Water-based covering materials

Abstract

To provide an aqueous coating material which is excellent in weather resistance, water resistance and stain resistance.SOLUTION: An aqueous coating material contains synthetic resin emulsion obtained from a monomer group containing a carboxyl group-containing monomer, a crosslinking agent containing a carbodiimide group-containing compound, an ultraviolet absorber containing oxalic anilide or its derivative, and coloring particles having a particle diameter of 0.05 to 10 mm.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to an aqueous coating material excellent in weather resistance, water resistance and stain resistance. Background Art

[0002] Buildings and civil engineering structures are usually subjected to surface finishing with a coating material, which not only protects the frame from wind, rain, direct sunlight and the like, but also plays a role in maintaining aesthetic appearance. In recent years, as a surface finish, there have been an increasing number of cases where a decorative finish having the aesthetic appearance, texture, luxury feeling, solid feeling and the like unique to natural stone is desired. As such a decorative finish, for example, it is possible to provide a decorative finish with a coating material in which colored particles are blended together with a binder. Such a coating material is required to have weather resistance, water resistance and stain resistance against wind, rain, direct sunlight and the like. On the other hand, in recent years, in consideration of non-pollution and safety, aqueous coating materials using a synthetic resin emulsion as a binder have been increasingly used.

[0003] As one of the methods for improving weather resistance, a method of introducing an ultraviolet absorber, a light stabilizer or the like into a coating material is considered effective. For example, Patent Document 1 describes that weather resistance is improved by using a benzotriazole-based ultraviolet absorber. Prior Art Literature Patent Literature

[0004] Patent Document 1 Japanese Unexamined Patent Publication No. 2020-158578 Summary of the Invention Problems to be Solved by the Invention

[0005] However, in Patent Document 1, stain resistance may be inferior, and it may be difficult to maintain aesthetic appearance. Means for Solving the Problems

[0006] This invention was completed after diligent research to achieve excellent weather resistance, water resistance, and stain resistance. The results showed that by using anilide oxalate or its derivative as an ultraviolet absorber, a synthetic resin emulsion containing a carboxyl group monomer as the synthetic resin emulsion, and a carbodiimide group-containing compound as the crosslinking agent, excellent weather resistance, water resistance, and stain resistance can be achieved.

[0007] In other words, the present invention has the following features. 1. An aqueous coating material containing a synthetic resin emulsion, a crosslinking agent, an ultraviolet absorber, and colored particles with a particle size of 0.05 to 10 mm, The synthetic resin emulsion is obtained from a group of monomers including a carboxyl group-containing monomer. The crosslinking agent contains a carbodiimide group-containing compound, The UV absorber contains anilide oxalate or a derivative thereof. fruit, The oxalic acid anilide or its derivative is a compound represented by the following formula (1): Formula (1) TIFF0007927027000001.tif2880 (R may be the same or different, and represents a hydrogen atom, an alkyl group having 1 to 24 carbon atoms, an alkoxy group, or an alkylthio group.) A water-based coating material characterized by the following features. 2. The aqueous coating material according to 1, characterized in that the amount of carboxyl group-containing monomers contained in the synthetic resin emulsion is 0.1% by mass or more and 20% by mass or less of the total amount of monomers. 3. The aqueous coating material according to 1, characterized in that it contains 0.1 parts by mass or more and 10 parts by mass or less of the oxalic acid anilide or its derivative per 100 parts by mass of the solid content of the synthetic resin emulsion. 4. The aqueous coating material according to claim 1, characterized in that the synthetic resin emulsion is obtained from a group of monomers including a cycloalkyl group monomer. 5. The aqueous coating material according to 4., characterized in that the content of cycloalkyl group-containing monomers in the synthetic resin emulsion is 5% by mass or more and 80% by mass or less of the total amount of monomers. [Effects of the Invention]

[0008] The aqueous coating material of the present invention has excellent weather resistance, water resistance, and stain resistance. [Modes for carrying out the invention]

[0009] The following describes embodiments for carrying out the present invention.

[0010] The present invention relates to an aqueous coating material containing a synthetic resin emulsion, a crosslinking agent, an ultraviolet absorber, and colored particles with a particle size of 0.05 to 10 mm, wherein the synthetic resin emulsion is obtained from a group of monomers including a carboxyl group-containing monomer, the crosslinking agent contains a carbodiimide group-containing compound, and the ultraviolet absorber contains oxalic acid anilide or a derivative thereof. This invention has discovered that when oxalic acid anilide or its derivatives are immobilized by being embedded in the crosslinked structure of a synthetic resin emulsion containing a carboxyl group monomer and a carbodiimide group containing a compound, excellent weather resistance, water resistance, and stain resistance can be exhibited.

[0011] The oxalic acid anilide or its derivative used in the present invention is a compound represented by the following formula (1). Formula (1) TIFF0007927027000002.tif2880 (R may be the same or different, and represents a hydrogen atom, an alkyl group having 1 to 24 carbon atoms, an alkoxy group, or an alkylthio group.)

[0012] Oxanilide or a derivative thereof specifically includes 2-methyl-2'-ethoxyoxalanilide, 2-ethyl-2'-ethoxyoxalanilide, 4,4'-dimethoxyoxalanilide, 4,4'-dioctyloxyoxalanilide, 2,2'-diethoxyoxalanilide, 2,2'-dioctyloxy-5,5'-di-tert-butoxalanilide, 2,2'-didodecyloxy-5,5'-di-tert-butoxalanilide, N,N'-bis(3-dimethylaminopropyl)oxalamide, a mixture of 2-ethoxy-5-tert-butyl-2'-ethoxalanilide and 2-ethoxy-2'-ethyl-5,4'-di-tert-butoxalanilide thereof, a mixture of o- and p-methoxy-disubstituted oxalanilides, a mixture of o- and p-ethoxy-disubstituted oxalanilides, and the like, and one or more of these may be used in combination. In the present invention, it is particularly preferable to use 2-ethyl-2'-ethoxyoxalanilide.

[0013] In addition, in the present invention, other than the above oxanilide or derivative thereof, ultraviolet absorbers such as benzophenone-based, benzotriazole-based, and triazine-based ultraviolet absorbers, and light stabilizers such as hindered amine-based light stabilizers may also be mixed to an extent that does not impair the effects of the present invention.

[0014] The synthetic resin emulsion used in the present invention is obtained from a monomer group containing a carboxyl group-containing monomer.

[0015] Examples of the carboxyl group-containing monomer include (meth)acrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid, isocrotonic acid, salicylic acid, cinnamic acid, and the like, and one or more of these may be used.

[0016] In addition, in the present invention, a synthetic resin emulsion can be obtained by mixing other monomers in addition to the carboxyl group-containing monomer. As other monomers, for example, Monomers having a cycloalkyl group such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclooctyl (meth)acrylate, cyclododecyl (meth)acrylate, 4-tert-butylcyclohexyl (meth)acrylate, etc. Hydroxyl group-containing monomers such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, 2-hydroxybutyl (meth)acrylate, 2-hydroxypentyl (meth)acrylate, 4-hydroxypentyl (meth)acrylate, 1-methyl-4-hydroxypentyl (meth)acrylate, 3-ethyl-3-hydroxyhexyl (meth)acrylate, 2-hydroxydecyl (meth)acrylate, 3-hydroxypropyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 1-methyl-4-hydroxybutyl (meth)acrylate, 5-hydroxypentyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 7-hydroxyheptyl (meth)acrylate, 8-hydroxyoctyl (meth)acrylate, 2-methyl-8-hydroxyoctyl (meth)acrylate, 7-methyl-8-hydroxyoctyl (meth)acrylate, 9-hydroxynonyl (meth)acrylate, 10-hydroxydecyl (meth)acrylate, hydroxymethylcyclohexyl (meth)acrylate, etc., Alkoxysilyl group-containing monomers such as 3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane, etc., (meth)acrylamide, ethyl(meth)acrylamide, N-ethyl(meth)acrylamide, N-isopropyl(meth)acrylamide, Nn-propyl(meth)acrylamide, N-cyclopropyl(meth)acrylamide, N-(meth)acroylpyrrolidine, N,N-dimethyl(meth)acrylamide, N,N-diethyl(meth)acrylamide, N-methyl-N-ethyl(meth)acrylamide, N-methyl-N-isopropyl(meth)acrylamide, N-methyl-Nn-propyl(meth)acrylamide, N-methylol(meth)acrylamide, N-[3-(dimethylamino)propyl](meth)acrylamide, vinylamide, N,N-methylenebisacrylamide, diacetone(meth)acrylamide, N-methylol(meth)acrylamide, acrylamide glycolic acid, methyl acrylamide glycolate, dimethoxyhydroxyethylacrylamide, and other amide group-containing monomers. Methyl (meth)acrylate, ethyl (meth)acrylate, isopropyl (meth)acrylate, n-propyl (meth)acrylate, i-butyl (meth)acrylate, n-butyl (meth)acrylate, sec-butyl (meth)acrylate, isobutyl (meth)acrylate, t-butyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, n-hexyl (meth)acrylate, octyl (meth)acrylate, lauryl (meth)acrylate, stearyl (meth)acrylate, myristyl (meth)acrylate, palmityl (meth)acrylate, trifluoroethyl (meth)acrylate, n-amyl (meth)acrylate, isoamyl (meth)acrylate, t- Alkyl-containing monomers such as amyl (meth)acrylate, oxyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, dodecenyl (meth)acrylate, octadecyl (meth)acrylate, phenyl (meth)acrylate, isobornyl (meth)acrylate, benzyl (meth)acrylate, 2-phenylethyl (meth)acrylate, 2-methoxyethyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, tripropylmethyl (meth)acrylate, triisopropylmethyl (meth)acrylate, tributylmethyl (meth)acrylate, triisobutylmethyl (meth)acrylate, tri-t-butylmethyl (meth)acrylate, etc. Alkylene glycol chain-containing monomers such as (methoxy)polyethylene glycol (meth)acrylate, (methoxy)polypropylene glycol (meth)acrylate, (methoxy)polyethylene glycol-polypropylene glycol (meth)acrylate, (methoxy)polyethylene glycol allyl ether, (methoxy)polypropylene glycol allyl ether, and (methoxy)polyethylene glycol-polypropylene glycol allyl ether. Amino group-containing monomers such as butylvinylbenzylamine, vinylphenylamine, p-aminostyrene, N,N-dimethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, N,N-diethylaminopropyl (meth)acrylate, N-[2-(meth)acryloyloxyethyl]piperidine, N-[2-(meth)acryloyloxyethyl]pyrrolidine, N-[2-(meth)acryloyloxyethyl]morpholine, 4-[N,N-dimethylamino]styrene, 4-[N,N-diethylamino]styrene, 2-vinylpyridine, 4-vinylpyridine, etc. Glycidyl group-containing monomers such as glycidyl (meth)acrylate, diglycidyl fumarate, 3,4-epoxycyclohexyl (meth)acrylate, 3,4-epoxyvinylcyclohexane, allyl glycidyl ether, ε-caprolactone-modified glycidyl (meth)acrylate, and β-methylglycidyl (meth)acrylate. Carbonyl group-containing monomers such as diacetone (meth)acrylate, diacetone (meth)acrylamide, acrolein, vinyl methyl ketone, vinyl ethyl ketone, vinyl (iso)butyl ketone, acetonyl acrylate, acrylic alkylpropanals, methacrylic alkylpropanals, 2-hydroxypropyl acrylate acetyl acetate, tandiol acrylate acetyl acetate, acetoacetoxyethyl (meth)acrylate, and acetoacetoxyaryl esters. Nitrile group-containing monomers such as (meth)acrylonitrile, Monomers containing isocyanate groups such as methacryloyl isocyanates, Oxazoline group-containing monomers such as vinyloxazoline, 2-vinyl-2-oxazoline, and 2-propenyl-2-oxazoline. Hydrazino group-containing monomers such as propylene-1,3-dihydrazine and butylene-1,4-dihydrazine, Acetoacetoxyl group-containing monomers such as acetoacetoxyethyl (meth)acrylate and acetoacetoxyaryl ester, Methylol group-containing monomers such as N-methylol(meth)acrylamide, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloylamino-1,2,2,6,6-pentamethylpiperidine, 4-cyano-4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, 4-(meth)acryloyloxy-1-methylcarbamoyloxy-2,2,6,6-teto Piperidyl group-containing monomers such as methylpiperidine, 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-crotonyloxy-2,2,6,6-tetramethylpiperidine. vinylidene fluoride and other vinylidene halide monomers, Aromatic vinyl monomers such as styrene, 2-methylstyrene, chlorostyrene, vinyltoluene, t-butylstyrene, vinylanisole, and vinylnaphthalene. Sulfonic acid-containing monomers such as styrene sulfonic acid and vinyl sulfonic acid, Benzophenone monomers such as 2-hydroxy-4-(meth)acryloxybenzophenone, 2-hydroxy-5-(meth)acryloxybenzophenone, 2-hydroxy-4-{(meth)acryloxy-ethoxy}benzophenone, 2-hydroxy-4-{(meth)acryloxy-diethoxy}benzophenone, 2-hydroxy-4-{(meth)acryloxy-triethoxy}benzophenone, Benzotriazole monomers such as 2-{2'-hydroxy-5'-(meth)acryloxyethylphenyl}-2H-benzotriazole, 2-{2'-hydroxy-5'-(meth)acryloxyethyl-3-t-butylphenyl}-2H-benzotriazole, and 3-(meth)acryloyl-2-hydroxypropyl-3-{3'-(2''-benzotriazole)-4-hydroxy-5-t-butyl}phenylpropionate. Ethylene, propylene, isoprene, butadiene, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl versatate ester, vinyl ether, vinyl ketone, and other monomers. These are some examples, and one or more of these can be used. In the present invention, it is preferable to use a monomer containing an alkoxysilyl group together with a monomer having a cycloalkyl group, as this can improve stain resistance.

[0017] The polymerization method for the synthetic resin emulsion used in the present invention is not particularly limited, but the above-mentioned monomers and various additives as needed can be mixed and polymerized using commonly known polymerization methods (emulsion polymerization, suspension polymerization, dispersion polymerization, etc.) to produce the synthetic resin emulsion. Polymerization may be carried out in one step, or in two, three or more steps. Furthermore, the manufactured synthetic resin emulsion may be a single-phase structured synthetic resin emulsion, a two-phase structured synthetic resin emulsion having a core phase and a shell phase, a three-phase structured synthetic resin emulsion having a core phase, an intermediate phase and a shell phase, or a multi-phase structured synthetic resin emulsion having a core phase, two or more intermediate phases and a shell phase. For example, two-phase synthetic resin emulsions produced by two-step polymerization and three-phase synthetic resin emulsions produced by three-step polymerization are preferred because they allow for easier design and manufacture of various physical properties (e.g., weather resistance, stain resistance, water resistance, etc.).

[0018] Examples of additives include water, emulsifiers, initiators, solvents, dispersants, emulsification stabilizers, polymerization inhibitors, polymerization inhibitors, buffers, crosslinking agents, pH adjusters, chain transfer agents, catalysts, etc., and the necessary amounts should be added according to the various polymerization methods and purposes.

[0019] The emulsifier used is not particularly limited and can include anionic emulsifiers, cationic emulsifiers, nonionic emulsifiers, amphoteric emulsifiers, reactive emulsifiers, etc. For example, alkyl sulfonates such as sodium dodecylbenzenesulfonate and sodium dodecylsulfonate, alkyl sulfates such as sodium dodecylbenzenesulfate and sodium dodecyl sulfate, fatty acid salts such as ammonium laurate and sodium stearate, rosinates, alkyl sulfosuccinates, dialkyl sulfosuccinates, α-olefin sulfonates, alkylnaphthalene sulfonates, polyoxyalkylene alkyl (aryl) sulfate salts, polyoxyalkylene alkyl (aryl) sulfonate salts, and other anionic emulsifiers. Quaternary ammonium salts such as lauryltrialkylammonium salt, stearyltrialkylammonium salt, and trialkylbenzylammonium salt, primary to tertiary amine salts, cationic surfactants such as laurylpyridinium salt, benzalkonium salt, benzethonium salt, and laurylamine acetate, Nonionic surfactants such as polyoxyalkylene alkyl ethers, polyoxyalkylene alkylphenyl ethers, polyalkylene glycols, polyoxyalkylene alkyl esters, polyoxyalkylene sorbitan alkyl esters, and sorbitan alkyl esters. Amphoteric surfactants such as carboxybetaine type, sulfobetaine type, aminocarboxylic acid type, and imidazoline derivative type, Also, polyoxyalkylene alkenyl ether sulfate, polyoxyalkylene alkenyl ether, polyoxyalkylene allyl alkyl ether sulfate, polyoxyalkylene allyl alkyl ether, polyoxyalkylene alkyl allyl alkyl ether sulfate, polyoxyalkylene alkyl allyl alkyl ether, polyoxyalkylene alkyl allyl phenyl ether sulfate, polyoxyalkylene alkyl allyl phenyl ether, polyoxyalkylene propenyl alkyl ether sulfate, polyoxyalkylene propenyl alkyl ether, polyoxyalkylene alkyl propenyl alkyl ether sulfate, polyoxyalkylene alkyl propenyl phenyl ether sulfate, polyoxyalkylene alkyl propenyl phenyl ether, polyoxyalkylene allyl oxyalkyl alkoxyalkyl ether sulfate, polyoxyalkylene allyl oxyalkyl alkoxy alkyl ether, polyoxyalkylene allyl oxyalkyl ether sulfate Reactive emulsifiers such as teres, polyoxyalkylene allyloxyalkyl ethers, polyoxyalkylene styrene styrene propenylphenyl ether sulfates, polyoxyalkylene styrene styrene propenylphenyl ethers, alkylallyl sulfosuccinates, alkylpropenyl sulfosuccinates, (meth)acrylic acid polyoxyalkylene sulfonates, specifically, Eleminol JS-20 (manufactured by Sanyo Chemical Industries, Ltd.), Eleminol RS-30 (manufactured by Sanyo Chemical Industries, Ltd.), Aqualon KH-05 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon KH-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon AR-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon AR-20 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon AR-30 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon BC-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon BC-20 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon BC-3025 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adekaria Soap SR-10 (manufactured by ADEKA Corporation), Adekaria Soap SR-20 (manufactured by ADEKA Corporation), Adekaria Soap SR-3025 (manufactured by ADEKA Corporation),Adekarya Soap SE-10N (manufactured by ADEKA Corporation), Antox MS-60 (manufactured by Nippon Emulsifier Co., Ltd.), Latemul PD-104 (manufactured by Kao Corporation), Latemul PD-105 (manufactured by Kao Corporation), Aqualon KN-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon KN-20 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon KN-30 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon KN-5065 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon AN-10 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon AN-20 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon AN-30 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon AN-5065 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon RN-20 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), A Examples of reactive emulsifiers include Qualon RN-30 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon RN-50 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adekaria Soap ER-10 (manufactured by ADEKA Corporation), Adekaria Soap ER-20 (manufactured by ADEKA Corporation), Adekaria Soap ER-30 (manufactured by ADEKA Corporation), Adekaria Soap ER-40 (manufactured by ADEKA Corporation), Adekaria Soap NE-10 (manufactured by ADEKA Corporation), Adekaria Soap NE-20 (manufactured by ADEKA Corporation), Adekaria Soap NE-30 (manufactured by ADEKA Corporation), Latemul PD-420 (manufactured by Kao Corporation), Latemul PD-430 (manufactured by Kao Corporation), Latemul PD-450 (manufactured by Kao Corporation), and others. In this invention, the use of a reactive emulsifier is particularly preferred in terms of weather resistance, water resistance, and other properties.

[0020] Examples of initiators that can be used include persulfate initiators such as ammonium persulfate, potassium persulfate, and sodium persulfate; azo initiators such as 2,2'-azobisisobutyronitrile, 2,2'-azobis(2,4'-dimethylvaleronitrile), 2,2'-azobis(2-amidinopropane) dihydrochloride, and 2,2'-azobis(2-(2-imidazolin-2-yl)propane) dihydrochloride; peroxide initiators such as dialkyl peroxides such as benzoyl peroxide, lauroyl peroxide, and decanoyl peroxide; peroxyesters such as t-butyl peroxybenzoate; hydroperoxides such as cumene hydroperoxide, paramentane hydroperoxide, and t-butyl hydroperoxide; redox initiators; photopolymerization initiators; and reactive initiators.

[0021] The polymerization temperature is not particularly limited, but it should be between 20°C and 90°C.

[0022] The glass transition temperature of the synthetic resin emulsion is not particularly limited, but is preferably between -10°C and 60°C, and more preferably between 0°C and 50°C. While a low glass transition temperature generally results in poor stain resistance, the present invention makes it possible to obtain excellent stain resistance and even better weather resistance even with a low glass transition temperature. Specifically, the present invention makes it possible to obtain excellent stain resistance, even better weather resistance, and water resistance even when the glass transition temperature is between -10°C and 40°C. Furthermore, when the synthetic resin emulsion is a two-phase structured synthetic resin emulsion having a core phase and a shell phase, or a multi-phase structured synthetic resin emulsion having a core phase, at least one intermediate phase, and a shell phase, it is preferable that the total glass transition temperature of the core phase and the shell phase (and further intermediate phase) is between -10°C and 60°C, and more preferably between 0°C and 50°C. Even if the total glass transition temperature is between -10°C and 40°C, excellent stain resistance and even better weather resistance can be obtained. Furthermore, although not particularly limited, it is preferable that the glass transition temperature of the core phase is greater than 35°C and 120°C or less (preferably 40°C to 110°C, more preferably 45°C to 100°C), the glass transition temperature of the shell phase is greater than -45°C and 10°C or less (preferably -40°C to 5°C, more preferably -35°C to 0°C), and the glass transition temperature of the intermediate phase is greater than -10°C and 45°C or less (preferably -5°C to 35°C, more preferably 0°C to 25°C). In this invention, even when the glass transition temperature of the shell phase is low and the glass transition temperature of the core phase is high, excellent stain resistance, and even better weather resistance can be obtained, as well as excellent adhesion and crack resistance. The glass transition temperature is a value that can be calculated using FOX's formula.

[0023] The average particle size of the synthetic resin emulsion is not particularly limited, but is preferably 50 nm to 1000 nm, and more preferably 60 nm to 400 nm. The average particle size was measured using the dynamic light scattering method. Specifically, it was measured using a dynamic light scattering particle size distribution analyzer (LB-550, Horiba, Ltd.) at a measurement temperature of 25°C.

[0024] The content of monomers having carboxyl groups is preferably 0.1% by mass or more and 20% by mass or less, and more preferably 0.3% by mass or more and 15% by mass or less, relative to the total amount of monomers. By maintaining this range, it is possible to obtain a water-based coating material with excellent weather resistance, water resistance, and stain resistance.

[0025] Furthermore, in the present invention, it is particularly preferable to include a monomer having a cycloalkyl group as the monomer. By using a synthetic resin emulsion containing a monomer having a cycloalkyl group, better weather resistance and stain resistance can be achieved.

[0026] The content of monomers having a cycloalkyl group is preferably 5% by mass or more and 80% by mass or less, and more preferably 10% by mass or more and 70% by mass or less, based on the total amount of monomers. By maintaining this range, it is possible to obtain a water-based coating material with excellent weather resistance and stain resistance. Furthermore, in the case of a two-phase synthetic resin emulsion or a multi-phase synthetic resin emulsion with three or more phases, it is preferable that the amount of the intermediate phase is 5% by mass or more and 80% by mass or more, and more preferably 10% by mass or more and 70% by mass or less, relative to the total amount of monomers in the core phase and shell phase (and further intermediate phase).

[0027] The content of oxalic acid anilide or its derivatives is preferably 0.1 parts by mass or more and 10 parts by mass or less, more preferably 0.5 parts by mass or more and 8 parts by mass or less, and more preferably 1 part by mass or more and 6 parts by mass or less, per 100 parts by mass of solid content of the synthetic resin emulsion. Anilide oxalate or its derivatives can be mixed during the polymerization of synthetic resin emulsions, or added after the polymerization of synthetic resin emulsions. In the present invention, it is particularly preferable to mix the oxalic acid anilide or its derivatives during the polymerization of synthetic resin emulsion. By mixing it during the polymerization of synthetic resin emulsion, an aqueous coating material with even better weather resistance, water resistance, and stain resistance can be obtained. Furthermore, when polymerization is carried out in two, three or more stages, the oxalic acid anilide or its derivatives may be mixed at any stage, but in the present invention, it is particularly preferable to mix it at least in the final stage of polymerization, or to mix it at all stages.

[0028] The crosslinking agent used in the present invention is characterized by containing a carbodiimide group-containing compound. The carbodiimide group-containing compound of the present invention is a compound containing a carbodiimide group (-N=C=N-) or its tautomer, a cyanamide group (NC-NH-). By using such a carbodiimide group-containing compound as a crosslinking agent, it can crosslink with carboxyl groups in a synthetic resin emulsion to form a strong coating film, and incorporate oxalic acid anilide into the crosslinked structure, thereby forming a coating film with excellent weather resistance, water resistance, and stain resistance. Such carbodiimide group-containing compounds can be obtained using diisocyanate compounds as raw materials. Examples of diisocyanate compounds include aliphatic isocyanates such as hexamethylene diisocyanate, 1,4-tetramethylene diisocyanate, 2-methylpentane-1,5-diisocyanate, and lysine diisocyanate; alicyclic diisocyanates such as isophorone diisocyanate, norbornane diisocyanate, hydrogenated tolylene diisocyanate, hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate, and hydrogenated tetramethylxylene diisocyanate; and 2,4'-dicyclohexylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, and 2,4'-diphenylmethane diisocyanate. Examples include aromatic diisocyanates such as annetes, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, p-phenylenediisocyanate, m-phenylenediisocyanate, 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, o-tolidine diisocyanate, naphthylene diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 3,3'-dimethyl-4,4'-diphenyl ether diisocyanate, and 3,3'-dimethyl-4,4'-diphenyl ether diisocyanate, and one or more of these can be used.

[0029] Furthermore, the carbodiimide group-containing compound may be modified in which some or all of the isocyanate groups are modified with a compound having a functional group that can react with the isocyanate group. Functional groups that can react with isocyanate groups include hydroxyl groups, amine groups, carboxyl groups, epoxy groups, and others, and these can be selected and used as appropriate. In the present invention, it is particularly preferable to use glycols such as alkylene glycols and alkylene glycol ethers.

[0030] The content (solids) of the carbodiimide group-containing compound is preferably 0.1 parts by mass or more and 10 parts by mass, and more preferably 0.3 parts by mass or more and 8 parts by mass, per 100 parts by mass of the solids of the synthetic resin emulsion. The carbodiimide group-containing compound can be mixed during the production of the synthetic resin emulsion or added after the production of the synthetic resin emulsion.

[0031] Furthermore, the present invention may also include crosslinking agents other than carbodiimide group-containing compounds. Examples of crosslinking agents other than carbodiimide group-containing compounds include hydrazino group-containing compounds, isocyanate group-containing compounds, amino group-containing compounds, epoxy group-containing compounds, oxazoline group-containing compounds, silanol group-containing compounds, and metal complexes.

[0032] The colored particles used in this invention are for aesthetic purposes and include, for example, colored aggregates and colored gel particles, with a particle diameter of 0.05 mm to 10 mm (preferably 0.06 mm to 8 mm).

[0033] Examples of colored aggregates include crushed marble, granite, serpentinite, fluorite, crimsonite, feldspar, silica, silica sand, crushed ceramics, crushed glass, glass beads, crushed resin, resin beads, metal granules, mica, talc, clay, diatomaceous earth, shell fragments, coral fragments, plant fragments, and wood fragments. Other examples include aggregates whose surfaces are colored and coated with pigments, dyes, glazes, etc.

[0034] The colored gel particles contain, for example, a coloring agent and a synthetic resin. The synthetic resin is not particularly limited to water-dispersible, water-soluble, solvent-dispersible, or solvent-soluble types, such as acrylic resin, urethane resin, epoxy resin / vinyl acetate resin, polyester resin, alkyd resin, vinyl chloride resin, acrylic silicone resin, and fluororesin. The colorants are not particularly limited and include, for example, titanium dioxide, zinc oxide, carbon black, lamp black, bone black, graphite, black iron oxide, copper chromium black, cobalt black, copper manganese iron black, red iron oxide, molybdate orange, permanent red, permanent carmine, anthraquinone red, perylene red, quinacridone red, yellow iron oxide, titanium yellow, first yellow, benzoimidazolone yellow, chrome green, cobalt green, phthalocyanine green, ultramarine, navy blue, cobalt blue, phthalocyanine blue, quinacridone violet, dioxazine violet, heavy calcium carbonate, precipitated calcium carbonate, kaolin, talc, clay, earthenware clay, china clay, barium sulfate, barium carbonate, silica powder, diatomaceous earth, aluminum pigments, pearl pigments, fluorescent pigments, phosphorescent pigments, metallic pigments, etc. Colored gel particles are particles obtained by mixing a coloring agent with such a synthetic resin. In addition to the above, the colored gel particles may also contain crosslinking agents, dispersion stabilizers, gel-forming substances, extender pigments, aggregates, dyes, fibers, thickeners, leveling agents, wetting agents, plasticizers, film-forming aids, antifreeze agents, pH adjusters, preservatives, antifungal agents, antialgal agents, antibacterial agents, defoaming agents, fragrances, light stabilizers, ultraviolet absorbers, photocatalysts, crosslinking agents, flame retardants, solvents, water, etc.

[0035] The amount of such colored particles is preferably 5 parts by mass or more and 2000 parts by mass or less, and more preferably 10 parts by mass or more and 1500 parts by mass or less, per 100 parts by mass of solid content of the synthetic resin emulsion. Furthermore, one or more types of colored particles may be used, and one or more colors may be used in combination. A mixture of colored aggregate and colored gel particles is also acceptable.

[0036] In addition to the components described above, the aqueous coating material of the present invention may also contain various additives within a range that does not impair the effects of the present invention. Examples of such additives include dispersion media such as water and solvents, dispersants, gelling agents, crosslinking agents, pigments, film-forming aids, plasticizers, antifreeze agents, preservatives, antifungal agents, antialgal agents, antibacterial agents, defoaming agents, leveling agents, coupling agents, thickeners, pigment dispersants, anti-settling agents, anti-sagging agents, surface modifiers, wetting agents, pH adjusters, fibers, crosslinking agents, antioxidants, curing catalysts, matting agents, fragrances, light stabilizers, UV absorbers, photocatalysts, flame retardants, and the like.

[0037] Examples of pigments include inorganic coloring pigments such as titanium dioxide, zinc oxide, carbon black, lamp black, bone black, graphite, black iron oxide, cobalt black, copper manganese iron black, ferric oxide (red iron oxide), molybdate orange, yellow iron oxide, titanium yellow, ultramarine, Prussian blue, cobalt blue, cobalt green, iron-chromium complex oxide, manganese-bismuth complex oxide, manganese-yttrium complex oxide, manganese-iron-cobalt complex oxide, azo-based, naphthol-based, pyrazolone-based, and ammonium compounds. Examples include organic coloring pigments such as traquinone, perylene, quinacridone, disazo, isoindolinone, benzimidazole, phthalocyanine, and quinophthalone; functional pigments such as pearl pigments, fluorescent pigments, phosphorescent pigments, and metallic pigments; extender pigments such as heavy calcium carbonate, precipitated calcium carbonate, kaolin, talc, clay, earthenware clay, china clay, barium sulfate, barium carbonate, silica powder, and diatomaceous earth; and pearl pigments, aluminum pigments, metallic pigments, phosphorescent pigments, and fluorescent pigments. These can be used individually or in combination of two or more.

[0038] The aqueous coating material of the present invention can be suitably used as a topcoat, finishing material, protective material, etc., and can be finished by one or more coats. For example, it can be applied to various substrates such as concrete, mortar, siding boards, extruded panels, ALC, gypsum boards, perlite panels, tiles, glass panels, wood panels, plastic panels, and metal panels. Furthermore, these substrates can be applied to those that have undergone some kind of surface treatment (filler treatment, putty treatment, surfacer treatment, sealer treatment, etc.), or to those that have been treated with a primer or intermediate coating, or to existing coatings that have already been formed.

[0039] Various painting methods can be employed, such as brush painting, trowel painting, roller painting, spray painting, and gun painting. The amount of paint applied per coat is preferably 0.03 to 8.0 kg / m². 2 More preferably 0.05 to 6.0 kg / m 2 Furthermore, after the first coat of paint has been applied and the paint film has dried, the next coat (overcoat) can be applied. The drying temperature is preferably -10 to 50°C, more preferably -5 to 40°C. [Examples]

[0040] The following examples illustrate the features of the present invention. However, the present invention is not limited to the examples provided herein.

[0041] (Example 1) Aqueous coating material 1 was obtained by mixing synthetic resin emulsion 1 (50% by mass solids, glass transition temperature 20°C), colored particles 1, colored particles 2, ultraviolet absorber 1 (2-ethyl-2'-ethoxyoxalanilide), crosslinking agent 1 (glycol-modified polycarbodiimide obtained by 4,4'-dicyclohexylmethane diisocyanate), and additives (film-forming aid, defoamer, dispersant) according to the formulation shown in Table 1. The obtained aqueous coating material 1 was subjected to the following weather resistance test, stain resistance test, and water resistance test. The evaluation results are shown in Table 1. Synthetic resin emulsion 1 was prepared by polymerization using methyl methacrylate (75 parts by mass), n-butyl acrylate (85 parts by mass), methacrylic acid (5 parts by mass), and cyclohexyl methacrylate (35 parts by mass) as monomers, and further polymerized by conventional methods using emulsifier 1 (polyoxyethylene alkyl sulfate ammonium salt), initiator (ammonium persulfate), and water. Colored particle 1 is a colored gel particle (particle size 5-6 mm, brown) of a colored paint whose main components are acrylic resin emulsion, black iron oxide, yellow iron oxide, and titanium dioxide. Colored particles 2 are granular gel-like material (particle size approximately 4-5 mm, black) of a colored paint mainly composed of acrylic resin emulsion and black iron oxide.

[0042] (Weather resistance test) A slate board that had been pre-coated with an acrylic resin-based primer (black) was spray-painted with the obtained water-based coating material 1, and after drying for 24 hours, a film with a dry thickness of 0.1 mm was formed, and a test specimen was obtained. The obtained test specimens were subjected to an accelerated weathering test using an iSuper UV tester (manufactured by Iwasaki Electric Co., Ltd.), with each cycle consisting of 6 hours of light irradiation and 2 hours of condensation (total 8 hours). After 80 cycles, the appearance of the coating was checked, and the occurrence of defects (blistering, peeling, cracking, discoloration, etc.) was evaluated. The evaluation was performed on a four-point scale (Excellent: ◎ > ○ > △ > ×: Poor), with "◎" indicating no defects and "×" indicating clear defects.

[0043] (Stain resistance test) A slate board that had been pre-coated with an acrylic resin-based primer (white) was spray-painted with the obtained water-based coating material 1, and after drying for 24 hours, a film with a dry thickness of 0.1 mm was formed, and a test specimen was obtained. The obtained test specimens were placed vertically facing south in Ibaraki City, Osaka Prefecture, and exposed to the outdoors for six months. After six months, the contamination status of the test specimen surfaces was visually evaluated. The evaluation was conducted on a four-point scale (Excellent: ◎ > ○ > △ > ×: Poor), with "◎" indicating no contamination and "×" indicating significant contamination.

[0044] (Water resistance test) A slate board that had been pre-coated with an acrylic resin-based primer (black) was spray-painted with the obtained water-based coating material 1, and after drying for 24 hours, a film with a dry thickness of 0.1 mm was formed, and a test specimen was obtained. The obtained test specimens were immersed in water at 23°C for 24 hours, and the color difference before and after immersion was measured and evaluated using a spectrophotometer. The evaluation was conducted on a four-point scale (Excellent: ◎ > ○ > △ > ×: Poor), with a color difference of less than 5 being marked "◎" and a color difference of 20 or more being marked "×".

[0045] [Table 1]

[0046] (Example 2) Aqueous coating material 2 was obtained using the formulation shown in Table 1, in the same manner as in Example 1. The obtained aqueous coating material 2 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1. Synthetic resin emulsion 2 (solids content 50% by mass, glass transition temperature 28°C) was prepared by using methyl methacrylate (70 parts by mass), 2-ethylhexyl acrylate (65 parts by mass), methacrylic acid (5 parts by mass), and cyclohexyl methacrylate (60 parts by mass) as monomers, adding ultraviolet absorber 1 (2-ethyl-2'-ethoxyoxalanilide) (2 parts by mass), and then polymerizing it using an emulsifier 1, an initiator, and water by a conventional method.

[0047] (Example 3) Aqueous coating material 3 was obtained using the formulation shown in Table 1, in the same manner as in Example 1. The obtained aqueous coating material 3 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1. Synthetic resin emulsion 3 (solids content 50% by mass, glass transition temperature 28°C) was polymerized by a conventional method using methyl methacrylate (30 parts by mass), n-butyl acrylate (10 parts by mass), 2-ethylhexyl acrylate (43 parts by mass), methacrylic acid (2 parts by mass), and cyclohexyl methacrylate (15 parts by mass) as monomers in the first stage, and methyl methacrylate (61 parts by mass), n-butyl acrylate (10 parts by mass), 2-ethylhexyl acrylate (6 parts by mass), methacrylic acid (3 parts by mass), and cyclohexyl methacrylate (20 parts by mass) as monomers in the second stage, and further polymerized using emulsifier 1, initiator, and water. Colored particles 3 are a mixture of white silica sand and gray silica sand (particle size 0.5-0.8 mm). The colored particles 4 are light gray mica (particle size (longest diameter) 0.5-2 mm).

[0048] (Example 4) Aqueous coating material 4 was obtained using the formulation shown in Table 1, in the same manner as in Example 1. The obtained aqueous coating material 4 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1. Synthetic resin emulsion 4 (solids content 50% by mass, glass transition temperature 28°C) was prepared by using methyl methacrylate (24 parts by mass), n-butyl acrylate (10 parts by mass), 2-ethylhexyl acrylate (40 parts by mass), methacrylic acid (2 parts by mass), and cyclohexyl methacrylate (24 parts by mass) as monomers, with UV absorber 1 (1 part by mass) added to this mixture as the first stage. Methyl methacrylate (40 parts by mass), n-butyl acrylate (10 parts by mass), 2-ethylhexyl acrylate (7 parts by mass), methacrylic acid (3 parts by mass), and cyclohexyl methacrylate (40 parts by mass) were used as the second stage, with UV absorber 1 (1 part by mass) added to this mixture. Polymerization was then carried out by a conventional method using emulsifier 1, initiator, and water.

[0049] (Example 5) Aqueous coating material 5 was obtained using the formulation shown in Table 1, in the same manner as in Example 1. The obtained aqueous coating material 5 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1. Synthetic resin emulsion 5 (solids content 50% by mass, glass transition temperature 28°C) was prepared by using methyl methacrylate (6 parts by mass), n-butyl acrylate (5 parts by mass), 2-ethylhexyl acrylate (42 parts by mass), methacrylic acid (2 parts by mass), cyclohexyl methacrylate (35 parts by mass), and cyclohexyl acrylate (10 parts by mass) as monomers, with UV absorber 1 (2 parts by mass) added to this mixture as the first stage. The second stage used methyl methacrylate (6 parts by mass), n-butyl acrylate (5 parts by mass), 2-ethylhexyl acrylate (1 part by mass), methacrylic acid (3 parts by mass), cyclohexyl methacrylate (75 parts by mass), and cyclohexyl acrylate (10 parts by mass), with UV absorber 1 (2 parts by mass) added to this mixture as the second stage. Polymerization was then carried out by a conventional method using emulsifier 1, initiator, and water.

[0050] (Example 6) Aqueous coating material 6 was obtained using the formulation shown in Table 1, in the same manner as in Example 1. The obtained aqueous coating material 6 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1. Synthetic resin emulsion 6 (solids content 50% by mass, glass transition temperature 28°C) was prepared by using methyl methacrylate (24 parts by mass), n-butyl acrylate (10 parts by mass), 2-ethylhexyl acrylate (39 parts by mass), methacrylic acid (2 parts by mass), cyclohexyl methacrylate (24 parts by mass), and γ-methacryloyloxypropyltrimethoxysilane (1 part by mass) as monomers, with UV absorber 1 (1 part by mass) added to this mixture as the first stage. Methyl methacrylate (39 parts by mass), n-butyl acrylate (10 parts by mass), 2-ethylhexyl acrylate (8 parts by mass), methacrylic acid (3 parts by mass), and cyclohexyl methacrylate (40 parts by mass) were used as the second stage, with UV absorber 1 (1 part by mass) added to this mixture. Polymerization was then carried out by a conventional method using emulsifier 1, initiator, and water.

[0051] (Example 7) Aqueous coating material 7 was obtained using the formulation shown in Table 1, in the same manner as in Example 1. The obtained aqueous coating material 7 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1. Synthetic resin emulsion 7 (solids content 50% by mass, glass transition temperature 28°C) was prepared by using methyl methacrylate (24 parts by mass), n-butyl acrylate (10 parts by mass), 2-ethylhexyl acrylate (40 parts by mass), methacrylic acid (2 parts by mass), and cyclohexyl methacrylate (24 parts by mass) as monomers, with UV absorber 1 (1 part by mass) added to this mixture as the first stage. Methyl methacrylate (40 parts by mass), n-butyl acrylate (10 parts by mass), 2-ethylhexyl acrylate (7 parts by mass), methacrylic acid (3 parts by mass), and cyclohexyl methacrylate (40 parts by mass) were used as the second stage, with UV absorber 1 (1 part by mass) added to this mixture as the second stage. Further polymerization was carried out by a conventional method using emulsifier 2 (polyoxyethylene allyloxyalkyl alkoxyalkyl ether sulfate), initiator, and water.

[0052] (Example 8) Aqueous coating material 8 was obtained using the formulation shown in Table 1, in the same manner as in Example 1. The obtained aqueous coating material 8 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1. Synthetic resin emulsion 8 (solids content 50% by mass, glass transition temperature 28°C) was prepared by using methyl methacrylate (29 parts by mass), n-butyl acrylate (1 part by mass), 2-ethylhexyl acrylate (6 parts by mass), methacrylic acid (1 part by mass), and cyclohexyl methacrylate (29 parts by mass) as monomers, to which UV absorber 1 (0.6 parts by mass) was added as the first stage. Methyl methacrylate (14 parts by mass), n-butyl acrylate (9 parts by mass), 2-ethylhexyl acrylate (29 parts by mass), methacrylic acid (2 parts by mass), and cyclohexyl methacrylate (14 parts by mass) were used, to which UV absorber 1 (0.8 parts by mass) was added as the second stage. Polymerization was then carried out by a conventional method using emulsifier 1, initiator, and water.

[0053] (Example 9) Using the formulation shown in Table 1, an aqueous coating material 9 was obtained in the same manner as in Example 1. The obtained aqueous coating material 9 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1. Synthetic resin emulsion 9 (solids content 50% by mass, glass transition temperature 28°C) was polymerized by a conventional method using methyl methacrylate (106 parts by mass), n-butyl acrylate (89 parts by mass), and methacrylic acid (5 parts by mass) as monomers, and further using emulsifier 1, initiator, and water.

[0054] (Example 10) Using the formulation shown in Table 1, an aqueous coating material 10 was obtained in the same manner as in Example 1. The obtained aqueous coating material 10 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1. Synthetic resin emulsion 10 (solids content 50% by mass, glass transition temperature 23°C) uses methyl methacrylate (39 parts by mass), n-butyl acrylate (2 parts by mass), 2-ethylhexyl acrylate (4 parts by mass), methacrylic acid (1 part by mass), and cyclohexyl methacrylate (20 parts by mass) as monomers, to which ultraviolet absorber 1 (0.6 parts by mass) is added as the first stage, methyl methacrylate (19 parts by mass), n-butyl acrylate (8 parts by mass), 2-ethylhexyl acrylate (21 parts by mass), methacrylate The second stage involved using lylic acid (2 parts by mass) and cyclohexyl methacrylate (18 parts by mass), to which ultraviolet absorber 1 (0.8 parts by mass) was added. The third stage involved using methyl methacrylate (10 parts by mass), n-butyl acrylate (19 parts by mass), 2-ethylhexyl acrylate (20 parts by mass), methacrylic acid (2 parts by mass), and cyclohexyl methacrylate (15 parts by mass), to which ultraviolet absorber 1 (0.6 parts by mass) was added. Polymerization was then carried out by a conventional method using emulsifier 1, initiator, and water.

[0055] (Example 11) Using the formulation shown in Table 1, an aqueous coating material 11 was obtained in the same manner as in Example 1. The obtained aqueous coating material 11 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1. Synthetic resin emulsion 11 (50% solids by mass, glass transition temperature 23°C) uses methyl methacrylate (39 parts by mass), n-butyl acrylate (2 parts by mass), 2-ethylhexyl acrylate (4 parts by mass), methacrylic acid (1 part by mass), and cyclohexyl methacrylate (20 parts by mass) as monomers, to which UV absorber 1 (0.6 parts by mass) is added as the first stage. Methyl methacrylate (19 parts by mass), n-butyl acrylate (8 parts by mass), 2-ethylhexyl acrylate (21 parts by mass), methacrylic acid (2 parts by mass), and cyclohexyl methacrylate are used. The second stage involved using acrylate (18 parts by mass) with UV absorber 1 (0.8 parts by mass) added. The third stage involved using methyl methacrylate (10 parts by mass), n-butyl acrylate (19 parts by mass), 2-ethylhexyl acrylate (20 parts by mass), methacrylic acid (2 parts by mass), cyclohexyl methacrylate (15 parts by mass), and γ-methacryloyloxypropyltrimethoxysilane (1 part by mass) with UV absorber 1 (0.6 parts by mass) added. Polymerization was then carried out by a conventional method using emulsifier 1, emulsifier 2, initiator, and water.

[0056] (Example 12) Using the formulation shown in Table 1, an aqueous coating material 12 was obtained in the same manner as in Example 1. The obtained aqueous coating material 12 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1. Furthermore, the synthetic resin emulsion 12 (solids content 50% by mass, glass transition temperature 21°C) uses methyl methacrylate (43 parts by mass), n-butyl acrylate (2 parts by mass), 2-ethylhexyl acrylate (3 parts by mass), methacrylic acid (1 part by mass), and cyclohexyl methacrylate (17 parts by mass) as monomers in the first stage, and methyl methacrylate (17 parts by mass), n-butyl acrylate (10 parts by mass), 2-ethylhexyl acrylate (21 parts by mass), and meth The second stage involved using acrylic acid (2 parts by mass) and cyclohexyl methacrylate (18 parts by mass). The third stage involved using methyl methacrylate (8 parts by mass), n-butyl acrylate (21 parts by mass), 2-ethylhexyl acrylate (20 parts by mass), methacrylic acid (2 parts by mass), and cyclohexyl methacrylate (15 parts by mass), to which ultraviolet absorber 1 (0.6 parts by mass) was added. Polymerization was then carried out by a conventional method using emulsifier 1, initiator, and water.

[0057] (Example 13) Using the formulation shown in Table 1, an aqueous coating material 13 was obtained in the same manner as in Example 1. The obtained aqueous coating material 13 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1. Synthetic resin emulsion 13 (solids content 50% by mass, glass transition temperature 24°C) uses methyl methacrylate (50 parts by mass), n-butyl acrylate (3 parts by mass), 2-ethylhexyl acrylate (6 parts by mass), methacrylic acid (2 parts by mass), and cyclohexyl methacrylate (5 parts by mass) as monomers, to which ultraviolet absorber 1 (0.6 parts by mass) is added as the first stage, methyl methacrylate (30 parts by mass), n-butyl acrylate (12 parts by mass), 2-ethylhexyl acrylate (18 parts by mass), and methacrylate. The second stage involved using acrylic acid (3 parts by mass) and cyclohexyl methacrylate (5 parts by mass), to which ultraviolet absorber 1 (0.8 parts by mass) was added. The third stage involved using methyl methacrylate (20 parts by mass), n-butyl acrylate (17 parts by mass), 2-ethylhexyl acrylate (21 parts by mass), methacrylic acid (2 parts by mass), and cyclohexyl methacrylate (6 parts by mass), to which ultraviolet absorber 1 (0.6 parts by mass) was added. Polymerization was then carried out by a conventional method using emulsifier 1, initiator, and water.

[0058] (Example 14) Using the formulation shown in Table 1, an aqueous coating material 14 was obtained in the same manner as in Example 1. The obtained aqueous coating material 14 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0059] (Comparative Example 1) Using the formulation shown in Table 1, an aqueous coating material 15 was obtained in the same manner as in Example 1. The obtained aqueous coating material 15 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0060] (Comparative Example 2) Using the formulation shown in Table 1, an aqueous coating material 16 was obtained in the same manner as in Example 1. The obtained aqueous coating material 16 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0061] (Comparative Example 3) Using the formulation shown in Table 1, an aqueous coating material 17 was obtained in the same manner as in Example 1. The obtained aqueous coating material 17 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0062] (Comparative Example 4) Using the formulation shown in Table 1, an aqueous coating material 18 was obtained in the same manner as in Example 1. The crosslinking agent 2 is an oxazoline group-containing compound. The obtained aqueous coating material 18 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0063] (Comparative Example 5) Using the formulation shown in Table 1, an aqueous coating material 19 was obtained in the same manner as in Example 1. The obtained aqueous coating material 19 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0064] (Comparative Example 6) Using the formulation shown in Table 1, an aqueous coating material 20 was obtained in the same manner as in Example 1. The obtained aqueous coating material 20 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1.

[0065] (Comparative Example 7) Using the formulation shown in Table 1, an aqueous coating material 21 was obtained in the same manner as in Example 1. The obtained aqueous coating material 21 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1. UV absorber 2 is a triazine-based UV absorber.

[0066] (Comparative Example 8) Using the formulation shown in Table 1, an aqueous coating material 22 was obtained in the same manner as in Example 1. The obtained aqueous coating material 22 was subjected to weather resistance tests, stain resistance tests, and water resistance tests in the same manner as in Example 1. The evaluation results are shown in Table 1.

Claims

1. An aqueous coating material containing a synthetic resin emulsion, a crosslinking agent, an ultraviolet absorber, and colored particles with a particle size of 0.05 to 10 mm, The synthetic resin emulsion is obtained from a group of monomers including a carboxyl group-containing monomer. The crosslinking agent contains a carbodiimide group-containing compound, The ultraviolet absorber comprises oxalate anilide or a derivative thereof. The oxalic acid anilide or its derivative is a compound represented by the following formula (1): Formula (1) (R may be the same or different, and represents a hydrogen atom, an alkyl group having 1 to 24 carbon atoms, an alkoxy group, or an alkylthio group.) A water-based coating material characterized by the following features.

2. The aqueous coating material according to claim 1, characterized in that the amount of carboxyl group-containing monomers contained in the synthetic resin emulsion is 0.1% by mass or more and 20% by mass or less of the total amount of monomers.

3. The aqueous coating material according to claim 1, characterized in that the oxalic acid anilide or its derivative is contained in an amount of 0.1 parts by mass or more and 10 parts by mass or less per 100 parts by mass of the solid content of the synthetic resin emulsion.

4. The aqueous coating material according to claim 1, characterized in that the synthetic resin emulsion is obtained from a group of monomers including a cycloalkyl group monomer.

5. The aqueous coating material according to claim 4, characterized in that the content of cycloalkyl group-containing monomers in the synthetic resin emulsion is 5% by mass or more and 80% by mass or less of the total amount of monomers.

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