Coating composition for leather

Abstract

To provide a leather coating composition that can form, on the surface of leather, a coating layer having excellent water resistance, stain removability and stain resistance.SOLUTION: A leather coating composition contains a particle containing a first polymer having a first repeat unit derived from an unsaturated carboxylate having an alkyl group with 4 or more carbon atoms or a cycloalkyl group with 4 or more carbon atoms, and a liquid medium, with the content of the first repeat unit being 10 mass% or more relative to all the repeat units constituting the first polymer.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a coating composition for leather. [Background technology]

[0002] Leathers such as natural leathers and synthetic leathers are widely used for, for example, the interiors of automobiles, furniture such as sofas, clothing such as coats, etc. It is known that when stains such as denim stains or ballpoint pen stains adhere to the surface of leather, it is difficult to remove the stains.

[0003] For this reason, a coating is applied to the surface of leather to make it easier to remove the above stains (JP Patent Publication 2007-191820). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2007-191820 A Summary of the Invention [Problem to be solved by the invention]

[0005] Coatings applied to the surface of leather are required to have not only the ability to easily remove dirt (hereinafter also referred to as "dirt removability"), but also the ability to prevent dirt from adhering (hereinafter also referred to as "dirt resistance"). In addition, this coating is also required to be water resistant.

[0006] The present invention has been made based on the above circumstances, and an object of the present invention is to provide a coating composition for leather which is capable of forming a coating film on the surface of leather which has excellent water resistance, stain removability and stain resistance. [Means for solving the problem]

[0007] The invention made to solve the above problem is a coating composition for leather, which contains particles including a first polymer having a first repeating unit derived from an unsaturated carboxylate ester having an aliphatic hydrocarbon group having 4 or more carbon atoms, and a liquid medium, and in which the content of the first repeating unit relative to all repeating units constituting the first polymer is 20 mass% or more. Effect of the Invention

[0008] According to the coating composition for synthetic leather of the present invention, a coating film having excellent water resistance, stain removability and stain resistance can be formed on the surface of leather. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The leather coating composition of the present invention will be described in detail below.

[0010] The coating composition for leather (hereinafter, also simply referred to as "coating composition") contains particles (hereinafter, also referred to as "particles [A]") containing a first polymer having a first repeating unit derived from an unsaturated carboxylate ester having an alkyl group having 4 or more carbon atoms or a cycloalkyl group having 4 or more carbon atoms, and a liquid medium (hereinafter, also referred to as "liquid medium [B]"). The coating composition may contain a crosslinking agent (hereinafter, also referred to as "crosslinking agent [C]"). In addition, the coating composition may contain other components (hereinafter, also referred to as "other components") other than the particles [A], the liquid medium [B], and the crosslinking agent [C], within the range that does not impair the effects of the present invention.

[0011] The coating film formed by the coating composition can form a dense film by emulsion fusion, so that adhesion of dirt can be suppressed. Furthermore, the film formed by the coating composition exhibits hydrophilicity as a coating film, so that the attached dirt can be easily removed. The coating composition contains particles containing a polymer having a repeating unit of a specific structure, so that the fluidity during heating is increased, and thus a coating film with excellent water resistance can be obtained.

[0012] Furthermore, the coating film formed by the coating composition has reduced gloss. Since low gloss is also required for the coating of synthetic leather, the coating composition can form a low gloss coating film that meets this requirement. Generally, a matting agent is blended into leather coating to achieve low gloss, but the addition of the matting agent tends to reduce stain resistance. The coating composition can be used without blending a matting agent or with a reduced amount of matting agent, so that both stain resistance and low gloss can be achieved.

[0013] The coating composition is applied to the surface of leather to form a coating film. The method of application to leather is not particularly limited, and examples thereof include known coating methods using a bar coater, etc. The upper limit of the coating film formed on the surface of leather is, for example, preferably 100 μm, more preferably 80 μm, in terms of dry film thickness. The lower limit of the film thickness is preferably 1 μm, more preferably 2 μm, in terms of dry film thickness.

[0014] The leather is not particularly limited, and may be natural leather or synthetic leather. In this specification, "synthetic leather" means leather other than natural leather. The material of the synthetic leather is not particularly limited, and examples thereof include polyurethane and polyvinyl chloride. Examples of synthetic leather include synthetic leather used for automobile interiors, furniture such as sofas, and clothing such as coats.

[0015] Each component contained in the coating composition will be described below.

[0016] <[A] particle> The particles [A] contain a first polymer (hereinafter also referred to as "polymer (Pa)") having a first repeating unit derived from an unsaturated carboxylate ester having an alkyl group having 4 or more carbon atoms or a cycloalkyl group having 4 or more carbon atoms. The particles [A] are usually latex-like particles dispersed in the liquid medium [B] using the liquid medium [B] as a dispersion medium.

[0017] The [A] particles may contain a second polymer (hereinafter also referred to as "polymer (Pb)") having a repeating unit derived from a fluorine-containing ethylene monomer. The [A] particles may contain other polymers than the polymer (Pa) and the polymer (Pb), but it is preferable that the [A] particles do not contain other polymers. The [A] particles may contain components other than the polymers.

[0018] The coating composition can contain one or more types of particles [A].

[0019] [Polymer(Pa)] The polymer (Pa) has a repeating unit (hereinafter also referred to as "repeating unit (Ia)") derived from an unsaturated carboxylic acid ester having an alkyl group having 4 or more carbon atoms or a cycloalkyl group having 4 or more carbon atoms. The polymer (Pa) preferably has a repeating unit (hereinafter also referred to as "repeating unit (Ib)") derived from an unsaturated carboxylic acid ester having an alkyl group having 3 or less carbon atoms. The polymer (Pa) preferably has a repeating unit (hereinafter also referred to as "repeating unit (Ic)") derived from an unsaturated carboxylic acid. The polymer (Pa) may have other repeating units besides the repeating units (Ia), (Ib) and (Ic). The particles [A] may contain one or more types of polymers (Pa).

[0020] (Repeating unit (Ia)) The repeating unit (Ia) is a repeating unit derived from an unsaturated carboxylic acid ester having an alkyl group having 4 or more carbon atoms or a cycloalkyl group having 4 or more carbon atoms. The polymer (Pa) can have one type or two or more types of repeating units (Ia).

[0021] Examples of the alkyl group having 4 or more carbon atoms include linear alkyl groups such as n-butyl group, n-pentyl group, and lauryl group (dodecyl group), and branched alkyl groups such as 2-ethylhexyl group.

[0022] An example of a cycloalkyl group having 4 or more carbon atoms is a cyclohexyl group.

[0023] The lower limit of the number of carbon atoms in the alkyl group or cycloalkyl group is 4. The upper limit of the number of carbon atoms is preferably 20, and more preferably 15. In this specification, the term "number of carbon atoms" refers to the number of carbon atoms constituting the group.

[0024] The unsaturated carboxylic acid constituting the unsaturated carboxylate ester is preferably an ethylenically unsaturated carboxylic acid, for example, an ethylenically unsaturated monocarboxylic acid such as acrylic acid, methacrylic acid, crotonic acid, etc., or an ethylenically unsaturated dicarboxylic acid such as maleic acid, fumaric acid, itaconic acid, etc. Among these, an ethylenically unsaturated monocarboxylic acid is preferred, and acrylic acid or methacrylic acid is more preferred.

[0025] As the unsaturated carboxylate having an alkyl group having 4 or more carbon atoms, butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, or lauryl (meth)acrylate is preferred, and as the unsaturated carboxylate having a cycloalkyl group having 4 or more carbon atoms, cyclohexyl (meth)acrylate is preferred. In this specification, "(meth)acrylic acid" includes both "acrylic acid" and "methacrylic acid".

[0026] The repeating unit (Ia) is preferably a repeating unit derived from an unsaturated carboxylic acid ester having an alkyl group having 4 or more carbon atoms. In this case, the gloss of the coating film formed from the coating composition can be further reduced.

[0027] The lower limit of the content of the repeating unit (Ia) in the polymer (Pa) is 10% by mass, more preferably 20% by mass, and even more preferably 30% by mass, based on the total repeating units constituting the polymer (Pa). The upper limit of the content is preferably 90% by mass, and more preferably 70% by mass. By having the content of the repeating unit (Ia) in the polymer (Pa) within the above range, a coating film having excellent water resistance, stain resistance, and stain removability can be formed.

[0028] (Repeating unit (Ib)) The repeating unit (Ib) is a repeating unit derived from an unsaturated carboxylic acid ester having an alkyl group having 3 or less carbon atoms. When the polymer (Pa) has the repeating unit (Ib), the hydrophilicity of the coating film is improved, and the dirt removability can be further improved. The polymer (Pa) can have one or more types of repeating units (Ib).

[0029] Examples of the unsaturated carboxylate having an alkyl group having 3 or less carbon atoms include methyl (meth)acrylate and ethyl (meth)acrylate.

[0030] The lower limit of the content of the repeating unit (Ib) in the polymer (Pa) is preferably 10% by mass, more preferably 20% by mass, and even more preferably 30% by mass, based on the total repeating units constituting the polymer (Pa). The upper limit of the content is preferably 80% by mass, and more preferably 75% by mass. When the content of the repeating unit (Ib) in the polymer (Pa) is equal to or greater than the lower limit, the hydrophilicity of the coating film is improved, and when the content is equal to or less than the upper limit, the water resistance can be further improved.

[0031] (Repeating unit (Ic)) The repeating unit (Ic) is a repeating unit derived from an unsaturated carboxylic acid. The polymer (Pa) has the repeating unit (Ic), so that particles having excellent dispersion stability can be obtained. The polymer (Pa) can have one or more kinds of repeating units (Ic).

[0032] The unsaturated carboxylic acid is preferably an ethylenically unsaturated carboxylic acid, for example, an ethylenically unsaturated monocarboxylic acid such as acrylic acid, methacrylic acid, crotonic acid, etc., or an ethylenically unsaturated dicarboxylic acid such as maleic acid, fumaric acid, itaconic acid, etc. Among these, an ethylenically unsaturated monocarboxylic acid is preferred, and acrylic acid or methacrylic acid is more preferred.

[0033] The lower limit of the content of the repeating unit (Ic) in the polymer (Pa) is preferably 0.1% by mass, more preferably 0.5% by mass, and even more preferably 1% by mass, based on the total repeating units constituting the polymer (Pa). The upper limit of the content is preferably 15% by mass, and more preferably 10% by mass. When the content of the repeating unit (Ic) in the polymer (Pa) is equal to or greater than the lower limit, the dispersion stability of the particles is further improved, and when the content is equal to or less than the upper limit, the water resistance is further improved.

[0034] (Other repeating units) The other repeating units are repeating units other than the repeating units (Ia), (Ib) and (Ic) described above. Examples of the other repeating units include hydroxyalkyl esters of unsaturated carboxylic acids, alkylene glycol esters of unsaturated carboxylic acids, amino group-containing esters of unsaturated carboxylic acids, polymerizable group-containing alkoxysilanes, and repeating units derived from monomers described in WO 2014 / 112252. The polymer (Pa) may have one or more other repeating units.

[0035] Examples of hydroxyalkyl esters of unsaturated carboxylic acids include hydroxyalkyl esters of (meth)acrylic acid such as 2-hydroxyethyl (meth)acrylate and 3-hydroxypropyl (meth)acrylate.

[0036] Examples of alkylene glycol esters of unsaturated carboxylic acids include polyalkylene glycol esters of (meth)acrylic acid such as polyethylene glycol (meth)acrylate, and alkylene glycol di(meth)acrylates such as ethylene glycol di(meth)acrylate.

[0037] Examples of the amino group-containing ester of an unsaturated carboxylic acid include amino group-containing esters of (meth)acrylic acid such as 1,2,2,6,6-pentamethyl-4-piperidyl (meth)acrylate and dimethylaminoethyl (meth)acrylate.

[0038] Examples of the polymerizable group-containing alkoxysilane include compounds represented by the following formula (b). R 3 n Si(OR 4 ) 4-n (b)

[0039] In the above formula (b), R 3 is a monovalent organic group having 1 to 8 carbon atoms. 3 At least one of R has a polymerizable group. 4 is a monovalent organic group having 1 to 8 carbon atoms. n is an integer of 0 to 3. R 3 If there are multiple, multiple R 3 are the same or different. R 4 If there are multiple, multiple R 4 are the same or different.

[0040] The compound represented by the above formula (b) forms a repeating unit represented by the following formula (c) in the polymer (Pa). R 5 m SiO (4-m) / 2 (c)

[0041] In the above formula (c), R 5 is a monovalent organic group having 1 to 8 carbon atoms. 5 At least one of R is a group derived from a group having a polymerizable group. m is a number from 0 to 3.5 If there are multiple, multiple R 5 are the same or different.

[0042] In the above formulas (b) and (c), R 3 and R 5 Examples of the polymerizable group in R include a vinyl group, a 1-propenyl group, and a (meth)acryloyl group. Among these, a (meth)acryloyl group is preferred. 3 Examples of the monovalent organic group having a polymerizable group represented by the formula (I) include a γ-(meth)acryloxypropyl group. 3 and R 5 The monovalent organic group of R is preferably an alkyl group having 1 to 8 carbon atoms, more preferably a methyl group or an ethyl group. 4 Examples of the monovalent organic group represented by the formula (1) include an alkyl group, an aryl group, and an acyl group having 1 to 8 carbon atoms. Examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, a sec-butyl group, a t-butyl group, and an n-pentyl group. Examples of the aryl group include a phenyl group, a methylphenyl group, an ethylphenyl group, a chlorophenyl group, a bromophenyl group, and a fluorophenyl group. Examples of the acyl group include an acyl group having 1 to 6 carbon atoms, such as an acetyl group, a propionyl group, a butyryl group, a valeryl group, and a caproyl group.

[0043] Examples of the monomers described in WO 2014 / 112252 include carbonyl group-containing compounds, alkoxysilanes, α,β-unsaturated nitriles, conjugated dienes, aromatic vinyl compounds, vinyl ethers, and allyl ethers.

[0044] Examples of carbonyl group-containing compounds include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, diacetone(meth)acrylamide, N,N-dimethylaminopropyl(meth)acrylamide, N-hydroxyethyl(meth)acrylamide, acryloylmorpholine, and acrolein.

[0045] An example of the alkoxysilane is methyltriethoxysilane.

[0046] Examples of the α,β-unsaturated nitrile include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethylacrylonitrile, vinylidene cyanide, and the like.

[0047] Examples of conjugated dienes include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, and 2-chloro-1,3-butadiene.

[0048] Examples of aromatic vinyl compounds include styrene, α-methylstyrene, p-methylstyrene, vinyltoluene, chlorostyrene, divinylbenzene, p-hydroxystyrene, and sodium styrene-4-sulfonate.

[0049] Examples of vinyl ethers include ethyl vinyl ether, propyl vinyl ether, butyl vinyl ether, cyclohexyl vinyl ether, 2-hydroxyethyl vinyl ether, 3-hydroxypropyl vinyl ether, 4-hydroxybutyl vinyl ether, and 2-aminoethyl vinyl ether.

[0050] Examples of allyl ethers include methyl allyl ether, ethyl allyl ether, propyl allyl ether, butyl allyl ether, hydroxyethyl allyl ether, hydroxypropyl allyl ether, hydroxybutyl allyl ether, allyl glycidyl ether, ethylene glycol monoallyl ether, and propylene glycol monoallyl ether.

[0051] When the polymer (Pa) has other repeating units, the lower limit of the content of the other repeating units in the polymer (Pa) is preferably 0.1% by mass, more preferably 1% by mass, based on the total repeating units constituting the polymer (Pa).The upper limit of the content is preferably 30% by mass, more preferably 15% by mass.

[0052] [Polymer (Pb)] The polymer (Pb) has a repeating unit derived from a fluorine-containing ethylene monomer (hereinafter also referred to as "repeating unit (IIa)"). The polymer (Pb) may have a repeating unit other than the repeating unit (IIa). When the [A] particles further contain a polymer (Pb), the stain resistance and stain removability can be further improved. When the [A] particles contain a polymer (Pb), the [A] particles can contain one or more types of polymers (Pb).

[0053] (Repeating unit (IIa)) The repeating unit (IIa) is a repeating unit derived from a fluorine-containing ethylene monomer. The polymer (Pb) may have one or more kinds of repeating units (IIa).

[0054] The fluorine-containing ethylene monomer is a compound having an ethylenic carbon-carbon double bond and a fluorine atom. Examples of the fluorine-containing ethylene monomer include fluorinated olefins, fluorinated olefin chlorides, (meth)acrylates having fluorine atoms, and perfluoroalkyl vinyl ethers. Examples of the fluorinated olefins include vinylidene fluoride, tetrafluoroethylene, and hexafluoropropylene, examples of the fluorinated olefins include trifluorochloroethylene, examples of the (meth)acrylates having fluorine atoms include the compound represented by the following formula (a), (meth)acrylic acid 3-[4[1-trifluoromethyl-2,2-bis[bis(trifluoromethyl)fluoromethyl]ethynyloxy]benzooxy]-2-hydroxypropyl, and examples of the perfluoroalkyl vinyl ethers include trifluoromethyl trifluorovinyl ether and heptafluoropropyl trifluorovinyl ether.

[0055] [ka]

[0056] In the above formula (a), R 1 R is a hydrogen atom or a methyl group. 2 is a monovalent fluorohydrocarbon group having 1 to 18 carbon atoms.

[0057] R in formula (a) 2 Examples of R include a fluorinated alkyl group having 1 to 12 carbon atoms, a fluorinated aryl group having 6 to 16 carbon atoms, and a fluorinated aralkyl group having 7 to 18 carbon atoms. Among these, a fluorinated alkyl group having 1 to 12 carbon atoms is preferred. 2Preferred specific examples of the above include a 2,2,2-trifluoroethyl group, a 2,2,3,3,3-pentafluoropropyl group, a 1,1,1,3,3,3-hexafluoropropan-2-yl group, a β-(perfluorooctyl)ethyl group, a 2,2,3,3-tetrafluoropropyl group, a 2,2,3,4,4,4-hexafluorobutyl group, a 1H,1H,5H-octafluoropentyl group, a 1H,1H,9H-hexadecafluoro-1-nonyl group, a 1H,1H,11H-icosafluoroundecyl group, and a perfluorooctyl group.

[0058] Among these, the fluorine-containing ethylene monomer is preferably a fluorinated olefin, more preferably vinylidene fluoride, tetrafluoroethylene or hexafluoropropylene, still more preferably vinylidene fluoride or hexafluoropropylene, and particularly preferably vinylidene fluoride. When these compounds are used as the fluorine-containing ethylene monomer, the stability of the system during emulsion polymerization is further improved, and the particles [A] can be formed more effectively.

[0059] The lower limit of the content of the repeating unit (IIa) in the polymer (Pb) is preferably 70% by mass, more preferably 80% by mass, based on the total repeating units constituting the polymer (Pb).The upper limit of the content is preferably 100% by mass, more preferably 90% by mass.

[0060] (Repeating units derived from other monomers) As the other monomer, the monomers described in International Publication No. 2014 / 112252 can be used. For example, unsaturated carboxylic acid, α,β-unsaturated nitrile, carbonyl group-containing compound, conjugated diene, aromatic vinyl compound, vinyl ether, allyl ether, polymerizable group-containing alkoxysilane, unsaturated carboxylate ester, etc. can be mentioned. The polymer (Pb) can have one or more other repeating units.

[0061] Examples of the unsaturated carboxylic acid include the same as those exemplified as the unsaturated carboxylic acid in the repeating unit (Ic) of the above-mentioned polymer (Pa).

[0062] Examples of the α,β-unsaturated nitrile include the same α,β-unsaturated nitriles as those exemplified as the α,β-unsaturated nitriles in the other repeating units in the above-mentioned polymer (Pa).

[0063] Examples of the carbonyl group-containing compound include the same compounds as those exemplified as the carbonyl group-containing compound in the other repeating units in the above-mentioned polymer (Pa).

[0064] Examples of the conjugated diene include the same ones as those exemplified as the conjugated dienes in the other repeating units in the above-mentioned polymer (Pa).

[0065] Examples of the aromatic vinyl compound include the same compounds as those exemplified as the aromatic vinyl compounds in the other repeating units in the above-mentioned polymer (Pa).

[0066] Examples of the vinyl ether include the same vinyl ethers as those exemplified as the vinyl ethers in the other repeating units in the above-mentioned polymer (Pa).

[0067] Examples of the allyl ether include the same allyl ethers as those exemplified as the allyl ethers in the other repeating units in the above-mentioned polymer (Pa).

[0068] Examples of the polymerizable group-containing alkoxysilane include the same ones as those exemplified as the polymerizable group-containing alkoxysilane in the above-mentioned polymer (Pa).

[0069] Examples of the unsaturated carboxylic acid ester include alkyl esters of the above-mentioned unsaturated carboxylic acids and hydroxyalkyl esters of the above-mentioned unsaturated carboxylic acids.

[0070] When the polymer (Pb) has other repeating units, the lower limit of the content of the repeating units is preferably 0% by mass, more preferably 10% by mass, based on the total repeating units constituting the polymer (Pb).The upper limit of the content is preferably 30% by mass, more preferably 20% by mass.

[0071] [[A]Particle properties] (Average particle size) The lower limit of the average particle size of the particles [A] is preferably 30 nm, more preferably 50 nm, and even more preferably 80 nm. The upper limit of the average particle size is preferably 6,000 nm. By having the average particle size of the particles [A] within the above range, a dense coating film can be formed when the particles are formed.

[0072] When the average particle diameter of the [A] particles is 500 nm or more (hereinafter also referred to as "large particle diameter"), a coating film with reduced gloss can be formed. The lower limit of the average particle diameter of the large particle diameter [A] particles is 500 nm or more, preferably 550 nm. The upper limit of the average particle diameter is preferably 6,000 nm, more preferably 5000 nm, and even more preferably 4000 nm. By having the average particle diameter of the large particle diameter [A] particles within the above range, a coating film with even reduced gloss can be formed.

[0073] When the particles [A] have a large particle size, it is preferable that the above-mentioned polymer (Pa) further contains a repeating unit derived from a crosslinkable monomer. In this case, a coating film with even lower gloss can be formed. The "crosslinkable monomer" refers to a compound having at least two ethylenically unsaturated groups.

[0074] Examples of the crosslinkable monomer include allyl methacrylate, allyl acrylate, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate, diallyl maleate, divinyl adipate, divinylbenzene, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, triethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, tetramethylolmethane tetramethacrylate, pentaerythritol tri(meth)acrylate, pentaerythritol tetra(meth)acrylate, ditrimethylolpropane tetra(meth)acrylate, dipentaerythritol hexa(meth)acrylate, dipropylene glycol dimethacrylate, divinylbenzene, and acrylates thereof. Among these, allyl methacrylate, triallyl isocyanurate, or ethylene glycol dimethacrylate is preferred, and allyl methacrylate is more preferred. The polymer (Pa) may have a repeating unit derived from one or more crosslinkable monomers.

[0075] The lower limit of the content of the repeating unit derived from the crosslinkable monomer is preferably 0.01% by mass, more preferably 0.1% by mass, based on the total repeating units constituting the polymer (Pa).The upper limit of the content is preferably 10% by mass, more preferably 5% by mass.

[0076] In this specification, the average particle size of the [A] particles is the particle size (D50) value at which the cumulative frequency of the number of particles is 50% when the particle size distribution is measured using a particle size distribution measuring device that uses light scattering as the measurement principle, and the particles are accumulated from the smallest particle. An example of such a particle size distribution measuring device is the "FPAR-1000" manufactured by Otsuka Electronics Co., Ltd. The particle size distribution measuring device can evaluate not only the primary particles of the [A] particles, but also the secondary particles formed by the aggregation of the primary particles. Therefore, the particle size distribution measured by these particle size distribution measuring devices can be used as an index of the dispersion state of the [A] particles contained in the coating composition.

[0077] (Endothermic peak temperature) The particles [A] preferably have at least one endothermic peak in the temperature range of -50°C to +95°C when measured by differential scanning calorimetry (DSC) in accordance with JIS-K7121-2012. The temperature of one of the endothermic peaks possessed by the particles [A] is more preferably in the range of -30°C to +95°C, and even more preferably in the range of -20°C to +95°C. When the temperature of one of the endothermic peaks possessed by the particles [A] is in the above range, the particles [A] can impart better flexibility and adhesion to a coating film.

[0078] In addition, when the particles [A] are measured by differential scanning calorimetry (DSC) in accordance with JIS-K7121-2012, it is preferable that, in addition to the above-mentioned endothermic peak, one or more endothermic peaks are observed in a temperature range of more than 90°C and less than or equal to 150°C.

[0079] (Tetrahydrofuran (THF) insolubles) The THF insoluble content of the [A] particles is preferably 50% by mass or more, more preferably 60% by mass or more. The THF insoluble content is an index of the solvent resistance of the resulting coating film. Therefore, by setting the THF insoluble content within the above range, even when a coating film is formed using the coating composition and then an organic solvent-based coating film is further laminated thereon, it is considered preferable because it can suppress the elution of the polymer into the organic solvent-based coating film. In addition, the THF insoluble content can also be one of the indexes of the durability of the resulting coating film. Therefore, it is considered that the durability is improved by setting the THF insoluble content within the above range.

[0080] [[A] Particle synthesis method] The particles [A] can be produced, for example, by emulsion polymerizing a predetermined monomer according to a known method to form a polymer (Pa). The particles [A] can be synthesized, for example, by a known emulsion polymerization process or an appropriate combination thereof, without any particular limitation, as long as the repeating unit of the polymer (Pa) has the above-mentioned structure, by the method described in WO 2014 / 112252.

[0081] When the particles [A] contain a polymer (Pb), the particles can be synthesized, for example, by forming a polymer (Pb) having a repeating unit derived from a fluorine-containing ethylene monomer by a known method, then adding a monomer for forming the polymer (Pa) to this polymer (Pb), absorbing the monomer into the mesh structure of the particles of the polymer (Pb), and then polymerizing the monomer absorbed in the mesh structure of the polymer (Pb) to form the polymer (Pa).

[0082] When the particles [A] have a large particle size, the particles [A] having a large particle size can be produced, for example, by adding polyvinyl alcohol when a predetermined monomer is emulsion-polymerized according to a known method.

[0083] <[B] Liquid medium> [B] The liquid medium is preferably an aqueous medium containing water. This aqueous medium may contain a non-aqueous medium other than water. In order to improve the coatability of the coating composition, a non-aqueous medium having a normal boiling point of 60°C or more and 350°C or less may be contained. Specific examples of such non-aqueous media include amides such as N-methylpyrrolidone, dimethylformamide, and N,N-dimethylacetamide; hydrocarbons such as toluene, xylene, n-dodecane, and tetralin; alcohols such as methanol, ethanol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, t-butyl alcohol, ethylene glycol, glycerin, propylene glycol, 2-ethyl-1-hexanol, 1-nonanol, and lauryl alcohol; ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, phorone, acetophenone, and isophorone; esters such as ethyl acetate, butyl acetate, benzyl acetate, isopentyl butyrate, methyl lactate, ethyl lactate, and butyl lactate; amines such as o-toluidine, m-toluidine, and p-toluidine; lactones such as γ-butyrolactone and δ-valerolactone; sulfoxides such as dimethyl sulfoxide, and sulfone compounds such as sulfolane.

[0084] When the liquid medium [B] contains water and a non-aqueous medium other than water, the lower limit of the water content in the liquid medium [B] is preferably 80 mass %, more preferably 90 mass %. By using an aqueous medium as the liquid medium [B], the coating composition has a low adverse effect on the environment and is safer for workers who handle it.

[0085] <[C] Crosslinking agent> The coating composition may contain a crosslinking agent [C]. By containing the crosslinking agent [C] in the coating composition, the coating film can be densified by crosslinking, and water resistance can be imparted. It is preferable that the crosslinking agent [C] is dissolved in the liquid medium [B].

[0086] Examples of the crosslinking agent [C] include hydrazine derivatives, carbodiimide compounds, isocyanate compounds, amino compounds, epoxy compounds, alkoxysilyl group-containing compounds, metal crosslinking agents, oxazoline compounds, acid anhydrides, and aziridine compounds.

[0087] The hydrazine derivative may be, for example, a compound having at least two hydrazino groups. The lower limit of the content of the hydrazine derivative is preferably 0.02 mol, more preferably 0.2 mol, per mol of carbonyl group contained in the [A] particle. The upper limit of the content is preferably 1.1 mol, more preferably 1.0 mol. If the content of the hydrazine derivative is less than 0.02 mol, or more than 1.1 mol, per mol of carbonyl group contained in the [A] particle, the water resistance and solvent resistance of the coating film formed may be insufficient.

[0088] Examples of the hydrazine derivative having at least two hydrazino groups include dihydrazide dicarboxylic acid having 2 to 10 carbon atoms, preferably 4 to 6 carbon atoms, such as oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, isophthalic acid dihydrazide, sebacic acid dihydrazide, maleic acid dihydrazide, fumaric acid dihydrazide, and itaconic acid dihydrazide, and water-soluble aliphatic dihydrazine having 2 to 4 carbon atoms, such as ethylene-1,2-dihydrazine, propylene-1,3-dihydrazine, and butylene-1,4-dihydrazine. Among these, adipic acid dihydrazide is preferred. The hydrazine derivative has the effect of forming a coating having a network structure by reacting the carbonyl group of the polymer with the hydrazino group in the hydrazine derivative when the water in the composition is dispersed by drying. This crosslinking reaction usually does not require a catalyst, but if necessary, a water-soluble metal salt such as zinc sulfate, manganese sulfate, cobalt sulfate, or the like can be used as a catalyst.

[0089] Examples of commercially available carbodiimide compounds include "Carbodilite E-02", "Carbodilite E-03A", "Carbodilite E-04", "Carbodilite E-05", "Carbodilite V-02", "Carbodilite SV-02", "Carbodilite V-02-L2", "Carbodilite V-04", and "Carbodilite V-10" manufactured by Nisshinbo Chemical Co., Ltd. Among these, "Carbodilite V-02-L2", "Carbodilite V-02" and "Carbodilite E-05" are preferred.

[0090] Specific examples of the isocyanate compound include 2,4-tolylene diisocyanate, diphenylmethane-4,4'-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine methyl ester diisocyanate, methylcyclohexyl diisocyanate, trimethylhexamethylene diisocyanate, hexamethylene diisocyanate, n-pentane-1,4-diisocyanate, trimers thereof, adducts or biurets thereof, polymers thereof having two or more isocyanate groups, lysine triisocyanate, blocked isocyanates, and the like.

[0091] Specific examples of amino compounds include melamine resins, urea resins, guanamine resins, amine adducts, polyamides, and other amino acid-based substances (for example, "AC454" by Tosoh Corporation).

[0092] Specific examples of the epoxy compound include epoxy resins, epoxy-modified silane coupling agents, and the like.

[0093] Specific examples of alkoxysilyl group-containing compounds include methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, 3-trimethoxysilylpropyl succinic anhydride, 3-isocyanatepropyltriethoxysilane, and tris-(trimethoxysilylpropyl)isocyanurate.

[0094] Specific examples of metal-based crosslinking agents include organic titanium compounds such as titanium lactate, and zirconium compounds such as ammonium zirconium carbonate. Commercially available titanium lactate products include "Orgatics TC-310" from Matsumoto Fine Chemical Co., Ltd. Commercially available ammonium zirconium carbonate products include "AZ Coat 5800MT" from San Nopco Co., Ltd.

[0095] When the coating composition contains the crosslinking agent [C], the lower limit of the content of the crosslinking agent [C] is preferably 0.1 parts by mass, more preferably 1 part by mass, relative to 100 parts by mass of the particles [A].The upper limit of the content is preferably 20 parts by mass, more preferably 10 parts by mass.

[0096] Examples of the method for adding the crosslinking agent [C] include a method in which the crosslinking agent [C] is dissolved or dispersed in water and then added to the composition, a method in which the crosslinking agent [C] is dissolved in a small amount of a water-soluble organic solvent and then added to the composition, and a method in which the crosslinking agent [C] is directly added to the composition.

[0097] <Other optional ingredients> The coating composition may contain other optional components other than the particles [A], the liquid medium [B], and the crosslinking agent [C], as necessary. Examples of the other optional components include matting agents, aqueous urethane resins, fillers, surface preparation agents, weather resistance improvers, thickeners, defoamers, film-forming assistants, antifreeze agents, pH adjusters, wettability improvers, pigments, and the like. These may also be commercially available products. The coating composition may contain one or more other optional components.

[0098] Methods for adding other optional components include, for example, a method in which the other optional components are dissolved or dispersed in water and then added to the composition, a method in which the other optional components are dissolved in a small amount of a water-soluble organic solvent and then added to the composition, a method in which the other optional components are directly added to the composition, and a method in which the other optional components are added to the polymerization system when synthesizing the polymer (Pa) that constitutes the [A] particles.

[0099] [Method of preparing the coating composition] The coating composition can be prepared, for example, by preparing a dispersion of the [B] liquid medium containing the [A] particles, and mixing this dispersion with a suspension of the [C] crosslinker in the [B] liquid medium, other optional components, etc. as necessary. The lower limit of the solid content concentration of the coating composition is preferably 1% by mass, more preferably 10% by mass, and even more preferably 30% by mass. The upper limit of the solid content concentration is preferably 80% by mass, more preferably 70% by mass, and even more preferably 60% by mass. EXAMPLES

[0100] The present invention will be described in detail below based on examples, but the present invention is not limited to these examples in any way.

[0101] <Synthesis of [A] particles> [A] The abbreviations for the components used in the synthesis of particles are shown below. EHA: 2-Ethylhexyl acrylate BA: Butyl acrylate BMA: Butyl methacrylate LA: Lauryl acrylate CHMA: Cyclohexyl methacrylate MMA: Methyl methacrylate EA: Ethyl acrylate DAAM: Diacetone acrylamide AA: Acrylic acid MAA: Methacrylic acid AN: Acrylonitrile HEMA: 2-hydroxyethyl methacrylate AMA: Allyl methacrylate PEGMA: polyethylene glycol methacrylate (NOF Corp.'s "PE-200", average oxyethylene addition mole number: 4.5) PMPMA: 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (ADEKA Corporation's "LA-82") MAPS: 3-(trimethoxysilyl)propyl methacrylate VDF: Vinylidene fluoride TFE: Tetrafluoroethylene HFP: Hexafluoropropylene

[0102] [Synthesis Example 1] Synthesis of particles (S1) In a reaction vessel, 30 parts by mass of 2-ethylhexyl acrylate (EHA), 2 parts by mass of cyclohexyl methacrylate (CHMA), 60 parts by mass of methyl methacrylate (MMA), 5 parts by mass of methacrylic acid (MAA), 1 part by mass of acrylonitrile (AN), 1 part by mass of polyethylene glycol methacrylate (PEGMA), 1 part by mass of 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (PMPMA), 2 parts by mass of an emulsifier (ADEKA Corporation's "ADEKA REASOAP SR10"), 1 part by mass of sodium dodecylbenzenesulfonate, and 100 parts by mass of water were mixed and thoroughly stirred to prepare a monomer emulsion. After 50 parts by mass of water were charged into a separable flask, the temperature was raised in a water bath, and 0.3 parts by mass of ammonium persulfate was added as a polymerization initiator when the internal temperature of the separable flask reached 50°C. When the internal temperature of the separable flask reached 75° C., the addition of the monomer emulsion was started, and the monomer emulsion was slowly added over 2 hours while maintaining the internal temperature of the separable flask at 75° C. Thereafter, the internal temperature of the separable flask was raised to 85° C., and this temperature was maintained for 1 hour to carry out a polymerization reaction, and polymer (Pa-1) was polymerized. Thereafter, the separable flask was cooled to stop the reaction, ammonia water was added to adjust the pH to 7.6, and water was added to adjust the solid content concentration, and an aqueous dispersion containing 35% by mass of particles (S1) was obtained.

[0103] [Synthesis Example 2] Synthesis of particles (S2) A polymer (Pa-2) was synthesized in the same manner as in Synthesis Example 1 except that the types and amounts of monomers shown in Table 1 below were used, and an aqueous dispersion containing 35 mass % of particles (S2) was obtained.

[0104] [Synthesis Example 3] Synthesis of particles (S3) In a reaction vessel, 46.5 parts by mass of 2-ethylhexyl acrylate (EHA), 49.5 parts by mass of methyl methacrylate (MMA), 3 parts by mass of methacrylic acid (MAA), 1 part by mass of allyl methacrylate (AMA), 5 parts by mass of an emulsifier (Kuraray Co., Ltd.'s "Poval 5-88"), and 50 parts by mass of water were mixed and thoroughly stirred to prepare a monomer emulsion. 45 parts by mass of water were charged into a separable flask. After the inside of the separable flask was thoroughly replaced with nitrogen, the temperature was raised in a water bath, and when the internal temperature of the separable flask reached 82°C, 0.03 parts by mass of ammonium persulfate was added as a polymerization initiator. One minute after the addition of the polymerization initiator, the addition of the monomer emulsion was started, and the monomer emulsion was slowly added over 4 hours while maintaining the internal temperature of the separable flask at 82°C. At that time, 0.02 parts of ammonium persulfate was additionally added every hour. Thereafter, the internal temperature of the separable flask was maintained at 82° C. for 3 hours to carry out a polymerization reaction, and a polymer (Pa-3′) was polymerized. Thereafter, the separable flask was cooled to terminate the reaction, and ammonia water was added to adjust the pH to 5.0, and water was added to adjust the solid content concentration, thereby obtaining an aqueous dispersion containing 46 mass % of particles (S3′).

[0105] Next, 46.5 parts by mass of 2-ethylhexyl acrylate (EHA), 49.5 parts by mass of methyl methacrylate (MMA), 3 parts by mass of methacrylic acid (MAA), 1 part by mass of allyl methacrylate (AMA), 5 parts by mass of emulsifier (Kuraray Co., Ltd.'s "Poval 5-88") and 50 parts by mass of water were mixed in a reaction vessel and thoroughly stirred to prepare a monomer emulsion. 11 parts by mass of the aqueous dispersion containing the particles (S3') of the polymer (Pa-3') obtained above (5 parts by mass of polymer (Pa-3')) and 45 parts by mass of water were charged into a separable flask. After thoroughly replacing the inside of the separable flask with nitrogen, the temperature was raised in a water bath, and when the internal temperature of the separable flask reached 82°C, 0.03 parts by mass of ammonium persulfate was added as a polymerization initiator. One minute after the addition of the polymerization initiator, the addition of the monomer emulsion was started, and the monomer emulsion was slowly added over 4 hours while maintaining the internal temperature of the separable flask at 82°C. At that time, 0.02 parts of ammonium persulfate was added every hour. Then, the internal temperature of the separable flask was maintained at 82°C for 3 hours to carry out a polymerization reaction, and polymer (Pa-3) was polymerized. Then, the separable flask was cooled to stop the reaction, ammonia water was added to adjust the pH to 5.0, and water was added to adjust the solid content concentration, and an aqueous dispersion containing 35% by mass of particles (S3) was obtained.

[0106] [Synthesis Example 4] Synthesis of particles (S4) A polymer (Pa-4) was synthesized in the same manner as in Synthesis Example 3 except that the types and amounts of monomers shown in Table 1 below were used, and an aqueous dispersion containing 35 mass % of particles (S4) was obtained.

[0107] [Synthesis Example 5] Synthesis of particles (S5) After thoroughly replacing the inside of an autoclave with a capacity of about 6 L and equipped with an electromagnetic stirrer with nitrogen, 2.5 L of deoxygenated pure water and 25 g of ammonium perfluorodecanoate as an emulsifier were charged and heated to 60°C while stirring at 350 rpm. Next, a mixed gas consisting of 720 parts by mass of vinylidene fluoride (VDF) and 180 parts by mass of hexafluoropropylene (HFP) was added to an autoclave with an internal pressure of 20 kg / cm. 2The polymerization was started by injecting 25 g of a Freon 113 solution containing 20% ​​by mass of diisopropyl peroxydicarbonate as a polymerization initiator using nitrogen gas. During the polymerization, the internal pressure was kept at 20 kg / cm 2 A mixed gas consisting of 720 parts by mass of VDF and 180 parts by mass of HFP was gradually injected to maintain the pressure at 20 kg / cm. 2 The temperature was maintained at 40° C. Also, since the polymerization rate decreased as the polymerization proceeded, after 3 hours had elapsed, the same amount of the same polymerization initiator solution as before was pressurized using nitrogen gas, and the reaction was continued for another 3 hours. Thereafter, the reaction liquid was cooled and stirring was stopped at the same time, and the reaction was terminated after the unreacted monomer was released, thereby obtaining an aqueous dispersion containing 40% by mass of fine particles of polymer (Pb-1). For the obtained polymer (Pb-1), 19 F-NMR analysis revealed that the mass composition ratio of each monomer was VDF / HFP=720 / 180.

[0108] After thoroughly replacing the inside of the separable flask with nitrogen, 2250 parts by mass of the aqueous dispersion containing the fine particles of polymer (Pb-1) obtained in the above process (900 parts by mass of polymer (Pb-1)), 1 part by mass of sodium polyoxyethylene dodecyl ether sulfate, and 100 parts by mass of water were charged. In a separate container, 900 parts by mass of the polymer (Pb-1) contained in this aqueous dispersion was mixed with 49 parts by mass of 2-ethylhexyl acrylate (EHA), 5 parts by mass of cyclohexyl methacrylate (CHMA), 30 parts by mass of methyl methacrylate (MMA), 5 parts by mass of diacetone acrylamide (DAAM), 2 parts by mass of acrylic acid (AA), 2 parts by mass of methacrylic acid (MAA), 5 parts by mass of acrylonitrile (AN), 1 part by mass of 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate (PMPMA), 1 part by mass of 3-(trimethoxysilyl)propyl methacrylate (MAPS), 2 parts by mass of an emulsifier (ADEKA Corporation's "ADEKA REASOAP SR10"), 1 part by mass of 2-ethylhexyl thioglycolate, and 400 parts by mass of water, and thoroughly stirred to prepare a monomer emulsion. Then, the separable flask was heated in a water bath, and when the internal temperature of the separable flask reached 50°C, 0.5 parts by mass of ammonium persulfate was added as a polymerization initiator. When the internal temperature of the separable flask reached 75°C, the addition of the monomer emulsion prepared above was started, and the monomer emulsion was slowly added over 2 hours while maintaining the internal temperature of the separable flask at 75°C. Then, the internal temperature of the separable flask was heated to 85°C, and this temperature was maintained for 1 hour to carry out a polymerization reaction, and a polymer (Pa-5) was polymerized. Then, the separable flask was cooled to stop the reaction, and ammonia water was added to adjust the pH to 7.6, and water was added to adjust the solid concentration, and an aqueous dispersion containing 35% by mass of particles (S5) was obtained.

[0109] [Synthesis Example 6] Synthesis of particles (S6) An aqueous dispersion containing 35 mass % of particles (S6) was obtained in the same manner as in Synthesis Example 5, except that the types and amounts of monomers shown in Table 1 below were used.

[0110] [Synthesis Example 7] Synthesis of particles (S7) Aqueous dispersions containing 35 mass % of particles (S7) were obtained in the same manner as in Synthesis Example 1, except that the types and amounts of monomers shown in Table 1 below were used.

[0111] <[A] Physical properties of particles> The average particle size, THF insoluble matter, and endothermic peak temperature of the synthesized particles [A] were measured by the following methods. The results are shown in Table 1 below.

[0112] [Average particle size] The particle size distribution of the aqueous dispersion was measured using a particle size distribution measuring device (Otsuka Electronics Co., Ltd.'s "FPAR-1000") that uses dynamic light scattering as its measurement principle, and the average particle diameter (D50) was calculated from the particle size distribution.

[0113] [THF insolubles] About 10 g of the obtained aqueous dispersion was weighed into a petri dish made of Teflon (registered trademark) with a diameter of 8 cm, and dried at 120° C. for 1 hour to form a membrane. 1 g of the obtained membrane was immersed in 400 mL of tetrahydrofuran (THF) and shaken at 50° C. for 3 hours. Next, the THF phase was filtered through a 300-mesh wire screen to separate the insoluble matter, and the THF insoluble matter (%) was calculated from the measured value of the mass (Y(g)) of the residue obtained by evaporating and removing the THF solvent from the THF phase, using the following formula. THF insolubles (%) = ((1-Y) / 1) x 100

[0114] [Endothermic peak temperature] The aqueous dispersion was measured by differential scanning calorimetry (DSC) and an endothermic peak was observed.

[0115] In Table 1 below, "-" in the "Polymer (Pa)" and "Polymer (Pb)" columns indicates that the corresponding component was not used.

[0116] [Table 1]

[0117] <Preparation of Coating Composition and Formation of Coating Film> The components other than the particles [A] used in the preparation of the coating composition are shown below.

[0118] [[C] Crosslinking agent] (C-1): Adipic acid dihydrazide from Otsuka Chemical Co., Ltd. (C-2): "Carbodilite E-05" by Nisshinbo Chemical Co., Ltd. (C-3): "KBM9659" by Shin-Etsu Chemical Co., Ltd.

[0119] [Other ingredients] Water-based urethane resin: "Superflex 460" by Daiichi Kogyo Seiyaku Co., Ltd. Matting agent: Evonik's "ACEMATT TS100"

[0120] [Example 1] Preparation of coating composition (T1) and formation of coating film [A] 286 parts by mass of water dispersion containing particles (S1) as particles (containing 100 parts by mass of particles (S1)) was added to 25 parts by mass of water dispersion of (C-2) as crosslinking agent (containing 10 parts by mass of solid content) and stirred at 300 rpm to prepare coating composition (T1). Coating composition (T1) was applied to the surface of urethane synthetic leather using a bar coater so that the dry film thickness was 2 to 20 μm, and the coating was formed by drying at 120° C. for 2 minutes.

[0121] [Examples 2 to 10 and Comparative Examples 1 to 2] Coating compositions (T2) to (T10) and (CT1) to (CT2) were prepared and coating films were formed in the same manner as in Example 1, except that the types and amounts of each component shown in Table 2 below were used.

[0122] <Evaluation> The coating film formed above was evaluated for water resistance, stain resistance, stain removability, and gloss according to the following methods. The results are shown in Table 2 below. In Table 2 below, "-" indicates that the corresponding component was not used.

[0123] [water resistance] The coating was set on the curved surface of a Gakushin-type friction fastness tester (Daiei Kagaku Seiki Seisakusho Co., Ltd. "RT-300") and a friction test was carried out 10 times back and forth using a water-soaked Bemcot and a friction element equipped with a 300g weight. The coating was visually observed before and after the friction test and water resistance was evaluated. Water resistance was rated as "A" (very good) if there was no change in appearance, "B" (good) if there was some loss of gloss, "C" (fairly good) if there was significant loss of gloss, "D" (poor) if the coating had partially peeled off, and "E" (very poor) if no coating remained.

[0124] [Stain resistance] The coating was set on the curved surface of the Gakushin-type friction fastness tester, and a soiled cloth (DENIM 2550Y) and a 500g weight were attached to the friction element to perform a soiled friction test with 100 round trips. The Lab values ​​before and after the soiled friction test were measured with a handy color difference meter (Konica Minolta's "CM-700d"), and the color difference ΔE was calculated. The stain resistance was evaluated as "A" (very good) when ΔE was less than 5, "B" (good) when it was 5 or more and less than 7, "C" (fairly good) when it was 7 or more and less than 9, "D" (poor) when it was 9 or more and less than 11, and "E" (very poor) when it was 11 or more.

[0125] [Stain removal] The coating film after the stain rubbing test in the "stain resistance" test above was wiped by hand with a water-soaked Bemcot, and the end point was the point at which no stain remained on the Bemcot side. The Lab value after wiping with water was measured in the same manner as in the "stain resistance" test above, and the color difference ΔE was calculated using the Lab value before the stain rubbing test. Stain removability was evaluated as "A" (very good) when ΔE was less than 3, "B" (very good) when it was between 3 and 5, "C" (good) when it was between 5 and 7, "D" (poor) when it was between 7 and 9, and "E" (very poor) when it was 9 or more.

[0126] [Glossiness] The 60° gloss of the coating film before the "stain resistance" test was measured using a gloss meter (BYK's "micrо-TRI-glоss"). The lower the 60° gloss value, the lower the gloss. Gloss was evaluated as follows: if the 60° gloss was less than 3, it was rated as "A" (very good); if it was between 3 and 5, it was rated as "B" (very good); if it was between 5 and 7, it was rated as "C" (good); if it was between 7 and 9, it was rated as "D" (poor); and if it was 9 or more, it was rated as "E" (very poor).

[0127] [Table 2]

[0128] The results in Table 2 reveal that the coating film formed by the coating composition of the Example is superior in water resistance, stain resistance and stain removability to the coating film formed by the coating composition of the Comparative Example. Therefore, the coating composition can form a coating film on leather that is superior in water resistance, stain resistance and stain removability.

[0129] It was also found that the coating films formed by the coating compositions of the examples had low gloss, and that even when a matting agent was added, the coating films had good stain resistance and stain removability.

Claims

1. Particles including a first polymer having a first repeating unit derived from an unsaturated carboxylic acid ester having an alkyl group having 4 or more carbon atoms or a cycloalkyl group having 4 or more carbon atoms and a third repeating unit derived from an unsaturated carboxylic acid; Liquid medium and Contains a content ratio of the first repeating unit to all repeating units constituting the first polymer is 10% by mass or more, The leather coating composition, wherein the particles have an average particle size of 500 nm or more.

2. 2. The leather coating composition according to claim 1, wherein the first repeating unit is derived from an unsaturated carboxylic acid ester having an alkyl group having 4 or more carbon atoms.

3. the first polymer further comprises a second repeating unit derived from an unsaturated carboxylate having an alkyl group having 3 or less carbon atoms, 3. The coating composition for leather according to claim 1, wherein the content of said second repeating unit relative to all repeating units constituting said first polymer is 10% by mass or more.

4. A coating composition for leather as described in claim 1, claim 2 or claim 3, wherein the content ratio of the third repeating unit to the total repeating units constituting the first polymer is 10 mass% or less.

5. The coating composition for leather according to any one of claims 1 to 4, wherein the particles have an average particle size of 500 nm or more and less than 4000 nm.

6. 6. The coating composition for leather according to claim 1, wherein the particles further contain a second polymer having a repeating unit derived from a fluorine-containing ethylene monomer.

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