Artificial leather and manufacturing method thereof, clothing, bag

Abstract

To obtain an artificial leather that is excellent in air permeability and has elegant appearance on both sides.SOLUTION: An artificial leather includes a fibrous base material and elastomer. The fibrous base material has a nonwoven fabric constituted of ultra fine fibers with 1.0 μm or more and 10.0 μm or less of average single fiber diameter, and a woven fabric. When a surface on far side from the woven fabric of the artificial leather is a first surface, and a surface on the opposite side of the first surface is a second surface, the first surface and the second surface satisfy following requirements 1 to 3. Requirement 1: the first surface and the second surface have nap. Requirement 2: the first surface has 200 μm or more and 500 μm or less of average napping length and 30% or less of napping length variation coefficient. Requirement 3: the second surface has 97.5% or more of napping coverage, 500 μm or more and 1000 μm or less of average napping length, and 30% or less of napping length variation coefficient.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to artificial leather. [Background technology]

[0002] Artificial leather, which is made primarily of a fibrous substrate such as a nonwoven fabric made of ultrafine fibers and a polymeric elastomer, has excellent characteristics not found in natural leather, such as high durability and uniformity. Among these, so-called suede-like artificial leather, which has its surface buffed to form a raised nap of ultrafine fibers, is used not only as a clothing material but also in a variety of fields, including vehicle interior materials, furniture and interior materials, and building materials. To produce suede-like artificial leather that is particularly strong and can withstand long-term use, a method has been proposed in which a woven or knitted fabric is entangled and integrated with one side of the nonwoven fabric.

[0003] For example, Patent Document 1 proposes an artificial leather having nap on both surfaces, with the nap length on the surface closer to the fabric being 50 μm to 150 μm, and with a resin layer formed on the surface farther from the fabric. It is described that this artificial leather has low fiber shedding due to friction or rubbing.

[0004] Patent Document 2 proposes a method for promoting the entanglement of ultrafine fiber bundles by performing a liquid flow treatment in or after the step of developing ultrafine fibers. It is described that this method makes it possible to obtain artificial leather with a more elegant appearance. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Publication No. 2022-44227 [Patent Document 2] Japanese Patent Application Laid-Open No. 2017-133134 Summary of the Invention [Problem to be solved by the invention]

[0006] In Patent Document 1, although the artificial leather has raised nap on both sides, a resin layer is formed on the surface away from the woven fabric to prevent fiber shedding, which limits its uses and leaves room for improvement in design freedom.

[0007] Furthermore, in Patent Document 2, the artificial leather is strongly pressed in the thickness direction by the liquid flow treatment, which tends to result in a high density artificial leather, and there is room for improvement in breathability.

[0008] The present invention has been made in view of the above problems, and aims to provide artificial leather that is excellent in breathability and has an elegant appearance on both sides, and that is made of a fibrous substrate in which a nonwoven fabric composed of ultrafine fibers and a woven fabric are entangled and integrated, and a polymeric elastomer. [Means for solving the problem]

[0009] The present inventors conducted extensive research to solve the above-mentioned problems and found that the nap coverage and nap length on the surface closest to the woven fabric are important factors in obtaining artificial leather with a beautiful appearance on both sides. They also found that by adding solids derived from silicone and non-silicone textile oils to ultrafine fiber-producing fibers and increasing the number of fibers of the nonwoven fabric penetrating the woven fabric when the nonwoven fabric and the woven fabric are entangled and integrated by needle punching, artificial leather with a beautiful appearance on both sides and excellent breathability can be obtained. Further research led to the discovery that by heat-treating an ultrafine fiber sheet to which a polymeric elastomer has been added for a predetermined time in an atmosphere within a predetermined temperature range, artificial leather with a beautiful appearance on both sides, excellent breathability, and excellent abrasion resistance can be obtained.

[0010] The present invention has been completed based on these findings, and provides the following inventions.

[0011] [1] An artificial leather comprising a fibrous base material and a polymeric elastomer, The fibrous base material comprises a nonwoven fabric made of ultrafine fibers having an average single fiber diameter of 1.0 μm or more and 10.0 μm or less, and a woven fabric, and when the surface of the artificial leather farther from the woven fabric is defined as a first surface and the surface opposite to the first surface is defined as a second surface, the first surface and the second surface satisfy the following requirements 1 to 3. Requirement 1: Both the first surface and the second surface have nap. Requirement 2: On the first surface, the average value of the nap length is 200 μm or more and 500 μm or less, and the coefficient of variation of the nap length is 30% or less. Requirement 3: On the second surface, the nap coverage is 97.5% or more, the average nap length is 500 μm or more and 1000 μm or less, and the coefficient of variation of the nap length is 30% or less.

[0012] [2] The artificial leather according to [1], wherein the polymeric elastomer is a polyurethane having a hydrophilic group, and the polyurethane is a polyether-based polyurethane and / or a polycarbonate-based polyurethane.

[0013] [3] The artificial leather according to [1] or [2], wherein the content of the polymeric elastomer in the artificial leather is 15% by mass or more and 25% by mass or less.

[0014] [4] The artificial leather according to any one of [1] to [3], wherein the woven fabric has a fiber weave density of 70 threads / 2.54 cm or more and 120 threads / 2.54 cm or less.

[0015] [5] The apparent density of the artificial leather is 0.20 g / cm 3 More than 0.40g / cm 3 The artificial leather according to any one of the above [1] to [4], which is as follows:

[0016] [6] Clothing comprising the artificial leather according to any one of [1] to [5] above.

[0017] [7] A bag comprising the artificial leather according to any one of [1] to [5] above.

[0018] [8] A process for obtaining a nonwoven fabric composed of ultrafine fiber-developing fibers, in which the sea component is an islands-in-sea type composite fiber that is an alkali-soluble resin, and to which solids derived from a mixed oil solution of silicone and non-silicone fiber oil solution are attached, and the amount of the attached solids is 0.30 mass % or more and 1.00 mass % or less; a step of entangling and integrating the nonwoven fabric and the woven fabric to obtain a fibrous substrate; a step of providing a polymeric elastomer to the fibrous base material to obtain a polymeric elastomer-coated sheet; a step of treating the polymeric elastomer-attached sheet with an alkali to produce ultrafine fibers having an average single fiber diameter of 1.0 μm or more and 10.0 μm or less from the ultrafine fiber-producing fibers, thereby obtaining an ultrafine fiber sheet; a step of heat-treating the ultrafine fiber sheet at an atmospheric temperature of 150°C or higher and 200°C or lower for 5 minutes or longer and 20 minutes or shorter to obtain a heat-treated sheet; grinding the surface of the heat treatment sheet away from the fabric to form a first surface having nap; grinding or scraping the other surface to form a second surface having nap; A method for producing artificial leather, comprising: On the first surface, the average value of the nap length is 200 μm or more and 500 μm or less, and the coefficient of variation of the nap length is 30% or less, On the second surface, the nap coverage is 97.5% or more, the average value of the nap length is 500 μm or more and 1000 μm or less, and the coefficient of variation of the nap length is 30% or less. A method for manufacturing artificial leather.

[0019] [9] The method for producing an artificial leather according to [8], wherein the proportion of silicone in the solid content derived from the mixed oil agent is 30% by mass or more and 70% by mass or less.

[0020]

[10] A method for producing an artificial leather according to [8] or [9], wherein the alkali-soluble resin is a copolymer polyester copolymerized with a polyalkylene glycol having a number average molecular weight of 500 or more and 3500 or less.

[0021]

[11] The method for producing an artificial leather according to any one of [8] to

[10] above, wherein in the step of obtaining the fibrous base material, the fibers are entangled and integrated by needle punching. [Effects of the Invention]

[0022] According to the present invention, it is possible to obtain an artificial leather which is excellent in breathability and has an elegant appearance on both sides, and which is made of a fibrous substrate in which a nonwoven fabric made of ultrafine fibers and a woven fabric are entangled and integrated, and a polymeric elastomer. Furthermore, the artificial leather of the present invention has an elegant appearance similar to natural leather on both sides, and can be used in a wide range of applications, from furniture, chairs, and vehicle interior materials to clothing, but is particularly suitable for use in clothing and bags. [Brief explanation of the drawings]

[0023] [Figure 1] FIG. 1 is a cross-sectional conceptual diagram illustrating the first and second surfaces of the artificial leather of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0024] The artificial leather of the present invention is an artificial leather comprising a fibrous base material and a polymeric elastomer, wherein the fibrous base material comprises a nonwoven fabric composed of ultrafine fibers having an average single fiber diameter of 1.0 μm or more and 10.0 μm or less, and a woven fabric, and wherein when the surface of the artificial leather farther from the woven fabric is defined as a first surface and the surface opposite to the first surface is defined as a second surface, the first surface and the second surface satisfy the following requirements 1 to 3. Requirement 1: Both the first surface and the second surface have nap. Requirement 2: On the first surface, the average value of the nap length is 200 μm or more and 500 μm or less, and the coefficient of variation of the nap length is 30% or less. Requirement 3: On the second surface, the nap coverage is 97.5% or more, the average nap length is 500 μm or more and 1000 μm or less, and the coefficient of variation of the nap length is 30% or less.

[0025] These components will be described in detail below, but the present invention is not limited to the scope described below as long as it does not go beyond the gist of the present invention, and various modifications are possible within the scope of the present invention.

[0026] [Nonwoven fabric made of ultrafine fibers] The artificial leather of the present invention is composed of a fibrous substrate, one of the components, which is made up of a nonwoven fabric and a woven fabric, each composed of ultrafine fibers having an average single fiber diameter of 1.0 μm to 10.0 μm. As the component constituting the ultrafine fibers, polyester resins and polyamide resins are preferably used from the viewpoint of durability, particularly mechanical strength, and polyester resins, which have excellent heat resistance, are more preferably used. Note that ultrafine fibers refer to fibers having a single fiber diameter of 20.0 μm or less, as measured and calculated by the method described below.

[0027] In this invention, "polyester-based resin" refers to a resin in which the molar fraction of the polyester unit in the repeating units is 80 mol % or more and 100 mol % or less. Unless otherwise specified, the same applies to "...-based resin."

[0028] The polyester resin can be obtained from, for example, a dicarboxylic acid and / or its ester-forming derivative and a diol.

[0029] Examples of dicarboxylic acids and / or ester-forming derivatives thereof used in the polyester resin include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4'-dicarboxylic acid, and ester-forming derivatives thereof. The ester-forming derivatives referred to in the present invention include lower alkyl esters, acid anhydrides, and acyl chlorides of dicarboxylic acids. Specifically, methyl esters, ethyl esters, and hydroxyethyl esters are preferably used. A more preferred embodiment of the dicarboxylic acid and / or ester-forming derivatives thereof used in the present invention is terephthalic acid and / or its dimethyl ester.

[0030] Examples of diols used in the polyester resin include ethylene glycol, 1,3-propanediol, 1,4-butanediol, cyclohexanedimethanol, etc. Among these, ethylene glycol is preferably used.

[0031] Among these, polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and mixtures and copolymers of these polyester resins are preferred, as they can be used to produce artificial leather with excellent heat resistance, light resistance, etc.

[0032] The polyester resin may contain inorganic particles such as titanium oxide particles, lubricants, pigments, heat stabilizers, ultraviolet absorbers, conductive agents, heat storage agents, antibacterial agents, etc., depending on various purposes.

[0033] The cross-sectional shape of the ultrafine fibers may be either round or irregular. Specific examples of irregular cross sections include oval, flat, polygonal such as triangular (including those with rounded corners), sector, and cross.

[0034] In the present invention, the average single fiber diameter of the ultrafine fibers is 1.0 μm or more and 10.0 μm or less. By making the average single fiber diameter of the ultrafine fibers 10.0 μm or less, preferably 7.0 μm or less, and more preferably 5.0 μm or less, the artificial leather becomes more flexible. In addition, the quality of the nap can be improved. On the other hand, by making the average single fiber diameter of the ultrafine fibers 1.0 μm or more, preferably 1.5 μm or more, and more preferably 2.0 μm or more, the artificial leather becomes excellent in color development after dyeing. In addition, when performing a nap raising treatment by buffing, the ease of dispersion and handling of the ultrafine fibers present in bundles can be improved.

[0035] The single fiber diameter and average single fiber diameter of the ultrafine fibers in the present invention are measured and calculated by the following method. (1) The cross section of the obtained artificial leather cut in the thickness direction is observed using a scanning electron microscope (SEM, Keyence Corporation's "VHX-D500 / D510" or a scanning electron microscope with equivalent performance). (2) The single fiber diameter of 50 randomly selected ultrafine fibers within the observation area is measured at the cross section of each ultrafine fiber, and this operation is carried out three times in total at different locations. However, when ultrafine fibers with irregular cross sections are used, the cross-sectional area of ​​the ultrafine fibers is first measured, and the diameter of the circle corresponding to that cross-sectional area is calculated using the following formula. The diameter obtained is the single fiber diameter of the single fiber. Single fiber diameter (μm) = (4 × (cross-sectional area of ​​single fiber (μm 2 )) / π) 1 / 2 ···(formula) (3) The arithmetic mean value (μm) of the 150 points obtained is calculated and rounded off to the second decimal place to obtain the average single fiber diameter (μm) of the ultrafine fibers.

[0036] The nonwoven fabric may be either a long fiber nonwoven fabric or a short fiber nonwoven fabric, but a short fiber nonwoven fabric is preferred because it has a large number of naps on the product surface and tends to give an elegant appearance.

[0037] In the case of a short-fiber nonwoven fabric, the fiber length of the ultrafine fibers is preferably 25 mm or more and 90 mm or less. By setting the fiber length of the ultrafine fibers to 25 mm or more, preferably 35 mm or more, and more preferably 40 mm or more, the artificial leather will have an elegant appearance. On the other hand, by setting the fiber length of the ultrafine fibers to 90 mm or less, preferably 80 mm or less, and more preferably 70 mm or less, the artificial leather will have good surface quality and texture.

[0038] [fabric] Multifilaments are preferably used as the fibers constituting the woven fabric of the artificial leather of the present invention. While polyester resins and polyamide resins can be used as components constituting the filaments of multifilaments, polyester resins, which have excellent durability and heat resistance, are preferably used. Specific examples of polyester resins include polyalkylene terephthalates such as polyethylene terephthalate, polybutylene terephthalate, and polytrimethylene terephthalate, as well as mixtures and copolymers of these polyester resins.

[0039] The average single fiber diameter of the multifilament filaments constituting the woven fabric is preferably 1.0 μm or more and 30.0 μm or less. By setting the average single fiber diameter to 30.0 μm or less, preferably 15.0 μm or less, and more preferably 13.0 μm or less, an artificial leather with excellent flexibility is obtained. On the other hand, by setting the average single fiber diameter to 1.0 μm or more, preferably 8.0 μm or more, and more preferably 9.0 μm or more, damage to the filaments during processing can be prevented, and when a product shape is imparted, the shape can be easily maintained, that is, an artificial leather with excellent shape retention can be obtained.

[0040] In the present invention, the average single fiber diameter of the filaments of the multifilament composing the woven fabric is measured and calculated by the following method. (1) The cross section of the obtained artificial leather cut in the thickness direction is observed using a scanning electron microscope (SEM, Keyence Corporation's "VHX-D500 / D510" or a scanning electron microscope with equivalent performance). (2) The single fiber diameter of any 10 filaments within the observation area is measured at each filament cross section, and this operation is performed a total of three times at different locations. However, if a filament with a modified cross section is used, the cross-sectional area of ​​the single fiber is first measured, and the diameter of the circle with that cross-sectional area is calculated using the following formula. The diameter obtained is the single fiber diameter of that single fiber. Single fiber diameter (μm) = (4 × (cross-sectional area of ​​single fiber (μm 2 )) / π) 1 / 2 ···(formula) (3) Calculate the arithmetic mean value (μm) of the 30 points obtained, round off to the second decimal place, and use this as the average single fiber diameter (μm) of the filament.

[0041] The number of filaments contained in the multifilament constituting the woven fabric, i.e., the number of filaments, is preferably 30 to 300. Having 30 or more, preferably 50 or more, filaments results in an artificial leather with excellent shape retention, and is also preferred because the fibers constituting 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 by needle punching or the like. On the other hand, having 300 or less, preferably 250 or less, more preferably 100 or less, filaments results in an artificial leather with excellent flexibility. In this case, the number of filaments in the warp and the number of filaments in the weft may be the same or different.

[0042] Furthermore, the twist number of the multifilament is preferably 1000 T / m or more and 4000 T / m or less. By setting the twist number to 4000 T / m or less, preferably 3500 T / m or less, and more preferably 3000 T / m or less, an artificial leather with excellent flexibility is obtained, while by setting the twist number to 1000 T / m or more, preferably 1500 T / m or more, and more preferably 2000 T / m or more, damage to the fibers constituting the woven fabric can be prevented when the nonwoven fabric and the woven fabric are entangled and integrated by needle punching or the like, and an artificial leather with excellent mechanical strength is obtained, which is preferable.

[0043] The basic weave of the fabric may be twill or satin, but plain weave, which is less likely to cause slippage, is preferably used.

[0044] The weave density of the woven fabric in the artificial leather is preferably 70 threads / 2.54 cm or more and 120 threads / 2.54 cm or less for both the warp and weft. Having a weave density of 70 threads / 2.54 cm or more, preferably 80 threads / 2.54 cm or more, results in an artificial leather with excellent shape retention. On the other hand, having a weave density of 120 threads / 2.54 cm or less, preferably 110 threads / 2.54 cm or less, results in an artificial leather with a soft texture, as well as preventing the entanglement of the nonwoven fabric fibers when the nonwoven fabric and the woven fabric are entangled and integrated by needle punching. This increases the number of nonwoven fabric fibers penetrating the woven fabric, resulting in an artificial leather with sufficient nap on both sides, resulting in an elegant appearance.

[0045] [Fiber base material] The fibrous substrate used in the present invention comprises the nonwoven fabric and a woven fabric. Preferably, the nonwoven fabric and the woven fabric are entangled together. Here, the entangled nonwoven fabric and the woven fabric refer to a structure in which the fibers constituting the nonwoven fabric and the fibers constituting the woven fabric are entangled and exist as a single sheet.

[0046] [Polymer elastic material] The polymeric elastomer constituting the artificial leather of the present invention serves as a binder that holds the ultrafine fibers together in the artificial leather. Therefore, to give the artificial leather a softer feel, it is preferable to use polyurethane, styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), acrylic resin, etc. as the polymeric elastomer. Among these, using polyurethane as the main component is more preferred. The use of polyurethane results in artificial leather with a rich feel, a leather-like appearance, and physical properties that are durable for practical use. In this specification, "main component" means that the mass of polyurethane is greater than 50% by mass of the total mass of the polymeric elastomer.

[0047] When polyurethane is used in the present invention, either organic solvent-based polyurethane, which is used in a dissolved state in an organic solvent, or polyurethane having hydrophilic groups, which is used in a dispersed state in water, can be used. However, polyurethane having hydrophilic groups is preferably used because it has a lower viscosity than organic solvent-based polyurethane, the polyurethane surface can be ground off by light buffing, and the fabric can be raised without being damaged.

[0048] First, in the present invention, "having a hydrophilic group" refers to "having a group having active hydrogen", and specific examples of the group having active hydrogen include a hydroxyl group, a carboxyl group, a sulfonic acid group, an amino group, etc., and from the viewpoint of reactivity with a crosslinking agent having a carbodiimide group, which will be described later, it is preferable that the compound has a hydroxyl group or a carboxyl group.

[0049] This polyurethane having a hydrophilic group can be obtained by reacting a polymer polyol, an organic diisocyanate, and an active hydrogen-containing compound having a hydrophilic group to form a hydrophilic prepolymer, and then adding and reacting a chain extender to obtain a polyurethane precursor, which is then reacted with a crosslinking agent. These will be described in detail below.

[0050] (1) High molecular weight polyol Examples of the polymer polyol preferably used in the present invention include polyether polyols, polyester polyols, and polycarbonate polyols.

[0051] First, examples of polyether polyols include polyols obtained by addition polymerization of monomers such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, epichlorohydrin, and cyclohexylene using polyhydric alcohols or polyamines as initiators, and polyols obtained by ring-opening polymerization of the above-mentioned monomers using protonic acids, Lewis acids, cationic catalysts, etc. Specific examples include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, etc., and copolymer polyols combining these.

[0052] Next, examples of polyester polyols include polyester polyols obtained by condensing various low molecular weight polyols with polybasic acids, and polyols obtained by open polymerization of lactones.

[0053] Examples of low-molecular-weight polyols used in polyester polyols include 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.

[0054] On the other hand, examples of polybasic acids used in polyester 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.

[0055] Examples of polycarbonate-based polyols include compounds obtained by reacting a polyol with a carbonate compound, such as a polyol with a dialkyl carbonate or a polyol with a diaryl carbonate.

[0056] The polyol used in the polycarbonate polyol can be a low-molecular-weight polyol used in the polyester polyol. On the other hand, the dialkyl carbonate can be dimethyl carbonate or diethyl carbonate, and the diaryl carbonate can be diphenyl carbonate.

[0057] The number-average molecular weight of the polymer polyol preferably used in the present invention is preferably 500 or more and 5000 or less. When the number-average molecular weight of the polymer polyol is 500 or more, preferably 1500 or more, the artificial leather has a soft feel. When the number-average molecular weight is 5000 or less, preferably 4000 or less, the strength of the polyurethane having hydrophilic groups used as a binder can be easily maintained.

[0058] (2) Organic diisocyanate The organic diisocyanates used in the present invention include aromatic diisocyanates having 6 to 20 carbon atoms (excluding carbon atoms in NCO groups, the same applies hereinafter), aliphatic diisocyanates having 2 to 18 carbon atoms, alicyclic diisocyanates having 4 to 15 carbon atoms, araliphatic diisocyanates having 8 to 15 carbon atoms, modified products of these diisocyanates (carbodiimide modified products, urethane modified products, uretdione modified products, etc.), and mixtures of two or more of these.

[0059] Specific examples of the aromatic diisocyanate having 6 or more and 20 or less carbon atoms include 1,3- and / or 1,4-phenylene diisocyanate, 2,4- and / or 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. Among these, it is preferable to use MDI, which has excellent flexibility when made into a polyurethane having a hydrophilic group.

[0060] Specific examples of the aliphatic diisocyanate 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-diisocyanatomethyl caproate, bis(2-isocyanatoethyl)carbonate, and 2-isocyanatoethyl-2,6-diisocyanatohexaate.

[0061] Specific examples of the alicyclic diisocyanate having 4 to 15 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. Of these, it is preferable to use dicyclohexylmethane-4,4'-diisocyanate, which has excellent durability when made into a polyurethane having a hydrophilic group.

[0062] Specific examples of the aromatic aliphatic diisocyanate having 8 to 15 carbon atoms include m- and / or p-xylylene diisocyanate, and α,α,α',α'-tetramethylxylylene diisocyanate.

[0063] (3) Compounds containing active hydrogen components with hydrophilic groups The active hydrogen component-containing compound having a hydrophilic group preferably used in the present invention includes a compound containing active hydrogen and one or more functional groups selected from a nonionic group, an anionic group, and a cationic group. These active hydrogen component-containing compounds can also be used in the form of a salt neutralized with a neutralizing agent. The use of this active hydrogen component-containing compound having a hydrophilic group can improve the stability of the aqueous dispersion used in the manufacturing method of artificial leather.

[0064] Examples of compounds having a nonionic group and active hydrogen include compounds that contain two or more active hydrogen components or two or more isocyanate groups and have a polyoxyethylene glycol group or the like with a molecular weight of 250 to 9000 in the side chain, and triols such as trimethylolpropane and trimethylolbutane.

[0065] Examples of compounds 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 derivatives thereof; sulfonic acid group-containing compounds such as 1,3-phenylenediamine-4,6-disulfonic acid and 3-(2,3-dihydroxypropoxy)-1-propanesulfonic acid, and derivatives thereof; and salts of these compounds neutralized with a neutralizing agent.

[0066] Examples of compounds containing a cationic group and active hydrogen include tertiary amino group-containing compounds such as 3-dimethylaminopropanol, N-methyldiethanolamine, and N-propyldiethanolamine, and derivatives thereof.

[0067] (4) Chain extender Examples of chain extenders used in the present invention include water, low molecular weight diols such as ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,4-butanediol, 1,6-hexanediol, diethylene glycol, and neopentyl glycol, alicyclic diols such as 1,4-bis(hydroxymethyl)cyclohexane, aromatic diols such as 1,4-bis(hydroxyethyl)benzene, aliphatic diamines such as ethylenediamine, alicyclic diamines such as isophoronediamine, aromatic diamines such as 4,4-diaminodiphenylmethane, aromatic aliphatic diamines such as xylenediamine, alkanolamines such as ethanolamine, hydrazine, dihydrazides such as adipic acid dihydrazide, and mixtures of two or more of these.

[0068] Of these, preferred chain extenders are water, low molecular weight diols, and aromatic diamines, and more preferred are water, ethylene glycol, 1,4-butanediol, 4,4'-diaminodiphenylmethane, and mixtures of two or more of these.

[0069] (5) Structure of polyurethane precursor As described above, the polyurethane precursor used in the present invention is prepared by reacting the polymer polyol, 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.

[0070] (6) Crosslinking agent The crosslinking agent used in the present invention may have two or more reactive groups in the molecule that can react with the reactive group introduced into the polyurethane precursor, and specific examples include polyisocyanate crosslinking agents such as water-soluble isocyanate compounds and blocked isocyanate compounds, oxazoline crosslinking agents, carbodiimide crosslinking agents, melamine crosslinking agents, etc. One type of crosslinking agent may be used alone, or two or more types may be used in combination.

[0071] The water-soluble isocyanate compound has two or more isocyanate groups in the molecule, and examples thereof include the above-mentioned organic polyisocyanate-containing compounds. Commercially available products include the Bayhydur (registered trademark) series and Desmodur (registered trademark) series manufactured by Bayer MaterialScience Co., Ltd.

[0072] A blocked isocyanate compound has two or more blocked isocyanate groups in the molecule. The blocked isocyanate group refers to an 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. Commercially available products include the "Elastron" (registered trademark) series from Dai-ichi Kogyo Seiyaku Co., Ltd., the "Duranate" (registered trademark) series from Asahi Kasei Corporation, and the "Takenate" (registered trademark) series from Mitsui Chemicals, Inc.

[0073] Examples of oxazoline crosslinking agents include compounds having two or more oxazoline groups (oxazoline skeletons) in the molecule. Commercially available products include the "Epocross" (registered trademark) series manufactured by Nippon Shokubai Co., Ltd.

[0074] Examples of carbodiimide crosslinking agents include compounds having two or more carbodiimide groups in the molecule. Commercially available products include the "Carbodilite" (registered trademark) series manufactured by Nisshinbo Chemical Inc.

[0075] Among these, it is particularly preferable to use a carbodiimide compound, which gives a polyurethane having a hydrophilic group obtained after the reaction that is particularly excellent in durability and flexibility.

[0076] (7) Structure of polyurethane having hydrophilic groups The polyurethane having a hydrophilic group is preferably a polyether polyurethane containing a component derived from a polyether polyol and / or a polycarbonate polyurethane containing a component derived from a polycarbonate polyol.

[0077] From the viewpoint of flexibility, polyether polyurethane is preferable. When the polyurethane having a hydrophilic group is a polyether polyurethane, that is, when it contains a constituent component derived from a polyether polyol, the degree of freedom of the ether bond is high, and therefore the glass transition temperature is low and the cohesive force is weak, and therefore the polyurethane having a hydrophilic group has excellent flexibility.

[0078] On the other hand, from the viewpoint of durability, polycarbonate-based polyurethanes are preferred. When the polyurethane having a hydrophilic group is a polycarbonate-based polyurethane, that is, when it contains a constituent component derived from a polycarbonate-based polyol, the high cohesive force of the carbonate group can be used to provide a polyurethane having a hydrophilic group that is excellent in water resistance, heat resistance, weather resistance, and mechanical properties.

[0079] The constitution of the polyurethane having a hydrophilic group can be adjusted appropriately depending on the required properties, and polyether polyurethane or polycarbonate polyurethane may be used alone or in combination.

[0080] The constituent components of the polyurethane having hydrophilic groups can be confirmed (that the polyurethane having hydrophilic groups contains a component derived from polyester polyol, and that the polyurethane having hydrophilic groups further contains a component derived from polycarbonate polyol) by dissolving the fibrous substrate that constitutes the artificial leather and analyzing the insoluble matter (polyurethane having hydrophilic groups) using infrared spectroscopic analysis (the analytical instrument used is the FT / IR 4000 series manufactured by JASCO Corporation or an infrared spectroscopic analyzer with equivalent performance) or pyrolysis GC / MS analysis (the analytical instrument used is the GCMS-QP5050A manufactured by Shimadzu Corporation or a pyrolysis GC / MS analyzer with equivalent performance).

[0081] To dissolve the fiber base material constituting the artificial leather, it is necessary to dissolve the polymer constituting the fiber base material in a solvent that dissolves the polymer constituting the fiber base material but does not dissolve the polyurethane component. For example, solvents that can dissolve polyester include m-cresol and hexafluoroisopropanol, but it is preferable to use hexafluoroisopropanol, which can be handled at room temperature.

[0082] The polyurethane having a hydrophilic group used in the present invention preferably has an N-acylurea bond and / or an isourea bond. The N-acylurea bond and / or the isourea bond is formed by the reaction of the hydrophilic group with a crosslinking agent having a carbodiimide group, and by forming a crosslinked structure in the polyurethane having a hydrophilic group, the durability of the polyurethane having a hydrophilic group can be improved.

[0083] The presence of the N-acylurea group or isourea group in the polyurethane having a hydrophilic group can be analyzed by subjecting a cross section of the artificial leather to, for example, a mapping process such as time-of-flight secondary ion mass spectrometry (TOF-SIMS analysis) (the analytical instrument used may be, for example, the "TOF.SIMS 5" manufactured by ION-TOF or a TOF-SIMS analyzer having equivalent performance) or infrared spectroscopy (the analytical instrument used may be, for example, the "FT / IR 4000 series" manufactured by JASCO Corporation or an infrared spectroscopy analyzer having equivalent performance).

[0084] The artificial leather of the present invention preferably contains an elastomer content of 15% by mass or more and 25% by mass or less. A content of elastomer of 15% by mass or more, preferably 18% by mass or more, results in an artificial leather with excellent abrasion resistance. On the other hand, a content of elastomer of 25% by mass or less, preferably 22% by mass or less, results in an artificial leather with a soft feel.

[0085] In the present invention, the content of the polymeric elastomer is measured and calculated by the following method. (1) Randomly cut a 5cm x 5cm test piece from the artificial leather, and measure the mass (M X ) and perform this operation three times in different locations. (2) The test piece is immersed in a solvent capable of dissolving the fibrous substrate, thereby dissolving the fibrous substrate from the artificial leather. For example, when the fibrous substrate is made of a polyester resin, it is preferable to use hexafluoroisopropanol as the solvent. (3) The insoluble component (polymeric elastomer) of (2) was dried in a dryer at 100°C and the mass (M A ) is measured, and then the content ratio (mass%) of the polymer elastomer is calculated using the following formula: Content of polymer elastomer (mass%) = (M A / M X )×100...(formula) (4) The arithmetic mean value (% by mass) of the three points obtained is calculated and rounded off to the first decimal place to obtain the content (% by mass) of the polymer elastomer.

[0086] Furthermore, the polymeric elastomer may contain various additives depending on the purpose, such as flame retardants such as "phosphorus-based, halogen-based, and inorganic-based" antioxidants, "phenol-based, sulfur-based, and phosphorus-based" antioxidants, ultraviolet absorbers such as "benzotriazole-based, benzophenone-based, salicylate-based, cyanoacrylate-based, and oxalic acid anilide-based" ultraviolet absorbers, "hindered amine-based and benzoate-based" light stabilizers, hydrolysis-resistant stabilizers such as polycarbodiimide, plasticizers, antistatic agents, surfactants, coagulation adjusters, and dyes.

[0087] [Artificial leather] The artificial leather of the present invention includes the fibrous base material and the polymer elastomer. When the surface of the artificial leather farther from the woven fabric is designated as a first surface and the surface opposite the first surface is designated as a second surface, both the first surface and the second surface have nap. As shown in Figure 1, the artificial leather (10) of the present invention is composed of a first surface (11) having nap, a layer (12) made of ultrafine fibers and a polymer elastomer, a layer (13) made of ultrafine fibers, a woven fabric, and a polymer elastomer, and a second surface (14) having nap.

[0088] The artificial leather of the present invention has an average nap length of 200 μm or more and 500 μm or less on the first surface. Having an average nap length of 200 μm or more, preferably 220 μm or more, results in an artificial leather with an excellent feel. On the other hand, having an average nap length of 500 μm or less, preferably 450 μm or less, can suppress deterioration in surface quality due to fluffing of the nap, resulting in an artificial leather with an elegant suede-like surface quality.

[0089] The artificial leather of the present invention has a coefficient of variation of nap length of 30% or less on the first surface. By setting the coefficient of variation of nap length to 30% or less, preferably 20% or less, the artificial leather has a more uniform and elegant surface quality.

[0090] The average value of the nap length on the first surface can be set within the above range by adjusting the grit size of the sandpaper used in the process of forming the first surface and the amount of lubricant such as silicone emulsion applied.

[0091] The artificial leather of the present invention has an average nap length of 500 μm or more and 1000 μm or less on the second surface. By setting the average nap length to 500 μm or more, preferably 600 μm or more, the artificial leather has a superior feel and appearance, and does not give the impression that the surface area is made of woven fabric. On the other hand, by setting the average nap length to 1000 μm or less, preferably 900 μm or less, deterioration of surface quality due to entanglement of ultrafine fibers can be suppressed, resulting in an artificial leather with elegant surface quality.

[0092] The artificial leather of the present invention has a coefficient of variation of nap length of 30% or less on the second surface. By having a coefficient of variation of nap length of 30% or less, preferably 20% or less, the artificial leather has a more uniform and elegant surface quality.

[0093] The artificial leather of the present invention has a nap coverage of 97.5% or more on the second surface. By having a nap coverage of 97.5% or more, preferably 98.0% or more, the artificial leather has an elegant surface quality without the fabric being exposed on the surface. In addition, the surface smoothness of the artificial leather is improved, resulting in an artificial leather with an excellent feel.

[0094] On the second surface, the nap length and nap coverage can be set within the above ranges by adjusting the amount of solids derived from the mixed oil of silicone and non-silicone fiber oil described below that adheres to the ultrafine fiber-developing fiber, the grit size of the sandpaper used in the process of forming the second surface, the amount of lubricant such as silicone emulsion, etc.

[0095] In the present invention, the average value of the nap length and the coefficient of variation of the nap length of the artificial leather are calculated by the following method. (1) Using a lint brush or the like, the nap of the artificial leather is raised and a thin section 1 mm thick is prepared in the cross-sectional direction of the surface perpendicular to the longitudinal direction of the artificial leather. (2) Observe the cross section of the artificial leather using a scanning electron microscope (SEM) at 80x magnification. (3) In the SEM image taken, the height of the napped portion (layer consisting only of ultrafine fibers) is measured at 10 points at 200 μm intervals across the width of the cross section of the artificial leather. (4) The average value (arithmetic mean) and coefficient of variation are calculated for the height of the napped portion (layer consisting only of ultrafine fibers) measured at 10 points. In the present invention, the average value of the nap length is the value (μm) rounded to the nearest whole number, and the coefficient of variation is the value (%) calculated by the following formula rounded to the nearest whole number: Coefficient of variation of standing hair length (%) = [(standard deviation of standing hair length) / (arithmetic mean of standing hair length)] × 100 (formula).

[0096] The standing hair coverage was measured by magnifying the standing hair surface by 30 to 90 times using SEM to determine the presence of standing hairs, and analyzing the total area of ​​9 mm2 using image analysis software (e.g., "ImageJ" from the National Institutes of Health (NIH)). 2 The ratio of the total area of ​​the napped portion per unit area was calculated and used as the napped coverage rate. The total area ratio can be calculated by using image analysis software to binarize the captured SEM image by setting a threshold of 128 out of 256 gradations, with white being 255 and black being 0, for the napped and non-napped portions. In addition, when calculating the napped coverage rate, if a material that is not napped is calculated as napped and has a large impact on the napped coverage rate, the image can be manually edited and the color tone of the non-napped material set to 0, and that part can be calculated as a non-napped portion.

[0097] An example of image analysis software is the image analysis software "ImageJ." However, the image analysis software is not limited to the image analysis software "ImageJ," as long as it is image processing software that has the function of calculating the area ratio of specified pixels. Note that the image processing software "ImageJ" is a commonly used software and was developed by the National Institutes of Health in the United States. The image processing software "ImageJ" has the function of identifying necessary areas in an imported image and performing pixel analysis.

[0098] The apparent density of the artificial leather of the present invention is 0.20 g / cm 3 More than 0.40g / cm 3 The apparent density of the artificial leather is preferably 0.20 g / cm or less. 3 or more, preferably 0.25 g / cm 3 When the apparent density is 0.40 g / cm or more, the artificial leather has excellent abrasion resistance. 3 or less, preferably 0.35 g / cm 3 By satisfying the following conditions, the artificial leather has a soft texture and excellent breathability.

[0099] The apparent density of the artificial leather of the present invention can be adjusted to the above range by applying a solid component derived from a mixed oil of silicone and non-silicone textile oils, which will be described later, to the ultrafine fiber developing fibers.

[0100] In the present invention, the apparent density of the artificial leather is a value (g / cm) calculated using the following formula after measuring the thickness and mass per unit area of ​​the artificial leather using the methods specified in "6.1.1 (Thickness Method A)" ​​and "6.2 (Mass per unit area)" of "General Nonwoven Fabric Testing Methods" in "JIS L1913:2010": 3 ) is the value obtained by rounding to three decimal places. Apparent density of artificial leather (g / cm 3 ) = Mass per unit area of ​​artificial leather (g / cm 2 ) / Thickness of artificial leather (cm) ···(formula).

[0101] The artificial leather of the present invention has raised nap on both sides and an elegant appearance, making it suitable for a wide range of applications, including clothing, miscellaneous goods, shoe and bag applications, vehicle interior materials, seats, CD curtains, DVD curtains, polishing pad substrates, various polishing cloths, wiping cloths, and other industrial materials. It is particularly suitable for clothing and bags. It can also be used for everyday items such as shoe uppers and trims, wallets, and accessories, without being limited to clothing and bags.

[0102] Among these, clothing containing the artificial leather is preferred because it has raised fabric on both sides, excellent breathability, and an elegant appearance. It is particularly noteworthy that it can create a high-quality, luxurious feel when used on both sides or when used on products where the backside is visible during use. Examples of such clothing include tops such as T-shirts, polo shirts, dress shirts, blouses, wrap tops, cut-and-sew tops, sweaters, vests, hoodies, sweatshirts, turtlenecks, cardigans, tank tops, and tube tops; outerwear such as coats, blazers, jackets, windbreakers, cloaks, capes, aprons, and mantles; trousers such as slacks, jeans, and shorts; skirts; dresses such as cocktail dresses, one-piece dresses, and gowns; formal wear, suits, uniforms, underwear, hats, scarves, and ties (including linings for the above clothing, and clothing materials and accessories such as buttons and pockets).

[0103] Bags containing the artificial leather are also preferred because they have raised fabric on both sides, excellent breathability, and an elegant appearance, and can be used for bags such as Boston bags, overnight cases, briefcases, duffel bags, school bags, lycée bags, sports bags, bonsacks, gusset bags, envelope bags, clutch bags, vanity bags, shoulder bags, waist pouches, tote bags, bucket bags, daypacks, and knapsacks.

[0104] [Manufacturing method for artificial leather] The method for producing an artificial leather of the present invention includes the steps of obtaining a nonwoven fabric composed of ultrafine fiber-developing fibers, which are islands-in-sea composite fibers in which the sea component is an alkali-soluble resin, and to which solids derived from a mixed oil solution of silicone and non-silicone fiber oil solution are adhered, and the amount of the adhered solids is 0.30% by mass or more and 1.00% by mass or less; a step of entangling and integrating the nonwoven fabric and the woven fabric to obtain a fibrous substrate; a step of providing a polymeric elastomer to the fibrous base material to obtain a polymeric elastomer-coated sheet; a step of treating the polymeric elastomer-attached sheet with an alkali to produce ultrafine fibers having an average single fiber diameter of 1.0 μm or more and 10.0 μm or less from the ultrafine fiber-producing fibers, thereby obtaining an ultrafine fiber sheet; a step of heat-treating the ultrafine fiber sheet at an atmospheric temperature of 150°C or higher and 200°C or lower for 5 minutes or longer and 20 minutes or shorter to obtain a heat-treated sheet; grinding the surface of the heat treatment sheet away from the fabric to form a first surface having nap; grinding or scraping the other surface to form a second surface having nap; A method for producing artificial leather, comprising: On the first surface, the average value of the nap length is 200 μm or more and 500 μm or less, and the coefficient of variation of the nap length is 30% or less, On the second surface, the nap coverage is 97.5% or more, the average value of the nap length is 500 μm or more and 1000 μm or less, and the coefficient of variation of the nap length is 30% or less. This is a method for manufacturing artificial leather.

[0105] Details are explained below.

[0106] <Process for obtaining nonwoven fabric> In this process, a nonwoven fabric is obtained which is composed of islands-in-sea composite fibers in which the sea component is an alkali-soluble resin, and ultrafine fiber-developing fibers in which the amount of silicone and oil mixture attached is 0.30% by mass or more and 1.00% by mass or less.

[0107] As the ultrafine fiber-forming fiber, it is preferable to use an islands-in-sea type composite fiber in which the sea part and island part are made of two thermoplastic resin components (two or three components when the island fiber is a core-sheath composite fiber) with different solvent solubility, and the sea part is converted into ultrafine fibers by dissolving and removing it using a solvent or the like, because this can provide appropriate gaps between the island parts, i.e., between the ultrafine fibers inside the fiber bundle, when the sea part is removed, from the perspective of the texture and surface quality of the artificial leather.

[0108] Here, "different solvent solubility" means that the solubility of one thermoplastic resin in a solvent such as an organic solvent or an aqueous solution such as an alkaline aqueous solution used to remove the other thermoplastic resin from the ultrafine fiber-forming fiber is 100 times or more different. Because of this difference, for example, an alkali-soluble resin that is easily soluble in an alkaline aqueous solution will dissolve within 5 minutes when immersed in a 5% sodium hydroxide aqueous solution, whereas the other thermoplastic resin used in combination will not dissolve in the above solution for more than 10 minutes. This makes it easy to obtain ultrafine fibers.

[0109] For islands-in-sea type composite fibers, a method using a polymer mutually aligned body in which two components, a sea component and an island component, are mutually aligned and spun using an islands-in-sea type composite spinneret (three components when the island components are core-sheath composite fibers) is preferred from the viewpoint of obtaining ultrafine fibers with a uniform single fiber diameter.

[0110] The alkali-soluble resin used for the sea part of the islands-in-sea type composite fiber is preferably a copolymer polyester from the viewpoints of spinnability and ease of dissolution by alkali treatment. Furthermore, by using a copolymer polyester for the sea part, the frictional force between the islands-in-sea type composite fibers is reduced and the flexibility of the fibers is improved. Therefore, when the nonwoven fabric and the woven fabric are entangled and integrated by needle punching, the number of fibers of the nonwoven fabric penetrating the woven fabric increases, and when the nonwoven fabric is made into artificial leather, sufficient nap is formed on both sides, resulting in an elegant appearance.

[0111] When a copolymer polyester is used, it is preferable to use a copolymer polyester in which 3 mol % to 15 mol % of sodium 5-sulfoisophthalate is copolymerized as a copolymerization component, where the total amount of dicarboxylic acid components is taken as 100 mol %. By setting the copolymerization amount of sodium 5-sulfoisophthalate component to 3 mol % or more, preferably 5 mol % or more, sufficient alkali elution properties can be obtained. On the other hand, by setting the copolymerization amount of sodium 5-sulfoisophthalate component to 15 mol % or less, preferably 13 mol % or less, thickening of the polyester is suppressed, and fiber breakage during spinning into islands-in-sea composite fibers is reduced.

[0112] The alkali-soluble resin is also preferably a copolymerized polyester copolymerized with a polyalkylene glycol having a number-average molecular weight of 500 or more and 3500 or less. More preferably, the resin is a copolymerized polyester copolymerized with a polyalkylene glycol having a number-average molecular weight of 700 or more and 3000 or less. When the number-average molecular weight of the polyalkylene glycol is within the above range, the flexibility of the islands-in-sea type composite fiber is improved, and when the nonwoven fabric and woven fabric are entangled and integrated by needle punching, the number of fibers of the nonwoven fabric penetrating the woven fabric increases, making it possible to produce an artificial leather having sufficient nap on both sides.

[0113] The number-average molecular weight of polyalkylene glycol is measured and calculated by the following method. Specifically, it is measured using a gel permeation chromatography apparatus (GPC, for example, Tosoh Corporation's "HLC-8220" or a GPC apparatus with equivalent performance) at a column temperature of 40°C, a flow rate of 1.0 mL / min, and tetrahydrofuran as an eluent. A calibration curve is prepared using polystyrene standards as standard samples, and the number-average molecular weight is determined by comparison with this curve.

[0114] The copolymerization amount of polyalkylene glycol in the copolymer polyester is preferably 0.1% by mass or more and 15.0% by mass or less, when the total amount of the copolymer polyester is taken as 100% by mass. By making the copolymerization amount of polyalkylene glycol 0.1% by mass or more, preferably 1.5% by mass or more, the alkali elution property becomes good. On the other hand, by making the copolymerization amount of polyalkylene glycol 15.0% by mass or less, preferably 12.0% by mass or less, the effect of preventing yarn breakage during spinning of the islands-in-sea type composite fiber is achieved.

[0115] Examples of polyalkylene glycols include polyethylene glycol, polypropylene glycol, and polybutylene glycol, with polyethylene glycol being preferred due to its ease of use and its ability to be reduced in weight in an alkaline aqueous solution.

[0116] The copolymer polyester preferably contains a polyethylene terephthalate polyester having ethylene terephthalate units as a main repeating unit as one component, and may be a polyester in which a portion of the terephthalic acid component is replaced with another bifunctional carboxylic acid component, or a polyester in which a portion of the ethylene glycol component is replaced with another polyol component.

[0117] Preferred examples of the difunctional carboxylic acid other than terephthalic acid used in the present invention include aromatic, aliphatic, and alicyclic difunctional carboxylic acids such as isophthalic acid, naphthalenedicarboxylic acid, diphenyldicarboxylic acid, adipic acid, sebacic acid, and 1,4-cyclohexanedicarboxylic acid. Preferred examples of the polyol compound other than ethylene glycol include aliphatic, alicyclic, and aromatic polyol compounds such as tetramethylene glycol, hexamethylene glycol, cyclohexane-1,4-dimethanol, neopentyl glycol, bisphenol A, and bisphenol S.

[0118] The alkali-soluble resin used for the sea part of the islands-in-sea type composite fiber may contain inorganic particles such as titanium oxide particles, lubricants, pigments, heat stabilizers, ultraviolet absorbers, conductive agents, heat storage agents, antibacterial agents, and the like, depending on various purposes.

[0119] The mass ratio of the sea component to the island component in the islands-in-sea type composite fiber used in the present invention is preferably 10% by mass or more and 80% by mass or less, in terms of the mass ratio of the sea component to the islands-in-sea type composite fiber. When the mass ratio of the sea component is preferably 10% by mass or more, more preferably 15% by mass or more, the island component fibers are easily and sufficiently ultrafine-thinned. Furthermore, when the mass ratio of the sea component is preferably 80% by mass or less, more preferably 70% by mass or less, the proportion of eluted components is reduced, thereby improving productivity.

[0120] In the present invention, solids derived from a mixed oil solution of silicone and non-silicone-based textile oil are adhered to the ultrafine fiber-developing fiber, and the amount of the adhered solids is 0.30% by mass or more and 1.00% by mass or less. By making the amount of solids derived from the mixed oil solution of silicone and non-silicone-based textile oil adhered to the ultrafine fiber-developing fiber 0.30% by mass or more, preferably 0.35% by mass or more, and more preferably 0.40% by mass or more, friction between the ultrafine fiber-developing fibers and between the ultrafine fiber-developing fibers and the woven fabric is reduced, and when the nonwoven fabric and the woven fabric are entangled and integrated by needle punching, the number of fibers of the nonwoven fabric that penetrate the woven fabric increases, and when made into artificial leather, sufficient nap is provided on both sides, resulting in an elegant appearance. Furthermore, by keeping the amount of solids derived from the mixed oil of silicone and non-silicone fiber oil adhered to the ultrafine fiber-forming fiber to 1.00% by mass or less, preferably 0.90% by mass or less, and more preferably 0.80% by mass or less, when the nonwoven fabric and woven fabric are entangled and integrated by needle punching or the like, the friction between the fibers of the nonwoven fabric and the barbs is not hindered, and when the nonwoven fabric and woven fabric are entangled and integrated by needle punching without separating from the barbs, an increase in the number of fibers of the nonwoven fabric that penetrate the woven fabric can be achieved, and when made into artificial leather, sufficient nap can be provided on both sides, resulting in an elegant appearance.

[0121] The amount of solids derived from the mixed oil of silicone and non-silicone fiber oil that adheres to the ultrafine fiber-developing fiber can be set within the above range by adjusting the amount of the mixed liquid of silicone and non-silicone fiber oil that is applied to the ultrafine fiber-developing fiber and the solids concentration in the mixed liquid, etc.

[0122] Of the solids derived from the mixed oil of silicone and non-silicone fiber oil adhering to the ultrafine fiber developing fiber, the proportion of silicone is preferably 30% by mass or more and 70% by mass or less. By making the proportion of silicone preferably 30% by mass or more, more preferably 40% by mass or more, friction between the ultrafine fiber developing fibers is reduced, and when the nonwoven fabric and woven fabric are entangled and integrated by needle punching, the number of fibers of the nonwoven fabric penetrating the woven fabric increases, and when made into artificial leather, sufficient nap is provided on both sides, resulting in an elegant appearance. Furthermore, by making the proportion of silicone in the solids derived from the mixed oil of silicone and non-silicone-based textile oil adhered to the ultrafine fiber-developing fiber preferably 70% by mass or less, more preferably 60% by mass or less, the antistatic properties derived from the solids derived from the mixed oil with non-silicone-based textile oil are improved, the ultrafine fiber-developing fiber can be opened more uniformly, and when the nonwoven fabric and woven fabric are entangled and integrated by needle punching, the fibers of the nonwoven fabric can penetrate the woven fabric more uniformly, and when made into artificial leather, it can have sufficient nap on both sides and have an elegant appearance. Furthermore, by mixing the solids derived from the mixed oil of silicone and non-silicone-based textile oil in the above proportions, the dispersibility of the silicone can be improved and the silicone can be adhered uniformly to the raw cotton, which makes it easier to reduce friction between the ultrafine fiber-developing fibers and makes it easier to achieve the above-mentioned effects more efficiently.

[0123] The method for applying the mixed oil of silicone and non-silicone-based textile oil to ultrafine fiber-forming fibers may be any of a method in which the mixed liquid of silicone and non-silicone-based textile oil is sprayed onto fibers or nonwoven fabric with a spray or the like, or a method in which fibers are impregnated with the mixed liquid and then squeezed out. When the fibers are subjected to a drawing process, it is preferable to apply the mixed oil of silicone and non-silicone-based textile oil after the drawing process in order to ensure a more uniform amount of adhesion of the mixed oil of silicone and non-silicone-based textile oil to the raw cotton.

[0124] The solids concentration in the mixed solution is preferably 2% by mass or more and 50% by mass or less. By making it preferably 2% by mass or more, more preferably 5% by mass or more, the drying time after application of the mixed solution can be shortened, thereby improving productivity. Furthermore, by making the solids concentration preferably 50% by mass or less, more preferably 40% by mass or less, it becomes easier to control the amount of adhesion to the ultrafine fiber development type fiber.

[0125] Specific preferred examples of the silicone used in the present invention include dimethyl silicone, methylphenyl silicone, epoxy-modified silicone, amino-modified silicone, methylhydrogen silicone, alkyl-modified silicone, silicone polyether copolymer, and combinations thereof. Among these, dimethyl silicone reduces friction between ultrafine fiber-developing fibers when entangling the ultrafine fiber-developing fibers to obtain a nonwoven fabric, increases the number of fibers of the nonwoven fabric that penetrate the woven fabric when the nonwoven fabric and woven fabric are entangled and integrated by needle punching, and provides an elegant appearance when made into artificial leather by providing sufficient nap on both surfaces.

[0126] Furthermore, preferred specific examples of solids derived from the non-silicone textile oil used in the present invention include aliphatic esters, polyhydric alcohol esters, ether esters, polyethers, and organic phosphoric acid compounds, such as polyoxyalkylene alkyl ethers, polyoxyalkylene alkylphenyl ethers, polyoxyalkylene alkyl esters, polyoxyalkylene castor oil, polyoxyalkylene alkylaminoether sorbitan monolaurate, sorbitan triolate, glycerin monolaurate, diglycerin dilaurate, polyoxyalkylene polyhydric alcohol fatty acid esters, organic fatty acid salts, organic phosphates, lauryltrimethylammonium ethosulfate, and octyldimethylammonio acetate, and combinations thereof. Among these, organic phosphoric acid compounds have high antistatic properties, which can suppress fiber aggregation due to static electricity, resulting in an elegant appearance when made into artificial leather.

[0127] The amount of solid matter derived from the mixed oil solution of silicone and non-silicone fiber oil solution attached to the ultrafine fiber developing fiber is measured and calculated by the following method. (1) Weigh 2 g of the ultrafine fiber-developing fiber to the third decimal point (M F ) and extracted with a toluene / methanol mixture (30% by mass / 70% by mass) for 15 minutes. (2) Evaporate the toluene / methanol mixture and determine the weight of the remaining solid (M O ) to three decimal places. (3) The value (mass%) calculated by the following formula is rounded to two decimal places to determine the amount of solids derived from the mixed oil of silicone and non-silicone fiber oil attached to the ultrafine fiber developing fiber. The amount (mass%) of solids derived from the mixed oil of silicone and non-silicone fiber oil attached to the ultrafine fiber-forming fiber = (M O / M F )×100...(formula).

[0128] The non-silicone textile oil used in the present invention may further contain an antistatic agent, a surfactant, and mineral oil as a diluent, as long as the effects of the present invention are not impaired.

[0129] As described above, the nonwoven fabric of the present invention can be in the form of either a long-fiber nonwoven fabric or a short-fiber nonwoven fabric. However, a short-fiber nonwoven fabric is preferred because it results in a nonwoven fabric with more fibers oriented in the thickness direction of the artificial leather than a long-fiber nonwoven fabric, resulting in a high fiber density and excellent uniformity of fiber orientation, which makes it possible to obtain a highly dense feel on the surface of the artificial leather when it is brushed.

[0130] When a staple fiber nonwoven fabric is used as the nonwoven fabric, the obtained ultrafine fiber developing fibers are preferably subjected to crimping processing and then cut to a predetermined length to obtain raw cotton. The crimping processing and cutting processing can be carried out by known methods.

[0131] Next, the obtained raw cotton is made into a fiber web using a cross wrapper or the like. The obtained fiber web is then entangled to obtain a nonwoven fabric. As a method for entangling the fiber web to obtain a nonwoven fabric, needle punching, water jet punching, or the like can be used. However, in order to set the surface coverage of the second surface, the average value of the nap length, and the coefficient of variation of the nap length within the above-mentioned ranges, needle punching, which has a high entanglement efficiency, is preferred.

[0132] The needles used for the needle punching preferably have one to nine needle barbs (notches) per needle. Having one or more needle barbs per needle enables efficient fiber entanglement, increasing the number of fibers penetrating the woven fabric when the nonwoven fabric and woven fabric are entangled and integrated. When the artificial leather is made, it has sufficient nap on both surfaces, resulting in an elegant appearance. On the other hand, having nine or fewer needle barbs per needle can reduce fiber damage.

[0133] The number of ultrafine fiber-developing fibers caught on the needle barb is determined by the shape of the needle barb and the diameter of the ultrafine fiber-developing fibers. Therefore, it is preferable that the needle barb shape of the needle used in needle punching has a kick-up of 0 μm to 50 μm, an undercut angle of 0° to 40°, a throat depth of 40 μm to 80 μm, and a throat length of 0.5 mm to 1.0 mm.

[0134] Needle punching rate: 1000 / cm 2 Over 8000 pieces / cm 2 It is preferable to set the number of punches to 1000 / cm or less. 2 By setting the number of punches to 8000 / cm, a dense nonwoven fabric can be obtained, and when the nonwoven fabric and woven fabric are entangled and integrated, the number of fibers of the nonwoven fabric penetrating the woven fabric increases, and when the nonwoven fabric is made into artificial leather, sufficient nap is provided on both surfaces, resulting in an elegant appearance. 2 By setting the content below, it is possible to prevent deterioration of processability, fiber damage, and reduction in strength.

[0135] When performing water jet punching, it is preferable to use water in the form of a columnar flow. Specifically, it is preferable to eject water from a nozzle having a diameter of 0.05 mm to 1.00 mm at a pressure of 2 MPa to 60 MPa.

[0136] <Step of obtaining fibrous base material> In this step, the nonwoven fabric and the woven fabric are laminated and entangled to form a fibrous substrate.

[0137] To entangle and integrate the nonwoven fabric and the woven fabric, the woven fabric can be laminated on one or both sides of the nonwoven fabric, and then the fibers of the nonwoven fabric and the woven fabric can be entangled and integrated by needle punching, water jet punching, or the like. In this case, when needle punching or water jet punching is performed in the process of obtaining the nonwoven fabric, it is preferable to perform the needle punching, etc. performed in the process of obtaining the nonwoven fabric, less force. This can prevent damage to the fibers. Furthermore, from the viewpoint of production efficiency, it is preferable to laminate the woven fabric on both sides and then cut it in half in the thickness direction in a later process to obtain two pieces of artificial leather.

[0138] Furthermore, in this process, a large number of fibers of the nonwoven fabric are penetrated through the woven fabric, and when the artificial leather is made, the number of fibers present on the surface closest to the woven fabric increases. When the nap raising treatment described below is performed, uniform nap raising can be achieved without damaging the woven fabric, resulting in an elegant appearance. As described above, the solid content derived from the mixed oil solution of silicone and non-silicone textile oil adheres to the fibers, allowing a large number of fibers of the nonwoven fabric to be penetrated through the woven fabric. In addition, it is also a preferred embodiment to use a copolymer polyester in which sodium 5-sulfoisophthalate and a polyalkylene glycol having a number average molecular weight of 500 to 3500 are copolymerized as the sea component of the islands-in-sea type composite fiber.

[0139] The apparent density of the fibrous base material is 0.15 g / cm 3 More than 0.40g / cm 3 The apparent density of the nonwoven fabric is preferably 0.15 g / cm or less. 3 More preferably, 0.20 g / cm 3 By setting the thickness to 0.40 g / cm or more, a sufficient pile length can be obtained. On the other hand, the apparent density of the nonwoven fabric is preferably 0.40 g / cm. 3 or less, more preferably 0.35 g / cm 3 By setting the above, it is possible to maintain a space for applying the polymeric elastomer, so that the polymeric elastomer is applied uniformly, and an artificial leather with excellent resilience can be obtained.

[0140] The weight of the fibrous base material is 200 g / m 2 More than 900g / m 2 The basis weight of the fibrous base material is preferably 200 g / m or less. 2 More preferably, 250 g / m 2 By setting the weight of the fibrous base material at 900 g / m or more, a sufficient nap coverage can be achieved. 2 Less than 800 g / m 2 By satisfying the following conditions, the artificial leather can be made to have excellent breathability.

[0141] It is also a preferred embodiment that the fibrous base material is subjected to a heat shrinking treatment using hot water or steam in order to improve the denseness of the fibers.

[0142] <Step of obtaining a sheet with polymeric elastomer> In this step, a polymeric elastomer is applied to the fibrous substrate to obtain a sheet with a polymeric elastomer. Specifically, a step of impregnating the fibrous substrate with a solution of a polymeric elastomer and coagulating the solution to apply the polymeric elastomer is more preferable.

[0143] Methods for fixing a polymer elastomer to a composite fibrous substrate or a fibrous substrate include a wet coagulation method in which a solution of the polymer elastomer is impregnated into the fibrous substrate and then immersed in a coagulation bath to fix it, and a dry coagulation method in which the polymer elastomer is dried to fix it. Either method can be selected as appropriate depending on the type of polymer elastomer to be applied.

[0144] Preferred solvents used when providing polyurethane as the polymeric elastomer include N,N'-dimethylformamide, dimethyl sulfoxide, and polyurethane liquids having hydrophilic groups. Among these, polyurethane liquids having hydrophilic groups are preferred from the viewpoint of environmental consideration.

[0145] When using a polyurethane liquid having hydrophilic groups, coagulation methods commonly used in this field, such as dry heat coagulation and submerged coagulation, can be applied. When using the dry heat coagulation method, it is preferable to apply the polyurethane liquid having hydrophilic groups to the fibrous substrate, followed by heat treatment at a temperature of 120°C to 180°C and dry heat coagulation to impart a polyurethane having hydrophilic groups to the fibrous substrate. Furthermore, as the submerged coagulation method, an acid coagulation method in which coagulation treatment is performed using a coagulation solvent with a pH of 1 to 3, or a hot water coagulation method in which coagulation treatment is performed using hot water at 80°C to 100°C, can be used.

[0146] The concentration of the polyurethane precursor in the polyurethane liquid having hydrophilic groups (the content of the polyurethane precursor in 100% by mass of the polyurethane liquid having hydrophilic groups) is preferably 3% by mass or more and 30% by mass or less. By setting the concentration to preferably 3% by mass or more, more preferably 5% by mass or more, the polyurethane precursor can be uniformly applied to the fibrous substrate even when the amount of polyurethane precursor applied is small. On the other hand, by setting the concentration to preferably 30% by mass or less, more preferably 15% by mass or less, the storage stability of the polyurethane liquid having hydrophilic groups can be improved.

[0147] When dry heat coagulation is used as the coagulation method, it is preferable to adjust the coagulation temperature to 55°C or higher and 80°C or lower. The coagulation temperature can be adjusted by adding an inorganic salt or the like to an aqueous polyurethane solution having hydrophilic groups, as described below. By setting the coagulation temperature to 55°C or higher, preferably 60°C or higher, gelation of the polyurethane solution having hydrophilic groups during preparation and storage can be suppressed. On the other hand, by setting the coagulation temperature to preferably 80°C or lower, more preferably 70°C or lower, coagulation of the polyurethane precursor proceeds before water evaporates from the fibrous substrate, allowing the polyurethane to form a structure that does not strongly constrain the fibers that make up the nonwoven fabric or woven fabric, thereby achieving good flexibility and resilience.

[0148] In the method for producing an artificial leather of the present invention, the polyurethane liquid having hydrophilic groups can be imparted with heat-sensitive coagulation by adding an inorganic salt to the polyurethane liquid having hydrophilic groups. In the present invention, heat-sensitive coagulation refers to the property of the polyurethane liquid having hydrophilic groups to decrease in fluidity and coagulate when it reaches a certain temperature (coagulation temperature) when heated.

[0149] In the present invention, when an inorganic salt is used as a heat-sensitive coagulant, it is preferable to use an inorganic salt containing a monovalent cation. The inorganic salt containing a monovalent cation is preferably sodium chloride and / or sodium sulfate. An inorganic salt containing a monovalent cation with a small ionic valence has little effect on the stability of the polyurethane liquid having hydrophilic groups, and by adjusting the amount added, it is possible to strictly control the coagulation temperature while ensuring the stability of the polyurethane liquid having hydrophilic groups.

[0150] Furthermore, in the present invention, the content of the monovalent cation-containing inorganic salt in the hydrophilic polyurethane liquid is preferably 10% by mass or more and 50% by mass or less relative to the polyurethane precursor. By setting the content to preferably 10% by mass or more, more preferably 20% by mass or more, and even more preferably 30% by mass or more, the ions present in large quantities in the hydrophilic polyurethane liquid act uniformly on the polyurethane precursor particles, thereby enabling rapid coagulation at a specific coagulation temperature. This allows the coagulation of the polyurethane precursor to proceed while the fibrous substrate contains a large amount of moisture, as described above, thereby achieving good flexibility and resilience. Furthermore, by adding the inorganic salt in the above-mentioned amount, the inorganic salt acts as an inhibitor against the fusion of polyurethane precursor particles, thereby suppressing the hardening of the polyurethane precursor due to the formation of a continuous coating. On the other hand, by setting the content to preferably 50% by mass or less, a suitable continuous coating structure of the polyurethane precursor is maintained, preventing deterioration of physical properties. Furthermore, the stability of the hydrophilic polyurethane liquid can be maintained.

[0151] In the method for producing an artificial leather of the present invention, it is also preferable to add 1% by mass or more and 10% by mass or less of a crosslinking agent to the polyurethane liquid having hydrophilic groups. By setting the concentration of the crosslinking agent in the polyurethane liquid having hydrophilic groups to 1% by mass or more, preferably 2% by mass or more, the crosslinking agent can introduce a larger amount of a three-dimensional network structure into the polyurethane precursor, resulting in an artificial leather with excellent properties such as abrasion resistance. On the other hand, by setting the concentration to 10% by mass or less, preferably 7% by mass or less, excessive crosslinking agent can be prevented from inhibiting the solidification of the polyurethane precursor when it is formed, making it easier to prevent a decrease in physical properties such as abrasion resistance.

[0152] The crosslinking agent used in the method for producing an artificial leather of the present invention is preferably a carbodiimide crosslinking agent and / or a blocked isocyanate crosslinking agent. This allows a three-dimensional crosslinked structure to be imparted to the molecules of the polymeric elastomer in the artificial leather via N-acylurea bonds and / or isourea bonds, which have excellent physical properties such as light resistance, heat resistance, and abrasion resistance, as well as flexibility, and allows the artificial leather to maintain its flexibility while dramatically improving its physical properties such as durability and abrasion resistance.

[0153] <Step for obtaining ultrafine fiber sheet> In this step, ultrafine fibers having an average single fiber diameter of 1.0 μm or more and 10.0 μm or less are produced from the ultrafine fiber-producing fibers of the polymeric elastomer-attached sheet, to obtain an ultrafine fiber sheet.

[0154] When islands-in-sea type composite fibers are used as the ultrafine fiber-producing fibers, the ultrafine fiber treatment (sea component removal treatment) can be carried out, for example, by immersing the islands-in-sea type composite fibers in a solvent and then subjecting them to a heat treatment. The solvent for dissolving the sea component can be appropriately selected depending on the type of sea component, and when the sea component is a copolymer polyester, an alkaline aqueous solution such as sodium hydroxide can be used.

[0155] When an aqueous alkaline solution is used as a solvent for the sea-removal treatment, the molar concentration of the aqueous alkaline solution is preferably 3 mol / L or less in order to prevent excessive deterioration of the polyurethane having hydrophilic groups.

[0156] During this sea component removal process, the silicone and non-silicone textile oil solids adhering to the fiber substrate are usually removed together with the sea component.

[0157] <Process for obtaining heat-treated sheet> In this step, the ultrafine fiber sheet is heat-treated at an ambient temperature of 150°C to 200°C for 5 to 20 minutes to obtain a heat-treated sheet. By setting the ambient temperature to 150°C or higher, preferably 155°C or higher, the adhesion between the ultrafine fibers and the polyurethane having hydrophilic groups is improved, which not only improves the abrasion resistance of the artificial leather but also reduces the molecular weight of a portion of the polyurethane having hydrophilic groups, thereby increasing the flexibility of the artificial leather. On the other hand, by setting the ambient temperature to 200°C or lower, preferably 190°C or lower, and more preferably 180°C or lower, the molecular weight of a portion of the polyurethane having hydrophilic groups can be gradually reduced.

[0158] Next, it is important that the heating time be 5 to 20 minutes. By setting the heating time to 5 minutes or more, preferably 6 minutes or more, the adhesion between the ultrafine fibers and the polyurethane having hydrophilic groups is improved, thereby improving the abrasion resistance of the artificial leather. Furthermore, in the step of forming the second surface described below, improved abrasion resistance prevents fiber shedding, allowing the raising treatment to be performed without damaging the woven fabric. On the other hand, by setting the heating time to 20 minutes or less, preferably 15 minutes or less, and more preferably 12 minutes or less, it is possible to prevent a deterioration in the physical properties of the artificial leather due to excessive reduction in the molecular weight of the polyurethane having hydrophilic groups.

[0159] This heat treatment is carried out after the ultrafine fiber sheet is obtained, but it is preferable to carry out the heat treatment immediately after the ultrafine fiber forming treatment in order to prevent deterioration of quality due to elongation during the process.

[0160] As a method for the heat treatment, it is preferable to use a hot air dryer such as a floater dryer, a drum dryer, or a pin tenter.

[0161] <Step of forming the first and second surfaces> In this process, the surface of the heat treatment sheet away from the fabric is ground to form a first surface having nap, and the surface opposite the first surface is ground or rubbed to form a second surface having nap.

[0162] The method for forming the nap is not particularly limited, and various methods commonly used in the art, such as buffing with sandpaper, can be used.

[0163] When the sheet is to be napped, a lubricant such as a silicone emulsion can be applied to the surface of the sheet before the nap-raising process. Furthermore, applying an antistatic agent before the nap-raising process makes it difficult for grinding dust generated from the sheet during grinding to accumulate on the sandpaper.

[0164] When buffing with sandpaper is used, the grit size of the sandpaper is preferably in the range of 120 (P120) or more and 600 (P600) or less as specified in JIS R6010:2000 "Grain size of abrasives for coated abrasives." By setting the paper grit size to 600 or less, preferably 400 or less, the nap length can be set within the above range. Furthermore, by setting the paper grit size to 120 or more, preferably 150 or more, a more uniform nap length can be achieved.

[0165] Furthermore, when woven fabrics are laminated on both sides of the nonwoven fabric and entangled and integrated, the nonwoven fabric can be cut in half in the thickness direction before this step to form the product of the present invention.

[0166] <Finishing process> In the method for producing the artificial leather of the present invention, the product that has undergone the above steps may be used as is as the artificial leather, but it is preferable to carry out various finishing steps as in the case of general artificial leathers. Of course, it goes without saying that artificial leather that has undergone post-processing is also treated as the artificial leather of the present invention.

[0167] First, the method for producing an artificial leather of the present invention preferably includes a dyeing step. This dyeing process can be performed using any of the methods commonly used in the art, including, for example, jet dyeing using a jigger dyeing machine or jet dyeing machine, dip dyeing such as thermosol dyeing using a continuous dyeing machine, or printing on the napped surface using roller printing, screen printing, inkjet printing, sublimation printing, vacuum sublimation printing, etc. Among these, jet dyeing machines are preferred because they can soften the artificial leather by providing a kneading effect simultaneously with dyeing. Furthermore, various resin finishing processes can be performed after dyeing, if necessary.

[0168] In addition, finishing treatment using a softener such as silicone, an antistatic agent, a water repellent, a flame retardant, a lightfastness agent, an antibacterial agent, etc. can be carried out in the same bath as dyeing or after dyeing.

[0169] Furthermore, in the method for producing an artificial leather of the present invention, the artificial leather can be subjected to post-processing such as perforation, embossing, laser processing, pinsonic processing, and printing, as needed. [Example]

[0170] Next, the artificial leather of the present invention will be described in more detail using examples, but the present invention is not limited to these examples.

[0171] [Evaluation method] The evaluation methods and measurement conditions used in the examples are explained below. Unless otherwise specified, the measurements of each physical property were carried out according to the above-mentioned methods.

[0172] (1) Number-average molecular weight of polyalkylene glycol The number average molecular weight of the polyalkylene glycol was measured and calculated by the above-mentioned method using a gel permeation chromatography (GPC) apparatus "HLC-8220" manufactured by Tosoh Corporation.

[0173] (2) Average single fiber diameter (μm): The average single fiber diameter (μm) was measured and calculated by the above-mentioned method using a scanning electron microscope (SEM) "VHX-D500 / D510" manufactured by Keyence Corporation.

[0174] (3) Artificial leather nap length (μm): The nap length of the artificial leather was measured using a scanning electron microscope, "VHX-D500 / D510" manufactured by Keyence Corporation.

[0175] (4) Artificial leather nap coverage (%): The nap coverage of the artificial leather was measured using a scanning electron microscope, "VHX-D500 / D510" manufactured by Keyence Corporation, and image analysis software, "ImageJ."

[0176] (5) Content of polyurethane having hydrophilic groups (mass%): The content (mass %) of polyurethane having a hydrophilic group was measured and calculated by the above-mentioned method.

[0177] (6) Fabric density (count / 2.54cm): The weave density of the woven fabric was evaluated by observing a cross section perpendicular to the thickness direction of the artificial leather at 50x magnification using a scanning electron microscope, Keyence Corporation's "VHX-D500 / D510," and counting the number of cross sections of the threads per 2.54 cm length.

[0178] (7) Apparent density of artificial leather The apparent density of the artificial leather was calculated by randomly taking three samples measuring 50 cm lengthwise and 50 cm widthwise from the artificial leather and dividing the thickness by the basis weight. The thickness was measured at five equally spaced points across the width of the sheet at each of the three sample locations using a thickness gauge with a 0.01 mm scale (disk diameter of 9 mm or more) under a load of 10 kPa, and the average value was calculated. The basis weight was calculated by measuring the mass of each sample at each of the three sample locations and converting the average of the obtained values ​​into a value per unit area.

[0179] (8) Weight loss from abrasion of artificial leather (mg): When measuring and calculating the abrasion weight loss (mg) of the artificial leather, a Martindale abrasion tester "Model 406" manufactured by James H. Heal & Co. was used, and the standard abrasion cloth was "ABRASTIVE CLOTH SM25" manufactured by the same company. A load of 12 kPa was applied to the artificial leather, and the abrasion count was set at 50,000 times. The abrasion weight loss was calculated using the mass of the artificial leather before and after abrasion using the following formula: Abrasion loss (mg) = mass before abrasion (mg) - mass after abrasion (mg) (formula) The abrasion loss (mg) was calculated by rounding off the value to the first decimal place.

[0180] (9) Breathability The breathability of artificial leather is measured by randomly taking five 200mm x 200mm test pieces from the artificial leather using TEXTEST's FX 3300-III according to JIS L1096:2020, 8.26 Breathability, 8.26.1 A Method (Fragile Method), and calculating the amount of air passing through the test piece (cm ) using the conversion table attached to the tester. 3 / cm 2 The average of the five calculated values ​​was used as the air permeability (cm 3 / cm 2 ·s).

[0181] (10) Surface quality of artificial leather: Twenty healthy adults were asked to visually judge the following evaluations, and the most common evaluation was taken as the surface quality of the artificial leather. In the case of a tie, the higher evaluation was taken as the surface quality of the artificial leather. In the present invention, a good level was taken as "A or B." A: The nap is uniform, and the exposed polymer elastomer is barely visible even when viewed with the naked eye, demonstrating very good surface quality. B: The nap is generally uniform, and the exposed polymeric elastomer cannot be seen with the naked eye without looking closely, and the surface quality is good. C: The nap is uneven, the exposed polymeric elastomer is visible to the naked eye, and the surface quality is poor. D: The nap is very uneven, and the exposed polymeric elastomer is easily visible to the naked eye, indicating very poor surface quality.

[0182] [Oil agent applied to raw cotton] Oil A: An oil containing 9% by mass of silicone solids and 6% by mass of solids derived from non-silicone textile oils Oil B: An oil containing 6% by mass of silicone solids and 6% by mass of solids derived from non-silicone textile oils Oil C: An oil containing 3% by mass of silicone solids and 6% by mass of solids derived from non-silicone textile oils Oil D: Oil containing 3% by mass of solids derived from non-silicone textile oil Oil E: Oil containing 15% by mass of silicone as solid content

[0183] [Sea component of raw cotton] Copolymerized PET-A: Copolymerized polyethylene terephthalate copolymerized with 8 mol% of sodium 5-sulfoisophthalate (polyethylene glycol is not copolymerized) Copolymerized PET-B: Copolymerized polyethylene terephthalate copolymerized with 6 mol% of sodium 5-sulfoisophthalate and 9.0 mass% of polyethylene glycol having a number average molecular weight of 2000

[0184] [Example 1] <Step of obtaining fibrous base material> Copolymerized PET-A was used as the sea component and polyethylene terephthalate with an intrinsic viscosity of 0.73 was used as the island component. Using an islands-in-sea composite spinneret with an island number of 16 per hole, melt spinning was performed under the following conditions: spinning temperature: 285°C, islands / sea mass ratio: 80 / 20, throughput: 1.6 g / min per hole, and spinning speed: 1100 m / min. The fibers were then stretched 3.8 times in an oil bath, after which oil A was applied in an amount of 0.63 mass% relative to the islands-in-sea composite fiber. The fibers were cut to a length of 51 mm to obtain raw fibers for islands-in-sea composite fibers with a single fiber fineness of 3.8 dtex. The raw fibers for the islands-in-sea composite fibers were then passed through carding and cross-wrapping processes to obtain an apparent density of 0.09 g / cm. 3 After forming the laminated web, a plain woven fabric having a warp density of 95 threads / 2.54 cm and a weft density of 76 threads / 2.54 cm was laminated on both sides of the laminated web, and the weft density was 3500 threads / cm. The plain woven fabric used for both the weft and the warp was a multifilament consisting of 72 filaments made of polyethylene terephthalate with an average single fiber diameter of 11 μm and twisted at 2500 T / m. 2 The fabric weight is 765g / m2, which is obtained by needle punching at a punch density of 2 The thickness is 3.0 mm, the width is 165 cm, and the apparent density is 0.25 g / cm 3 A fibrous substrate consisting of a nonwoven fabric made of sea-island composite fibers and a woven fabric was obtained.

[0185] <Step of obtaining a sheet with polymeric elastomer> A hydrophilic polyurethane solution was prepared containing 12 parts by weight of a polyurethane precursor consisting of polytetramethylene glycol as a polymer polyol, MDI as an organic diisocyanate, 2,2-dimethylolpropionic acid as an active hydrogen-containing compound having a hydrophilic group, and ethylene glycol as a chain extender, 1 part by weight of a carbodiimide crosslinking agent, 5 parts by weight of sodium sulfate, and 82 parts by weight of water. The fibrous substrate was impregnated with the hydrophilic polyurethane solution, squeezed with a mangle, and heated with hot air at 120°C for 20 minutes to solidify the polyurethane precursor, thereby solidifying the polyurethane, and a polymeric elastomer-attached sheet was obtained, which was composed of polyurethane having a crosslinked structure formed by N-acylurea bonds and / or isourea bonds.

[0186] <Step for obtaining ultrafine fiber sheet> The sheet with polymeric elastomer was immersed in a 5% aqueous sodium hydroxide solution, squeezed with a mangle, and heat-treated with steam at 95°C for 10 minutes to alkaline decompose the sea component of the islands-in-sea type composite fiber. Next, the excess sodium hydroxide was washed away with water to obtain an ultrafine fiber sheet composed of ultrafine fibers, a woven fabric, and polyurethane having hydrophilic groups, the ultrafine fibers having an average single fiber diameter of 4.4 µm.

[0187] <Process for obtaining heat-treated sheet> The ultrafine fiber sheet was heat-treated for 10 minutes in a pin tenter with the atmosphere temperature raised to 160°C, to obtain a heat-treated sheet composed of ultrafine fibers, woven fabric, and polyurethane having hydrophilic groups.

[0188] <Step of forming the first surface> The obtained sheet was cut in half perpendicular to the thickness direction, and the surface farther from the woven fabric was ground with endless sandpaper of sandpaper size 240 to form a first surface.

[0189] <Step of forming the second surface> The first surface and the other surface of the sheet were abraded with endless sandpaper of grit size 320 to form a second surface.

[0190] <Finishing process> The sheet was dyed with a disperse dye at 120°C using a jet dyeing machine. It was then dried in a dryer to obtain artificial leather. The results are shown in Table 1. The obtained artificial leather had a dense and elegant surface quality on both surfaces and was excellent in breathability and abrasion resistance.

[0191] [Example 2] Artificial leather was obtained in the same manner as in Example 1, except that in the <step of obtaining a fibrous substrate>, oil agent A was changed to oil agent B, and oil agent B was applied in an amount of 0.79% by mass relative to the raw cotton. The results are shown in Table 1. The obtained artificial leather had a dense and elegant surface quality on both surfaces and was excellent in breathability and abrasion resistance.

[0192] [Example 3] An artificial leather was obtained in the same manner as in Example 1, except that in the <step of obtaining a fibrous base material>, oil agent A was changed to oil agent C, and oil agent C was applied in an amount of 0.42 mass % relative to the raw cotton. The results are shown in Table 1. The obtained artificial leather had a dense and elegant surface quality on both surfaces and was excellent in breathability and abrasion resistance.

[0193] [Example 4] An artificial leather was obtained in the same manner as in Example 1, except that in the <step of obtaining a fibrous base material>, the average single fiber diameter of the ultrafine fibers was set to 1.9 μm and oil agent A was applied in an amount of 0.60 mass % relative to the raw cotton. The results are shown in Table 1. The obtained artificial leather had a dense and elegant surface quality on both surfaces and was excellent in breathability and abrasion resistance.

[0194] [Example 5] An artificial leather was obtained in the same manner as in Example 1, except that in the <step of obtaining a fibrous base material>, the average single fiber diameter of the ultrafine fibers was 7.8 μm and oil agent A was applied in an amount of 0.57 mass % relative to the raw cotton. The results are shown in Table 1. The obtained artificial leather had a dense and elegant surface quality on both surfaces.

[0195] [Example 6] An artificial leather was obtained in the same manner as in Example 1, except that in the <step of obtaining a fibrous substrate>, copolymerized PET-A was changed to copolymerized PET-B and oil agent A was applied in an amount of 0.64 mass % relative to the raw cotton. The results are shown in Table 1. The obtained artificial leather had a dense and elegant surface quality on both surfaces.

[0196] [Comparative Example 1] An artificial leather was obtained in the same manner as in Example 1, except that in the <step of obtaining a fibrous base material>, oil agent A was changed to oil agent D, and 0.35% by mass of oil agent D was applied to the raw cotton. The results are shown in Table 2. The obtained artificial leather had a second surface that was inferior in density to the artificial leather of Example 1.

[0197] Comparative Example 2 An artificial leather was obtained in the same manner as in Example 1, except that in the <step of obtaining a fibrous substrate>, oil agent D and oil agent E were applied separately to the part where oil agent A was applied to the raw cotton, and a total of 0.56 mass% of the raw cotton was applied. The results are shown in Table 2. The obtained artificial leather had a second surface that was inferior in density to the artificial leather of Example 1.

[0198] Comparative Example 3 An artificial leather was obtained in the same manner as in Example 1, except that the <step of obtaining a heat-treated sheet> was not performed, the steps from the <step of forming a first surface> onwards were performed, and oil agent A was applied in an amount of 0.63 mass % relative to the raw cotton. The results are shown in Table 2. The obtained artificial leather had a slightly inferior first surface density and was significantly inferior in the second surface density and abrasion resistance compared to the artificial leather of Example 1.

[0199] Comparative Example 4 An artificial leather was obtained in the same manner as in Example 1, except that in the <step of obtaining a fibrous base material>, polystyrene was used for the sea component of the islands-in-sea type composite fiber, a solvent-based polyurethane was used as the polymer elastomer, and oil agent A was changed to oil agent E, which was applied in an amount of 0.44 mass % based on the raw cotton. The results are shown in Table 2. The obtained artificial leather was significantly inferior to the artificial leather of Example 1 in the denseness and abrasion resistance of the second surface.

[0200] [Table 1]

[0201] [Table 2] [Explanation of symbols]

[0202] 10 Artificial leather 11 First Surface 12 Layer consisting of ultrafine fibers and polymeric elastomer 13 Layer consisting of ultrafine fibers, fabric, and polymeric elastomer 14 Second Surface

Claims

1. An artificial leather comprising a fibrous base material and a polymeric elastomer, The fibrous base material comprises a nonwoven fabric made of ultrafine fibers having an average single fiber diameter of 1.0 μm or more and 10.0 μm or less, and a woven fabric, and when the surface of the artificial leather farther from the woven fabric is defined as a first surface and the surface opposite to the first surface is defined as a second surface, the first surface and the second surface satisfy the following requirements 1 to 3. Requirement 1: Both the first surface and the second surface have nap. Requirement 2: On the first surface, the average value of the nap length is 200 μm or more and 500 μm or less, and the coefficient of variation of the nap length is 30% or less. Requirement 3: On the second surface, the nap coverage is 97.5% or more, the average nap length is 500 μm or more and 1000 μm or less, and the coefficient of variation of the nap length is 30% or less.

2. 2. The artificial leather according to claim 1, wherein the polymeric elastomer is a polyurethane having a hydrophilic group, and the polyurethane is a polyether polyurethane and / or a polycarbonate polyurethane.

3. 3. The artificial leather according to claim 1, wherein the content of the polymeric elastomer in the artificial leather is 15% by mass or more and 25% by mass or less.

4. 3. The artificial leather according to claim 1, wherein the woven fabric has a fiber weave density of 70 threads / 2.54 cm or more and 120 threads / 2.54 cm or less.

5. The apparent density of the artificial leather is 0.20 g / cm ３ 0.40g / cm or more ３ The artificial leather according to claim 1 or 2, wherein:

6. Clothing comprising the artificial leather according to claim 1 or 2.

7. A bag comprising the artificial leather according to claim 1 or 2.

8. a step of obtaining a nonwoven fabric comprising ultrafine fiber-developing fibers, the ultrafine fiber-developing fibers being islands-in-sea composite fibers in which the sea component is an alkali-soluble resin and to which solids derived from a mixed oil solution of silicone and non-silicone fiber oil solution are adhered, the amount of the adhered solids being 0.30% by mass or more and 1.00% by mass or less; a step of entangling and integrating the nonwoven fabric and the woven fabric to obtain a fibrous substrate; a step of providing a polymeric elastomer to the fibrous base material to obtain a polymeric elastomer-coated sheet; a step of treating the polymeric elastomer-attached sheet with an alkali to express ultrafine fibers having an average single fiber diameter of 1.0 μm or more and 10.0 μm or less from the ultrafine fiber-expressing fibers, thereby obtaining an ultrafine fiber sheet; a step of heat-treating the ultrafine fiber sheet at an atmospheric temperature of 150°C or higher and 200°C or lower for 5 minutes or longer and 20 minutes or shorter to obtain a heat-treated sheet; grinding a surface of the heat treatment sheet away from the woven fabric to form a first surface having nap; grinding or scraping the other surface to form a second surface having nap; A method for producing artificial leather, comprising: On the first surface, an average value of the nap length is 200 μm or more and 500 μm or less, and a coefficient of variation of the nap length is 30% or less, On the second surface, the nap coverage is 97.5% or more, the average nap length is 500 μm or more and 1000 μm or less, and the variation coefficient of the nap length is 30% or less. A method for manufacturing artificial leather.

9. The method for producing an artificial leather according to claim 8, wherein the proportion of silicone in the solid content derived from the mixed oil agent is 30% by mass or more and 70% by mass or less.

10. 10. The method for producing an artificial leather according to claim 8, wherein the alkali-soluble resin is a copolymer polyester copolymerized with a polyalkylene glycol having a number average molecular weight of 500 to 3,500.

11. The method for producing an artificial leather according to claim 8 or 9, wherein the entanglement and integration are carried out by needle punching in the step of obtaining the fibrous base material.

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