Surface treatment agent for leather and leather surface-treated with same

Abstract

The present invention provides a surface treatment agent for leather, which contains (A) a resin capable of forming a resin layer on the surface of a base material for leather, and (B) a compound having two or more active hydrogen atoms in one molecule.

Description

Technical Field

[0001] The invention relates to a surface treatment agent for leather and leather surface-treated with the surface treatment agent. Background Art

[0002] Leather represented by synthetic leather, polyvinyl chloride (PVC) leather, etc., with an epidermis (PU epidermis) composed of polyurethane resin, is bonded to soft polyurethane foam to form a cushioning composite material, which is used in a wide range of fields such as automotive interior materials and furniture due to its good touch. This type of cushioning composite material is manufactured by the so-called flame lamination method of using flames, etc. to burn and melt the surface of soft polyurethane foam, and then pasting synthetic leather, etc. thereon. However, in the cushioning composite material manufactured by the flame lamination method, there is a problem of yellowing of the leather surface. In the past, due to the use of dark-colored synthetic leathers such as black and gray, the discoloration of the leather surface was not obvious and did not cause major problems, but in recent years, due to the large-scale use of light-colored synthetic leathers such as white and beige, the discoloration of the leather surface is obvious and becomes a major problem. For this reason, it is necessary to be able to suppress the method for yellowing of the leather surface of the cushioning composite material manufactured by the flame lamination method.

[0003] In addition, as a method for suppressing the yellowing of the soft polyurethane foam itself, for example, there is known a method of adding a phosphorus antioxidant and a hindered amine light stabilizer to a foaming raw material containing a polyol, an aromatic polyisocyanate, a blowing agent and a catalyst (Japanese Patent Publication No. 2010-100717 (Patent Document 1)); and a method of producing a non-yellowing soft polyurethane foam using a polyurethane foam raw material containing at least a polyol component, an aliphatic or alicyclic polyisocyanate component, a foam stabilizer, a catalyst and a blowing agent, wherein the polyol component contains a specific polyoxyalkylene polyol (Japanese Patent Publication No. 2010-150438 (Patent Document 2)).

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent Application Publication No. 2010-100717

[0007] Patent Document 2: Japanese Patent Application Publication No. 2010-150438 Summary of the invention

[0008] Problems to be solved by the invention

[0009] The present invention has been made in view of the above-mentioned problems existing in the prior art, and an object of the present invention is to provide a surface treatment agent capable of suppressing yellowing of the leather surface and leather with suppressed yellowing of the surface.

[0010] Technical means to solve problems

[0011] The present inventors have conducted intensive studies to achieve the above-mentioned purpose and have found that the yellowing of the leather surface in a cushioning composite material formed by laminating a soft polyurethane foam with various leathers by flame lamination is caused by NO contained in the gas generated from the soft polyurethane foam during the combustion process using flames or the like. x The present invention also found that the generation of NO can be suppressed by treating the surface of a leather substrate with a surface treating agent containing a compound having two or more active hydrogen atoms in one molecule. x The present invention is completed by using the gas to yellow the leather surface.

[0012] That is, the present invention provides the following embodiments.

[0013] [1] A leather surface treatment agent comprising: (A) a resin capable of forming a resin layer on a surface of a leather substrate; and (B) a compound having two or more active hydrogen atoms in one molecule.

[0014] [2] The leather surface treatment agent according to [1], wherein the (B) compound having two or more active hydrogen atoms in one molecule is a compound having three or more hydroxyl groups in one molecule.

[0015] [3] The leather surface treatment agent according to [1] or [2], wherein the (B) compound having two or more active hydrogen atoms in one molecule is a glycerol compound.

[0016] [4] The leather surface treatment agent according to any one of [1] to [3], wherein the resin (A) capable of forming a resin layer on the surface of the leather substrate is at least one selected from a polyurethane resin and an acrylic resin.

[0017] [5] A leather comprising a leather substrate and a surface-treated layer formed on a surface of the leather substrate using the leather surface-treating agent according to any one of [1] to [4].

[0018] [6] A cushioning composite material comprising a soft polyurethane foam and the leather according to [5] bonded to a surface of the soft polyurethane foam.

[0019] Effects of the Invention

[0020] According to the present invention, a surface treatment agent capable of suppressing yellowing of a leather surface and leather with suppressed yellowing of the surface can be provided. DETAILED DESCRIPTION

[0021] Hereinafter, the present invention will be described in detail according to preferred embodiments.

[0022] [Surface treatment agent for leather]

[0023] First, the leather surface treatment agent of the present invention is described. The leather surface treatment agent of the present invention (hereinafter also referred to as "surface treatment agent") contains (A) a resin capable of forming a resin layer on the surface of a leather substrate and (B) a compound having two or more active hydrogen atoms in one molecule. Each component is described below.

[0024] (A) Resin

[0025] The resin (A) used in the present invention is not particularly limited as long as it can form a resin layer on the surface of the leather substrate. For example, polyurethane resin, acrylic resin, polyester resin, polyolefin resin, polyvinyl chloride resin, silicone resin, polyurethane acrylate resin, vinyl acetate resin, ethylene-vinyl acetate resin, styrene-butadiene resin, acrylonitrile-butadiene resin, polyamide resin, epoxy resin, etc. can be enumerated as the resin of the base resin when forming the resin layer (resin film). These resins can be appropriately selected according to the material on the leather substrate surface, and one can be used alone, or two or more can be used in combination. In addition, in the above-mentioned resin, when the material on the leather substrate surface is polyurethane resin, polyvinyl chloride resin, polyolefin resin, from the viewpoint of the adhesion of the surface treated layer formed by the surface treating agent and the leather substrate surface, polyurethane resin and acrylic resin are preferably used.

[0026] (Polyurethane resin)

[0027] The polyurethane resin is not particularly limited, and for example, a polyurethane resin obtained by reacting at least an organic polyisocyanate, a polyol, and a polyamine having two or more amino groups and / or imino groups can be cited. The method for producing such polyurethane resin is not particularly limited, and a conventionally known method can be used. In addition, in the present invention, any water-based polyurethane resin and solvent-based polyurethane resin can also be used.

[0028] In addition, among the above polyurethane resins, from the viewpoint of the wear resistance and bending resistance of leather, the neutralized product of the isocyanate-terminated prepolymer which is a reaction product of (a) an organic polyisocyanate, (b) a polyol, and (c) a compound having an anionic hydrophilic group and at least two active hydrogen atoms, and the chain extension product of (d) a polyamine having two or more amino groups and / or imino groups, i.e., a self-emulsifying waterborne polyurethane resin is preferred. It should be noted that the "waterborne" in the above self-emulsifying waterborne polyurethane resin means that after the self-emulsifying polyurethane resin is emulsified and dispersed in water to prepare an emulsified dispersion having a resin component concentration of 35% by mass, even if the emulsified dispersion is left standing at 20° C. for 12 hours, no separation or precipitation is observed.

[0029] (a) Organic polyisocyanates

[0030] The above-mentioned (a) organic polyisocyanate is not particularly limited, and examples thereof include aromatic, aliphatic and alicyclic polyisocyanates that have been commonly used. For example, examples of aromatic polyisocyanates include m-phenylene diisocyanate, p-phenylene diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, 4,4'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate, 3,3'-dimethyl-4,4'-biphenyl diisocyanate, 3,3'-dichloro-4,4'-biphenyl diisocyanate, 1,5-naphthalene diisocyanate, dimethylbiphenyl diisocyanate, tetramethylenexylene diisocyanate, and xylene diisocyanate. As aliphatic polyisocyanates, tetramethylene diisocyanate, pentamethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, trimethyl hexamethylene diisocyanate, lysine diisocyanate, etc. can be cited. As alicyclic polyisocyanates, isophorone diisocyanate, hydrogenated xylene diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 3,3'-dimethyl-4,4'-dicyclohexylmethane diisocyanate, norbornane diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, etc. can be cited. These organic polyisocyanates can be used alone or in combination of two or more. In addition, among these organic polyisocyanates, from the viewpoint that the obtained self-emulsifying waterborne polyurethane resin is a resin without yellowing, preferably aliphatic polyisocyanates and alicyclic polyisocyanates are used, and from the viewpoint of heat resistance, more preferably alicyclic polyisocyanates are used.

[0031] (b) Polyols

[0032] There are no particular restrictions on the above-mentioned (b) polyols, and examples thereof include previously known high molecular weight polyols such as polyether polyols, polyester polyols, polycarbonate polyols, previously known low molecular weight diols, polyols having at least three or more active hydrogen atoms, and the like. One of these polyols may be used alone, or two or more of them may be used in combination. It should be noted that, in this specification, the above-mentioned high molecular weight polyols and the above-mentioned low molecular weight diols are also collectively referred to as "(b1) polyols", and the above-mentioned polyols having at least three or more active hydrogen atoms are referred to as "(b2) polyols". The above-mentioned (b1) polyols may be used alone, or in combination with the above-mentioned (b2) polyols. In addition, the above-mentioned (b2) polyols are preferably used in combination with the above-mentioned (b1) polyols.

[0033] There are no particular restrictions on the above-mentioned polyether polyols, and examples thereof include polymers of alkylene oxides such as ethylene oxide, propylene oxide, and butylene oxide. Such polymers may be homopolymers of one alkylene oxide or copolymers of two or more alkylene oxides. In the case of copolymers, they may be random copolymers or block copolymers. In addition, there are no particular restrictions on the molecular weight of such polyether polyols, but it is preferably 400 to 5000. In addition, as the above-mentioned polyether polyols, compounds obtained by adding one or more alkylene oxides to low molecular weight diols may be used. As the above-mentioned low molecular weight diols, ethylene glycol, propylene glycol, 1,4-butanediol, etc. may be mentioned.

[0034] The polyester polyol is not particularly limited, and examples thereof include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 1,6-hexanediol, neopentyl glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol having a molecular weight of 300 to 1000, dipropylene glycol, tripropylene glycol, bishydroxyethoxybenzene, 1,4-cyclohexanedimethanol, bisphenol A, bisphenol S, hydrogenated bisphenol A, hydroquinone or diol components thereof such as alkylene oxide adducts and dimer acids, succinic acid, adipic acid, nonanediol, and the like. Polyester polyols obtained by dehydration condensation reaction of dicarboxylic acid components such as dicarboxylic acid, sebacic acid, dodecanedicarboxylic acid, maleic anhydride, fumaric acid, 1,3-cyclopentanedicarboxylic acid, terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalenedicarboxylic acid, 2,5-naphthalenedicarboxylic acid, 2,6-naphthalenedicarboxylic acid, naphthalenedicarboxylic acid, biphenyldicarboxylic acid, 1,2-bisphenoxyethane-p,p'-dicarboxylic acid, anhydrides or ester-forming derivatives of dicarboxylic acids, polyester polyols obtained by ring-opening polymerization of cyclic ester compounds such as ε-caprolactone, and polyester polyols obtained by copolymerization of these.

[0035] The polycarbonate polyol is not particularly limited, and examples thereof include polycarbonate polyols obtained by reacting diols such as 1,3-propylene glycol, 1,4-butylene glycol, 2-methyl-1,3-propylene glycol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 1,8-octanediol, 1,10-decanediol, and diethylene glycol with diphenyl carbonate, phosgene, etc. The weight average molecular weight of such polycarbonate polyols is not particularly limited, but is preferably 500 to 3000, and more preferably 800 to 2500, from the viewpoint of the handling properties of the polycarbonate polyol and the bending resistance of the obtained leather.

[0036] The low molecular weight diol is not particularly limited, and examples thereof include ethylene glycol, propylene glycol, diethylene glycol, 1,4-butanediol, 1,6-hexanediol, nonanediol, and neopentyl glycol.

[0037] The above-mentioned (b2) polyol is not particularly limited, and examples thereof include trimethylolpropane, pentaerythritol, sorbitol and other trivalent or higher low molecular weight polyols. In addition, compounds having a molecular weight of 500 or less, which are obtained by adding one or more alkylene oxides to such trivalent or higher low molecular weight polyols or low molecular weight polyalkylene polyamines, can also be used as the above-mentioned (b2) polyol. Examples of the above-mentioned low molecular weight polyalkylene polyamines include ethylenediamine, diethylenetriamine, triethylenetetramine and the like. Examples of the above-mentioned alkylene oxides include ethylene oxide, propylene oxide, butylene oxide and the like. Among such (b2) polyols, from the viewpoint of the wear resistance and bending resistance of the leather, trivalent to tetravalent (b2) polyols are preferred, and trivalent (b2) polyols are more preferred.

[0038] In the above-mentioned polyurethane resin, when the above-mentioned (b2) polyol is used, from the viewpoint of the wear resistance and bending resistance of the leather, the proportion of the above-mentioned (b2) polyol is preferably 0.1 to 1.5 mass %, more preferably 0.3 to 1.1 mass % relative to the total amount of the above-mentioned (b1) polyol, the above-mentioned (b2) polyol and the (c) compound having an anionic hydrophilic group and at least two active hydrogen atoms.

[0039] (c) A compound having an anionic hydrophilic group and at least two active hydrogen atoms

[0040] As the above-mentioned (c) compound having anionic hydrophilic groups and at least two active hydrogens, there is no particular restriction, for example, a compound having anionic hydrophilic groups such as carboxyl groups, carboxylate groups, sulfonic groups, sulfonic acid ester groups and groups containing active hydrogens such as two or more hydroxyl groups. By copolymerizing the compound (c) having anionic hydrophilic groups and at least two active hydrogens, a self-emulsifying waterborne polyurethane resin can be obtained. As the above-mentioned (c) compound, for example, 2,2-dimethylol propionic acid, 2,2-dimethylol butyric acid, 2,2-dimethylol butyric acid, 2,2-dimethylol valeric acid, dihydroxy maleic acid, 2,6-dihydroxybenzoic acid, etc. These (c) compounds can be used alone or in combination of two or more.

[0041] The content of the anionic hydrophilic group in the obtained self-emulsifying aqueous polyurethane resin is preferably 0.3 to 3.0% by mass, more preferably 0.5 to 2.5% by mass, from the viewpoint of emulsification stability, storage stability and flex resistance of leather.

[0042] (d) Polyamine

[0043] The above-mentioned (d) polyamine is a compound having two or more amino groups and / or imino groups in one molecule. Such (d) polyamines are not particularly limited, and examples thereof include diamines such as ethylenediamine, propylenediamine, tetramethylenediamine, hexamethylenediamine, diaminocyclohexylmethane, hydrazine, 2-methylpiperazine, isophoronediamine, norbornanediamine, diaminodiphenylmethane, toluenediamine, and xylylenediamine; polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and iminobispropylamine; amidoamines derived from diprimary amines and monocarboxylic acids; water-soluble amine derivatives such as monoketimines of diprimary amines; and hydrazine derivatives such as oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide, 1,1'-ethylenehydrazide, 1,1'-trimethylenehydrazide, and 1,1'-(1,4-butylene)dihydrazide. These (d) polyamines may be used alone or in combination of two or more. The amount of the (d) polyamine used is preferably an amount containing 0.8 to 1.2 equivalents of amino groups, etc., relative to the free isocyanate groups of the isocyanate group-terminated prepolymer described below.

[0044] (isocyanate terminated prepolymer)

[0045] The isocyanate-terminated prepolymer is a reaction product of the (a) organic polyisocyanate, the (b) polyol, and the (c) compound having an anionic hydrophilic group and at least two active hydrogen atoms.

[0046] The method for producing such isocyanate-terminated prepolymers is not particularly limited, and examples thereof include the so-called one-step method and the multi-stage isocyanate polyaddition reaction method of the known single-stage type. As the reaction temperature, it is preferably 40 to 150° C. At this time, reaction catalysts such as dibutyltin dilaurate, stannous octoate, dibutyltin di-2-ethylhexanoate, triethylamine, triethylenediamine, N-methylmorpholine, tri(2-ethylhexanoate) bismuth, or reaction inhibitors such as phosphoric acid, sodium hydrogen phosphate, p-toluenesulfonic acid, adipic acid, and benzoyl chloride may be added as needed.

[0047] In addition, an organic solvent that does not react with isocyanate groups may be added during or after the reaction. Examples of such organic solvents include acetone, methyl ethyl ketone, methyl isobutyl ketone, tetrahydrofuran, dioxane, dimethylformamide, dimethyl sulfoxide, toluene, xylene, ethyl acetate, butyl acetate, and dichloromethane. Among these organic solvents, methyl ethyl ketone, toluene, and ethyl acetate are particularly preferred. In addition, these organic solvents may be removed by heating and reducing pressure after the emulsification and dispersion of the prepolymer and the chain growth.

[0048] When the isocyanate-terminated prepolymer is produced, the molar ratio of the isocyanate group to the hydroxyl group (NCO / OH) of the raw material is preferably 2.0 / 1.0 to 1.1 / 1.0, and more preferably 1.7 / 1.0 to 1.25 / 1.0. By adjusting the molar ratio of the isocyanate group to the hydroxyl group of the raw material to within the above range, an isocyanate-terminated prepolymer having a desired free isocyanate group content can be obtained. On the one hand, when the molar ratio of the isocyanate group to the hydroxyl group of the raw material is lower than the above lower limit, the content of the free isocyanate group tends to be excessively reduced, and on the other hand, when it exceeds the above upper limit, the content of the free isocyanate group tends to be excessively increased.

[0049] The content of free isocyanate groups in the isocyanate-terminated prepolymer thus obtained is preferably 0.2 to 3.0% by mass. When the free isocyanate group content is lower than the lower limit, the viscosity of the isocyanate-terminated prepolymer during manufacture tends to increase significantly, requiring a large amount of organic solvent, which is disadvantageous in cost and tends to make emulsification and dispersion difficult. On the other hand, when the free isocyanate group content exceeds the upper limit, the balance of water solubility after emulsification and dispersion and after chain growth using (d) polyamine tends to change significantly, and there is a situation where the storage stability or processing stability of the waterborne polyurethane resin over time is reduced. In addition, the bending resistance of the leather may be reduced.

[0050] It should be noted that the above-mentioned (a) organic polyisocyanate, the above-mentioned (b) polyol and the above-mentioned (c) compound having an anionic hydrophilic group and at least two active hydrogen atoms all have multiple reaction sites, and the above-mentioned isocyanate group-terminated prepolymer obtained by reacting such (a) organic polyisocyanate, (b) polyol and (c) compound having anionic hydrophilic group and at least two active hydrogen atoms has a complex structure and cannot be directly represented by a general formula (structural formula).

[0051] (Neutralized product of isocyanate-terminated prepolymer)

[0052] The neutralized product of the isocyanate-terminated prepolymer is obtained by neutralizing the anionic hydrophilic groups in the isocyanate-terminated prepolymer. Such a neutralized product of the isocyanate-terminated prepolymer can be produced by (i) neutralizing the anionic hydrophilic groups in the isocyanate-terminated prepolymer obtained by reacting the (a) organic polyisocyanate, the (b) polyol and the (c) compound having anionic hydrophilic groups and at least two active hydrogen atoms by a known method, or (ii) mixing the (a) organic polyisocyanate, the (b) polyol and the (c) compound having anionic hydrophilic groups and at least two active hydrogen atoms, neutralizing the anionic hydrophilic groups in the (c) compound by a known method, and then reacting the neutralized (c) compound, the (a) organic polyisocyanate and the (b) polyol. The neutralized product of the isocyanate group-terminated prepolymer can also be produced by (iii) reacting the (a) organic polyisocyanate, the (b) polyol, and the (c) compound in which the anionic hydrophilic group is a salt of anionic hydrophilic groups.

[0053] In the production methods (i) and (ii) above, the basic compound used for neutralization of the anionic hydrophilic group is not particularly limited, and examples thereof include amines such as trimethylamine, triethylamine, tri-n-propylamine, tributylamine, N-methyldiethanolamine, N,N-dimethylmonoethanolamine, N,N-diethylmonoethanolamine, and triethanolamine; alkali metal hydroxides such as potassium hydroxide and sodium hydroxide; ammonia, etc. Among them, tertiary amines such as trimethylamine, triethylamine, tri-n-propylamine, and tributylamine are particularly preferred.

[0054] When the anionic hydrophilic groups in the manufacturing methods (i) and (ii) are neutralized, the amount of the neutralizing alkaline compound used is preferably 0.5 to 1.5 equivalents, more preferably 0.6 to 1.4 equivalents, and particularly preferably 0.7 to 1.3 equivalents relative to the anionic hydrophilic groups. When the amount of the neutralizing alkaline compound used is less than the lower limit, the emulsification and storage stability of the aqueous polyurethane resin tend to decrease. On the other hand, even if the neutralizing alkaline compound is added in an amount exceeding the upper limit, the emulsification and storage stability of the aqueous polyurethane resin will not be further improved, and therefore, it is not economically preferred.

[0055] (Waterborne polyurethane resin)

[0056] The self-emulsifying aqueous polyurethane resin is obtained by chain-extending the neutralized product of the isocyanate group-terminated prepolymer using the (d) polyamine (chain-extended product).

[0057] (Emulsification and dispersion)

[0058] When the neutralized product of the above-mentioned isocyanate-terminated prepolymer chain grows, first, the above-mentioned neutralized product of the isocyanate-terminated prepolymer is emulsified and dispersed in water. There is no particular limitation on the method of emulsification and dispersion, and examples thereof include conventionally known methods using a homomixer, a homogenizer, a disperser, and the like. The above-mentioned neutralized product of the isocyanate-terminated prepolymer can be emulsified and dispersed in water at a temperature in the range of 0 to 40° C. even without the addition of an emulsifier. Thus, the reaction between the isocyanate group and water can be suppressed. In addition, when the above-mentioned neutralized product of the isocyanate-terminated prepolymer is emulsified and dispersed, a reaction inhibitor such as phosphoric acid, sodium dihydrogen phosphate, disodium hydrogen phosphate, p-toluenesulfonic acid, adipic acid, benzoyl chloride, etc. can also be added as needed.

[0059] (Chain Growth)

[0060] Next, the neutralized isocyanate group-terminated prepolymer emulsified and dispersed in water is chain-extended using the polyamine (d) to form the self-emulsifying aqueous polyurethane resin.

[0061] The chain growth method is not particularly limited, but preferably includes, for example, a method in which the (d) polyamine is added to an emulsified dispersion of the neutralized isocyanate-terminated prepolymer to carry out chain growth, or a method in which the emulsified dispersion of the neutralized isocyanate-terminated prepolymer is added to the (d) polyamine to carry out chain growth. The reaction of the neutralized isocyanate-terminated prepolymer with the amine is usually completed within 30 to 120 minutes after the neutralized isocyanate-terminated prepolymer and the (d) polyamine are mixed at a reaction temperature of 20 to 50°C.

[0062] Such chain extension may be carried out simultaneously with the emulsification and dispersion, after the emulsification and dispersion, or before the emulsification and dispersion. When the obtained aqueous polyurethane resin contains an organic solvent, the organic solvent is preferably removed at a temperature of 30 to 80° C. under reduced pressure.

[0063] It should be noted that, similar to the above-mentioned (a) organic polyisocyanate, the above-mentioned (b) polyol and the above-mentioned (c) compound having an anionic hydrophilic group and at least two active hydrogen atoms, the above-mentioned (d) polyamine also has a plurality of reaction sites, and the chain-extended product of the above-mentioned neutralized product of the isocyanate group-terminated prepolymer obtained by chain-extending the neutralized product of the above-mentioned isocyanate group-terminated prepolymer using such (d) polyamine (self-emulsifying waterborne polyurethane resin) has a complex structure similar to the above-mentioned isocyanate group-terminated prepolymer and cannot be directly represented by a general formula (structural formula).

[0064] The self-emulsifying aqueous polyurethane resin thus obtained is preferably used in a state of being emulsified and dispersed in water, and its resin component concentration is not particularly limited, but is preferably 20 to 60% by mass. The resin component concentration in the aqueous emulsified dispersion of the self-emulsifying aqueous polyurethane resin can be adjusted by adding or removing water.

[0065] (Acrylic resin)

[0066] As the above-mentioned acrylic resin, homopolymers and copolymers of acrylic monomers can be mentioned. As the above-mentioned acrylic monomers, (meth) methyl acrylate, (meth) ethyl acrylate, (meth) 2-ethylhexyl acrylate, (meth) lauryl acrylate, (meth) stearyl acrylate, (meth) cyclohexyl acrylate, (meth) isobornyl acrylate, (meth) benzyl acrylate, (meth) acrylic acid, (meth) glycidyl acrylate, (meth) dimethylaminoethyl acrylate, (meth) diethylaminoethyl acrylate, (meth) 2-hydroxyethyl acrylate, (meth) 2-hydroxypropyl acrylate and (meth) acrylic acid and derivatives thereof can be mentioned. Here, (meth) acrylic acid represents acrylic acid or methacrylic acid. In addition, these acrylic monomers can be used alone or in combination of two or more.

[0067] Examples of the comonomers used in the acrylic resins include aromatic vinyl compounds such as styrene, α-methylstyrene, and p-methylstyrene; acrylamides such as acrylamide, diacetone acrylamide, methacrylamide, and maleamide; heterocyclic vinyl compounds such as vinyl pyrrolidone; vinyl compounds such as vinyl chloride, acrylonitrile, vinyl ether, vinyl ketone, and vinylamide; α-olefins such as ethylene and propylene; maleic acid, fumaric acid, itaconic acid, and derivatives thereof, etc. These comonomers may be used alone or in combination of two or more.

[0068] The glass transition temperature (Tg) of the acrylic resin is preferably -40 to +50° C., more preferably -20 to +30° C., and most preferably -10 to +20° C. When the Tg of the acrylic resin is less than the above lower limit, the abrasion resistance and antifouling performance of the leather tend to decrease, while when the Tg exceeds the above upper limit, the abrasion resistance and antifouling performance of the leather tend to increase, but the bending resistance tends to decrease.

[0069] In the surface treatment agent of the present invention, as the acrylic resin, a commercially available acrylic resin can be used. Examples of commercially available acrylic resins include Cybinol EC-065 (Tg = 5°C), Cybinol EC-071 (Tg = -20°C), Cybinol EC-064 (Tg = -40°C), Cybinol UC-6600 (Tg = 50°C), Cybinol EC-2020 (Tg = 17°C) (all manufactured by Saiden Chemical Industry Co., Ltd.), DURAFLEX 84S (Tg = 0°C), ORGAL P036V (Tg = 0°C), ORGAL D55HC (Tg = -3°C), ORGAL DCS80 (Tg = -16°C) (all manufactured by ORGANIK KIMYA Co., Ltd.), TOCRYL BCX-8111 (Tg = -30°C), TOCRYL W-168 (Tg = -10°C), TOCRYL X-4403 (Tg = -7°C), TOCRYL W463 (Tg = 11°C), TOCRYL BCX-1160R-2 (Tg = 12°C), TOCRYL BCX-8104 (Tg = 29°C), TOCRYL X-4402 (Tg = 35°C) (all manufactured by Toyochem Co., Ltd.).

[0070] (B) Compound

[0071] The (B) compound used in the present invention is a compound having two or more active hydrogens in one molecule. As such (B) compounds having two or more active hydrogens in one molecule (hereinafter also referred to as "(B) compounds"), for example, compounds having two or more hydroxyl groups in one molecule (polyols, polyphenols, etc.), compounds having two or more amino groups in one molecule (polyamines, etc.) can be cited. In addition, in the present invention, compounds having alkylene oxide added to compounds having two or more active hydrogens in one molecule such as polyols, polyphenols, amines, polycarboxylic acids, phosphoric acid, etc. can also be used as the above-mentioned (B) compounds. Furthermore, water-soluble polymers such as polyvinyl alcohol, carboxymethyl cellulose, xanthan gum, starch, etc. can also be used as the above-mentioned (B) compounds. Such (B) compounds having two or more active hydrogens in one molecule can be used alone or in combination of two or more. In addition, among such (B) compounds having two or more active hydrogen atoms in one molecule, compounds having three or more (more preferably four or more, further preferably five or more, particularly preferably six or more) hydroxyl groups in one molecule (particularly glycerol compounds (glycerol and polyglycerol)) are preferred from the viewpoint of being able to sufficiently suppress yellowing of the leather surface.

[0072] (Polyol)

[0073] Examples of the polyol include diols having 2 to 20 carbon atoms (aliphatic diols, alicyclic diols, etc.), triols having 3 to 20 carbon atoms (aliphatic triols, etc.), and tetravalent or higher (preferably 4-8-valent) polyols having 5 to 20 carbon atoms (aliphatic polyols, sugars and their derivatives, etc.). These polyols may be used alone or in combination of two or more.

[0074] Examples of the aliphatic diols include alkylene glycols such as ethylene glycol, propylene glycol, 1,3- or 1,4-butanediol, 1,6-hexanediol, and neopentyl glycol. Examples of the alicyclic diols include cycloalkylene glycols such as cyclohexanediol and cyclohexanedimethanol. Examples of the aliphatic triols include alkane triols such as glycerol, trimethylolpropane, trimethylolethane, and hexanetriol. Examples of the aliphatic polyols include alkane polyols such as pentaerythritol, sorbitol, mannitol, and sorbitan, and their intramolecular or intermolecular dehydrates (e.g., dipentaerythritol); and intramolecular or intermolecular dehydrates of the alkane triols (e.g., polyglycerols such as diglycerol, triglycerol, tetraglycerol, pentaglycerol, hexaglycerol, and decaglycerol). Examples of the sugars include sucrose, glucose, mannose, fructose, and methyl glucoside.

[0075] (Glycerol compounds)

[0076] The glycerol-based compound (glycerol and polyglycerol) is a compound represented by the following formula (1).

[0077]

[0078] [In the formula, n is an integer from 1 to 20.]

[0079] Among these glycerol compounds, polyglycerols in which n in the above formula (1) is 2 to 20 are preferred from the viewpoint of being able to sufficiently suppress yellowing of the leather surface, polyglycerols in which n in the above formula (1) is 3 to 20 are more preferred, and polyglycerols in which n in the above formula (1) is 4 to 20 are further preferred. In addition, the upper limit of n in the above formula (1) is preferably 10 or less from the viewpoint of the texture and stability of the processing fluid.

[0080] In addition, in the present invention, the average degree of polymerization of polyglycerol is preferably 1 to 10, and more preferably 2 to 10, from the viewpoint of the performance of suppressing yellowing of the leather surface. It should be noted that the "average degree of polymerization of polyglycerol" refers to the value calculated from the hydroxyl value of polyglycerol (including a mixture of glycerol and polyglycerol) obtained by the end group analysis method. Specifically, first, in the end group analysis method, the amount of acetic acid required to acetylate the free hydroxyl groups contained in polyglycerol (including a mixture of glycerol and polyglycerol) is obtained, and then the amount of calcium hydroxide required to neutralize the amount of acetic acid is obtained. The amount of calcium hydroxide is the hydroxyl value of polyglycerol (including a mixture of glycerol and polyglycerol) [unit: mgKOH / g], and the average degree of polymerization Xn of polyglycerol (including a mixture of glycerol and polyglycerol) is calculated by the following formulas (I) and (II) using this hydroxyl value.

[0081] Molecular weight = 74 × Xn + 18 (I)

[0082] Hydroxyl value = 56110 × (Xn + 2) / molecular weight (II)

[0083] In addition, the average degree of polymerization in the case of only glycerol can also be calculated by the above method and is 1.

[0084] In the present invention, as the polyglycerol, a synthetic product that is appropriately synthesized can be used, or commercially available polyglycerol can be used. Examples of commercially available polyglycerol include diglycerol S, polyglycerol #310, polyglycerol #500, and polyglycerol #750 (the above are trade names, manufactured by Sakamoto Pharmaceutical Industry Co., Ltd.).

[0085] (Polyphenols)

[0086] Examples of the polyphenols include monocyclic polyphenols such as pyrogallol, hydroquinone, and phloroglucinol; bisphenols such as bisphenol A, bisphenol F, and bisphenol sulfone; condensates of phenol and formaldehyde (novolac), etc. These polyphenols may be used alone or in combination of two or more.

[0087] (Polyamine)

[0088] The polyamine is a compound having two or more amino groups and / or imino groups in one molecule. Such polyamines are not particularly limited, and examples thereof include diamines such as ethylenediamine, propylenediamine, tetramethylenediamine, hexamethylenediamine, diaminocyclohexylmethane, hydrazine, 2-methylpiperazine, isophoronediamine, norbornanediamine, diaminodiphenylmethane, toluenediamine, and xylenediamine; polyamines such as diethylenetriamine, triethylenetetramine, tetraethylenepentamine, and iminobispropylamine; amideamines derived from diprimary amines and monocarboxylic acids; water-soluble amine derivatives such as monoketimines of diprimary amines; and hydrazine derivatives such as oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, itaconic acid dihydrazide, 1,1'-ethylenehydrazide, 1,1'-trimethylenehydrazide, and 1,1'-(1,4-butylene)dihydrazide. These polyamines may be used alone or in combination of two or more.

[0089] <Surface treatment agent>

[0090] The surface treatment agent of the present invention comprises the above-mentioned (A) resin capable of forming a resin layer on the surface of a leather substrate and the above-mentioned (B) compound having two or more active hydrogen atoms in one molecule. By treating the surface of the leather substrate with such a surface treatment agent, a surface treatment layer is formed on the surface of the leather substrate using the surface treatment agent, and even if the leather substrate can yellow, the surface treatment layer can suppress the yellowing of the leather surface.

[0091] In the surface treatment agent of the present invention, the mass ratio of the above-mentioned (A) resin and the above-mentioned (B) compound can be appropriately set according to the degree of yellowing of the leather surface. Generally, the content of the above-mentioned (B) compound is preferably 0.1 to 50 parts by mass, and more preferably 1 to 10 parts by mass, relative to 100 parts by mass of the above-mentioned (A) resin. When the content of the above-mentioned (B) compound is less than the above-mentioned lower limit, the yellowing of the leather surface tends to be unable to be fully suppressed; on the other hand, when the content of the above-mentioned (B) compound exceeds the above-mentioned upper limit, the quality of the leather surface tends to be reduced (for example, a sticky feeling is exhibited and the touch is reduced).

[0092] In addition, in addition to the above-mentioned (A) resin and (B) compound, the surface treatment agent of the present invention may also contain various additives such as fluorine-containing compounds, hydrophilic compounds, matting agents, smoothing agents, thickeners, crosslinking agents, antifouling agents, surfactants, defoaming agents, leveling agents, viscoelasticity regulators, wetting agents, dispersants, preservatives, film-forming agents, plasticizers, penetrants, fragrances, bactericides, acaricides, mildewicides, ultraviolet absorbers, antioxidants, antistatic agents, flame retardants, dyes, pigments, and reaction catalysts, etc., within the scope that does not impair the purpose and performance of the present invention.

[0093] (Fluorinated compounds)

[0094] In the surface treatment agent of the present invention, a fluorine-containing compound may be added to impart SG performance (soil guard: performance that makes it difficult for dirt to adhere) to the leather surface. Such fluorine-containing compounds are not particularly limited as long as they are compounds having a fluorine-containing hydrocarbon group (e.g., a fluoroalkyl group (preferably having 1 to 6 carbon atoms), a fluoroalkenyl group (preferably having 2 to 6 carbon atoms), preferably a perfluoroalkyl group (more preferably having 1 to 6 carbon atoms), a perfluoroalkenyl group (more preferably having 2 to 6 carbon atoms)). Preferably, the fluorine-containing polymer is a fluorine-containing polymer containing repeating units derived from the above-mentioned fluorine-containing hydrocarbon group-containing fluorine-containing monomer. The above-mentioned fluorine-containing polymer may be a homopolymer of the above-mentioned fluorine-containing monomer or a copolymer. The copolymer of the above-mentioned fluorine-containing monomer may be a copolymer of two or more of the above-mentioned fluorine-containing monomers or a copolymer of one or more of the above-mentioned fluorine-containing monomers and one or more of the non-fluorine-containing monomers.

[0095] The content of such a fluorine-containing compound is preferably 10 to 100 parts by mass, more preferably 30 to 70 parts by mass, based on 100 parts by mass of the resin (A), from the viewpoint of SG performance.

[0096] The fluorine-containing compound is a compound having a water repellency of grade 3 or higher in the following water repellency test.

[0097] <Waterproof test>

[0098] The aqueous solution in which the adhesion amount of the above-mentioned fluorine-containing compound was adjusted to 10 mass % was used to dye 100% polyester cloth (weight 100 g / m 2 ) was immersed in water (absorption rate 60%), dried at 130°C for 1 minute, and then heat treated at 180°C for 30 seconds. Then, the treated cloth was subjected to a waterproof test according to the method described in the waterproof test (spray test) of JIS L1092 (2009) 7.2, and the waterproof performance of the treated cloth was evaluated according to the following standards.

[0099] (Waterproof performance evaluation standard)

[0100] Level 5: The surface of the treated cloth is not wet and no water droplets are attached.

[0101] Grade 4: The surface of the treated cloth showed a little moisture and attachment of water droplets.

[0102] Grade 3: The surface of the treated cloth appears partially wet.

[0103] Grade 2: The surface of the treated cloth appears wet.

[0104] Grade 1: The surface and back of the treated cloth appear completely wet.

[0105] As the fluorine-based monomer, a monomer having the fluorine-containing hydrocarbon group and a polymerizable functional group is preferred, and as the polymerizable functional group, an acrylic group, a methacrylic group, or an α-substituted acrylic group is preferred. It should be noted that the α-substituted acrylic group refers to a group in which the hydrogen atom bonded to the carbon atom at the α position of the acrylic group is substituted by a halogen atom, a cyano group, a trifluoromethyl group, or the like.

[0106] As such a fluorine-based monomer, a compound represented by the following formula (2) is preferred.

[0107] CH 2 =C(-X)-C(=O)-YZR f (2)

[0108] In the above formula (2), X represents a hydrogen atom, a halogen atom (preferably a fluorine atom, a chlorine atom, a bromine atom, an iodine atom) or a monovalent organic group; as the above monovalent organic group, preferably a linear or branched alkyl group having 1 to 21 carbon atoms (more preferably 1 to 10 carbon atoms, and further preferably 1 to 5 carbon atoms), -CFX 1 X 2 Base (X 1 and X 2 X represents a hydrogen atom or a halogen atom (more preferably a fluorine atom, a chlorine atom, a bromine atom, or an iodine atom), a cyano group, a linear or branched fluoroalkyl group having 1 to 21 carbon atoms (more preferably 1 to 10 carbon atoms, and further preferably 1 to 5 carbon atoms), a substituted or unsubstituted benzyl group, or a substituted or unsubstituted phenyl group. Among them, X is preferably a hydrogen atom, a fluorine atom, a chlorine atom, a bromine atom, an iodine atom, a methyl group, a cyano group, or a trifluoromethyl group, and more preferably a chlorine atom.

[0109] Y represents -O- or -NH-, and is preferably -O-.

[0110] Z represents a direct bond or a divalent organic group, and the divalent organic group is preferably a linear or branched divalent aliphatic group (more preferably a saturated aliphatic group) having 1 to 20 carbon atoms (more preferably 1 to 10 carbon atoms, further preferably 1 to 4 carbon atoms, and particularly preferably 1 to 2 carbon atoms), a divalent substituted or unsubstituted aromatic group having 6 to 18 carbon atoms (more preferably 6 to 12 carbon atoms), a divalent substituted or unsubstituted cyclic aliphatic group having 3 to 18 carbon atoms (more preferably 6 to 18 carbon atoms, further preferably 6 to 12 carbon atoms), -R 1 N(R 2 )-Z 1 -Base (R 1 represents a linear or branched alkylene group having 1 to 10 carbon atoms (more preferably 1 to 4 carbon atoms, and even more preferably 1 to 2 carbon atoms), R 2 represents a linear or branched alkyl group having 1 to 10 carbon atoms (more preferably 1 to 4 carbon atoms), and Z 1 Indicates -SO 2 - or -C(=O)-), -CH 2 CH(OZ 2 )CH 2 -(Ar-O) p -Base(Z 2 represents a hydrogen atom or an acyl group having 1 to 10 carbon atoms (more preferably 1 to 4 carbon atoms) (formyl, acetyl, etc.), Ar represents a substituted or unsubstituted arylene group having 6 to 18 carbon atoms (more preferably 6 to 12 carbon atoms), and p is 0 or 1), -(CH 2 ) n -Ar-(O) q -yl (Ar represents a substituted or unsubstituted arylene group having 6 to 18 carbon atoms (more preferably 6 to 12 carbon atoms), n is an integer of 0 to 10 (more preferably 0 to 5), and q is 0 or 1), -(CH 2 ) m -Z 3 -(CH 2 ) n -Base(Z 3 Indicates -SO 2- or -S-, m is an integer of 1 to 10 (more preferably 1 to 5), and n is an integer of 0 to 10 (more preferably 0 to 5). Among them, Z is more preferably a linear or branched divalent aliphatic group (more preferably a saturated aliphatic group) having 1 to 10 carbon atoms (more preferably 1 to 4 carbon atoms, particularly preferably 1 to 2 carbon atoms), a divalent substituted or unsubstituted aromatic group having 6 to 18 carbon atoms (more preferably 6 to 12 carbon atoms), a divalent substituted or unsubstituted cyclic aliphatic group having 6 to 18 carbon atoms (more preferably 6 to 12 carbon atoms), -CH 2 CH 2 N(R 2 )-SO 2 -Base (R 2 represents a linear or branched alkyl group having 1 to 4 carbon atoms, -CH 2 CH(OZ 2 )CH 2 -(Ph-O) p -Base(Z 2 represents a hydrogen atom or an acetyl group, Ph represents a phenylene group, and p is 0 or 1), -(CH 2 ) n -Ph-O- group (Ph represents a phenylene group, and n is an integer of 0 to 10 (more preferably 0 to 5)), -(CH 2 ) m -Z 3 -(CH 2 ) n -Base(Z 3 Indicates -SO 2 - or -S-, m is an integer of 1 to 10 (more preferably 1 to 5), and n is an integer of 0 to 10 (more preferably 0 to 5).

[0111] R f It represents a linear or branched fluoroalkyl group (preferably a perfluoroalkyl group) having 1 to 20 carbon atoms (preferably 1 to 10 carbon atoms, more preferably 1 to 6 carbon atoms, further preferably 4 to 6 carbon atoms, and particularly preferably 6 carbon atoms).

[0112] The non-fluorine-based monomer is a monomer having a polymerizable functional group that does not contain a fluorine atom, and the polymerizable functional group is preferably a functional group having an ethylenically unsaturated double bond such as an acrylic group, a methacrylic group, an α-substituted acrylic group, etc. It should be noted that the α-substituted acrylic group refers to a group in which the hydrogen atom bonded to the carbon atom at the α position of the acrylic group is substituted by a halogen atom other than a fluorine atom, a cyano group, etc.

[0113] In the surface treatment agent of the present invention, as the above-mentioned fluorine-containing compound, a commercially available fluorine-containing compound can be used. Examples of the commercially available fluorine-containing compound include NK Guard S-0671, NK Guard S-0521, NK Guard S-05, NK Guard S-0543, NK Guard S-740, NK Guard S-0546, NK Guard S-0545, NK Guard S-1115, NK Guard S-0672 (all manufactured by Nichika Chemical Co., Ltd.), Unidyne TG-5574, Unidyne TG-4575, Unidyne TG-5543, Unidyne TG-5546, Unidyne TG-5545, Unidyne TG-5601, Unidyne TG-5541, Unidyne TG-4571, Unidyne TG-6071, Unidyne TG-6501, Unidyne TG-5671, UnidyneTG-5672, Unidyne TG-5673, Unidyne TG-9011 (all manufactured by Daikin Industries, Ltd.), AsahiGuard AG-E060, AsahiGuard AG-E061, AsahiGuard AG-7000, AsahiGuard AG-950, AsahiGuard AG-E081, AsahiGuard AG-E082, AsahiGuard AG-E092, AsahiGuard AG-E500D (all manufactured by AGC Corporation), Maxguard FX-850, Maxguard FX-860, Maxguard FX-880 (all manufactured by Kyogen Chemical Co., Ltd.), Paraguard AF660 (manufactured by Ohara Paragium Chemical Co., Ltd.), NUVA2114 (Clariant Japan Ltd.), Scotchgard PM3622, Scotchgard PM490, Scotchgard PM930 (all manufactured by 3M Co., Ltd.), etc.

[0114] (Hydrophilic Compounds)

[0115] In order to impart SR performance (Soil Release: the performance that dirt can be easily removed by wiping with water, etc. even if it adheres) to the leather surface, a hydrophilic compound may be blended in the surface treatment agent of the present invention. Examples of such hydrophilic compounds include polyester hydrophilic compounds, polyurethane hydrophilic compounds other than the above-mentioned self-emulsifying aqueous polyurethane resins, silicone hydrophilic compounds, and water-soluble polymer compounds.

[0116] The content of such a hydrophilic compound is preferably 5 to 50 parts by mass, more preferably 15 to 40 parts by mass, based on 100 parts by mass of the (A) resin, from the viewpoint of SR performance.

[0117] The hydrophilic compound is a compound that is confirmed to have no residue when an aqueous solution in which the hydrophilic compound is dissolved to a concentration of 10% by mass is filtered using polyester gauze (mesh size 79 μm).

[0118] Among such hydrophilic compounds, polyester hydrophilic compounds are preferred, and hydrophilic polyester copolymers containing polycarboxylic acid component units or ester-forming derivatives thereof and polyol component units are more preferred, and it is further preferred that the hydrophilic polyester copolymer has an aromatic ring in the chain unit. Examples of the hydrophilic polyester copolymer having an aromatic ring include copolymers of aromatic polycarboxylic acids or ester-forming derivatives thereof and polyols.

[0119] Examples of the aromatic polycarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, 1,4-naphthalene dicarboxylic acid, 2,5-naphthalene dicarboxylic acid, and 2,6-naphthalene dicarboxylic acid. Examples of the ester-forming derivatives of the aromatic polycarboxylic acid include lower alkyl esters of the aromatic polycarboxylic acid (e.g., methyl ester, ethyl ester, propyl ester, dibutyl ester, etc.), salts of the aromatic polycarboxylic acid (e.g., chlorides, etc.), and phthalic anhydride.

[0120] In addition, as the above-mentioned aromatic polycarboxylic acid, an aromatic polycarboxylic acid having a sulfonate group may also be used. As the aromatic polycarboxylic acid having a sulfonate group, sulfonic acid metal salts (preferably sodium salts and potassium salts) of aromatic dicarboxylic acids having a sulfonic acid group (for example, sulfoterephthalic acid, 5-sulfoisophthalic acid, 4-sulfophthalic acid, 5-sulfoisophthalic acid, 4-sulfonaphthalene-2,7-dicarboxylic acid, 5-(4-sulfophenoxy)isophthalic acid, etc.), sulfonic acid metal salts (preferably sodium salts and potassium salts) of lower alkyl esters of aromatic dicarboxylic acids having the above-mentioned sulfonic acid groups, etc. may be mentioned.

[0121] Such aromatic polycarboxylic acids (including aromatic polycarboxylic acids having sulfonate groups) and their ester-forming derivatives may be used alone or in combination of two or more. In addition, from the viewpoint of improving the water solubility or emulsification dispersibility of the hydrophilic polyester copolymer and the antifouling performance of the leather, it is more preferred to use an aromatic polycarboxylic acid without a sulfonate group and an aromatic polycarboxylic acid having a sulfonate group in combination.

[0122] Examples of the polyol include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,4-butylene glycol, 2-methyl-1,3-propylene glycol, neopentyl glycol, 1,5-pentanediol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2,4-diethyl-1,5-pentanediol, 2-ethyl-1,3-hexanediol, 2,2-dimethyl-3-hydroxypropyl-2,2'-dimethyl-3-hydroxypropionate, 2-n-butyl-2-ethyl-1,3-propylene glycol, 3-ethyl-1,5-pentanediol, 3-propyl-1,5-pentanediol, 2,2-diethyl-1,3-propylene glycol, 3-octyl- Aliphatic diols such as 1,5-pentanediol, diethylene glycol, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, polyethylene glycol with a molecular weight of 300 to 10,000, random or block copolymers of ethylene oxide and propylene oxide; 1,3-bis(hydroxymethyl)cyclohexane, 1,4-bis(hydroxymethyl)cyclohexane, 1,4-bis(hydroxyethyl)cyclohexane, 1,4-bis(hydroxypropyl)cyclohexane, 1,4-bis(hydroxymethoxy)cyclohexane, 1,4-bis(hydroxyethoxy)cyclohexane, 2,2-bis(4-hydroxymethoxycyclohexyl)propane, 2,2-bis(4-hydroxyethoxycyclohexyl)propane, bis(4-hydroxycyclohexyl)methane, 2,2-bis(4-hydroxycyclohexyl)propane, 3(4),8(9)-tricyclo[5.2.1.0 2,6 ] alicyclic diols such as decanedimethanol; aromatic diols such as bishydroxyethoxybenzene, bisphenol A, bisphenol S, hydroquinone; and adducts of these alkylene oxides. These polyols can be used alone or in combination of two or more. In addition, among these polyols, diols having oxyethylene such as polyethylene glycol are preferred from the viewpoint of the time-dependent stability of the emulsified dispersion of the hydrophilic polyester copolymer.

[0123] The weight average molecular weight of the polyester hydrophilic compound is preferably 1000 to 200000, more preferably 10000 to 50000. When the weight average molecular weight of the polyester hydrophilic compound is less than the above lower limit, the SR performance of the leather may not be fully exerted, while when it exceeds the above upper limit, the viscosity of the polyester hydrophilic compound may become too high, making it difficult to easily handle.

[0124] In the surface treatment agent of the present invention, as the hydrophilic compound, a commercially available hydrophilic compound can be used. Examples of commercially available hydrophilic compounds include NICEPOLE PR-99, NICEPOLE PR-9000, NICEPOLE PRK-60 (all manufactured by Nikka Chemical Co., Ltd.), Hydroperm NIOPOs (manufactured by Archroma), and the like.

[0125] (Matting agent)

[0126] In order to adjust the glossiness and glossiness of the leather surface, a matting agent may be added to the surface treatment agent of the present invention. Examples of such matting agents include organic beads, silica particles, talc, aluminum hydroxide, calcium sulfate, calcium silicate, calcium carbonate, magnesium carbonate, barium carbonate, aluminum silicate, kaolin, mica, and mica. These matting agents may be used alone or in combination of two or more.

[0127] Examples of the organic beads include polyurethane beads, acrylic beads, silicone beads, olefin beads, high-density polyethylene, and low-density polyethylene. In addition, examples of the silica particles include dry silica and wet silica. Among them, dry silica is preferred from the viewpoint of high scattering effect and ability to adjust the gloss value with a small amount. The average particle size (average secondary particle size) of dry silica is preferably 4 to 15 μm, and more preferably 5 to 12 μm.

[0128] The content of such a matting agent can be appropriately used according to the matte feeling (glossiness and glossiness) of the leather surface, and is usually preferably 1 to 150 parts by mass, more preferably 5 to 120 parts by mass, and further preferably 7 to 100 parts by mass, relative to 100 parts by mass of the above-mentioned (A) resin.

[0129] (Smoothing Agent)

[0130] In order to improve the smoothness and wear resistance of the leather surface, a smoothing agent can also be combined in the surface treatment agent of the present invention. As this type of smoothing agent, for example, polydimethylsilicone, hydrogen-modified silicone, vinyl-modified silicone, epoxy-modified silicone, amino-modified silicone, carboxyl-modified silicone, halogen-modified silicone, methacryloxy-modified silicone, mercapto-modified silicone, fluorine-modified silicone, alkyl-modified silicone, phenyl-modified silicone, polyether-modified silicone, etc. can be cited. These smoothing agents can be used alone or in combination of two or more. In addition, among these smoothing agents, polydimethylsilicone and epoxy-modified silicone are preferably used from the viewpoint of the large effect of improving wear resistance.

[0131] In the surface treatment agent of the present invention, commercial products can be used as such smoothing agents. Commercial products of the emulsion of the above-mentioned polydimethylsilicone include, for example, DOWSIL SM490EX, DOWSIL SM-8706EX, DOWSIL IE-7046T, DOWSIL FBL-3289, DOWSIL Q2-3238 (all manufactured by Dow Toray Co., Ltd.), KM-752T, KM-862T, KM-9737A, POLON MF-33 (all manufactured by Shin-Etsu Chemical Co., Ltd.). In addition, commercial products of the emulsion of the above-mentioned epoxy-modified silicone include, for example, DOWSIL SM-8701 (manufactured by Dow Toray Co., Ltd.), POLON MF-18T, and X-51-1264 (manufactured by Shin-Etsu Chemical Co., Ltd.).

[0132] The content of such smoothing agent (content of non-volatile components) can be used in an appropriate amount according to the smoothness and wear resistance of the leather surface. It is usually preferably 1 to 150 parts by mass, more preferably 5 to 120 parts by mass, and further preferably 7 to 100 parts by mass, relative to 100 parts by mass of the above-mentioned (A) resin.

[0133] (Thickener)

[0134] In order to adjust the viscosity to an appropriate level, a tackifier may be added to the surface treatment agent of the present invention. Examples of such tackifiers include alkali tackifying acrylic resins, associative tackifiers, and water-soluble organic polymers. These tackifiers may be used alone or in combination of two or more.

[0135] In the surface treatment agent of the present invention, a commercially available product can be used as the alkali tackifying acrylic resin. Examples of commercially available products of the alkali tackifying acrylic resin include Nikasol VT-253A (manufactured by Nippon Carbonide Industries Co., Inc.), Aron A-20P, Aron A-7150, Aron A-7070, Aron B-300, Aron B-300K, and Aron B-500 (manufactured by Toagosei Co., Ltd.), Jurymer AC-10LHP, Jurymer AC-10SHP, RHEOGIC 835H, JUNLON PW-110, and JUNLON PW-150 (manufactured by Nippon Junyaku Co., Ltd.), Primal ASE-60, Primal TT-615, and Primal RM-5 (manufactured by Rohm and Haas Japan Co., Ltd.), SN Thickener A-818 and SN Thickener A-850 (manufactured by San Nopco Co., Ltd.), and Paragum 500 (manufactured by Para-ChemSouthern Inc.), RHEOLATE 430 (manufactured by Himes Japan Co., Ltd.), Neo Sticker V-420 (manufactured by Nikka Chemical Co., Ltd.) Such alkali tackifying acrylic resins are generally sold as emulsified dispersions of the resins, and are preferably used in the emulsified dispersed state.

[0136] In the surface treatment agent of the present invention, commercial products can be used as the above-mentioned associative tackifier. Examples of commercial products of the above-mentioned associative tackifier include ADEKANOL UH-450, ADEKANOL UH-540, ADEKANOLUH-752 (all manufactured by Asahi Denka Kogyo Co., Ltd.), SN Thickener 601, SN Thickener 612, SN Thickener 621N, SN Thickener 623N, SN Thickener 660T (all manufactured by San Nopco Co., Ltd.), RHEOLATE 244, RHEOLATE 278, RHEOLATE 300 (all manufactured by Hemmings Japan Co., Ltd.), and DK Thickener SCT-275 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.).

[0137] As the water-soluble organic polymer, for example, natural water-soluble organic polymer, semi-synthetic water-soluble organic polymer, synthetic water-soluble organic polymer can be cited. As the natural water-soluble organic polymer, starches such as potato starch, sweet potato starch, wheat starch, rice starch, cassava starch, corn starch, etc.; resin polysaccharides such as gum arabic, tragacanth, karaya gum, hibiscus, etc.; seaweed polysaccharides such as sodium alginate, carrageenan, agar (galactan), sea radish, etc.; microbial fermentation polysaccharides such as xanthan gum, pullulan, curdlan, dextrin, fructan, etc.; proteins such as casein, gelatin, albumin, glue, collagen, etc.; pectin, chitin, chitosan, etc.

[0138] Examples of the semi-synthetic water-soluble organic polymer include cellulose derivatives such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, carboxymethyl cellulose, and sodium cellulose sulfate; starch derivatives such as dextrin, soluble starch, oxidized starch, carboxymethyl starch, hydroxyethyl starch, hydroxypropyl starch, dialdehyde starch, phosphate starch, and acetyl starch; and propylene glycol alginate.

[0139] Examples of the synthetic water-soluble organic polymer include polyvinyl alcohol, polyvinyl pyrrolidone, polyvinyl alkyl ether, maleic anhydride copolymer, maleic acid copolymer, maleate copolymer, and the like.

[0140] The content (non-volatile content) of such a tackifier can be appropriately used depending on the viscosity of the surface treatment agent, and is usually preferably 0.5 to 40 parts by mass, more preferably 1 to 30 parts by mass, and even more preferably 2 to 20 parts by mass, relative to 100 parts by mass of the resin (A).

[0141] (Crosslinking agent)

[0142] In order to improve the water resistance and durability of the leather, a crosslinking agent can also be used in the surface treatment agent of the present invention. As such crosslinking agents, carbodiimide crosslinking agents, isocyanate crosslinking agents, epoxy crosslinking agents, oxazoline crosslinking agents, aziridine crosslinking agents, blocked isocyanate crosslinking agents, water-dispersible isocyanate crosslinking agents, melamine crosslinking agents, etc. can be cited. These crosslinking agents can be used alone or in combination of two or more. In addition, among these crosslinking agents, from the viewpoint of the stability of the feel and the processing fluid, it is particularly preferred to use a carbodiimide crosslinking agent.

[0143] In the surface treatment agent of the present invention, commercial products can be used as such crosslinking agents. Commercial products of the above-mentioned carbodiimide crosslinking agents include, for example, Carbodilite E-02, Carbodilite SV-02, Carbodilite V02-L2, Carbodilite V-10 (all manufactured by Nisshinbo Chemical Co., Ltd.), NK Assist CI-02 (manufactured by Nikka Chemical Co., Ltd.), etc.

[0144] The content (non-volatile content) of such a crosslinking agent is preferably 1 to 15 parts by mass, more preferably 2 to 10 parts by mass, based on 100 parts by mass of the (A) resin, from the viewpoint of the wear resistance and flex resistance of the leather.

[0145] (Reaction Catalyst)

[0146] In the surface treatment agent of the present invention, in order to further suppress the yellowing of the leather surface, a carbamate reaction catalyst can also be combined. As such reaction catalysts, dibutyltin dilaurate, stannous octoate, dibutyltin di-2-ethylhexanoate, triethylamine, triethylenediamine, N-methylmorpholine, tri(2-ethylhexanoate) bismuth, etc. can be cited. These reaction catalysts can be used alone or in combination of two or more. In addition, among these reaction catalysts, from the perspective of environmental concern and suppression of yellowing, it is preferred to combine amine catalysts.

[0147] The content of such a reaction catalyst (content of nonvolatile components) is preferably 1 to 100 parts by mass, more preferably 10 to 50 parts by mass, based on 100 parts by mass of the (B) compound, from the viewpoint of suppressing yellowing of the leather surface.

[0148] [leather]

[0149] The leather of the present invention comprises a leather substrate and a surface treatment layer formed on the surface of the leather substrate. In addition, from the viewpoint of improving the adhesion of these layers, a primer layer may be provided between the leather substrate and the surface treatment layer.

[0150] (Base material for leather)

[0151] Examples of the leather substrate include synthetic leather having a surface layer made of a polyurethane resin (PU), imitation leather such as polyvinyl chloride (PVC) leather, polyurethane thermoplastic elastomer (TPU), artificial leather, and natural leather.

[0152] As the structure of the leather substrate, a fiber laminate structure having a fiber substrate and an epidermis layer can be cited. In addition, in the leather substrate of this type of structure, an adhesive layer and / or an intermediate layer can also be configured between the fiber substrate and the epidermis layer as required.

[0153] As the fiber substrate, textiles, nonwoven fabrics, knitted fabrics, etc. can be cited. As the skin layer, a polyurethane resin layer can be cited. The thickness of such skin layer is preferably 5 to 100 μm. As the adhesive layer, an adhesive layer formed using a known adhesive such as a polyurethane adhesive can be cited. The thickness of such adhesive layer is preferably 5 to 100 μm.

[0154] This type of leather substrate can be manufactured by, for example, the following method. First, a skin agent (such as a polyurethane resin) is applied to a release paper using various coating machines such as a gravure coater, a bar coater, a comma coater, a knife coater, and an air knife coater, and appropriately dried to form a skin layer. Then, an adhesive (such as a polyurethane adhesive) is applied to the skin layer using various coating machines such as a gravure coater, a bar coater, a comma coater, a knife coater, and an air knife coater, and dried to form an adhesive layer. Next, a fiber substrate is arranged on the surface of the adhesive layer for crimping, and further aging is performed. Then, by peeling off the release paper, a fiber laminate (leather substrate) having a fiber substrate, an adhesive layer, and a skin layer is obtained.

[0155] (Primer layer)

[0156] In the leather of the present invention, a primer layer can also be formed on the surface (surface of the epidermis) of the leather substrate (fiber laminate) thus prepared to improve the adhesion between the leather substrate and the surface treatment layer. The primer layer is a layer composed of resin, and known additives such as matting agent, smoothing agent, tackifier, pigment, antioxidant, etc. can also be added as needed. As a method for forming the primer layer, a method of applying primer on the surface of the leather substrate using various coating machines such as a gravure coater, a bar coater, a comma coater, a knife coater, and an air knife coater can be cited; a method of spraying primer on the surface of the leather substrate; a method of immersing the leather substrate in primer, etc.

[0157] (Surface treatment layer)

[0158] The leather of the present invention can be obtained by forming a surface treatment layer on the surface (surface of the epidermis) of the leather substrate (fiber laminate) thus produced (when the above-mentioned primer layer is formed, it is the surface of the above-mentioned primer layer). In the leather of the present invention, the above-mentioned surface treatment layer is formed using the above-mentioned surface treatment agent of the present invention. In this way, by forming the surface treatment layer on the surface of the above-mentioned leather substrate using the above-mentioned surface treatment agent of the present invention, even if the above-mentioned leather substrate is a substrate that can yellow, the yellowing of the surface of the obtained leather can be suppressed. In addition, such leather can be bonded with soft polyurethane foam by, for example, flame lamination to form a cushioning composite material, in which the yellowing of the leather surface (especially NO generated by flame lamination, etc.) can also be suppressed in the cushioning composite material. x yellowing caused by

[0159] The method for forming the surface treatment layer on the surface of the leather substrate is not particularly limited. For example, the surface treatment layer may be formed by applying the surface treatment agent on the surface of the leather substrate and then drying the surface treatment agent.

[0160] As the coating method of the surface treatment agent, for example, a method of coating the surface treatment agent on the surface of the leather substrate using various coating machines such as a gravure coater, a bar coater, a comma coater, a knife coater, and an air knife coater; a method of spraying the surface treatment agent on the surface of the leather substrate; a method of immersing the leather substrate in the surface treatment agent, etc., more preferably, a direct coating method or a reverse coating method using a gravure coater. As the coating amount of the surface treatment agent, it is preferred that the coating amount after drying is 4 to 40 g / m 2 The amount is more preferably 6 to 30 g / m 2 When the amount of coating after drying is less than the above lower limit, the wear resistance and antifouling properties of the leather may be insufficient. On the other hand, when the amount of coating after drying exceeds the above upper limit, the flexibility of the leather may be reduced.

[0161] There is no particular limitation on the method for drying the surface treatment agent after application. For example, it is preferably dried at a temperature in the range of 40 to 160° C. for 30 seconds to 10 minutes, and more preferably dried at a temperature in the range of 80 to 130° C. for 30 seconds to 2 minutes. In addition, it is preferred that an aging treatment be performed at a temperature in the range of 20 to 100° C. for 5 to 72 hours after drying.

[0162] Examples of leather products using the leather produced in this manner include vehicle interior materials, motorcycle seats and handlebars, shoes, bags, clothing, sanitary products, outdoor tents, furniture, and the like.

[0163] Example

[0164] Hereinafter, the present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited to the following Examples. It should be noted that in the synthesis examples, the content of free isocyanate groups was measured by the following method.

[0165] (Free isocyanate content)

[0166] 0.3 g of urethane prepolymer was collected into a conical flask, and 10 ml of 0.1 N dibutylamine toluene solution was added to dissolve the urethane prepolymer. Then, several drops of bromophenol blue solution were added, and the mixture was titrated with 0.1 N hydrochloric acid methanol solution to obtain the free isocyanate group content NCO% according to the following formula.

[0167] NCO% = (ab) × 0.42 × f / x

[0168] (In the above formula, a: the titration amount of 0.1N hydrochloric acid methanol solution when only 10 ml of 0.1N dibutylamine toluene solution is titrated, b: the titration amount of 0.1N hydrochloric acid methanol solution when the solution in which the urethane prepolymer is dissolved is titrated, f: the coefficient of 0.1N hydrochloric acid methanol solution, x: the amount of urethane prepolymer.)

[0169] Furthermore, the polyurethane resins used in Examples and Comparative Examples were synthesized by the following method.

[0170] (Synthesis example 1)

[0171] Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer and a nitrogen inlet tube, 71.7 parts by mass of polycarbonate diol (manufactured by Asahi Kasei Chemicals Corporation, trade name "Duranol T5652", average molecular weight 2,000), 0.4 parts by mass of trimethylolpropane, 3.1 parts by mass of dimethylolpropionic acid and 32.9 parts by mass of methyl ethyl ketone were added and mixed uniformly, and then 23.5 parts by mass of dicyclohexylmethane diisocyanate and 0.03 parts by mass of bismuth tris(2-ethylhexanoate) were added, and the mixture was reacted at 80° C. for 240 minutes to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 2.28% relative to the non-volatile component.

[0172] After adding 2.2 parts by mass of triethylamine to the solution and uniformly mixing, 185 parts by mass of water was slowly added to emulsify and disperse the solution, and after adding 2.2 parts by mass of a 30% aqueous solution of hydrazine hydrate and 1.8 parts by mass of a 20% aqueous solution of diethylenetriamine to the obtained emulsified dispersion, the mixture was stirred for 90 minutes to obtain a polyurethane dispersion. Next, the polyurethane dispersion was desolventized at 40°C under reduced pressure to obtain a stable polyurethane aqueous dispersion (PUD-1) having a non-volatile content of 35.0% by mass, a viscosity of 50 mPa·s, and an average particle size of 0.1 μm.

[0173] (Synthesis example 2)

[0174] Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer and a nitrogen inlet tube, 61.9 parts by mass of polycarbonate diol (manufactured by Asahi Kasei Chemicals Corporation, trade name "Duranol T5651", average molecular weight 1,000), 0.2 parts by mass of trimethylolpropane, 3.1 parts by mass of dimethylolpropionic acid and 32.9 parts by mass of methyl ethyl ketone were added and mixed uniformly, and then 32.7 parts by mass of dicyclohexylmethane diisocyanate and 0.03 parts by mass of bismuth tris(2-ethylhexanoate) were added, and the mixture was reacted at 80° C. for 240 minutes to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 3.21% relative to the non-volatile component.

[0175] After adding 2.2 parts by mass of triethylamine to the solution and uniformly mixing, 185 parts by mass of water was slowly added to emulsify and disperse the solution, and 3.0 parts by mass of a 30% aqueous solution of hydrazine hydrate and 2.5 parts by mass of a 20% aqueous solution of diethylenetriamine were added to the obtained emulsified dispersion, followed by stirring for 90 minutes to obtain a polyurethane dispersion. Next, the polyurethane dispersion was desolventized at 40°C under reduced pressure to obtain a stable polyurethane aqueous dispersion (PUD-2) having a non-volatile content of 35.0% by mass, a viscosity of 20 mPa·s, and an average particle size of 0.1 μm.

[0176] (Synthesis example 3)

[0177] Into a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer and a nitrogen inlet tube, 71.7 parts by mass of polycarbonate diol (manufactured by Kuraray Co., Ltd., trade name "KURARAY POLYOL C-2090", average molecular weight 2,000), 0.4 parts by mass of trimethylolpropane, 3.1 parts by mass of dimethylolpropionic acid and 32.9 parts by mass of methyl ethyl ketone were added, and after these were uniformly mixed, 23.5 parts by mass of dicyclohexylmethane diisocyanate and 0.03 parts by mass of bismuth tris(2-ethylhexanoate) were added, and the mixture was reacted at 80° C. for 240 minutes to obtain a methyl ethyl ketone solution of a urethane prepolymer having a free isocyanate group content of 2.28% relative to the non-volatile component.

[0178] After adding 2.2 parts by mass of triethylamine to the solution and uniformly mixing, 185 parts by mass of water was slowly added to emulsify and disperse it, and after adding 2.2 parts by mass of a 30% aqueous solution of hydrazine hydrate and 1.8 parts by mass of a 20% aqueous solution of diethylenetriamine to the obtained emulsified dispersion, the mixture was stirred for 90 minutes to obtain a polyurethane dispersion. Next, the polyurethane dispersion was desolventized at 40°C under reduced pressure to obtain a stable polyurethane aqueous dispersion (PUD-3) having a non-volatile content of 40.0% by mass, a viscosity of 40 mPa·s, and an average particle size of 0.1 μm.

[0179] (Synthesis Example 4)

[0180] 350 parts by mass of polycarbonate diol (manufactured by Asahi Kasei Chemicals Corporation, trade name "Duranol T5652", average molecular weight 2,000) was added to a four-necked flask equipped with a stirrer, a reflux cooling tube, a thermometer, and a nitrogen inlet tube, and dehydrated at a reduced pressure of 0.095 MPa and a temperature of 120 to 130°C. After dehydration, 650 parts by mass of N,N-dimethylformamide and 11 parts by mass of ethylene glycol were added, and the mixture was fully mixed while being cooled to 30°C. Then, 21 parts by mass of hexamethylene diisocyanate and 54 parts by mass of 4,4'-diphenylmethane diisocyanate were added, and mixed at 80°C for 2 hours, and then 0.2 parts by mass of bismuth tris(2-ethylhexanoate) was added, and mixed at 100°C for 8 hours. Next, 360 parts by mass of methyl ethyl ketone was added and mixed while cooling to 70°C, thereby obtaining a polyurethane resin composition (PU-1) having a nonvolatile content of 30.0% by mass.

[0181] (Example 1)

[0182] As shown in Table 1, 10 parts by mass of the aqueous dispersion of the polyurethane obtained in Synthesis Example 1 (PUD-1) as the resin (A), 5 parts by mass of polyglycerol (“POLYGLYCERIN #310” manufactured by Sakamoto Yakuhin Kogyo Co., Ltd., degree of polymerization: 4, molecular weight: 314, OH group value: 1072, number of OH groups: 6) as the compound (B), 9 parts by mass of an associative tackifier (“SN Thickener 612” manufactured by San Nopco Co., Ltd.), and 3 parts by mass of a water-dispersible carbodiimide crosslinking agent (“Carbodilite SV-02” manufactured by Nisshinbo Chemical Co., Ltd.) as the solid content were uniformly mixed using a dispersing device to obtain a surface treatment agent.

[0183] (Examples 2 to 4)

[0184] A surface treatment agent was prepared in the same manner as in Example 1, except that as shown in Table 1, as the (A) resin, 10 parts by mass of the aqueous dispersion of the polyurethane obtained in Synthesis Example 2 (PUD-2), the aqueous dispersion of the polyurethane obtained in Synthesis Example 3 (PUD-3), or the polyurethane resin composition (PU-1) obtained in Synthesis Example 4 were used in place of the aqueous dispersion of the polyurethane obtained in Synthesis Example 1 (PUD-1) in terms of solid content.

[0185] (Example 5)

[0186] A surface treatment agent was prepared in the same manner as in Example 1 except that, as shown in Table 1, an acrylic resin emulsion (“CYBINOL EC-065” manufactured by SAIDEN CHEMICAL INDUSTRY CO., LTD.) was used as 10 parts by mass in terms of solid content instead of the aqueous dispersion of polyurethane (PUD-1) obtained in Synthesis Example 1.

[0187] (Example 6)

[0188] A surface treatment agent was prepared in the same manner as in Example 1 except that 30 parts by mass of an emulsion of polydimethylsilicone (“KM-862T” manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a smoothing agent in terms of solid content to the formulation of Example 1 as shown in Table 1.

[0189] (Example 7)

[0190] A surface treatment agent was prepared in the same manner as in Example 1 except that 20 parts by mass of an acrylic resin emulsion (“CYBINOL EC-065” manufactured by SAIDEN CHEMICAL INDUSTRY CO., LTD.) was added as the resin (A) in terms of solid content to the formulation of Example 1 as shown in Table 1.

[0191] (Example 8)

[0192] A surface treatment agent was prepared in the same manner as in Example 7 except that 30 parts by mass of an emulsion of polydimethylsilicone (“KM-862T” manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a smoothing agent in terms of solid content to the formulation of Example 7 as shown in Table 1.

[0193] (Example 9)

[0194] A surface treatment agent was prepared in the same manner as in Example 8 except that 8 parts by mass of dry-process silica particles (ACEMATT TS100 manufactured by Evonik Degussa Corporation, average particle size: 10 μm) were added as a matting agent to the composition of Example 8 as shown in Table 1.

[0195] (Example 10)

[0196] A surface treatment agent was prepared in the same manner as in Example 9 except that 8 parts by mass of a fluorine-based water and oil repellent (“NK Guard S-740” manufactured by Nikka Chemical Co., Ltd.) as a fluorine-containing compound and 5 parts by mass of a polyester resin emulsion (“NICEPOLE PR-99” manufactured by Nikka Chemical Co., Ltd.) as a hydrophilic compound were added to the formulation of Example 9 as shown in Table 1.

[0197] (Examples 11-12)

[0198] A surface treatment agent was prepared in the same manner as in Example 10 except that the amount of polyglycerol ("POLYGLYCERIN #310" manufactured by Sakamoto Yakuin Kogyo Co., Ltd.) was changed to the amount shown in Table 1.

[0199] (Example 13)

[0200] A surface treating agent was prepared in the same manner as in Example 10 except that 2 parts by mass of triethylenediamine was added as a reaction catalyst in terms of solid content to the blending composition of Example 10 as shown in Table 1.

[0201] (Examples 14 to 24)

[0202] In addition to the compounds shown in Table 1, as the (B) compound, polyglycerol (“POLYGLYCERIN #510” manufactured by Sakamoto Yakuin Kogyo Co., Ltd., degree of polymerization: 6, molecular weight: 462, OH group value: 972, number of OH groups: 8), polyglycerol (“POLYGLYCERIN #750” manufactured by Sakamoto Yakuin Kogyo Co., Ltd., degree of polymerization: 10, molecular weight: 758, OH group value: 888, number of OH groups: 12), triglycerol (number of OH groups: 5), diglycerol (number of OH groups: 4), glycerol (number of OH groups: 3), propylene glycol (number of OH groups: 2), polyvinyl alcohol (“KURARAY POVAL PVA-105” manufactured by Kuraray Co., Ltd., degree of polymerization: 500, degree of saponification: 98.0 to 99.0%), polyvinyl alcohol (“KURARAY POVAL A surface treatment agent was prepared in the same manner as in Example 10, except that 5 parts by mass each of polyvinyl alcohol (“POLYGLYCERIN #310” manufactured by Sakamoto Yakuin Kogyo Co., Ltd.) (“POVAL PVA-117”, degree of polymerization: 1,700, degree of saponification: 98.0 to 99.0%), polyvinyl alcohol (“POVAL PVA-124” manufactured by Kuraray Co., Ltd., degree of polymerization: 2,400, degree of saponification: 98.0 to 99.0%), polyvinyl alcohol (“POVAL PVA-217” manufactured by Kuraray Co., Ltd., degree of polymerization: 1,700, degree of saponification: 87.0 to 89.0%), or a polyimide compound (“Epomin SP-200” manufactured by Nippon Shokubai Co., Ltd., molecular weight 10,000) was used instead of polyglycerol (“POLYGLYCERIN #310” manufactured by Sakamoto Yakuin Kogyo Co., Ltd.).

[0203] (Comparative Example 1)

[0204] A surface treating agent was prepared in the same manner as in Example 10 except that the (B) compound was not blended as shown in Table 1.

[0205] (Comparative Examples 2 to 4)

[0206] A surface treatment agent was prepared in the same manner as in Example 10, except that 5 parts by mass of 2-propanol (number of OH groups: 1), n-propanol (number of OH groups: 1) or hexylamine (number of NH groups: 1) was used as the (B) compound instead of polyglycerol ("POLYGLYCERIN #310" manufactured by Sakamoto Yakuin Kogyo Co., Ltd.).

[0207] <Preparation of leather substrate>

[0208] A skinning agent containing 100 parts by mass of a polyurethane resin (Evafanol HA-68 manufactured by Nikka Chemical Co., Ltd., nonvolatile content 35% by mass), 5 parts by mass of a pigment (SBWhite 11339W manufactured by Mikoku Pigments Co., Ltd., nonvolatile content 67.2% by mass), 1 part by mass of a water-dispersible carbodiimide crosslinking agent (NK Assist CI-02 manufactured by Nikka Chemical Co., Ltd., nonvolatile content 40% by mass), and 3 parts by mass of an associative tackifier (Neo Sticker S manufactured by Nikka Chemical Co., Ltd.) was applied on a release paper (Asahi Release AR-148 manufactured by Asahiroll Co., Ltd.) to a coating thickness of 100 μm (wet coating amount). The film was pre-dried at 80° C. for 2 minutes using a dryer, and then dried at 120° C. for 3 minutes to completely evaporate the water, thereby obtaining a polyurethane resin film (hereinafter also referred to as a “skin layer”).

[0209] A polyurethane adhesive formulation containing 100 parts by mass of a two-component polyurethane resin (Evafanol HO-38 manufactured by Nikka Chemical Co., Ltd., adhesive main agent, non-volatile component 35% by mass), 7 parts by mass of a polyisocyanate curing agent (NK Assist NY-27 manufactured by Nikka Chemical Co., Ltd., non-volatile component 100% by mass), and 5 parts by mass of an associative tackifier (Neo Sticker N manufactured by Nikka Chemical Co., Ltd., non-volatile component 30% by mass) is applied on the surface layer to a coating thickness of 200 μm (wet coating amount).

[0210] Next, the film was dried at 90°C for 1 minute using a dryer, and a polyester knitted fabric as a fiber substrate was immediately laminated thereon. Then, the film was cured at 120°C for 3 minutes, and then aged at 40°C for 72 hours. After the release paper was peeled off, a leather substrate (fiber laminate) for evaluation was obtained.

[0211] <Preparation of leather>

[0212] The surface treatment agent obtained in the examples and comparative examples was applied to the surface layer of the leather substrate obtained above using a 100-mesh gravure coater to a coating amount of 10 to 20 g / m 2 The leather was dried with hot air at 125°C for 3 minutes to prepare a leather for evaluation having a surface treatment layer. The gasochromic property of the leather was evaluated by the following method. The results are shown in Tables 1 and 2.

[0213] (Gaschromicity)

[0214] The gas-induced discoloration properties of the leathers obtained above (Examples 1 to 24 and Comparative Examples 1 to 4) were measured using a nitrogen oxide tester and a nitrogen oxide generator specified in JIS L0855 (1992).

[0215] Specifically, first, the leather obtained above was cut into test pieces of 7 cm in length and 4 cm in width, and the short sides of each test piece were mounted on a radial test stand (capacity: about 15 L) with a clip, and the sample stand was fixed to the frame in the test container of the nitrogen oxide test device. It should be noted that the number of test pieces accommodated at one time was set to 12.

[0216] Next, 50 ml of nitrogen oxides were extracted from the nitrogen oxide storage tank of the nitrogen oxide generator with a syringe and injected from the injection port of the test container. After injection, the paddle in the test container was immediately rotated at a speed of about 270 rpm to make the concentration of nitrogen oxides in the test container uniform. After 60 minutes from the injection of nitrogen oxides, the rotation of the paddle was stopped, the lid of the test device was opened, and each test piece was taken out into the atmosphere. After each test piece was air-dried, the degree of discoloration caused by exposure to nitrogen oxides was measured with a colorimeter as the degree of yellowing, which was graded and evaluated based on 9 levels from 5 to 1 using a gray scale for contaminated colors in accordance with JIS L0805 (2005). It should be noted that in this graded evaluation, the larger the numerical value of the grade, the less discoloration.

[0217] [Table 1]

[0218]

[0219] [Table 2]

[0220]

[0221] By comparing Examples 1 to 24 shown in Tables 1 and 2 with Comparative Example 1, it can be clearly confirmed that when a surface treatment agent in which (B) a compound having two or more active hydrogen atoms is blended in (A) a resin capable of forming a resin layer on the surface of a leather substrate to form a surface treatment layer composed of the surface treatment agent is used (Examples 1 to 24), compared with a case in which a surface treatment agent not containing (B) a compound having two or more active hydrogen atoms in one molecule is used (Comparative Example 1), NO x The leather surface is less discolored by gases and can inhibit NO xYellowing of the leather surface caused by gas. In addition, it can be seen that when a compound having three or more hydroxyl groups in one molecule is added as the (B) compound (Examples 1 to 18 and 20 to 23), the yellowing of the leather surface can be further suppressed compared with the case of adding propylene glycol (Example 19) or polyimide (Example 24). In addition, it can be seen that when a polyglycerol having five or more hydroxyl groups in one molecule is added as the (B) compound (Examples 1 to 16), the yellowing of the leather surface can be further suppressed compared with the case of adding diglycerol (Example 17), glycerol (Example 18) or polyvinyl alcohol (Examples 20 to 23). It can be seen that when a polyglycerol having six or more hydroxyl groups in one molecule is added as the (B) compound (Examples 1 to 10 and 12 to 15), the yellowing of the leather surface can be particularly suppressed compared with the case of adding triglycerol (Example 16).

[0222] On the other hand, when comparing Comparative Examples 2 to 4 shown in Table 2 with Comparative Example 1, it can be seen that when using a surface treatment agent containing a compound having one active hydrogen in one molecule (Comparative Examples 2 to 4), the obtained leather surface exhibits yellowing to the same extent as when using a surface treatment agent not containing (B) a compound having two or more active hydrogen in one molecule (Comparative Example 1). That is, it can be seen that even if a compound having one active hydrogen in one molecule is contained to form a surface treatment layer, it is difficult to suppress the yellowing of the leather surface.

[0223] The above results confirmed that in order to inhibit NO x In order to prevent yellowing of the surface of a leather substrate caused by the above-mentioned reaction, it is effective to form a surface treatment layer on the surface of the leather substrate by adding (B) a compound having two or more active hydrogen atoms in one molecule (preferably a compound having three or more hydroxyl groups in one molecule, more preferably a polyglycerol having five or more hydroxyl groups in one molecule, and further preferably a polyglycerol having six or more hydroxyl groups in one molecule) to (A) a resin capable of forming a resin layer on the surface of the leather substrate.

[0224] Therefore, it was confirmed that the leather surface treatment agent of the present invention can suppress NO contained in the gas generated from the soft polyurethane foam during combustion such as flame in a cushioning composite material obtained by laminating the soft polyurethane foam and various leathers by flame lamination. x The leather surface is not easily yellowed by gas. Even when the leather of the present invention and the flexible polyurethane foam are laminated by flame lamination, the surface is not easily yellowed by burning by flame or the like.

[0225] Industrial Applicability

[0226] As described above, according to the present invention, yellowing of the leather surface can be suppressed. Therefore, since the surface of the leather product using the leather of the present invention is not easy to yellow, it can be used as a stable and high-end leather product and can be applied to various industrial fields such as vehicles, furniture, clothing, bags, shoes, bags, groceries, etc. In particular, the cushioning composite material formed by laminating the leather and the soft polyurethane foam of the present invention by the flame lamination method suppresses the NO contained in the gas generated from the soft polyurethane foam during the flame lamination method. x The yellowing of the leather surface caused by the gas can be used as leather products with excellent surface quality.

Claims

1. A surface treatment agent for leather, wherein: The present invention contains: (A) a resin capable of forming a resin layer on the surface of a leather substrate; and (B) a compound having two or more active hydrogen atoms in one molecule.

2. The leather surface treatment agent according to claim 1, wherein The (B) compound having two or more active hydrogen atoms in one molecule is a compound having three or more hydroxyl groups in one molecule.

3. The leather surface treatment agent according to claim 1, wherein The (B) compound having two or more active hydrogen atoms in one molecule is a glycerol compound.

4. The leather surface treatment agent according to claim 1, wherein The resin (A) capable of forming a resin layer on the surface of the leather substrate is at least one selected from polyurethane resins and acrylic resins.

5. A leather, wherein: The method comprises a leather substrate and a surface-treated layer formed on a surface of the leather substrate using the leather surface-treating agent according to any one of claims 1 to 4.

6. A cushioning composite material, wherein: A leather according to claim 5 comprising a soft polyurethane foam and the leather bonded to a surface of the soft polyurethane foam.

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