtures of these polyester resins and copolymers of these polyesters. The polyester-based resin can be obtained from, for example, a dicarboxylic acid and/or an ester-forming derivative thereof and a diol.
Examples of the dicarboxylic acid and/or the ester-forming derivative thereof used for the polyester-based resin include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, and an ester-forming derivative thereof. The ester-forming derivatives referred to in the present invention include lower alkyl esters of a dicarboxylic acid, acid anhydrides, and acyl chlorides. Specifically, methyl esters, ethyl esters, hydroxyethyl esters, and the like are preferably used. A more preferable aspect of the dicarboxylic acid and/or its ester-forming derivative used in the present invention is terephthalic acid and/or its dimethyl ester.
Examples of the diol used in the polyester-based resin include ethylene glycol, 1,3-propanediol, 1,4-butanediol, and cyclohexanedimethanol. Among them, ethylene glycol is preferably used.
The polyester-based resin can contain inorganic particles such as titanium oxide particles, a lubricant, a pigment, a heat stabilizer, an ultraviolet absorber, an electrically conductive agent, a heat storage agent, an antibacterial agent, and the like according to various purposes.
As for a cross-sectional shape of the polyester ultrafine fibers, either a round cross section or a modified cross section may be adopted. Examples of the shape of the modified cross section include an elliptical shape, a flat shape, a polygonal shape such as a triangular shape, a sector shape, and a cross shape.
In the present invention, the polyester ultrafine fibers have an average single fiber diameter of 0.1 µm or more and 10.0 µm or less. When the average single fiber diameter of the polyester ultrafine fibers is 10.0 µm or less, preferably 7.0 µm or less, and more preferably 5.0 µm or less, the artificial leather can be suppler. Furthermore, the quality of the nap can be improved. Meanwhile, when the average single fiber diameter of the polyester ultrafine fibers is 0.1 µm or more, preferably 0.3 µm or more, and more preferably 0.7 µm or more, an artificial leather excellent in color developability after dyeing in the case of performing dyeing can be obtained. Furthermore, at the time of a napping treatment by buffing, bundled polyester ultrafine fibers can be improved in ease of dispersion and ease of loosening.
The single fiber diameter and the average single fiber diameter of the polyester ultrafine fibers as referred to in the present invention are those measured and calculated by the following method, specifically, as follows.

(1) A cross section formed by cutting the obtained artificial leather in the thickness direction is observed with a scanning electron microscope (SEM, "VHX-D500/D510" manufactured by KEYENCE CORPORATION or a scanning electron microscope equivalent in performance thereto).
(2) The fiber diameter of each of any 50 polyester ultrafine fibers in the observed section is measured in three directions in each polyester ultrafine fiber cross section. It is noted that in the case of utilizing polyester ultrafine fibers having a modified cross section, first, a cross-sectional area of a single fiber is measured, and then the diameter of a circle having that cross-sectional area is calculated from the following formula. The thus-obtained diameter is defined as the single fiber diameter of the single fiber.
Single fiber diameter (µm) = (4 × (cross-sectional area (µm²) of single fiber)/π)^1/2
(3) The arithmetic average (µm) of the total 150 measurements obtained is calculated, and rounded off to one decimal place, and the resultant is regarded as the average single fiber diameter (µm) of the polyester ultrafine fibers.

[Woven fabric]

It is important that the woven fabric to be used for the artificial leather of the present invention is composed of a multifilament. As the component constituting the multifilament, a polyester-based resin or a polyamide-based resin can be used, but a polyester-based resin, which is excellent in durability and heat resistance, is preferably used.
It is important that the average single fiber diameter of the filaments constituting the multifilament is 1 µm or more and 30 µm or less. When the average single fiber diameter is set to 30.0 µm or less, more preferably 15.0 µm or less, and still more preferably 13.0 µm or less, the artificial leather is excellent in suppleness. On the other hand, when the average single fiber diameter is 1.0 µm or more, more preferably 8.0 µm or more, and still more preferably 9.0 µm or more, the shape stability of a product as an artificial leather is improved.
In the present invention, the average single fiber diameter of filaments constituting the multifilament is one determined by taking a scanning electron microscope (SEM) photograph of a cross section of the artificial leather, randomly selecting 10 filaments in the multifilament constituting the woven fabric, measuring the single fiber diameter of the filaments, calculating the arithmetic average value of the 10 filaments, and rounding off the arithmetic average value to one decimal place. It is noted that when filaments having a modified cross section are employed, as in the case of measuring and calculating the average single fiber diameter of ultrafine fibers constituting a nonwoven fabric, a cross-sectional area (µm²) of a filament is first measured, and the diameter when the cross section is assumed to be a circle, that is, the equivalent-circle diameter is calculated to determine the diameter (µm) of the filament.
It is important that the number of single fibers contained in each multifilament constituting the woven fabric, namely, the number of filaments is 30 or more and 300 or less. When the number of filaments is set to 30 or more, and more preferably 50 or more, not only the shape stability of a product as the artificial leather is improved, but also the fibers that constitute the woven fabric are less likely to be exposed on the surface of the artificial leather when the nonwoven fabric and the woven fabric are entangled and integrated together by needle punching or the like, which is preferable. On the other hand, when the number of filaments is 300 or less, more preferably 250 or less, and still more preferably 100 or less, the artificial leather is excellent in suppleness. At this time, the number of filaments of the warp and the number of filaments of the weft may be either the same or different.
Furthermore, the number of twists of the multifilament is preferably 1,000 to 4,000 T/m. When the number of twists is 4000 T/m or less, more preferably 3500 T/m or less, and still more preferably 3000 T/m or less, an artificial leather excellent in suppleness is obtained. When the number of twist is 1000 T/m or more, more preferably 1500 T/m or more, and still more preferably 2000 T/m or more, in a case where a nonwoven fabric and a woven fabric are entangled and integrated together by needle punching or the like, damage to fibers constituting the woven fabric can be prevented, and physical properties of the artificial leather are excellent, which is preferable.
The basic structure of the woven fabric may be a twill structure or a satin structure; however, a plain weave structure, in which distortion and slippage of yarn and the like are unlikely to occur, can be preferably used.
The weave density of the woven fabric is preferably adjusted such that the number of both the warp and the weft is 40 yarns/2.54 cm to 200 yarns/2.54 cm in the artificial leather. When the weave density of the woven fabric constituting the artificial leather is set to 40 yarns/2.54 cm or more, and more preferably 60 yarns/2.54 cm or less, an artificial leather excellent in shape stability can be obtained. On the other hand, when the weave density of the woven fabric constituting the artificial leather is set to 200 yarns/2.54 cm or less, and more preferably 150 yarns/2.54 cm or less, not only the texture of the artificial leather can be made supple, but also the entanglement of the fibers of the nonwoven fabric is not inhibited when the nonwoven fabric and the woven fabric are entangled and integrated together, and as a result, the falling-off of fibers of the artificial leather can be suppressed.

[Fibrous base material]

The fibrous base material used in the present invention is a material composed of the nonwoven fabric formed of polyester ultrafine fiber and the woven fabric entangled and integrated together.

[Polyurethane having hydrophilic group]

Next, the artificial leather of the present invention includes a polyurethane having a hydrophilic group as a constituent. Hereinafter, this will be further described in detail.

(1) Polyurethane having hydrophilic group

First, in the present invention, "having a hydrophilic group" means that the subject itself "has a group having active hydrogen", and examples of the group having active hydrogen include a hydroxy group, a carboxyl group, a sulfonic acid group, and an amino group, and from the viewpoint of reactivity with a crosslinking agent having a carbodiimide group described later, the polyurethane preferably has a hydroxy group or a carboxyl group.
The polyurethane having a hydrophilic group can be obtained by reacting a crosslinking agent with a polyurethane precursor obtained by reacting a polymeric polyol described below, an organic diisocyanate, and an active hydrogen component-containing compound having a hydrophilic group to form a hydrophilic prepolymer and then adding and reacting a chain extender. Hereinafter, these will be described in detail.

(1-1) Polymeric polyol

Examples of the polymeric polyol preferably used in the synthesis of the polyurethane include polyether-based polyol, polyester-based polyol, and polycarbonate-based polyol.
Examples of the polyether-based polyols include polyols obtained by addition and polymerization of a monomer such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, epichlorohydrin, or cyclohexylene using a polyhydric alcohol or a polyamine as an initiator, and polyols obtained by ring-opening polymerization of the monomer using a protonic acid, a Lewis acid, a cationic catalyst, or the like as a catalyst. Examples thereof specifically include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and copolymerized polyols obtained by combining these glycols.
Next, examples of the polyester-based polyol include polyester polyols obtained by condensing various low-molecular-weight polyols with a polybasic acid, and polyols obtained by ring-opening polymerization of lactones.
Examples of the low-molecular-weight polyols used in the polyester-based polyols include one or more selected from linear alkylene glycols such as "ethylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, and 1,10-decanediol", branched alkylene glycols such as "neopentyl glycol, 3-methyl-1,5-pentanediol, 2,4-diethyl-1,5-pentanediol, and 2-methyl-1,8-octanediol", alicyclic diols such as 1,4-cyclohexanediol, and aromatic dihydric alcohols such as 1,4-bis(β-hydroxyethoxy)benzene. Adducts obtained by adding various alkylene oxides to bisphenol A can also be used as low-molecular-weight polyols.
Examples of the polybasic acid used in the polyester-based polyols include one or more selected from the group consisting of succinic acid, maleic acid, adipic acid, glutaric acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, dodecanedicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, and hexahydroisophthalic acid.
Examples of the polycarbonate-based polyols include compounds obtained by a reaction between a polyol and a carbonate compound, such as a polyol and a dialkyl carbonate or a polyol and a diaryl carbonate.
As the polyol used in the polycarbonate-based polyols, the low-molecular-weight polyols used in the polyester-based polyols can be used. Meanwhile, as the dialkyl carbonate, dimethyl carbonate, diethyl carbonate, or the like can be used, and as the diaryl carbonate, diphenyl carbonate or the like can be used.
The polymeric polyol preferably used in the present invention preferably has a number average molecular weight of 500 or more and 5,000 or less. When the number average molecular weight of the polymeric polyol is 500 or more, and more preferably 1,500 or more, the texture of the artificial leather can be easily prevented from stiffening. When the number average molecular weight is 5,000 or less, and more preferably 4,000 or less, the strength of the polyurethane having a hydrophilic group serving as a binder can be easily maintained.

(1-2) Organic diisocyanate

Examples of the organic diisocyanate preferably used in the synthesis of the polyurethane include an aromatic diisocyanate having 6 or more and 20 or less carbon atoms (excluding carbon atoms in a NCO group; the same applies to the following), an aliphatic diisocyanate having 2 or more and 18 or less carbon atoms, an alicyclic diisocyanate having 4 or more and 15 or less carbon atoms, an araliphatic diisocyanate having 8 or more and 15 or less carbon atoms, a modified product of these diisocyanates (such as a carbodiimide-modified product, a urethane-modified product, and a uretdione-modified product), or a mixture of two or more kinds thereof.
Examples of the aromatic diisocyanates having 6 or more and 20 or less carbon atoms include 1,3- and/or 1,4-phenylene diisocyanate, 2,4- and/ 2,6-tolylene diisocyanate, 2,4'- and/or 4,4'-diphenylmethane diisocyanate (hereinafter abbreviated as MDI), 4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatobiphenyl, 3,3'-dimethyl-4,4'-diisocyanatodiphenylmethane, and 1,5-naphthylene diisocyanate, and among them, MDI, which is excellent in flexibility when used in the polyurethane having a hydrophilic group, is preferably used.
Examples of the aliphatic diisocyanates having 2 or more and 18 or less carbon atoms include ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 2,2,4-trimethylhexamethylene diisocyanate, lysine diisocyanate, 2,6-diisocyanatomethylcaproate, bis(2-isocyanatoethyl) carbonate, and 2-isocyanatoethyl-2,6-diisocyanatohexaate.
Examples of the alicyclic diisocyanates having 4 or more and 15 or less carbon atoms include isophorone diisocyanate, dicyclohexylmethane-4,4'-diisocyanate, cyclohexylene diisocyanate, methylcyclohexylene diisocyanate, bis(2-isocyanatoethyl)-4-cyclohexylene-1,2-dicarboxylate, and 2,5- and/or 2,6-norbornane diisocyanate, and among them, dicyclohexylmethane-4,4'-diisocyanate, which affords a polyurethane having a hydrophilic group excellent in durability, is preferably used.
Examples of the araliphatic diisocyanates having 8 or more and 15 or less carbon atoms include m- and/or p-xylylene diisocyanate, and α,α,α',α'-tetramethylxylylene diisocyanate.

(1-3) Active hydrogen component-containing compound having hydrophilic group

Examples of the active hydrogen component-containing compound having a hydrophilic group preferably used in the synthesis of the polyurethane include a compound containing a nonionic group and/or an anionic group and/or a cationic group and active hydrogen. The active hydrogen component-containing compound can also be used in the form of salt neutralized with a neutralizer. By using this active hydrogen component-containing compound having a hydrophilic group, the stability of the aqueous dispersion used in the method for manufacturing an artificial leather can be enhanced.
Examples of the compound having a nonionic group and active hydrogen include compounds containing two or more active hydrogen components or two or more isocyanate groups and including a side chain having a polyoxyethylene glycol group with a molecular weight of 250 to 9,000 or the like, and triols such as trimethylol propane and trimethylol butane.
Examples of the compound having an anionic group and active hydrogen include carboxyl group-containing compounds such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, and 2,2-dimethylolvaleric acid and their derivatives, sulfonic acid group-containing compounds such as 1,3-phenylenediamine-4,6-disulfonic acid and 3-(2,3-dihydroxypropoxy)-1-propanesulfonic acid and their derivatives, and salts obtained by neutralizing these compounds with a neutralizer.
Examples of the compound containing a cationic group and active hydrogen include tertiary amino group-containing compounds such as 3-dimethylaminopropanol, N-methyldiethanolamine, and N-propyldiethanolamine and their derivatives.

(1-4) Chain extender

Examples of the chain extender preferably used in the synthesis of the polyurethane include water, a low-molecular-weight diol such as ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, or neopentyl glycol, an alicyclic diol such as 1,4-bis(hydroxymethyl)cyclohexane, an aromatic diol such as 1,4-bis(hydroxyethyl)benzene, an aliphatic diamine such as ethylenediamine, an alicyclic diamine such as isophoronediamine, an aromatic diamine such as 4,4-diaminodiphenylmethane, an araliphatic diamine such as xylenediamine, an alkanolamine such as ethanolamine, hydrazine, a dihydrazide such as adipic acid dihydrazide, and a mixture of two or more kinds thereof.
Among them, preferred chain extenders are water, low molecular weight diols, and aromatic diamines, and more preferred examples thereof include water, ethylene glycol, 1,4-butanediol, 4,4'-diaminodiphenylmethane, and a mixture of two or more kinds thereof.

(1-5) Configuration of polyurethane precursor

As described above, the polyurethane precursor preferably used in the synthesis of the polyurethane is prepared by reacting the polymeric polyol, the organic diisocyanate, and the active hydrogen component-containing compound having a hydrophilic group described above to form a hydrophilic prepolymer, and then adding and reacting a chain extender.

(1-6) Crosslinking agent

As the crosslinking agent preferably used in the synthesis of the polyurethane, a crosslinking agent having, in one molecule, two or more reactive groups capable of reacting with a reactive group introduced into the polyurethane precursor can be used, and examples thereof include polyisocyanate-based crosslinking agents such as water-soluble isocyanate compounds and blocked isocyanate compounds, melamine-based crosslinking agents, and carbodiimide-based crosslinking agents. The crosslinking agents may be used singly or in combination of two or more kinds thereof.
The water-soluble isocyanate-based compound has two or more isocyanate groups in one molecule, and examples of the compound include the organic polyisocyanate-containing compounds described above. Examples of commercially available products thereof include "Bayhydur" (registered trademark) series and "Desmodur" (registered trademark) series manufactured by Bayer MaterialScience.
The blocked isocyanate-based compound is a compound having two or more blocked isocyanate groups in one molecule. The blocked isocyanate group means a group of the organic polyisocyanate compound blocked with a blocking agent such as an amine, a phenol, an imine, a mercaptan, a pyrazole, an oxime, or an active methylene. Examples of commercially available products thereof include "ELASTRON" (registered trademark) series manufactured by DKS Co. Ltd., "DURANATE" (registered trademark) series manufactured by Asahi Kasei Corp., and "TAKENATE" (registered trademark) series manufactured by Mitsui Chemicals, Inc.
Examples of an oxazoline-based crosslinking agent include compounds having two or more oxazoline groups (oxazoline skeletons) in one molecule. Examples of commercially available products thereof include "EPOCROS" (registered trademark) series manufactured by NIPPON SHOKUBAI CO., LTD.
Examples of the carbodiimide-based crosslinking agent include compounds having two or more carbodiimide groups in one molecule. Examples of commercially available products thereof include "CARBODILITE" (registered trademark) series manufactured by Nisshinbo Chemical Inc.
Among them, carbodiimide compounds, which affords a polyurethane having a hydrophilic group is particularly excellent in durability and flexibility after the reaction, is particularly preferably used.

(1-7) Configuration of polyurethane having hydrophilic group

The polyurethane having a hydrophilic group is preferably a polyether-based polyurethane containing a constituent component derived from a polyether-based polyol and/or a polycarbonate-based polyurethane containing a constituent component derived from a polycarbonate-based polyol.
The polyurethane having a hydrophilic group preferably includes a constituent component derived from a polyether-based polyol from the viewpoint of flexibility. When the polyurethane having a hydrophilic group includes the constituent component derived from a polyether-based polyol, a water-dispersed polyurethane can be obtained that has a low glass transition temperature due to the high degree of freedom of the ether linkage and is excellent in flexibility because of the weak cohesive force.
On the other hand, the polyurethane having a hydrophilic group preferably includes a constituent component derived from a polycarbonate-based polyol from the viewpoint of durability. When a polyurethane having a hydrophilic group includes the constituent component derived from a polycarbonate-based polyol, the polyurethane having a hydrophilic group can be excellent in water resistance, heat resistance, weather resistance, and mechanical properties due to the high cohesive force of the carbonate group.
The configuration of the polyurethane having a hydrophilic group can be appropriately adjusted according to required characteristics, and a polyether-based polyurethane containing a constituent component derived from a polyether-based polyol or a polycarbonate-based polyurethane containing a constituent component derived from a polycarbonate-based polyol may be used singly, or both of them may be used in combination.
In a method of confirming the constituent components of the polyurethane having a hydrophilic group (confirming that the polyurethane having a hydrophilic group contains a constituent component derived from a polyester polyol and that the polyurethane having a hydrophilic group further contains a constituent component derived from a polycarbonate polyol), the polyester constituting the artificial leather is eluted, and the insoluble matter (polyurethane having a hydrophilic group) can be analyzed by infrared spectroscopic analysis (using "FT/IR 4000 series" manufactured by JASCO Corporation or an infrared spectroscopic analyzer equivalent in performance thereto, as an analytical instrument) and pyrolysis GC/MS analysis (using "GCMS-QP5050A" manufactured by SHIMADZU CORPORATION or a pyrolysis GC/MS analyzer equivalent in performance thereto, as an analytical instrument). As a solvent capable of eluting the polyester constituting the artificial leather, m-cresol or hexafluoroisopropanol can be used, and hexafluoroisopropanol, which can be handled at room temperature, is preferably used.
The polyurethane having a hydrophilic group used in the present invention preferably has a N-acylurea linkage and/or an isourea linkage. The N-acylurea linkage and/or the isourea linkage is formed by a reaction between the hydrophilic group and the crosslinking agent having a carbodiimide group to form a crosslinked structure in the polyurethane having a hydrophilic group, and thus the durability of the polyurethane having a hydrophilic group can be enhanced.
The presence of the N-acylurea group or the isourea group in the polyurethane having a hydrophilic group can be analyzed by, for example, mapping processing such as time-of-flight secondary ion mass spectrometry (TOF-SIMS analysis) (using, for example, "TOF.SIMS 5" manufactured by ION-TOF or a TOF-SIMS analyzer equivalent in performance thereto, as an analytical instrument), or by infrared spectroscopic analysis (using, for example, "FT/IR 4000 series" manufactured by JASCO Corporation or an infrared spectroscopic analyzer equivalent in performance thereto, as an analytical instrument) of the cross section of the artificial leather.

[Artificial leather]

First, in the artificial leather of the present invention, the content rate of the polyurethane having a hydrophilic group is 15 mass% or more and 25 mass% or less. When the content rate is set to 15 mass% or more, and preferably 18 mass% or more, an artificial leather excellent in abrasion resistance is obtained. Meanwhile, when the content rate is set to 25 mass% or less, and preferably 22 mass% or less, an artificial leather having a supple texture can be obtained.
In the present invention, the content rate of the polyurethane having a hydrophilic group is measured and calculated by the following method, specifically, as follows.

(1) A test piece of 5 cm × 5 cm is cut out from the artificial leather, and the mass (M_X) of the test piece is measured.
(2) The test piece is immersed in hexafluoroisopropanol to elute polyester ultrafine fibers from the artificial leather.
(3) The insoluble component (polyurethane having a hydrophilic group) in (2) is dried with a dryer at 100°C, the mass (M_A) is measured, and then the content rate (mass%) of the polyurethane having a hydrophilic group is calculated by the following formula.
Content rate of polyurethane having hydrophilic group = (M_A/M_X) × 100.

In the present invention, it is important that polyurethane is attached to 10% or more and 80% or less of the outermost peripheral filaments of the multifilament constituting the woven fabric.
When polyurethane is attached to 10% or more, more preferably 15% or more, and still more preferably 20% or more of the outermost peripheral filaments of the multifilament, an artificial leather excellent in shape stability is obtained.
Meanwhile, when polyurethane is attached to 80% or less, more preferably 60% or less, and still more preferably 50% or less of the outermost peripheral filaments of the multifilament, an artificial leather excellent in suppleness is obtained.
In the present invention, the rate of the filaments to which the polyurethane is attached among the outermost peripheral filaments of the multifilament is measured and calculated by the following method, specifically, as follows.

(1) A scanning electron microscope (SEM) photograph of a cross section of the artificial leather is taken, and the number (N_M) of outermost peripheral filaments of a multifilament constituting the woven fabric is calculated, then the number (N_p) of filaments to which the polyurethane is attached among the outermost peripheral filaments of the multifilament is calculated, and the rate of the filaments to which the polyurethane is attached is calculated by the following formula.
Ratio (%) of filaments to which polyurethane is attached = (N_p/N_M) × 100
(2) The measurement of (1) is performed for 20 multifilaments, and the average value thereof is taken as the rate of the filaments to which the polyurethane is attached.

The artificial leather of the present invention preferably has an apparent density of 0.30 g/cm³ or more and 0.40 g/cm³ or less. When the apparent density of the artificial leather is set to 0.30 g/cm³ or more, more preferably 0.32 g/cm³ or more, and still more preferably 0.34 g/cm³ or more, the artificial leather is excellent in abrasion resistance. Meanwhile, when the apparent density is set to 0.40 g/cm³ or less, and preferably 0.38 g/cm³ or less, an artificial leather having a supple texture can be obtained.
In the present invention, the apparent density of the artificial leather is calculated using the following formula by measuring the thickness and the mass per unit area of the artificial leather using the method specified in JIS L 1913: 2010 "Test methods for nonwovens" 6.1.1 (Thickness A method) and 6.2 (Mass per unit area). Apparent density of artificial leather (g/cm³) = mass per unit area of artificial leather (g/cm²)/thickness of artificial leather (cm).
In the artificial leather of the present invention, the stiffness specified in the method A (45° cantilever method) described in "8.21 Stiffness" in JIS L 1096:2010 "Testing methods for woven and knitted fabrics" is 150 mm or less in the longitudinal direction of the sheet. When the stiffness is set within this range, an artificial leather excellent in suppleness can be obtained. When the stiffness is 150 mm or less, and more preferably 100 mm or less, a suppler artificial leather can be obtained.
The artificial leather of the present invention preferably has an abrasion loss of 30 mg or less measured when the number of abrasion times is 50000 in the Martindale abrasion test specified in "8.19.5 Method E (Martindale method)" in "8.19 Abrasion resistance and change in colour due to abrasion" in JIS L 1096: 2005 "Testing methods for woven and knitted fabrics". The abrasion loss is more preferably 25 mg or less from the viewpoint of suppressing deterioration of the appearance of the artificial leather.
Furthermore, in a Martindale abrasion test specified in "8.19.5 Method E (Martindale method)" of "8.19 Abrasion resistance and change in colour due to abrasion" in JIS L 1096:2005 "Testing methods for woven and knitted fabrics" after performing xenon irradiation specified in "7.2 Exposure method a) First exposure method" in JIS L 0843:2006 "Test methods for colour fastness to xenon arc lamp light", the artificial leather of the present invention preferably has an abrasion loss of 10 mg or less when measured at the number of abrasion times of 10,000. When the abrasion loss after xenon irradiation is 10 mg or less, an artificial leather having durability with which the artificial leather can be used for a long period of time in a site exposed to sunlight such as an automobile seat is obtained.

[Method for manufacturing artificial leather]

The method for manufacturing an artificial leather of the present invention is a method for manufacturing an artificial leather including the following steps (1) to (3) in this order:

(1) a step of entangling and integrating a nonwoven fabric composed of ultrafine fiber-generating fibers and a woven fabric together to form a fibrous base material,
(2) a step of impregnating the fibrous base material with an aqueous dispersion of a polyurethane having a hydrophilic group, then coagulating the polyurethane to obtain a sheet, and obtaining a shrunk sheet having a width of 0.85L or more and 0.95L or less where the width is denoted by L for that obtained sheet,
(3) a step of generating polyester ultrafine fibers from the ultrafine fiber-generating fibers of the shrunk sheet.

The details thereof will be described below.

In this step, a nonwoven fabric composed of ultrafine fiber-generating fibers and a woven fabric are subjected to a treatment for entanglement to form a fibrous base material.
As the ultrafine fiber-generating fibers, islands-in-the-sea composite fibers are preferably used in which two components (two or three components in a case where the island fibers are core-sheath composite fibers) of thermoplastic resins having different solvent solubility are used as a sea component and an island component and the sea component is dissolved and removed using a solvent or the like to form island components as ultrafine fibers, from the viewpoint of the texture and the surface appearance of the artificial leather, because appropriate gaps can be added between the island components, that is, between the ultrafine fibers inside the fiber bundle when the sea component is removed.
The islands-in-the-sea composite fibers are preferably obtained by a method of using an islands-in-the-sea composite spinneret and using an alternately arranged polymer in which two components of a sea component and an island component (three components in a case where the island fibers are core-sheath composite fibers) are alternately arranged and spun, from the viewpoint of obtaining ultrafine fibers having a uniform single fiber diameter.
As the sea component of the islands-in-the-sea composite fibers, polyethylene, polypropylene, polystyrene, a copolymerized polyester obtained by copolymerizing sodium sulfoisophthalic acid, polyethylene glycol, or the like, polylactic acid, or the like can be used, and from the viewpoints of a yarn-making property, easy elution, and the like, polystyrene or a copolymerized polyester is preferably used.
The mass ratio between the sea component and the island component in the islands-in-the-sea composite fibers preferably used in the present invention is preferably in a range of sea component : island component = 10 : 90 to 80 : 20. When the mass ratio of the sea component is 10 mass% or more, the island component tends to be sufficiently ultrafine. When the mass ratio of the sea component is 80 mass% or less, the proportion of the eluted component is small and therefore the productivity is improved. The mass ratio between the sea component and the island component is more preferably in a range of sea component : island component = 20 : 80 to 70 : 30.
As the nonwoven fabric constituting the fibrous base material, either a staple fiber nonwoven fabric or a filament fiber nonwoven fabric can be used as described above, and a staple fiber nonwoven fabric is preferably used because the number of fibers oriented in the thickness direction of the artificial leather is larger than that in the case of using a filament fiber nonwoven fabric and thus highly dense feeling can be obtained on the surface of the napped artificial leather.
In the case of using a staple fiber nonwoven fabric as the fibrous base material, the obtained ultrafine fiber-generating fibers are preferably crimped and cut into a predetermined length to afford raw stock. The crimping and the cutting can be performed using known methods.
Next, the obtained raw stock is formed into a fiber web with a cross lapper or the like. Then, the obtained fiber web is entangled to afford a nonwoven fabric. As the method of entangling a fiber web to obtain a nonwoven fabric, needle punching, water jet punching, or the like can be used, and needle punching, which has high entanglement efficiency, is preferably performed.
Furthermore, the obtained nonwoven fabric and a woven fabric are layered, and entangled and integrated together. For the entanglement and integration of the nonwoven fabric and the woven fabric, the woven fabric can be layered on one surface or both surfaces of the nonwoven fabric, or fibers of the nonwoven fabric and the woven fabric can be entangled by needle punching, water jet punching, or the like after the woven fabric is sandwiched between a plurality of nonwoven fabric webs, and it is preferable from the viewpoint of production efficiency that woven fabrics are layered on both surfaces of the nonwoven fabric, and then the woven fabrics and the nonwoven fabric are needle punched.
The fibrous base material including the nonwoven fabric composed of the composite fibers after the treatment for entanglement (ultrafine fiber-generating fibers) and the woven fabric preferably has an apparent density of 0.20 g/cm³ or more and 0.30 g/cm³ or less. When the apparent density is 0.20 g/cm³ or more, and more preferably 0.23 g/cm³ or more, the fibrous base material has sufficient shape stability and dimensional stability. Meanwhile, when the apparent density is 0.30 g/cm³ or less, and more preferably 0.28 g/cm³ or less, a sufficient space can be maintained for adding the polyurethane having a hydrophilic group.
The fibrous base material may be subjected to a heat shrinking treatment with warm water or steam in order to improve the dense feeling of fibers, but in the present invention, since the fibrous base material is impregnated with an aqueous dispersion containing a polyurethane precursor, followed by a shrinking treatment of a sheet, it is preferable not to perform the shrinkage treatment before impregnating the fibrous base material with the aqueous dispersion containing the polyurethane precursor.

In this step, the fibrous base material is impregnated with an aqueous dispersion containing a polyurethane precursor, and then a heating and drying treatment is performed to form an impregnated sheet including a fibrous base material and a polyurethane having a hydrophilic group as constituents, and then a shrunk sheet having a width of 0.85L or more and 0.95L or less where the width of the fibrous base material before impregnation of the sheet is L is obtained.
In the method for manufacturing an artificial leather of the present invention, the coagulation after the addition of the aqueous dispersion can be conducted by applying a coagulation method commonly used in the art, such as a dry heat coagulation method or a coagulation in liquid method. In the case of using a dry heat coagulation method, the aqueous dispersion is added to the fibrous base material and then dry-coagulated by a heat treatment at a temperature of 120°C or more and 180°C or less, and thus a polyurethane having a hydrophilic group is preferably added to the fibrous base material. As the coagulation in liquid method, an acid coagulation method in which a coagulation treatment is performed with a coagulation solvent having a pH of 1 or more and 3 or less, a hot water coagulation method in which a coagulation treatment is performed with hot water having a temperature of 80°C or more and 100°C or less, or the like can be used.
The concentration of the polyurethane precursor in the aqueous dispersion (the content of the polyurethane precursor in 100 mass% of the aqueous dispersion) is preferably 3 mass% or more and 30 mass% or less. When the concentration of the polyurethane precursor is 3 mass% or more, and more preferably 5 mass% or more, the polyurethane precursor can be uniformly added to the fibrous base material even in a case where the polyurethane precursor is added in a small amount. Meanwhile, when the concentration is 30 mass% or less, and more preferably 15 mass% or less, the storage stability of the aqueous dispersion can be enhanced.
When a dry heat coagulation method is used as the coagulation method, the coagulation temperature is preferably adjusted to be 55°C or more and 80°C or less. When the coagulation temperature is 55°C or more, and more preferably 60°C or more, gelation can be suppressed at the time of preparation or storage of the aqueous dispersion. Meanwhile, when the coagulation temperature is 80°C or less, and more preferably 70°C or less, coagulation of the polyurethane precursor proceeds before moisture evaporation from the fibrous base material, and thus a structure similar to a structure obtained by wet coagulation of a solvent-based polyurethane can be formed, that is, a structure in which a polyurethane does not strongly bind fibers constituting the nonwoven fabric or the woven fabric, so that good suppleness and resilience can be achieved.
In the method for manufacturing an artificial leather of the present invention, the aqueous dispersion may contain an inorganic salt in the case of using a dry heat coagulation method. When the aqueous dispersion contains an inorganic salt, thermosensitive coagulability can be imparted to the aqueous dispersion. In the present invention, the thermosensitive coagulability refers to a property of decreasing the fluidity of the aqueous dispersion and coagulating at a certain temperature (coagulation temperature) reached when the aqueous dispersion is heated.
In the present invention, in the case of using an inorganic salt as a thermosensitive coagulant, a monovalent cation-containing inorganic salt is preferably used. The monovalent cation-containing inorganic salt is preferably sodium chloride and/or sodium sulfate. The monovalent cation-containing inorganic salt, which has a small ionic valence, has a small influence on the stability of the aqueous dispersion, so that adjustment of the amount of the added monovalent cation-containing inorganic salt enables strict control of the thermosensitive coagulation temperature while the stability of the aqueous dispersion is ensured.
In the present invention, the content of the monovalent cation-containing inorganic salt in the aqueous dispersion is preferably 10 mass% or more and 50 mass% or less with respect to the polyurethane precursor. When the content is 10 mass% or more, more preferably 20 mass% or more, and still more preferably 30 mass% or more, ions present in a large amount in the aqueous dispersion uniformly act on the polyurethane precursor particles, so that coagulation can be quickly completed at a specific thermosensitive coagulation temperature. Thus, a more remarkable effect can be obtained on progress of coagulation of the polyurethane precursor in a state where the fibrous base material contains a large amount of moisture as described above. As a result, a structure can be formed that is very similar to that obtained by wet coagulation of a solvent-based polyurethane, and thus good suppleness and resilience can be achieved. Furthermore, when the amount of the added monovalent cation-containing inorganic salt is set as described above, the inorganic salt serves as an inhibitor of fusion of the polyurethane precursor particles, and can suppress hardening of the polyurethane precursor caused by continuous film formation. Meanwhile, when the content is 50 mass% or less, an appropriate continuous film structure of the polyurethane precursor can remain to suppress deterioration of physical properties. The stability of the aqueous dispersion can also be maintained.
In the method for manufacturing an artificial leather of the present invention, it is also preferable that the aqueous dispersion contains a crosslinking agent. When a three-dimensional network structure is introduced into the polyurethane precursor with a crosslinking agent, physical properties such as abrasion resistance can be improved.
The concentration of the crosslinking agent in the aqueous dispersion is preferably 1 mass% or more and 10 mass% or less with respect to the mass of the polyurethane precursor. When the concentration of the crosslinking agent in the aqueous dispersion is 1 mass% or more, and more preferably 2 mass% or more, a larger amount of three-dimensional network structure can be introduced into the polyurethane precursor with the crosslinking agent, and an artificial leather excellent in abrasion resistance and the like can be obtained. Meanwhile, when the concentration of the crosslinking agent is 10 mass% or less, and more preferably 7 mass% or less, it is suppressed that, at the time of forming the polyurethane precursor, the excessive crosslinking agent inhibits coagulation of the polyurethane precursor, and thus deterioration of physical properties such as abrasion resistance is easily suppressed.
In addition, the crosslinking agent preferably used in the method for manufacturing an artificial leather of the present invention is preferably a carbodiimide-based crosslinking agent and/or a blocked isocyanate crosslinking agent. Thus, a three-dimensional crosslinked structure can be added by a N-acylurea linkage and/or an isourea linkage, which is excellent in physical properties such as light resistance, heat resistance, and abrasion resistance and flexibility, into a molecule of the polymer elastic body in the artificial leather, and the physical properties such as durability and abrasion resistance can be dramatically improved while the suppleness of the artificial leather is maintained.
Then, after impregnating and coagulating the aqueous dispersion, a shrunk sheet having a width of 0.85L or more and 0.95L or less where the width of the fibrous base material before the impregnation of the sheet is denoted by L is obtained. As a method for shrinking the sheet in the width direction, a dry heat treatment at a temperature of 100°C or more and 180°C or less, a hot water treatment with hot water at 80°C or more and 100°C or less, or the like can be used. Examples of the dry heat treatment include a treatment of applying hot air from one side or both sides of the sheet using a floater dryer, a drum dryer, a pin tenter type dryer, or the like, and examples of the hot water treatment include a treatment of immersing the sheet in hot water at 80°C or more and 100°C or less, squeezing the sheet with a mangle, and then drying the sheet with a dryer.
From the viewpoint of production efficiency, the method for the coagulation of the aqueous dispersion and the method for the shrinking are preferably the same.
By shrinking the sheet in the width direction, the denseness of the surface of the artificial leather can be enhanced. In particular, by impregnating and coagulating the aqueous dispersion of the polyurethane, followed by the shrinking in the width direction, it is possible to prevent the polyurethane from firmly adhering to the woven fabric and to make the texture of the artificial leather suppler.
The degree of shrinkage in the width direction of the sheet can be prepared by the temperature of the heat treatment or the heat treatment time, and when the degree of shrinkage is set to 5% or more, and more preferably 10% or more relative to the width of the fibrous base material before impregnation, the above-mentioned effects can be made sufficient.
On the other hand, when the degree of shrinkage is set to 15% or less relative to the width of the fibrous base material before impregnation, quality abnormality such as wrinkling of the sheet can be prevented.
In the case of using a dry heat treatment as the shrinking treatment, when the temperature of the dry heat treatment is 100°C or more, preferably 120°C or more, and more preferably 130°C or more, the shrinking property of the sheet can be enhanced. On the other hand, by setting the temperature of the dry heat treatment to 180°C or less, and preferably 160°C or less, a decrease in durability of the artificial leather due to decomposition of polyurethane can be suppressed.
In the case of using a dry heat treatment as the shrinking treatment, the time of the dry heat treatment is preferably 5 minutes or more and 30 minutes or less. By heating for 5 minutes or more, and more preferably 10 minutes or more, the shrinking property of the sheet can be enhanced. By setting the time of the dry heat treatment to 30 minutes or less, and preferably 25 minutes or less, a decrease in durability of the artificial leather due to decomposition of polyurethane can be suppressed.

In this step, polyester ultrafine fibers are generated from ultrafine fiber-generating fibers of the shrunk sheet to form a sheet including, as constituents, a fibrous base material including polyester ultrafine fibers and a woven fabric, and the polyurethane having a hydrophilic group.
An ultrafine fiber-forming treatment (sea component dissolution treatment) in the case of using islands-in-the-sea composite fibers as the ultrafine fiber-generating fibers can be performed by a method in which, for example, the islands-in-the-sea composite fibers are immersed in a solvent and then a heat treatment is performed. The solvent for dissolving the sea component can be appropriately selected depending on the type of the sea component, and when the sea component is a copolymerized polyester, an aqueous solution of an alkali such as sodium hydroxide can be used, but it is preferable to perform the alkali treatment using an aqueous alkali solution which can be expected to have an effect of alleviating the adhesion between the woven fabric and the polyurethane.
In the case of using an aqueous alkali solution as the solvent for the sea component dissolution treatment, the molar concentration of the aqueous alkali solution is preferably 3 mol/L or less in order to prevent excessive deterioration of the polyurethane having a hydrophilic group.

In the method for manufacturing an artificial leather of the present invention as well, various finishing steps are preferably performed as in manufacture of common artificial leather.
First, the method for manufacturing an artificial leather of the present invention preferably includes a dyeing step of dyeing an artificial leather. As the dyeing treatment, it is possible to adopt various methods usually used in the art, and examples thereof include a jet dyeing treatment using a jigger dyeing machine or a jet dyeing machine, a dip dyeing treatment such as a thermosol dyeing treatment using a continuous dyeing machine, and a printing treatment to the napped surface, such as roller printing, screen printing, inkjet printing, sublimation printing, and vacuum sublimation printing. In particular, it is preferable to use a jet dyeing machine because it is possible to soften the non-napped artificial leather or the artificial leather by giving a kneading effect simultaneously with dyeing of the non-napped artificial leather or the artificial leather. Furthermore, various resin finishing may be performed after dyeing, as necessary.
In the dyeing bath or after dyeing, a finishing agent treatment can be performed using, for example, a softener such as silicone, an antistatic agent, a water repellent agent, a flame retardant, a light stabilizer, or an antimicrobial agent.
In the present invention, an aspect in which half-cut in the thickness direction is performed regardless of before or after the dyeing step is also preferable from the viewpoint of manufacturing efficiency.
The method for manufacturing an artificial leather of the present invention also preferably includes a napping step regardless of before or after the dyeing step. The method of napping is not particularly limited, and various methods commonly performed in the art, such as buffing with sandpaper or the like, can be used.
In a case where the napping treatment is performed, a lubricant such as a silicone emulsion may be applied to the surface of the artificial leather before the napping treatment. When an antistatic agent is further applied before the napping treatment, a buffing powder generated from the artificial leather by buffing is less likely to deposit on the sandpaper. Thus, an artificial leather is formed.
In the method for manufacturing an artificial leather of the present invention, the artificial leather may be further subjected to post-processing including drilling such as perforation, embossing, laser processing, pinsonic processing, and print processing, as necessary.

[Applications such as vehicle interior materials, vehicle components, and seats]

The artificial leather obtained according to the present invention is suitable as interior materials having a very elegant appearance, such as skin materials of furniture, chairs, walls, seats in vehicles including automobiles, trains, and aircrafts, ceiling, and interior decoration; clothing materials, such as shirts, jackets, upper and trim and the like of shoes including casual shoes, sports shoes, men's shoes and ladies' shoes, bags, belts, wallets, and a part of them; and industrial materials such as wiping cloth, abrasive cloth and CD curtains.
For example, an automobile interior material including the artificial leather is preferable because the characteristics of high strength and excellent suppleness and abrasion resistance can be utilized. Such an automobile interior material is preferably used for automobile components such as a steering wheel, a horn switch, a shift knob, a dashboard, an instrument panel, a glove box, a floor carpet, a floor mat, a ceiling lining, a sun visor, and an assist grip, and it is more preferable that at least a part of these automobile components is the artificial leather. The "automobile" referred to in the present invention is not limited to a so-called general passenger car, and includes some industrial machines, construction machines, and agricultural machines capable of carrying humans and animals, such as excavators, crane trucks, tractors, and combines.
In addition, a seat including the artificial leather is also preferable because the seat can utilize the characteristics of high strength and excellent suppleness and abrasion resistance. In such a seat, it is more preferable that at least a part, for example, a portion coming into direct contact with a sitter, of the skin material of a headrest, a seat surface, an armrest, a footrest, or the like is the above-described artificial leather. Of course, the seat of the present invention can be used as a seat not only for vehicles such as automobiles, aircraft, railway vehicles, and ships, but also for home use, office use, and store use. The "seat" referred to in the present invention includes a chair, a long chair, a sofa, a couch, a stool, a legless chair, and the like.

EXAMPLES

The artificial leather of the present invention will be described more specifically with reference to Examples, but the present invention is not limited to these Examples.

[Evaluation methods]

Evaluation methods used in Examples and the measurement conditions thereof will be described. Unless otherwise described, each physical property was measured on the basis of the above-described methods.

(1) Average single fiber diameter (µm):

The average single fiber diameter (µm) was measured and calculated by the above-described method using "VHX-D500/D510" manufactured by KEYENCE CORPORATION as a scanning electron microscope (SEM).

(2) Content rate (mass%) of polyurethane having hydrophilic group:

The content rate (mass%) of the polyurethane having a hydrophilic group was measured and calculated by the above-described method.

(3) Ratio (%) of filaments to which polyurethane is attached among outermost peripheral filaments of multifilament

The ratio (%) of filaments to which polyurethane was attached among outermost peripheral filaments of a multifilament was measured and calculated by the above-described method.

(4) Stiffness of artificial leather:

Based on the method A (45° cantilever method) in the text of 8.21.1 of 8.21 "Stiffness" of JIS L 1096:2010 "Testing methods for woven and knitted fabrics", five test pieces of 2 cm × 30 cm were prepared in the longitudinal direction of the sheet. Each test piece was placed on a horizontal table having a slope at an angle of 45 degrees, and was made to glide. Next, when a middle point at one end of the test piece was in contact with the slope, the scale was read. Then, the values for the five test pieces were averaged.

(5) Abrasion loss (mg) of artificial leather:

In the measurement and calculation of the abrasion loss (mg) of the artificial leather, "Model 406" manufactured by James H. Heal & Co. Ltd. was used as a Martindale abrasion tester, and "ABRASTIVE CLOTH SM25" manufactured by James H. Heal & Co. Ltd. was used as a standard friction cloth. Then, a load of 12 kPa was applied to the artificial leather, measurement was performed at the number of abrasions of 50,000 times, and the abrasion loss was calculated by the following formula using the masses of the artificial leather before and after the abrasions. Abrasion loss (mg) = mass before abrasion (mg) - mass after abrasion (mg)
A value obtained by rounding to the nearest whole number was regarded as the abrasion loss (mg).

(6) Abrasion loss (mg) of artificial leather after xenon irradiation

In the measurement and calculation of the abrasion loss (mg) of the artificial leather after xenon irradiation, the irradiation specified in "7.2 Exposure method a) First exposure method" of JIS L 0843: 2006 "Test methods for colour fastness to xenon arc lamp light" was performed, and then "Model 406" manufactured by James H. Heal & Co., Ltd. was used as a Martindale abrasion tester, and "ABRASTIVE CLOTH SM25" manufactured by James H. Heal & Co., Ltd. was used as a standard friction cloth. Then, a load of 12 kPa was applied to the artificial leather, measurement was performed at the number of abrasions of 10,000 times, and the abrasion loss was calculated by the following formula using the masses of the artificial leather before and after the abrasions. Abrasion loss (mg) = mass before abrasion (mg) - mass after abrasion (mg)
A value obtained by rounding to the nearest whole number was regarded as the abrasion loss (mg).

[Polyurethane precursor]

The polyurethane precursors used in Examples and Comparative Examples are as follows.
PU-A (a polyether-based polyurethane precursor containing a constituent component derived from a polyether-based polyol): a polyurethane precursor prepared from polytetramethylene glycol as a polymeric polyol, MDI as an organic diisocyanate, 2,2-dimethylolpropionic acid as an active hydrogen component-containing compound having a hydrophilic group, and ethylene glycol as a chain extender.
PU-B (a polycarbonate-based polyurethane precursor containing a constituent component derived from a polycarbonate-based polyol): a polyurethane precursor prepared from polyhexamethylene carbonate diol as a polymeric polyol, MDI as an organic diisocyanate, 2,2-dimethylolpropionic acid as an active hydrogen component-containing compound having a hydrophilic group, and ethylene glycol as a chain extender.

[Woven fabric]

The woven fabrics used in the examples and the comparative examples are as follows.
Woven fabric A: A plain woven fabric (weight per unit area: 75 g/m²) having a weave density of 95 warps/2.54 cm and 76 wefts/2.54 cm, obtained by using a twisted yarn prepared by twisting, at 2,500 T/m, a multifilament composed of 72 filaments having an average single fiber diameter of 11 µm made of polyethylene terephthalate having an intrinsic viscosity of 0.65 for both wefts and warps.
Woven fabric B: A plain woven fabric (weight per unit area: 75 g/m²) having a weave density of 95 warps/2.54 cm and 76 wefts/2.54 cm, obtained by using a twisted yarn prepared by twisting, at 2,500 T/m, a multifilament composed of 40 filaments having an average single fiber diameter of 15 µm made of polyethylene terephthalate having an intrinsic viscosity of 0.65 for both wefts and warps.
Woven fabric C: A plain woven fabric (weight per unit area: 75 g/m²) having a weave density of 190 warps/2.54 cm and 152 wefts/2.54 cm, obtained by using a twisted yarn prepared by twisting, at 2,500 T/m, a multifilament composed of 68 filaments having an average single fiber diameter of 8 µm made of polyethylene terephthalate having an intrinsic viscosity of 0.65 for both wefts and warps.

[Example 1]

A polyester obtained by copolymerizing 8 mol% of sodium 5-sulfoisophthalate was used as a sea component, polyethylene terephthalate having an intrinsic viscosity of 0.73 was used as an island component, and melt spinning was performed using an islands-in-the-sea composite spinneret having 16 islands per hole under the conditions of a spinning temperature of 285°C, an island/sea mass ratio of 80/20, a discharge rate of 1.6 g/min·hole, and a spinning speed of 1,100 m/min. Then, the spun yarn was drawn 3.7 times in an oil solution bath and cut into a length of 51 mm, affording a raw stock of islands-in-the-sea composite fibers having a single fiber fineness of 3.8 dtex. Then, the raw stock of islands-in-the-sea composite fibers was subjected to carding and cross-lapping steps to form a laminated web having an apparent density of 0.09 g/cm³, which was then layered with the woven fabric A and then subjected to needle punching at a punching density of 3,500 punches/cm², affording a fibrous base material composed of a nonwoven fabric made of the islands-in-the-sea composite fibers and the woven fabric and having a weight per unit area of 690 g/m², a thickness of 3.0 mm, a width of 170 cm, and an apparent density of 0.23 g/cm³.

As a polyurethane precursor, an aqueous dispersion composed of 12 parts by mass of PU-A as a polyether-based polyurethane precursor, 1 part by mass of a carbodiimide-based crosslinking agent ("CARBODILITE" (registered trademark) V-02-L2 manufactured by Nisshinbo Chemical Inc.), 5 parts by mass of sodium sulfate, and 82 parts by mass of water was prepared. A fibrous base material was impregnated with the aqueous dispersion, and the fibrous base material was then squeezed with a mangle such that the pick-up rate of the aqueous dispersion was 200 mass% based on the fibrous base material. The polyurethane precursor was coagulated by heating with hot air at 100°C for 10 minutes, and then the sheet was heated with hot air at 150°C for 10 minutes to shrink the sheet by 12% in the width direction relative to the width L of the fibrous base material before the impregnation. Thus, an impregnated sheet composed of a nonwoven fabric of islands-in-the-sea composite fibers, a woven fabric, and a polyurethane having a hydrophilic group, and having a width of 150 cm (0.88 L) was obtained.

The obtained impregnated sheet was immersed in a 5% aqueous sodium hydroxide solution, then squeezed with a mangle such that the pick-up rate of the aqueous sodium hydroxide solution was 100%, and then heated with steam at 95°C for 10 minutes to cause alkali-decomposition of the sea component of the islands-in-the-sea composite fibers. Then excess sodium hydroxide was washed with water, affording a sheet composed of polyester ultrafine fibers, a woven fabric, and a polyurethane having a hydrophilic group.

The obtained sheet was half-cut in a direction perpendicular to the thickness direction, and the half-cut surface was buffed with endless sandpaper with a sandpaper grit number of 180, affording a napped sheet having a thickness of 0.9 mm.
The resulting napped sheet was dyed using a disperse dye with a jet dyeing machine under a temperature condition of 120°C. The dyed napped sheet was dried with a dryer, affording an artificial leather containing ultrafine fibers having an average single fiber diameter of 4.4 µm, and also containing 23 mass% of a polyurethane having a hydrophilic group. Among the outermost peripheral filaments of the multifilament constituting the woven fabric of the obtained artificial leather fabric, the ratio (%) of the filaments to which the polyurethane was attached was 30%, and the artificial leather had a supple texture and excellent durability. The results are shown in Table 1.

[Example 2]

An artificial leather containing ultrafine fibers having an average single fiber diameter of 4.4 µm, and also containing 23 mass% of a polyurethane having a hydrophilic group was obtained in the same manner as in Example 1 except that the woven fabric was changed to the woven fabric B in <Step of forming fibrous base material>. The width of the impregnated sheet obtained by <Step of forming impregnated sheet and shrinking impregnated sheet in width direction> was shrunk by 12% in the width direction based on the width L of the fibrous base material before impregnation, and was 150 cm (0.88L).
Among the outermost peripheral filaments of the multifilament constituting the woven fabric of the obtained artificial leather fabric, the ratio (%) of the filaments to which the polyurethane was attached was 45%, and the artificial leather was slightly inferior in suppleness to Example 1, but had a supple texture and excellent durability. The results are shown in Table 1.

[Example 3]

An artificial leather containing ultrafine fibers having an average single fiber diameter of 4.4 µm, and also containing 23 mass% of a polyurethane having a hydrophilic group was obtained in the same manner as in Example 1 except that the woven fabric was changed to the woven fabric C in <Step of forming fibrous base material>. The width of the impregnated sheet obtained by <Step of forming impregnated sheet and shrinking impregnated sheet in width direction> was shrunk by 12% in the width direction based on the width L of the fibrous base material before impregnation, and was 150 cm (0.88L).
Among the outermost peripheral filaments of the multifilament constituting the woven fabric of the obtained artificial leather fabric, the ratio (%) of the filaments to which the polyurethane was attached was 65%, and the artificial leather was slightly inferior in suppleness to Example 1, but had a supple texture and excellent durability. The results are shown in Table 1.

[Example 4]

An artificial leather containing ultrafine fibers having an average single fiber diameter of 4.4 µm, and also containing 23 mass% of a polyurethane having a hydrophilic group was obtained in the same manner as in Example 1 except that the heating conditions after coagulating the polyurethane precursor were changed to using hot air at 120°C for 10 minutes in <Step of forming impregnated sheet and shrinking impregnated sheet in width direction>. The width of the impregnated sheet obtained by <Step of forming impregnated sheet and shrinking impregnated sheet in width direction> was shrunk by 6% in the width direction based on the width L of the fibrous base material before impregnation, and was 160 cm (0.94L).
Among the outermost peripheral filaments of the multifilament constituting the woven fabric of the obtained artificial leather fabric, the ratio (%) of the filaments to which the polyurethane was attached was 39%, and the artificial leather was slightly inferior in suppleness to Example 1, but had a supple texture and excellent durability. The results are shown in Table 1.

[Example 5]

An artificial leather containing ultrafine fibers having an average single fiber diameter of 4.4 µm, and also containing 23 mass% of a polyurethane having a hydrophilic group was obtained in the same manner as in Example 1 except that the polyurethane precursor was changed to PU-B, which was a polycarbonate-based polyurethane precursor, in <Step of forming impregnated sheet and shrinking impregnated sheet in width direction>. The width of the impregnated sheet obtained by <Step of forming impregnated sheet and shrinking impregnated sheet in width direction> was shrunk by 12% in the width direction based on the width L of the fibrous base material before impregnation, and was 150 cm (0.88L).
Among the outermost peripheral filaments of the multifilament constituting the woven fabric of the obtained artificial leather fabric, the ratio (%) of the filaments to which the polyurethane was attached was 32%, and the artificial leather was slightly inferior in suppleness to Example 1, but had a supple texture and extremely excellent durability. The results are shown in Table 1.

[Example 6]

An artificial leather containing ultrafine fibers having an average single fiber diameter of 4.4 µm, and also containing 18 mass% of a polyurethane having a hydrophilic group was obtained in the same manner as in Example 1 except that the pick-up ratio of the aqueous dispersion was changed to 140 mass% based on the fibrous base material in <Step of forming impregnated sheet and shrinking impregnated sheet in width direction>. The width of the impregnated sheet obtained by <Step of forming impregnated sheet and shrinking impregnated sheet in width direction> was shrunk by 12% in the width direction based on the width L of the fibrous base material before impregnation, and was 150 cm (0.88L).
Among the outermost peripheral filaments of the multifilament constituting the woven fabric of the obtained artificial leather fabric, the ratio (%) of the filaments to which the polyurethane was attached was 22%, and the artificial leather had a supple texture and excellent durability. The results are shown in Table 1.

[Example 7]

An artificial leather containing ultrafine fibers having an average single fiber diameter of 4.4 µm, and also containing 23 mass% of a polyurethane having a hydrophilic group was obtained in the same manner as in Example 1 except that the heating conditions of the coagulation of the polyurethane precursor and after the coagulation were changed to steam at 98°C in <Step of forming impregnated sheet and shrinking impregnated sheet in width direction>. The width of the impregnated sheet obtained by <Step of forming impregnated sheet and shrinking impregnated sheet in width direction> was shrunk by 5% in the width direction based on the width L of the fibrous base material before impregnation, and was 162 cm (0.95L).
Among the outermost peripheral filaments of the multifilament constituting the woven fabric of the obtained artificial leather fabric, the ratio (%) of the filaments to which the polyurethane was attached was 47%, and the artificial leather was slightly inferior in suppleness to Example 1, but had a supple texture and excellent durability. The results are shown in Table 1.

[Example 8]

An artificial leather containing ultrafine fibers having an average single fiber diameter of 4.4 µm, and also containing 23 mass% of a polyurethane having a hydrophilic group was obtained in the same manner as in Example 1 except that the concentration of sodium hydroxide was changed to 3% and the pick-up rate was changed to 200% in <Step of generating polyester ultrafine fibers>. The width of the impregnated sheet obtained by <Step of forming impregnated sheet and shrinking impregnated sheet in width direction> was shrunk by 12% in the width direction based on the width L of the fibrous base material before impregnation, and was 150 cm (0.88L).
Among the outermost peripheral filaments of the multifilament constituting the woven fabric of the obtained artificial leather fabric, the ratio (%) of the filaments to which the polyurethane was attached was 40%, and the artificial leather was slightly inferior in suppleness to Example 1, but had a supple texture and extremely excellent durability. The results are shown in Table 1.

[Comparative Example 1]

An artificial leather containing ultrafine fibers having an average single fiber diameter of 4.4 µm, and also containing 23 mass% of a polyurethane having a hydrophilic group was obtained in the same manner as in Example 1 except that the fibrous base material was shrunk to 150 cm in the width direction with hot water at 97°C before impregnation with the aqueous dispersion and the shrinking in the width direction after the coagulation of the polyurethane precursor was not conducted in <Step of forming impregnated sheet and shrinking impregnated sheet in width direction>. The width of the impregnated sheet obtained by <Step of forming impregnated sheet and shrinking impregnated sheet in width direction> was not shrunk in the width direction based on the width L of the fibrous base material before impregnation, and was kept at 150 cm (1.00L).
Among the outermost peripheral filaments of the multifilament constituting the filaments of the obtained artificial leather, the ratio (%) of the fibers to which the polyurethane was attached was 95%, and the obtained artificial leather had excellent durability, but the texture thereof was hard. The results are shown in Table 1.

[Comparative Example 2]

An artificial leather containing ultrafine fibers having an average single fiber diameter of 4.4 µm, and also containing 13 mass% of a polyurethane having a hydrophilic group was obtained in the same manner as in Example 1 except that the pick-up ratio of the aqueous dispersion was changed to 100 mass% based on the fibrous base material in <Step of forming impregnated sheet and shrinking impregnated sheet in width direction>. The width of the impregnated sheet obtained by <Step of forming impregnated sheet and shrinking impregnated sheet in width direction> was shrunk by 12% in the width direction based on the width L of the fibrous base material before impregnation, and was 150 cm (0.88L).
Among the outermost peripheral filaments of the multifilament constituting the woven fabric of the obtained artificial leather, the ratio (%) of the filaments to which the polyurethane was attached was 8%, and the obtained artificial leather had an excellent texture, but was significantly poor in durability. The results are shown in Table 1.

[Comparative Example 3]

An artificial leather containing ultrafine fibers having an average single fiber diameter of 4.4 µm, and also containing 29 mass% of a polyurethane having a hydrophilic group was obtained in the same manner as in Example 1 except that the pick-up ratio of the aqueous dispersion was changed to 250 mass% based on the fibrous base material in <Step of forming impregnated sheet and shrinking impregnated sheet in width direction>. The width of the impregnated sheet obtained by <Step of forming impregnated sheet and shrinking impregnated sheet in width direction> was shrunk by 12% in the width direction based on the width L of the fibrous base material before impregnation, and was 150 cm (0.88L).
Among the outermost peripheral filaments of the multifilament constituting the woven fabric of the obtained artificial leather fabric, the ratio (%) of the filaments to which the polyurethane was attached was 82%, and the obtained artificial leather had excellent durability, but the texture thereof was hard. The results are shown in Table 1.

[Comparative Example 4]

An artificial leather containing ultrafine fibers having an average single fiber diameter of 4.4 µm, and also containing 23 mass% of a polyurethane having a hydrophilic group was obtained by shrinking the fibrous base material to 150 cm in the width direction with hot water at 97°C before impregnation with the aqueous dispersion and, at the same time, adding a polyvinyl alcohol having a degree of saponification of 98% in an amount of 10 mass% based on the mass of the fibrous base material in <Step of forming impregnated sheet and shrinking impregnated sheet in width direction>. The width of the impregnated sheet obtained by <Step of forming impregnated sheet and shrinking impregnated sheet in width direction> was not shrunk in the width direction based on the width L of the fibrous base material before impregnation, and was kept at 150 cm (1.00L).
Among the outermost peripheral filaments of the multifilament constituting the filaments of the obtained artificial leather, the ratio (%) of the fibers to which the polyurethane was attached was 95%, and the obtained artificial leather had excellent durability, but the texture thereof was hard. The results are shown in Table 1.

A fibrous base material composed of a nonwoven fabric made of islands-in-the-sea composite fibers and a woven fabric was obtained in the same manner as in Example 1.

A fibrous base material with polyvinyl alcohol was obtained by shrinking the fibrous base material to 150 cm in the width direction with hot water at 97°C before impregnation with the aqueous dispersion and, at the same time, adding a polyvinyl alcohol having a degree of saponification of 98% in an amount of 10 mass% based on the mass of the fibrous base material, and drying the fibrous base material with hot air at 100°C. Next, as a polyurethane precursor, an aqueous dispersion composed of 12 parts by mass of PU-A as a polyether-based polyurethane precursor, 1 part by mass of a carbodiimide-based crosslinking agent ("CARBODILITE" (registered trademark) V-02-L2 manufactured by Nisshinbo Chemical Inc.), 5 parts by mass of sodium sulfate, and 82 parts by mass of water was prepared. A fibrous base material was impregnated with the aqueous dispersion, and the fibrous base material was then squeezed with a mangle such that the pick-up rate of the aqueous dispersion was 200 mass% based on the fibrous base material. The polyurethane precursor was coagulated by heating with hot air at 100°C for 10 minutes, and then the sheet was heated with hot air at 150°C for 10 minutes, affording an impregnated sheet composed of a nonwoven fabric of islands-in-the-sea fibers, a woven fabric, a polyurethane having a hydrophilic group, and polyvinyl alcohol.

The obtained impregnated sheet was subjected to an alkali treatment in the same manner as in Example 1, whereby polyester ultrafine fibers were generated. In addition, polyvinyl alcohol was removed with hot water at 100°C, whereby a sheet composed of polyester ultrafine fibers, a woven fabric, and a polyurethane having a hydrophilic group was obtained.

The obtained sheet was subjected to finishing in the same manner as in Example 1, affording an artificial leather containing ultrafine fibers having an average single fiber diameter of 4.4 µm, and also containing 23 mass% of a polyurethane having a hydrophilic group. Among the outermost peripheral filaments of the multifilament constituting the woven fabric of the obtained artificial leather fabric, the ratio (%) of the filaments to which the polyurethane was attached was 3%, and the artificial leather had a supple texture and extremely excellent durability, but polyvinyl alcohol was used, and the process load was higher than that in Example 1. The results are shown in Table 1.

[Table 1-1]

	Example 1	Example 2	Example 3	Example 4	Example 5	Example 6
Average single fiber diameter [µm] of polyester ultrafine fibers	4.4	4.4	4.4	4.4	4.4	4.4
Type of woven fabric	Woven fabric A	Woven fabric B	Woven fabric C	Woven fabric A	Woven fabric A	Woven fabric A
Average single fiber diameter [µm] of fibers constituting woven fabric	11	15	8	11	11	11
Number of filaments of fibers constituting woven fabric	72	40	68	72	72	72
Type of polyurethane precursor	PU-A	PU-A	PU-A	PU-A	PU-B	PU-A
Content rate [mass%] of polyurethane having hydrophilic group	23	23	23	23	23	18
Shrinkage rate [%] in width direction based on width of fibrous base material before impregnation of sheet obtained by coagulating polyurethane	12	12	12	6	12	12
Width [-] based on width L of fibrous base material before impregnation of sheet obtained by coagulating polyurethane	0.88 L	0.88 L	0.88 L	0.94 L	0.88 L	0.88 L
Ratio [%] of filaments to which polyurethane is attached among outermost peripheral filaments of multifilament	30	45	65	39	32	22
Stiffness [mm] of artificial leather	62	101	148	94	140	54
Abrasion loss [mg] of artificial leather	22	23	21	22	16	34
Abrasion loss [mg] of artificial leather after xenon irradiation	6	6	6	7	4	11

[Table 1-2]

	Example 7	Example 8	Comparative Example 1	Comparative Example 2	Comparative Example 3	Comparative Example 4
Average single fiber diameter [µm] of polyester ultrafine fibers	4.4	4.4	4.4	4.4	4.4	4.4
Type of woven fabric	Woven fabric A	Woven fabric A	Woven fabric A	Woven fabric A	Woven fabric A	Woven fabric A
Average single fiber diameter [um] of fibers constituting woven fabric	11	11	11	11	11	11
Number of filaments of fibers constituting woven fabric	72	72	72	72	72	72
Type of polyurethane precursor	PU-A	PU-A	PU-A	PU-A	PU-A	PU-A
Content rate [mass%] of polyurethane having hydrophilic group	23	23	23	13	29	23
Shrinkage rate [%] in width direction based on width of fibrous base material before impregnation of sheet obtained by coagulating polyurethane	5	12	0	10	9	0
Width [-] based on width L of fibrous base material before impregnation of sheet obtained by coagulating polyurethane	0.95 L	0.88 L	1.00 L	0.88 L	0.88 L	1.00 L
Ratio [%] of filaments to which polyurethane is attached among outermost peripheral filaments of multifilament	47	40	95	8	82	3
Stiffness [mm] of artificial leather	114	95	> 200	78	180	46
Abrasion loss [mg] of artificial leather	24	20	20	46	20	23
Abrasion loss [mg] of artificial leather after xenon irradiation	7	6	6	14	6	6

INDUSTRIAL APPLICABILITY

The artificial leather obtained according to the present invention is suitable as interior materials having a very elegant appearance, such as skin materials of furniture, chairs, walls, seats in vehicles including automobiles, trains, and aircrafts, ceiling, and interior decoration; clothing materials, such as shirts, jackets, upper and trim and the like of shoes including casual shoes, sports shoes, men's shoes and ladies' shoes, bags, belts, wallets, and a part of them; and industrial materials such as wiping cloth, abrasive cloth and CD curtains.

DESCRIPTION OF REFERENCE SIGNS

1:: Multifilament constituting woven fabric
2:: Polyurethane
3:: Filament to which polyurethane is attached
4:: Filament to which no polyurethane is attached

Claims

An artificial leather comprising: a fibrous base material composed of a nonwoven fabric and a woven fabric entangled and integrated together; and a polyurethane having a hydrophilic group, wherein
the nonwoven fabric is composed of polyester ultrafine fibers having an average single fiber diameter of 0.1 µm or more and 10.0 µm or less,

the woven fabric is composed of a multifilament having 30 or more and 300 or less filaments, and the filaments constituting the multifilament have an average single fiber diameter of 1 µm or more and 30 µm or less,

a content rate of the polyurethane in the artificial leather is 15 mass% or more and 25 mass% or less, and

a ratio of filaments to which the polyurethane is attached among outermost peripheral filaments of the multifilament is 10% or more and 80% or less.
The artificial leather according to claim 1, wherein the polyurethane is a polyether-based polyurethane and/or a polycarbonate-based polyurethane.
A method for manufacturing the artificial leather according to claim 1, comprising the following steps (1) to (3) arranged in this order:
(1) a step of entangling and integrating a nonwoven fabric composed of ultrafine fiber-generating fibers and a woven fabric together to form a fibrous base material,

(2) a step of impregnating the fibrous base material with an aqueous dispersion of a polyurethane having a hydrophilic group, then coagulating the polyurethane to obtain a sheet, and obtaining a shrunk sheet having a width of 0.85L or more and 0.95L or less where a width of the fibrous base material before the impregnation is denoted by L for that obtained sheet,

(3) a step of generating polyester ultrafine fibers from the ultrafine fiber-generating fibers of the shrunk sheet.
The method for manufacturing the artificial leather according to claim 3, wherein means of entanglement and integration in the step (1) is needle punching.
The method for manufacturing the artificial leather according to claim 3 or 4, wherein a means for obtaining the shrunk sheet in the step (2) is dry heat treatment at an atmospheric temperature of 100°C or more and 180°C or less.
The method for manufacturing the artificial leather according to claim 3 or 4, wherein a means for generating the polyester ultrafine fibers in the step (3) is an alkali treatment.
An automobile interior material comprising the artificial leather according to claim 1 or 2.
An automobile component comprising the artificial leather according to claim 1 or 2.
A seat comprising the artificial leather according to claim 1 or 2.