WO2024095846A1 - Artificial leather and method for manufacturing same - Google Patents

Artificial leather and method for manufacturing same Download PDF

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Publication number
WO2024095846A1
WO2024095846A1 PCT/JP2023/038438 JP2023038438W WO2024095846A1 WO 2024095846 A1 WO2024095846 A1 WO 2024095846A1 JP 2023038438 W JP2023038438 W JP 2023038438W WO 2024095846 A1 WO2024095846 A1 WO 2024095846A1
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artificial leather
polyurethane
mass
less
hydrophilic group
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PCT/JP2023/038438
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French (fr)
Japanese (ja)
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駿一 木村
誠 山科
智 柳澤
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東レ株式会社
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    • D—TEXTILES; PAPER
    • D06—TREATMENT OF TEXTILES OR THE LIKE; LAUNDERING; FLEXIBLE MATERIALS NOT OTHERWISE PROVIDED FOR
    • D06N—WALL, FLOOR, OR LIKE COVERING MATERIALS, e.g. LINOLEUM, OILCLOTH, ARTIFICIAL LEATHER, ROOFING FELT, CONSISTING OF A FIBROUS WEB COATED WITH A LAYER OF MACROMOLECULAR MATERIAL; FLEXIBLE SHEET MATERIAL NOT OTHERWISE PROVIDED FOR
    • D06N3/00—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof
    • D06N3/12—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins
    • D06N3/14—Artificial leather, oilcloth or other material obtained by covering fibrous webs with macromolecular material, e.g. resins, rubber or derivatives thereof with macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds, e.g. gelatine proteins with polyurethanes

Definitions

  • the present invention relates to artificial leather and a method for producing the same.
  • Artificial leather which is mainly made of a fibrous base material such as nonwoven fabric and polyurethane, has excellent characteristics that natural leather does not have, and its use is expanding year by year in applications such as clothing, furniture, and vehicle interior materials.
  • a more environmentally friendly method of using water-dispersed polyurethane, in which polyurethane resin is dispersed in water is being considered as an alternative to the conventional method of using organic solvent-based polyurethane.
  • Patent Document 1 proposes a method in which a specific amount of polyvinyl alcohol with a specific degree of saponification and a specific degree of polymerization is applied to a fibrous substrate, then a water-dispersible polyurethane is applied, and then the polyvinyl alcohol is removed. It is described that this method achieves an elegant appearance and soft feel, and also makes it possible to obtain a sheet-like material with good abrasion resistance.
  • Patent Document 2 also proposes a method including, in this order, a polymer elastomer impregnation step in which a fibrous substrate made of ultrafine fiber-producing fibers is impregnated with an aqueous dispersion containing a specific polymer elastomer, a specific amount of inorganic salt containing monovalent cations, and a crosslinking agent, and then a heat treatment is performed at a specific temperature, a microfiber producing step, a drying step, and a nap raising step. It is described that this method produces a sheet-like material that combines a soft texture with excellent light resistance.
  • Patent Document 3 proposes a method of impregnating and fixing an aqueous emulsion of polyurethane before and after removing the sea component from islands-in-the-sea composite fibers. It also describes that this method makes it possible to produce a suede-type ultrafine fiber nonwoven fabric with optimal physical and mechanical properties, abrasion resistance, and appearance.
  • Patent Document 4 proposes a method for carrying out a polymer elastomer impregnation step in which a fibrous substrate made of ultrafine fiber-producing fibers is impregnated with an aqueous dispersion containing a specific polymer elastomer, a specific amount of an inorganic salt containing a monovalent cation, and a crosslinking agent before and after the ultrafine fiber producing step, and then a heat treatment is carried out at a specific temperature. It is described that this method produces a sheet-like material with excellent flexibility, chemical resistance, and dye resistance.
  • Patent Document 2 also moderates the adhesion between the polyurethane and the ultrafine fibers, achieving a soft texture without adding polyvinyl alcohol. However, there is room for improvement in terms of durability, including abrasion resistance.
  • the object of the present invention is to provide an artificial leather and a manufacturing method thereof that combines a soft feel with excellent durability while being produced using an environmentally friendly process that does not use organic solvents.
  • An artificial leather comprising, as components, a fibrous base material composed of polyester ultrafine fibers having an average single fiber diameter of 0.1 ⁇ m or more and 10.0 ⁇ m or less, and a polyurethane having a hydrophilic group, wherein the content of the polyurethane having a hydrophilic group in the artificial leather is 15% by mass or more and 25% by mass or less, the mass retention rate of the polyurethane having a hydrophilic group after the artificial leather is immersed in N,N-dimethylformamide at 25° C.
  • the present invention makes it possible to obtain artificial leather that combines a soft feel with excellent abrasion resistance.
  • FIG. 1 is a schematic cross-sectional view illustrating a method for measuring the average nap length of the artificial leather of the present invention.
  • the artificial leather of the present invention is an artificial leather containing as its components a fibrous base material composed of polyester ultrafine fibers having an average single fiber diameter of 0.1 ⁇ m or more and 10.0 ⁇ m or less, and a polyurethane having a hydrophilic group, the content of the polyurethane having a hydrophilic group in the artificial leather is 15% by mass or more and 25% by mass or less, the mass retention rate of the polyurethane having a hydrophilic group after the artificial leather is immersed in N,N-dimethylformamide at 25°C for 24 hours is 50% by mass or more and 80% by mass or less, and the weight average molecular weight of the component dissolved in N,N-dimethylformamide after the artificial leather is immersed in N,N-dimethylformamide at 25°C for 24 hours is 50,000 or more and 100,000 or less.
  • the artificial leather of the present invention is made of a fibrous base material, which is one of the components, composed of polyester ultrafine fibers having an average single fiber diameter of 0.1 ⁇ m or more and 10.0 ⁇ m or less.
  • polyester ultrafine fibers refers to ultrafine fibers made of a polyester resin described below, and ultrafine fibers refer to "fibers having a single fiber diameter of 0.1 ⁇ m or more and 10.0 ⁇ m or less" measured and calculated by the method described below.
  • polyester-based resin refers to a resin in which the molar fraction of polyester units in the repeating units is 80 mol% to 100 mol%. Unless otherwise specified, the term “...-based resin” has the same meaning.
  • This polyester-based resin can be used to make artificial leather with excellent heat resistance, light resistance, etc., and specific examples include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and mixtures and copolymers of these polyester resins. Polyester-based resins can be obtained, for example, from dicarboxylic acids and/or their ester-forming derivatives and diols as raw materials.
  • the dicarboxylic acid and/or its ester-forming derivative used in the polyester resin may include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4'-dicarboxylic acid and its ester-forming derivative.
  • the ester-forming derivative in the present invention is a lower alkyl ester of a dicarboxylic acid, an acid anhydride, an acyl chloride, etc. Specifically, methyl ester, ethyl ester, hydroxyethyl ester, etc. are preferably used.
  • a more preferred embodiment of the dicarboxylic acid and/or its ester-forming derivative used in the present invention is terephthalic acid and/or its dimethyl ester.
  • Diols used in the polyester resins include ethylene glycol, 1,3-propanediol, 1,4-butanediol, cyclohexanedimethanol, etc. Among these, ethylene glycol is preferably used.
  • the polyester resin can contain inorganic particles such as titanium oxide particles, lubricants, pigments, heat stabilizers, UV absorbers, conductive agents, heat storage agents, antibacterial agents, etc., depending on the purpose.
  • the content of components other than polyester resin that can be contained in polyester resin is preferably 3% by mass or less, more preferably 1.5% by mass or less.
  • the cross-sectional shape of polyester microfibers can be either round or irregular.
  • irregular cross-sections include ellipses, flats, polygons such as triangles, sectors, and crosses.
  • the average single fiber diameter of the polyester ultrafine fibers is 0.1 ⁇ m or more and 10.0 ⁇ m or less.
  • the artificial leather can be made more flexible.
  • the quality of the nap can be improved.
  • the artificial leather can have excellent color development after dyeing when dyeing.
  • the ease of dispersion and handling of the polyester ultrafine fibers present in bundles can be improved.
  • the single fiber diameter and average single fiber diameter of the polyester ultrafine fiber in the present invention are measured and calculated by the following method.
  • the cross section of the obtained artificial leather cut in the thickness direction is observed under a scanning electron microscope (SEM, for example, "VHX-D500/D510" manufactured by Keyence Corporation) at a magnification of 1000 times.
  • SEM scanning electron microscope
  • the single fiber diameters of 50 random polyester ultrafine fibers within the observation area are measured in three directions on the cross section of each polyester ultrafine fiber.
  • the cross-sectional area of the single fiber is first measured, and the diameter of the circle with the cross-sectional area is calculated using the following formula.
  • the diameter thus obtained is regarded as the single fiber diameter of the single fiber:
  • Single fiber diameter ( ⁇ m) (4 ⁇ (cross-sectional area of single fiber ( ⁇ m2 )) / ⁇ ) 1/2 (3)
  • the arithmetic mean value ( ⁇ m) of the single fiber diameters of the total of 150 points obtained as described above is calculated, and rounded off to one decimal place to obtain the average single fiber diameter ( ⁇ m) of the polyester ultrafine fiber.
  • the fibrous base material used in the present invention is composed of the above-mentioned polyester ultrafine fibers. It is acceptable for the fibrous base material to contain polyester ultrafine fibers made of different raw materials.
  • the fibrous substrate include nonwoven fabrics in which the polyester ultrafine fibers are entangled with each other and nonwoven fabrics in which fiber bundles of polyester ultrafine fibers are entangled.
  • nonwoven fabrics in which fiber bundles of polyester ultrafine fibers are entangled are preferably used from the viewpoint of the strength and texture of the artificial leather.
  • nonwoven fabrics in which the polyester ultrafine fibers constituting the fiber bundles of polyester ultrafine fibers are appropriately spaced apart and have gaps of 1 ⁇ m to 100 ⁇ m are particularly preferably used.
  • nonwoven fabrics in which fiber bundles of polyester ultrafine fibers are entangled with each other can be obtained, for example, by entangling ultrafine fiber-expressing fibers in advance and then expressing polyester ultrafine fibers.
  • nonwoven fabrics in which the polyester ultrafine fibers constituting the fiber bundles of polyester ultrafine fibers are appropriately spaced apart and have gaps can be obtained, for example, by using sea-island composite fibers in which gaps can be formed between island components by removing the sea component.
  • the nonwoven fabric may be either a short fiber nonwoven fabric or a long fiber nonwoven fabric, but from the viewpoint of the texture and quality of the artificial leather, a short fiber nonwoven fabric is more preferably used.
  • a short fiber nonwoven fabric refers to a nonwoven fabric composed exclusively of fibers with a fiber length of less than 1000 mm.
  • the fiber length of the fibers that make up the short-fiber nonwoven fabric is preferably in the range of 25 mm or more and 90 mm or less.
  • the fiber length 25 mm or more more preferably 35 mm or more, and even more preferably 40 mm or more, it becomes easier to obtain artificial leather with excellent abrasion resistance due to entanglement.
  • the fiber length 90 mm or less more preferably 80 mm or less, and even more preferably 70 mm or less, it becomes possible to obtain artificial leather with better texture and quality.
  • a woven or knitted fabric when a nonwoven fabric is used as the fibrous substrate, a woven or knitted fabric can be inserted, laminated, or lined inside the nonwoven fabric for the purpose of improving strength.
  • the average single fiber diameter of the fibers constituting such a woven or knitted fabric is preferably 0.3 ⁇ m or more and 10 ⁇ m or less, since this can suppress damage during entanglement and maintain strength.
  • the total fineness of the multifilaments is preferably 30 dtex or more and 170 dtex or less.
  • the total fineness of the multifilaments constituting the woven fabric etc. 170 dtex or less more preferably 150 dtex or less, an artificial leather with excellent flexibility can be obtained.
  • the total fineness 30 dtex or more not only does the shape stability of the product as artificial leather improve, but also when the nonwoven fabric and the woven fabric etc. are entangled and integrated by needle punching or the like, the fibers constituting the woven fabric etc. are less likely to be exposed on the surface of the artificial leather, which is preferable.
  • the total fineness of the multifilaments of the warp threads and weft threads in the woven fabric may be the same or different.
  • the total fineness of the multifilament refers to the value measured and calculated according to "8.3 Fineness” of "8.3.1 Correct fineness b) Method B (simplified method)" in “8.3 Fineness” of JIS L1013:2010 “Test methods for chemical fiber filament yarns.”
  • the fibers constituting the woven or knitted fabrics may be synthetic fibers such as polyesters, such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polylactic acid, polyamides, such as polyamide 6 and polyamide 66, regenerated fibers, such as cellulose-based polymers, and natural fibers, such as cotton and hemp.
  • synthetic fibers such as polyesters, such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polylactic acid, polyamides, such as polyamide 6 and polyamide 66, regenerated fibers, such as cellulose-based polymers, and natural fibers, such as cotton and hemp.
  • the apparent density of the fibrous substrate is preferably 0.25 g/cm 3 or more and 0.30 g/cm 3 or less.
  • the lower limit of the apparent density range of the fibrous substrate is 0.25 g/cm 3 or more, more preferably 0.26 g/cm 3 or more.
  • the upper limit of the above range is 0.30 g/cm 3 or less, more preferably 0.28 g/cm 3 or less, the polyurethane having a hydrophilic group is uniformly applied, and the artificial leather has excellent resilience.
  • the apparent density of the fibrous substrate is calculated by the following formula.
  • the fibrous base material ratio (%) in the artificial leather refers to the percentage of mass reduced by extraction when only the polyester ultrafine fibers of the artificial leather are extracted with a solvent, with the mass of the artificial leather being taken as 100%.
  • the artificial leather of the present invention contains polyurethane having a hydrophilic group as a constituent element. The details of this will be described in further detail below.
  • the "hydrophilic group” refers to a "group having active hydrogen".
  • the group having active hydrogen include a hydroxyl group, a carboxyl group, a sulfonic acid group, and an amino group. From the viewpoint of reactivity with a crosslinking agent having a carbodiimide group described later, a hydroxyl group or a carboxyl group is preferred.
  • Polyurethanes having hydrophilic groups can be obtained by reacting a polymer polyol (described below), an organic diisocyanate, and an active hydrogen component-containing compound having a hydrophilic group to form a hydrophilic prepolymer, and then adding and reacting a chain extender to obtain a polyurethane precursor, and then reacting the polyurethane precursor with a crosslinking agent. These are explained in detail below.
  • Polymer polyols preferably used in the present invention include polyether polyols, polyester polyols, polycarbonate polyols, and the like.
  • 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, as well as polyols obtained by ring-opening polymerization of the above-mentioned monomers using protonic acids, Lewis acids, cationic catalysts, and the like as catalysts.
  • Specific examples include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like, as well as copolymer polyols that combine these.
  • polyester polyols include polyester polyols obtained by condensing various low molecular weight polyols with polybasic acids, and polyols obtained by depolymerizing lactones.
  • Low molecular weight polyols used in polyester polyols include, for example, 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( ⁇ -hydroxyethoxy)benzene. Adducts obtained by
  • polyester polyols examples 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.
  • 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.
  • the polyol used in the polycarbonate-based polyol the low molecular weight polyol used in the polyester-based polyol can be used.
  • the dialkyl carbonate dimethyl carbonate, diethyl carbonate, etc.
  • the diaryl carbonate, diphenyl carbonate, etc. can be used.
  • the number average molecular weight of the polymer polyol preferably used in the present invention is preferably 500 or more and 5000 or less.
  • the number average molecular weight of the polymer polyol 500 or more more preferably 1500 or more, it is possible to easily prevent the texture of the artificial leather from becoming hard.
  • the number average molecular weight 5000 or less more preferably 4000 or less, it is possible to easily maintain the strength of the polyurethane having hydrophilic groups as a binder.
  • organic diisocyanate examples include aromatic diisocyanates having 6 to 20 carbon atoms (excluding carbons in NCO groups, the same applies below), 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, urethodione modified products, etc.), and mixtures of two or more of these.
  • aromatic diisocyanate having 6 to 20 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.
  • MDI 1,3- and/or 1,4-phenylene diisocyanate
  • 2,4- and/or 2,6-tolylene diisocyanate 2,4'- and/or 4,4'-diphenylmethane diisocyanate
  • MDI 4,4'-diisocyanatobiphenyl
  • aliphatic diisocyanates having 2 to 18 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.
  • alicyclic diisocyanates 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.
  • dicyclohexylmethane-4,4'-diisocyanate which has excellent durability when made into a polyurethane having a hydrophilic group.
  • aromatic aliphatic diisocyanates having 8 to 15 carbon atoms include m- and/or p-xylylene diisocyanate and ⁇ , ⁇ , ⁇ ', ⁇ '-tetramethylxylylene diisocyanate.
  • the active hydrogen component-containing compound having a hydrophilic group that is preferably used in the present invention includes compounds containing active hydrogen and one or more 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. By using this active hydrogen component-containing compound having a hydrophilic group, the stability of the aqueous dispersion used in the manufacturing method of the artificial leather described below can be improved.
  • Examples of compounds that have a nonionic group and active hydrogen include compounds that contain two or more active hydrogen components or two or more isocyanate groups and have polyoxyethylene glycol groups with a molecular weight of 250 to 9000 on the side chain, and triols such as trimethylolpropane and trimethylolbutane.
  • 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 their derivatives; sulfonic acid group-containing compounds such as 1,3-phenylenediamine-4,6-disulfonic acid and 3-(2,3-dihydroxypropoxy)-1-propanesulfonic acid, and their derivatives; and salts of these compounds neutralized with a neutralizing agent.
  • carboxyl group-containing compounds such as 2,2-dimethylolpropionic acid, 2,2-dimethylolbutanoic acid, and 2,2-dimethylolvaleric acid, and their derivatives
  • sulfonic acid group-containing compounds such as 1,3-phenylenediamine-4,6-disulfonic acid and 3-(2,3-dihydroxypropoxy)-1-propanesulfonic acid, and their derivatives
  • 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, as well as their derivatives.
  • chain extender examples 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 "xylylenediamine,” alkanolamines such as “ethanolamine,” hydrazine, dihydrazides such as “adipic acid dihydrazide,” and mixtures of two or more
  • preferred chain extenders are those selected from water, low molecular weight diols and aromatic diamines, and more preferably those selected from water, ethylene glycol, 1,4-butanediol, 4,4'-diaminodiphenylmethane and mixtures of two or more of these.
  • the polyurethane precursor used in the present invention is prepared by reacting the above-mentioned high molecular weight 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.
  • 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.
  • Specific examples include polyisocyanate-based crosslinking agents such as water-soluble isocyanate compounds and blocked isocyanate compounds, melamine-based crosslinking agents, and carbodiimide-based crosslinking agents.
  • the crosslinking agents may be used alone or in combination of two or more.
  • Water-soluble isocyanate compounds have two or more isocyanate groups in the molecule, and examples of such compounds include the organic diisocyanate compounds mentioned above.
  • Commercially available products include the "Bayhydur” (registered trademark) series and the “Desmodur” (registered trademark) series manufactured by Bayer MaterialScience Co., Ltd.
  • a blocked isocyanate compound has two or more blocked isocyanate groups in the molecule.
  • a blocked isocyanate group refers to an organic polyisocyanate compound that has been blocked with a blocking agent such as amines, phenols, imines, mercaptans, pyrazoles, oximes, or active methylenes.
  • a blocking agent such as amines, phenols, imines, mercaptans, pyrazoles, oximes, or active methylenes.
  • Commercially available products include the "Elastron” (registered trademark) series from Daiichi Kogyo Seiyaku Co., Ltd., the "Duranate” (registered trademark) series from Asahi Kasei Corporation, and the "Takenate” (registered trademark) series from Mitsui Chemicals, Inc.
  • Oxazoline-based crosslinking agents include compounds that have 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.
  • Carbodiimide crosslinking agents include compounds that have two or more carbodiimide groups in the molecule.
  • Commercially available products include the "Carbodilite” (registered trademark) series manufactured by Nisshinbo Chemical Inc.
  • the polyurethane having hydrophilic group preferably contains a constituent component derived from polyether-based polyol.
  • a constituent component derived from polyether-based polyol in the polyurethane having hydrophilic group the degree of freedom of the ether bond is high, so that the glass transition temperature is low and the cohesive force is weak, so that the water-dispersible polyurethane having excellent flexibility can be obtained.
  • the polyurethane having hydrophilic groups further contains a component derived from a polycarbonate-based polyol.
  • a component derived from a polycarbonate-based polyol in the polyurethane having hydrophilic groups it is possible to obtain a polyurethane having hydrophilic groups that has excellent water resistance, heat resistance, weather resistance, and mechanical properties due to the high cohesive force of the carbonate groups.
  • the method for confirming the components of polyurethane having hydrophilic groups is to dissolve the polyester ultrafine fibers that make up the artificial leather from the artificial leather and analyze the insoluble matter (polyurethane having hydrophilic groups) by infrared spectroscopy (analytical equipment such as the FT/IR 4000 series manufactured by JASCO Corporation) and pyrolysis GC/MS analysis (analytical equipment such as the GCMS-QP5050A manufactured by Shimadzu Corporation), thereby making it possible to confirm that the polyurethane having hydrophilic groups contains components derived from polyester polyol and components derived from polycarbonate polyol.
  • infrared spectroscopy analytical equipment such as the FT/IR 4000 series manufactured by JASCO Corporation
  • pyrolysis GC/MS analysis analytical equipment such as the GCMS-QP5050A manufactured by Shimadzu Corporation
  • m-cresol and hexafluoroisopropanol can be used, but it is preferable to use hexafluoroisopropanol, which can be handled at room temperature.
  • 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 increased.
  • N-acylurea groups and isourea groups in polyurethanes having hydrophilic groups can be analyzed by performing a mapping process such as time-of-flight secondary ion mass spectrometry (TOF-SIMS analysis) on a cross section of the artificial leather (analytical equipment such as the TOF.SIMS 5 manufactured by ION-TOF, Inc.) or infrared spectroscopy (analytical equipment such as the FT/IR 4000 series manufactured by JASCO Corporation).
  • TOF-SIMS analysis time-of-flight secondary ion mass spectrometry
  • TOF-SIMS 5 manufactured by ION-TOF, Inc.
  • infrared spectroscopy analytical equipment such as the FT/IR 4000 series manufactured by JASCO Corporation
  • the artificial leather of the present invention is an artificial leather containing the fibrous base material and the polyurethane having a hydrophilic group as components.
  • the content of the polyurethane having a hydrophilic group in the artificial leather is 15% by mass or more and 25% by mass or less
  • the mass retention of the polyurethane having a hydrophilic group after the artificial leather is immersed in N,N-dimethylformamide at 25° C. for 24 hours is 50% by mass or more and 80% by mass or less
  • the weight average molecular weight of the component dissolved in N,N-dimethylformamide after the artificial leather is immersed in N,N-dimethylformamide at 25° C. for 24 hours is 50,000 or more and 100,000 or less. Only by satisfying all of these three conditions can an artificial leather be obtained that has a soft texture and is less susceptible to changes in appearance such as breakage, holes, and pilling even when subjected to a highly loaded abrasion test.
  • the artificial leather of the present invention has a content of polyurethane having hydrophilic groups of 15% by mass or more and 25% by mass or less.
  • the content of polyurethane having hydrophilic groups 15% by mass or more, preferably 18% by mass or more, the artificial leather has excellent abrasion resistance.
  • the content 25% by mass or less preferably 22% by mass or less, the artificial leather has a soft feel.
  • the content of the polyurethane having a hydrophilic group is measured and calculated by the following method.
  • a test piece measuring 5 cm x 5 cm is cut out from the artificial leather, and the mass (M x ) of the test piece is measured.
  • the test piece is immersed in hexafluoroisopropanol to dissolve the polyester ultrafine fibers from the artificial leather.
  • the insoluble component (polyurethane having hydrophilic groups) of (2) is dried in a dryer at 100° C., the mass (M A ) is measured, and the content of polyurethane having hydrophilic groups in the artificial leather is calculated using the following formula.
  • Content (%) of polyurethane having hydrophilic group (M A /M X ) ⁇ 100.
  • the artificial leather of the present invention has a mass retention rate of the polyurethane having hydrophilic groups (hereinafter, sometimes simply abbreviated as "mass retention rate of polyurethane having hydrophilic groups") of 50% by mass or more and 80% by mass or less after the artificial leather is immersed in N,N-dimethylformamide at 25°C for 24 hours.
  • the mass retention rate of polyurethane having hydrophilic groups correlates with the durability and flexibility of polyurethane having hydrophilic groups.
  • the artificial leather When the lower limit is 50% by mass or more, preferably 55% by mass or more, and more preferably 60% by mass or more, the artificial leather has excellent durability, including abrasion resistance, due to the high molecular weight and durable components of the polyurethane having hydrophilic groups that are insoluble in N,N-dimethylformamide.
  • the upper limit of the mass retention rate of polyurethane having hydrophilic groups is 80% by mass or less, preferably 75% by mass or less, and more preferably 70% by mass or less
  • the artificial leather has a soft and excellent texture due to the low molecular weight and texture-excellent components of the polyurethane having hydrophilic groups that are soluble in N,N-dimethylformamide.
  • the mass retention of the hydrophilic group-containing polyurethane is measured and calculated by the following method.
  • a test piece measuring 5 cm x 5 cm is cut out from the artificial leather.
  • the test piece is immersed in hexafluoroisopropanol to dissolve the polyester ultrafine fibers from the artificial leather.
  • the insoluble component (polyurethane having hydrophilic groups) of (2) is dried in a dryer at 100°C, and its mass (M ⁇ ) is measured.
  • the insoluble component is then immersed in N,N-dimethylformamide at 25°C for 24 hours.
  • the insoluble component is then dried in a dryer at 100°C, and its mass (M ⁇ ) is measured.
  • the mass retention of the polyurethane having hydrophilic groups can be adjusted by the weight average molecular weight and degree of crosslinking of the polyurethane having hydrophilic groups used.
  • the weight average molecular weight of the polyurethane having hydrophilic groups can be adjusted by the weight average molecular weight of the polyurethane precursor used, the atmospheric temperature of the heat treatment, and the treatment time. The mass retention tends to increase as the weight average molecular weight increases, and the mass retention tends to increase as the degree of crosslinking of the polyurethane having hydrophilic groups increases.
  • the artificial leather of the present invention has a weight average molecular weight of 50,000 or more and 100,000 or less of components dissolved in N,N-dimethylformamide after immersing the artificial leather in N,N-dimethylformamide at 25°C for 24 hours (hereinafter, this may be abbreviated simply as "weight average molecular weight of dissolved components").
  • the dissolved components are components with relatively low molecular weights among polyurethanes having hydrophilic groups, which are components of artificial leather, and this "weight average molecular weight of dissolved components” essentially corresponds to the weight average molecular weight of the polyurethane precursor used to obtain polyurethanes having hydrophilic groups, which are components of artificial leather.
  • the strength and durability of the polyurethanes having hydrophilic groups can be increased.
  • the upper limit of the range to 100,000 or less, more preferably 90,000 or less, and even more preferably 80,000 or less, the artificial leather can have a soft feel.
  • the weight average molecular weight of the dissolved component can be determined by immersing an artificial leather in N,N-dimethylformamide at 25° C. for 24 hours, drying the components dissolved in the N,N-dimethylformamide, and then subjecting the resultant to gel permeation chromatography (GPC), and is measured under the following conditions: Equipment: For example, "HLC-8220" manufactured by Tosoh Corporation Column: For example, "TSKgel ⁇ -M” manufactured by Tosoh Corporation Solvent: N,N-dimethylformamide (DMF) Temperature: 40°C Calibration standard sample: Polystyrene (e.g., "TSK standard POLYSTYRENE” manufactured by Tosoh Corporation, etc.
  • GPC gel permeation chromatography
  • the weight average molecular weight of the soluble component can be adjusted by the weight average molecular weight of the polyurethane having a hydrophilic group used, the atmospheric temperature of the heat treatment, and the heat treatment time.
  • the artificial leather of the present invention preferably has an apparent density of 0.30 g/ cm3 or more and 0.40 g/ cm3 or less.
  • the apparent density of the artificial leather 0.30 g/ cm3 or more, more preferably 0.32 g/ cm3 or more, and even more preferably 0.34 g/ cm3 or more, the abrasion resistance of the artificial leather becomes excellent.
  • the apparent density 0.40 g/ cm3 or less preferably 0.38 g/ cm3 or less, the artificial leather can have a soft feel.
  • the apparent density of the artificial leather is calculated by measuring the thickness and mass per unit area of the artificial leather using the methods specified in JIS L1913:2010 "Testing methods for general nonwoven fabrics" 6.1.1 (thickness, method A) and 6.2 (mass per unit area), and using the following formula.
  • Apparent density of artificial leather (g/cm 3 ) mass per unit area of artificial leather (g/cm 2 )/thickness of artificial leather (cm).
  • the artificial leather of the present invention preferably has nap of 150 ⁇ m or more and 400 ⁇ m or less on at least one surface.
  • the length of this nap (hereinafter sometimes simply abbreviated as "napped length") 150 ⁇ m or more, preferably 200 ⁇ m or more, the artificial leather can have an elegant suede-like appearance.
  • the nap length 400 ⁇ m or less preferably 350 ⁇ m or less, it is possible to prevent dirt from getting into the nap, and the artificial leather can have a good appearance with less contamination even during long-term practical use.
  • the nap length is calculated by the following method. (1) Using a lint brush or the like, the above-mentioned nap is raised, and a cross section of the artificial leather is photographed at a magnification of 50 to 100 times using a scanning electron microscope (SEM, for example, "VHX-D500/D510" manufactured by Keyence Corporation). (2) In the SEM image taken, ten perpendicular lines are drawn at 200 ⁇ m intervals on a line ( LA in FIG. 1) parallel to the bottom surface ( LB in FIG. 1) of the artificial leather, according to the schematic diagram of the cross section of the artificial leather shown in FIG. 1.
  • SEM scanning electron microscope
  • Points P 1 to P 10 are marked on the intersections of the boundary line (L 0 ) between the napped portion (1 in the drawing) and the base portion (2 in the drawing), which is the portion other than the napped portion, and the perpendicular line.
  • Points Q 1 to Q 10 where the perpendicular lines passing through points P 1 to P 10 intersect with the tips of the napped layers are marked.
  • the distance between points P1 and Q1 is defined as R1 .
  • R2 to R10 are determined, and the average value (arithmetic mean) of R1 to R10 is calculated, which is defined as the nap length in the present invention.
  • the artificial leather of the present invention preferably has an abrasion loss of 30 mg or less when measured after 50,000 abrasion cycles in the Martindale abrasion test specified in "8.19 Abrasion resistance and discoloration due to friction" of JIS L1096:2005 “Testing methods for woven and knitted fabrics” under “8.19.5 Method E (Martindale method)". From the viewpoint of suppressing deterioration of the appearance of the artificial leather, it is more preferable that the abrasion loss is 25 mg or less.
  • the abrasion loss can be adjusted by adjusting the content of the polyurethane having hydrophilic groups in the artificial leather, the mass retention of the polyurethane having hydrophilic groups after immersing the artificial leather in N,N-dimethylformamide at 25°C for 24 hours, and the density change rate before and after entanglement of the nonwoven fabric made of ultrafine fiber-developing fibers within the preferred ranges described above.
  • the artificial leather obtained by the present invention can be suitably used as an interior material with a very elegant appearance as a surface material for furniture, chairs, and wall materials, and for seats, ceilings, and interiors in vehicle cabins such as automobiles, trains, and aircraft; as clothing materials used for uppers and trims of shoes such as shirts, jackets, casual shoes, sports shoes, men's shoes, and women's shoes, as well as bags, belts, wallets, and the like, and as parts of these; and as industrial materials such as wiping cloths, polishing cloths, and CD curtains.
  • the method for producing an artificial leather of the present invention preferably includes the following steps (1) to (4) in this order: (1) A step of forming a fibrous base material by subjecting a nonwoven fabric made of ultrafine fiber-developing fibers to an entanglement treatment so that the density change rate before and after entanglement is 2.5 to 3.5 times; (2) A step of impregnating the fibrous base material with an aqueous dispersion containing a polyurethane precursor having a weight average molecular weight of 50,000 to 100,000 and a crosslinking agent, and then performing a heat drying treatment to form an impregnated sheet containing the fibrous base material and a polyurethane having a hydrophilic group as components; (3) A step of expressing polyester ultrafine fibers from the ultrafine fiber-expressing fibers of the impregnated sheet to form a pre-heat treatment sheet containing, as components, a fibrous base material composed of polyester ultrafine fibers and polyurethane having a hydrophilic group;
  • Step of forming fibrous base material a nonwoven fabric made of ultrafine fiber development type fibers is subjected to an entanglement treatment so that the rate of change in density before and after entanglement is 2.5 to 3.5 times, thereby forming a fibrous base material.
  • sea-island composite fibers in which the sea component and island component are made of two thermoplastic resin components with different solvent solubility (two or three components if the island fiber is a core-sheath composite fiber), and the sea component is dissolved and removed using a solvent or the like to turn the island components into ultrafine fibers, because appropriate gaps can be provided between the island components, i.e., between the ultrafine fibers inside the fiber bundle, when the sea component is removed. This is because this can provide appropriate gaps between the island components, i.e., between the ultrafine fibers inside the fiber bundle, when the sea component is removed. From the perspective of the texture and surface quality of the artificial leather,
  • a method using a polymer mutual alignment body in which two components, the sea component and the island component (three components if the island fiber is a core-sheath composite fiber), are mutually aligned and spun using an islands-in-the-sea composite spinneret is preferred from the viewpoint of obtaining ultrafine fibers with a uniform single fiber diameter.
  • polyethylene, polypropylene, polystyrene, copolymer polyesters copolymerized with sodium sulfoisophthalic acid or polyethylene glycol, and polylactic acid can be used, but polystyrene and copolymer polyesters are preferably used from the viewpoints of spinnability and ease of elution.
  • the mass ratio of the sea component is 10% by mass or more, the island component is easily and sufficiently ultra-fine.
  • the mass ratio of the sea component is 80% by mass or less, the proportion of eluted components is small, improving productivity.
  • short-fiber or long-fiber nonwoven fabric can be used as the nonwoven fabric that constitutes the fibrous substrate, but short-fiber nonwoven fabric is preferred because it results in more fibers oriented in the thickness direction of the artificial leather than long-fiber nonwoven fabric, and this allows the artificial leather to have a highly dense surface when brushed.
  • the resulting ultrafine fiber-developing fibers are preferably subjected to a crimping process and then cut to a predetermined length to obtain raw cotton.
  • the crimping and cutting processes can be carried out using known methods.
  • the obtained raw cotton is made into a nonwoven fabric using a cross wrapper or the like.
  • the obtained nonwoven fabric is then entangled so that the apparent density change rate before and after entanglement is 2.5 to 3.5 times to obtain a fibrous base material.
  • the apparent density change rate before and after entanglement 2.5 times or more, more preferably 2.7 times or more, the fibers are sufficiently entangled and durability is improved.
  • the apparent density change rate 3.5 times or less, more preferably 3.2 times or less it is possible to maintain sufficient space between the fibers for applying polyurethane having hydrophilic groups.
  • Methods for entangling nonwoven fabric to obtain a fibrous base material include needle punching and water jet punching, but in order to make the apparent density change rate before and after entanglement within the above range, it is preferable to perform needle punching, which has high entanglement efficiency.
  • the rate of change in apparent density before and after entanglement is an index representing the degree of entanglement of the fibrous base material, and can be calculated by the following formula.
  • Apparent density change rate (times) before and after entanglement apparent density of fibrous base material after entanglement (g/cm 3 )/apparent density of nonwoven fabric before entanglement (g/cm 3 ).
  • the apparent density (g/ cm3 ) of the fiber web before and after entanglement is calculated by measuring the thickness and mass per unit area of the fiber web using the method specified in "6.1 Thickness (ISO method)", “6.1.1 A method” and “6.2 Mass per unit area (ISO method)” of JIS L1913:2010 "General nonwoven fabric testing methods", and using the following formula.
  • the fiber web includes both the nonwoven fabric before entanglement and the fibrous base material after entanglement.
  • Apparent density of a fibrous web (g/cm 3 ) mass per unit area of a fibrous web (g/cm 2 )/thickness of a fibrous web (cm).
  • Methods for entangling nonwoven fabrics to obtain a fibrous base material include needle punching and water jet punching, but to keep the apparent density change rate before and after entanglement within the above range, it is preferable to use needle punching, which has high entanglement efficiency.
  • silicone When entanglement is performed by needle punching, it is also a preferred embodiment to add 0.01 to 3% by mass of silicone to the raw cotton before entanglement in order to improve the smoothness of the raw cotton and improve entanglement efficiency.
  • silicone By adding silicone in an amount of 0.01% by mass or more, preferably 0.05% by mass or more, it is possible to increase the entanglement efficiency.
  • silicone by adding silicone in an amount of 3% by mass or less, more preferably 1% by mass or less, it is possible to prevent the fibrous base material from stretching too much during processing, which would cause the quality of the artificial leather to deteriorate.
  • needle punching When entanglement is performed by needle punching, in order to make the rate of change in apparent density before and after entanglement the above value, it is preferable to use needles equipped with barbs (notches) capable of gripping 5 to 15 fibers, and to perform needle punching at a punch density of 2000 fibers/cm2 or more and 4000 fibers/cm2 or less .
  • the apparent density of the fibrous substrate made of the composite fiber (ultrafine fiber development type fiber) after the entanglement treatment is preferably 0.20 g/cm 3 or more and 0.30 g/cm 3 or less.
  • the apparent density 0.20 g/cm 3 or more more preferably 0.23 g/cm 3 or more, the fibrous substrate can obtain sufficient shape stability and dimensional stability.
  • the apparent density 0.30 g/cm 3 or less more preferably 0.28 g/cm 3 or less, it is possible to maintain sufficient space for providing polyurethane having a hydrophilic group.
  • the fibrous base material is impregnated with an aqueous dispersion containing a polyurethane precursor having a weight average molecular weight of 50,000 or more and 100,000 or less and a crosslinking agent, and then a heating and drying treatment is performed to form an impregnated sheet containing the fibrous base material and a polyurethane having a hydrophilic group as components.
  • the concentration of the polyurethane precursor in the aqueous dispersion is preferably 3% by mass or more and 30% by mass or less. By making it 3% by mass or more, more preferably 5% by mass or more, the polyurethane precursor can be applied uniformly to the fibrous substrate even when the amount of polyurethane precursor applied is small. On the other hand, by making it 30% by mass or less, more preferably 15% by mass or less, the storage stability of the aqueous dispersion can be improved.
  • the weight average molecular weight of the polyurethane precursor used in the present invention is 50,000 or more and 100,000 or less.
  • the strength and durability of the polyurethane having hydrophilic groups can be increased.
  • the 100,000 or less, more preferably 90,000 or less, and even more preferably 80,000 or less it is possible to produce artificial leather with a soft feel.
  • the weight average molecular weight of the polyurethane precursor can be measured in the same manner as the weight average molecular weight of the dissolved component described above.
  • coagulation can be performed using a coagulation method commonly used in this field, such as a dry heat coagulation method or a liquid coagulation method.
  • a dry heat coagulation method it is preferable to apply the aqueous dispersion to the fibrous base material, heat treat it at a temperature of 120°C to 180°C, and perform dry heat coagulation to apply a polyurethane having hydrophilic groups to the fibrous base material.
  • an inorganic salt can be contained in the aqueous dispersion.
  • the aqueous dispersion can be given heat-sensitive coagulation properties.
  • heat-sensitive coagulation properties refer to the property that when the aqueous dispersion is heated, the fluidity of the aqueous dispersion decreases and the aqueous dispersion coagulates when a certain temperature (heat-sensitive coagulation temperature) is reached.
  • the heat-sensitive coagulation temperature of the aqueous dispersion is preferably 55°C or higher and 80°C or lower.
  • the heat-sensitive coagulation temperature is preferably 55°C or higher, more preferably 60°C or higher.
  • gelation during preparation and storage of the aqueous dispersion can be suppressed.
  • 80°C or lower more preferably 70°C or lower, coagulation of the polyurethane precursor proceeds before water evaporates from the fibrous base material, and a structure similar to that obtained by wet coagulation of solvent-based polyurethane can be formed, i.e., a structure in which the polyurethane does not strongly bind the fibers, making it possible to achieve good flexibility and resilience.
  • an inorganic salt when used as a heat-sensitive coagulant, it is preferable to use an inorganic salt containing a monovalent cation.
  • the above-mentioned inorganic salt containing a monovalent cation is preferably sodium chloride and/or sodium sulfate.
  • An inorganic salt containing a monovalent cation which has a small ionic valence, has little effect on the stability of the aqueous dispersion, and by adjusting the amount added, the heat-sensitive coagulation temperature can be strictly controlled while ensuring the stability of the aqueous dispersion.
  • the content of the monovalent cation-containing inorganic salt in the aqueous dispersion is preferably 10% by mass or more and 50% by mass or less with respect to the polyurethane precursor.
  • the content 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 aqueous dispersion act uniformly on the polyurethane precursor particles, and coagulation can be completed quickly at a specific heat-sensitive coagulation temperature. This makes it possible to obtain a more remarkable effect in proceeding with the coagulation of the polyurethane precursor in a state in which a large amount of moisture is contained in the fibrous base material as described above.
  • the inorganic salt acts as an inhibitor in the fusion of the polyurethane precursor particles, and it is also possible to suppress the hardening of the polyurethane precursor due to the formation of a continuous film.
  • the content 50% by mass or less it is possible to leave an appropriate continuous film structure of the polyurethane precursor and suppress the deterioration of physical properties. It is also possible to maintain the stability of the aqueous dispersion.
  • the aqueous dispersion contains a crosslinking agent.
  • the crosslinking agent By using the crosslinking agent to introduce a three-dimensional network structure into the polyurethane precursor, physical properties such as abrasion resistance can be improved.
  • the concentration of the crosslinking agent in the aqueous dispersion is preferably 1% by mass or more and 10% by mass or less relative to the mass of the polyurethane precursor.
  • concentration of the crosslinking agent in the aqueous dispersion 1% by mass or more, more preferably 2% by mass or more, the crosslinking agent can introduce a greater amount of three-dimensional network structure into the polyurethane precursor, resulting in an artificial leather with excellent abrasion resistance, etc.
  • the concentration of the crosslinking agent 10% by mass or less, more preferably 7% by mass or less, it is possible to prevent excess crosslinking agent 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.
  • the crosslinking agent in the method for producing artificial leather of the present invention is preferably a carbodiimide-based crosslinking agent and/or a blocked isocyanate crosslinking agent.
  • a three-dimensional crosslinking structure can be imparted to the molecules of the polymeric elastomer in the artificial leather by 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 the artificial leather can be dramatically improved in physical properties such as durability and abrasion resistance while maintaining its flexibility.
  • a heat drying process is carried out to form an impregnated sheet containing the fibrous base material and polyurethane having hydrophilic groups as its components.
  • the temperature for the heat drying process is preferably 110°C or higher, and more preferably 120°C or higher.
  • the heat drying process temperature is preferably 110°C or higher, not only can the drying efficiency of the sheet be increased, but the progress of the crosslinking reaction can be promoted, and the physical properties of the artificial leather, such as durability and abrasion resistance, can be improved.
  • the heat drying process temperature is set at 180°C or lower, or 170°C or lower, thermal deterioration of polyurethane having hydrophilic groups can be suppressed.
  • the time for the heat drying process is preferably 5 minutes or more and 30 minutes or less. Heating for 5 minutes or more, more preferably 10 minutes or more, can promote the progress of the crosslinking reaction. Heating for 30 minutes or less, preferably 25 minutes or less, can suppress thermal degradation of polyurethane having hydrophilic groups due to excessive heating.
  • polyester ultrafine fibers are developed from the ultrafine fiber-developing fibers of the impregnated sheet, and a pre-heat treatment sheet is formed containing, as components, a fibrous base material composed of polyester ultrafine fibers and polyurethane having hydrophilic groups.
  • the ultrafine fiber processing can be carried out, for example, by immersing the islands-in-sea composite fibers in a solvent and then carrying out a heat treatment.
  • the solvent for dissolving the sea component can be appropriately selected depending on the type of sea component.
  • an alkaline aqueous solution such as an aqueous sodium hydroxide solution can be used.
  • the molar concentration of the alkaline aqueous solution be 3 mol/L or less to prevent excessive deterioration of the polyurethane containing hydrophilic groups.
  • the pre-heat-treatment sheet is subjected to a heat treatment at an atmospheric temperature of 150° C. or more and 200° C. or less for 5 minutes or more and 20 minutes or less.
  • This heat treatment is carried out after the pre-heat treatment sheet is obtained, but it is preferable to carry it out immediately after the ultrafine fiber processing to prevent deterioration of quality due to elongation during the process.
  • the preferred method of heat treatment is to use a hot air dryer such as a floater dryer, drum dryer, or pin tenter.
  • the atmospheric temperature be 150°C or higher and 200°C or lower.
  • the temperature at 150°C or higher, and more preferably at 155°C or higher, the adhesion between the ultrafine fibers and the polyurethane having hydrophilic groups is improved, and not only can the strength and abrasion resistance of the artificial leather be improved, but also a portion of the polyurethane having hydrophilic groups can be reduced in molecular weight, increasing the flexibility of the artificial leather.
  • the temperature at 200°C or lower preferably 190°C or lower, and more preferably 180°C or lower, a portion of the polyurethane having hydrophilic groups can be gradually reduced in molecular weight.
  • the heating time is between 5 and 20 minutes.
  • the heating time is set to 5 minutes or more, and preferably 6 minutes or more, the adhesion between the ultrafine fibers and the polyurethane having hydrophilic groups is improved, and the strength and abrasion resistance of the artificial leather can be improved.
  • the heating time is set 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 caused by excessive reduction in the molecular weight of the polyurethane having hydrophilic groups.
  • the method for producing the artificial leather of the present invention preferably includes a dyeing step for dyeing the artificial leather.
  • a dyeing process various methods commonly used in this field can be adopted.
  • a liquid flow dyeing process using a jigger dyeing machine or a liquid flow dyeing machine a dip dyeing process such as a thermosol dyeing process using a continuous dyeing machine, or a printing process on the napped surface by roller printing, screen printing, inkjet printing, sublimation printing, vacuum sublimation printing, etc. can be used.
  • liquid flow dyeing machine since it is possible to soften the unbrushed artificial leather or artificial leather by imparting a kneading effect to the unbrushed artificial leather or artificial leather while dyeing it.
  • various resin finishing processes can be applied after dyeing, if necessary.
  • finishing treatments can be applied using softeners such as silicone, antistatic agents, water repellents, flame retardants, light fasteners, antibacterial agents, etc. in the same bath as dyeing or after dyeing.
  • softeners such as silicone, antistatic agents, water repellents, flame retardants, light fasteners, antibacterial agents, etc. in the same bath as dyeing or after dyeing.
  • a nap raising step for forming naps is also preferable to include a nap raising step for forming naps, whether before or after the dyeing step.
  • the method for forming naps is not particularly limited, and various methods commonly used in this field, such as buffing with sandpaper, can be used.
  • a lubricant such as a silicone emulsion can be applied to the surface of the artificial leather before the nap-raising treatment. Also, by applying an antistatic agent before the nap-raising treatment, grinding dust generated from the artificial leather during grinding is less likely to accumulate on the sandpaper. In this way, the artificial leather is formed.
  • the artificial leather can be subjected to post-processing such as perforation, embossing, laser processing, pinsonic processing, and printing, as necessary.
  • Average single fiber diameter ( ⁇ m) The average single fiber diameter ( ⁇ m) was measured and calculated by the above-mentioned method using a scanning electron microscope (SEM) "VHX-D500/D510" manufactured by Keyence Corporation.
  • Mass retention (%) of polyurethane having hydrophilic group The mass retention (%) of the polyurethane having a hydrophilic group was measured and calculated by the above-mentioned method.
  • Pile length ( ⁇ m) The nap length was measured and calculated by the above-mentioned method using a scanning electron microscope (SEM) "VHX-D500/D510" manufactured by Keyence Corporation.
  • Polyurethane precursor The polyurethane precursors used in the examples and comparative examples are as follows.
  • PU-A A polyurethane precursor having a weight average molecular weight of 80,000, which uses polytetramethylene glycol as a polymer polyol, MDI as an organic diisocyanate, 2,2-dimethylolpropionic acid as an active hydrogen component-containing compound having a hydrophilic group, and ethylene glycol as a chain extender.
  • PU-B A polyurethane precursor having a weight average molecular weight of 55,000, which uses polytetramethylene glycol as a polymer polyol, MDI as an organic diisocyanate, 2,2-dimethylolpropionic acid as an active hydrogen component-containing compound having a hydrophilic group, and ethylene glycol as a chain extender.
  • PU-C A polyurethane precursor having a weight average molecular weight of 90,000, which uses polytetramethylene glycol as a polymer polyol, MDI as an organic diisocyanate, 2,2-dimethylolpropionic acid as an active hydrogen component-containing compound having a hydrophilic group, and ethylene glycol as a chain extender.
  • PU-D A polyurethane precursor having a weight average molecular weight of 80,000, which uses a polyol obtained by copolymerizing polytetramethylene glycol and polyhexamethylene carbonate in a molar ratio of 3:1 as the high molecular weight polyol, MDI as the organic diisocyanate, 2,2-dimethylolpropionic acid as the active hydrogen component-containing compound having a hydrophilic group, and ethylene glycol as the chain extender.
  • PU-E A polyurethane precursor having a weight average molecular weight of 110,000, which uses polytetramethylene glycol as a polymer polyol, MDI as an organic diisocyanate, 2,2-dimethylolpropionic acid as an active hydrogen component-containing compound having a hydrophilic group, and ethylene glycol as a chain extender.
  • Example 1 ⁇ Step of forming fibrous base material> A polyester copolymerized with 8 mol% of sodium 5-sulfoisophthalate was used as the sea component, and a polyethylene terephthalate having an intrinsic viscosity of 0.73 was used as the island component.
  • the melt spinning was performed using an islands-in-sea composite spinneret with 16 islands/hole under the conditions of a spinning temperature of 285°C, an islands/sea mass ratio of 80/20, a discharge rate of 1.6 g/min/hole, and a spinning speed of 1100 m/min.
  • the obtained fiber was then stretched 3.7 times in an oil solution bath, and 0.5% by mass of dimethyl silicone was added to the fiber mass (hereinafter, the "amount of silicone added to the raw cotton" is described as 0.5% by mass), and then cut to a length of 51 mm to obtain raw cotton of islands-in-sea composite fiber with a single fiber fineness of 3.8 dtex.
  • the raw cotton of the islands-in-sea composite fiber was then used to form a laminated web with an apparent density of 0.09 g/ cm3 through carding and cross-wrapping processes.
  • the laminated web was needle-punched at a punch density of 3,500/ cm2 using needles equipped with barbs capable of gripping a maximum of 10 raw cotton fibers (hereinafter, the "maximum number of needle barbs that can be gripped" is referred to as 10) to obtain a fibrous base material having a basis weight of 700 g/ m2 , a thickness of 2.6 mm, and an apparent density of 0.27 g/ cm3 (a density change rate of 3.0 times before and after entanglement).
  • the obtained fibrous base material was immersed in hot water at a temperature of 98°C for 2 minutes to cause it to shrink, and then dried at a temperature of 100°C for 5 minutes to obtain a fibrous base material consisting of a nonwoven fabric of islands-in-the-sea type composite fibers.
  • aqueous dispersion containing 11 parts by mass of "PU-A” as a polyurethane precursor, 1 part by mass of crosslinking agent A (a carbodiimide crosslinking agent, "Carbodilite V-02-L2” manufactured by Nisshinbo Chemical Inc.), 5 parts by mass of sodium sulfate, and 83 parts by mass of water was prepared.
  • the fibrous base material was impregnated with the aqueous dispersion, and then squeezed with a mangle so that the pick-up rate of the aqueous dispersion was 200%, and further heated with hot air at 120°C for 20 minutes to coagulate the polyurethane precursor and form a crosslinked structure consisting of N-acylurea bonds and/or isourea bonds, thereby obtaining an impregnated sheet consisting of a nonwoven fabric of islands-in-the-sea type composite fibers and a polyurethane having a hydrophilic group.
  • ⁇ Step of forming pre-heat treatment sheet> The obtained impregnated sheet was immersed in a 5% aqueous sodium hydroxide solution, and then squeezed with a mangle so that the pick-up rate of the aqueous sodium hydroxide solution became 100%, and further heat-treated with steam at 95° C. for 10 minutes to alkali-decompose the sea component of the islands-in-sea type composite fibers, and then the excess sodium hydroxide and sodium sulfate were washed away with water to obtain a pre-heat-treatment sheet.
  • ⁇ Heat treatment process> The water-washed pre-heat-treatment sheet was heat-treated for 10 minutes in a pin tenter with an atmospheric temperature raised to 160° C. to obtain a sheet composed of a fibrous base material made of ultrafine fibers and polyurethane having hydrophilic groups.
  • the resulting napped sheet was dyed black using a disperse dye at a temperature of 120°C using a liquid jet dyeing machine.
  • the dyed napped sheet was dried in a dryer to obtain an artificial leather containing polyurethane with an average single fiber diameter of 4.4 ⁇ m and 23% by mass of hydrophilic groups.
  • the resulting artificial leather had a soft feel and excellent durability. The results are shown in Table 1.
  • Example 2 An artificial leather containing polyurethane having an average single fiber diameter of ultrafine fibers of 4.4 ⁇ m and 23 mass % of hydrophilic groups was obtained in the same manner as in Example 1, except that in the step of forming an impregnated sheet, the polyurethane precursor was changed to "PU-B". The obtained artificial leather had a soft feel and excellent durability. The results are shown in Table 1.
  • Example 3 An artificial leather containing polyurethane having an average single fiber diameter of 4.4 ⁇ m and 23 mass % of hydrophilic groups was obtained in the same manner as in Example 1, except that in the step of forming an impregnated sheet, the polyurethane precursor was changed to "PU-C".
  • the artificial leather obtained had a slightly resistant feel, but had a soft texture and excellent durability. The results are shown in Table 1.
  • Example 4 An artificial leather was obtained in the same manner as in Example 1, except that in the step of forming an impregnated sheet, the pick-up rate of the aqueous dispersion was changed to 150%, and the ultrafine fibers had an average single fiber diameter of 4.4 ⁇ m and contained 18% by mass of polyurethane having a hydrophilic group. The obtained artificial leather had a soft feel and excellent durability. The results are shown in Table 1.
  • Example 5 An artificial leather containing polyurethane having an average single fiber diameter of 4.4 ⁇ m and 23 mass % of hydrophilic groups was obtained in the same manner as in Example 1, except that in the step of forming an impregnated sheet, the polyurethane precursor was changed to "PU-D".
  • the artificial leather obtained had a slightly resistant feel but a soft texture and excellent durability. The results are shown in Table 1.
  • Example 6 An artificial leather was obtained in the same manner as in Example 1, except that in the ⁇ step of performing heat treatment>, the atmospheric temperature of the heat treatment was changed to 180° C., and the ultrafine fibers had an average single fiber diameter of 4.4 ⁇ m and contained 23% by mass of polyurethane having a hydrophilic group. The obtained artificial leather had a soft feel and excellent durability. The results are shown in Table 1.
  • Example 7 An artificial leather was obtained in the same manner as in Example 1, except that the heat treatment time was changed to 15 minutes in the ⁇ step of performing heat treatment>, in which the average single fiber diameter of the ultrafine fibers was 4.4 ⁇ m and the polyurethane contained 23 mass % of a hydrophilic group.
  • the obtained artificial leather had a soft feel and excellent durability. The results are shown in Table 2.
  • Example 8 An artificial leather was obtained in the same manner as in Example 1, except that in the ⁇ step of performing heat treatment>, the atmospheric temperature of the heat treatment was changed to 150° C., and the ultrafine fibers had an average single fiber diameter of 4.4 ⁇ m and contained 23% by mass of polyurethane having hydrophilic groups.
  • the obtained artificial leather had a slightly resistant feel, but had a soft texture and excellent durability. The results are shown in Table 2.
  • Example 9 An artificial leather was obtained in the same manner as in Example 1, except that in the ⁇ step of forming a fibrous base material>, dimethyl silicone was not added to the raw cotton, and the average single fiber diameter of the ultrafine fibers was 4.4 ⁇ m, and the artificial leather contained 23 mass % of polyurethane having a hydrophilic group. The obtained artificial leather had a soft feel and excellent durability. The results are shown in Table 2.
  • Example 10 In the ⁇ step of forming a fibrous base material>, dimethyl silicone was not added to the raw cotton, and needle punching was performed with a punch count of 3000/ cm2 , in the same manner as in Example 1, to obtain an artificial leather having an average single fiber diameter of ultrafine fibers of 4.4 ⁇ m and containing 23% by mass of polyurethane having a hydrophilic group. The obtained artificial leather had a soft feel and excellent durability. The results are shown in Table 2.
  • Example 1 An artificial leather was obtained in the same manner as in Example 1, except that in the ⁇ step of performing heat treatment>, the heat treatment time was changed to 30 minutes, and the ultrafine fibers had an average single fiber diameter of 4.4 ⁇ m and contained 23 mass % of polyurethane having hydrophilic groups. The obtained artificial leather had a soft feel, but was significantly inferior in durability. The results are shown in Table 3.
  • Example 3 An artificial leather was obtained in the same manner as in Example 1, except that in the step of forming an impregnated sheet, the pick-up rate of the aqueous dispersion was changed to 110%, and the ultrafine fibers had an average single fiber diameter of 4.4 ⁇ m and contained 13% by mass of polyurethane having hydrophilic groups.
  • the artificial leather obtained had a soft feel, but was significantly inferior in durability. The results are shown in Table 3.
  • Example 4 An artificial leather was obtained in the same manner as in Example 1, except that in the step of forming an impregnated sheet, the pick-up rate of the aqueous dispersion was changed to 250%, and the average single fiber diameter of the ultrafine fibers was 4.4 ⁇ m, and the artificial leather contained 29% by mass of polyurethane having hydrophilic groups.
  • the artificial leather obtained had excellent durability, but had a hard feel. The results are shown in Table 3.
  • Example 7 An artificial leather was obtained in the same manner as in Example 2, except that the heat treatment time was changed to 3 minutes in the ⁇ step of performing heat treatment>, in which the average single fiber diameter of the ultrafine fibers was 4.4 ⁇ m and the polyurethane contained 23 mass % of a hydrophilic group.
  • the obtained artificial leather had a soft feel, but was significantly inferior in durability. The results are shown in Table 4.

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Abstract

Artificial leather including, as constituent elements, a fibrous base material configured from fine polyester fibers having an average single-fiber diameter of 0.1-10.0 μm, and polyurethane that has a hydrophilic group, wherein the content ratio of the polyurethane having a hydrophilic group in the artificial leather is 15-25 mass%, the mass holding ratio of the polyurethane having a hydrophilic group after the artificial leather is immersed for 24 hours in 25°C N,N-dimethyl formamide is 50-80 mass%, and the weight-average molecular weight of a component dissolved in 25°C N,N-dimethyl formamide after the artificial leather is immersed for 24 hours in the 25°C N,N-dimethyl formamide is 50,000-100,000. Provided are artificial leather and a method for manufacturing the same, with which both soft texture and exceptional durability are achieved while using an environmentally conscious process in which no organic solvents are used.

Description

人工皮革およびその製造方法Artificial leather and its manufacturing method
　本発明は、人工皮革およびその製造方法に関する。 The present invention relates to artificial leather and a method for producing the same.
　主として不織布等の繊維質基材とポリウレタンからなる人工皮革は、天然皮革にない優れた特徴を有しており、衣料や家具、車輛内装材用途等にその使用が年々広がってきている。そして、このような人工皮革を製造するにあたっては、従来の有機溶剤系のポリウレタンを用いる方法に代えて、より環境に配慮された、水中にポリウレタン樹脂を分散させた水分散型ポリウレタンを用いる方法が検討されている。 　Artificial leather, which is mainly made of a fibrous base material such as nonwoven fabric and polyurethane, has excellent characteristics that natural leather does not have, and its use is expanding year by year in applications such as clothing, furniture, and vehicle interior materials. In addition, in order to manufacture such artificial leather, a more environmentally friendly method of using water-dispersed polyurethane, in which polyurethane resin is dispersed in water, is being considered as an alternative to the conventional method of using organic solvent-based polyurethane.
　これまでに、このような人工皮革を得るための方法がいくつか提案されている。 Several methods have been proposed to obtain such artificial leather.
　例えば、特許文献１では、繊維質基材に特定のケン化度および特定の重合度のポリビニルアルコールを特定量付与した後に、水分散型ポリウレタンを付与し、その後ポリビニルアルコールを除去する方法が提案されている。そして、この方法によれば、優美な外観と柔軟な風合いを達成し、さらに良好な耐摩耗性を有するシート状物を得ることができる旨が記載されている。 For example, Patent Document 1 proposes a method in which a specific amount of polyvinyl alcohol with a specific degree of saponification and a specific degree of polymerization is applied to a fibrous substrate, then a water-dispersible polyurethane is applied, and then the polyvinyl alcohol is removed. It is described that this method achieves an elegant appearance and soft feel, and also makes it possible to obtain a sheet-like material with good abrasion resistance.
　また、特許文献２では、極細繊維発現型繊維からなる繊維質基材に、特定の高分子弾性体、特定量の１価陽イオン含有無機塩、および架橋剤を含有する水分散液を含浸せしめ、次いで特定の温度で加熱処理を行う高分子弾性体含浸工程、極細繊維発現工程、乾燥工程および起毛工程をこの順に含む方法が提案されている。そして、この方法によれば、柔軟な風合いと優れた耐光性を両立したシート状物が得られる旨が記載されている。 Patent Document 2 also proposes a method including, in this order, a polymer elastomer impregnation step in which a fibrous substrate made of ultrafine fiber-producing fibers is impregnated with an aqueous dispersion containing a specific polymer elastomer, a specific amount of inorganic salt containing monovalent cations, and a crosslinking agent, and then a heat treatment is performed at a specific temperature, a microfiber producing step, a drying step, and a nap raising step. It is described that this method produces a sheet-like material that combines a soft texture with excellent light resistance.
　そして、特許文献３では、海島型複合繊維から海成分を除去する前後に、それぞれ、水性エマルジョンのポリウレタンを含浸、固着させる方法が提案されている。そして、この方法によれば、物理的機械的特性、耐磨耗性および外観が最適であるスエード革型極細繊維状不織布が製造できる旨が記載されている。 Patent Document 3 proposes a method of impregnating and fixing an aqueous emulsion of polyurethane before and after removing the sea component from islands-in-the-sea composite fibers. It also describes that this method makes it possible to produce a suede-type ultrafine fiber nonwoven fabric with optimal physical and mechanical properties, abrasion resistance, and appearance.
　さらに、特許文献４では、極細繊維発現工程の前後に、それぞれ、極細繊維発現型繊維からなる繊維質基材に、特定の高分子弾性体、特定量の１価陽イオン含有無機塩、および架橋剤を含有する水分散液を含浸せしめ、次いで特定の温度で加熱処理を行う高分子弾性体含浸工程を行う方法が提案されている。そして、この方法によれば、柔軟性、耐薬品性および耐染色性に優れるシート状物が得られる旨が記載されている。 Furthermore, Patent Document 4 proposes a method for carrying out a polymer elastomer impregnation step in which a fibrous substrate made of ultrafine fiber-producing fibers is impregnated with an aqueous dispersion containing a specific polymer elastomer, a specific amount of an inorganic salt containing a monovalent cation, and a crosslinking agent before and after the ultrafine fiber producing step, and then a heat treatment is carried out at a specific temperature. It is described that this method produces a sheet-like material with excellent flexibility, chemical resistance, and dye resistance.
国際公開第２０１４／０４２２４１号International Publication No. 2014/042241 国際公開第２０２１／１２５０３２号International Publication No. 2021/125032 特開２００３－３０６８７８号公報JP 2003-306878 A 国際公開第２０２１／１２５０２９号International Publication No. 2021/125029
　特許文献１に開示された方法においては、ポリウレタンと極細繊維との間の接着状態が適度に調整されることで、柔軟な風合いと耐久性の両立を達成しているものの、ポリビニルアルコールの溶出処理を必要とするため、製造効率の点で改善の余地がある。 In the method disclosed in Patent Document 1, the adhesive state between the polyurethane and the ultrafine fibers is appropriately adjusted to achieve both a soft feel and durability, but since a polyvinyl alcohol leaching process is required, there is room for improvement in terms of production efficiency.
　特許文献２に開示された方法においても、ポリウレタンと極細繊維との間の接着状態が適度に緩和され、ポリビニルアルコールの付与をしなくとも、柔軟な風合いを達成している。しかしながら、耐摩耗性をはじめとする耐久性の観点では改善の余地がある。 The method disclosed in Patent Document 2 also moderates the adhesion between the polyurethane and the ultrafine fibers, achieving a soft texture without adding polyvinyl alcohol. However, there is room for improvement in terms of durability, including abrasion resistance.
　特許文献３、４に開示された方法においては、ポリウレタンを２回付与することで、柔軟な風合いと耐久性の両立を達成している。しかしながら、ポリウレタンを２段階に分けて付与するため、製造効率の点で改善の余地がある。 In the methods disclosed in Patent Documents 3 and 4, polyurethane is applied twice to achieve both a soft feel and durability. However, because polyurethane is applied in two stages, there is room for improvement in terms of production efficiency.
　そこで、本発明の目的は、上記の課題に鑑み、有機溶剤を使用しない、環境配慮型のプロセスでありながら、柔軟な風合いと優れた耐久性とを両立した人工皮革およびその製造方法を提供することにある。 In view of the above problems, the object of the present invention is to provide an artificial leather and a manufacturing method thereof that combines a soft feel with excellent durability while being produced using an environmentally friendly process that does not use organic solvents.
　上記の目的を達成すべく本発明者らが検討を重ねた結果、人工皮革中の水分散型ポリウレタンとして、親水性基を有するポリウレタンを用い、さらに、Ｎ，Ｎ－ジメチルホルムアミド（以降、ＤＭＦと略記することがある）に浸漬後の親水性基を有するポリウレタンの質量保持率、および、ＤＭＦに溶解する成分の重量平均分子量が特定の範囲内となるように調整することで、人工皮革の柔軟性と、耐摩耗性を高いレベルで両立可能なことを見出した。加えて、製造工程において、繊維質基材における繊維の絡合度を特定の範囲まで高めた場合に、人工皮革がより高い耐久性を有することを見出した。 As a result of extensive research by the inventors to achieve the above object, they have found that by using a polyurethane having hydrophilic groups as the water-dispersible polyurethane in the artificial leather, and further adjusting the mass retention rate of the polyurethane having hydrophilic groups after immersion in N,N-dimethylformamide (hereinafter sometimes abbreviated as DMF) and the weight average molecular weight of the components soluble in DMF to be within a specific range, it is possible to achieve a high level of both flexibility and abrasion resistance in the artificial leather. In addition, they have found that when the degree of entanglement of fibers in the fibrous base material is increased to a specific range during the manufacturing process, the artificial leather has higher durability.
　本発明は、これらの知見に基づいて完成に至ったものであり、本発明によれば、以下の発明が提供される。
［１］　平均単繊維直径が０．１μｍ以上１０．０μｍ以下のポリエステル極細繊維で構成されてなる繊維質基材と、親水性基を有するポリウレタンと、を構成要素として含む人工皮革であって、前記人工皮革における前記親水性基を有するポリウレタンの含有割合が１５質量％以上２５質量％以下であって、前記人工皮革を２５℃のＮ，Ｎ－ジメチルホルムアミドに２４時間浸漬させた後の前記親水性基を有するポリウレタンの質量保持率が５０質量%以上８０質量%以下であり、前記人工皮革を２５℃のＮ，Ｎ－ジメチルホルムアミドに２４時間浸漬させた後に該Ｎ，Ｎ－ジメチルホルムアミド中に溶解している成分の重量平均分子量が５００００以上１０００００以下である、人工皮革。
［２］　人工皮革の見掛け密度が０．３０ｇ／ｃｍ３以上０．４０ｇ／ｃｍ３以下である、前記［１］に記載の人工皮革。
［３］　前記親水性基を有するポリウレタンがポリエステルポリオールに由来する構成成分を含む、前記［１］または［２］に記載の人工皮革。
［４］　前記親水性基を有するポリウレタンがさらにポリカーボネートポリオールに由来する構成成分を含む、前記［３］に記載の人工皮革。
［５］　前記親水性基を有するポリウレタンが、N－アシルウレア結合および／またはイソウレア結合を有する、前記［１］～［４］のいずれかに記載の人工皮革。
［６］　下記（１）～（４）の工程をこの順に含む、前記［１］～［５］のいずれかに記載の人工皮革の製造方法：
（１）極細繊維発現型繊維からなる不織布に、絡合前後での密度変化率が２．５倍以上３．５倍以下となるように絡合処理を施し、繊維質基材を形成する工程；
（２）前記繊維質基材に、重量平均分子量が５００００以上１０００００以下のポリウレタン前駆体と、架橋剤とを含有する水分散液を含浸せしめ、次いで、加熱乾燥処理を行って繊維質基材と、親水性基を有するポリウレタンと、を構成要素として含む、含浸シートを形成する工程；
（３）前記含浸シートの極細繊維発現型繊維からポリエステル極細繊維を発現させ、ポリエステル極細繊維で構成されてなる繊維質基材と、前記親水性基を有するポリウレタンと、を構成要素として含む熱処理前シートを形成する工程；
（４）前記熱処理前シートを、１５０℃以上２００℃以下の雰囲気温度で、５分以上２０分以下、熱処理を行う工程。
［７］　前記架橋剤がカルボジイミド系架橋剤である、前記［６］に記載の人工皮革の製造方法。
［８］　前記（１）の工程において、前記極細繊維発現型繊維の質量に対し０．０１質量％以上３質量％以下のシリコーンを付与する、前記［６］または［７］に記載の人工皮革の製造方法。 The present invention has been completed based on these findings, and provides the following inventions.
[1] An artificial leather comprising, as components, a fibrous base material composed of polyester ultrafine fibers having an average single fiber diameter of 0.1 μm or more and 10.0 μm or less, and a polyurethane having a hydrophilic group, wherein the content of the polyurethane having a hydrophilic group in the artificial leather is 15% by mass or more and 25% by mass or less, the mass retention rate of the polyurethane having a hydrophilic group after the artificial leather is immersed in N,N-dimethylformamide at 25° C. for 24 hours is 50% by mass or more and 80% by mass or less, and the weight average molecular weight of a component dissolved in N,N-dimethylformamide after the artificial leather is immersed in N,N-dimethylformamide at 25° C. for 24 hours is 50,000 or more and 100,000 or less.
[2] The artificial leather according to the above [1], wherein the apparent density of the artificial leather is 0.30 g/ cm3 or more and 0.40 g/ cm3 or less.
[3] The artificial leather according to [1] or [2], wherein the polyurethane having a hydrophilic group contains a component derived from a polyester polyol.
[4] The artificial leather according to [3] above, wherein the polyurethane having a hydrophilic group further contains a constituent component derived from a polycarbonate polyol.
[5] The artificial leather according to any one of [1] to [4], wherein the polyurethane having a hydrophilic group has an N-acylurea bond and/or an isourea bond.
[6] A method for producing an artificial leather according to any one of the above [1] to [5], comprising the following steps (1) to (4) in this order:
(1) A step of forming a fibrous base material by subjecting a nonwoven fabric made of ultrafine fiber-developing fibers to an entanglement treatment so that the density change rate before and after entanglement is 2.5 to 3.5 times;
(2) A step of impregnating the fibrous base material with an aqueous dispersion containing a polyurethane precursor having a weight average molecular weight of 50,000 to 100,000 and a crosslinking agent, and then performing a heat drying treatment to form an impregnated sheet containing the fibrous base material and a polyurethane having a hydrophilic group as components;
(3) A step of expressing polyester ultrafine fibers from the ultrafine fiber-expressing fibers of the impregnated sheet to form a pre-heat treatment sheet containing, as components, a fibrous base material composed of polyester ultrafine fibers and the polyurethane having a hydrophilic group;
(4) A step of subjecting the pre-heat-treatment sheet to a heat treatment at an atmospheric temperature of 150° C. or more and 200° C. or less for 5 minutes or more and 20 minutes or less.
[7] The method for producing an artificial leather according to [6], wherein the crosslinking agent is a carbodiimide-based crosslinking agent.
[8] The method for producing an artificial leather according to [6] or [7], wherein in the step (1), 0.01% by mass or more and 3% by mass or less of silicone is added to the mass of the ultrafine fiber development type fiber.
　本発明によれば、柔軟な風合いと優れた耐摩耗性を両立した人工皮革が得られる。 The present invention makes it possible to obtain artificial leather that combines a soft feel with excellent abrasion resistance.
図１は、本発明の人工皮革にかかる平均立毛長の測定方法を説明するための断面概念図である。FIG. 1 is a schematic cross-sectional view illustrating a method for measuring the average nap length of the artificial leather of the present invention.
　本発明の人工皮革は、平均単繊維直径が０．１μｍ以上１０．０μｍ以下のポリエステル極細繊維で構成されてなる繊維質基材と、親水性基を有するポリウレタンと、を構成要素として含む人工皮革であって、前記人工皮革における前記親水性基を有するポリウレタンの含有割合が１５質量％以上２５質量％以下であって、前記人工皮革を２５℃のＮ，Ｎ－ジメチルホルムアミドに２４時間浸漬させた後の前記親水性基を有するポリウレタンの質量保持率が５０質量%以上８０質量%以下であり、前記人工皮革を２５℃のＮ，Ｎ－ジメチルホルムアミドに２４時間浸漬させた後に該Ｎ，Ｎ－ジメチルホルムアミド中に溶解している成分の重量平均分子量が５００００以上１０００００以下である。 The artificial leather of the present invention is an artificial leather containing as its components a fibrous base material composed of polyester ultrafine fibers having an average single fiber diameter of 0.1 μm or more and 10.0 μm or less, and a polyurethane having a hydrophilic group, the content of the polyurethane having a hydrophilic group in the artificial leather is 15% by mass or more and 25% by mass or less, the mass retention rate of the polyurethane having a hydrophilic group after the artificial leather is immersed in N,N-dimethylformamide at 25°C for 24 hours is 50% by mass or more and 80% by mass or less, and the weight average molecular weight of the component dissolved in N,N-dimethylformamide after the artificial leather is immersed in N,N-dimethylformamide at 25°C for 24 hours is 50,000 or more and 100,000 or less.
　以下にこの構成要素について詳細に説明するが、本発明はその要旨を超えない限り、以下に説明する範囲に何ら限定されるものではなく、そして、本発明の要旨を逸脱しない範囲で種々の変更が可能である。 These components are described in detail below, but the present invention is not limited to the scope described below as long as it does not exceed the gist of the invention, and various modifications are possible without departing from the gist of the invention.
　［ポリエステル極細繊維］
　本発明の人工皮革は、構成要素の１つである繊維質基材が、平均単繊維直径が０．１μｍ以上１０．０μｍ以下のポリエステル極細繊維で構成されてなる。なお、「ポリエステル極細繊維」とは、下記のポリエステル系樹脂からなる極細繊維のことを言い、極細繊維とは、後述の方法によって測定、算出される単繊維直径が「０．１μｍ以上１０．０μｍ以下の繊維」のことを指す。 [Polyester ultrafine fiber]
The artificial leather of the present invention is made of a fibrous base material, which is one of the components, composed of polyester ultrafine fibers having an average single fiber diameter of 0.1 μm or more and 10.0 μm or less. Note that "polyester ultrafine fibers" refers to ultrafine fibers made of a polyester resin described below, and ultrafine fibers refer to "fibers having a single fiber diameter of 0.1 μm or more and 10.0 μm or less" measured and calculated by the method described below.
　なお、この発明において、「ポリエステル系樹脂」とは、繰り返し単位に占めるポリエステル単位のモル分率が８０モル％～１００モル％である樹脂のことを指す。特記がない限り、「・・・系樹脂」との記載があるものは同様である。このポリエステル系樹脂は、耐熱性、耐光性などに優れた人工皮革とすることができ、その具体例としては、ポリエチレンテレフタレート、ポリブチレンテレフタレート、ポリトリメチレンテレフタレート、ならびに、これらのポリエステル樹脂の混合物、共重合体などが挙げられる。ポリエステル系樹脂は、例えば、ジカルボン酸および／またはそのエステル形成性誘導体とジオールとを原料として得ることができる。 In this invention, "polyester-based resin" refers to a resin in which the molar fraction of polyester units in the repeating units is 80 mol% to 100 mol%. Unless otherwise specified, the term "...-based resin" has the same meaning. This polyester-based resin can be used to make artificial leather with excellent heat resistance, light resistance, etc., and specific examples include polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and mixtures and copolymers of these polyester resins. Polyester-based resins can be obtained, for example, from dicarboxylic acids and/or their ester-forming derivatives and diols as raw materials.
　前記のポリエステル系樹脂に用いられるジカルボン酸および／またはそのエステル形成性誘導体としては、テレフタル酸、イソフタル酸、２，６－ナフタレンジカルボン酸、ジフェニル－４，４’－ジカルボン酸およびそのエステル形成性誘導体などが挙げられる。なお、本発明でいうエステル形成性誘導体とは、ジカルボン酸の低級アルキルエステル、酸無水物、アシル塩化物などである。具体的には、メチルエステル、エチルエステル、ヒドロキシエチルエステルなどが好ましく用いられる。本発明で用いられるジカルボン酸および／またはそのエステル形成性誘導体としてより好ましい態様は、テレフタル酸および／またはそのジメチルエステルである。 The dicarboxylic acid and/or its ester-forming derivative used in the polyester resin may include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, diphenyl-4,4'-dicarboxylic acid and its ester-forming derivative. The ester-forming derivative in the present invention is a lower alkyl ester of a dicarboxylic acid, an acid anhydride, an acyl chloride, etc. Specifically, methyl ester, ethyl ester, hydroxyethyl ester, etc. are preferably used. A more preferred embodiment of the dicarboxylic acid and/or its ester-forming derivative used in the present invention is terephthalic acid and/or its dimethyl ester.
　前記のポリエステル系樹脂に用いられるジオールとしては、エチレングリコール、１，３－プロパンジオール、１，４－ブタンジオール、シクロヘキサンジメタノールなどが挙げられる。中でもエチレングリコールが好ましく用いられる。 Diols used in the polyester resins include ethylene glycol, 1,3-propanediol, 1,4-butanediol, cyclohexanedimethanol, etc. Among these, ethylene glycol is preferably used.
　そして、前記のポリエステル系樹脂には、種々の目的に応じて、酸化チタン粒子等の無機粒子、潤滑剤、顔料、熱安定剤、紫外線吸収剤、導電剤、蓄熱剤および抗菌剤等を含有させることができる。 The polyester resin can contain inorganic particles such as titanium oxide particles, lubricants, pigments, heat stabilizers, UV absorbers, conductive agents, heat storage agents, antibacterial agents, etc., depending on the purpose.
　ポリエステル系樹脂に含有させることのできるポリエステル系樹脂以外の成分の含有量としては、ポリエステル系樹脂中の３質量％以下、より好ましくは１．５質量％以下とすることが好ましい。ポリエステル系樹脂以外の成分の含有量を３質量％以下とすることで、ポリエステル極細繊維の強度低下を抑制でき、耐摩耗性に優れた人工皮革とすることができる。 The content of components other than polyester resin that can be contained in polyester resin is preferably 3% by mass or less, more preferably 1.5% by mass or less. By keeping the content of components other than polyester resin to 3% by mass or less, it is possible to suppress the decrease in strength of polyester microfibers, and to produce artificial leather with excellent abrasion resistance.
　ポリエステル極細繊維の断面形状としては、丸断面、異形断面のいずれでも採用することができる。異形断面の具体例としては、楕円、扁平、三角などの多角形、扇形、十字型などが挙げられる。 The cross-sectional shape of polyester microfibers can be either round or irregular. Specific examples of irregular cross-sections include ellipses, flats, polygons such as triangles, sectors, and crosses.
　本発明において、ポリエステル極細繊維の平均単繊維直径は、０．１μｍ以上１０．０μｍ以下である。ポリエステル極細繊維の平均単繊維直径が１０．０μｍ以下、好ましくは７．０μｍ以下、より好ましくは５．０μｍ以下であることによって、人工皮革をより柔軟なものとすることができる。また、立毛の品位を向上させることができる。一方、ポリエステル極細繊維の平均単繊維直径が０．１μｍ以上、好ましくは０．３μｍ以上、より好ましくは０．７μｍ以上であることによって、染色を行う場合に染色後の発色性に優れた人工皮革とすることができる。また、バフィングによる起毛処理を行う際に、束状に存在するポリエステル極細繊維の分散しやすさ、さばけやすさを向上させることができる。 In the present invention, the average single fiber diameter of the polyester ultrafine fibers is 0.1 μm or more and 10.0 μm or less. By making the average single fiber diameter of the polyester ultrafine fibers 10.0 μm or less, preferably 7.0 μm or less, and more preferably 5.0 μm or less, the artificial leather can be made 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 polyester ultrafine fibers 0.1 μm or more, preferably 0.3 μm or more, and more preferably 0.7 μm or more, the artificial leather can have excellent color development after dyeing when dyeing. In addition, when performing the nap raising process by buffing, the ease of dispersion and handling of the polyester ultrafine fibers present in bundles can be improved.
　なお、本発明でいうポリエステル極細繊維の単繊維直径、平均単繊維直径とは、以下の方法で測定、算出されるものである。すなわち、
（１）得られた人工皮革を厚み方向に切断した断面を走査型電子顕微鏡（ＳＥＭ、例えば、株式会社キーエンス製「ＶＨＸ－Ｄ５００／Ｄ５１０」など）により倍率１０００倍で観察する。
（２）観察面内の任意の５０本のポリエステル極細繊維の単繊維直径をそれぞれのポリエステル極細繊維断面において３方向で測定する。ただし、異型断面のポリエステル極細繊維を採用した場合には、まず単繊維の断面積を測定し、当該断面積となる円の直径を以下の式で算出する。これより得られた直径をその単繊維の単繊維直径とする
　　　単繊維直径（μｍ）＝（４×（単繊維の断面積（μｍ２））／π）１／２
（３）上記のようにして得られた合計１５０点の単繊維直径の算術平均値（μｍ）を算出し、小数点以下第二位で四捨五入し、これをポリエステル極細繊維の平均単繊維直径（μｍ）とする。 The single fiber diameter and average single fiber diameter of the polyester ultrafine fiber 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 under a scanning electron microscope (SEM, for example, "VHX-D500/D510" manufactured by Keyence Corporation) at a magnification of 1000 times.
(2) The single fiber diameters of 50 random polyester ultrafine fibers within the observation area are measured in three directions on the cross section of each polyester ultrafine fiber. However, when polyester ultrafine fibers with an irregular cross section are used, the cross-sectional area of the single fiber is first measured, and the diameter of the circle with the cross-sectional area is calculated using the following formula. The diameter thus obtained is regarded as the single fiber diameter of the single fiber: Single fiber diameter (μm) = (4 × (cross-sectional area of single fiber ( μm2 )) / π) 1/2
(3) The arithmetic mean value (μm) of the single fiber diameters of the total of 150 points obtained as described above is calculated, and rounded off to one decimal place to obtain the average single fiber diameter (μm) of the polyester ultrafine fiber.
　［繊維質基材］
　本発明で用いられる繊維質基材は、前記のポリエステル極細繊維で構成されてなる。なお、繊維質基材には、異なる原料のポリエステル極細繊維が混合されていることが許容される。 [Fiber base material]
The fibrous base material used in the present invention is composed of the above-mentioned polyester ultrafine fibers. It is acceptable for the fibrous base material to contain polyester ultrafine fibers made of different raw materials.
　前記の繊維質基材の具体的な形態としては、前記のポリエステル極細繊維それぞれが絡合してなる不織布やポリエステル極細繊維の繊維束が絡合してなる不織布などを用いることができる。中でも、ポリエステル極細繊維の繊維束が絡合してなる不織布が、人工皮革の強度や風合いの観点から好ましく用いられる。柔軟性や風合いの観点から、特に好ましくは、ポリエステル極細繊維の繊維束を構成するポリエステル極細繊維同士が適度に離間して１μｍ～１００μｍの空隙を有する不織布が好ましく用いられる。このように、ポリエステル極細繊維の繊維束が絡合してなる不織布は、例えば、極細繊維発現型繊維をあらかじめ絡合した後にポリエステル極細繊維を発現させることによって得ることができる。また、ポリエステル極細繊維の繊維束を構成するポリエステル極細繊維同士が適度に離間して空隙を有する不織布は、例えば、海成分を除去することによって島成分の間に空隙を形成することができる海島型複合繊維を用いることによって得ることができる。 Specific examples of the fibrous substrate include nonwoven fabrics in which the polyester ultrafine fibers are entangled with each other and nonwoven fabrics in which fiber bundles of polyester ultrafine fibers are entangled. Among these, nonwoven fabrics in which fiber bundles of polyester ultrafine fibers are entangled are preferably used from the viewpoint of the strength and texture of the artificial leather. From the viewpoint of flexibility and texture, nonwoven fabrics in which the polyester ultrafine fibers constituting the fiber bundles of polyester ultrafine fibers are appropriately spaced apart and have gaps of 1 μm to 100 μm are particularly preferably used. In this way, nonwoven fabrics in which fiber bundles of polyester ultrafine fibers are entangled with each other can be obtained, for example, by entangling ultrafine fiber-expressing fibers in advance and then expressing polyester ultrafine fibers. In addition, nonwoven fabrics in which the polyester ultrafine fibers constituting the fiber bundles of polyester ultrafine fibers are appropriately spaced apart and have gaps can be obtained, for example, by using sea-island composite fibers in which gaps can be formed between island components by removing the sea component.
　前記の不織布としては、短繊維不織布、長繊維不織布のいずれでもよいが、人工皮革の風合いや品位の観点から短繊維不織布がより好ましく用いられる。なお、短繊維不織布とは、繊維長が専ら１０００ｍｍ未満の繊維で構成されてなる不織布を指す。 The nonwoven fabric may be either a short fiber nonwoven fabric or a long fiber nonwoven fabric, but from the viewpoint of the texture and quality of the artificial leather, a short fiber nonwoven fabric is more preferably used. Note that a short fiber nonwoven fabric refers to a nonwoven fabric composed exclusively of fibers with a fiber length of less than 1000 mm.
　短繊維不織布を用いた場合において、この短繊維不織布を構成する繊維の繊維長は、２５ｍｍ以上９０ｍｍ以下の範囲であることが好ましい。繊維長を２５ｍｍ以上、より好ましくは３５ｍｍ以上、さらに好ましくは４０ｍｍ以上とすることにより、絡合により耐摩耗性に優れた人工皮革が得られやすくなる。また、繊維長を９０ｍｍ以下、より好ましくは８０ｍｍ以下、さらに好ましくは７０ｍｍ以下とすることにより、より風合いや品位に優れた人工皮革を得ることができる。 When a short-fiber nonwoven fabric is used, the fiber length of the fibers that make up the short-fiber nonwoven fabric is preferably in the range of 25 mm or more and 90 mm or less. By making the fiber length 25 mm or more, more preferably 35 mm or more, and even more preferably 40 mm or more, it becomes easier to obtain artificial leather with excellent abrasion resistance due to entanglement. Also, by making the fiber length 90 mm or less, more preferably 80 mm or less, and even more preferably 70 mm or less, it becomes possible to obtain artificial leather with better texture and quality.
　本発明において、繊維質基材として不織布を用いる場合、強度を向上させるなどの目的で、不織布の内部に織物や編物を挿入したり、積層したり、または、裏張りしたりすることもできる。かかる織物や編物を構成する繊維の平均単繊維直径は、絡合時における損傷を抑制し、強度を維持することができるため、０．３μｍ以上１０μｍ以下であることが好ましい。 In the present invention, when a nonwoven fabric is used as the fibrous substrate, a woven or knitted fabric can be inserted, laminated, or lined inside the nonwoven fabric for the purpose of improving strength. The average single fiber diameter of the fibers constituting such a woven or knitted fabric is preferably 0.3 μm or more and 10 μm or less, since this can suppress damage during entanglement and maintain strength.
　また、前記の織物や編物を構成する繊維がマルチフィラメントである場合には、そのマルチフィラメントの総繊度は、３０ｄｔｅｘ以上１７０ｄｔｅｘ以下であることが好ましい。織物などを構成するマルチフィラメントの総繊度を１７０ｄｔｅｘ以下、より好ましくは１５０ｄｔｅｘ以下とすることにより、柔軟性に優れた人工皮革が得られる。一方、総繊度を３０ｄｔｅｘ以上とすることにより、人工皮革としての製品の形態安定性が向上するだけでなく、不織布と織物などをニードルパンチ等で絡合一体化させる際に、織物などを構成する繊維が人工皮革の表面に露出しにくくなるため好ましい。このとき、織物においては経糸と緯糸のマルチフィラメントの総繊度は同じであっても異なっていてもよい。 Furthermore, when the fibers constituting the woven or knitted fabric are multifilaments, the total fineness of the multifilaments is preferably 30 dtex or more and 170 dtex or less. By making the total fineness of the multifilaments constituting the woven fabric etc. 170 dtex or less, more preferably 150 dtex or less, an artificial leather with excellent flexibility can be obtained. On the other hand, by making the total fineness 30 dtex or more, not only does the shape stability of the product as artificial leather improve, but also when the nonwoven fabric and the woven fabric etc. are entangled and integrated by needle punching or the like, the fibers constituting the woven fabric etc. are less likely to be exposed on the surface of the artificial leather, which is preferable. In this case, the total fineness of the multifilaments of the warp threads and weft threads in the woven fabric may be the same or different.
　なお、本発明において、前記のマルチフィラメントの総繊度は、ＪＩＳ　Ｌ１０１３：２０１０「化学繊維フィラメント糸試験方法」の「８．３　繊度」の「８．３．１　正量繊度　ｂ）　Ｂ法（簡便法）」で測定、算出される値のことを指す。 In the present invention, the total fineness of the multifilament refers to the value measured and calculated according to "8.3 Fineness" of "8.3.1 Correct fineness b) Method B (simplified method)" in "8.3 Fineness" of JIS L1013:2010 "Test methods for chemical fiber filament yarns."
　前記の織物や編物を構成する繊維としては、ポリエチレンテレフタレート、ポリブチレンテレフタレート、ポリトリメチレンテレフタレート、ポリ乳酸などのポリエステルや、ポリアミド６やポリアミド６６などのポリアミド等の合成繊維、セルロース系ポリマー等の再生繊維、綿や麻等の天然繊維などを用いることができる。 The fibers constituting the woven or knitted fabrics may be synthetic fibers such as polyesters, such as polyethylene terephthalate, polybutylene terephthalate, polytrimethylene terephthalate, and polylactic acid, polyamides, such as polyamide 6 and polyamide 66, regenerated fibers, such as cellulose-based polymers, and natural fibers, such as cotton and hemp.
　本発明の人工皮革は、繊維質基材の見掛け密度が０．２５ｇ／ｃｍ３以上０．３０ｇ／ｃｍ３以下であることが好ましい。繊維質基材の見掛け密度の範囲について、その下限を０．２５ｇ／ｃｍ３以上、より好ましくは０．２６ｇ／ｃｍ３以上とすることで、人工皮革の耐摩耗性が優れたものとなる。一方、前記の範囲について、その上限を０．３０ｇ／ｃｍ３以下、より好ましくは０．２８ｇ／ｃｍ３以下とすることで、親水性基を有するポリウレタンが均一に付与され、反発感に優れた人工皮革とすることができる。本発明において、繊維質基材の見掛け密度は以下の式で算出する。
繊維質基材の見掛け密度（ｇ／ｃｍ３）＝人工皮革の見掛け密度（ｇ／ｃｍ３）×人工皮革中の繊維質基材の比率（％）
　ここで、人工皮革中の繊維質基材比率（％）とは、人工皮革のポリエステル極細繊維のみを溶剤で抽出したときに、人工皮革の質量を１００％として、抽出により減少した質量の割合を指す。 In the artificial leather of the present invention, the apparent density of the fibrous substrate is preferably 0.25 g/cm 3 or more and 0.30 g/cm 3 or less. By setting the lower limit of the apparent density range of the fibrous substrate to 0.25 g/cm 3 or more, more preferably 0.26 g/cm 3 or more, the abrasion resistance of the artificial leather is excellent. On the other hand, by setting the upper limit of the above range to 0.30 g/cm 3 or less, more preferably 0.28 g/cm 3 or less, the polyurethane having a hydrophilic group is uniformly applied, and the artificial leather has excellent resilience. In the present invention, the apparent density of the fibrous substrate is calculated by the following formula.
Apparent density of fibrous base material (g/cm 3 )=Apparent density of artificial leather (g/cm 3 )×Proportion of fibrous base material in artificial leather (%)
Here, the fibrous base material ratio (%) in the artificial leather refers to the percentage of mass reduced by extraction when only the polyester ultrafine fibers of the artificial leather are extracted with a solvent, with the mass of the artificial leather being taken as 100%.
　［親水性基を有するポリウレタン］
　次に、本発明の人工皮革は、親水性基を有するポリウレタンを構成要素として含む。以下、この詳細について、さらに説明する。 [Polyurethane having hydrophilic groups]
Next, the artificial leather of the present invention contains polyurethane having a hydrophilic group as a constituent element. The details of this will be described in further detail below.
　（１）親水性基を有するポリウレタン
　まず、本発明において「親水性基」とは、「活性水素を有する基」を指す。この活性水素を有する基の具体例としては、水酸基やカルボキシル基、スルホン酸基、アミノ基等が挙げられる。後述するカルボジイミド基を有する架橋剤との反応性の観点から、水酸基またはカルボキシル基が好ましい。 (1) Polyurethane having a hydrophilic group First, in the present invention, the "hydrophilic group" refers to a "group having active hydrogen". Specific examples of the group having active hydrogen include a hydroxyl group, a carboxyl group, a sulfonic acid group, and an amino group. From the viewpoint of reactivity with a crosslinking agent having a carbodiimide group described later, a hydroxyl group or a carboxyl group is preferred.
　親水性基を有するポリウレタンは、後述する高分子ポリオールと、有機ジイソシアネートと、親水性基を有する活性水素成分含有化合物とを反応させて親水性プレポリマーを形成し、その後に鎖伸長剤を添加・反応させて得られるポリウレタン前駆体に、架橋剤を反応させることによって得ることができる。以下に、これらについて詳細を説明する。 Polyurethanes having hydrophilic groups can be obtained by reacting a polymer polyol (described below), an organic diisocyanate, and an active hydrogen component-containing compound having a hydrophilic group to form a hydrophilic prepolymer, and then adding and reacting a chain extender to obtain a polyurethane precursor, and then reacting the polyurethane precursor with a crosslinking agent. These are explained in detail below.
　（１－１）高分子ポリオール
　本発明で好ましく用いられる高分子ポリオールとしては、ポリエーテル系ポリオール、ポリエステル系ポリオール、ポリカーボネート系ポリオール等を挙げることができる。 (1-1) Polymer Polyols Polymer polyols preferably used in the present invention include polyether polyols, polyester polyols, polycarbonate polyols, and the like.
　まず、ポリエーテル系ポリオールとしては、多価アルコールやポリアミンを開始剤として、エチレンオキシド、プロピレンオキサイド、ブチレンオキサイド、スチレンオキサイド、テトラヒドロフラン、エピクロルヒドリンおよびシクロヘキシレン等のモノマーを付加・重合して得られるポリオール、ならびに、前記のモノマーをプロトン酸、ルイス酸およびカチオン触媒等を触媒として開環重合して得られるポリオールが挙げられる。具体的には、ポリエチレングリコール、ポリプロピレングリコール、ポリテトラメチレングリコールなど、およびこれらを組み合わせた共重合ポリオールを挙げることができる。 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, as well as polyols obtained by ring-opening polymerization of the above-mentioned monomers using protonic acids, Lewis acids, cationic catalysts, and the like as catalysts. Specific examples include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, and the like, as well as copolymer polyols that combine these.
　次に、ポリエステル系ポリオールとしては、各種低分子量ポリオールと多塩基酸とを縮合させて得られるポリエステルポリオールや、ラクトンを開重合することによって得られるポリオールなどを挙げることができる。 Next, examples of polyester polyols include polyester polyols obtained by condensing various low molecular weight polyols with polybasic acids, and polyols obtained by depolymerizing lactones.
　ポリエステル系ポリオールに用いられる低分子量ポリオールとしては、例えば、「エチレングリコール、１，３－プロピレングリコール、１，４－ブタンジオール、１，５－ペンタンジオール、１，６－ヘキサンジオール、１，７－ヘプタンジオール、１．８－オクタンジオール、１，９－ノナンジオール、１，１０－デカンジオール」などの直鎖アルキレングリコールや、「ネオペンチルグリコール、３－メチル－１，５－ペンタンジオール、２，４－ジエチル－１，５－ペンタンジオール、２－メチル－１，８－オクタンジオール」などの分岐アルキレングリコール、１，４－シクロヘキサンジオールなどの脂環式ジオール、および１，４－ビス（β－ヒドロキシエトキシ）ベンゼンなどの芳香族２価アルコール、などから選ばれる１種または２種以上が挙げられる。また、ビスフェノールＡに各種アルキレンオキサイドを付加させて得られる付加物も、低分子量ポリオールとして使用可能である。 Low molecular weight polyols used in polyester polyols include, for example, 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.
　一方、ポリエステル系ポリオールに用いられる多塩基酸としては、例えば、コハク酸、マレイン酸、アジピン酸、グルタル酸、ピメリン酸、スベリン酸、アゼライン酸、セバシン酸、ドデカンジカルボン酸、フタル酸、イソフタル酸、テレフタル酸、およびヘキサヒドロイソフタル酸などからなる群から選ばれる１種または２種以上が挙げられる。 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.
　そして、ポリカーボネート系ポリオールとしては、ポリオールとジアルキルカーボネート、あるいはポリオールとジアリールカーボネートなど、ポリオールとカーボネート化合物との反応によって得られる化合物を挙げることができる。 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.
　ポリカーボネート系ポリオールに用いられるポリオールとしては、ポリエステル系ポリオールに用いられる低分子量ポリオールを用いることができる。一方、ジアルキルカーボネートとしては、ジメチルカーボネートやジエチルカーボネートなどを用いることができ、ジアリールカーボネートとしてはジフェニルカーボネートなどを用いることができる。 As the polyol used in the polycarbonate-based polyol, the low molecular weight polyol used in the polyester-based polyol can be used. On the other hand, as the dialkyl carbonate, dimethyl carbonate, diethyl carbonate, etc. can be used, and as the diaryl carbonate, diphenyl carbonate, etc. can be used.
　なお、本発明で好ましく用いられる高分子ポリオールの数平均分子量は、５００以上５０００以下であることが好ましい。高分子ポリオールの数平均分子量を５００以上、より好ましくは１５００以上とすることにより、人工皮革の風合いが硬くなるのを防ぎやすくすることができる。また、数平均分子量を５０００以下、より好ましくは４０００以下とすることにより、バインダーとしての親水性基を有するポリウレタンの強度を維持しやすくすることができる。 The number average molecular weight of the polymer polyol preferably used in the present invention is preferably 500 or more and 5000 or less. By making the number average molecular weight of the polymer polyol 500 or more, more preferably 1500 or more, it is possible to easily prevent the texture of the artificial leather from becoming hard. In addition, by making the number average molecular weight 5000 or less, more preferably 4000 or less, it is possible to easily maintain the strength of the polyurethane having hydrophilic groups as a binder.
　（１－２）有機ジイソシアネート
　本発明で用いられる有機ジイソシアネートとしては、炭素数（ＮＣＯ基中の炭素を除く、以下同様。）が６以上２０以下の芳香族ジイソシアネート、炭素数が２以上１８以下の脂肪族ジイソシアネート、炭素数が４以上１５以下の脂環式ジイソシアネート、炭素数が８以上１５以下の芳香脂肪族ジイソシアネート、これらのジイソシアネートの変性体（カーボジイミド変性体、ウレタン変性体、ウレトジオン変性体など）およびこれらの２種以上の混合物等が含まれる。 (1-2) Organic Diisocyanate Examples of the organic diisocyanate used in the present invention include aromatic diisocyanates having 6 to 20 carbon atoms (excluding carbons in NCO groups, the same applies below), 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, urethodione modified products, etc.), and mixtures of two or more of these.
　前記の炭素数が６以上２０以下の芳香族ジイソシアネートの具体例としては、１，３－および／または１，４－フェニレンジイソシアネート、２，４－および／２，６－トリレンジイソシアネート、２，４’－および／または４，４’－ジフェニルメタンジイソシアネート（以下ＭＤＩと略記）、４，４’－ジイソシアナトビフェニル、３，３’－ジメチル－４，４’－ジイソシアナトビフェニル、３，３’－ジメチル－４，４’－ジイソシアナトジフェニルメタン、および１，５－ナフチレンジイソシアネートなどが挙げられ、中でも、親水性基を有するポリウレタンとした際の柔軟性に優れる、ＭＤＩを用いることが好ましい。 Specific examples of the aromatic diisocyanate having 6 to 20 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.
　前記の炭素数が２以上１８以下の脂肪族ジイソシアネートの具体例としては、エチレンジイソシアネート、テトラメチレンジイソシアネート、ヘキサメチレンジイソシアネート、ドデカメチレンジイソシアネート、２，２，４－トリメチルヘキサメチレンジイソシアネート、リジンジイソシアネート、２，６－ジイソシアナトメチルカプロエート、ビス（２－イソシアナトエチル）カーボネート、および２－イソシアナトエチル－２，６－ジイソシアナトヘキサエートなどが挙げられる。 Specific examples of the aliphatic diisocyanates having 2 to 18 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.
　前記の炭素数が４以上１５以下の脂環式ジイソシアネートの具体例としては、イソホロンジイソシアネート、ジシクロヘキシルメタン－４，４’－ジイソシアネート、シクロヘキシレンジイソシアネート、メチルシクロヘキシレンジイソシアネート、ビス（２－イソシアナトエチル）－４－シクロヘキシレン－１，２－ジカルボキシレート、および２，５－および／または２，６－ノルボルナンジイソシアネートなどが挙げられる。中でも親水性基を有するポリウレタンとした際の耐久性に優れる、ジシクロヘキシルメタン－４，４’－ジイソシアネートを用いることが好ましい。 Specific examples of the alicyclic diisocyanates 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. Among these, it is preferable to use dicyclohexylmethane-4,4'-diisocyanate, which has excellent durability when made into a polyurethane having a hydrophilic group.
　前記の炭素数が８以上１５以下の芳香脂肪族ジイソシアネートの具体例としては、ｍ－および／またはｐ－キシリレンジイソシアネートや、α、α、α’、α’－テトラメチルキシリレンジイソシアネートなどが挙げられる。 Specific examples of aromatic aliphatic diisocyanates having 8 to 15 carbon atoms include m- and/or p-xylylene diisocyanate and α,α,α',α'-tetramethylxylylene diisocyanate.
　（１－３）親水性基を有する活性水素成分含有化合物
　本発明で好ましく用いられる親水性基を有する活性水素成分含有化合物としては、ノニオン性基、アニオン性基およびカチオン性基から選ばれる一つ以上の基と活性水素とを含有する化合物等が挙げられる。これらの活性水素成分含有化合物は、中和剤で中和した塩の状態で用いることもできる。この親水性基を有する活性水素成分含有化合物を用いることによって、後述の人工皮革の製造方法で用いられる水分散液の安定性を高めることができる。 (1-3) Active hydrogen component-containing compound having hydrophilic group The active hydrogen component-containing compound having a hydrophilic group that is preferably used in the present invention includes compounds containing active hydrogen and one or more 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. By using this active hydrogen component-containing compound having a hydrophilic group, the stability of the aqueous dispersion used in the manufacturing method of the artificial leather described below can be improved.
　ノニオン性基と活性水素を有する化合物としては、２つ以上の活性水素成分または２つ以上のイソシアネート基を含み、側鎖に分子量２５０～９０００のポリオキシエチレングリコール基等を有している化合物、および、トリメチロールプロパンやトリメチロールブタン等のトリオール等が挙げられる。 Examples of compounds that have a nonionic group and active hydrogen include compounds that contain two or more active hydrogen components or two or more isocyanate groups and have polyoxyethylene glycol groups with a molecular weight of 250 to 9000 on the side chain, and triols such as trimethylolpropane and trimethylolbutane.
　アニオン性基と活性水素を有する化合物としては、２，２－ジメチロールプロピオン酸、２，２－ジメチロールブタン酸、２，２－ジメチロール吉草酸等のカルボキシル基含有化合物およびそれらの誘導体や、１，３－フェニレンジアミン－４，６－ジスルホン酸、３－（２，３－ジヒドロキシプロポキシ）－１－プロパンスルホン酸等のスルホン酸基を含有する化合物およびそれらの誘導体、並びにこれらの化合物を中和剤で中和した塩が挙げられる。 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 their derivatives; sulfonic acid group-containing compounds such as 1,3-phenylenediamine-4,6-disulfonic acid and 3-(2,3-dihydroxypropoxy)-1-propanesulfonic acid, and their derivatives; and salts of these compounds neutralized with a neutralizing agent.
　カチオン性基と活性水素を含有する化合物としては、３－ジメチルアミノプロパノール、Ｎ－メチルジエタノールアミン、Ｎ－プロピルジエタノールアミン等の３級アミノ基含有化合物およびそれらの誘導体が挙げられる。 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, as well as their derivatives.
　（１－４）鎖伸長剤
　本発明に用いられる鎖伸長剤としては、水、「エチレングリコール、プロピレングリコール、１，３－ブチレングリコール、１，４－ブタンジオール、１，６－ヘキサンジオール、ジエチレングリコールおよびネオペンチルグリコールなど」の低分子ジオール、「１，４－ビス（ヒドロキシメチル）シクロヘキサンなど」の脂環式ジオール、「１，４－ビス（ヒドロキシエチル）ベンゼンなど」の芳香族ジオール、「エチレンジアミンなど」の脂肪族ジアミン、「イソホロンジアミンなど」の脂環式ジアミン、「４，４－ジアミノジフェニルメタンなど」の芳香族ジアミン、「キシレンジアミンなど」の芳香脂肪族ジアミン、「エタノールアミンなど」のアルカノールアミン、ヒドラジン、「アジピン酸ジヒドラジドなど」のジヒドラジド、および、これらの２種以上の混合物が挙げられる。 (1-4) 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 "xylylenediamine," alkanolamines such as "ethanolamine," hydrazine, dihydrazides such as "adipic acid dihydrazide," and mixtures of two or more of these.
　これらのうち好ましい鎖伸長剤は、水、低分子ジオールおよび芳香族ジアミンから選ばれたものであり、さらに好ましくは水、エチレングリコール、１，４－ブタンジオール、４，４’－ジアミノジフェニルメタンおよびこれらの２種以上の混合物から選ばれたものである。 Among these, preferred chain extenders are those selected from water, low molecular weight diols and aromatic diamines, and more preferably those selected from water, ethylene glycol, 1,4-butanediol, 4,4'-diaminodiphenylmethane and mixtures of two or more of these.
　（１－５）ポリウレタン前駆体の構成
　前記のとおり、本発明で用いられるポリウレタン前駆体は、前記の高分子ポリオールと、有機ジイソシアネートと、親水性基を有する活性水素成分含有化合物とを反応させて親水性プレポリマーを形成し、その後に鎖伸長剤を添加・反応させることによって調製される。 (1-5) Constitution of Polyurethane Precursor As described above, the polyurethane precursor used in the present invention is prepared by reacting the above-mentioned high molecular weight 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.
　（１－６）架橋剤
　本発明に用いられる架橋剤としては、ポリウレタン前駆体に導入された反応性基と反応し得る反応性基を、分子内に２個以上有するものを使用することができる。具体的には、水溶性イソシアネート化合物やブロックイソシアネート化合物等のポリイソシアネート系架橋剤、メラミン系架橋剤、カルボジイミド系架橋剤等が挙げられる。架橋剤は、１種を単独で用いてもよく２種以上を併用することもできる。 (1-6) 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. Specific examples include polyisocyanate-based crosslinking agents such as water-soluble isocyanate compounds and blocked isocyanate compounds, melamine-based crosslinking agents, and carbodiimide-based crosslinking agents. The crosslinking agents may be used alone or in combination of two or more.
　水溶性イソシアネート系化合物は、分子内にイソシアネート基を２個以上有するものであり、前記の有機ジイソシアネート化合物等が挙げられる。市販品としては、バイエルマテリアルサイエンス株式会社製「バイヒジュール」（登録商標）シリーズ、および、「デスモジュール」（登録商標）シリーズ等が挙げられる。 Water-soluble isocyanate compounds have two or more isocyanate groups in the molecule, and examples of such compounds include the organic diisocyanate compounds mentioned above. Commercially available products include the "Bayhydur" (registered trademark) series and the "Desmodur" (registered trademark) series manufactured by Bayer MaterialScience Co., Ltd.
　ブロックイソシアネート系化合物は、分子内にブロックイソシアネート基を２個以上有するものである。ブロックイソシアネート基は、前記の有機ポリイソシアネート化合物をアミン類やフェノール類やイミン類やメルカプタン類や、ピラゾール類やオキシム類や活性メチレン類等のブロック化剤によりブロックしたものを意味する。これらの市販品としては、第一工業製薬株式会社の「エラストロン」（登録商標）シリーズ、旭化成株式会社製の「デュラネート」（登録商標）シリーズおよび三井化学株式会社製の「タケネート」（登録商標）シリーズ等が挙げられる。 A blocked isocyanate compound has two or more blocked isocyanate groups in the molecule. A blocked isocyanate group refers to an organic polyisocyanate compound that has been blocked with a blocking agent such as amines, phenols, imines, mercaptans, pyrazoles, oximes, or active methylenes. Commercially available products include the "Elastron" (registered trademark) series from Daiichi Kogyo Seiyaku Co., Ltd., the "Duranate" (registered trademark) series from Asahi Kasei Corporation, and the "Takenate" (registered trademark) series from Mitsui Chemicals, Inc.
　オキサゾリン系架橋剤としては、分子内にオキサゾリン基（オキサゾリン骨格）を２個以上有する化合物が挙げられる。市販品としては、株式会社日本触媒製「エポクロス」（登録商標）シリーズ等が挙げられる。 Oxazoline-based crosslinking agents include compounds that have 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.
　カルボジイミド系架橋剤としては、分子内にカルボジイミド基を２個以上有する化合物が挙げられる。その市販品としては、日清紡ケミカル株式会社製「カルボジライト」（登録商標）シリーズ等が挙げられる。 Carbodiimide crosslinking agents include compounds that have two or more carbodiimide groups in the molecule. Commercially available products include the "Carbodilite" (registered trademark) series manufactured by Nisshinbo Chemical Inc.
　これらの中でも、反応後に得られる親水性基を有するポリウレタンの耐久性および柔軟性に特に優れることから、カルボジイミド系架橋剤を用いることが特に好ましい。 Among these, it is particularly preferable to use a carbodiimide-based crosslinking agent, since the polyurethane having hydrophilic groups obtained after the reaction has particularly excellent durability and flexibility.
　（１－７）親水性基を有するポリウレタンの構成
　親水性基を有するポリウレタンは、柔軟性の観点から、ポリエーテル系ポリオールに由来する構成成分を含むことが好ましい。親水性基を有するポリウレタンがポリエーテル系ポリオールに由来する構成成分を含むことによって、そのエーテル結合の自由度が高いことでガラス転移温度が低く、且つ凝集力も弱い為に柔軟性に優れる水分散型ポリウレタンとすることができる。 (1-7) Constitution of polyurethane having hydrophilic group From the viewpoint of flexibility, the polyurethane having hydrophilic group preferably contains a constituent component derived from polyether-based polyol. By containing a constituent component derived from polyether-based polyol in the polyurethane having hydrophilic group, the degree of freedom of the ether bond is high, so that the glass transition temperature is low and the cohesive force is weak, so that the water-dispersible polyurethane having excellent flexibility can be obtained.
　また、親水性基を有するポリウレタンは、その耐久性の観点から、さらにポリカーボネート系ポリオールに由来する構成成分を含むことが好ましい。親水性基を有するポリウレタンがポリカーボネート系ポリオールに由来する構成成分を含むことによって、そのカーボネート基の有する高い凝集力により、耐水性、耐熱性、耐候性、力学物性に優れる、親水性基を有するポリウレタンとすることができる。 In addition, from the viewpoint of durability, it is preferable that the polyurethane having hydrophilic groups further contains a component derived from a polycarbonate-based polyol. By containing a component derived from a polycarbonate-based polyol in the polyurethane having hydrophilic groups, it is possible to obtain a polyurethane having hydrophilic groups that has excellent water resistance, heat resistance, weather resistance, and mechanical properties due to the high cohesive force of the carbonate groups.
　なお、親水性基を有するポリウレタンの構成成分を確認する方法としては、人工皮革から人工皮革を構成するポリエステル極細繊維を溶出し、不溶物（親水性基を有するポリウレタン）について、赤外分光分析（分析機器としては、例えば、日本分光株式会社製「ＦＴ／ＩＲ　４０００　ｓｅｒｉｅｓ」など）、および熱分解ＧＣ／ＭＳ分析（分析機器としては、例えば、株式会社島津製作所製「ＧＣＭＳ－ＱＰ５０５０Ａ」など）を分析することにより、親水性基を有するポリウレタンがポリエステルポリオールに由来する構成成分やポリカーボネートポリオールに由来する構成成分を含むことを確認することが可能である。なお、人工皮革を構成するポリエステル極細繊維を溶出可能な溶剤としては、ｍ－クレゾールやヘキサフルオロイソプロパノールを用いることができるが、室温で取り扱い可能なヘキサフルオロイソプロパノールを用いることが好ましい。 The method for confirming the components of polyurethane having hydrophilic groups is to dissolve the polyester ultrafine fibers that make up the artificial leather from the artificial leather and analyze the insoluble matter (polyurethane having hydrophilic groups) by infrared spectroscopy (analytical equipment such as the FT/IR 4000 series manufactured by JASCO Corporation) and pyrolysis GC/MS analysis (analytical equipment such as the GCMS-QP5050A manufactured by Shimadzu Corporation), thereby making it possible to confirm that the polyurethane having hydrophilic groups contains components derived from polyester polyol and components derived from polycarbonate polyol. As a solvent capable of dissolving the polyester ultrafine fibers that make up the artificial leather, m-cresol and hexafluoroisopropanol can be used, but it is preferable to use hexafluoroisopropanol, which can be handled at room temperature.
　また、本発明で用いられる親水性基を有するポリウレタンは、N－アシルウレア結合および／またはイソウレア結合を有することが好ましい。N－アシルウレア結合および／またはイソウレア結合は前記の親水性基とカルボジイミド基を有する架橋剤の反応により形成され、親水性基を有するポリウレタン中に架橋構造を形成することで、親水性基を有するポリウレタンの耐久性を高めることができる。 In addition, 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 increased.
　なお、親水性基を有するポリウレタンに上記のＮ－アシルウレア基やイソウレア基が存在することは、人工皮革の断面に対して、例えば、飛行時間型二次イオン質量分析（ＴＯＦ－ＳＩＭＳ分析）等のマッピング処理（分析機器としては、例えば、ＩＯＮ－ＴＯＦ社製「ＴＯＦ．ＳＩＭＳ　５」など）や赤外分光分析（分析機器としては、例えば、日本分光株式会社製「ＦＴ／ＩＲ　４０００　ｓｅｒｉｅｓ」など）を行えば分析可能である。 The presence of the above-mentioned N-acylurea groups and isourea groups in polyurethanes having hydrophilic groups can be analyzed by performing a mapping process such as time-of-flight secondary ion mass spectrometry (TOF-SIMS analysis) on a cross section of the artificial leather (analytical equipment such as the TOF.SIMS 5 manufactured by ION-TOF, Inc.) or infrared spectroscopy (analytical equipment such as the FT/IR 4000 series manufactured by JASCO Corporation).
　［人工皮革］
　本発明の人工皮革は、前記の繊維質基材と、前記の親水性基を有するポリウレタンと、を構成要素として含む人工皮革である。そして、本発明の人工皮革は、前記の人工皮革における前記親水性基を有するポリウレタンの含有割合が１５質量％以上２５質量％以下であって、前記人工皮革を２５℃のＮ，Ｎ－ジメチルホルムアミドに２４時間浸漬させた後の前記の親水性基を有するポリウレタンの質量保持率が５０質量%以上８０質量%以下であり、前記人工皮革を２５℃のＮ，Ｎ－ジメチルホルムアミドに２４時間浸漬させた後に該Ｎ，Ｎ－ジメチルホルムアミド中に溶解している成分の重量平均分子量が５００００以上１０００００以下である。この３つの条件の全てを満たすことによって、初めて柔軟な風合いと、極めて負荷の高い摩耗試験を行ったとしても破断や、穴あき、ピリングなどの外観変化が起こることの少ない人工皮革とすることができるのである。 [Artificial leather]
The artificial leather of the present invention is an artificial leather containing the fibrous base material and the polyurethane having a hydrophilic group as components. The content of the polyurethane having a hydrophilic group in the artificial leather is 15% by mass or more and 25% by mass or less, the mass retention of the polyurethane having a hydrophilic group after the artificial leather is immersed in N,N-dimethylformamide at 25° C. for 24 hours is 50% by mass or more and 80% by mass or less, and the weight average molecular weight of the component dissolved in N,N-dimethylformamide after the artificial leather is immersed in N,N-dimethylformamide at 25° C. for 24 hours is 50,000 or more and 100,000 or less. Only by satisfying all of these three conditions can an artificial leather be obtained that has a soft texture and is less susceptible to changes in appearance such as breakage, holes, and pilling even when subjected to a highly loaded abrasion test.
　まず、本発明の人工皮革は、親水性基を有するポリウレタンの含有割合が１５質量％以上２５質量％以下である。親水性基を有するポリウレタンの含有割合を１５質量％以上、好ましくは１８質量％以上とすることで、耐摩耗性の優れた人工皮革となる。一方、含有割合を２５質量％以下、好ましくは２２質量％以下とすることで、風合いの柔軟な人工皮革とすることができる。 First, the artificial leather of the present invention has a content of polyurethane having hydrophilic groups of 15% by mass or more and 25% by mass or less. By making the content of polyurethane having hydrophilic groups 15% by mass or more, preferably 18% by mass or more, the artificial leather has excellent abrasion resistance. On the other hand, by making the content 25% by mass or less, preferably 22% by mass or less, the artificial leather has a soft feel.
　本発明において、親水性基を有するポリウレタンの含有割合は以下の方法で測定、算出されるものである。すなわち、
（１）人工皮革から５ｃｍ×５ｃｍの試験片を切り出し、その試験片の質量（ＭＸ）を測定する。
（２）その試験片をヘキサフルオロイソプロパノールに浸漬させることで、人工皮革からポリエステル極細繊維を溶出する。
（３）（２）の不溶成分（親水性基を有するポリウレタン）を１００℃の乾燥機で乾燥し、質量（ＭＡ）を測定し、人工皮革中の親水性基を有するポリウレタンの含有割合を以下の式で算出する。
親水性基を有するポリウレタンの含有割合（％）＝（ＭＡ／ＭＸ）×１００。 In the present invention, the content of the polyurethane having a hydrophilic group is measured and calculated by the following method.
(1) A test piece measuring 5 cm x 5 cm is cut out from the artificial leather, and the mass (M x ) of the test piece is measured.
(2) The test piece is immersed in hexafluoroisopropanol to dissolve the polyester ultrafine fibers from the artificial leather.
(3) The insoluble component (polyurethane having hydrophilic groups) of (2) is dried in a dryer at 100° C., the mass (M A ) is measured, and the content of polyurethane having hydrophilic groups in the artificial leather is calculated using the following formula.
Content (%) of polyurethane having hydrophilic group=(M A /M X )×100.
　また、本発明の人工皮革は、前記の人工皮革を２５℃のＮ，Ｎ－ジメチルホルムアミドに２４時間浸漬させた後の前記親水性基を有するポリウレタンの質量保持率（以降、これを単に「親水性基を有するポリウレタンの質量保持率」と略記する場合がある）が５０質量%以上８０質量%以下である。親水性基を有するポリウレタンの質量保持率は、親水性基を有するポリウレタンの耐久性および柔軟性と相関がある。その下限が５０質量％以上、好ましくは５５質量％以上、さらに好ましくは６０質量％以上であると、親水性基を有するポリウレタンのうち、Ｎ，Ｎ－ジメチルホルムアミドに溶解しない、高分子量で耐久性に優れる成分によって、耐摩耗性をはじめとする耐久性に優れた人工皮革となる。一方、親水性基を有するポリウレタンの質量保持率の上限が８０質量％以下、好ましくは７５質量％以下、さらに好ましくは７０質量％以下であると、親水性基を有するポリウレタンのうち、Ｎ，Ｎ－ジメチルホルムアミドに溶解する、低分子量で風合いに優れる成分によって人工皮革の風合いが柔軟で優れるものとなる。 Furthermore, the artificial leather of the present invention has a mass retention rate of the polyurethane having hydrophilic groups (hereinafter, sometimes simply abbreviated as "mass retention rate of polyurethane having hydrophilic groups") of 50% by mass or more and 80% by mass or less after the artificial leather is immersed in N,N-dimethylformamide at 25°C for 24 hours. The mass retention rate of polyurethane having hydrophilic groups correlates with the durability and flexibility of polyurethane having hydrophilic groups. When the lower limit is 50% by mass or more, preferably 55% by mass or more, and more preferably 60% by mass or more, the artificial leather has excellent durability, including abrasion resistance, due to the high molecular weight and durable components of the polyurethane having hydrophilic groups that are insoluble in N,N-dimethylformamide. On the other hand, when the upper limit of the mass retention rate of polyurethane having hydrophilic groups is 80% by mass or less, preferably 75% by mass or less, and more preferably 70% by mass or less, the artificial leather has a soft and excellent texture due to the low molecular weight and texture-excellent components of the polyurethane having hydrophilic groups that are soluble in N,N-dimethylformamide.
　なお、本発明において、前記の親水性基を有するポリウレタンの質量保持率とは、以下の方法で測定、算出されるものである。すなわち、
（１）人工皮革から５ｃｍ×５ｃｍの試験片を切り出す。
（２）試験片をヘキサフルオロイソプロパノールに浸漬させることで、人工皮革からポリエステル極細繊維を溶出する。
（３）（２）の不溶成分（親水性基を有するポリウレタン）を１００℃の乾燥機で乾燥し、質量（Mα）を測定した後に、２５℃のＮ，Ｎ－ジメチルホルムアミドに２４時間浸漬し、不溶成分を１００℃の乾燥機で乾燥した後に質量（Mβ）を測定し、Ｎ，Ｎ－ジメチルホルムアミドに２４時間浸漬後の質量保持率を以下の式で算出する。
Ｎ，Ｎ－ジメチルホルムアミドに２４時間浸漬させた後の質量保持率（％）＝（Mβ／Mα）×１００
（４）測定は３回行い、得られた値の算術平均値（％）を算出し、小数点以下第二位で四捨五入する。 In the present invention, the mass retention of the hydrophilic group-containing polyurethane is measured and calculated by the following method.
(1) A test piece measuring 5 cm x 5 cm is cut out from the artificial leather.
(2) The test piece is immersed in hexafluoroisopropanol to dissolve the polyester ultrafine fibers from the artificial leather.
(3) The insoluble component (polyurethane having hydrophilic groups) of (2) is dried in a dryer at 100°C, and its mass (M α ) is measured. The insoluble component is then immersed in N,N-dimethylformamide at 25°C for 24 hours. The insoluble component is then dried in a dryer at 100°C, and its mass (M β ) is measured. The mass retention after immersion in N,N-dimethylformamide for 24 hours is calculated using the following formula:
Mass retention after immersion in N,N-dimethylformamide for 24 hours (%) = (M β /M α ) × 100
(4) The measurement is performed three times, and the arithmetic mean value (%) obtained is calculated and rounded off to one decimal place.
　また、前記の親水性基を有するポリウレタンの質量保持率は、使用する親水性基を有するポリウレタンの重量平均分子量や架橋度によって調整することができる。例えば、親水性基を有するポリウレタンの重量平均分子量は使用するポリウレタン前駆体の重量平均分子量や加熱処理の雰囲気温度、処理時間によって調整することができる。重量平均分子量を大きくしていくと、質量保持率は大きくなる傾向にあり、親水性基を有するポリウレタンの架橋度を高くしていくと、質量保持率は大きくなる傾向にある。 The mass retention of the polyurethane having hydrophilic groups can be adjusted by the weight average molecular weight and degree of crosslinking of the polyurethane having hydrophilic groups used. For example, the weight average molecular weight of the polyurethane having hydrophilic groups can be adjusted by the weight average molecular weight of the polyurethane precursor used, the atmospheric temperature of the heat treatment, and the treatment time. The mass retention tends to increase as the weight average molecular weight increases, and the mass retention tends to increase as the degree of crosslinking of the polyurethane having hydrophilic groups increases.
　そして、本発明の人工皮革は、前記の人工皮革を２５℃のＮ，Ｎ－ジメチルホルムアミドに２４時間浸漬させた後に該Ｎ，Ｎ－ジメチルホルムアミド中に溶解している成分の重量平均分子量（以降、これを単に「溶解成分の重量平均分子量」と略記する場合がある。）が５００００以上１０００００以下である。溶解成分は、人工皮革の構成要素である親水性基を有するポリウレタンのうち、比較的分子量の低い成分であり、この「溶解成分の重量平均分子量」は、実質的には、人工皮革の構成要素である親水性基を有するポリウレタンを得るのに用いられたポリウレタン前駆体の重量平均分子量に相当する。溶解成分の重量平均分子量の範囲について、その下限が５００００以上、より好ましくは６００００以上であることによって、親水性基を有するポリウレタンの強度、耐久性を高めることができる。一方、前記の範囲について、その上限が１０００００以下、より好ましくは９００００以下、さらに好ましくは８００００以下とすることによって、風合いの柔軟な人工皮革とすることができる。 The artificial leather of the present invention has a weight average molecular weight of 50,000 or more and 100,000 or less of components dissolved in N,N-dimethylformamide after immersing the artificial leather in N,N-dimethylformamide at 25°C for 24 hours (hereinafter, this may be abbreviated simply as "weight average molecular weight of dissolved components"). The dissolved components are components with relatively low molecular weights among polyurethanes having hydrophilic groups, which are components of artificial leather, and this "weight average molecular weight of dissolved components" essentially corresponds to the weight average molecular weight of the polyurethane precursor used to obtain polyurethanes having hydrophilic groups, which are components of artificial leather. By setting the lower limit of the range of the weight average molecular weight of the dissolved components to 50,000 or more, more preferably 60,000 or more, the strength and durability of the polyurethanes having hydrophilic groups can be increased. On the other hand, by setting the upper limit of the range to 100,000 or less, more preferably 90,000 or less, and even more preferably 80,000 or less, the artificial leather can have a soft feel.
　なお、本発明において、前記の溶解成分の重量平均分子量とは、人工皮革を２５℃のＮ，Ｎ－ジメチルホルムアミドに２４時間浸漬させた後にＮ，Ｎ－ジメチルホルムアミドに溶解している成分を乾燥させた後に、ゲルパーミエーションクロマトグラフィー（ＧＰＣ）により求めることができ、次の条件で測定される。
・機器：　例えば、東ソー株式会社製「ＨＬＣ－８２２０」など
・カラム：　例えば、東ソー株式会社製「ＴＳＫｇｅｌ　α－Ｍ」など
・溶媒：　Ｎ，Ｎ－ジメチルホルムアミド（ＤＭＦ）
・温度：　４０℃
・校正用標準試料：　ポリスチレン（例えば、東ソー株式会社製「ＴＳＫ　ｓｔａｎｄａｒｄ　ＰＯＬＹＳＴＹＲＥＮＥ」など。 In the present invention, the weight average molecular weight of the dissolved component can be determined by immersing an artificial leather in N,N-dimethylformamide at 25° C. for 24 hours, drying the components dissolved in the N,N-dimethylformamide, and then subjecting the resultant to gel permeation chromatography (GPC), and is measured under the following conditions:
Equipment: For example, "HLC-8220" manufactured by Tosoh Corporation Column: For example, "TSKgel α-M" manufactured by Tosoh Corporation Solvent: N,N-dimethylformamide (DMF)
Temperature: 40°C
Calibration standard sample: Polystyrene (e.g., "TSK standard POLYSTYRENE" manufactured by Tosoh Corporation, etc.
　また、前記の溶解成分の重量平均分子量は、用いる親水性基を有するポリウレタンの重量平均分子量および熱処理の雰囲気温度、熱処理時間によって調整することができる。 The weight average molecular weight of the soluble component can be adjusted by the weight average molecular weight of the polyurethane having a hydrophilic group used, the atmospheric temperature of the heat treatment, and the heat treatment time.
　本発明の人工皮革は、人工皮革の見掛け密度が０．３０ｇ／ｃｍ３以上０．４０ｇ／ｃｍ３以下であることが好ましい。人工皮革の見掛け密度を０．３０ｇ／ｃｍ３以上、より好ましくは０．３２ｇ／ｃｍ３以上、さらに好ましくは０．３４ｇ／ｃｍ３以上とすることで、人工皮革の耐摩耗性が優れたものとなる。一方、０．４０ｇ／ｃｍ３以下、好ましくは０．３８ｇ／ｃｍ３以下とすることで、風合いの柔軟な人工皮革とすることができる。 The artificial leather of the present invention preferably has an apparent density of 0.30 g/ cm3 or more and 0.40 g/ cm3 or less. By making the apparent density of the artificial leather 0.30 g/ cm3 or more, more preferably 0.32 g/ cm3 or more, and even more preferably 0.34 g/ cm3 or more, the abrasion resistance of the artificial leather becomes excellent. On the other hand, by making the apparent density 0.40 g/ cm3 or less, preferably 0.38 g/ cm3 or less, the artificial leather can have a soft feel.
　なお、本発明において、人工皮革の見掛け密度は、ＪＩＳ　Ｌ１９１３：２０１０「一般不織布試験方法」６．１．1（厚さ　A法）および６．２（単位面積当たりの質量）で規定される方法を用いて人工皮革の厚みおよび単位面積当たりの質量を測定し、下記の式を用いて算出される。
人工皮革の見掛け密度（ｇ／ｃｍ３）＝人工皮革の単位面積当たりの質量（ｇ／ｃｍ２）／人工皮革の厚み（ｃｍ）。 In the present invention, the apparent density of the artificial leather is calculated by measuring the thickness and mass per unit area of the artificial leather using the methods specified in JIS L1913:2010 "Testing methods for general nonwoven fabrics" 6.1.1 (thickness, method A) and 6.2 (mass per unit area), and using the following formula.
Apparent density of artificial leather (g/cm 3 )=mass per unit area of artificial leather (g/cm 2 )/thickness of artificial leather (cm).
　本発明の人工皮革は、少なくとも一方の表面に１５０μm以上４００μm以下の立毛を有することが好ましい。この立毛について、その長さ（以降、単に「立毛長」と略記することがある。）が１５０μｍ以上、好ましくは２００μｍ以上であることで、スエード調の優美な外観を有する人工皮革とすることができる。一方で、立毛長を４００μｍ以下、好ましくは３５０μｍ以下とすることで、立毛の内部への汚れの入り込みを抑制することができ、長期間の実使用時にも汚染の少なく、外観の優れる人工皮革とすることができる。 The artificial leather of the present invention preferably has nap of 150 μm or more and 400 μm or less on at least one surface. By making the length of this nap (hereinafter sometimes simply abbreviated as "napped length") 150 μm or more, preferably 200 μm or more, the artificial leather can have an elegant suede-like appearance. On the other hand, by making the nap length 400 μm or less, preferably 350 μm or less, it is possible to prevent dirt from getting into the nap, and the artificial leather can have a good appearance with less contamination even during long-term practical use.
　人工皮革が立毛を有するものである場合において、前記の立毛長は、以下の方法により算出されるものとする。
（１）リントブラシ等を用いて、前記の立毛を逆立てた状態で人工皮革の断面を走査型電子顕微鏡（ＳＥＭ、例えば、株式会社キーエンス製「ＶＨＸ－Ｄ５００／Ｄ５１０」など）により倍率５０～１００倍で撮影する。
（２）撮影したＳＥＭ画像において、図１に示す人工皮革の断面の模式図に従って、人工皮革の底面（図１中ＬＢ）に対して平行な線（図１中ＬＡ）上に２００μｍ間隔で１０本の垂線を引く。
（３）立毛部（図中１）とその立毛部以外の部分である基体部（図中２）の境界線（Ｌ０）と上記の垂線の交点上に点Ｐ１～Ｐ１０をマークする。
（４）点Ｐ１～Ｐ１０を通るそれぞれの垂線と、立毛層の先端とが交わる点Ｑ１～Ｑ１０をマークする。
（５）点Ｐ１とＱ１の距離Ｒ１とする。同様にＲ２～Ｒ１０を求め、Ｒ１～Ｒ１０の平均値（算術平均）を算出し、本発明における立毛長とする。 In the case where the artificial leather has nap, the nap length is calculated by the following method.
(1) Using a lint brush or the like, the above-mentioned nap is raised, and a cross section of the artificial leather is photographed at a magnification of 50 to 100 times using a scanning electron microscope (SEM, for example, "VHX-D500/D510" manufactured by Keyence Corporation).
(2) In the SEM image taken, ten perpendicular lines are drawn at 200 μm intervals on a line ( LA in FIG. 1) parallel to the bottom surface ( LB in FIG. 1) of the artificial leather, according to the schematic diagram of the cross section of the artificial leather shown in FIG. 1.
(3) Points P 1 to P 10 are marked on the intersections of the boundary line (L 0 ) between the napped portion (1 in the drawing) and the base portion (2 in the drawing), which is the portion other than the napped portion, and the perpendicular line.
(4) Points Q 1 to Q 10 where the perpendicular lines passing through points P 1 to P 10 intersect with the tips of the napped layers are marked.
(5) The distance between points P1 and Q1 is defined as R1 . Similarly, R2 to R10 are determined, and the average value (arithmetic mean) of R1 to R10 is calculated, which is defined as the nap length in the present invention.
　本発明の人工皮革は、ＪＩＳ　Ｌ１０９６：２００５「織物および編物の生地試験方法」の「８．１９　摩耗強さおよび摩擦変色性」の「８．１９．５　Ｅ法（マーチンデール法）」で規定されるマーチンデール摩耗試験において、摩耗回数５万回で測定した際の摩耗減量が３０ｍｇ以下であることが好ましい。摩耗減量は、人工皮革の外観の劣化を抑制できる観点から２５ｍｇ以下であることがより好ましい。 The artificial leather of the present invention preferably has an abrasion loss of 30 mg or less when measured after 50,000 abrasion cycles in the Martindale abrasion test specified in "8.19 Abrasion resistance and discoloration due to friction" of JIS L1096:2005 "Testing methods for woven and knitted fabrics" under "8.19.5 Method E (Martindale method)". From the viewpoint of suppressing deterioration of the appearance of the artificial leather, it is more preferable that the abrasion loss is 25 mg or less.
　なお、前記の摩耗減量は、人工皮革における前記親水性基を有するポリウレタンの含有割合、人工皮革を２５℃のＮ，Ｎ－ジメチルホルムアミドに２４時間浸漬させた後の前記親水性基を有するポリウレタンの質量保持率および極細繊維発現型繊維からなる不織布の絡合前後での密度変化率を記載の好ましい範囲とすることによって調整することができる。 The abrasion loss can be adjusted by adjusting the content of the polyurethane having hydrophilic groups in the artificial leather, the mass retention of the polyurethane having hydrophilic groups after immersing the artificial leather in N,N-dimethylformamide at 25°C for 24 hours, and the density change rate before and after entanglement of the nonwoven fabric made of ultrafine fiber-developing fibers within the preferred ranges described above.
　本発明により得られる人工皮革は、家具、椅子および壁材や、自動車、電車および航空機などの車輛室内における座席、天井および内装などの表皮材として非常に優美な外観を有する内装材；シャツ、ジャケット、カジュアルシューズ、スポーツシューズ、紳士靴および婦人靴等の靴のアッパー、トリム等、鞄、ベルト、財布等、およびそれらの一部に使用される衣料用資材；ワイピングクロス、研磨布およびＣＤカーテン等の工業用資材として好適に用いることができる。 The artificial leather obtained by the present invention can be suitably used as an interior material with a very elegant appearance as a surface material for furniture, chairs, and wall materials, and for seats, ceilings, and interiors in vehicle cabins such as automobiles, trains, and aircraft; as clothing materials used for uppers and trims of shoes such as shirts, jackets, casual shoes, sports shoes, men's shoes, and women's shoes, as well as bags, belts, wallets, and the like, and as parts of these; and as industrial materials such as wiping cloths, polishing cloths, and CD curtains.
　［人工皮革の製造方法］
　本発明の人工皮革の製造方法は、好ましくは、下記（１）～（４）の工程をこの順に含む、人工皮革の製造方法である。
（１）極細繊維発現型繊維からなる不織布に、絡合前後での密度変化率が２．５倍以上３．５倍以下となるように絡合処理を施し、繊維質基材を形成する工程；
（２）前記繊維質基材に、重量平均分子量が５００００以上１０００００以下のポリウレタン前駆体と、架橋剤とを含有する水分散液を含浸せしめ、次いで、加熱乾燥処理を行って繊維質基材と親水性基を有するポリウレタンと、を構成要素として含む、含浸シートを形成する工程；
（３）前記含浸シートの極細繊維発現型繊維からポリエステル極細繊維を発現させ、ポリエステル極細繊維で構成されてなる繊維質基材と、親水性基を有するポリウレタンと、を構成要素として含む熱処理前シートを形成する工程；
（４）前記熱処理前シートを、１５０℃以上２００℃以下の雰囲気温度で、５分以上２０分以下、熱処理を行う工程。 [Manufacturing method of artificial leather]
The method for producing an artificial leather of the present invention preferably includes the following steps (1) to (4) in this order:
(1) A step of forming a fibrous base material by subjecting a nonwoven fabric made of ultrafine fiber-developing fibers to an entanglement treatment so that the density change rate before and after entanglement is 2.5 to 3.5 times;
(2) A step of impregnating the fibrous base material with an aqueous dispersion containing a polyurethane precursor having a weight average molecular weight of 50,000 to 100,000 and a crosslinking agent, and then performing a heat drying treatment to form an impregnated sheet containing the fibrous base material and a polyurethane having a hydrophilic group as components;
(3) A step of expressing polyester ultrafine fibers from the ultrafine fiber-expressing fibers of the impregnated sheet to form a pre-heat treatment sheet containing, as components, a fibrous base material composed of polyester ultrafine fibers and polyurethane having a hydrophilic group;
(4) A step of subjecting the pre-heat-treatment sheet to a heat treatment at an atmospheric temperature of 150° C. or more and 200° C. or less for 5 minutes or more and 20 minutes or less.
　以下に、詳細について説明する。 Details are explained below.
　＜繊維質基材を形成する工程＞
　本工程では、極細繊維発現型繊維からなる不織布に、絡合前後での密度変化率が２．５倍以上３．５倍以下となるように絡合処理を施し、繊維質基材を形成する。 <Step of forming fibrous base material>
In this step, a nonwoven fabric made of ultrafine fiber development type fibers is subjected to an entanglement treatment so that the rate of change in density before and after entanglement is 2.5 to 3.5 times, thereby forming a fibrous base material.
　極細繊維発現型繊維としては、溶剤溶解性の異なる２成分（島繊維が芯鞘複合繊維の場合は２または３成分）の熱可塑性樹脂を海成分と島成分とし、前記の海成分を、溶剤などを用いて溶解除去することによって島成分を極細繊維とする海島型複合繊維を用いることが、海成分を除去する際に島成分間、すなわち繊維束内部の極細繊維間に適度な空隙を付与することができるため、人工皮革の風合いや表面品位の観点から好ましい。 As for ultrafine fiber-producing fibers, it is preferable to use sea-island composite fibers in which the sea component and island component are made of two thermoplastic resin components with different solvent solubility (two or three components if the island fiber is a core-sheath composite fiber), and the sea component is dissolved and removed using a solvent or the like to turn the island components into ultrafine fibers, because appropriate gaps can be provided between the island components, i.e., between the ultrafine fibers inside the fiber bundle, when the sea component is removed. This is because this can provide appropriate gaps between the island components, i.e., between the ultrafine fibers inside the fiber bundle, when the sea component is removed. From the perspective of the texture and surface quality of the artificial leather,
　海島型複合繊維としては、海島型複合用口金を用い、海成分と島成分の２成分（島繊維が芯鞘複合繊維の場合は３成分）を相互配列して紡糸する高分子相互配列体を用いる方式が、均一な単繊維直径の極細繊維が得られるという観点から好ましい。 For islands-in-the-sea composite fibers, a method using a polymer mutual alignment body in which two components, the sea component and the island component (three components if the island fiber is a core-sheath composite fiber), are mutually aligned and spun using an islands-in-the-sea composite spinneret is preferred from the viewpoint of obtaining ultrafine fibers with a uniform single fiber diameter.
　海島型複合繊維の海成分としては、ポリエチレン、ポリプロピレン、ポリスチレン、ナトリウムスルホイソフタル酸やポリエチレングリコールなどを共重合した共重合ポリエステル、およびポリ乳酸などを用いることができるが、製糸性や易溶出性等の観点から、ポリスチレンや共重合ポリエステルが好ましく用いられる。 As the sea component of islands-in-the-sea composite fibers, polyethylene, polypropylene, polystyrene, copolymer polyesters copolymerized with sodium sulfoisophthalic acid or polyethylene glycol, and polylactic acid can be used, but polystyrene and copolymer polyesters are preferably used from the viewpoints of spinnability and ease of elution.
　本発明で用いられる海島型複合繊維における海成分と島成分の質量割合は、海成分：島成分＝１０：９０～８０：２０の範囲であることが好ましい。海成分の質量割合が１０質量％以上であると、島成分が十分に極細化されやすくなる。また、海成分の質量割合が８０質量％以下であると、溶出成分の割合が少ないため生産性が向上する。海成分と島成分の質量割合は、より好ましくは、海成分：島成分＝２０：８０～７０：３０の範囲である。 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 in the range of sea component:island component=10:90 to 80:20. When the mass ratio of the sea component is 10% by mass or more, the island component is easily and sufficiently ultra-fine. When the mass ratio of the sea component is 80% by mass or less, the proportion of eluted components is small, improving productivity. The mass ratio of the sea component to the island component is more preferably in the range of sea component:island component=20:80 to 70:30.
　また、繊維質基材を構成する不織布としては、前述の通り短繊維不織布でも長繊維不織布でも用いることができるが、短繊維不織布であると、人工皮革の厚さ方向を向く繊維が長繊維不織布に比べて多くなり、起毛した際の人工皮革の表面に高い緻密感を得ることができるため好ましい。 As mentioned above, either short-fiber or long-fiber nonwoven fabric can be used as the nonwoven fabric that constitutes the fibrous substrate, but short-fiber nonwoven fabric is preferred because it results in more fibers oriented in the thickness direction of the artificial leather than long-fiber nonwoven fabric, and this allows the artificial leather to have a highly dense surface when brushed.
　繊維質基材として短繊維不織布を用いる場合には、得られた極細繊維発現型繊維に、好ましくは捲縮加工を施し、所定長にカット加工して原綿を得る。捲縮加工やカット加工は、公知の方法を用いることができる。 When using a short fiber nonwoven fabric as the fibrous substrate, the resulting ultrafine fiber-developing fibers are preferably subjected to a crimping process and then cut to a predetermined length to obtain raw cotton. The crimping and cutting processes can be carried out using known methods.
　次に、得られた原綿を、クロスラッパー等により不織布とする。そして、得られた不織布に対し、絡合前後での見掛け密度変化率が２．５倍以上３．５倍以下となるように絡合させることにより繊維質基材を得る。この絡合前後での見掛け密度変化率は２．５倍以上、より好ましくは２．７倍以上とすることで、繊維間の絡まりが十分となり、耐久性が向上する。一方、見掛け密度変化率を３．５倍以下、より好ましくは３．２倍以下とすることで、繊維間に親水性基を有するポリウレタンを付与するための十分な空間を維持することができる。不織布を絡合させ繊維質基材を得る方法としては、ニードルパンチ処理やウォータージェットパンチ処理等を用いることができるが、絡合前後での見掛け密度変化率を上記の範囲とするためには、絡合効率の高い、ニードルパンチ処理を行うことが好ましい。 Next, the obtained raw cotton is made into a nonwoven fabric using a cross wrapper or the like. The obtained nonwoven fabric is then entangled so that the apparent density change rate before and after entanglement is 2.5 to 3.5 times to obtain a fibrous base material. By making the apparent density change rate before and after entanglement 2.5 times or more, more preferably 2.7 times or more, the fibers are sufficiently entangled and durability is improved. On the other hand, by making the apparent density change rate 3.5 times or less, more preferably 3.2 times or less, it is possible to maintain sufficient space between the fibers for applying polyurethane having hydrophilic groups. Methods for entangling nonwoven fabric to obtain a fibrous base material include needle punching and water jet punching, but in order to make the apparent density change rate before and after entanglement within the above range, it is preferable to perform needle punching, which has high entanglement efficiency.
　なお、絡合前後での見掛け密度変化率は、繊維質基材の絡合度合いを表す指標であり、以下の式によって求めることができる。
絡合前後での見掛け密度変化率（倍）＝絡合後の繊維質基材の見掛け密度（ｇ／ｃｍ３）／絡合前の不織布の見掛け密度（ｇ／ｃｍ３）
ここで、絡合前、絡合後の繊維ウェブの見掛け密度（ｇ／ｃｍ３）は、ＪＩＳ　Ｌ１９１３：２０１０「一般不織布試験方法」の「６．１　厚さ（ＩＳＯ法）」の「６．１．１　A法」および「６．２　単位面積当たりの質量（ＩＳＯ法）」で規定される方法を用いて繊維ウェブの厚みおよび単位面積当たりの質量を測定し、下記の式を用いて算出される。ここで、繊維ウェブとは、絡合前の不織布および絡合後の繊維質基材の両方を含む。
繊維ウェブの見掛け密度（ｇ／ｃｍ３）＝繊維ウェブの単位面積当たりの質量（ｇ／ｃｍ２）／繊維ウェブの厚み（ｃｍ）。 The rate of change in apparent density before and after entanglement is an index representing the degree of entanglement of the fibrous base material, and can be calculated by the following formula.
Apparent density change rate (times) before and after entanglement=apparent density of fibrous base material after entanglement (g/cm 3 )/apparent density of nonwoven fabric before entanglement (g/cm 3 ).
The apparent density (g/ cm3 ) of the fiber web before and after entanglement is calculated by measuring the thickness and mass per unit area of the fiber web using the method specified in "6.1 Thickness (ISO method)", "6.1.1 A method" and "6.2 Mass per unit area (ISO method)" of JIS L1913:2010 "General nonwoven fabric testing methods", and using the following formula. Here, the fiber web includes both the nonwoven fabric before entanglement and the fibrous base material after entanglement.
Apparent density of a fibrous web (g/cm 3 )=mass per unit area of a fibrous web (g/cm 2 )/thickness of a fibrous web (cm).
　また、不織布を絡合させ繊維質基材を得る方法としては、ニードルパンチ処理やウォータージェットパンチ処理等を用いることができるが、絡合前後での見掛け密度変化率を上記の範囲とするためには、絡合効率の高い、ニードルパンチ処理を行うことが好ましい。 Methods for entangling nonwoven fabrics to obtain a fibrous base material include needle punching and water jet punching, but to keep the apparent density change rate before and after entanglement within the above range, it is preferable to use needle punching, which has high entanglement efficiency.
　ニードルパンチ処理による絡合を行う場合には、原綿の平滑性を向上させ、絡合効率を向上させるために、絡合前の原綿に対し０．０１～３質量％のシリコーンを付与することも好ましい態様である。シリコーンの付与量は、０．０１質量％以上、好ましくは０．０５質量％以上とすることで、絡合効率を高めることができる。一方、３質量％以下、より好ましくは１質量％以下とすることで、加工時に繊維質基材が大きく伸張して人工皮革の品位が低下することを抑制することができる。 When entanglement is performed by needle punching, it is also a preferred embodiment to add 0.01 to 3% by mass of silicone to the raw cotton before entanglement in order to improve the smoothness of the raw cotton and improve entanglement efficiency. By adding silicone in an amount of 0.01% by mass or more, preferably 0.05% by mass or more, it is possible to increase the entanglement efficiency. On the other hand, by adding silicone in an amount of 3% by mass or less, more preferably 1% by mass or less, it is possible to prevent the fibrous base material from stretching too much during processing, which would cause the quality of the artificial leather to deteriorate.
　ニードルパンチ処理による絡合を行う場合に、絡合前後での見掛け密度変化率を上記の値とするためには、用いるニードルとして、５～１５本の繊維を把持可能なバーブ（切り欠き）を備えたニードルを用い、２０００本／ｃｍ２以上４０００本／ｃｍ２以下のパンチ密度でニードルパンチを行うことが好ましい。 When entanglement is performed by needle punching, in order to make the rate of change in apparent density before and after entanglement the above value, it is preferable to use needles equipped with barbs (notches) capable of gripping 5 to 15 fibers, and to perform needle punching at a punch density of 2000 fibers/cm2 or more and 4000 fibers/cm2 or less .
　絡合処理後の複合繊維（極細繊維発現型繊維）からなる繊維質基材の見掛け密度は、０．２０ｇ／ｃｍ３以上０．３０ｇ／ｃｍ３以下であることが好ましい。見掛け密度を０．２０ｇ／ｃｍ３以上、より好ましくは０．２３ｇ／ｃｍ３以上とすることにより、繊維質基材が十分な形態安定性と寸法安定性が得られる。一方、見掛け密度を０．３０ｇ／ｃｍ３以下、より好ましくは０．２８ｇ／ｃｍ３以下とすることにより、親水性基を有するポリウレタンを付与するための十分な空間を維持することができる。 The apparent density of the fibrous substrate made of the composite fiber (ultrafine fiber development type fiber) after the entanglement treatment is preferably 0.20 g/cm 3 or more and 0.30 g/cm 3 or less. By making the apparent density 0.20 g/cm 3 or more, more preferably 0.23 g/cm 3 or more, the fibrous substrate can obtain sufficient shape stability and dimensional stability. On the other hand, by making the apparent density 0.30 g/cm 3 or less, more preferably 0.28 g/cm 3 or less, it is possible to maintain sufficient space for providing polyurethane having a hydrophilic group.
　このようにして得られた繊維質基材は、緻密化の観点から、乾熱もしくは湿熱またはその両者によって収縮させ、さらに高密度化することも好ましい態様である。 From the viewpoint of densification, it is also preferable to shrink the fibrous base material obtained in this manner using dry heat, wet heat, or both to further increase the density.
　＜含浸シートを形成する工程＞
　本工程では、前記繊維質基材に、重量平均分子量が５００００以上１０００００以下のポリウレタン前駆体と、架橋剤とを含有する水分散液を含浸せしめ、次いで、加熱乾燥処理を行って繊維質基材と、親水性基を有するポリウレタンと、を構成要素として含む、含浸シートを形成する。 <Step of forming impregnated sheet>
In this process, the fibrous base material is impregnated with an aqueous dispersion containing a polyurethane precursor having a weight average molecular weight of 50,000 or more and 100,000 or less and a crosslinking agent, and then a heating and drying treatment is performed to form an impregnated sheet containing the fibrous base material and a polyurethane having a hydrophilic group as components.
　水分散液中のポリウレタン前駆体の濃度（水分散液１００質量％中のポリウレタン前駆体の含有量）は、３質量％以上３０質量％以下とすることが好ましい。３質量％以上、より好ましくは５質量％以上とすることで、ポリウレタン前駆体の付与量が少ない場合でも、繊維質基材に均一にポリウレタン前駆体を付与することができる。一方、３０質量％以下、より好ましくは１５質量％以下とすることで、水分散液の貯蔵安定性を高めることができる。 The concentration of the polyurethane precursor in the aqueous dispersion (content of polyurethane precursor in 100% by mass of aqueous dispersion) is preferably 3% by mass or more and 30% by mass or less. By making it 3% by mass or more, more preferably 5% by mass or more, the polyurethane precursor can be applied uniformly to the fibrous substrate even when the amount of polyurethane precursor applied is small. On the other hand, by making it 30% by mass or less, more preferably 15% by mass or less, the storage stability of the aqueous dispersion can be improved.
　本発明に用いられるポリウレタン前駆体の重量平均分子量は、５００００以上１０００００以下であることが重要である。５００００以上、より好ましくは６００００以上であることによって、親水性基を有するポリウレタンの強度、耐久性を高めることができる。一方、１０００００以下、より好ましくは９００００以下、さらに好ましくは８００００以下とすることによって、風合いの柔軟な人工皮革とすることができる。 It is important that the weight average molecular weight of the polyurethane precursor used in the present invention is 50,000 or more and 100,000 or less. By making it 50,000 or more, and more preferably 60,000 or more, the strength and durability of the polyurethane having hydrophilic groups can be increased. On the other hand, by making it 100,000 or less, more preferably 90,000 or less, and even more preferably 80,000 or less, it is possible to produce artificial leather with a soft feel.
　本発明においてポリウレタン前駆体の重量平均分子量は、前述の溶解成分の重量平均分子量と同様の方法にて測定することができる。 In the present invention, the weight average molecular weight of the polyurethane precursor can be measured in the same manner as the weight average molecular weight of the dissolved component described above.
　繊維質基材に水分散液を含浸せしめた後、乾熱凝固法や液中凝固法などの当分野で通常用いられる凝固方法を用いて凝固を行うことができる。乾熱凝固法を用いる場合、水分散液を繊維質基材に付与後、１２０℃以上１８０℃以下の温度で加熱処理し、乾熱凝固させることで、繊維質基材に親水性基を有するポリウレタンを付与することが好ましい。また、液中凝固法を用いる場合、ｐＨ１以上３以下の凝固溶媒にて凝固処理を行う酸凝固法、または、８０℃以上１００℃以下の熱水にて凝固処理を行う熱水凝固法等を用いることができる。 After the fibrous base material is impregnated with the aqueous dispersion, coagulation can be performed using a coagulation method commonly used in this field, such as a dry heat coagulation method or a liquid coagulation method. When using a dry heat coagulation method, it is preferable to apply the aqueous dispersion to the fibrous base material, heat treat it at a temperature of 120°C to 180°C, and perform dry heat coagulation to apply a polyurethane having hydrophilic groups to the fibrous base material. When using a liquid coagulation method, it is possible to use an acid coagulation method in which coagulation is performed using a coagulation solvent with a pH of 1 to 3, or a hot water coagulation method in which coagulation is performed using hot water with a pH of 80°C to 100°C.
　本発明の人工皮革の製造方法において、乾熱凝固法を用いる場合、水分散液中に無機塩を含有することができる。無機塩を含有することで、水分散液に感熱凝固性を付与することができる。本発明において、感熱凝固性とは、水分散液を加熱した際に、ある温度（感熱凝固温度）に達すると水分散液の流動性が減少し、凝固する性質のことをいう。 When the dry heat coagulation method is used in the manufacturing method of the artificial leather of the present invention, an inorganic salt can be contained in the aqueous dispersion. By containing an inorganic salt, the aqueous dispersion can be given heat-sensitive coagulation properties. In the present invention, heat-sensitive coagulation properties refer to the property that when the aqueous dispersion is heated, the fluidity of the aqueous dispersion decreases and the aqueous dispersion coagulates when a certain temperature (heat-sensitive coagulation temperature) is reached.
　水分散液の感熱凝固温度は、５５℃以上８０℃以下であることが好ましい。感熱凝固温度を５５℃以上、より好ましくは６０℃以上とすることで、水分散液の調合時や貯蔵時のゲル化を抑制することができる。一方、８０℃以下、より好ましくは７０℃以下とすることで、繊維質基材から水分が蒸発する前にポリウレタン前駆体の凝固が進行することで、溶剤系のポリウレタンを湿式凝固させて得られる場合に類似した構造、すなわちポリウレタンが強く繊維を拘束しない構造を形成することができ、良好な柔軟性、反発感を達成することが可能となる。 The heat-sensitive coagulation temperature of the aqueous dispersion is preferably 55°C or higher and 80°C or lower. By setting the heat-sensitive coagulation temperature at 55°C or higher, more preferably 60°C or higher, gelation during preparation and storage of the aqueous dispersion can be suppressed. On the other hand, by setting the temperature at 80°C or lower, more preferably 70°C or lower, coagulation of the polyurethane precursor proceeds before water evaporates from the fibrous base material, and a structure similar to that obtained by wet coagulation of solvent-based polyurethane can be formed, i.e., a structure in which the polyurethane does not strongly bind the fibers, making it possible to achieve good flexibility and resilience.
　本発明では、感熱凝固剤として無機塩を用いる場合、１価陽イオン含有無機塩を用いることが好ましい。前記の１価陽イオン含有無機塩は、好ましくは塩化ナトリウムおよび／または硫酸ナトリウムである。イオン価数が小さい１価陽イオン含有無機塩は、水分散液の安定性への影響が小さく、添加量を調整することで水分散液の安定性を担保しながらにして、感熱凝固温度を厳密に制御することができる。 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 above-mentioned inorganic salt containing a monovalent cation is preferably sodium chloride and/or sodium sulfate. An inorganic salt containing a monovalent cation, which has a small ionic valence, has little effect on the stability of the aqueous dispersion, and by adjusting the amount added, the heat-sensitive coagulation temperature can be strictly controlled while ensuring the stability of the aqueous dispersion.
　さらに本発明では、水分散液中の１価陽イオン含有無機塩の含有量が、ポリウレタン前駆体に対して１０質量％以上５０質量％以下であることが好ましい。含有量を１０質量％以上、より好ましくは２０質量％以上、さらに好ましくは３０質量％以上とすることで、水分散液中に多量に存在するイオンが、ポリウレタン前駆体粒子に均一に作用することで、特定の感熱凝固温度において速やかに凝固を完了させることができる。これにより、前述のような、繊維質基材中に多量の水分を含有した状態でポリウレタン前駆体の凝固を進行させることにおいて、より顕著な効果を得ることができる。その結果、溶剤系のポリウレタンを湿式凝固させて得られる場合に非常に類似した構造を形成し、良好な柔軟性、反発感を達成することが可能である。さらに、添加量を上記とすることで、無機塩がポリウレタン前駆体の粒子の融着における阻害剤となり、連続被膜形成によるポリウレタン前駆体の硬化を抑制することもできる。一方で、含有量を５０質量％以下とすることで、適度なポリウレタン前駆体の連続被膜構造を残存させ、物性の低下を抑えることができる。また水分散液の安定性も保持することができる。 Furthermore, in the present invention, the content of the monovalent cation-containing inorganic salt in the aqueous dispersion is preferably 10% by mass or more and 50% by mass or less with respect to the polyurethane precursor. By making the content 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 aqueous dispersion act uniformly on the polyurethane precursor particles, and coagulation can be completed quickly at a specific heat-sensitive coagulation temperature. This makes it possible to obtain a more remarkable effect in proceeding with the coagulation of the polyurethane precursor in a state in which a large amount of moisture is contained in the fibrous base material as described above. As a result, it is possible to form a structure very similar to that obtained by wet coagulation of a solvent-based polyurethane, and to achieve good flexibility and resilience. Furthermore, by making the amount added as described above, the inorganic salt acts as an inhibitor in the fusion of the polyurethane precursor particles, and it is also possible to suppress the hardening of the polyurethane precursor due to the formation of a continuous film. On the other hand, by making the content 50% by mass or less, it is possible to leave an appropriate continuous film structure of the polyurethane precursor and suppress the deterioration of physical properties. It is also possible to maintain the stability of the aqueous dispersion.
　本発明の人工皮革の製造方法では、水分散液に架橋剤を含有させることが重要である。架橋剤によってポリウレタン前駆体に３次元網目構造を導入することで、耐摩耗性等の物性を向上させることができる。 In the method for producing artificial leather of the present invention, it is important that the aqueous dispersion contains a crosslinking agent. By using the crosslinking agent to introduce a three-dimensional network structure into the polyurethane precursor, physical properties such as abrasion resistance can be improved.
　前記の水分散液における架橋剤の濃度は、ポリウレタン前駆体の質量に対して１質量％以上１０質量％以下とすることが好ましい。水分散液における架橋剤の濃度を１質量％以上、より好ましくは２質量％以上とすることで、架橋剤によってポリウレタン前駆体に３次元網目構造をより多く導入でき、耐摩耗性等に優れた人工皮革を得ることができる。一方で、架橋剤の濃度を１０質量％以下、より好ましくは７質量％以下とすることで、ポリウレタン前駆体が形成される際に、過剰な架橋剤がポリウレタン前駆体の凝固を阻害してしまうことを抑制し、耐摩耗性等の物性の低下を抑制しやすくなる。 The concentration of the crosslinking agent in the aqueous dispersion is preferably 1% by mass or more and 10% by mass or less relative to the mass of the polyurethane precursor. By making the concentration of the crosslinking agent in the aqueous dispersion 1% by mass or more, more preferably 2% by mass or more, the crosslinking agent can introduce a greater amount of three-dimensional network structure into the polyurethane precursor, resulting in an artificial leather with excellent abrasion resistance, etc. On the other hand, by making the concentration of the crosslinking agent 10% by mass or less, more preferably 7% by mass or less, it is possible to prevent excess crosslinking agent 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.
　本発明の人工皮革の製造方法に係る架橋剤は、カルボジイミド系架橋剤および／またはブロックイソシアネート架橋剤であることが好ましい。このようにすることで、人工皮革中の高分子弾性体の分子内に、耐光性や耐熱性、耐摩耗性等の物性、および柔軟性に優れるＮ－アシルウレア結合および／またはイソウレア結合によって３次元架橋構造を付与させることができ、人工皮革の柔軟性を保持しながら、耐久性や耐摩耗性等の物性を飛躍的に向上させることができる。 The crosslinking agent in the method for producing artificial leather of the present invention is preferably a carbodiimide-based crosslinking agent and/or a blocked isocyanate crosslinking agent. In this way, a three-dimensional crosslinking structure can be imparted to the molecules of the polymeric elastomer in the artificial leather by 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 the artificial leather can be dramatically improved in physical properties such as durability and abrasion resistance while maintaining its flexibility.
　そして、前記の水分散液を含浸せしめた後、加熱乾燥処理を行って繊維質基材と、親水性基を有するポリウレタンと、を構成要素として含む、含浸シートを形成する。 After impregnating the substrate with the aqueous dispersion, a heat drying process is carried out to form an impregnated sheet containing the fibrous base material and polyurethane having hydrophilic groups as its components.
　水分散液を含浸せしめた後の、加熱乾燥処理の温度としては、１１０℃以上であることが好ましく、より好ましくは１２０℃以上である。加熱乾燥処理の温度を１１０℃以上とすることによって、シートの乾燥効率を高めるだけでなく、架橋反応の進行を促進することができ、人工皮革の耐久性や耐摩耗性等の物性をより高いものとすることができる。一方、加熱乾燥処理の温度を１８０℃以下、１７０℃以下とすることで、親水性基を有するポリウレタンの熱劣化を抑制することができる。 After impregnation with the aqueous dispersion, the temperature for the heat drying process is preferably 110°C or higher, and more preferably 120°C or higher. By setting the heat drying process temperature at 110°C or higher, not only can the drying efficiency of the sheet be increased, but the progress of the crosslinking reaction can be promoted, and the physical properties of the artificial leather, such as durability and abrasion resistance, can be improved. On the other hand, by setting the heat drying process temperature at 180°C or lower, or 170°C or lower, thermal deterioration of polyurethane having hydrophilic groups can be suppressed.
　加熱乾燥処理の時間は５分以上、３０分以下であることが好ましい。５分以上、より好ましくは１０分以上加熱することで、架橋反応の進行を促進することが可能となる。加熱時間を３０分以下、好ましくは２５分以下とすることで、過剰加熱による親水性基を有するポリウレタンの熱劣化を抑制することができる。 The time for the heat drying process is preferably 5 minutes or more and 30 minutes or less. Heating for 5 minutes or more, more preferably 10 minutes or more, can promote the progress of the crosslinking reaction. Heating for 30 minutes or less, preferably 25 minutes or less, can suppress thermal degradation of polyurethane having hydrophilic groups due to excessive heating.
　＜熱処理前シートを形成する工程＞
　本工程では、前記の含浸シートの極細繊維発現型繊維からポリエステル極細繊維を発現させ、ポリエステル極細繊維で構成されてなる繊維質基材と、親水性基を有するポリウレタンと、を構成要素として含む熱処理前シートを形成する。 <Step of forming pre-heat treatment sheet>
In this process, polyester ultrafine fibers are developed from the ultrafine fiber-developing fibers of the impregnated sheet, and a pre-heat treatment sheet is formed containing, as components, a fibrous base material composed of polyester ultrafine fibers and polyurethane having hydrophilic groups.
　極細繊維発現型繊維として海島型複合繊維を用いる場合の繊維極細化処理（脱海処理）は、例えば、溶剤中に海島型複合繊維を浸漬した後に、加熱処理を行うなどの方法で行うことができる。海成分を溶解する溶剤としては、海成分の種類により適宜選択することができる。海成分が共重合ポリエステルの場合には、水酸化ナトリウム水溶液などのアルカリ水溶液を用いることができる。 When using islands-in-sea composite fibers as ultrafine fiber-producing fibers, the ultrafine fiber processing (sea-removal processing) can be carried out, for example, by immersing the islands-in-sea composite fibers in a solvent and then carrying out a heat treatment. The solvent for dissolving the sea component can be appropriately selected depending on the type of sea component. When the sea component is a copolymer polyester, an alkaline aqueous solution such as an aqueous sodium hydroxide solution can be used.
　脱海処理の溶剤としてアルカリ水溶液を用いる場合、親水性基を有するポリウレタンの過剰な劣化を防止するため、アルカリ水溶液のモル濃度としては３ｍｏｌ／Ｌ以下であることが好ましい。 When using an alkaline aqueous solution as a solvent for the sea-removal process, it is preferable that the molar concentration of the alkaline aqueous solution be 3 mol/L or less to prevent excessive deterioration of the polyurethane containing hydrophilic groups.
　＜熱処理を行う工程＞
　本工程では、前記の熱処理前シートを、１５０℃以上２００℃以下の雰囲気温度で、５分以上２０分以下、熱処理を行う。 <Heat treatment process>
In this step, the pre-heat-treatment sheet is subjected to a heat treatment at an atmospheric temperature of 150° C. or more and 200° C. or less for 5 minutes or more and 20 minutes or less.
　この熱処理は、前記の熱処理前シートが得られた後に行うが、工程での伸びによる品位低下を抑制するため、極細繊維化処理を行った直後に行うことが好ましい。 This heat treatment is carried out after the pre-heat treatment sheet is obtained, but it is preferable to carry it out immediately after the ultrafine fiber processing to prevent deterioration of quality due to elongation during the process.
　熱処理の方法としては、フロータードライヤーやドラムドライヤー、ピンテンターなどの熱風乾燥機を用いることが好ましい。 The preferred method of heat treatment is to use a hot air dryer such as a floater dryer, drum dryer, or pin tenter.
　この熱処理においては、１５０℃以上２００℃以下の雰囲気温度で、５分以上２０分以下の加熱時間とすることが重要である。このようにすることで、極細繊維と親水性基を有するポリウレタンの接着性を向上させて人工皮革の強度や耐摩耗性を向上させつつ、親水性基を有するポリウレタンの一部を低分子量化させることで人工皮革を柔軟化させ、柔軟な風合いと優れた耐摩耗性を両立した人工皮革とすることができる。 In this heat treatment, it is important to heat the material at an ambient temperature of 150°C to 200°C for a heating time of 5 to 20 minutes. This improves the adhesion between the ultrafine fibers and the polyurethane with hydrophilic groups, improving the strength and abrasion resistance of the artificial leather, while lowering the molecular weight of part of the polyurethane with hydrophilic groups to soften the artificial leather, resulting in an artificial leather that combines a soft feel with excellent abrasion resistance.
　まず、雰囲気温度は１５０℃以上２００℃以下とすることが重要である。温度を１５０℃以上、より好ましくは１５５℃以上とすることで、極細繊維と親水性基を有するポリウレタンとの間の接着性が向上し、人工皮革の強度や耐摩耗性を向上させることができるだけでなく、親水性基を有するポリウレタンの一部を低分子量化させ、人工皮革の柔軟性を高めることができる。一方で、温度を２００℃以下、好ましくは１９０℃以下、より好ましくは１８０℃以下とすることで、親水性基を有するポリウレタンの一部を緩やかに低分子量化させることができる。 First, it is important that the atmospheric temperature be 150°C or higher and 200°C or lower. By setting the temperature at 150°C or higher, and more preferably at 155°C or higher, the adhesion between the ultrafine fibers and the polyurethane having hydrophilic groups is improved, and not only can the strength and abrasion resistance of the artificial leather be improved, but also a portion of the polyurethane having hydrophilic groups can be reduced in molecular weight, increasing the flexibility of the artificial leather. On the other hand, by setting the temperature at 200°C or lower, preferably 190°C or lower, and more preferably 180°C or lower, a portion of the polyurethane having hydrophilic groups can be gradually reduced in molecular weight.
　次に、加熱時間は、５分以上２０分以下とすることが重要である。加熱時間を５分以上、好ましくは６分以上とすることで、極細繊維と親水性基を有するポリウレタンとの間の接着性が向上し、人工皮革の強度や耐摩耗性を向上させることができる。一方で、加熱時間を２０分以下、好ましくは１５分以下、より好ましくは１２分以下とすることで、親水性基を有するポリウレタンの低分子量化が過剰となってしまうことによる、人工皮革の物性の低下を防ぐことができる。 Next, it is important that the heating time is between 5 and 20 minutes. By setting the heating time to 5 minutes or more, and preferably 6 minutes or more, the adhesion between the ultrafine fibers and the polyurethane having hydrophilic groups is improved, and the strength and abrasion resistance of the artificial leather can be improved. 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 caused by excessive reduction in the molecular weight of the polyurethane having hydrophilic groups.
　＜仕上げ工程＞
　本発明の人工皮革の製造方法においても、一般的な人工皮革と同様に、種々の仕上げ工程を行うことが好ましい。 <Finishing process>
In the method for producing the artificial leather of the present invention, it is preferable to carry out various finishing steps, as in the case of general artificial leathers.
　まず、本発明の人工皮革の製造方法は、人工皮革を染色する染色工程を含むことが好ましい。この染色処理としては、当分野で通常用いられる各種方法を採用することができる。例えば、ジッガー染色機や液流染色機を用いた液流染色処理、連続染色機を用いたサーモゾル染色処理等の浸染処理、あるいはローラー捺染、スクリーン捺染、インクジェット方式捺染、昇華捺染および真空昇華捺染等による立毛面への捺染処理等を用いることができる。中でも、未起毛人工皮革または人工皮革の染色と同時に揉み効果を与えて未起毛人工皮革または人工皮革を柔軟化することができることから、液流染色機を用いることが好ましい。また、必要に応じて、染色後に各種の樹脂仕上げ加工を施すことができる。 First, the method for producing the artificial leather of the present invention preferably includes a dyeing step for dyeing the artificial leather. As the dyeing process, various methods commonly used in this field can be adopted. For example, a liquid flow dyeing process using a jigger dyeing machine or a liquid flow dyeing machine, a dip dyeing process such as a thermosol dyeing process using a continuous dyeing machine, or a printing process on the napped surface by roller printing, screen printing, inkjet printing, sublimation printing, vacuum sublimation printing, etc. can be used. Among them, it is preferable to use a liquid flow dyeing machine, since it is possible to soften the unbrushed artificial leather or artificial leather by imparting a kneading effect to the unbrushed artificial leather or artificial leather while dyeing it. In addition, various resin finishing processes can be applied after dyeing, if necessary.
　また、染色と同浴または染色後に、例えば、シリコーン等の柔軟剤、帯電防止剤、撥水剤、難燃剤、耐光剤および抗菌剤等を用いた仕上げ剤処理を施すことができる。 Furthermore, finishing treatments can be applied using softeners such as silicone, antistatic agents, water repellents, flame retardants, light fasteners, antibacterial agents, etc. in the same bath as dyeing or after dyeing.
　本発明では、染色工程の前後に問わず、製造効率の観点から、厚み方向に半裁することも好ましい態様である。 In the present invention, from the viewpoint of manufacturing efficiency, it is also a preferred embodiment to cut the film in half in the thickness direction, regardless of whether it is before or after the dyeing process.
　本発明の人工皮革の製造方法においては、染色工程の前後に問わず、立毛を形成する起毛工程を含むことも好ましい。立毛を形成する方法は、特に限定されず、サンドペーパー等によるバフィング等、当分野で通常行われる各種方法を用いることができる。 In the manufacturing method of the artificial leather of the present invention, it is also preferable to include a nap raising step for forming naps, whether before or after the dyeing step. The method for forming naps is not particularly limited, and various methods commonly used in this field, such as buffing with sandpaper, can be used.
　起毛処理を施す場合には、起毛処理の前にシリコーンエマルジョンなどの滑剤を人工皮革の表面へ付与することができる。また、起毛処理の前に帯電防止剤を付与することで、研削によって人工皮革から発生した研削粉がサンドペーパー上に堆積しにくくなる。このようにして、人工皮革が形成される。 When applying a nap-raising treatment, a lubricant such as a silicone emulsion can be applied to the surface of the artificial leather before the nap-raising treatment. Also, by applying an antistatic agent before the nap-raising treatment, grinding dust generated from the artificial leather during grinding is less likely to accumulate on the sandpaper. In this way, the artificial leather is formed.
　さらに、本発明の人工皮革の製造方法では、必要に応じて、人工皮革に対し、例えば、パーフォレーション等の穴開け加工、エンボス加工、レーザー加工、ピンソニック加工、および、プリント加工等の後加工処理を施すことができる。 Furthermore, in the method for producing 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 necessary.
　実施例を用いて本発明の人工皮革についてさらに具体的に説明するが、本発明はこれらの実施例のみに限定されるものではない。 The artificial leather of the present invention will be explained in more detail using examples, but the present invention is not limited to these examples.
　［評価方法］
　実施例で用いた評価法とその測定条件について説明する。なお、各物性の測定において、特段の記載がないものは、前記の方法に基づいて測定を行ったものである。 [Evaluation method]
The evaluation methods and measurement conditions used in the examples are described below. Unless otherwise specified, the measurements of each physical property were performed according to the above-mentioned methods.
　（１）平均単繊維直径（μｍ）：
　平均単繊維直径（μｍ）は、走査型電子顕微鏡（ＳＥＭ）として、株式会社キーエンス製「ＶＨＸ－Ｄ５００／Ｄ５１０」を用い、上記の方法によって測定、算出した。 (1) 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.
　（２）ポリウレタン前駆体、溶解成分の重量平均分子量（単位なし）：
　ポリウレタン前駆体、または、溶解成分の重量平均分子量は、下記の装置を用い、かつ、下記の条件として、上記の方法によって測定、算出した。
・機器：ＨＬＣ－８０２０（東ソー株式会社製）
・カラム：ＴＳＫｇｅｌ　ＧＭＨ－ＸＬ（東ソー株式会社製）
・溶媒：Ｎ，Ｎ－ジメチルホルムアミド（ＤＭＦ）
・温度：４０℃
・校正用標準試料：ポリスチレン（東ソー株式会社製「ＴＳＫ　ｓｔａｎｄａｒｄ　ＰＯＬＹＳＴＹＲＥＮＥ」）
・流量：１．０ｍｌ／分。 (2) Weight average molecular weight of polyurethane precursor, dissolved component (unitless):
The weight average molecular weight of the polyurethane precursor or the dissolved component was measured and calculated by the above-mentioned method using the following apparatus and under the following conditions.
・Equipment: HLC-8020 (manufactured by Tosoh Corporation)
Column: TSKgel GMH-XL (manufactured by Tosoh Corporation)
Solvent: N,N-dimethylformamide (DMF)
Temperature: 40°C
Calibration standard sample: polystyrene ("TSK standard POLYSTYRENE" manufactured by Tosoh Corporation)
Flow rate: 1.0 ml/min.
　（３）親水性基を有するポリウレタンが、N－アシルウレア結合および／またはイソウレア結合を有することの確認
　赤外分光分析の測定装置として日本分光株式会社製「ＦＴ／ＩＲ　４６００」を用い、以下の方法によって確認した。人工皮革から５ｃｍ×５ｃｍの試験片を切り出し、その試験片をヘキサフルオロイソプロパノールに浸漬させ、人工皮革からポリエステル極細繊維を溶出した。次に、不溶成分（親水性基を有するポリウレタン）を１００℃の乾燥機で乾燥した後に赤外分光分析を行い、１６５０ｃｍ－１付近に観測されるN－アシルウレア結合および／またはイソウレア結合由来のＣ＝Ｏ伸縮振動のピークが観測された場合に、親水性基を有するポリウレタンが、N－アシルウレア結合および／またはイソウレア結合を有すると判断した。 (3) Confirmation that polyurethane having hydrophilic group has N-acylurea bond and/or isourea bond Confirmation was performed by the following method using JASCO Corporation's "FT/IR 4600" as an infrared spectroscopy measurement device. A 5 cm x 5 cm test piece was cut out from the artificial leather, and the test piece was immersed in hexafluoroisopropanol to elute polyester ultrafine fibers from the artificial leather. Next, the insoluble component (polyurethane having hydrophilic group) was dried in a dryer at 100°C and then subjected to infrared spectroscopy analysis. When a peak of C=O stretching vibration derived from N-acylurea bond and/or isourea bond was observed near 1650 cm -1 , it was determined that polyurethane having hydrophilic group has N-acylurea bond and/or isourea bond.
　（４）親水性基を有するポリウレタンの含有割合（質量％）：
　親水性基を有するポリウレタンの含有割合（質量％）は、上記の方法によって測定、算出した。 (4) Content of polyurethane having hydrophilic group (mass%):
The content (mass %) of the polyurethane having a hydrophilic group was measured and calculated by the above-mentioned method.
　（５）親水性基を有するポリウレタンの質量保持率（％）：
　親水性基を有するポリウレタンの質量保持率（％）は、上記の方法によって測定、算出した。 (5) Mass retention (%) of polyurethane having hydrophilic group:
The mass retention (%) of the polyurethane having a hydrophilic group was measured and calculated by the above-mentioned method.
　（６）人工皮革の見掛け密度（ｇ／ｃｍ３）：
　人工皮革の見掛け密度（ｇ／ｃｍ３）は、厚み計として株式会社尾崎製作所製「ダイヤルシックネスゲージ　型式H」を用い、上記の方法によって測定、算出した。 (6) Apparent density of artificial leather (g/cm 3 ):
The apparent density (g/cm 3 ) of the artificial leather was measured and calculated by the above-mentioned method using a "Dial Thickness Gauge Model H" manufactured by Ozaki Seisakusho Co., Ltd. as a thickness gauge.
　（７）立毛長（μｍ）：
　立毛長は、走査型電子顕微鏡（ＳＥＭ）として、株式会社キーエンス製「ＶＨＸ－Ｄ５００／Ｄ５１０」を用い、上記の方法によって測定、算出した。 (7) Pile length (μm):
The nap length was measured and calculated by the above-mentioned method using a scanning electron microscope (SEM) "VHX-D500/D510" manufactured by Keyence Corporation.
　（８）人工皮革の摩耗減量（ｍｇ）：
　人工皮革の摩耗減量（ｍｇ）の測定、算出に際しては、マーチンデール摩耗試験機として、Ｊａｍｅｓ　Ｈ．Ｈｅａｌ＆Ｃｏ．製「Ｍｏｄｅｌ　４０６」を、標準摩擦布として同社の「ＡＢＲＡＳＴＩＶＥ　ＣＬＯＴＨ　ＳＭ２５」を用いた。そして、人工皮革に１２ｋＰａの荷重をかけ、摩耗回数は５００００回とした。摩耗前後の人工皮革の質量を用いて、下記の式により、摩耗減量を算出した。
摩耗減量（ｍｇ）＝摩耗前の質量（ｍｇ）－摩耗後の質量（ｍｇ）
なお、摩耗減量（ｍｇ）は小数点以下第１位の値を四捨五入した値を摩耗減量とした。 (8) Abrasion loss of artificial leather (mg):
When measuring and calculating the abrasion loss (mg) of the artificial leather, a Martindale abrasion tester "Model 406" manufactured by James H. Heal & Co. was used as the abrasion tester, and "ABRASTIVE CLOTH SM25" manufactured by the same company was used as the standard friction cloth. A load of 12 kPa was applied to the artificial leather, and the number of abrasions was set to 50,000. The abrasion loss was calculated by the following formula using the mass of the artificial leather before and after abrasion.
Abrasion loss (mg) = mass before abrasion (mg) - mass after abrasion (mg)
The abrasion loss (mg) was calculated by rounding off the value to the first decimal place.
　（９）人工皮革の風合い
　健康な成人２０名を評価者として、人工皮革の風合いを、下記のようにＡ、Ｂ、Ｃで評価し、最も多かった評価を人工皮革の触感とした。本発明において良好なレベルは、「ＡまたはＢ」である。
Ａ：握った際に抵抗感がなく、柔らかい
Ｂ：握った際にやや抵抗感があるが、柔らかい
Ｃ：握った際の抵抗感が大きく、硬い。 (9) Texture of artificial leather Twenty healthy adults were asked to evaluate the texture of the artificial leather with a rating of A, B, or C, as shown below, and the most common rating was taken as the feel of the artificial leather. In the present invention, a good level is "A or B."
A: No resistance when gripped, soft B: Some resistance when gripped, but soft C: High resistance when gripped, hard.
　［ポリウレタン前駆体］
　実施例、比較例で用いたポリウレタン前駆体は、以下のとおりである。
ＰＵ－Ａ：　高分子ポリオールとしてポリテトラメチレングリコール、有機ジイソシアネートとしてＭＤＩ、親水性基を有する活性水素成分含有化合物として２，２－ジメチロールプロピオン酸、鎖伸長剤としてエチレングリコールを用いた、重量平均分子量が８００００のポリウレタン前駆体。
ＰＵ－Ｂ：　高分子ポリオールとしてポリテトラメチレングリコール、有機ジイソシアネートとしてＭＤＩ、親水性基を有する活性水素成分含有化合物として２，２－ジメチロールプロピオン酸、鎖伸長剤としてエチレングリコールを用いた、重量平均分子量が５５０００のポリウレタン前駆体。
ＰＵ－Ｃ：　高分子ポリオールとしてポリテトラメチレングリコール、有機ジイソシアネートとしてＭＤＩ、親水性基を有する活性水素成分含有化合物として２，２－ジメチロールプロピオン酸、鎖伸長剤としてエチレングリコールを用いた、重量平均分子量が９００００のポリウレタン前駆体。
ＰＵ－Ｄ：　高分子ポリオールとしてポリテトラメチレングリコールとポリヘキサメチレンカーボネートをモル比３：１で共重合したポリオール、有機ジイソシアネートとしてＭＤＩ、親水性基を有する活性水素成分含有化合物として２，２－ジメチロールプロピオン酸、鎖伸長剤としてエチレングリコールを用いた、重量平均分子量が８００００のポリウレタン前駆体。
ＰＵ－Ｅ：　高分子ポリオールとしてポリテトラメチレングリコール、有機ジイソシアネートとしてＭＤＩ、親水性基を有する活性水素成分含有化合物として２，２－ジメチロールプロピオン酸、鎖伸長剤としてエチレングリコールを用いた、重量平均分子量が１１００００のポリウレタン前駆体。 [Polyurethane precursor]
The polyurethane precursors used in the examples and comparative examples are as follows.
PU-A: A polyurethane precursor having a weight average molecular weight of 80,000, which uses polytetramethylene glycol as a polymer polyol, MDI as an organic diisocyanate, 2,2-dimethylolpropionic acid as an active hydrogen component-containing compound having a hydrophilic group, and ethylene glycol as a chain extender.
PU-B: A polyurethane precursor having a weight average molecular weight of 55,000, which uses polytetramethylene glycol as a polymer polyol, MDI as an organic diisocyanate, 2,2-dimethylolpropionic acid as an active hydrogen component-containing compound having a hydrophilic group, and ethylene glycol as a chain extender.
PU-C: A polyurethane precursor having a weight average molecular weight of 90,000, which uses polytetramethylene glycol as a polymer polyol, MDI as an organic diisocyanate, 2,2-dimethylolpropionic acid as an active hydrogen component-containing compound having a hydrophilic group, and ethylene glycol as a chain extender.
PU-D: A polyurethane precursor having a weight average molecular weight of 80,000, which uses a polyol obtained by copolymerizing polytetramethylene glycol and polyhexamethylene carbonate in a molar ratio of 3:1 as the high molecular weight polyol, MDI as the organic diisocyanate, 2,2-dimethylolpropionic acid as the active hydrogen component-containing compound having a hydrophilic group, and ethylene glycol as the chain extender.
PU-E: A polyurethane precursor having a weight average molecular weight of 110,000, which uses polytetramethylene glycol as a polymer polyol, MDI as an organic diisocyanate, 2,2-dimethylolpropionic acid as an active hydrogen component-containing compound having a hydrophilic group, and ethylene glycol as a chain extender.
　［実施例１］
　＜繊維質基材を形成する工程＞
　海成分として５－スルホイソフタル酸ナトリウムを８モル％共重合したポリエステルを用い、島成分として固有粘度が０．７３のポリエチレンテレフタレートを用いて、島数が１６島／ホールの海島型複合用口金を用いて、紡糸温度が２８５℃、島／海質量比率が８０／２０、吐出量が１．６ｇ／分・ホール、紡糸速度が１１００ｍ／分の条件で溶融紡糸した。次いで、得られた繊維を油剤液浴中で３．７倍に延伸するとともに、繊維質量に対して０．５質量％のジメチルシリコーンを付与（以降、「原綿に対するシリコーンの付与量」が０．５質量％であると記載）した後に、５１ｍｍの長さにカットし、単繊維繊度が３．８ｄｔｅｘの海島型複合繊維の原綿を得た。次に、上記の海島型複合繊維の原綿を用いて、カードおよびクロスラッパー工程を経て見掛け密度が０．０９ｇ／ｃｍ３の積層ウェブを形成した。最大１０本の原綿を把持可能（以降、「ニードルバーブの最大把持本数」が１０本であると記載）なバーブを備えたニードルを用いて３５００本／ｃｍ２のパンチ密度で、前記積層ウェブをニードルパンチ処理して、目付が７００ｇ／ｍ２で、厚みが２．６ｍｍ、見掛け密度が０．２７ｇ／ｃｍ３（絡合前後での密度変化率３．0倍）の繊維質基材を得た。得られた繊維質基材を９８℃の温度の湯中に２分間浸漬させて収縮させた後に、１００℃の温度で５分間乾燥させ、海島型複合繊維の不織布からなる繊維質基材を得た。 [Example 1]
<Step of forming fibrous base material>
A polyester copolymerized with 8 mol% of sodium 5-sulfoisophthalate was used as the sea component, and a polyethylene terephthalate having an intrinsic viscosity of 0.73 was used as the island component. The melt spinning was performed using an islands-in-sea composite spinneret with 16 islands/hole under the conditions of a spinning temperature of 285°C, an islands/sea mass ratio of 80/20, a discharge rate of 1.6 g/min/hole, and a spinning speed of 1100 m/min. The obtained fiber was then stretched 3.7 times in an oil solution bath, and 0.5% by mass of dimethyl silicone was added to the fiber mass (hereinafter, the "amount of silicone added to the raw cotton" is described as 0.5% by mass), and then cut to a length of 51 mm to obtain raw cotton of islands-in-sea composite fiber with a single fiber fineness of 3.8 dtex. The raw cotton of the islands-in-sea composite fiber was then used to form a laminated web with an apparent density of 0.09 g/ cm3 through carding and cross-wrapping processes. The laminated web was needle-punched at a punch density of 3,500/ cm2 using needles equipped with barbs capable of gripping a maximum of 10 raw cotton fibers (hereinafter, the "maximum number of needle barbs that can be gripped" is referred to as 10) to obtain a fibrous base material having a basis weight of 700 g/ m2 , a thickness of 2.6 mm, and an apparent density of 0.27 g/ cm3 (a density change rate of 3.0 times before and after entanglement). The obtained fibrous base material was immersed in hot water at a temperature of 98°C for 2 minutes to cause it to shrink, and then dried at a temperature of 100°C for 5 minutes to obtain a fibrous base material consisting of a nonwoven fabric of islands-in-the-sea type composite fibers.
　＜含浸シートを形成する工程＞
　ポリウレタン前駆体として、「ＰＵ－Ａ」が１１質量部、架橋剤Ａ（カルボジイミド系架橋剤、日清紡ケミカル株式会社製「カルボジライトＶ－０２－Ｌ２」）が１質量部、硫酸ナトリウムが５質量部、水が８３質量部からなる水分散液を調製した。該水分散液に前記繊維質基材を含浸した後に、水分散液のピックアップ率が２００％となるようにマングルで絞り、さらに１２０℃の熱風で２０分間加熱することによって、ポリウレタン前駆体を凝固させるとともにN－アシルウレア結合および／またはイソウレア結合からなる架橋構造を形成し、海島型複合繊維の不織布と親水性基を有するポリウレタンとからなる含浸シートを得た。 <Step of forming impregnated sheet>
An aqueous dispersion containing 11 parts by mass of "PU-A" as a polyurethane precursor, 1 part by mass of crosslinking agent A (a carbodiimide crosslinking agent, "Carbodilite V-02-L2" manufactured by Nisshinbo Chemical Inc.), 5 parts by mass of sodium sulfate, and 83 parts by mass of water was prepared. The fibrous base material was impregnated with the aqueous dispersion, and then squeezed with a mangle so that the pick-up rate of the aqueous dispersion was 200%, and further heated with hot air at 120°C for 20 minutes to coagulate the polyurethane precursor and form a crosslinked structure consisting of N-acylurea bonds and/or isourea bonds, thereby obtaining an impregnated sheet consisting of a nonwoven fabric of islands-in-the-sea type composite fibers and a polyurethane having a hydrophilic group.
　＜熱処理前シートを形成する工程＞
　得られた含浸シートを、５％の水酸化ナトリウム水溶液に浸漬した後に、水酸化ナトリウム水溶液のピックアップ率が１００％となるようにマングルで絞り、さらに９５℃のスチームで１０分間熱処理することで海島型複合繊維の海成分をアルカリ分解し、次いで余剰の水酸化ナトリウムおよび硫酸ナトリウムを水洗して、熱処理前シートを得た。 <Step of forming pre-heat treatment sheet>
The obtained impregnated sheet was immersed in a 5% aqueous sodium hydroxide solution, and then squeezed with a mangle so that the pick-up rate of the aqueous sodium hydroxide solution became 100%, and further heat-treated with steam at 95° C. for 10 minutes to alkali-decompose the sea component of the islands-in-sea type composite fibers, and then the excess sodium hydroxide and sodium sulfate were washed away with water to obtain a pre-heat-treatment sheet.
　＜熱処理を行う工程＞
　水洗後の熱処理前シートを、雰囲気温度を１６０℃に昇温させたピンテンターで１０分間熱処理し、極細繊維からなる繊維質基材と親水性基を有するポリウレタンとからなるシートを得た。 <Heat treatment process>
The water-washed pre-heat-treatment sheet was heat-treated for 10 minutes in a pin tenter with an atmospheric temperature raised to 160° C. to obtain a sheet composed of a fibrous base material made of ultrafine fibers and polyurethane having hydrophilic groups.
　＜仕上げ工程＞
　得られたシートを厚さ方向に垂直に半裁し、半裁面の反対側をサンドペーパー番手１２０番のエンドレスサンドペーパーで研削することにより、厚みが０．７０ｍｍの立毛シートを得た。 <Finishing process>
The obtained sheet was cut in half perpendicular to the thickness direction, and the opposite side to the half-cut surface was ground with endless sandpaper of sandpaper size 120 to obtain a napped sheet having a thickness of 0.70 mm.
　得られた立毛シートを、液流染色機を用いて１２０℃の温度条件下で分散染料を用いて黒色に染色を行った。染色された立毛シートを乾燥機で乾燥し、極細繊維の平均単繊維直径が４．４μｍで、２３質量％の親水性基を有するポリウレタンを含む人工皮革を得た。得られた人工皮革は柔軟な風合いと優れた耐久性を有していた。結果を表１に示す。 The resulting napped sheet was dyed black using a disperse dye at a temperature of 120°C using a liquid jet dyeing machine. The dyed napped sheet was dried in a dryer to obtain an artificial leather containing polyurethane with an average single fiber diameter of 4.4 μm and 23% by mass of hydrophilic groups. The resulting artificial leather had a soft feel and excellent durability. The results are shown in Table 1.
　［実施例２］
　＜含浸シートを形成する工程＞において、ポリウレタン前駆体を「ＰＵ－Ｂ」に変えた以外は実施例１と同様にして、極細繊維の平均単繊維直径が４．４μｍで、２３質量％の親水性基を有するポリウレタンを含む人工皮革を得た。得られた人工皮革は柔軟な風合いと優れた耐久性を有していた。結果を表１に示す。 [Example 2]
An artificial leather containing polyurethane having an average single fiber diameter of ultrafine fibers of 4.4 μm and 23 mass % of hydrophilic groups was obtained in the same manner as in Example 1, except that in the step of forming an impregnated sheet, the polyurethane precursor was changed to "PU-B". The obtained artificial leather had a soft feel and excellent durability. The results are shown in Table 1.
　［実施例３］
　＜含浸シートを形成する工程＞において、ポリウレタン前駆体を「ＰＵ－Ｃ」に変えた以外は実施例１と同様にして、極細繊維の平均単繊維直径が４．４μｍで、２３質量％の親水性基を有するポリウレタンを含む人工皮革を得た。得られた人工皮革はやや抵抗感があるものの柔軟な風合いと優れた耐久性を有していた。結果を表１に示す。 [Example 3]
An artificial leather containing polyurethane having an average single fiber diameter of 4.4 μm and 23 mass % of hydrophilic groups was obtained in the same manner as in Example 1, except that in the step of forming an impregnated sheet, the polyurethane precursor was changed to "PU-C". The artificial leather obtained had a slightly resistant feel, but had a soft texture and excellent durability. The results are shown in Table 1.
　［実施例４］
　＜含浸シートを形成する工程＞において、水分散液のピックアップ率を１５０％に変えた以外は実施例１と同様にして、極細繊維の平均単繊維直径が４．４μｍで、１８質量％の親水性基を有するポリウレタンを含む人工皮革を得た。得られた人工皮革は柔軟な風合いと優れた耐久性を有していた。結果を表１に示す。 [Example 4]
An artificial leather was obtained in the same manner as in Example 1, except that in the step of forming an impregnated sheet, the pick-up rate of the aqueous dispersion was changed to 150%, and the ultrafine fibers had an average single fiber diameter of 4.4 μm and contained 18% by mass of polyurethane having a hydrophilic group. The obtained artificial leather had a soft feel and excellent durability. The results are shown in Table 1.
　［実施例５］
　＜含浸シートを形成する工程＞において、ポリウレタン前駆体を「ＰＵ－Ｄ」に変えた以外は実施例１と同様にして、極細繊維の平均単繊維直径が４．４μｍで、２３質量％の親水性基を有するポリウレタンを含む人工皮革を得た。得られた人工皮革はやや抵抗感があるものの柔軟な風合いと優れた耐久性を有していた。結果を表１に示す。 [Example 5]
An artificial leather containing polyurethane having an average single fiber diameter of 4.4 μm and 23 mass % of hydrophilic groups was obtained in the same manner as in Example 1, except that in the step of forming an impregnated sheet, the polyurethane precursor was changed to "PU-D". The artificial leather obtained had a slightly resistant feel but a soft texture and excellent durability. The results are shown in Table 1.
　［実施例６］
　＜熱処理を行う工程＞において、熱処理の雰囲気温度を１８０℃に変えた以外は実施例１と同様にして、極細繊維の平均単繊維直径が４．４μｍで、２３質量％の親水性基を有するポリウレタンを含む人工皮革を得た。得られた人工皮革は柔軟な風合いと優れた耐久性を有していた。結果を表１に示す。 [Example 6]
An artificial leather was obtained in the same manner as in Example 1, except that in the <step of performing heat treatment>, the atmospheric temperature of the heat treatment was changed to 180° C., and the ultrafine fibers had an average single fiber diameter of 4.4 μm and contained 23% by mass of polyurethane having a hydrophilic group. The obtained artificial leather had a soft feel and excellent durability. The results are shown in Table 1.
　［実施例７］
　＜熱処理を行う工程＞において、熱処理時間を１５分に変えた以外は実施例１と同様にして、極細繊維の平均単繊維直径が４．４μｍで、２３質量％の親水性基を有するポリウレタンを含む人工皮革を得た。得られた人工皮革は柔軟な風合いと優れた耐久性を有していた。結果を表２に示す。 [Example 7]
An artificial leather was obtained in the same manner as in Example 1, except that the heat treatment time was changed to 15 minutes in the <step of performing heat treatment>, in which the average single fiber diameter of the ultrafine fibers was 4.4 μm and the polyurethane contained 23 mass % of a hydrophilic group. The obtained artificial leather had a soft feel and excellent durability. The results are shown in Table 2.
　［実施例８］
　＜熱処理を行う工程＞において、熱処理の雰囲気温度を１５０℃に変えた以外は実施例１と同様にして、極細繊維の平均単繊維直径が４．４μｍで、２３質量％の親水性基を有するポリウレタンを含む人工皮革を得た。得られた人工皮革はやや抵抗感があるものの柔軟な風合いと優れた耐久性を有していた。結果を表２に示す。 [Example 8]
An artificial leather was obtained in the same manner as in Example 1, except that in the <step of performing heat treatment>, the atmospheric temperature of the heat treatment was changed to 150° C., and the ultrafine fibers had an average single fiber diameter of 4.4 μm and contained 23% by mass of polyurethane having hydrophilic groups. The obtained artificial leather had a slightly resistant feel, but had a soft texture and excellent durability. The results are shown in Table 2.
　［実施例９］
　＜繊維質基材を形成する工程＞において、原綿にジメチルシリコーンを付与しなかったこと以外は実施例１と同様にして、極細繊維の平均単繊維直径が４．４μｍで、２３質量％の親水性基を有するポリウレタンを含む人工皮革を得た。得られた人工皮革は柔軟な風合いと優れた耐久性を有していた。結果を表２に示す。 [Example 9]
An artificial leather was obtained in the same manner as in Example 1, except that in the <step of forming a fibrous base material>, dimethyl silicone was not added to the raw cotton, and the average single fiber diameter of the ultrafine fibers was 4.4 μm, and the artificial leather contained 23 mass % of polyurethane having a hydrophilic group. The obtained artificial leather had a soft feel and excellent durability. The results are shown in Table 2.
　［実施例１０］
　＜繊維質基材を形成する工程＞において、原綿にジメチルシリコーンを付与せず、３０００本／ｃｍ２のパンチ本数でニードルパンチ処理した以外は実施例１と同様にして、極細繊維の平均単繊維直径が４．４μｍで、２３質量％の親水性基を有するポリウレタンを含む人工皮革を得た。得られた人工皮革は柔軟な風合いと優れた耐久性を有していた。結果を表２に示す。 [Example 10]
In the <step of forming a fibrous base material>, dimethyl silicone was not added to the raw cotton, and needle punching was performed with a punch count of 3000/ cm2 , in the same manner as in Example 1, to obtain an artificial leather having an average single fiber diameter of ultrafine fibers of 4.4 μm and containing 23% by mass of polyurethane having a hydrophilic group. The obtained artificial leather had a soft feel and excellent durability. The results are shown in Table 2.
　［比較例１］
　＜熱処理を行う工程＞において、熱処理時間を３０分に変えた以外は実施例１と同様にして、極細繊維の平均単繊維直径が４．４μｍで、２３質量％の親水性基を有するポリウレタンを含む人工皮革を得た。得られた人工皮革は柔軟な風合いを有しているものの、耐久性に大きく劣るものであった。結果を表３に示す。 [Comparative Example 1]
An artificial leather was obtained in the same manner as in Example 1, except that in the <step of performing heat treatment>, the heat treatment time was changed to 30 minutes, and the ultrafine fibers had an average single fiber diameter of 4.4 μm and contained 23 mass % of polyurethane having hydrophilic groups. The obtained artificial leather had a soft feel, but was significantly inferior in durability. The results are shown in Table 3.
　［比較例２］
　＜含浸シートを形成する工程＞において、ポリウレタン前駆体を「ＰＵ－Ｅ」に変えた以外は実施例１と同様にして、極細繊維の平均単繊維直径が４．４μｍで、２３質量％の親水性基を有するポリウレタンを含む人工皮革を得た。得られた人工皮革は優れた耐久性を有するものの、風合いが硬いものであった。結果を表３に示す。 [Comparative Example 2]
An artificial leather containing polyurethane having an average single fiber diameter of ultrafine fibers of 4.4 μm and 23 mass % of hydrophilic groups was obtained in the same manner as in Example 1, except that in the step of forming an impregnated sheet, the polyurethane precursor was changed to "PU-E". The obtained artificial leather had excellent durability, but had a hard feel. The results are shown in Table 3.
　［比較例３］
　＜含浸シートを形成する工程＞において、水分散液のピックアップ率を１１０％に変えた以外は実施例１と同様にして、極細繊維の平均単繊維直径が４．４μｍで、１３質量％の親水性基を有するポリウレタンを含む人工皮革を得た。得られた人工皮革は柔軟な風合いを有しているものの、耐久性に大きく劣るものであった。結果を表３に示す。 [Comparative Example 3]
An artificial leather was obtained in the same manner as in Example 1, except that in the step of forming an impregnated sheet, the pick-up rate of the aqueous dispersion was changed to 110%, and the ultrafine fibers had an average single fiber diameter of 4.4 μm and contained 13% by mass of polyurethane having hydrophilic groups. The artificial leather obtained had a soft feel, but was significantly inferior in durability. The results are shown in Table 3.
　［比較例４］
　＜含浸シートを形成する工程＞において、水分散液のピックアップ率を２５０％に変えた以外は実施例１と同様にして、極細繊維の平均単繊維直径が４．４μｍで、２９質量％の親水性基を有するポリウレタンを含む人工皮革を得た。得られた人工皮革は優れた耐久性を有するものの、風合いが硬いものであった。結果を表３に示す。 [Comparative Example 4]
An artificial leather was obtained in the same manner as in Example 1, except that in the step of forming an impregnated sheet, the pick-up rate of the aqueous dispersion was changed to 250%, and the average single fiber diameter of the ultrafine fibers was 4.4 μm, and the artificial leather contained 29% by mass of polyurethane having hydrophilic groups. The artificial leather obtained had excellent durability, but had a hard feel. The results are shown in Table 3.
　［比較例５］
　＜繊維質基材を形成する工程＞において、原綿にジメチルシリコーンを付与せず、２５００本／ｃｍ２のパンチ本数でニードルパンチ処理した以外は比較例１と同様にして、極細繊維の平均単繊維直径が４．４μｍで、２３質量％の親水性基を有するポリウレタンを含む人工皮革を得た。得られた人工皮革は柔軟な風合いを有しているものの、耐久性に大きく劣るものであった。結果を表４に示す。 [Comparative Example 5]
In the <step of forming a fibrous base material>, dimethyl silicone was not added to the raw cotton, and needle punching was performed with a punch count of 2500/ cm2 , in the same manner as in Comparative Example 1, to obtain an artificial leather having an average single fiber diameter of ultrafine fibers of 4.4 μm and containing 23% by mass of polyurethane having a hydrophilic group. The obtained artificial leather had a soft feel, but was significantly inferior in durability. The results are shown in Table 4.
　［比較例６］
　＜繊維質基材を形成する工程＞において、ニードルパンチに用いるニードルとして「ニードルバーブの最大把持本数」が６本のニードルを用いた以外は比較例５と同様にして、極細繊維の平均単繊維直径が４．４μｍで、２３質量％の親水性基を有するポリウレタンを含む人工皮革を得た。得られた人工皮革は柔軟な風合いを有しているものの、耐久性に大きく劣るものであった。結果を表４に示す。 [Comparative Example 6]
In the <Step of forming a fibrous base material>, an artificial leather was obtained in the same manner as in Comparative Example 5, except that a needle with a "maximum number of needle barbs that can be held" of six was used as the needle used for needle punching. The average single fiber diameter of the ultrafine fibers was 4.4 μm, and the artificial leather contained 23% by mass of polyurethane having hydrophilic groups. The obtained artificial leather had a soft texture, but was significantly inferior in durability. The results are shown in Table 4.
　［比較例７］
　＜熱処理を行う工程＞において、熱処理時間を３分に変えた以外は実施例２と同様にして、極細繊維の平均単繊維直径が４．４μｍで、２３質量％の親水性基を有するポリウレタンを含む人工皮革を得た。得られた人工皮革は柔軟な風合いを有しているものの、耐久性に大きく劣るものであった。結果を表４に示す。 [Comparative Example 7]
An artificial leather was obtained in the same manner as in Example 2, except that the heat treatment time was changed to 3 minutes in the <step of performing heat treatment>, in which the average single fiber diameter of the ultrafine fibers was 4.4 μm and the polyurethane contained 23 mass % of a hydrophilic group. The obtained artificial leather had a soft feel, but was significantly inferior in durability. The results are shown in Table 4.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000002
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000003
Figure JPOXMLDOC01-appb-T000004
Figure JPOXMLDOC01-appb-T000004
１：立毛部
２：基体部 1: hair-raising portion 2: base portion

Claims (8)

  1. 　平均単繊維直径が０．１μｍ以上１０．０μｍ以下のポリエステル極細繊維で構成されてなる繊維質基材と、親水性基を有するポリウレタンと、を構成要素として含む人工皮革であって、前記人工皮革における前記親水性基を有するポリウレタンの含有割合が１５質量％以上２５質量％以下であって、前記人工皮革を２５℃のＮ，Ｎ－ジメチルホルムアミドに２４時間浸漬させた後の前記親水性基を有するポリウレタンの質量保持率が５０質量%以上８０質量%以下であり、前記人工皮革を２５℃のＮ，Ｎ－ジメチルホルムアミドに２４時間浸漬させた後に該Ｎ，Ｎ－ジメチルホルムアミド中に溶解している成分の重量平均分子量が５００００以上１０００００以下である、人工皮革。 An artificial leather containing as its components a fibrous base material made of polyester ultrafine fibers with an average single fiber diameter of 0.1 μm to 10.0 μm, and a polyurethane having a hydrophilic group, the content of the polyurethane having a hydrophilic group in the artificial leather being 15% by mass to 25% by mass, the mass retention rate of the polyurethane having a hydrophilic group after the artificial leather is immersed in N,N-dimethylformamide at 25°C for 24 hours is 50% by mass to 80% by mass, and the weight average molecular weight of the component dissolved in N,N-dimethylformamide after the artificial leather is immersed in N,N-dimethylformamide at 25°C for 24 hours is 50,000 to 100,000.
  2. 　人工皮革の見掛け密度が０．３０ｇ／ｃｍ３以上０．４０ｇ／ｃｍ３以下である、請求項１に記載の人工皮革。 2. The artificial leather according to claim 1, wherein the apparent density of the artificial leather is 0.30 g/cm3 or more and 0.40 g/ cm3 or less.
  3. 　前記親水性基を有するポリウレタンがポリエステルポリオールに由来する構成成分を含む、請求項１または２に記載の人工皮革。 The artificial leather according to claim 1 or 2, wherein the polyurethane having hydrophilic groups contains a component derived from a polyester polyol.
  4. 　前記親水性基を有するポリウレタンがさらにポリカーボネートポリオールに由来する構成成分を含む、請求項３に記載の人工皮革。 The artificial leather according to claim 3, wherein the polyurethane having hydrophilic groups further contains a component derived from a polycarbonate polyol.
  5. 　前記親水性基を有するポリウレタンが、N－アシルウレア結合および／またはイソウレア結合を有する、請求項１または２に記載の人工皮革。 The artificial leather according to claim 1 or 2, wherein the polyurethane having a hydrophilic group has an N-acylurea bond and/or an isourea bond.
  6. 　下記（１）～（４）の工程をこの順に含む、請求項１に記載の人工皮革の製造方法：
    （１）極細繊維発現型繊維からなる不織布に、絡合前後での密度変化率が２．５倍以上３．５倍以下となるように絡合処理を施し、繊維質基材を形成する工程；
    （２）前記繊維質基材に、重量平均分子量が５００００以上１０００００以下のポリウレタン前駆体と、架橋剤とを含有する水分散液を含浸せしめ、次いで、加熱乾燥処理を行って繊維質基材と、親水性基を有するポリウレタンと、を構成要素として含む、含浸シートを形成する工程；
    （３）前記含浸シートの極細繊維発現型繊維からポリエステル極細繊維を発現させ、ポリエステル極細繊維で構成されてなる繊維質基材と、前記親水性基を有するポリウレタンと、を構成要素として含む熱処理前シートを形成する工程；
    （４）前記熱処理前シートを、１５０℃以上２００℃以下の雰囲気温度で、５分以上２０分以下、熱処理を行う工程。     A method for producing the artificial leather according to claim 1, comprising the following steps (1) to (4) in this order:
    (1) A step of forming a fibrous base material by subjecting a nonwoven fabric made of ultrafine fiber-developing fibers to an entanglement treatment so that the density change rate before and after entanglement is 2.5 to 3.5 times;
    (2) A step of impregnating the fibrous base material with an aqueous dispersion containing a polyurethane precursor having a weight average molecular weight of 50,000 to 100,000 and a crosslinking agent, and then performing a heat drying treatment to form an impregnated sheet containing the fibrous base material and a polyurethane having a hydrophilic group as components;
    (3) A step of expressing polyester ultrafine fibers from the ultrafine fiber-expressing fibers of the impregnated sheet to form a pre-heat treatment sheet containing, as components, a fibrous base material composed of polyester ultrafine fibers and the polyurethane having a hydrophilic group;
    (4) A step of subjecting the pre-heat-treatment sheet to a heat treatment at an atmospheric temperature of 150° C. or more and 200° C. or less for 5 minutes or more and 20 minutes or less.
  7. 　前記架橋剤がカルボジイミド系架橋剤である、請求項６に記載の人工皮革の製造方法。 The method for producing artificial leather according to claim 6, wherein the crosslinking agent is a carbodiimide crosslinking agent.
  8. 　前記（１）の工程において、前記極細繊維発現型繊維の質量に対し０．０１質量％以上３質量％以下のシリコーンを付与する、請求項６または７に記載の人工皮革の製造方法。 The method for producing artificial leather according to claim 6 or 7, wherein in step (1), 0.01% by mass or more and 3% by mass or less of silicone is added to the ultrafine fiber-developing fiber.
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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1192656A (en) * 1997-09-24 1999-04-06 Kuraray Co Ltd Urethane resin composition excellent in yellowing resistance and leather like sheet using the same
JP2000303371A (en) * 1999-04-20 2000-10-31 Kuraray Co Ltd Production of leather-like sheet
JP2000355885A (en) * 1999-06-16 2000-12-26 Kuraray Co Ltd Production of leather-mode sheetlike material
JP2005054345A (en) * 2003-07-18 2005-03-03 Toray Ind Inc Ultrafine staple fiber nonwoven fabric and leather-like article in sheet form, and method for their production
JP2014019983A (en) * 2012-07-20 2014-02-03 Toray Ind Inc Sheet-like object and production method of the same
WO2016063761A1 (en) * 2014-10-24 2016-04-28 東レ株式会社 Sheet-like article
JP2017172074A (en) * 2016-03-24 2017-09-28 東レ株式会社 Sheet-like article and manufacturing method therefor
JP2021021172A (en) * 2019-07-30 2021-02-18 東レ株式会社 Sheet-like material and method for producing the same
JP2022101943A (en) * 2020-12-25 2022-07-07 東レ株式会社 Artificial leather

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1192656A (en) * 1997-09-24 1999-04-06 Kuraray Co Ltd Urethane resin composition excellent in yellowing resistance and leather like sheet using the same
JP2000303371A (en) * 1999-04-20 2000-10-31 Kuraray Co Ltd Production of leather-like sheet
JP2000355885A (en) * 1999-06-16 2000-12-26 Kuraray Co Ltd Production of leather-mode sheetlike material
JP2005054345A (en) * 2003-07-18 2005-03-03 Toray Ind Inc Ultrafine staple fiber nonwoven fabric and leather-like article in sheet form, and method for their production
JP2014019983A (en) * 2012-07-20 2014-02-03 Toray Ind Inc Sheet-like object and production method of the same
WO2016063761A1 (en) * 2014-10-24 2016-04-28 東レ株式会社 Sheet-like article
JP2017172074A (en) * 2016-03-24 2017-09-28 東レ株式会社 Sheet-like article and manufacturing method therefor
JP2021021172A (en) * 2019-07-30 2021-02-18 東レ株式会社 Sheet-like material and method for producing the same
JP2022101943A (en) * 2020-12-25 2022-07-07 東レ株式会社 Artificial leather

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