JP2023038171A - Aqueous coating - Google Patents

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 The present invention relates to a water-based coating material having excellent weather resistance, water resistance, and stain resistance.

Buildings and civil engineering structures are usually surface-finished with a covering material, which protects the frame from wind, rain, direct sunlight, etc., and also plays a role in maintaining aesthetics.
Such covering materials are required to have weather resistance against wind, rain, direct sunlight, etc., water resistance, and stain resistance.
On the other hand, in recent years, in consideration of non-pollution and safety, the use of water-based coating materials using synthetic resin emulsion as a binder has increased.

As one of the methods for improving the weather resistance, a method of introducing an ultraviolet absorber, a light stabilizer, etc. into the covering material is considered effective.
For example, Patent Literature 1 describes the use of a benzotriazole-based UV absorber to enhance weather resistance.

JP 2020-158578 A

However, in Patent Document 1, the stain resistance may be inferior, and it may be difficult to maintain the aesthetic appearance.

As a result of intensive studies to achieve excellent weather resistance, water resistance, and stain resistance, the present invention uses anilide oxalate or a derivative thereof as an ultraviolet absorber, and further uses carboxyl as a synthetic resin emulsion. By using a synthetic resin emulsion containing a group-containing monomer and a carbodiimide group-containing compound as a cross-linking agent, it was found that excellent weather resistance, water resistance, and stain resistance can be exhibited, and the present invention was completed. .

That is, the present invention has the following features.
1. An aqueous coating material containing a synthetic resin emulsion, a cross-linking agent and an ultraviolet absorber,
The synthetic resin emulsion is obtained from a monomer group containing a carboxyl group-containing monomer,
The cross-linking agent comprises a carbodiimide group-containing compound,
The UV absorber comprises an oxalic acid anilide or a derivative thereof;
An aqueous coating material characterized by:
2. 1. The content of the carboxyl group-containing monomer contained in the synthetic resin emulsion is 0.1% by weight or more and 20% by weight or less of the total amount of the monomers. Aqueous coating material according to.
3. 1. The synthetic resin emulsion 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. Aqueous coating material according to.
4. 1. The synthetic resin emulsion is obtained from a monomer group containing a cycloalkyl group-containing monomer. Aqueous coating material according to.
5. 1. The content of the cycloalkyl group-containing monomer contained in the synthetic resin emulsion is 5% by weight or more and 80% by weight or less based on the total amount of the monomers. Aqueous coating material according to.

The aqueous coating material of the present invention has excellent weather resistance, water resistance and stain resistance.

EMBODIMENT OF THE INVENTION Hereinafter, the form for implementing this invention is demonstrated.

The present invention is an aqueous coating material containing a synthetic resin emulsion, a cross-linking agent and an ultraviolet absorber, wherein the synthetic resin emulsion is obtained from a monomer group containing a carboxyl group-containing monomer, The cross-linking agent contains a carbodiimide group-containing compound, and the UV absorber contains oxalic acid anilide or a derivative thereof.
In the present invention, oxalic acid anilide or a derivative thereof is immobilized in such a manner that it enters into the crosslinked structure of a synthetic resin emulsion containing a carboxyl group-containing monomer and a carbodiimide group-containing compound, resulting in excellent weather resistance, water resistance, and stain resistance. I found that I can demonstrate my ability.

（Ｒは、同一でも異なっていてもよく、水素原子、炭素数１から２４のアルキル基、アルコキシ基、アルキルチオ基を示す。） The oxalic acid anilide or derivative thereof used in the present invention 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.)

Oxalanilide or derivatives thereof are specifically 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, 2-ethoxy-5-tert-butyl-2'-ethoxalanilide and its 2-ethoxy -mixtures with 2'-ethyl-5,4'-di-tert-butoxalanilides, mixtures of o- and p-methoxy-disubstituted oxalanilides and o- and p-ethoxy-disubstituted oxalanilides and the like, and one or more of these can be used in combination.
In the present invention, 2-ethyl-2'-ethoxyoxalanilide is particularly preferred.

Further, in the present invention, in addition to the above oxalic acid anilide or its derivatives, benzophenone-based, benzotriazole-based, triazine-based ultraviolet absorbers, and hindered amine-based light stabilizers, etc. are added to an extent that does not impair the effects of the present invention. can also be mixed into

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

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 and the like. More than one species can be used.

Further, in the present invention, a synthetic resin emulsion can be obtained by mixing other monomers in addition to the carboxyl group-containing monomer.
Other monomers 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 ) monomers having a cycloalkyl group such as 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 Acrylates, 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 ( hydroxyl group-containing monomers such as meth)acrylates and hydroxymethylcyclohexyl (meth)acrylates;
3-(meth)acryloxypropyltrimethoxysilane, 3-(meth)acryloxypropylmethyldimethoxysilane, 3-(meth)acryloxypropyltriethoxysilane, 3-(meth)acryloxypropylmethyldiethoxysilane, alkoxysilyl group-containing monomers such as vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriisopropoxysilane;
(Meth)acrylamide, ethyl (meth)acrylamide, N-ethyl (meth)acrylamide, N-isopropyl (meth)acrylamide, Nn-propyl (meth)acrylamide, N-cyclopropyl (meth)acrylamide, N-(meth)acrylamide ) acryloylpyrrolidine, 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) ) amide group-containing monomers such as acrylamide, N-methylol (meth)acrylamide, acrylamide glycolic acid, methyl acrylamide glycolate, and dimethoxyhydroxyethyl acrylamide,
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, oxytyl (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-methoxy Ethyl (meth)acrylate, 4-methoxybutyl (meth)acrylate, tripropylmethyl (meth)acrylate, triisopropylmethyl (meth)acrylate, tributylmethyl (meth)acrylate, triisobutylmethyl (meth)acrylate, tri-t-butylmethyl (meth) alkyl group-containing monomers such as acrylates,
(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) alkylene glycol chain-containing monomers such as polyethylene glycol-polypropylene glycol allyl ether,
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, amino groups such as 4-vinylpyridine contained monomers,
glycidyl (meth) acrylate, diglycidyl fumarate, 3,4-epoxycyclohexyl (meth) acrylate, 3,4-epoxyvinylcyclohexane, allyl glycidyl ether, ε-caprolactone-modified glycidyl (meth) acrylate, β-methylglycidyl (meth) ) glycidyl group-containing monomers such as acrylates,
Diacetone (meth)acrylate, diacetone (meth)acrylamide, acrolein, vinyl methyl ketone, vinyl ethyl ketone, vinyl (iso) butyl ketone, acetonyl acrylate, acryloxyalkylpropanals, methacryloxyalkylpropanals, 2-hydroxypropyl carbonyl group-containing monomers such as acrylate acetyl acetate, tandiol acrylate acetyl acetate, acetoacetoxyethyl (meth)acrylate, and acetoacetoxy allyl ester;
(meth) nitrile group-containing monomers such as acrylonitrile,
isocyanate group-containing monomers such as methacryloyl isocyanate,
oxazoline group-containing monomers such as vinyloxazoline, 2-vinyl-2-oxazoline, 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 acetoacetoxyallyl 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-tetramethylpiperidine, 1-(meth)acryloyl-4-(meth)acryloylamino-2 , 2,6,6-tetramethylpiperidine, 1-(meth)acryloyl-4-cyano-4-(meth)acryloylamino-2,2,6,6-tetramethylpiperidine, 4-crotonoyloxy-2, 2,6,6-tetramethylpiperidine, 4-crotonoylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonyloxy-2,2,6,6-tetramethylpiperidine and the like a piperidyl group-containing monomer of
vinylidene halide-based monomers such as vinylidene fluoride,
aromatic vinyl monomers such as styrene, 2-methylstyrene, chlorostyrene, vinyltoluene, t-butylstyrene, vinylanisole, and vinylnaphthalene;
sulfonic acid-containing monomers such as styrenesulfonic acid and vinylsulfonic acid;
2-hydroxy-4-(meth)acryloxybenzophenone, 2-hydroxy-5-(meth)acryloxybenzophenone, 2-hydroxy-4-{(meth)acryloxy-ethoxy}benzophenone, 2-hydroxy-4-{( benzophenone-based monomers such as meth)acryloxy-diethoxy}benzophenone, 2-hydroxy-4-{(meth)acryloxy-triethoxy}benzophenone,
2-{2′-hydroxy-5′-(meth)acryloxyethylphenyl}-2H-benzotriazole, 2-{2′-hydroxy-5′-(meth)acryloxyethyl-3-t-butylphenyl} -benzotriazoles such as 2H-benzotriazole, 3-(meth)acryloyl-2-hydroxypropyl-3-{3′-(2″-benzotriazole)-4-hydroxy-5-t-butyl}phenylpropionate system monomer,
other monomers such as ethylene, propylene, isoprene, butadiene, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl versatate, vinyl ether, vinyl ketone;
etc., and one or more of these can be used.
In the present invention, as other monomers, in particular, one or more monomers selected from alkyl group-containing monomers, alkoxysilyl group-containing monomers, and carboxyl group-containing monomers are included. is preferred.

The polymerization method of the synthetic resin emulsion used in the present invention is not particularly limited, but the above-mentioned various monomers (monomers) and, if necessary, various additives are mixed, and a commonly known polymerization method (emulsion polymerization method, suspension polymerization method, dispersion polymerization method, etc.) to produce a synthetic resin emulsion. Moreover, polymerization may be performed in one stage, or may be performed in multiple stages of two or more stages, or three or more stages.

Examples of additives include water, emulsifiers, initiators, solvents, dispersants, emulsion stabilizers, polymerization inhibitors, polymerization inhibitors, buffers, cross-linking agents, pH adjusters, chain transfer agents, catalysts, and the like. A necessary amount may be added according to various polymerization methods and purposes.

Examples of emulsifiers that can be used include anionic emulsifiers, cationic emulsifiers, nonionic emulsifiers, amphoteric emulsifiers, reactive emulsifiers, and the like, and are not particularly limited.
For example, alkylsulfonates such as sodium dodecylbenzenesulfonate and sodium dodecylsulfonate, alkylsulfates such as sodium dodecylbenzenesulfate and sodium dodecylsulfate, fatty acid salts such as ammonium laurate and sodium stearate, and rosinates , alkyl sulfosuccinates, dialkyl sulfosuccinates, α-olefin sulfonates, alkylnaphthalene sulfonates, polyoxyalkylene alkyl (aryl) sulfate ester salts, anionic salts such as polyoxyalkylene alkyl (aryl) sulfonate salts emulsifier,
Quaternary ammonium salts such as lauryltrialkylammonium salts, stearyltrialkylammonium salts, trialkylbenzylammonium salts, primary to tertiary amine salts, laurylpyridinium salts, benzalkonium salts, benzethonium salts, laurylamine acetate cationic surfactants such as
nonionic surfactants such as polyoxyalkylene alkyl ethers, polyoxyalkylene alkylphenyl ethers, polyalkylene glycols, polyoxyalkylene alkyl esters, polyoxyalkylene sorbitan alkyl esters, sorbitan alkyl esters;
Carboxybetaine type, sulfobetaine type, aminocarboxylic acid type, imidazoline derivative type amphoteric surfactants,
In addition, 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, poly Oxyalkylene alkyl propenyl alkyl ether, polyoxyalkylene alkyl propenylphenyl ether sulfate, polyoxyalkylene alkyl propenyl phenyl ether, polyoxyalkylene allyloxyalkylalkoxyalkyl ether sulfate, polyoxyalkylene allyloxyalkylalkoxyalkyl ether, poly Oxyalkylene allyloxyalkyl ether sulfate, polyoxyalkylene allyloxyalkyl ether, polyoxyalkylene styrenated propenyl phenyl ether sulfate, polyoxyalkylene styrenated propenyl phenyl ether, alkyl allyl sulfosuccinate, alkyl propenyl sulfosuccinate Ester salts, reactive emulsifiers such as (meth)acrylic acid polyoxyalkylene sulfonates, specifically, Eleminol JS-20 (manufactured by Sanyo Chemical Industries Co., Ltd.), Eleminol RS-30 (manufactured by Sanyo Chemical Industries Co., 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 (Daiichi Kogyo Seiyaku Co., Ltd.) Kogyo Seiyaku Co., Ltd.), Aqualon AR-30 (Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon BC-10 (Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon BC-20 (Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon BC-3025 (manufactured by Dai-ichi Kogyo Seiyaku Co., Ltd.), Adekari Soap SR-10 (manufactured by ADEKA Co., Ltd.), Adekari Soap SR-20 (manufactured by ADEKA Co., Ltd.), Adekari Soap SR-3025 (manufactured by ADEKA Co., Ltd.) ),ah Decalia Soap SE-10N (manufactured by ADEKA Co., Ltd.), Antox MS-60 (manufactured by Nippon Emulsion Co., Ltd.), Latemul PD-104 (manufactured by Kao Corporation), Latemul PD-105 (manufactured by Kao Corporation), Aqualon KN-10 (Daiichi Kogyo Seiyaku Co., Ltd.) Aqualon KN-20 (Daiichi Kogyo Seiyaku Co., Ltd.) Aqualon KN-30 (Daiichi Kogyo Seiyaku Co., Ltd.) Aqualon KN-5065 (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.), Aqualon RN-30 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Aqualon RN-50 (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.), Adekaria Soap ER-10 (stock ADEKA Corporation), Adekari Soap ER-20 (manufactured by ADEKA Co., Ltd.), Adekari Soap ER-30 (manufactured by ADEKA Co., Ltd.), Adekari Soap ER-40 (manufactured by ADEKA Co., Ltd.), Adekari Soap NE-10 (manufactured by ADEKA Co., Ltd.), Adekaria Soap NE-20 (manufactured by ADEKA Co., Ltd.), Adekaria Soap NE-30 (manufactured by ADEKA Co., Ltd.), Latemul PD-420 (manufactured by Kao Corporation), Latemul PD-430 (Kao Co., Ltd.), Latemul PD-450 (manufactured by Kao Corporation), and other reactive emulsifiers.
In the present invention, use of a reactive emulsifier is particularly preferred from the standpoint of weather resistance, water resistance, and the like.

Examples of initiators include persulfate initiators such as ammonium persulfate, potassium persulfate and sodium persulfate, 2,2′-azobisisobutyronitrile, 2,2′-azobis(2,4′-dimethyl azo initiators such as valeronitrile), 2,2'-azobis(2-amidinopropane) dihydrochloride, 2,2'-azobis(2-(2-imidazolin-2-yl)propane) dihydrochloride, dialkyl peroxides such as benzoyl peroxide, lauroyl peroxide and decanoyl peroxide; peroxy esters such as t-butyl peroxybenzoate; Peroxide initiators such as peroxides, redox initiators, photopolymerization initiators, reactive initiators, and the like can be used.

The polymerization temperature is not particularly limited, but may be about 20°C to 90°C.

The glass transition temperature of the synthetic resin emulsion is not particularly limited, but the glass transition temperature calculated from all monomer components constituting the synthetic resin emulsion is −10° C. or higher and 60° C. or lower, and further 0° C. or higher and 50° C. or lower. is preferred.
Generally, when the glass transition temperature is low, stain resistance tends to be poor, but in the present invention, excellent stain resistance and further excellent weather resistance can be obtained even when the glass transition temperature is low. Specifically, in the present invention, even when the glass transition temperature is −10° C. or more and less than 40° C., excellent stain resistance, weather resistance, and water resistance can be obtained.
The glass transition temperature is a value obtained from the FOX calculation formula.
Further, the glass transition temperature of each layer of the synthetic resin emulsion polymerized in two stages is that the inner layer is -40°C or higher and lower than 40°C (preferably -30°C or higher and 30°C or lower) (hereinafter also referred to as "low Tg"), An outer layer of 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”), or an inner layer with a high Tg and an outer layer with a low Tg can be used, In particular, in the present invention, it is preferable that the inner layer has a low Tg and the outer layer has a high Tg.
In addition, the glass transition temperature of each layer of the synthetic resin emulsion polymerized in three or more stages is, for example, high Tg for the inner layer and low Tg for the intermediate layer (if there are two or more intermediate layers, the total glass transition temperature of them). , the outermost layer is high Tg, inner layer (high Tg) / middle layer (low Tg) / outermost layer (low Tg), inner layer (high Tg) / middle layer (high Tg) / outermost layer (low Tg), inner layer (low Tg)/intermediate layer (high Tg)/outermost layer (high Tg), inner layer (low Tg)/intermediate layer (low Tg)/outermost layer (high Tg), inner layer (low Tg)/intermediate layer (high Tg)/ Outermost layer (low Tg) can be used, especially in the present invention inner layer (high Tg)/middle layer (low Tg)/outermost layer (high Tg) or inner layer (high Tg)/middle A layer (low Tg)/outermost layer (low Tg) is preferred.

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

The content of the carboxyl group-containing monomer is preferably 0.1% by weight or more and 20% by weight or less, more preferably 0.3% by weight or more and 15% by weight or less, based on the total amount of the monomers.
Within such a range, a water-based coating material having excellent weather resistance, water resistance, and stain resistance can be obtained.

Moreover, in the present invention, it is particularly preferable that a cycloalkyl group-containing monomer is included as a monomer. By using a synthetic resin emulsion containing a cycloalkyl group-containing monomer, better weather resistance and stain resistance can be exhibited.

The content of the cycloalkyl group-containing monomer is preferably 5% by weight or more and 80% by weight or less, more preferably 10% by weight or more and 70% by weight or less, based on the total amount of the monomers.
Within such a range, a water-based coating material having excellent weather resistance and stain resistance can be obtained.

The content of the oxalic acid anilide or its derivative is 0.1 to 10 parts by weight, further 0.3 to 8 parts by weight, and further 0 parts by weight with respect to 100 parts by weight of the solid content of the synthetic resin emulsion. .5 parts by weight or more and 6 parts by weight or less.
The oxalic acid anilide or its derivative can be mixed during the production of the synthetic resin emulsion, or can be added after the production of the synthetic resin emulsion.
In the present invention, mixing during the production of the synthetic resin emulsion is particularly preferred. By mixing during the production of the synthetic resin emulsion, it is possible to obtain a water-based coating material with even better weather resistance, water resistance and stain resistance.

The cross-linking 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 tautomeric cyanamide group (NC-NH-), and such a carbodiimide group-containing compound is By using it as a cross-linking agent, it cross-links with the carboxyl groups in the synthetic resin emulsion to form a strong coating film, and incorporates oxalic acid anilide into the cross-linked structure to improve weather resistance, water resistance, and further can form a coating film with excellent stain resistance.
Such a carbodiimide group-containing compound can be obtained using a diisocyanate compound as a starting material.
Examples of diisocyanate compounds include aliphatic isocyanates such as hexamethylene diisocyanate, 1,4-tetramethylene diisocyanate, 2-methylpentane-1,5-diisocyanate, and lysine diisocyanate; isophorone diisocyanate, norbornane diisocyanate, and hydrogenated tolylene diisocyanate. , hydrogenated xylene diisocyanate, hydrogenated diphenylmethane diisocyanate, alicyclic diisocyanates such as hydrogenated tetramethylxylene diisocyanate; 2,4'-dicyclohexylmethane diisocyanate, 4,4'-dicyclohexylmethane diisocyanate, 2,4'- Diphenylmethane diisocyanate, 4,4'-diphenylmethane diisocyanate, 4,4'-diphenyl ether diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, 3,3'-dimethoxy-4,4'-biphenyl diisocyanate, o-tolidine diisocyanate, naphthyl Diisocyanate, 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, 3,3′-dimethyl-4,4′-diphenyl ether diisocyanate, 3,3′-dimethyl-4,4′-diphenyl ether diisocyanate, etc. Aromatic diisocyanates and the like can be mentioned, and one or more of these can be used.

Also, the carbodiimide group-containing compound may be one in which some or all of the isocyanate groups are modified with a compound having a functional group capable of reacting with the isocyanate groups.
Functional groups capable of reacting with isocyanate groups include hydroxyl groups, amine groups, carboxyl groups, epoxy groups, and the like, and can be appropriately selected and used.
In the present invention, it is particularly preferable to use glycols such as alkylene glycol and alkylene glycol alkyl ether.

The content (solid content) of the carbodiimide group-containing compound is 0.1 to 10 parts by weight, preferably 0.3 to 8 parts by weight, relative to 100 parts by weight of the solid content of the synthetic resin emulsion. is preferred. The carbodiimide group-containing compound can be mixed during the production of the synthetic resin emulsion, or can be added after the production of the synthetic resin emulsion.

Moreover, in the present invention, a cross-linking agent other than the carbodiimide group-containing compound can also be included. Examples of cross-linking 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, metal complexes, and the like.

In addition to the components described above, the water-based coating material of the present invention may contain various additives as long as they do not impair the effects of the present invention. Such additives include, for example, water, dispersion media such as solvents, pigments, aggregates, film-forming aids, plasticizers, antifreeze agents, preservatives, antifungal agents, antialgae agents, antibacterial agents, antibacterial agents, Foaming agents, leveling agents, coupling agents, thickeners, pigment dispersants, anti-settling agents, anti-sagging agents, surface control agents, wetting agents, pH control agents, fibers, antioxidants, curing catalysts, matting agents etc.

Examples of pigments include titanium oxide, 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, and yellow iron oxide. , Titanium Yellow, Ultramarine Blue, Prussian Blue, Cobalt Blue, Cobalt Green, Iron Chromium Composite Oxide, Manganese Bismuth Composite Oxide, Manganese Yttrium Composite Oxide, Manganese Iron Cobalt Composite Oxide, etc. , pyrazolone-based, anthraquinone-based, perylene-based, quinacridone-based, disazo-based, isoindolinone-based, benzimidazole-based, phthalocyanine-based, quinophthalone-based organic coloring pigments, pearl pigments, fluorescent pigments, phosphorescent pigments, metallic pigments, etc. Extender pigments such as functional pigments, heavy calcium carbonate, precipitated calcium carbonate, kaolin, talc, clay, china clay, china clay, barium sulfate, barium carbonate, silica powder, diatomaceous earth, pearl pigments, aluminum pigments, metallic pigments , phosphorescent pigments, fluorescent pigments, and the like. These can be used alone or in combination of two or more.

The water-based coating material in the present invention is suitable for applications where the coating film is exposed to wind, rain, direct sunlight, etc., such as a topcoat material, a finishing material, a protective material, etc. (a coating material that forms the outermost surface coating film on a substrate). can be used for The aqueous coating material of the present invention can be finished by one or more coats, for example concrete, mortar, siding board, extruded board, ALC, gypsum board, perlite board, tile, glass board, wood It can be applied to various substrates such as plates, plastic plates, and metal plates.
In addition, these base materials must not be subjected to any surface treatment (filler treatment, putty treatment, surfacer treatment, sealer treatment, etc.), undercoat material, intermediate coating material, or existing paint film that has already been formed. can also be applied.

As the coating method, various methods such as brush coating, roller coating, spray coating, and gun coating can be employed. The amount applied during coating is preferably 0.03 to 8.0 kg/m ² , more preferably 0.05 to 6.0 kg/m ² per coating. Moreover, after coating is performed once and the coating film is dried, the next coating (overcoating) can be performed. The drying temperature is preferably -10 to 50°C, more preferably -5 to 40°C.
The coating amount of the water-based coating material of the present invention may be appropriately set according to the intended use, and is preferably about 0.1 kg/m ² to 8.0 kg/m ² .

Examples are shown below to further clarify the features of the present invention. It should be noted that the invention is not limited to the examples herein.

(Example 1)
In the formulation shown in Table 1, synthetic resin emulsion 1 (solid content 50% by weight, glass transition temperature 20 ° C.), ultraviolet absorber 1 (2-ethyl-2'-ethoxyoxalanilide), cross-linking agent 1 (4, Glycol-modified polycarbodiimide obtained from 4'-dicyclohexylmethane diisocyanate) and additives (film-forming aid, antifoaming agent) were mixed to obtain an aqueous coating material 1.
The resulting water-based coating material 1 was subjected to the following weather resistance test, stain resistance test, and water resistance test. Evaluation results are shown in Table 1.
Synthetic resin emulsion 1 uses, as monomers, 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), and emulsifier 1 ( polyoxyethylene alkyl sulfate ammonium salt), an initiator (ammonium persulfate), and water, and polymerization was carried out by a conventional method.

(Weather resistance test)
The resulting water-based coating material 1 is spray-coated on a slate plate pre-coated with an acrylic resin-based color clear paint (black), and dried for 24 hours under standard conditions (temperature 23° C., relative humidity 50%). A coating having a dry film thickness of 0.1 mm was formed to obtain a specimen.
The obtained test specimen was subjected to 80 cycles of accelerated testing using an accelerated weather resistance tester, 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 of 8 hours). After that, the appearance of the film was confirmed, and the state of occurrence of defects (swelling, peeling, cracking, discoloration, etc.) was evaluated. The evaluation was carried out on a 4-point scale (excellent: ◎>○>Δ>×: poor), with “⊚” indicating that no problem occurred and “×” indicating that a problem clearly occurred.

(Stain resistance test)
The resulting water-based coating material 1 was spray-coated on a slate plate pre-coated with an acrylic resin color clear paint (white) and dried for 24 hours to form a coating with a dry film thickness of 0.1 mm. , a test specimen was obtained.
The obtained specimen was placed vertically facing south in Ibaraki City, Osaka Prefecture, and exposed to the outdoors for 6 months. After 6 months, the surface contamination of the specimen was visually evaluated.
The evaluation was made on a 4-point scale (excellent: ◎>○>Δ>×: inferior), with “⊚” indicating no contamination and “×” indicating significant contamination.

(Water resistance test)
The resulting water-based coating material 1 was spray-coated on a slate plate pre-coated with an acrylic resin color clear paint (black) and dried for 24 hours to form a coating with a dry film thickness of 0.1 mm. , a test specimen was obtained.
The obtained specimen was immersed in water at 23° C. for 24 hours, and the color difference before and after immersion in water was measured with a spectrophotometer and evaluated.
The evaluation was carried out on a 4-point scale (excellent: ⊚>∘>Δ>×: poor), with "⊚" indicating a color difference of less than 5 and "×" indicating a color difference of 20 or more.

(Example 2)
Synthetic resin emulsion 2 (solid content: 50% by weight, glass transition temperature: 28° C.), cross-linking agent 1 and additives were mixed according to the composition shown in Table 1 to obtain water-based coating material 2 .
The same weather resistance test, stain resistance test, and water resistance test as in Example 1 were performed on the water-based coating material 2 thus obtained. Evaluation results are shown in Table 1.
The synthetic resin emulsion 2 uses, as monomers, 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). Agent 1 (2-ethyl-2'-ethoxyoxalanilide) (2 parts by weight) was added, and emulsifier 1, an initiator and water were used to carry out polymerization in a conventional manner.

(Example 3)
Synthetic resin emulsion 3 (solid content: 50% by weight, glass transition temperature: 28° C.), ultraviolet absorber 1, cross-linking agent 1, and additives were mixed according to the composition shown in Table 1 to obtain water-based coating material 3.
The same weather resistance test, stain resistance test and water resistance test as in Example 1 were performed on the water-based coating material 3 thus obtained. Evaluation results are shown in Table 1.
The synthetic resin emulsion 3 contains 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. part) in the first stage, 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), cyclohexyl methacrylate (20 parts by weight) It was used as the second stage, and furthermore, using emulsifier 1, an initiator and water, polymerization was carried out by a conventional method.

(Example 4)
Synthetic resin emulsion 4 (solid content: 50% by weight, glass transition temperature: 28° C.), cross-linking agent 1, and additives were mixed according to the composition shown in Table 1 to obtain water-based coating material 4.
The same weather resistance test, stain resistance test and water resistance test as in Example 1 were performed on the water-based coating material 4 thus obtained. Evaluation results are shown in Table 1.
The synthetic resin emulsion 4 contains 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. part), and UV absorber 1 (0.4 parts by weight) was added to this in the first stage, methyl methacrylate (40 parts by weight), n-butyl acrylate (10 parts by weight), 2-ethylhexyl acrylate (7 parts by weight) parts by weight), methacrylic acid (3 parts by weight), and cyclohexyl methacrylate (40 parts by weight), to which UV absorber 1 (0.4 parts by weight) is added, is used as the second stage, and emulsifier 1 , an initiator, and water in a conventional manner.

(Example 5)
Synthetic resin emulsion 5 (solid content: 50% by weight, glass transition temperature: 28° C.), cross-linking agent 1 and additives were mixed according to the composition shown in Table 1 to obtain water-based coating material 5 .
The same weather resistance test, stain resistance test and water resistance test as in Example 1 were performed on the water-based coating material 5 thus obtained. Evaluation results are shown in Table 1.
The synthetic resin emulsion 5 contains, as monomers, 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), and cyclohexyl methacrylate (35 parts by weight). part), using cyclohexyl acrylate (10 parts by weight), to which UV absorber 1 (2 parts by weight) was added, the first stage, 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), cyclohexyl acrylate (10 parts by weight), to which UV absorber 1 (2 parts by weight) was added was used as the second step, and polymerization was carried out by a conventional method using emulsifier 1, an initiator and water.

(Example 6)
Synthetic resin emulsion 6 (solid content: 50% by weight, glass transition temperature: 28° C.), cross-linking agent 1 and additives were mixed according to the composition shown in Table 1 to obtain water-based coating material 6 .
The same weather resistance test, stain resistance test and water resistance test as in Example 1 were performed on the water-based coating material 6 thus obtained. Evaluation results are shown in Table 1.
The synthetic resin emulsion 6 contains 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), and cyclohexyl methacrylate (24 parts by weight) as monomers. part), γ-methacryloyloxypropyltrimethoxysilane (1 part by weight) was added to this with UV absorber 1 (1 part by weight) for the first step, 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), cyclohexyl methacrylate (40 parts by weight), and UV absorber 1 (1 part by weight) were added. It was used as the second stage, and furthermore, using emulsifier 1, an initiator and water, polymerization was carried out by a conventional method.

(Example 7)
Synthetic resin emulsion 7 (solid content: 50% by weight, glass transition temperature: 28° C.), cross-linking agent 1 and additives were mixed according to the composition shown in Table 1 to obtain water-based coating material 7 .
The same weather resistance test, stain resistance test and water resistance test as in Example 1 were performed on the water-based coating material 7 thus obtained. Evaluation results are shown in Table 1.
The synthetic resin emulsion 7 contains 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. part), and UV absorber 1 (1 part by weight) was added to this in the first stage, 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), cyclohexyl methacrylate (40 parts by weight), to which UV absorber 1 (1 part by weight) is added, is used as the second stage, and emulsifier 2 (polyoxyethylene Allyloxyalkylalkoxyalkylether sulfate salt), an initiator, and water were used for polymerization in a conventional manner.

(Example 8)
Synthetic resin emulsion 8 (solid content: 50% by weight, glass transition temperature: 28° C.), cross-linking agent 1 and additives were mixed according to the composition shown in Table 1 to obtain water-based coating material 8 .
The same weather resistance test, stain resistance test and water resistance test as in Example 1 were performed on the water-based coating material 8 thus obtained. Evaluation results are shown in Table 1.
The synthetic resin emulsion 8 contains 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. part), and UV absorber 1 (0.6 parts by weight) was added to this in the first stage, methyl methacrylate (14 parts by weight), n-butyl acrylate (9 parts by weight), 2-ethylhexyl acrylate (29 parts by weight) parts by weight), methacrylic acid (2 parts by weight), cyclohexyl methacrylate (14 parts by weight), and UV absorber 1 (0.8 parts by weight) was added to the second stage, methyl methacrylate (21 parts by weight) part), n-butyl acrylate (10 parts by weight), 2-ethylhexyl acrylate (12 parts by weight), methacrylic acid (2 parts by weight), and cyclohexyl methacrylate (21 parts by weight), to which UV absorber 1 (0.6 parts by weight Part) was added as the third step, and further polymerization was carried out by a conventional method using emulsifier 1, an initiator and water.

(Example 9)
Synthetic resin emulsion 9 (solid content: 50% by weight, glass transition temperature: 28° C.), cross-linking agent 1 and additives were mixed according to the composition shown in Table 1 to obtain water-based coating material 9 .
The same weather resistance test, stain resistance test, and water resistance test as in Example 1 were performed on the water-based coating material 9 thus obtained. Evaluation results are shown in Table 1.
The synthetic resin emulsion 9 contains 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. part), and UV absorber 1 (0.6 parts by weight) was added to this in the first stage, methyl methacrylate (18 parts by weight), n-butyl acrylate (9 parts by weight), 2-ethylhexyl acrylate (21 parts by weight) parts by weight), methacrylic acid (2 parts by weight), cyclohexyl methacrylate (18 parts by weight), and UV absorber 1 (0.8 parts by weight) was added to the second stage, methyl methacrylate (15 parts by weight) parts), n-butyl acrylate (10 parts by weight), 2-ethylhexyl acrylate (24 parts by weight), methacrylic acid (2 parts by weight), and cyclohexyl methacrylate (15 parts by weight), to which UV absorber 1 (0.6 parts by weight Part) was added as the third step, and further polymerization was carried out by a conventional method using emulsifier 1, an initiator and water.

(Example 10)
Synthetic resin emulsion 10 (solid content: 50% by weight, glass transition temperature: 28° C.), cross-linking agent 1 and additives were mixed according to the composition shown in Table 1 to obtain water-based coating material 10 .
The same weather resistance test, stain resistance test, and water resistance test as in Example 1 were performed on the water-based coating material 10 thus obtained. Evaluation results are shown in Table 1.
The synthetic resin emulsion 10 contains 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. part), and UV absorber 1 (0.6 parts by weight) was added to this in the first stage, methyl methacrylate (18 parts by weight), n-butyl acrylate (9 parts by weight), 2-ethylhexyl acrylate (21 parts by weight) parts by weight), methacrylic acid (2 parts by weight), cyclohexyl methacrylate (18 parts by weight), and UV absorber 1 (0.8 parts by weight) was added to the second stage, methyl methacrylate (14 parts by weight part), 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), γ-methacryloyloxypropyltrimethoxysilane (1 part by weight) was used, and an ultraviolet absorber 1 (0.6 parts by weight) was added thereto as the third stage, and further emulsifier 2, an initiator, and water were used to carry out polymerization by a conventional method. .

(Example 11)
Synthetic resin emulsion 11 (solid content: 50% by weight, glass transition temperature: 28° C.), ultraviolet absorber 1, cross-linking agent 1, and additives were mixed according to the composition shown in Table 1 to obtain water-based coating material 11.
The same weather resistance test, stain resistance test, and water resistance test as in Example 1 were performed on the water-based coating material 11 thus obtained. Evaluation results are shown in Table 1.
The synthetic resin emulsion 11 uses methyl methacrylate (106 parts by weight), n-butyl acrylate (89 parts by weight), and methacrylic acid (5 parts by weight) as monomers, and further uses emulsifier 1, an initiator, and water. Polymerization was carried out by a conventional method.

(Comparative example 1)
Aqueous coating material 12 was obtained by mixing synthetic resin emulsion 1 and additives according to the formulation shown in Table 1.
The same weather resistance test, stain resistance test, and water resistance test as in Example 1 were performed on the obtained water-based coating material 12 . Evaluation results are shown in Table 1.

(Comparative example 2)
Synthetic resin emulsion 1, ultraviolet absorber 1, and additives were mixed according to the formulation shown in Table 1 to obtain water-based coating material 13.
The same weather resistance test, stain resistance test, and water resistance test as in Example 1 were performed on the obtained water-based coating material 13 . Evaluation results are shown in Table 1.

(Comparative Example 3)
Synthetic resin emulsion 1, cross-linking agent 1, and additives were mixed according to the formulation shown in Table 1 to obtain water-based coating material 14.
The same weather resistance test, stain resistance test, and water resistance test as in Example 1 were performed on the water-based coating material 14 thus obtained. Evaluation results are shown in Table 1.

(Comparative Example 4)
Synthetic resin emulsion 1, ultraviolet absorber 1, cross-linking agent 2 (oxazoline group-containing compound) and additives were mixed according to the composition shown in Table 1 to obtain water-based coating material 15.
The same weather resistance test, stain resistance test, and water resistance test as in Example 1 were performed on the obtained water-based coating material 15 . Evaluation results are shown in Table 1.

(Comparative Example 5)
Aqueous coating material 16 was obtained by mixing synthetic resin emulsion 11, ultraviolet absorber 1, and additives according to the formulation shown in Table 1.
The same weather resistance test, stain resistance test, and water resistance test as in Example 1 were performed on the obtained water-based coating material 16 . Evaluation results are shown in Table 1.

(Comparative Example 6)
Aqueous coating material 17 was obtained by mixing synthetic resin emulsion 11, cross-linking agent 1, and additives according to the formulation shown in Table 1.
The same weather resistance test, stain resistance test, and water resistance test as in Example 1 were performed on the water-based coating material 17 thus obtained. Evaluation results are shown in Table 1.

(Comparative Example 7)
Synthetic resin emulsion 11, UV absorber 2 (triazine-based UV absorber), and additives were mixed according to the composition shown in Table 1 to obtain water-based coating material 18 .
The same weather resistance test, stain resistance test, and water resistance test as in Example 1 were performed on the water-based coating material 18 thus obtained. Evaluation results are shown in Table 1.

(Comparative Example 8)
Aqueous coating material 19 was obtained by mixing synthetic resin emulsion 11, ultraviolet absorber 2, cross-linking agent 1, and additives according to the formulation shown in Table 1.
The same weather resistance test, stain resistance test, and water resistance test as in Example 1 were performed on the water-based coating material 19 thus obtained. Evaluation results are shown in Table 1.

Claims (5)

An aqueous coating material containing a synthetic resin emulsion, a cross-linking agent and an ultraviolet absorber,
The synthetic resin emulsion is obtained from a monomer group containing a carboxyl group-containing monomer,
The cross-linking agent comprises a carbodiimide group-containing compound,
The UV absorber comprises an oxalic acid anilide or a derivative thereof;
An aqueous coating material characterized by: 2. The water-based coating material according to claim 1, wherein the content of the carboxyl group-containing monomer contained in the synthetic resin emulsion is 0.1% by weight or more and 20% by weight or less of the total amount of the monomers. 2. The water-based coating material according to claim 1, wherein said oxalic acid anilide or its derivative is contained in an amount of 0.1 to 10 parts by weight based on 100 parts by weight of solid content of said synthetic resin emulsion. 2. The water-based coating material according to claim 1, wherein the synthetic resin emulsion is obtained from a monomer group containing a cycloalkyl group-containing monomer. 2. The water-based coating material according to claim 1, wherein the content of the cycloalkyl group-containing monomer contained in the synthetic resin emulsion is 5% by weight or more and 80% by weight or less of the total amount of the monomers.