1. Composition of liquid-curing coating

Abstract

To provide a one-component curing paint composition that exhibits excellent coating performance, including weather resistance, coating hardness, chemical resistance, and impact resistance. [Solution] A one-component curable paint composition containing a vinyl polycarboxylic acid resin (A) having a glass transition temperature of 0°C to 100°C, an epoxy group-containing silane coupling agent (B), and a hydrolyzable silyl group-containing silicone resin (C). In particular, a one-component curable paint composition in which the solubility parameter of the vinyl polycarboxylic acid resin (A) is in the range of 7 to 10. A painting method for applying the one-component curable paint composition. Exterior building material coated with the one-component curing paint composition.

Description

Technical Field

[0001] The present invention relates to a one-component curable coating composition having excellent coating film properties such as weather resistance, coating film hardness, chemical resistance, and impact resistance.

Background Art

[0002] In the case of paints for exterior building materials where high levels of weather resistance are required, fluororesin-based coating compositions have been used until now. However, it is expected that the use of fluororesins will become difficult in the future due to regulations such as PFAS regulations and the supply instability of fluororesins. On the other hand, there are silicone resin-based paints as high weather resistance materials to replace fluororesins, and they have attracted attention as high weather resistance materials to replace fluororesins.

[0003] Patent Document 1 aims to provide a coating composition capable of forming a coating film excellent in corrosion resistance and weather resistance at room temperature and in a single coating process for the purpose of corrosion prevention and aesthetic maintenance of steel structures in anticorrosive coating. A coating composition containing an acrylic resin, an epoxy resin having at least two epoxy groups in one molecule, an amine curing agent that may contain an aminosilane, and a curing catalyst is disclosed.

[0004] Further, Patent Document 2 discloses a weather-resistant coating composition containing a hydrolyzable silyl group-containing fluororesin, a hydrolyzable silyl group-containing acrylic resin, and a hydrolyzable silyl group-containing silicone resin as a weather-resistant coating composition capable of forming a coating film excellent in thick film coating properties and long-term weather resistance.

[0005] According to the coating composition as described in Patent Document 1 or 2, a coating film excellent in weather resistance and corrosion resistance can be obtained, so that the aesthetics can be maintained over a long period when applied to steel structures and the like.

[0006] However, the paint compositions described in Patent Documents 1 and 2 are essentially two-component, air-drying, and a one-component specification required for exterior building material coatings presents challenges in terms of paint storage stability. Furthermore, high levels of coating film performance are required in areas not found in applications such as steel structures, including chemical resistance, and coating film hardness is also necessary. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2004-051943 [Patent Document 2] Special Publication No. 2012-128223 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] The problem that this invention aims to solve is to provide a one-component curing type paint composition that has excellent coating performance, such as weather resistance, coating hardness, chemical resistance, and impact resistance. [Means for solving the problem]

[0009] As a result of diligent research, the present inventors have found that the above problems can be solved by a one-component curable coating composition containing a vinyl polycarboxylic acid resin (A) having a glass transition temperature of 0°C to 100°C, an epoxy group-containing silane coupling agent (B), and a hydrolyzable silyl group-containing silicone resin (C), and have completed the present invention.

[0010] In other words, the present invention is 1. A one-component curable coating composition containing a vinyl polycarboxylic acid resin (A) having a glass transition temperature of 0°C to 100°C, an epoxy group-containing silane coupling agent (B), and a hydrolyzable silyl group-containing silicone resin (C).

[0011] 2. The one-component curable coating composition according to item 1 above, wherein the solubility parameter of the vinyl polycarboxylic acid resin (A) is in the range of 7 to 10.

[0012] 3. A one-component curing paint composition according to item 1 or 2 above, further containing a curing catalyst (D).

[0013] 4. A one-component curable paint composition according to any one of items 1 to 3 above, further containing a pigment (E).

[0014] 5. A painting method comprising applying a one-component curing paint composition described in any one of items 1 to 4 above to an object to be painted.

[0015] 6. Relating to exterior building materials coated with a one-component curing paint composition described in any one of items 1 to 4 above. [Effects of the Invention]

[0016] The crosslinking configuration of the coating composition of the present invention is achieved through acid-epoxy crosslinking, in which the carboxyl groups of the vinyl polycarboxylic acid resin react with the epoxy groups of the epoxy group-containing silane coupling agent to form crosslinks. Furthermore, the epoxy group-containing silane coupling agent and the hydrolyzable silyl group-containing silicone resin also undergo a condensation reaction to form crosslinks via siloxane bonds, resulting in a crosslinking configuration that integrates the entire bulk material, thus achieving a one-component system.

[0017] Furthermore, it is presumed that the hydrolyzable silyl group-containing silicone resin component is concentrated and unevenly distributed on the surface of the coating film, resulting in particularly excellent coating film performance, including weather resistance. Therefore, the coating composition of the present invention can provide a one-component curing type coating composition that is excellent in coating film performance such as weather resistance, coating film hardness, chemical resistance, and impact resistance. [Modes for carrying out the invention]

[0018] The one-component curable coating composition of the present invention (hereinafter, may be simply abbreviated as "this coating") is a one-component curable coating composition containing a vinyl polycarboxylic acid resin (A), an epoxy group-containing silane coupling agent (B), and a hydrolyzable silyl group-containing silicone resin (C). Details will be described below.

[0019] <Vinyl polycarboxylic acid resin (A)> The vinyl polycarboxylic acid resin (A) is a vinyl polycarboxylic acid resin containing a carboxy group and / or a cyclic acid anhydride group.

[0020] Specifically, for example, a (co)polymer obtained by radical polymerization of a carboxy group-containing vinyl monomer ((meth)acrylic acid, an adduct of a hydroxyl group-containing vinyl monomer and maleic anhydride, etc.) and, if necessary, other vinyl monomers; a (co)polymer obtained by radical polymerization of an acid anhydride group-containing vinyl monomer and, if necessary, the other vinyl monomers, and then half-esterified with an alcohol (acetol, allyl alcohol, propargyl alcohol, methanol, etc.) (here, half-esterification means a reaction in which a monoalcohol is added to an acid anhydride group and the ring is opened. By half-esterification, a group consisting of a carboxy group and a carboxylic acid ester group is formed. Hereinafter, this group may be simply referred to as a half-ester group.); a (co)polymer obtained by radical polymerization of a half-ester group-containing vinyl monomer and, if necessary, the other vinyl monomers; a hydroxyl group-containing (co)polymer obtained by radical (co)polymerization of a hydroxyl group-containing vinyl monomer as an essential component and, if necessary, the other vinyl monomers, and then half-esterified with an acid anhydride compound (succinic anhydride, etc.).

[0021] Examples of the half-ester group-containing vinyl monomer include a compound obtained by half-esterifying the acid anhydride group of an acid anhydride group-containing vinyl monomer, and a compound obtained by adding an acid anhydride to a hydroxyl group-containing vinyl monomer by half-esterification.

[0022] Examples of compounds obtained by half-esterifying the acid anhydride group of an acid anhydride-containing vinyl monomer include, for example, esterified products of an acid anhydride-containing vinyl monomer such as maleic anhydride or itaconic anhydride with an alcohol (such as acetol, allyl alcohol, propagyl alcohol, or methanol).

[0023] Specific examples of compounds obtained by adding an acid anhydride to a hydroxyl group-containing vinyl monomer by half-esterification include compounds obtained by adding an acid anhydride such as phthalic anhydride or hexahydrophthalic anhydride to a hydroxyl group-containing vinyl monomer as exemplified below by half-esterification.

[0024] Half-esterification can be carried out either before or after the copolymerization reaction, as described above. Examples of monoalcohols used for half-esterification include low molecular weight monoalcohols such as methanol, ethanol, isopropanol, tert-butanol, isobutanol, ethylene glycol monomethyl ether, and ethylene glycol monoethyl ether. The half-esterification reaction can be carried out according to conventional methods at temperatures ranging from room temperature to about 80°C, using a tertiary amine as a catalyst if necessary.

[0025] Examples of vinyl monomers used in vinyl polycarboxylic acid resin (A) include carboxyl group-containing vinyl monomers, acid anhydride-containing vinyl monomers, and other vinyl monomers as needed.

[0026] Carboxylate-containing vinyl monomers are compounds having one or more carboxylate groups and polymerizable unsaturated bonds in one molecule. Specifically, examples include carboxylate-containing polymerizable unsaturated monomers such as (meth)acrylic acid, maleic acid, crotonic acid, itaconic acid, fumaric acid, allyloxypropionic acid, 2-(meth)acryloylethyl succinic acid, 3-butenoic acid, 4-pentenoic acid, 2-hexenoic acid, 3-hexenoic acid, 5-hexenoic acid, 2-heptenoic acid, 3-heptene, 3-octonic acid, 2-nonenic acid, 3-nonenic acid, 9-decenoic acid, 10-undecenoic acid, 2-tridecenoic acid, and β-carboxyethyl acrylate. These can be used individually or in combination of two or more.

[0027] Among the carboxyl group-containing vinyl monomers mentioned above, (meth)acrylic acid can be suitably used from the viewpoint of coating film performance such as weather resistance, coating film hardness, chemical resistance, and impact resistance.

[0028] Examples of vinyl monomers containing acid anhydrides include itaconic anhydride and maleic anhydride.

[0029] Among the above-mentioned acid anhydride-containing vinyl monomers, maleic anhydride can be suitably used from the viewpoint of coating film performance such as weather resistance, coating film hardness, chemical resistance, and impact resistance.

[0030] Other vinyl monomers include, for example, hydroxyl group-containing vinyl monomers; (meth)acrylic acid esters; vinyl ethers and allyl ethers; olefin compounds and diene compounds; hydrocarbon ring-containing vinyl monomers; nitrogen-containing vinyl monomers, etc.

[0031] Examples of hydroxyl group-containing vinyl monomers include: hydroxyalkyl esters of acrylic acid or methacrylic acid having 2 to 8 carbon atoms, such as 2-hydroxyethyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate; monoesters of polyether polyols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol with unsaturated carboxylic acids such as (meth)acrylic acid; monoethers of polyether polyols such as polyethylene glycol, polypropylene glycol, and polybutylene glycol with hydroxyl group-containing unsaturated monomers such as 2-hydroxyethyl (meth)acrylate; and acid anhydride-containing compounds such as maleic anhydride and itaconic anhydride. Examples include diesterified compounds of unsaturated compounds with glycols such as ethylene glycol, 1,6-hexanediol, and neopentyl glycol; hydroxyalkyl vinyl ethers such as hydroxyethyl vinyl ether; allyl alcohol, etc.; 2-hydroxypropyl (meth)acrylate; adducts of α,β-unsaturated carboxylic acids with monoepoxy compounds such as Cardura E10 (a trade name of Shell Petrochemical Corporation) and α-olefin epoxides; adducts of glycidyl (meth)acrylate with monobasic acids such as acetic acid, propionic acid, p-tert-butylbenzoic acid, and fatty acids; and adducts of the above hydroxyl group-containing monomers with lactones (e.g., ε-caprolactone, γ-valerolactone).

[0032] In this specification, "(meth)acrylate" means "acrylate or methacrylate." Also, "(meth)acrylic acid" means "acrylic acid or methacrylic acid." Also, "(meth)acrylamide" means "acrylamide or methacrylamide."

[0033] Examples of (meth)acrylic acid esters include methyl (meth)acrylate, ethyl (meth)acrylate, n-propyl (meth)acrylate, i-propyl (meth)acrylate, n-butyl (meth)acrylate, i-butyl (meth)acrylate, tert-butyl (meth)acrylate, n-hexyl (meth)acrylate, n-octyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, nonyl (meth)acrylate, tridecyl (meth)acrylate, lauryl (meth)acrylate, steryl (meth)acrylate, and steryl (meth)acrylate. Examples include allyl (meth)acrylate, isostearyl acrylate (trade name, manufactured by Osaka Organic Chemical Industry Co., Ltd.), alkyl or cycloalkyl (meth)acrylates such as cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, and cyclododecyl (meth)acrylate; vinyl monomers having an isobornyl group such as isobornyl (meth)acrylate; vinyl monomers having an adamantyl group such as adamantyl (meth)acrylate; and the like.

[0034] Examples of vinyl ethers and allyl ethers include linear alkyl vinyl ethers such as ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, butyl vinyl ether, tert-butyl vinyl ether, pentyl vinyl ether, hexyl vinyl ether, and octyl vinyl ether; cycloalkyl vinyl ethers such as cyclopentyl vinyl ether and cyclohexyl vinyl ether; allyl vinyl ethers such as phenyl vinyl ether and trivinyl ether; aralkyl vinyl ethers such as benzyl vinyl ether and phenethyl vinyl ether; and allyl ethers such as allyl glycidyl ether and allyl ethyl ether.

[0035] Examples of olefin compounds and diene compounds include ethylene, propylene, butylene, vinyl chloride, butadiene, isoprene, and chloroprene.

[0036] Examples of hydrocarbon ring-containing vinyl monomers include styrene, α-methylstyrene, and vinyltoluene.

[0037] Examples of nitrogen-containing vinyl monomers include nitrogen-containing alkyl (meth)acrylates such as N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, and N-tert-butylaminoethyl (meth)acrylate; polymerizable amides such as acrylamide, methacrylamide, N-methyl (meth)acrylamide, N-ethyl (meth)acrylamide, N,N-dimethylN,N-dimethylaminopropyl (meth)acrylamide, and N,N-dimethylaminoethyl (meth)acrylamide; aromatic nitrogen-containing monomers such as 2-vinylpyridine, 1-vinyl-2-pyrrolidone, and 4-vinylpyridine; polymerizable nitriles such as acrylonitrile and methacrylonitrile; allylamines; and adducts of glycidyl (meth)acrylate with amine compounds.

[0038] Furthermore, other vinyl monomers include, for example, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris(2-methoxyethoxy)silane, γ-(meth)acryloyloxypropyltrimethoxysilane, and γ-(meth)acryloyloxypropyltriethoxysilane, which are vinyl monomers having an alkoxysilyl group; Perfluoroalkyl (meth)acrylates such as perfluorobutylethyl (meth)acrylate and perfluorooctylethyl (meth)acrylate; vinyl monomers having fluorinated alkyl groups such as fluoroolefins; Polymerizable unsaturated monomers having photopolymerizable functional groups such as maleimide groups; Vinyl compounds such as ethylene, butadiene, chloroprene, vinyl propionate, and vinyl acetate; Vinyl monomers having two or more polymerizable unsaturated groups in one molecule, such as allyl(meth)acrylate and 1,6-hexanediol(meth)acrylate; Epoxy group-containing vinyl monomers such as glycidyl (meth)acrylate, β-methylglycidyl (meth)acrylate, 3,4-epoxycyclohexylmethyl (meth)acrylate, 3,4-epoxycyclohexylethyl (meth)acrylate, 3,4-epoxycyclohexylpropyl (meth)acrylate, and allyl glycidyl ether; (Meth)acrylates having polyoxyalkylene chains with alkoxy groups at their molecular ends; Vinyl monomers having sulfonic acid groups, such as 2-acrylamido-2-methylpropanesulfonic acid, allylsulfonic acid, sodium styrenesulfonate, sulfoethyl methacrylate and its sodium and ammonium salts; Vinyl monomers having a phosphate group, such as 2-acryloyloxyethyl acid phosphate, 2-methacryloyloxyethyl acid phosphate, 2-acryloyloxypropyl acid phosphate, and 2-methacryloyloxypropyl acid phosphate; Vinyl monomers having UV-absorbing functional groups, such as 2-hydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2-hydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-methacryloyloxy-2-hydroxypropoxy)benzophenone, 2,2'-dihydroxy-4-(3-acryloyloxy-2-hydroxypropoxy)benzophenone, and 2-(2'-hydroxy-5'-methacryloyloxyethylphenyl)-2H-benzotriazole; UV-stable vinyl monomers such as 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2,2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, and 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine; Examples include acrolein, diacetone acrylamide, diacetone methacrylamide, acetoacetoxyethyl methacrylate, formyl styrene, and vinyl monomers having a carbonyl group such as vinyl alkyl ketones having 4 to 7 carbon atoms (e.g., vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone).

[0039] These can be used individually or in combination of two or more types.

[0040] The copolymerization of the above vinyl monomers can be carried out by conventional methods, but considering versatility and cost, solution-type radical polymerization in organic solvents is the most suitable method. Specifically, the desired polymer can be easily obtained by carrying out a copolymerization reaction in a solvent such as an aromatic solvent such as xylene or toluene; a ketone solvent such as methyl ethyl ketone or methyl isobutyl ketone; an ester solvent such as ethyl acetate, butyl acetate, isobutyl acetate, or 3-methoxybutyl acetate; or an alcohol solvent such as n-butanol or isopropyl alcohol, in the presence of a polymerization initiator such as azobisisobutyronitrile or benzoyl peroxide, within a temperature range of approximately 60 to 150°C.

[0041] In vinyl polycarboxylic acid resin (A), when using vinyl monomers containing half-ester groups or vinyl monomers containing acid anhydride groups, the copolymerization amounts of the vinyl monomers containing half-ester groups or acid anhydride groups and other vinyl monomers are usually appropriate in the following proportions of the total monomers. Specifically, the vinyl monomers containing half-ester groups or acid anhydride groups are preferably about 5 to 40% by mass, and particularly 10 to 30% by mass, from the viewpoint of curability and storage stability. The other vinyl monomers are preferably about 60 to 95% by mass, and particularly 70 to 90% by mass. As mentioned above, when using vinyl monomers containing acid anhydride groups, a half-esterification reaction is carried out after the copolymerization reaction.

[0042] From the viewpoint of workability and coating film performance, the vinyl polycarboxylic acid resin (A) preferably has a weight-average molecular weight in the range of 3,000 to 100,000, particularly 5,000 to 80,000, and even more preferably 10,000 to 50,000.

[0043] The "weight-average molecular weight" in the specification is a value calculated based on the molecular weight of standard polystyrene from a chromatogram measured by gel permeation chromatography, in accordance with the method described in JIS K 0124-2011.

[0044] A gel permeation chromatograph, "HLC8120GPC" (manufactured by Tosoh Corporation), was used. Four columns were used: "TSKgel G-4000HXL," "TSKgel G-3000HXL," "TSKgel G-2500HXL," and "TSKgel G-2000HXL" (all manufactured by Tosoh Corporation, product names). Measurements could be performed under the following conditions: mobile phase; tetrahydrofuran, measurement temperature; 40°C, flow rate; 1 ml / min, detector; radioisotope (RI).

[0045] The vinyl polycarboxylic acid resin (A) is preferably in the range of 10 to 200 mgKOH / g, particularly 30 to 180 mgKOH / g, and even more preferably 50 to 100 mgKOH / g, from the viewpoint of curability and finished appearance.

[0046] Furthermore, from the viewpoint of coating hardness, chemical resistance, impact resistance, and weather resistance, the vinyl polycarboxylic acid resin (A) preferably has a glass transition temperature (Tg point) of 0 to 100°C, particularly within the range of 20 to 80°C, and more preferably within the range of 30 to 60°C.

[0047] In this specification, the glass transition temperature (absolute temperature) of an acrylic resin is the value calculated by the following formula.

[0048] 1 / Tg = W1 / T1 + W2 / T2 + ...Wn / Tn In the formula, W1, W2...Wn are the mass % of each monomer [= (amount of each monomer / total mass of monomers) × 100], and T1, T2...Tn are the glass transition temperatures (absolute temperatures) of the homopolymers of each monomer. The glass transition temperatures of the homopolymers of each monomer are values ​​from the Polymer Hand Book (4th Edition). For the glass transition temperatures of homopolymers of monomers not listed in that document, a sample of the homopolymer of the monomer synthesized to have a weight-average molecular weight of approximately 50,000 is used, and its glass transition temperature is measured using differential scanning thermal analysis "DSC-50Q" (product name, manufactured by Shimadzu Corporation). The sample is placed in a measuring cup, the solvent is removed by vacuum suction, and the change in heat quantity is measured in the range of -100°C to +100°C at a heating rate of 3°C / min, and the change point of the first baseline on the lower temperature side is used.

[0049] Furthermore, from the viewpoint of compatibility with silicone resin (C), boiling water resistance, and alkali resistance, it is preferable that the vinyl polycarboxylic acid resin (A) has a solubility parameter (SP value) in the range of 7 to 10, particularly 7 to 9, and even more particularly 8 to 9.

[0050] The solubility parameter of a resin is numerically quantified based on turbidity measurement methods known to those skilled in the art, and specifically, it can be determined according to the formula of KWSUH and JMCORBETT (Journal of Applied Polymer Science, 12, 2359, 1968).

[0051] Vinyl polycarboxylic acid resin (A) can be used alone or in combination of two or more types.

[0052] <Epoxy group-containing silane coupling agent (B)> In the present invention, the epoxy group-containing silane coupling agent (B) is a component that contributes to the integral crosslinking of the coating composition of the present invention by crosslinking with both the vinyl polycarboxylic acid resin (A) and the hydrolyzable silyl group-containing silicone resin (C).

[0053] The epoxy group-containing silane coupling agent (B) is a compound having both an alkoxysilyl group and an epoxy group in its molecule. Specific examples include glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, β-glycidoxyethyltrimethoxysilane, β-glycidoxyethyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyl(methyl)dimethoxysilane, γ-glycidoxypropyl(dimethyl)methoxysilane, γ-glycidoxypropyl(ethyl)dimethoxysilane, (3,4-epoxycyclohexyl)methyltrimethoxysilane, and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane.

[0054] As the epoxy group-containing silane coupling agent (B), γ-glycidoxypropyltrimethoxysilane and γ-glycidoxypropyltriethoxysilane can be suitably used from the viewpoint of curability and storage stability.

[0055] The epoxy group-containing silane coupling agent (B) can be used alone or in combination of two or more types.

[0056] In the coating composition of the present invention, the equivalent ratio of epoxy groups in the epoxy group-containing silane coupling agent (B) to carboxyl groups in the vinyl polycarboxylic acid resin (A) is preferably in the range of 0.5 to 2.0, particularly 0.7 to 1.8, and even more particularly 1.0 to 1.5, in terms of epoxy group / carboxyl group value, from the viewpoint of the chemical resistance (alkali resistance) and boiling water resistance of the resulting coating film.

[0057] <Hydrolyzable silyl group-containing silicone resin (C)> In the present invention, the hydrolyzable silyl group-containing silicone resin (C) is a resin that contains hydrolyzable silyl groups and has a polysiloxane skeleton.

[0058] In this specification, a hydrolyzable silyl group is a group that generates a silanol group by hydrolysis, and that silanol group undergoes dehydration condensation to form a siloxane bond. It is not particularly limited as long as it is a silyl group having both or one of a monovalent hydrolyzable atom (an atom that generates a silanol group by reacting with water) directly bonded to a silicon atom and a monovalent hydrolyzable group (a group that generates a silanol group by reacting with water) directly bonded to a silicon atom. Specific examples of the hydrolyzable silyl group include, for example, halogenated silyl groups such as chlorosilyl and bromosilyl groups, alkoxysilyl groups such as methoxysilyl, ethoxysilyl, propoxysilyl, and butoxysilyl groups, and any combination thereof.

[0059] A hydrolyzable silyl group-containing silicone resin (C) is, for example, the following formula (1): SiX n Y 4-n Formula (1) (In the formula, X represents a hydroxyl group or an alkoxy group, Y represents a monovalent hydrocarbon group which may have substituents, and n represents an integer from 1 to 4.) A resin, such as an oligomer, is produced by the chemical bonding of two or more identical or different organosilanes, represented by [the formula shown].

[0060] In the hydrolyzable silyl group-containing silicone resin (C), the organosilane represented by formula (1) can be bonded in a linear or branched chain. Furthermore, it is preferable that the hydrolyzable silyl group-containing silicone resin (C) has hydrocarbon groups that are directly bonded to silicon atoms.

[0061] Examples of organosilanes represented by formula (1) include dimethyldimethoxysilane, dimethyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriacetoxysilane, γ-aminopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, γ-(3,4-epoxycyclohexyl)ethyltriethoxysilane, γ-(meth)acryloxypropyltrimethoxysilane, phenyltrimethoxysilane, phenyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-chloropropyltrimethoxysilane, β-cyano Ethyltriethoxysilane, methyltrimethoxysilane, methyltriethoxysilane, methyltripropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, tetrapropoxysilane, tetrabutoxysilane, dimethyldichlorosilane, diphenyldichlorosilane, methylphenyldimethoxysilane, trimethylmethoxysilane, trimethylethoxysilane, γ-aminopropyltriethoxysilane, 4-aminobutyltriethoxysilane, p-aminophenyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, aminoethylaminomethylphenethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, 2-(3,Examples include 4-epoxycyclohexyl)ethyltrimethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 4-aminobutyltriethoxysilane, N-(6-aminohexyl)aminopropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltrichlorosilane, (p-chloromethyl)phenyltrimethoxysilane, 4-chlorophenyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-methacryloxypropyltriethoxysilane, 3-acryloxypropyltrimethoxysilane, styrylethyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane, vinyltris(2-methoxyethoxy)silane, trifluoropropyltrimethoxysilane, etc., and any combination thereof.

[0062] From the viewpoint of compatibility with vinyl polycarboxylic acid resin (A) and weather resistance of the formed coating film, the hydrolyzable silyl group-containing silicone resin (C) preferably has methyl groups and / or phenyl groups that are directly bonded to silicon atoms.

[0063] Examples of commercially available hydrolyzable silyl group-containing silicone resins (C) include "SR2406", "SR2410", "SR2420", "SR2416", "SR2402", "AY42-161", "DC-3074" and "DC-3037" (all manufactured by Toray Dow Corning Silicone Co., Ltd.), "FZ-3704" and "FZ-3511" (both manufactured by Nippon Unicar Co., Ltd.), "KC-89S", "KR-500", "X-40-9225", "X-40-9246", "X-40-9250", "K Examples include "R-217", "KR-9218", "KR-213", "KR-510", "X-40-9227", "X-40-9247", "X-41-1053", "X-41-1056", "X-41-1805", "X-41-1810", "X-40-2651", "X-40-2308", "X-40-9238", "X-40-2239", "X-40-2327", "KR-400", "X-40-175", and "X-40-9740" (all manufactured by Shin-Etsu Chemical Co., Ltd.).

[0064] <Paint composition> The paint composition of the present invention contains a vinyl polycarboxylic acid resin (A), an epoxy group-containing silane coupling agent (B), and a hydrolyzable silyl group-containing silicone resin (C), and the content ratio of each of these components is as follows: Based on the total amount of solids in component (A), The solid content of component (B) is 5 to 100% by mass, preferably 20 to 60% by mass. The solid content of component (C) is 5 to 150% by mass, preferably 30 to 100% by mass. It is preferable that the range is within the specified range from the viewpoint of the weather resistance of the resulting coating film.

[0065] In this specification, "solid content" refers to the residue remaining after removing volatile components, and the residue may be solid at room temperature or a liquid with fluidity. The solid content mass can be calculated by multiplying the solid content ratio (the ratio of the amount of residual material after drying to the mass before drying) by the sample mass before drying.

[0066] One possible drying method involves heating 3 grams of the sample at 105°C for 3 hours.

[0067] Furthermore, the paint composition of the present invention may contain, as optional components, a curing catalyst (D); a dehydrating agent; other silane coupling agents other than component (B); a pigment (E); a modifying resin other than components (A) and (C), such as fluororesin, alkyd resin, or urethane resin; an organic solvent; a reactive diluent; and paint additives such as adhesion promoters, anti-settling agents, dispersants, wetting agents, ultraviolet absorbers, light stabilizers, antioxidants, surface modifiers, defoamers, surfactants, preservatives, and antifreeze agents.

[0068] <Curing catalyst (D)> In the paint composition of the present invention, it is preferable to include a curing catalyst from the viewpoint of curability and weather resistance of the resulting coating film.

[0069] Examples of curing catalysts include onium salt compounds, tertiary amines, and latent curing catalysts, which are commonly used in esterification reactions between acids and epoxy.

[0070] Specific examples of onium salt compounds include, for example, tetraethylammonium chloride, tetraethylammonium bromide, tetrabutylammonium chloride, tetrabutylammonium bromide, diethyldibutylammonium bromide, dimethyldioleylammonium chloride, dimethylbenzyllaurylammonium chloride, dimethyldicyclohexylammonium bromide, tetraethylphosphonium chloride, tetraethylphosphonium bromide, tetrabutylphosphonium chloride, dimethylbenzyllaurylphosphonium bromide, triethylsulfonium chloride, and the like.

[0071] Of the above, tetraethylammonium chloride, tetraethylammonium bromide, and lauryltrimethylammonium bromide can be suitably used from the viewpoint of curability and storage stability.

[0072] Tertiary amine compounds have the general formula (R 1 R 2 R 3 N)(R 1 , R 2 and R 3 ) is a hydrocarbon group, which may be the same or different. The hydrogen atoms of the hydrocarbon group may be substituted with halogens or hydroxyl groups. The hydrocarbon group includes linear or branched alkyl groups, cycloalkyl groups, aryl groups (phenyl, tolyl, etc.), aralkyl groups (benzyl, etc.), etc. ) is a compound represented by ).

[0073] Specifically, for example, trimethylamine, triethylamine, triisopropylamine, tri-n-propylamine, tri-n-butylamine, N,N-dimethylhexylamine, N,N-dimethyloctylamine, N,N-dimethyldecylamine, N,N-dimethyllaurylamine, N,N-dimethylmyristylamine, N,N-dimethylpalmitylamine, N,N-dimethylstearylamine, N,N-dimethylbehenylamine, N,N-dimethylcocoalkylamine, N,N-dimethyloleylamine, N-methyldihexylamine, N-methyldioctylamine, N-methyl Examples include trialkylamines such as didecylamine, N-methyldicocoalkylamine, and N-methyldioleylamine; trialkanolamines such as trimethanelamine and triethanolamine; N,N-dialkylalkanolamines such as N,N-dimethylethanolamine and N,N-diethylethanolamine; N-alkyldialkanolamines such as N-methyldiethanolamine and N-ethyldiethanolamine; and N-alkylmorpholines such as N-methylmorpholine and N-ethylmorpholine. These can be used individually or in combination of two or more.

[0074] As a catalyst for the paint composition of the present invention, from the viewpoint of improving the storability of the paint, it is preferable to use a latent curing catalyst composed of (a) an onium salt compound or a tertiary amine and (b) an acidic phosphate ester. In the latent curing catalyst, components (a) and (b) may be either a mixture or reactants.

[0075] As the onium salt compound, the above-mentioned onium salt compound can be used.

[0076] From the viewpoint of suppressing a decrease in electrostatic coating suitability due to a decrease in the electrical resistance of the paint composition, it is preferable to use a tertiary amine as component (a).

[0077] As the tertiary amine compound, the tertiary amine compounds described above can be used.

[0078] (b) Acidic phosphate esters are organic acidic (or phosphate) esters obtained by substituting some of the hydrogen atoms of an inorganic phosphorus compound, such as phosphoric acid, phosphorous acid, or a condensate thereof, with an alkyl group or aryl group. The alkyl group may be of the linear or branched type, and examples of such groups include methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, n-pentyl, n-hexyl, n-heptyl, 2-ethylhexyl, and n-decyl.

[0079] Specifically, examples include dimethyl phosphate, diethyl phosphate, dipropyl phosphate, monobutyl phosphate, dibutyl phosphate, mono-2-ethylhexyl phosphate, bis(ethylhexyl) phosphate, monophenyl phosphate, diphenyl phosphate, and mono-2-ethylhexyl phosphite.

[0080] Among these, diphenyl phosphate can be cited as a particularly preferred option.

[0081] The blending ratio of component (a) and component (b) described above is preferably within the range of about 2 to 90% by mass, more preferably about 25 to 75% by mass for component (a), and preferably about 10 to 98% by mass, more preferably about 25 to 75% by mass for component (b), based on the total amount of both components. If the blending ratio of component (a) is less than about 2% by mass, the low-temperature curability of the paint composition may decrease, while if the blending ratio of component (a) exceeds about 90% by mass, the storage stability of the paint composition may decrease.

[0082] In latent curing catalysts, preferred combinations of component (a) and component (b) include an onium salt compound or a combination of a methyldialkyl tertiary amine or dimethylalkyl tertiary amine having 8 to 24 carbon atoms in the alkyl group, and diphenyl phosphate or bis(2-ethylhexyl) phosphate.

[0083] When a curing catalyst (D) is included, from the viewpoint of curability and storage stability, the amount of curing catalyst (D) is preferably in the range of 0.1 to 10% by mass, particularly 0.5 to 5% by mass, and even more particularly 1 to 3% by mass, relative to the total solid content of the vinyl polycarboxylic acid resin (A) and the epoxy group-containing silane coupling agent (B).

[0084] The aforementioned dehydrating agent is used to suppress the deterioration of paint caused by moisture present in the paint or air, and specific examples include trimethyl orthoacetate.

[0085] Other silane coupling agents besides component (B) include, for example, amino group-containing silane coupling agents such as γ-(2-aminoethyl)aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β(aminoethyl)γ-aminopropyltrimethoxysilane, and N-β(aminoethyl)γ-aminopropylmethyldimethoxysilane; mercapto group-containing silane coupling agents such as γ-mercaptopropyltrimethoxysilane; vinyl group-containing silane coupling agents such as vinyltriethoxysilane, vinyltrimethoxysilane, and vinyltris(methoxyethoxy)silane; and (meth)acryloyl group-containing silane coupling agents such as γ-(meth)acryloyloxypropyltrimethoxysilane, γ-(meth)acryloyloxypropyltriethoxysilane, and γ-(meth)acryloyloxypropyldimethoxymethylsilane.

[0086] Examples of the aforementioned pigment (E) include coloring pigments such as titanium dioxide, carbon black, lead yellow, ochre, yellow iron oxide, Hansa yellow, pigment yellow, chrome orange, chrome vermilion, permanent orange, amber, permanent red, brilliant carmine, fast violet, methyl violet lake, ultramarine, Prussian blue, cobalt blue, phthalocyanine blue, pigment green, naphthol green, and aluminum paste; extender pigments such as talc, silica, calcium carbonate, mica, kaolin, barium sulfate, and zinc oxide; and rust-preventive pigments. These can be used individually or in combination of two or more.

[0087] In particular, when titanium dioxide is used as a coloring pigment, titanium dioxide surface-treated with silica, alumina, zirconia, selenium, organic components (polyols, etc.) is preferable from the viewpoint of weather resistance of the coating film. The amount of surface treatment is preferably such that the titanium dioxide content is in the range of 83 to 95% by mass. Examples of commercially available surface-treated titanium dioxide include "Typake PFC105" and "Typake CR95" (both product names, manufactured by Ishihara Sangyo Co., Ltd.), "D918" (product name, manufactured by Sakai Chemical Co., Ltd.), "TITANIX WP0038" and "TITANIX JR805" (both product names, manufactured by Teika Co., Ltd.), "Ti-Pure R960" and "Ti-Select TS-6200" (both product names, manufactured by DuPont).

[0088] The amount of pigment can be adjusted as appropriate depending on the type of pigment, but generally, it is preferable that it be within the range of 1 to 200% by mass, and particularly 5 to 150% by mass, based on the total solid content of components (A), (B), and (C).

[0089] Known UV absorbers can be used, such as benzotriazole-based absorbers, triazine-based absorbers, salicylic acid derivative-based absorbers, and benzophenone-based absorbers. By incorporating a UV absorber, the weather resistance of the coating film can be improved.

[0090] The amount of ultraviolet absorber in the paint composition is usually preferably about 0 to 10% by mass, particularly about 0.2 to 5% by mass, and even more preferably about 0.3 to 2% by mass, relative to the total amount of resin solids.

[0091] Conventional light stabilizers can be used, such as hindered amine-based light stabilizers. By incorporating a light stabilizer, the weather resistance and resistance to yellowing of the coating film can be improved.

[0092] The amount of light stabilizer in the paint composition is usually preferably about 0 to 10% by mass, particularly about 0.2 to 5% by mass, and even more preferably about 0.3 to 2% by mass, relative to the total amount of resin solids.

[0093] The paint composition of the present invention can be manufactured by mixing components A, B, and C, as well as other optional components as needed, using a mixing device such as a disperser or homogenizer.

[0094] The coating of the paint composition of the present invention can be applied by coating methods such as dipping, brush coating, roll brush coating, spray coating, roll coating, spin coating, dip coating, bar coating, flow coating, electrostatic coating, airless coating, electrodeposition coating, and die coating.

[0095] The coating film thickness of the coating composition of the present invention can be arbitrarily set depending on the object to be coated and the required coating performance, but it is generally preferable to set it within the range of 10 to 100 μm, and particularly within the range of 20 to 60 μm.

[0096] The coating film of the coating composition of the present invention can usually be cured by heating at a temperature in the range of 100 to 200°C, particularly 130 to 180°C, for 5 to 40 minutes, particularly 10 to 30 minutes.

[0097] The substrate to which the coating composition of the present invention is applied is not particularly limited, and may include, optionally, surface-treated metal materials such as cold-rolled steel sheets, mill scale steel sheets, alloyed galvanized steel sheets, electro-galvanized steel sheets, etc., galvanized steel, stainless steel, aluminum, etc., alkaline substrates such as concrete, mortar, slate, slate tiles, etc., ceramic building materials, plastics, etc.

[0098] The paint composition of the present invention is not particularly limited in its uses, but it is especially suitable for use as a topcoat paint for exterior building materials such as building exteriors, civil engineering and construction materials, vehicle and aircraft materials, and particularly for exterior building materials.

[0099] The above-mentioned objects to be coated may, if necessary, undergo shot blasting, surface preparation, surface treatment, or even primer coating.

[0100] Examples of the above-mentioned primer coatings include water-based or solvent-based primer coatings known in the art.

[0101] Specific examples of the above-mentioned primer coatings include epoxy resin coatings, modified epoxy resin coatings, epoxy resin-based glass flake coatings, epoxy resin coating materials, phthalic acid resin coatings, epoxy ester resin coatings, and the like.

[0102] The paint composition of the present invention is a non-fluororesin-based, one-component curing paint composition that has excellent coating performance such as weather resistance, coating hardness, and chemical resistance, as well as excellent handling properties. Therefore, it can be used particularly suitably as a topcoat paint that complies with PFAS regulations for the above-mentioned applications of the substrate. [Examples]

[0103] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited thereto. In each example, "parts" refers to parts by mass, and "%" refers to mass percent.

[0104] <Manufacturing of paint compositions> Example 1: Production of paint composition No. 1 A paint composition No. 1 with a solid content of 60% by mass was obtained by mixing and stirring 42.5 parts (solids) of vinyl polycarboxylic acid resin (A-1), 17.5 parts (solids) of epoxy group-containing silane coupling agent (B-1), 40 parts (solids) of hydrolyzable silyl group-containing silicone resin (C-1), 90 parts (solids) of PFC-105 (Note 1) (titanium dioxide, manufactured by Ishihara Sangyo Co., Ltd.), 1.1 parts (solids) of DTAB (Note 2), 1.1 parts (solids) of Nacure4054 (Note 3), 1.5 parts (solids) of Ti400 (Note 5), and 1 part (solids) of Ti123 (Note 6). The solid content concentration was adjusted with a solvent.

[0105] In the above, the titanium dioxide pigment was added and mixed as a pigment dispersion paste prepared using 20 parts (solid content) of vinyl polycarboxylic acid resin (A-1).

[0106] Examples 2-22 and Comparative Examples 1-6: Manufacture of paint compositions No. 2-28 Paint compositions No. 2 to 28, each with a solid content of 60% by mass, were obtained in the same manner as in Example 1, except for the formulations shown in Table 1.

[0107] Note that the ingredient proportions (numerical values) in Table 1 represent the solid content mass.

[0108] [Table 1]

[0109] [Table 2]

[0110] [Table 3]

[0111] Furthermore, the ingredients listed in the table are as follows:

[0112] Vinyl polycarboxylic acid resin (A-1): Butyl acetate solution of copolymer of isobutyl methacrylate / 2-ethylhexyl acrylate / ethyl acrylate / methyl methacrylate / hydroxyethyl methacrylate / hydroxyethyl acrylate = 73.3 / 3.7 / 11 / 10 / 0.1 / 1.9, acid value 65, weight-average molecular weight 16000, glass transition temperature 45℃, SP value 8.76, solids content 60%. Vinyl polycarboxylic acid resin (A-2): Styrene / butyl acrylate / butyl methacrylate / maleic anhydride copolymer = 31 / 11 / 46 / 12, butyl acetate solution, acid value 64, weight-average molecular weight 10000, glass transition temperature 30°C, SP value 9.83, solids content 55%.

[0113] Vinyl polycarboxylic acid resin (A-3): Butyl acetate solution of copolymer of isobutyl methacrylate / 2-ethylhexyl acrylate / methyl methacrylate = 73.3 / 16.7 / 10, acid value 65, weight-average molecular weight 16000, glass transition temperature 33°C, SP value 8.60, solids content 60%.

[0114] Vinyl polycarboxylic acid resin (A-4): Butyl acetate solution of copolymer of isobutyl methacrylate / tert-butyl methacrylate / 2-ethylhexyl acrylate / methyl methacrylate = 58.3 / 20 / 16.7 / 5, acid value 33, weight-average molecular weight 16000, glass transition temperature 37°C, SP value 8.33, solids content 60%.

[0115] Vinyl polycarboxylic acid resin (A-5): Diethylene glycol monobutyl ether solution of styrene / ethyl acrylate / methyl methacrylate copolymer = 10 / 55 / 30, acid value 195, weight-average molecular weight 12000, glass transition temperature 36°C, SP value 10.2, solids content 35%.

[0116] Vinyl polycarboxylic acid resin (A-6): Butyl acetate solution of styrene / 2-ethylhexyl acrylate / methyl methacrylate copolymer = 10 / 80 / 10, acid value 65, weight-average molecular weight 16000, glass transition temperature -46℃, SP value 8.54, solids content 60%.

[0117] Vinyl polycarboxylic acid resin (A-7): styrene / tertiary butyl methacrylate / methyl methacrylate copolymer = 40 / 50 / 10, butyl acetate solution, acid value 65, weight-average molecular weight 16000, glass transition temperature 119°C, SP value 9.08, solids content 60%.

[0118] Epoxy group-containing silane coupling agent (B-1): "KBM-403", trade name, manufactured by Shin-Etsu Chemical Co., Ltd., γ-glycidoxypropyltrimethoxysilane, epoxy equivalent 236.

[0119] Epoxy group-containing silane coupling agent (B-2): "MP-200", trade name, manufactured by Momentive, condensate of γ-glycidoxypropyltrimethoxysilane, epoxy equivalent 205.

[0120] Epoxy resin (B-3): "JER-828", product name, manufactured by Mitsubishi Chemical Corporation, bisphenol A type liquid epoxy resin, epoxy equivalent 188.

[0121] Hydrolyzable silyl group-containing silicone resin (C-1): "KR500": Product name, manufactured by Shin-Etsu Chemical Co., Ltd., a methyl group-containing alkoxysilyl group-containing silicone resin. Alkoxysilyl group content: 28%.

[0122] Hydrolyzable silyl group-containing silicone resin (C-2): "CF-2403": Product name, manufactured by Toray Dow Coatings Co., Ltd., a methyl group-containing alkoxysilyl group-containing silicone resin. Alkoxysilyl group content: 36%.

[0123] Hydrolyzable silyl group-containing silicone resin (C-3): "XR31-B1410": Trade name, manufactured by Momentive, a methyl group-containing alkoxysilyl group-containing silicone resin. Alkoxysilyl group content: 14%.

[0124] Hydrolyzable silyl group-containing silicone resin (C-4): "DC-3074": Trade name, manufactured by Toray Dow Coatings Co., Ltd., an alkoxysilyl group-containing silicone resin containing methyl groups that directly bond to silicon atoms and phenyl groups that directly bond to silicon atoms. Alkoxysilyl group content: 16%.

[0125] Silicone resin (C-5): "KF-96": Product name, manufactured by Shin-Etsu Chemical Co., Ltd., dimethyl silicone resin. Contains no alkoxysilyl groups.

[0126] (Note 1) PFC105: "Typake PFC105", titanium dioxide, trade name, manufactured by Ishihara Sangyo Co., Ltd., Al, Si, Zr organic treated titanium dioxide, titanium dioxide content 87%.

[0127] (Note 2) DTAB: Lauryltrimethylammonium bromide (Note 3) Nacure4054: Trade name, manufactured by King Industries, Alkyl phosphate ester, phosphoric acid (2-ethylhexyl), monoester 55 mol%, diester (bis(2-ethylhexyl) phosphate) 39 mol%, phosphoric acid 6%.

[0128] (Note 4) Ti400: UV absorber, TINUVIN400, trade name, manufactured by BASF.

[0129] (Note 5) Ti123: Light stabilizer, TINUVIN123, trade name, manufactured by BASF.

[0130] The test panels were prepared and their performance evaluated according to the following procedure, and the results obtained from the tests are shown in Table 1.

[0131] <Preparing the test board> Each of the paint compositions No. 1 to 28 was applied to an aluminum plate A-1050P (0.8 x 150 x 150 mm, degreased with acetone) treated with chromium phosphate by air spray painting (pressure 0.4 MPa) to a dry film thickness of 40 μm. After setting at 20°C for 10 minutes, the plates were heated and dried in an electric hot air dryer at 160°C for 20 minutes, and then cured at 20°C for 72 hours to obtain each test plate for each paint composition No. 1 to 28.

[0132] <Performance Evaluation> Each paint composition No. 1 to 28 and the test boards for each paint composition were subjected to performance tests according to the following test items, and their performance was evaluated according to the following evaluation criteria. The performance evaluation results are shown in Table 1.

[0133] In the performance evaluation below, ◎ and ○ indicate a passing level, while △ and × indicate a failing level.

[0134] Storage stability: The liquid state after storage in a constant temperature room at 40°C for 30 days was evaluated according to the following criteria. ◎: No increase in liquid viscosity. ○: A slight increase in the viscosity of the liquid is observed. △: Increased viscosity of the liquid is observed. ×: The liquid will gel. Weather resistance: Accelerated weathering resistance was evaluated using a xenon weather meter. The gloss of the test panel coating after 5000 hours was compared with the gloss of the initial test panel coating that had not undergone accelerated weathering testing, according to the following criteria. ◎: The gloss hardly decreased at all. ○: The gloss has decreased slightly, but there are no practical problems. △: Glossiness has slightly decreased. ×: The gloss has significantly decreased.

[0135] Pencil Hardness: In accordance with JIS K 5600-5-4, a pencil lead was applied to the test coated plate surface at an angle of approximately 45°, and while pressing firmly enough to prevent the lead from breaking, it was moved forward at a uniform speed for approximately 10 mm. The hardness symbol of the hardest pencil that did not break the coating was defined as the pencil hardness. ◎: 2H or more. ○:H. △: F or HB. ×: B or less.

[0136] Finished appearance: The appearance of the painted surface of each test panel was evaluated visually and by gloss value. ◎: Excellent smoothness and a 60-degree gloss value of 70 or higher. ○: Good smoothness and a 60-degree gloss value of 60 or higher and less than 70. ×: Significant deterioration in at least one of the following finish appearances: underarms, undulation, dullness, or rough skin, or a 60-degree gloss value of less than 60.

[0137] Impact resistance: In accordance with JIS K-56005-3:1999, Part 5: Mechanical properties of coatings, Section 3: Resistance to falling weights, a DuPont impact tester was used at room temperature of 20°C. The test was conducted on the surface coating of each test plate under the following conditions: a weight of 500g, a weight height of 50cm, and a tip diameter of 1 / 2 inch on the impact point. Cellophane adhesive tape was then applied to the surface of the coating and rapidly removed. The degree of cracking and peeling of the coating was then evaluated. ◎: No cracking or peeling of the paint film was observed. ○: Cracks were observed in the paint film, but no peeling was observed. △: Cracks were observed in the paint film, and peeling occurred. ×: Many cracks and significant peeling are observed in the paint film.

[0138] Acid resistance: The appearance of the coating film after immersing the coated board in a 5% sulfuric acid aqueous solution at 23°C for 72 hours was compared with the gloss of the initial board. ◎: The gloss hardly decreased. ○: The gloss has decreased slightly, but this does not affect its practical use. △: The gloss has decreased and it is not at a usable level. ×: The gloss has significantly decreased.

[0139] Alkali resistance: The appearance of the coating film after immersing the coated board in a 5% sodium carbonate solution at 40°C for 144 hours was compared with the gloss of the initial board. ◎: The gloss hardly decreased. ○: The gloss has decreased slightly, but this does not affect its practical use. △: The gloss has decreased and it is not at a usable level. ×: The gloss has significantly decreased.

[0140] Boiling water resistance: The appearance of the coating film after immersing the coated board in deionized water at 99°C for 7 hours was compared with the gloss of the initial board. ◎: The gloss hardly decreased. ○: The gloss has decreased slightly, but this does not affect its practical use. △: The gloss has decreased and it is not at a usable level. ×: The gloss has significantly decreased. [Industrial applicability]

[0141] This invention provides a one-component curing paint composition that exhibits excellent coating performance, including weather resistance, coating hardness, chemical resistance, and impact resistance, and is compliant with fluororesin regulations such as PFAS regulations.

Claims

1. A one-component curable coating composition containing a vinyl polycarboxylic acid resin (A) having a glass transition temperature of 0°C to 100°C, an epoxy group-containing silane coupling agent (B), and a hydrolyzable silyl group-containing silicone resin (C).

2. The one-component curable coating composition according to claim 1, wherein the solubility parameter of the vinyl polycarboxylic acid resin (A) is in the range of 7 to 10.

3. The one-component curing paint composition according to claim 1 or 2, further containing a curing catalyst (D).

4. A one-component curable paint composition according to any one of claims 1 to 3, further containing a pigment (E).

5. A painting method comprising applying a one-component curing paint composition according to any one of claims 1 to 4 to an object to be painted.

6. An exterior building material coated with the one-component curing paint composition according to any one of claims 1 to 4.

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