JP2022127999A - Coating composition for leather - Google Patents

Abstract

To provide a coating composition for leather, capable of forming on a leather surface, a coating film that is excellent in abrasion resistance, can suppress adhesion of dirt, and can easily remove adhering dirt.SOLUTION: A coating composition for leather, containing polymer particles and a liquid medium is such that: the polymer particles contains first polymers having first repeating units derived from tetrafluoroethylene in the same or different polymer particle, and second polymers excluding the first polymers; and a content ratio of the first repeating units to the total repeating units constituting the polymer particles is 20 mass% or more and 70 mass% or less.SELECTED DRAWING: None

Description

The present invention relates to coating compositions for leather.

Leathers such as natural leathers and synthetic leathers are widely used, for example, for automobile interiors, furniture such as sofas, clothing such as coats, and the like. It is known that when dirt such as so-called denim dirt or ballpoint pen dirt adheres to the surface of leather, it is difficult to remove the dirt.

Therefore, coating the surface of the leather makes it easier to remove the dirt (Japanese Patent Application Laid-Open No. 2007-191820).

Japanese Patent Application Laid-Open No. 2007-191820

However, abrasion resistance is also required for the coating applied to the surface of leather.

The present invention has been made based on the above circumstances, and its object is to provide a coating that has excellent wear resistance, can suppress the adhesion of dirt, and can easily remove the dirt that has adhered to the surface of leather. An object of the present invention is to provide a coating composition for leather that can form a film.

An invention made to solve the above problems comprises polymer particles and a liquid medium, wherein the polymer particles contain first repeating units derived from tetrafluoroethylene in the same or different polymer particles. and a second polymer other than the first polymer, and the content of the first repeating unit with respect to all repeating units constituting the polymer particle is 20% by mass or more and 70% by mass or less It is a coating composition for leather.

According to the leather coating composition of the present invention, the leather surface has excellent wear resistance, can suppress the adhesion of dirt (hereinafter also referred to as "excellent dirt resistance"), and easily removes adhered dirt. It is possible to form a coating film that can be removed (hereinafter, also referred to as "excellent in stain removability").

The leather coating composition of the present invention is described in detail below.

The coating composition for leather (hereinafter also simply referred to as "coating composition") comprises polymer particles (hereinafter also referred to as "[A] polymer particles") and a liquid medium (hereinafter referred to as "[B] liquid medium ”). The coating composition may contain a cross-linking agent (hereinafter also referred to as "[C] cross-linking agent"). In addition, the coating composition contains other components (hereinafter also referred to as "other components") other than [A] polymer particles, [B] liquid medium and [C] cross-linking agent, as long as the effects of the present invention are not impaired. ) may be contained.

The coating film formed from the coating composition has excellent abrasion resistance because the first polymer having the first repeating unit derived from tetrafluoroethylene exhibits low friction.
A coating film formed from the coating composition is excellent in stain resistance because a dense film can be formed by emulsion fusion. The film formed from the coating composition has excellent stain removability because the first polymer having the first repeating unit derived from tetrafluoroethylene exhibits low polarity and non-adhesiveness.

Furthermore, the coating film formed by the coating composition has low gloss. Low gloss is often required for coating leather, and the coating composition can form a low gloss coating that meets this requirement. In general, matting agents are added to leather coatings in order to exhibit low glossiness, but the addition of matting agents tends to reduce stain resistance. According to the coating composition, no matting agent is blended or the blending amount of the matting agent can be reduced, so that both stain resistance and low glossiness can be achieved.

Furthermore, the coating film formed from the coating composition has excellent water resistance because the first polymer having the first repeating unit derived from tetrafluoroethylene exhibits water repellency.

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

The leather is not particularly limited, and may be natural leather or synthetic leather. In addition, in this specification, "synthetic leather" means leather other than natural leather. The synthetic leather material is not particularly limited, and examples thereof include polyurethane and polyvinyl chloride. Synthetic leathers include synthetic leathers used for automobile interiors, furniture such as sofas, and clothing such as coats.

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

<[A] polymer particles>
The [A] polymer particles are the same or different from a first polymer (hereinafter also referred to as "polymer (Pa)") having a first repeating unit derived from tetrafluoroethylene in the same or different [A] polymer particles. , and a second polymer other than the first polymer (hereinafter also referred to as “polymer (Pb)”). The coating composition may contain one or more [A] polymer particles.

The [A] polymer particles are usually latex-like particles dispersed in the [B] liquid medium using the [B] liquid medium as a dispersion medium.

[A] The polymer particles may be particles containing the polymer (Pa) and the polymer (Pb) in the same particle, or particles containing the polymer (Pa) and the polymer (Pb) It may be a mixture with particles containing.

The content of the polymer (Pb) in the [A] polymer particles is preferably 10% by mass or more and 90% by mass or less, and 15% by mass or more and 85% by mass, based on the total polymer constituting the [A] polymer particles. % by mass or less is more preferable, and 20% by mass or more and 80% by mass or less is even more preferable.

<Polymer (Pa)>
The polymer (Pa) has a repeating unit derived from tetrafluoroethylene (hereinafter also referred to as "repeating unit (Ia)"). The content of the repeating unit (Ia) in the [A] polymer particles is 20% by mass or more and 70% by mass or less with respect to all repeating units constituting the [A] polymer particles. The polymer (Pa) has a repeating unit (Ia), and by setting the content of the repeating unit (Ia) to a specific range, the leather surface has excellent abrasion resistance, excellent stain resistance, and It is possible to form a coating film with excellent stain removability.

The lower limit of the content of the repeating unit (Ia) in the [A] polymer particles is 20% by mass, preferably 30% by mass, based on the total repeating units constituting the [A] polymer particles. . In this case, a coating film having better abrasion resistance can be formed on the surface of the leather. The upper limit of the content of the repeating unit (Ia) in the [A] polymer particles is 70% by mass, preferably 65% by mass, based on the total repeating units constituting the [A] polymer particles. . In this case, it is possible to form a coating film on the surface of the leather which is more excellent in stain-removing properties.

The lower limit of the content of the repeating unit (Ia) in the polymer (Pa) is preferably 70% by mass, preferably 80% by mass, based on the total repeating units constituting the polymer (Pa). The upper limit of the content of the repeating unit (Ia) in the polymer (Pa) is 100% by mass with respect to all repeating units constituting the polymer (Pa).

The polymer (Pa) preferably further has a repeating unit derived from hexafluoropropylene (hereinafter also referred to as "repeating unit (Ib)"). In this case, it is possible to form a coating film on the surface of the leather which is more excellent in stain-removing properties.

When the polymer (Pa) has the repeating unit (Ib), the lower limit of the content of the repeating unit (Ib) in the polymer (Pa) is 0 with respect to all repeating units constituting the polymer (Pa). .1% by weight is preferred, 1% by weight is preferred. The upper limit of the content of the repeating unit (Ib) in the polymer (Pa) is preferably 30% by mass, more preferably 20% by mass, based on the total repeating units constituting the polymer (Pa).

The polymer (Pa) may have repeating units other than the repeating units (Ia) and (Ib) (hereinafter also referred to as "repeating units (Ic)"). The polymer (Pa) can have one or more repeating units (Ic).

Examples of the monomer that gives the repeating unit (Ic) include fluorine-containing ethylenic monomers, monomers described in International Publication No. 2014/112252, and the like.

As used herein, the fluorine-containing ethylenic monomer is a compound having an ethylenic carbon-carbon double bond and a fluorine atom, and is a compound other than tetrafluoroethylene and hexafluoropropylene. Examples of fluorine-containing ethylene-based monomers include fluoroolefins, fluorochlorinated olefins, (meth)acrylates having a fluorine atom, and perfluoroalkyl vinyl ethers. Examples of fluorinated olefins include vinylidene fluoride and the like. Examples of fluorinated chlorinated olefins include ethylene trifluoride chloride and the like. Examples of the (meth)acrylate having a fluorine atom include compounds represented by the following formula (a), (meth)acrylic acid 3-[4[1-trifluoromethyl-2,2-bis[bis(tri fluoromethyl)fluoromethyl]ethynyloxy]benzooxy]-2-hydroxypropyl and the like. Examples of perfluoroalkyl vinyl ethers include trifluoromethyltrifluorovinyl ether and heptafluoropropyltrifluorovinyl ether.

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

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

<Polymer (Pb)>
Polymer (Pb) is a polymer other than polymer (Pa). By containing the polymer (Pb) in the coating composition, a coating film having excellent adhesion to leather can be formed. [A] The polymer particles can contain one or more polymers (Pb).

Examples of the polymer (Pb) include unsaturated carboxylic acid-based polymers, urethane-based polymers, polyvinyl acetate-based polymers, polyester-based polymers, vinyl chloride-based polymers, and polyamide-based polymers. Among these, the unsaturated carboxylic acid-based polymer or the urethane-based polymer is preferred, and the unsaturated carboxylic acid-based polymer is more preferred, from the viewpoint of improving stain resistance. As the polymer (Pb), a synthesized product or a commercially available product may be used.

[Unsaturated carboxylic acid-based polymer]
Examples of unsaturated carboxylic acid-based polymers include polymers having repeating units derived from alkyl esters of unsaturated carboxylic acids (hereinafter also referred to as “repeating units (IIa)”). The unsaturated carboxylic acid-based polymer can have one or more repeating units (IIa). The unsaturated carboxylic acid-based polymer may have repeating units other than the repeating unit (IIa) (hereinafter also referred to as "other repeating units").

Ethylenically unsaturated carboxylic acids are preferred as the unsaturated carboxylic acids constituting the alkyl esters of unsaturated carboxylic acids. Examples of ethylenically unsaturated carboxylic acids include ethylenically unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid and crotonic acid, and ethylenically unsaturated dicarboxylic acids such as maleic acid, fumaric acid and itaconic acid. Among these, ethylenically unsaturated monocarboxylic acids are preferable, and acrylic acid or methacrylic acid is more preferable.

Examples of alkyl esters of unsaturated carboxylic acids include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, lauryl (meth) acrylate, etc. ( meth) acrylic acid ester; (meth) acrylic acid ester having a branched chain alkyl group such as 2-ethylhexyl (meth) acrylate, i-butyl (meth) acrylate, tert-butyl (meth) acrylate; ) (meth)acrylic acid esters having a cyclic alkyl group such as cyclohexyl acrylate. "(Meth)acrylic acid" is a concept that includes "acrylic acid" and "methacrylic acid".

The lower limit of the content of the repeating unit (IIa) in the unsaturated carboxylic acid-based polymer is preferably 70% by mass, more preferably 85% by mass, based on the total repeating units constituting the unsaturated carboxylic acid-based polymer. . The upper limit of the content ratio is preferably 99% by mass, more preferably 99.9% by mass.

Other repeating units include, for example, unsaturated carboxylic acids, unsaturated carboxylic acid hydroxyalkyl esters, unsaturated carboxylic acid polyalkylene glycol esters, unsaturated carboxylic acid amino group-containing esters, polymerizable group-containing alkoxysilanes, international Examples thereof include repeating units derived from the monomers described in JP-A-2014/112252.

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.

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

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

Examples of the polymerizable group-containing alkoxysilane include compounds represented by the following formula (b).
R ³ _n Si(OR ⁴ ) _4-n (b)

In formula (b) above, R ³ is a monovalent organic group having 1 to 8 carbon atoms. However, at ^least one of R3 has a polymerizable group. R ⁴ is a monovalent organic group having 1 to 8 carbon atoms. n is an integer of 0-3. When R ³ is plural, the plural R ³ are the same or different. When R ⁴ is plural, the plural R ⁴ are the same or different.

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)

In formula (c) above, R ⁵ is a monovalent organic group having 1 to 8 carbon atoms. However, at ^least one of R5 is a group derived from a group having a polymerizable group. m is a number from 0 to 3; When R ⁵ is plural, the plural R ⁵ are the same or different.

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

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, allyl ethers and the like.

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, acrolein and the like.

Alkoxysilanes include, for example, methyltriethoxysilane.

Examples of α,β-unsaturated nitriles include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethylacrylonitrile and the like.

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.

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

Examples of vinyl ether 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, 2-aminoethyl vinyl ether and the like.

Examples of allyl ether 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, propylene glycol monoallyl ether. Allyl ether etc. are mentioned.

When the polymer (Pb) has other repeating units, the lower limit of the content of the other repeating units in the polymer (Pb) is 0.1 with respect to all repeating units constituting the polymer (Pb). % by mass is preferred, and 1% by mass is more preferred. The upper limit of the content ratio is preferably 30% by mass, more preferably 15% by mass.

The lower limit of the content of the [A] polymer particles in the coating composition is preferably 70% by mass, more preferably 85% by mass, based on the total solid content of the coating composition. The upper limit of the content is, for example, 100% by mass, preferably 98% by mass. The “total solid content” of the coating composition refers to the total sum of components other than the [B] liquid medium of the coating composition.

[A] The polymer particles can be produced, for example, by subjecting predetermined monomers to emulsion polymerization according to a known method. For example, it can be synthesized by the method described in International Publication No. 2014/112252.

[[A] Physical properties of polymer particles]
(Average particle size)
[A] The lower limit of the average particle size of the polymer particles is preferably 30 nm, more preferably 50 nm, and even more preferably 80 nm. The upper limit of the average particle size is preferably 10 µm, more preferably 5 µm.

[A] In the present specification, the average particle diameter of the polymer particles is measured by measuring the particle size distribution using a particle size distribution analyzer based on the measurement principle of light scattering, and accumulating the number of particles from small particles. It is the value of the particle diameter (D50) at which the frequency becomes 50%. Examples of such a particle size distribution analyzer include "FPAR-1000" manufactured by Otsuka Electronics Co., Ltd., and the like. The particle size distribution measuring apparatus can evaluate not only the primary particles of the [A] polymer particles, but also the secondary particles formed by aggregation of the primary particles. Therefore, the particle size distribution measured by these particle size distribution analyzers can be used as an indicator of the state of dispersion of the [A] polymer particles contained in the coating composition.

(endothermic peak temperature)
[A] The polymer particles have at least one endothermic peak in the temperature range of −50° C. or more and +80° C. or less when measured by differential scanning calorimetry (DSC) in accordance with JIS-K-7121:2012. is preferred. [A] The temperature of one of the endothermic peaks of the polymer particles is more preferably in the range of -30°C or higher and +70°C or lower, and more preferably in the range of -20°C or higher and +60°C or lower.

(acid value)
[A] The lower limit of the acid value of the polymer particles is 0 mgKOH/g. [A] The upper limit of the acid value of the polymer particles is preferably 100 mgKOH/g, more preferably 80 mgKOH/g, and even more preferably 50 mgKOH/g. As used herein, "acid value" means mg of potassium hydroxide required to neutralize acidic groups contained in 1 g of sample. The acid value of the [A] polymer particles can be adjusted, for example, by adjusting the amount of the monomer having an acid group contained in the polymer constituting the [A] polymer particles.

<[B] liquid medium>
[B] As the liquid medium, an aqueous medium containing water is preferable. This aqueous medium can contain a non-aqueous medium other than water. From the viewpoint of improving the coatability of the coating composition, a non-aqueous medium having a normal boiling point of 60° C. or higher and 350° C. or lower can 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; methanol, ethanol and isopropyl. Alcohols such as alcohol, n-butyl alcohol, isobutyl alcohol, t-butyl alcohol, ethylene glycol, glycerin, propylene glycol, 2-ethyl-1-hexanol, 1-nonanol, lauryl alcohol; methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, phoron ketones such as , 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; γ-butyrolactone lactones such as , δ-valerolactone; sulfoxides such as dimethylsulfoxide; and sulfone compounds such as sulfolane.

When the [B] liquid medium contains water and a non-aqueous medium other than water, the lower limit of the content of water in the [B] liquid medium is preferably 80% by mass, more preferably 90% by mass. [B] By using an aqueous medium as the liquid medium, the coating composition has a lower degree of adverse effects on the environment and a higher level of safety for workers handling it.

<[C] Crosslinking agent>
The coating composition can contain [C] a cross-linking agent. When the coating composition contains the [C] cross-linking agent, the coating film can be densified by cross-linking, and water resistance can be imparted. The [C] cross-linking agent is preferably dissolved in the [B] liquid medium.

Examples of [C] cross-linking agents include hydrazine derivatives, carbodiimide compounds, isocyanate compounds, amino compounds, epoxy compounds, alkoxysilyl group-containing compounds, metal-based cross-linking agents, oxazoline compounds, acid anhydrides, aziridine compounds, and the like.

Examples of hydrazine derivatives include compounds 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 1 mol of the carbonyl group contained in the [A] polymer particles. The upper limit of the content is preferably 1.1 mol, more preferably 1.0 mol. Even if the content of the hydrazine derivative is less than 0.02 mol or more than 1.1 mol with respect to 1 mol of the carbonyl group contained in the [A] polymer particles, the formed coating film Water resistance and solvent resistance may be insufficient.

Hydrazine derivatives having at least two hydrazino groups include, for example, 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, C 2-10, preferably 4-6 dicarboxylic acid dihydrazides such as itaconic acid dihydrazide, carbon such as ethylene-1,2-dihydrazine, propylene-1,3-dihydrazine, butylene-1,4-dihydrazine Aliphatic water-soluble dihydrazines of numbers 2 to 4 and the like can be mentioned. Among these, adipic acid dihydrazide is preferred. The hydrazine derivative has the effect of forming a film with 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 dries and scatters. Although no catalyst is usually used for this cross-linking reaction, water-soluble metal salts such as zinc sulfate, manganese sulfate, and cobalt sulfate can be used as catalysts, if necessary.

Examples of commercially available carbodiimide compounds include "Carbodilite E-02", "E-03A", "E-04", "E-05", and "V-02" available from Nisshinbo Chemical Co., Ltd. "Same SV-02", "Same V-02-L2", "Same V-04", "Same V-10" and the like. Among these, "Carbodilite V-02-L2", "Carbodilite V-02" or "Carbodilite E-05" are preferred.

Specific examples of isocyanate compounds include 2,4-tolylene diisocyanate, diphenylmethane-4,4'-diisocyanate, xylylene diisocyanate, isophorone diisocyanate, lysine methyl ester diisocyanate, methylcyclohexyl diisocyanate, trimethylhexamethylene diisocyanate, and hexamethylene diisocyanate. , n-pentane-1,4-diisocyanate, trimers thereof, adducts and biurets thereof, polymers thereof having two or more isocyanate groups, lysine triisocyanate, blocked isocyanates etc. Examples of commercially available isocyanate compounds include "Duranate WT30-100" manufactured by Asahi Kasei Corporation.

Specific examples of epoxy compounds include epoxy resins and epoxy-modified silane coupling agents.

Specific examples of alkoxysilyl group-containing compounds include methyltrimethoxysilane, methyltriethoxysilane, phenyltrimethoxysilane, 3-trimethoxysilylpropylsuccinic anhydride, 3-isocyanatopropyltriethoxysilane, tris-(tri methoxysilylpropyl)isocyanurate and the like.

Specific examples of metal-based cross-linking agents include organic titanium compounds such as titanium lactate, and zirconium compounds such as ammonium zirconium carbonate.

When the coating composition contains the [C] cross-linking agent, the lower limit of the content of the [C] cross-linking agent is preferably 0.1 parts by mass with respect to 100 parts by mass of the [A] polymer particles. Parts by mass are more preferred. The upper limit of the content is preferably 20 parts by mass, more preferably 10 parts by mass.

[C] The method of adding the cross-linking agent includes, for example, [C] a method of dissolving or dispersing the cross-linking agent in water and adding it to the coating composition, [C] dissolving the cross-linking agent in a small amount of water-soluble organic solvent. [C] a method of adding a cross-linking agent directly to the coating composition, and the like.

<Other optional ingredients>
The coating composition may optionally contain other optional components than [A] polymer particles, [B] liquid medium and [C] cross-linking agent. Other optional components include, for example, matting agents, water-based urethane resins, fillers, surface preparation agents, weather resistance improvers, thickeners, antifoaming agents, film forming aids, antifreezing agents, pH adjusters, wetting agents, property improvers, pigments and the like. These can also use a commercial item. The coating composition may contain one or more other optional ingredients.

As a method of adding other optional components, for example, a method of dissolving or dispersing other optional components in water and adding them to the coating composition, or dissolving other optional components in a small amount of water-soluble organic solvent. to the composition, a method of directly adding other optional components to the composition, and a method of adding [A] to the polymerization system when synthesizing the polymer particles.

EXAMPLES The present invention will be specifically described below based on Examples, but the present invention is not limited to these Examples.

<[A] Synthesis of polymer particles>
[A] The abbreviations of the components used in the synthesis of the polymer particles are shown below.
TFE: tetrafluoroethylene HFP: hexafluoropropylene VDF: vinylidene fluoride CTFE: chlorotrifluoroethylene EHA: 2-ethylhexyl acrylate BA: butyl acrylate CHMA: cyclohexyl methacrylate MMA: methyl methacrylate AA: acrylic acid MAA: meta Acrylic acid HEMA: 2-hydroxyethyl methacrylate

In the synthesis examples below, unless otherwise specified, "parts by mass" means the value when the total mass of the monomers used is 100 parts by mass.

[Synthesis Example 1] Synthesis of particles (S1) After sufficiently replacing the inside of an autoclave with an internal volume of about 6 L equipped with an electromagnetic stirrer with nitrogen, 2.5 L of deoxygenated pure water and ammonium perfluorodecanoate as an emulsifier 25 g was charged, and the temperature was raised to 60° C. while stirring at 350 rpm. Next, a gas containing 100 parts by mass of tetrafluoroethylene (TFE), which is a monomer, was charged until the internal pressure reached 20 kg/cm ² . 25 g of a Freon 113 solution containing 20% by mass of diisopropyl peroxydicarbonate as a polymerization initiator was pressurized using nitrogen gas to initiate polymerization. During the polymerization, 100 parts by mass of TFE gas was successively injected so that the internal pressure was maintained at 20 kg/cm ² to maintain the pressure at 20 kg/cm ² . In addition, since the polymerization rate decreased as the polymerization progressed, after 3 hours, the same amount of the same polymerization initiator solution as before was pressurized using nitrogen gas, and the reaction was further continued for 3 hours. After that, the reaction solution is cooled and the stirring is stopped, and the reaction is stopped after releasing the unreacted monomer, thereby obtaining an aqueous dispersion containing 40% by mass of the particles (S1) of the polymer (Pa). Obtained.

[Synthesis Examples 2 and 3] Synthesis of Particles (S2) and (S3) A polymer (Pa) 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. Then, an aqueous dispersion containing 40% by mass of particles (S2) and (S3) was obtained.

[Synthesis Example 4] Synthesis of particles (S4) After sufficiently replacing the inside of an autoclave with an internal volume of about 6 L equipped with an electromagnetic stirrer with nitrogen, 2.5 L of deoxygenated pure water and ammonium perfluorodecanoate as an emulsifier 10 g was charged, and the temperature was raised to 60° C. while stirring at 350 rpm. Next, a gas containing 100 parts by mass of tetrafluoroethylene (TFE), which is a monomer, was charged until the internal pressure reached 20 kg/cm ² . 10 g of Freon 113 solution containing 20% by mass of diisopropyl peroxydicarbonate as a polymerization initiator was pressurized using nitrogen gas to initiate polymerization. During the polymerization, 100 parts by mass of TFE gas was successively injected so that the internal pressure was maintained at 20 kg/cm ² to maintain the pressure at 20 kg/cm ² . In addition, since the polymerization rate decreased as the polymerization progressed, after 3 hours, the same amount of the same polymerization initiator solution as before was pressurized using nitrogen gas, and the reaction was further continued for 3 hours. After that, the reaction solution is cooled, stirring is stopped, and the reaction is stopped after unreacted monomers are released, thereby obtaining an aqueous dispersion containing 40% by mass of polymer (Pa) particles (S4). Obtained.

[Synthesis Example 5] Synthesis of Particles (S5) A polymer (Pa) 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. Next, after the interior of the separable flask was sufficiently replaced with nitrogen, 583 parts by mass of an aqueous dispersion containing fine particles of the polymer (Pa) synthesized above (polymer (Pa) 233 parts by mass), polyoxyethylene dodecyl ether 1 part by mass of sodium sulfate and 40 parts by mass of water were charged. In a separate container, 44 parts by mass of 2-ethylhexyl acrylate (EHA), 44 parts by mass of methyl methacrylate (MMA), 44 parts by mass of methyl methacrylate (MMA), and methacrylic acid (MAA) were added to 233 parts by mass of the polymer (Pa) contained in the aqueous dispersion. ), 2 parts by weight of an emulsifier (“Adekari Soap SR10” manufactured by ADEKA Co., Ltd.) and 80 parts by weight of water were mixed and sufficiently stirred to prepare a monomer emulsion. Thereafter, the temperature of the separable flask was started to rise 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 reaches 75°C, the addition of the monomer emulsion prepared above is started, and the monomer emulsion is added for 2 hours while maintaining the internal temperature of the separable flask at 75°C. was added slowly over a period of time. 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 to polymerize the polymer (Pb). After that, the separable flask is cooled to stop the reaction, aqueous ammonia is added to adjust the pH to 7.6, water is added to adjust the solid content concentration, and water containing 40% by mass of particles (S5) A dispersion was obtained.

[Synthesis Examples 6 to 10] Synthesis of Particles (S6) to (S10) Polymer (Pa) and polymer were prepared in the same manner as in Synthesis Example 5 except that the types and amounts of monomers shown in Table 1 below were used. Combined (Pb) was synthesized to obtain an aqueous dispersion containing 40% by mass of particles (S6) to (S10).

[Synthesis Example 10] Synthesis of Particles (S11) In a reaction vessel, 51 parts by mass of butyl acrylate (BA), 45 parts by mass of methyl methacrylate (MMA), 2 parts by mass of acrylic acid (AA), and 2-hydroxyethyl methacrylate were added. 2 parts by mass of (HEMA), 1.8 parts by mass of an emulsifier (“Adekari Soap SR1025” manufactured by ADEKA Co., Ltd.) and 100 parts by mass of water were charged and sufficiently stirred to prepare a monomer emulsion. After charging 50 parts by mass of water in a separable flask, the temperature was started to rise in a water bath, and when the internal temperature of the separable flask reached 50 ° C., 0.3 parts by mass of ammonium persulfate as a polymerization initiator was added. When the internal temperature of the separable flask reached 75°C, the addition of the monomer emulsion was started, and the monomer emulsion was added over 2 hours while maintaining the internal temperature of the separable flask at 75°C. was added slowly. 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 to polymerize the polymer (Pb). After that, the separable flask is cooled to stop the reaction, ammonia water is added to adjust the pH to 7.6, water is added to adjust the solid content concentration, and the polymer (Pb) particles (S11) are obtained. An aqueous dispersion containing 40% by mass was obtained.

<[A] Physical properties of polymer particles>
The average particle size, endothermic peak temperature and acid value of the [A] polymer particles synthesized above were measured by the following methods. The results are also shown in Table 1 below.

[Average particle size]
The resulting aqueous dispersion was measured for particle size distribution using a particle size distribution analyzer ("FPAR-1000" by Otsuka Electronics Co., Ltd.) based on the dynamic light scattering method, and the average particle size was determined from the particle size distribution. A diameter (D50) was obtained.

[Endothermic peak temperature]
The resulting water dispersion was measured with a differential scanning calorimeter (DSC) to observe an endothermic peak.

[Acid value]
About 10 g of the resulting aqueous dispersion is weighed into a Teflon (registered trademark) petri dish with a diameter of 8 cm and dried at 120 ° C. for 1 hour to form a film, based on JIS-K-0070 (1992). Acid value was measured.

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

<Preparation of coating composition and formation of coating>
Each component used for preparation of the composition is shown below.

As the polymer (Pb), an aqueous dispersion containing 38% by mass of particles (S12) of an aqueous urethane resin (“Superflex 460” manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) was used.

[[C] cross-linking agent]
[C] “Carbodilite V-04” manufactured by Nisshinbo Chemical Co., Ltd. was used as a cross-linking agent.

[Other ingredients]
As a matting agent, "ACEMATT TS100" from Evonik was used.

[Example 1] Preparation of coating composition (T1) and formation of coating film [A] 250 parts by mass of aqueous dispersion containing particles (S5) as polymer particles (containing 100 parts by mass of particles (S5)) A coating composition (T1) was prepared by adding [C] 5 parts by mass of a cross-linking agent and 10 parts by mass of a matting agent and stirring at 300 rpm. 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 dried at 120° C. for 2 minutes to form a coating film.

[Examples 2 to 10 and Comparative Examples 1 to 4]
Coating compositions (T2) to (T10) and (CT1) to (CT3) were prepared in the same manner as in Example 1 except that the types and amounts of each component shown in Table 2 below were used to form a coating film. did.

<Evaluation>
The coating film thus formed was evaluated for wear resistance, stain resistance, stain removability, glossiness and water resistance according to the following methods. The results are shown in Table 2 below. In Table 2 below, "-" in the "Evaluation Results" row indicates that in Comparative Example 4, the evaluation test could not be performed due to the peeling of the coating film from the leather during the evaluation test.

[Abrasion resistance]
The dynamic friction coefficient between the coating film and BEMCOT was measured according to JIS-K-7125 (1999) using a tester ("TENSILON RTG-1210" manufactured by A&D Co., Ltd.). If the dynamic friction coefficient is less than 0.5, it is "A" (very good), if it is 0.5 or more and less than 0.6, it is "B" (good), and if it is 0.6 or more and less than 0.7, it is "C" (slightly good), "D" (poor) when 0.7 or more and less than 0.8, and "E" (extremely poor) when 0.8 or more.

[Stain resistance]
The above coating film is set on the curved surface of a Gakushin rubbing fastness tester (“RT-300” by Daiei Kagaku Seiki Seisakusho Co., Ltd.), and a contaminated cloth (DENIM 2550Y) and a weight of 500 g are attached. A dirt friction test of 100 reciprocations was performed with a child. The Lab values before and after the staining friction test were measured with a handy type color difference meter ("CM-700d" by Konica Minolta, Inc.), and the color difference ΔE was calculated. The stain resistance is "A" (extremely good) when ΔE is less than 5, "B" (good) when ΔE is 5 or more and less than 7, and "C" (slightly good) when ΔE is 7 or more and less than 9. and "D" (poor) when 9 or more and less than 11, and "E" (extremely poor) when 11 or more.

[Stain removal]
After the staining friction test in the "stain resistance" test, the coating film was wiped with water by hand using BEMCOT wetted with water, and the end point was the time when no contamination remained on the BEMCOT side. The Lab value after wiping with water was measured in the same manner as in the above "stain resistance" test, and the color difference ΔE was calculated using the Lab value before the staining rubbing test. The stain removability is "A" (extremely good) when ΔE is less than 3, "B" (very good) when ΔE is 3 or more and less than 5, and "C" (good) when 5 or more and less than 7. and "D" (poor) when 7 or more and less than 9, and "E" (extremely poor) when 9 or more.

[Glossiness]
The 60° gloss was measured using a gloss meter (BYK's "micro-TRI-gloss") before the "smudge resistance" test. For 60° gloss, the lower the number, the lower the gloss. The glossiness is "A" (very good) when the 60° gloss is less than 3, "B" (very good) when it is 3 or more and less than 5, and "C" (good) when it is 5 or more and less than 7 ), "D" (poor) when 7 or more and less than 9, and "E" (extremely poor) when 9 or more.

[water resistant]
The coating film is set on the curved surface of the Gakushin type rubbing fastness tester ("RT-300" by Daiei Kagaku Seiki Seisakusho Co., Ltd.), and is attached with a water-wet Bemcot and a 300g load weight. A friction test of 10 reciprocations was performed. The coating film before and after the friction test was visually observed to evaluate the water resistance. Water resistance is rated as "A" (extremely good) if there is no change in appearance, "B" (good) if a little loss of luster is observed, and "C" (slightly good) if the loss of luster is large. When the coating film was partially peeled off, it was evaluated as "D" (poor), and when the coating film was not left, it was evaluated as "E" (extremely poor).

From the results in Table 2, the coating films formed from the coating compositions of Examples are superior in wear resistance, stain resistance and stain removability to the coating films formed from the coating compositions of Comparative Examples. It became clear.

Furthermore, it was found that the coating films formed from the coating compositions of Examples had low glossiness and excellent water resistance.

Claims (5)

polymer particles;
containing a liquid medium and
wherein the polymer particles contain, in the same or different polymer particles, a first polymer having a first repeating unit derived from tetrafluoroethylene and a second polymer other than the first polymer;
A coating composition for leather, wherein the content of the first repeating units is 20% by mass or more and 70% by mass or less with respect to all repeating units constituting the polymer particles. 2. The coating composition for leather according to claim 1, wherein the content of said first repeating units is 30% by mass or more relative to all repeating units constituting said polymer particles. 3. The coating composition for leather according to claim 1, wherein the content of the first repeating units is 65% by mass or less with respect to all repeating units constituting the polymer particles. 4. The coating composition for leather according to claim 1, 2 or 3, wherein the first polymer further has a second repeating unit derived from hexafluoropropylene. 5. The coating composition for leather according to any one of claims 1 to 4, wherein the second polymer has a third structural unit derived from an unsaturated carboxylic acid ester.