Water-based covering materials

Abstract

To provide an aqueous coating having excellent weather resistance, water resistance, and stain resistance.SOLUTION: An aqueous coating comprises: a synthetic resin emulsion obtained from a monomer group including a carboxyl group-containing monomer; a crosslinker that contains a carbodiimide group-containing compound; and an ultraviolet absorber that contains oxalic anilide or a derivative thereof.SELECTED DRAWING: None

Description

Technical Field

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

Background Art

[0002] Buildings and civil structures are usually surface-finished with coating materials, which protect the structure from wind, rain, direct sunlight, etc., and also play a role in maintaining aesthetics. Such coating materials are required to have weather resistance, water resistance, and stain resistance against wind, rain, direct sunlight, etc. On the other hand, in recent years, considering environmental friendliness and safety, the use of aqueous coating materials using synthetic resin emulsions as binders has been increasing.

[0003] As one method for enhancing weather resistance, a method of introducing an ultraviolet absorber, a light stabilizer, etc. into the coating material has been considered effective. For example, in Patent Document 1, it is described that weather resistance is enhanced by using a benzotriazole-based ultraviolet absorber.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] However, in Patent Document 1, there are cases where stain resistance is poor and it is difficult to maintain aesthetics.

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, and an ultraviolet absorber, 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, Oxalic acid anilides or their derivatives include 2-methyl-2'-ethoxyoxalanilide, 2-ethyl-2'-ethoxyoxalanilide, 4,4'-dimethoxyoxalanilide, 4,4'-dioctyloxyoxalanilide, 2,2'-diethoxyoxalanilide, 2,2'-dioctyloxy-5,5'-di-tertiary butoxalanilide, and 2,2'-didodecyloxy-5,5'-di-tertiary butoxalanilide. One or more selected from tributoxalanilide, N,N'-bis(3-dimethylaminopropyl)oxalamide, 2-ethoxy-5-tertiary butyl-2'-ethoxalanilide and a mixture thereof with 2-ethoxy-2'-ethyl-5,4'-di-tertiary butoxalanilide, a mixture of o- and p-methoxy-disubstituted oxalanilides, and a mixture of o- and p-ethoxy-disubstituted oxalanilides. 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 weight or more and 20% by weight 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 weight or more and 10 parts by weight or less of the oxalic acid anilide or its derivative per 100 parts by weight 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 1, characterized in that the content of cycloalkyl group-containing monomers in the synthetic resin emulsion is 5% by weight or more and 80% by weight 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, and an ultraviolet absorber, 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) TIFF0007876381000001.tif3080 (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 its derivatives specifically include 2-methyl-2'-ethoxyoxanilide, 2-ethyl-2'-ethoxyoxanilide, 4,4'-dimethoxyoxanilide, 4,4'-dioctyloxyoxanilide, 2,2'-diethoxyoxanilide, 2,2'-dioctyloxy-5,5'-di-tert-butoxyoxanilide, 2,2'-didodecyloxy-5,5'-di-tert-butoxyoxanilide, N,N'-bis(3-dimethylaminopropyl)oxalamide, 2-ethoxy-5-tert-butyl-2'-ethoxyoxanilide and its mixture with 2-ethoxy-2'-ethyl-5,4'-di-tert-butoxyoxanilide, mixtures of o- and p-methoxy-disubstituted oxanilides, mixtures of o- and p-ethoxy-disubstituted oxanilides, etc. One or more of these can be mixed and used. In the present invention, it is particularly preferable to use 2-ethyl-2'-ethoxyoxanilide.

[0013] In addition, in the present invention, in addition to the above-mentioned oxanilide or its derivatives, ultraviolet absorbers such as benzophenone-based, benzotriazole-based, and triazine-based, and light stabilizers such as hindered amine-based can be mixed to such an extent that the effects of the present invention are not impaired.

[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 monomer having a carboxyl group include (meth)acrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid, isocrotonic acid, salicylic acid, cinnamic acid, etc. One or more of these can be used.

[0016] In the present invention, in addition to the carboxyl group-containing monomer, other monomers can be mixed to obtain a synthetic resin emulsion. Examples of other monomers include Monomers having cycloalkyl groups, such as cyclopentyl (meth)acrylate, cyclohexyl (meth)acrylate, methylcyclohexyl (meth)acrylate, t-butylcyclohexyl (meth)acrylate, cyclooctyl (meth)acrylate, cyclododecyl (meth)acrylate, and 4-tert-butylcyclohexyl (meth)acrylate. 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-Hydroxy Hydroxyl group-containing monomers such as butyl (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, vinyltrimethoxysisiliane, vinyltriethoxysisiliane, and vinyltriisopropoxysilane. (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. Alkyl group-containing monomers such as 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-amyl (meth)acrylate, octyl (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, trit-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, (methoxy)polyethylene glycol-polypropylene glycol allyl ether, etc., 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 that the other monomers include one or more monomers selected from alkyl group-containing monomers, alkoxysilyl group-containing monomers, and carboxyl group-containing monomers.

[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 or more steps, or even three or more steps.

[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 a synthetic resin emulsion is not particularly limited, but it is preferable that the glass transition temperature calculated from all the monomer components constituting the synthetic resin emulsion is 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. The glass transition temperature is a value that can be calculated using FOX's formula. Furthermore, the glass transition temperature of each layer of the two-stage polymerized synthetic resin emulsion can be -40°C or higher and less than 40°C (preferably -30°C or higher and 30°C or lower) (hereinafter also referred to as "low Tg") for the inner layer, 40°C or higher and 100°C or lower (preferably 50°C or higher and 90°C or lower) (hereinafter also referred to as "high Tg") for the outer layer, or the inner layer can have a high Tg and the outer layer a low Tg. In particular, in the present invention, the inner layer has a low Tg and the outer layer has a high Tg. Furthermore, the glass transition temperatures of each layer in a synthetic resin emulsion polymerized in three or more stages are, for example, high Tg for the inner layer, low Tg for the intermediate layer (if there are two or more intermediate layers, the sum of their glass transition temperatures), and high Tg for the outermost layer; inner layer (high Tg) / intermediate layer (low Tg) / outermost layer (low Tg); inner layer (high Tg) / intermediate layer (high Tg) / outermost layer (low Tg); and inner layer (low Tg) / intermediate layer. Layers with high Tg / outermost layer (high Tg), inner layer (low Tg) / intermediate layer (low Tg) / outermost layer (high Tg), or inner layer (low Tg) / intermediate layer (high Tg) / outermost layer (low Tg) can be used, and in particular in the present invention, inner layer (high Tg) / intermediate layer (low Tg) / outermost layer (high Tg), or inner layer (high Tg) / intermediate layer (low Tg) / outermost layer (low Tg) are preferred.

[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 carboxyl group-containing monomers is preferably 0.1% by weight or more and 20% by weight or less, and more preferably 0.3% by weight or more and 15% by weight 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 cycloalkyl group-containing monomer as the monomer. By using a synthetic resin emulsion containing a cycloalkyl group-containing monomer, even better weather resistance and stain resistance can be achieved.

[0026] The content of cycloalkyl group-containing monomers is preferably 5% by weight or more and 80% by weight or less, and more preferably 10% by weight or more and 70% by weight 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 and stain resistance.

[0027] The content of oxalic acid anilide or its derivatives is preferably 0.1 parts by weight or more and 10 parts by weight or less, more preferably 0.3 parts by weight or more and 8 parts by weight or less, and more preferably 0.5 parts by weight or more and 6 parts by weight or less, per 100 parts by weight of solids of the synthetic resin emulsion. Anilide oxalate or its derivatives can be mixed during the production of synthetic resin emulsions or added after the production of synthetic resin emulsions. In this invention, it is particularly preferable to mix the material during the manufacturing of the synthetic resin emulsion. By mixing it during the manufacturing of the synthetic resin emulsion, an aqueous coating material with even better weather resistance, water resistance, and stain resistance can be obtained.

[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 weight or more and 10 parts by weight or less, and more preferably 0.3 parts by weight or more and 8 parts by weight or less, per 100 parts by weight of 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] In addition to the components described above, the aqueous coating material of the present invention may also contain various additives, provided that they do not impair the effects of the present invention. Examples of such additives include dispersion media such as water and solvents, pigments, aggregates, 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, antioxidants, curing catalysts, matting agents, and the like.

[0033] 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.

[0034] The aqueous coating material of the present invention can be suitably used in applications where the coating film is exposed to wind, rain, direct sunlight, etc., for example, as a topcoat, finishing material, protective material, etc. (a coating material that forms the outermost coating film on a substrate). The aqueous coating material of the present invention can be finished by one or more coats and can be applied to various substrates such as concrete, mortar, siding boards, extruded boards, ALC, gypsum boards, perlite boards, tiles, glass boards, wood boards, plastic boards, and metal boards. 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.

[0035] Various painting methods can be employed, such as brush 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 / m2 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. The amount of aqueous coating material of the present invention applied can be set appropriately according to the application, but preferably 0.1 kg / m². 2 From 8.0 kg / m 2 A certain degree is acceptable. [Examples]

[0036] The following examples illustrate the features of the present invention. However, the present invention is not limited to the examples provided herein.

[0037] (Example 1) A water-based coating material 1 was obtained by mixing synthetic resin emulsion 1 (50% by weight solids, glass transition temperature 20°C), ultraviolet absorber 1 (2-ethyl-2'-ethoxyoxalanilide), crosslinking agent 1 (glycol-modified polycarbodiimide obtained by 4,4'-dicyclohexylmethane diisocyanate), and additives (film-forming aid, defoaming agent) 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 a conventional method with monomers consisting of methyl methacrylate (75 parts by weight), n-butyl acrylate (85 parts by weight), methacrylic acid (5 parts by weight), and cyclohexyl methacrylate (35 parts by weight), further polymerized with emulsifier 1 (polyoxyethylene alkyl sulfate ammonium salt), initiator (ammonium persulfate), and water.

[0038] (Weather resistance test) A water-based coating material 1 was spray-applied to a slate board that had been pre-painted with an acrylic resin-based clear color paint (black), and dried for 24 hours under standard conditions (temperature 23°C, relative humidity 50%) to form a coating with a dry film thickness of 0.1 mm, thereby obtaining a test specimen. 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.

[0039] (Stain resistance test) A water-based coating material 1 was spray-applied to a slate board that had been pre-painted with an acrylic resin-based clear color paint (white), and dried for 24 hours to form a coating with a dry film thickness of 0.1 mm, thereby obtaining a test specimen. 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.

[0040] (Water resistance test) A water-based coating material 1 was spray-applied to a slate board that had been pre-painted with an acrylic resin-based clear color paint (black), and dried for 24 hours to form a film with a dry thickness of 0.1 mm, thereby obtaining a test specimen. 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 "×".

[0041] [Table 1]

[0042] (Example 2) A water-based coating material 2 was obtained by mixing synthetic resin emulsion 2 (50% by weight solids, glass transition temperature 28°C), crosslinking agent 1, and additives according to the formulation shown in Table 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 was prepared by using methyl methacrylate (70 parts by weight), 2-ethylhexyl acrylate (65 parts by weight), methacrylic acid (5 parts by weight), and cyclohexyl methacrylate (60 parts by weight) as monomers, adding ultraviolet absorber 1 (2-ethyl-2'-ethoxyoxalanilide) (2 parts by weight), and then polymerizing it using an emulsifier 1, an initiator, and water by a conventional method.

[0043] (Example 3) A water-based coating material 3 was obtained by mixing synthetic resin emulsion 3 (50% by weight solids, glass transition temperature 28°C), ultraviolet absorber 1, crosslinking agent 1, and additives according to the formulation shown in Table 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 was polymerized by a conventional method using methyl methacrylate (30 parts by weight), n-butyl acrylate (10 parts by weight), 2-ethylhexyl acrylate (43 parts by weight), methacrylic acid (2 parts by weight), and cyclohexyl methacrylate (15 parts by weight) as monomers in the first stage, and methyl methacrylate (61 parts by weight), n-butyl acrylate (10 parts by weight), 2-ethylhexyl acrylate (6 parts by weight), methacrylic acid (3 parts by weight), and cyclohexyl methacrylate (20 parts by weight) as monomers in the second stage, and further polymerized using emulsifier 1, initiator, and water.

[0044] (Example 4) A synthetic resin emulsion 4 (50% by weight solids, glass transition temperature 28°C), crosslinking agent 1, and additives were mixed according to the formulation shown in Table 1 to obtain an aqueous coating material 4. 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 was prepared by using methyl methacrylate (24 parts by weight), n-butyl acrylate (10 parts by weight), 2-ethylhexyl acrylate (40 parts by weight), methacrylic acid (2 parts by weight), and cyclohexyl methacrylate (24 parts by weight) as monomers, with UV absorber 1 (0.4 parts by weight) added to this mixture as the first stage. The second stage used methyl methacrylate (40 parts by weight), n-butyl acrylate (10 parts by weight), 2-ethylhexyl acrylate (7 parts by weight), methacrylic acid (3 parts by weight), and cyclohexyl methacrylate (40 parts by weight), with UV absorber 1 (0.4 parts by weight) added to this mixture as the second stage. Polymerization was then carried out by a conventional method using emulsifier 1, initiator, and water.

[0045] (Example 5) A water-based coating material 5 was obtained by mixing synthetic resin emulsion 5 (solids content 50% by weight, glass transition temperature 28°C), crosslinking agent 1, and additives according to the formulation shown in Table 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 was prepared by using methyl methacrylate (6 parts by weight), n-butyl acrylate (5 parts by weight), 2-ethylhexyl acrylate (42 parts by weight), methacrylic acid (2 parts by weight), cyclohexyl methacrylate (35 parts by weight), and cyclohexyl acrylate (10 parts by weight) as monomers, with UV absorber 1 (2 parts by weight) added to this mixture as the first stage. The second stage used methyl methacrylate (6 parts by weight), n-butyl acrylate (5 parts by weight), 2-ethylhexyl acrylate (1 part by weight), methacrylic acid (3 parts by weight), cyclohexyl methacrylate (75 parts by weight), and cyclohexyl acrylate (10 parts by weight), with UV absorber 1 (2 parts by weight) added to this mixture as the second stage. Polymerization was then carried out by a conventional method using emulsifier 1, initiator, and water.

[0046] (Example 6) A synthetic resin emulsion 6 (50% by weight solids, glass transition temperature 28°C), crosslinking agent 1, and additives were mixed according to the formulation shown in Table 1 to obtain an aqueous coating material 6. 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 was prepared by using methyl methacrylate (24 parts by weight), n-butyl acrylate (10 parts by weight), 2-ethylhexyl acrylate (39 parts by weight), methacrylic acid (2 parts by weight), cyclohexyl methacrylate (24 parts by weight), and γ-methacryloyloxypropyltrimethoxysilane (1 part by weight) as monomers, with UV absorber 1 (1 part by weight) added to this mixture as the first stage. The second stage used methyl methacrylate (39 parts by weight), n-butyl acrylate (10 parts by weight), 2-ethylhexyl acrylate (8 parts by weight), methacrylic acid (3 parts by weight), and cyclohexyl methacrylate (40 parts by weight), with UV absorber 1 (1 part by weight) added to this mixture as the second stage. Polymerization was then carried out by a conventional method using emulsifier 1, initiator, and water.

[0047] (Example 7) A water-based coating material 7 was obtained by mixing synthetic resin emulsion 7 (50% by weight solids, glass transition temperature 28°C), crosslinking agent 1, and additives according to the formulation shown in Table 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 was prepared by using methyl methacrylate (24 parts by weight), n-butyl acrylate (10 parts by weight), 2-ethylhexyl acrylate (40 parts by weight), methacrylic acid (2 parts by weight), and cyclohexyl methacrylate (24 parts by weight) as monomers, with UV absorber 1 (1 part by weight) added to this mixture as the first stage. The second stage used methyl methacrylate (40 parts by weight), n-butyl acrylate (10 parts by weight), 2-ethylhexyl acrylate (7 parts by weight), methacrylic acid (3 parts by weight), and cyclohexyl methacrylate (40 parts by weight), with UV absorber 1 (1 part by weight) added to this mixture as the second stage. Further polymerization was carried out by conventional methods using emulsifier 2 (polyoxyethylene allyloxyalkyl alkoxyalkyl ether sulfate), initiator, and water.

[0048] (Example 8) A water-based coating material 8 was obtained by mixing synthetic resin emulsion 8 (50% by weight solids, glass transition temperature 28°C), crosslinking agent 1, and additives according to the formulation shown in Table 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 uses methyl methacrylate (29 parts by weight), n-butyl acrylate (1 part by weight), 2-ethylhexyl acrylate (6 parts by weight), methacrylic acid (1 part by weight), and cyclohexyl methacrylate (29 parts by weight) as monomers, to which UV absorber 1 (0.6 parts by weight) is added as the first stage, methyl methacrylate (14 parts by weight), n-butyl acrylate (9 parts by weight), 2-ethylhexyl acrylate (29 parts by weight), methacrylic acid (2 parts by weight), and cyclohexyl methacrylate as monomers. The second stage involved using 14 parts by weight of chlorohexyl methacrylate, to which UV absorber 1 (0.8 parts by weight) was added. The third stage involved using 21 parts by weight of methyl methacrylate, 10 parts by weight of n-butyl acrylate, 12 parts by weight of 2-ethylhexyl acrylate, 2 parts by weight of methacrylic acid, and 21 parts by weight of cyclohexyl methacrylate, to which UV absorber 1 (0.6 parts by weight) was added. Polymerization was then carried out by a conventional method using emulsifier 1, initiator, and water.

[0049] (Example 9) A synthetic resin emulsion 9 (50% by weight solids, glass transition temperature 28°C), crosslinking agent 1, and additives were mixed according to the formulation shown in Table 1 to obtain an aqueous coating material 9. 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 uses methyl methacrylate (31 parts by weight), n-butyl acrylate (1 part by weight), 2-ethylhexyl acrylate (2 parts by weight), methacrylic acid (1 part by weight), and cyclohexyl methacrylate (31 parts by weight) as monomers, to which UV absorber 1 (0.6 parts by weight) is added as the first stage, methyl methacrylate (18 parts by weight), n-butyl acrylate (9 parts by weight), 2-ethylhexyl acrylate (21 parts by weight), methacrylic acid (2 parts by weight), and cyclohexyl methacrylate as monomers. The second stage involved using 18 parts by weight of chlorohexyl methacrylate, to which UV absorber 1 (0.8 parts by weight) was added. The third stage involved using 15 parts by weight of methyl methacrylate, 10 parts by weight of n-butyl acrylate, 24 parts by weight of 2-ethylhexyl acrylate, 2 parts by weight of methacrylic acid, and 15 parts by weight of cyclohexyl methacrylate, to which UV absorber 1 (0.6 parts by weight) was added. Polymerization was then carried out by a conventional method using emulsifier 1, initiator, and water.

[0050] (Example 10) A water-based coating material 10 was obtained by mixing synthetic resin emulsion 10 (solids content 50% by weight, glass transition temperature 28°C), crosslinking agent 1, and additives according to the formulation shown in Table 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 uses methyl methacrylate (31 parts by weight), n-butyl acrylate (1 part by weight), 2-ethylhexyl acrylate (2 parts by weight), methacrylic acid (1 part by weight), and cyclohexyl methacrylate (31 parts by weight) as monomers, to which UV absorber 1 (0.6 parts by weight) is added as the first stage, and methyl methacrylate (18 parts by weight), n-butyl acrylate (9 parts by weight), 2-ethylhexyl acrylate (21 parts by weight), methacrylic acid (2 parts by weight), and cyclohexyl methacrylate (18 parts by weight) as monomers. The second stage involved using (parts by weight) and adding UV absorber 1 (0.8 parts by weight) to it. The third stage involved using methyl methacrylate (14 parts by weight), n-butyl acrylate (10 parts by weight), 2-ethylhexyl acrylate (24 parts by weight), methacrylic acid (2 parts by weight), cyclohexyl methacrylate (15 parts by weight), and γ-methacryloyloxypropyltrimethoxysilane (1 part by weight) and adding UV absorber 1 (0.6 parts by weight) to it. Polymerization was then carried out by a conventional method using emulsifier 2, initiator, and water.

[0051] (Example 11) A synthetic resin emulsion 11 (50% by weight solids, glass transition temperature 28°C), ultraviolet absorber 1, crosslinking agent 1, and additives were mixed according to the formulation shown in Table 1 to obtain an aqueous coating material 11. 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 was prepared by polymerization using methyl methacrylate (106 parts by weight), n-butyl acrylate (89 parts by weight), and methacrylic acid (5 parts by weight) as monomers, and further polymerized using emulsifier 1, initiator, and water by a conventional method.

[0052] (Comparative Example 1) A water-based coating material 12 was obtained by mixing synthetic resin emulsion 1 and additives according to the formulation shown in Table 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.

[0053] (Comparative Example 2) A water-based coating material 13 was obtained by mixing synthetic resin emulsion 1, ultraviolet absorber 1, and additives according to the formulation shown in Table 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.

[0054] (Comparative Example 3) A synthetic resin emulsion 1, a crosslinking agent 1, and an additive were mixed according to the formulation shown in Table 1 to obtain an aqueous coating material 14. 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.

[0055] (Comparative Example 4) A water-based coating material 15 was obtained by mixing synthetic resin emulsion 1, ultraviolet absorber 1, crosslinking agent 2 (oxazoline group-containing compound), and additives according to the formulation shown in Table 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.

[0056] (Comparative Example 5) A synthetic resin emulsion 11, an ultraviolet absorber 1, and an additive were mixed according to the formulation shown in Table 1 to obtain an aqueous coating material 16. 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.

[0057] (Comparative Example 6) A synthetic resin emulsion 11, a crosslinking agent 1, and an additive were mixed according to the formulation shown in Table 1 to obtain an aqueous coating material 17. 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.

[0058] (Comparative Example 7) A synthetic resin emulsion 11, ultraviolet absorber 2 (triazine-based ultraviolet absorber), and additives were mixed according to the formulation shown in Table 1 to obtain an aqueous coating material 18. 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.

[0059] (Comparative Example 8) A synthetic resin emulsion 11, ultraviolet absorber 2, crosslinking agent 1, and additives were mixed according to the formulation shown in Table 1 to obtain an aqueous coating material 19. 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.

Claims

1. A water-based coating material containing a synthetic resin emulsion, a crosslinking agent, and an ultraviolet absorber, 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 anilide oxalate or a derivative thereof. Oxalic acid anilides or their derivatives include 2-methyl-2'-ethoxyoxalanilide, 2-ethyl-2'-ethoxyoxalanilide, 4,4'-dimethoxyoxalanilide, 4,4'-dioctyloxyoxalanilide, 2,2'-diethoxyoxalanilide, 2,2'-dioctyloxy-5,5'-di-tertiary butoxalanilide, and 2,2'-didodecyloxy-5,5'-di-tertiary butoxalanilide. One or more selected from tributoxalanilide, N,N'-bis(3-dimethylaminopropyl)oxalamide, 2-ethoxy-5-tertiary butyl-2'-ethoxalanilide and a mixture thereof with 2-ethoxy-2'-ethyl-5,4'-di-tertiary butoxalanilide, a mixture of o- and p-methoxy-disubstituted oxalanilides, and a mixture of o- and p-ethoxy-disubstituted oxalanilides. 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 weight or more and 20% by weight or less of the total amount of monomers.

3. The aqueous coating material according to claim 1, characterized in that it contains 0.1 parts by weight or more and 10 parts by weight or less of the oxalic acid anilide or its derivative with respect to 100 parts by weight 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 1, characterized in that the content of cycloalkyl group-containing monomers in the synthetic resin emulsion is 5% by weight or more and 80% by weight or less of the total amount of monomers.

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