WO2024095846A1 - Cuir artificiel et son procédé de fabrication - Google Patents

Cuir artificiel et son procédé de fabrication 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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English (en)
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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  • Chemical & Material Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Dispersion Chemistry (AREA)
  • Engineering & Computer Science (AREA)
  • Textile Engineering (AREA)
  • Synthetic Leather, Interior Materials Or Flexible Sheet Materials (AREA)

Abstract

L'invention concerne un cuir artificiel qui comprend, en tant qu'éléments constitutifs, un matériau de base fibreux configuré à partir de fines fibres de polyester ayant un diamètre moyen de fibre individuelle de 0,1 à 10,0 µm, et un polyuréthane qui a un groupe hydrophile, le rapport de teneur du polyuréthane ayant un groupe hydrophile dans le cuir artificiel étant de 15 à 25 % en masse, le rapport de maintien de masse du polyuréthane ayant un groupe hydrophile après que le cuir artificiel a été immergé pendant 24 heures dans du N, N-diméthyl formamide à 25 °C étant de 50 à 80 % en masse, et la masse moléculaire moyenne en poids d'un composant dissous dans du N, N-diméthyl formamide à 25 °C après que le cuir artificiel a été immergé pendant 24 heures dans le N, N-diméthyl formamide à 25 °C étant de 50 000 à 100 000. L'invention concerne un cuir artificiel et son procédé de fabrication, avec lesquels à la fois une texture souple et une durabilité exceptionnelle sont obtenues tout en utilisant un procédé respectueux de l'environnement dans lequel aucun solvant organique n'est utilisé.
PCT/JP2023/038438 2022-10-31 2023-10-25 Cuir artificiel et son procédé de fabrication WO2024095846A1 (fr)

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Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1192656A (ja) * 1997-09-24 1999-04-06 Kuraray Co Ltd 耐黄変性に優れたポリウレタン樹脂組成物及びこれを用いた皮革様シート
JP2000303371A (ja) * 1999-04-20 2000-10-31 Kuraray Co Ltd 皮革様シート状物の製造方法
JP2000355885A (ja) * 1999-06-16 2000-12-26 Kuraray Co Ltd 皮革様シート状物の製造方法
JP2005054345A (ja) * 2003-07-18 2005-03-03 Toray Ind Inc 極細短繊維不織布および皮革様シート状物ならびにそれらの製造方法
JP2014019983A (ja) * 2012-07-20 2014-02-03 Toray Ind Inc シート状物およびその製造方法
WO2016063761A1 (fr) * 2014-10-24 2016-04-28 東レ株式会社 Article du type feuille
JP2017172074A (ja) * 2016-03-24 2017-09-28 東レ株式会社 シート状物およびその製造方法
JP2021021172A (ja) * 2019-07-30 2021-02-18 東レ株式会社 シート状物およびその製造方法
JP2022101943A (ja) * 2020-12-25 2022-07-07 東レ株式会社 人工皮革

Patent Citations (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH1192656A (ja) * 1997-09-24 1999-04-06 Kuraray Co Ltd 耐黄変性に優れたポリウレタン樹脂組成物及びこれを用いた皮革様シート
JP2000303371A (ja) * 1999-04-20 2000-10-31 Kuraray Co Ltd 皮革様シート状物の製造方法
JP2000355885A (ja) * 1999-06-16 2000-12-26 Kuraray Co Ltd 皮革様シート状物の製造方法
JP2005054345A (ja) * 2003-07-18 2005-03-03 Toray Ind Inc 極細短繊維不織布および皮革様シート状物ならびにそれらの製造方法
JP2014019983A (ja) * 2012-07-20 2014-02-03 Toray Ind Inc シート状物およびその製造方法
WO2016063761A1 (fr) * 2014-10-24 2016-04-28 東レ株式会社 Article du type feuille
JP2017172074A (ja) * 2016-03-24 2017-09-28 東レ株式会社 シート状物およびその製造方法
JP2021021172A (ja) * 2019-07-30 2021-02-18 東レ株式会社 シート状物およびその製造方法
JP2022101943A (ja) * 2020-12-25 2022-07-07 東レ株式会社 人工皮革

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