JP2008239779A - Low staining aqueous coating composition and object coated with the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low staining aqueous coating composition which can reduce rain stripe-like stains compared with conventional coating compositions when coating films comprising the aqueous coating composition is exposed outdoors, can especially prevent the stains just after the coating films are formed, has excellent durability, and has good storage stability as a coating, and to provide an object coated with the same. <P>SOLUTION: The low staining aqueous coating composition comprises (A) an aqueous resin composition and (B) an aqueous dispersion obtained by subjecting 100 pts.mass of one or more α,β-ethylenically unsaturated monomers to emulsion polymerization using 1-300 pts.mass (solids) of water-dispersed inorganic particles having an average particle size of 4-100 nm as an emulsification stabilizer. The object coated with the composition is also disclosed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a low-contamination aqueous coating composition used for building interior materials, exterior materials, and the like, and coatings thereof. Specifically, by applying a paint containing an emulsion synthesized using water-dispersed inorganic particles, the coating surface becomes hydrophilic and water wettability is improved, and rainwater penetrates into the interface between the coating film and contaminants. The present invention relates to a low-fouling water-based coating composition capable of forming a coating film having a function of washing out contaminants and having excellent stain resistance and sustained effect, and a coating thereof.

  Conventionally, organic solvent dilution type paints have been used in many cases. However, environmental problems such as sick house syndrome and the diffusion of organic solvents into the atmosphere have been raised, and conversion to water-based paints is proceeding at an accelerated pace. On the other hand, consumer needs are also increasing expectations for the long-term durability and high functionality of these products.

  Also, if non-polar pollutants such as dust in the atmosphere, oily substances, and carbon contained in exhaust gas adhere to and accumulate on the coating film of building materials, etc., they accumulate without being washed away by rainwater, The condition is uneven and easily noticeable. As a technique for improving the contamination of these coating films, there has been proposed a method for improving water wettability by making a coating film hydrophilic by adding a hydrophilic component such as colloidal silica (for example, Patent Document 1 and 2). However, it has been difficult to maintain good contamination resistance for a long time due to the outflow of hydrophilic components due to repeated rainfall.

  Furthermore, in order to suppress the outflow, it has been proposed to reduce the outflow by chemically bonding the hydrophilic component and the polymer, or by adding an alkoxysilane compound and polymerizing it by hydrolysis condensation polymerization. However, since a surfactant is used as an essential component during emulsion polymerization, the hydrophilicity of the entire coating film is improved, resulting in extremely poor water resistance and warm water whitening resistance (for example, Patent Document 3).

Furthermore, although improvement of these coating film performances is proposed by using a reactive surfactant (for example, Patent Document 4), it is a fundamental solution to both the rain-stain stain resistance and the water resistance. The current situation is not.
JP 2005-120165 A Japanese Patent Application Laid-Open No. 11-116885 Japanese Patent No. 2,637,955 JP 59-217702 A

  The object of the present invention is to solve the above-mentioned problems, and there is little contamination on the surface of the coating film due to adsorption of dust and oily substances in the atmosphere, and it is difficult to leave a trace of rain after the rain. It is an object of the present invention to provide a low-staining aqueous coating composition and a coating thereof that form a coating film that is excellent in water resistance and excellent in water resistance.

In accordance with the present invention,
(A) an aqueous resin composition, and
(B) One or two or more α, β-ethylenically unsaturated monomers 100 using 1 to 300 parts by mass of water-dispersed inorganic particles (solid content) having an average particle size of 4 to 100 nm as an emulsion stabilizer Provided is a low-fouling aqueous coating composition characterized by containing an aqueous dispersion obtained by emulsion polymerization of parts by mass, and a coating thereof.

  As described above, the present invention provides a low-fouling water-based coating composition that can form a coating film having good stain resistance and excellent water resistance for a long period of time when used in a water-based paint, and a coating thereof. It became possible.

  Hereinafter, embodiments of the present invention will be described in detail.

  As a result of repeating various studies to achieve the above object, the present inventors have obtained (A) an aqueous resin composition, and (B) water-dispersed inorganic particles having an average particle size of 4 to 100 nm (solid content). 1) to 300 parts by mass of an emulsion stabilizer, and containing an aqueous dispersion obtained by emulsion polymerization of 100 parts by mass of one or more α, β-ethylenically unsaturated monomers. It has been found that when the characteristic low-pollution aqueous coating composition is used in paints, a coating film having good stain resistance and excellent water resistance can be formed over a long period of time.

(A) The aqueous resin composition may be any resin composition for paints using water as a medium, and preferably has the following (1) emulsion having a uniform structure and a heterophase structure obtained by a multistage emulsion polymerization method. A water-soluble resin comprising one or both of the emulsions,
(2) a water-soluble resin having a weight average molecular weight of 5,000 to 100,000, including polyvinyl alcohol, polyamide, polyacrylic acid, polyacrylate, or a copolymer thereof;
(3) An aqueous resin composition obtained by phase conversion and forced emulsification of acrylic, alkyd, epoxy resin, polyester, polyurethane, etc. polymerized and / or condensed in an organic solvent medium with water,
Is mentioned.

  Emulsions with a uniform structure enable the formation of a dense coating film and provide a coating film with excellent water permeation resistance and clearness.The heterophasic emulsion is formed by combining monomers with different glass transition temperatures. By using these emulsions, such as being able to obtain a coating film with excellent film properties and excellent non-adhesiveness, the range of coating film properties formed can be expanded.

  In addition, by using a water-soluble resin containing polyvinyl alcohol, polyamide, polyacrylic acid, polyacrylate, or a copolymer thereof, it is possible to design a paint with excellent coating workability and a more hydrophilic coating film. By forming the film, a coating film having excellent stain resistance can be obtained. The water-soluble resins preferably have a weight average molecular weight of 5,000 to 100,000. When the weight average molecular weight is less than 5,000, the toughness and weather resistance of the coating film tend to be poor. On the other hand, when the weight average molecular weight exceeds 100,000, the viscosity becomes high and the coating workability is deteriorated.

  Aqueous resin composition obtained by phase inversion and forced emulsification of acrylic, alkyd, epoxy, polyester, polyurethane resin, etc., polymerized and / or condensed in organic solvent medium with water, has excellent adhesion and toughness to the substrate. An excellent coating film can be formed.

  (B) The aqueous dispersion is one or two or more kinds of α, β-ethylenically unsaturated groups using 1 to 300 parts by mass of water-dispersed inorganic particles (solid content) having an average particle size of 4 to 100 nm as an emulsion stabilizer. It can be obtained by emulsion polymerization of 100 parts by mass of monomer. Monomer batch charging method in which monomers are charged in batch, monomer dropping method in which monomers are continuously dropped, or these Are generally produced by the following production method.

  First, a part of the above-mentioned one or two or more α, β-ethylenically unsaturated monomers are charged in a reaction vessel capable of being heated and stirred, and water-dispersed inorganic particles having an average particle size of 4 to 100 nm and water (Preferably deionized water), an initiator and, if necessary, a chain transfer agent are charged and mixed thoroughly. While this mixed solution is kept at a temperature of 20 ° C. to 80 ° C., the remaining one or more α, β-ethylenically unsaturated monomers are added dropwise little by little, and the mixture is emulsified for about 1 to 24 hours. When the polymerization is carried out, an aqueous dispersion (B) using water-dispersed inorganic particles as a dispersion stabilizer is obtained. In this case, the amount of the water-dispersed inorganic particles having an average particle diameter of 4 to 100 nm is 1 to 300 parts by mass with respect to 100 parts by mass of one or more α, β-ethylenically unsaturated monomers, and more preferably. 10 to 250 parts by mass. When the amount is less than 1 part by mass, the stability during storage and the storage stability are poor, and the resulting coating film also has a high contact angle with pure water and a stain resistance effect cannot be obtained. On the other hand, when the amount exceeds 300 parts by mass, the amount of free water-dispersed inorganic particles increases, so the amount of elution from the coating film increases with time, which causes a decrease in gloss and a weakening of the coating film. .

  Examples of the α, β-ethylenically unsaturated monomer that can be used in the aqueous dispersion (B) include the following monomers. Methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, t-butyl acrylate, hexyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, nonyl acrylate, decyl acrylate, dodecyl Acrylate, n-amyl acrylate, isoamyl acrylate, lauryl acrylate, stearyl acrylate, methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, Isobutyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) Acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, n-amyl (meth) acrylate, isoamyl ( (Meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, methoxypropyl (Meth) acrylate, ethoxypropyl (meth) acrylate, styrene, α-methylstyrene, chlorostyrene, vinyltoluene, acrylonitrile, etc. One or more selected monomers can be used.

  Furthermore, in the present invention, as an α, β-ethylenically unsaturated monomer, a carboxyl group-containing monomer, an amino group-containing monomer, an amide group-containing monomer, a hydroxyl group-containing monomer, an alkoxysilyl group-containing It is preferable to include at least one selected from the group of monomers.

  Specific examples of the carboxyl group-containing monomer include acrylic acid, (meth) acrylic acid, fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, and crotonic acid.

  As amino group-containing monomers, 2-aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, 3-aminopropyl (meth) acrylate, 2-butylaminoethyl (meth) acrylate, and 4-vinylpyridine Etc.

  Examples of the amide group-containing monomer include acrylamide, (meth) acrylamide, N-methyl (meth) acrylamide, N-ethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-dimethylaminopropyl ( And meth) acrylamide and N-vinyl-2-pyrrolidone.

  Examples of hydroxyl group-containing monomers include allyl alcohol, 2-hydroxyethyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl acrylate, 2-hydroxybutyl (meth) acrylate, and polyethylene glycol (meth). Examples thereof include acrylate and polypropylene glycol (meth) acrylate.

  Examples of the alkoxysilyl group-containing monomer include vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, γ- (meth) acryloxypropyltrimethoxysilane, and γ- (meth) acryloxy. Propyltriethoxysilane, β- (meth) acryloxyethyltrimethoxysilane, β- (meth) acryloxyethyltriethoxysilane, γ- (meth) acryloxypropylmethyldimethoxysilane, γ- (meth) acryloxypropylmethyl Diethoxysilane, γ- (meth) acryloxypropylmethyldipropoxysilane, γ- (meth) acryloxybutylphenyldimethoxysilane, γ- (meth) acryloxypropyldimethylmethoxysilane, and γ- (meth) acryloxypropyl Ethyl silane, and the like.

  Among these, acrylic acid, (meth) acrylic acid, 2-hydroxyethyl (meth) acrylate, acrylamide, dimethylamino (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide, 4-vinylpyridine, N- Monomers such as vinyl-2-pyrrolidone and γ- (meth) acryloxypropyltrimethoxysilane are excellent in chemically and / or electrically adsorbing and fixing water-dispersed inorganic particles on the surface of polymer particles. Therefore, it is particularly preferable. Monomers having other functional groups do not contribute to the adsorption / immobilization of water-dispersed inorganic particles, but they can be used in combination. For example, glycidyl (meth) acrylate, allyl glycidyl ether, an epoxy group-containing monomer or oligomer obtained by reaction of an epoxy compound having two or more glycidyl groups with an ethylenically unsaturated monomer having an active hydrogen atom Isocyanate-containing monomers such as (meth) acryloyl isocyanate, isocyanate ethyl (meth) acrylate, m-isopropenyl-α, α-dimethylbenzyl methacrylate; N-methylol acrylamide or vinyl acetate having an N-methylol group, chloride Representative examples include vinyl, ethylene, butadiene, acrylonitrile, dialkyl fumarate, and the like. Also about these, the 1 type (s) or 2 or more types of monomer can be utilized.

  Furthermore, in order to improve the function of the obtained coating film, it is also possible to introduce a crosslinked structure. In general, the crosslinked structure is roughly classified into two types: “intraparticle crosslinked structure” and “interparticle crosslinked structure”.

  By incorporating this “intraparticle cross-linking structure” and “interparticle cross-linking structure” into the emulsion particles, the coating performance such as toughness, blocking resistance, non-adhesiveness, and solvent resistance can be greatly improved. Can be improved.

  Examples of monomers for obtaining the intra-particle / inter-crosslinked structure are listed as follows.

Intraparticle crosslinking: A monomer having two or more polymerizable unsaturated double bonds in the molecule.
A method using divinylbenzene, ethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate or the like;
Combining monomers having functional groups that react with each other at temperature during the emulsion polymerization reaction, for example, ethylenically unsaturated monomers having a functional group in combination such as a carboxyl group and a glycidyl group, or a hydroxyl group and an isocyanate group Using a monomer mixture selectively containing
A monomer mixture containing a hydrolyzable silyl group-containing ethylenically unsaturated monomer such as (meth) acryloxypropyl trimethoxysilane, (meth) acryloxypropylmethyldimethoxysilane, etc. How to use;
It can be produced by such a method.

  Interparticle cross-linking: The most typical example is a method in which an ethylenically unsaturated monomer having a carbonyl group is copolymerized and then a compound having two or more hydrazide groups is mixed in the molecule.

  Examples of the carbonyl group-containing ethylenically unsaturated monomer include acrolein, diacetone (meth) acrylamide, formylstyrene, (meth) acryloxyalkylpropanal, diacetone (meth) acrylate, acetonyl (meth) acrylate, and acetoacetoxy. Examples include ethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate-acetyl acetate, butanediol-1,4-acrylate-acetyl acrylate, vinyl ethyl ketone, and vinyl isobutyl ketone. In particular, acrolein, diacetone acrylamide and vinyl methyl ketone are preferable.

  Examples of the compound having two or more hydrazide groups in the molecule as a pair of the carbonyl group include carbohydrazide, oxalic acid dihydrazide, malonic acid dihydrazide, succinic acid dihydrazide, glutaric acid dihydrazide, adipic acid dihydrazide, and sebacic acid. Examples include dihydrazide, dodecanedioic acid dihydrazide, isophthalic acid dihydrazide, citric acid trihydrazide, 1,2,4-benzenetrihydrazide, and thiocarbodihydrazide. Among these, carbohydrazide, adipic acid dihydrazide, and succinic acid dihydrazide are preferable from the viewpoint of dispersibility in the emulsion and water resistance.

  Further, when (C) hydrolyzable silane represented by the following general formula (a) is used, the surface OH group of colloidal silica is cross-linked to improve the film strength, and durability, stain resistance, hardness , Heat resistance becomes better.

_{^{(R 1) n -Si- (R}} 2) 4-n (a)
In the formula (a), n is an integer of 0 to 3, and R ¹ is a hydrogen atom, an aliphatic hydrocarbon group having 1 to 16 carbon atoms, an aryl group having 5 to 10 carbon atoms, or a cyclohexane having 5 to 6 carbon atoms. It is selected from an alkyl group, a vinyl group, an alkyl group having 1 to 10 carbon atoms, or an alkyl group having 1 to 10 carbon atoms. The n R ¹ may be the same or different. R ² is selected from an alkoxy group having 1 to 8 carbon atoms, an acetoxy group, or a hydroxyl group. (4-n) pieces of R ² may be the same or different.

  General examples of the hydrolyzable silane include vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris (2-methoxyethoxy) silane, N- (2-aminoethyl) 3-aminopropylmethyldimethoxysilane, N- ( 2-aminoethyl) 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, 2- (3,4-epoxycyclohexyl) ) Ethyltrimethoxysilane, 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane, 3-methacryloxypropyltrimethoxysilane, 3-mercaptopropyltrimethoxysilane and the like.

  Furthermore, in order to improve the weather resistance and light resistance of the resulting coating film, it is possible to incorporate a light stabilizing function and an ultraviolet absorbing function.

  Specific examples of the polymerizable photostable monomer include 4- (meth) acryloyloxy-2,2,6,6-tetramethylpiperidine, 4- (meth) acryloylamino-2,2,6,6. -Tetramethylpiperidine, 4- (meth) acryloyloxy-1,2,2,6,6-pentamethylpiperidine, 4- (meth) acryloylamino-1,2,2,6,6-pentamethylpiperidine, 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- (meth) acryloyl-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1- (meth) acrylo Ru-4-cyano-4- (meth) acryloylamino-2,2,6,6-tetramethylpiperidine, 1-crotonoyl-4-crotonoyloxy-2,2,6,6-tetramethylpiperidine and the like Can be mentioned.

  Specific examples of the polymerizable ultraviolet absorbing monomer include 2- [2′-hydroxy-5 ′-(methacryloyloxymethyl) phenyl] -2H-benzotriazole and 2- [2′-hydroxy-5 ′. -(Methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxypropyl) phenyl] -2H-benzotriazole, 2- [2'-hydroxy-5'-( Methacryloyloxyhexyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy-3′-t-butyl-5 ′-(methacryloyloxyethyl) phenyl] -2H-benzotriazole, 2- [2′-hydroxy -5′-t-butyl-3 ′-(methacryloyloxyethyl) phenyl] -2H-benzoto Azole, 2- [2′-hydroxy-5 ′-(methacryloyloxyethyl) phenyl] -5-chloro-2H-benzotriazole, 2- [2′-hydroxy-5 ′-(methacryloyloxyethyl) phenyl] -5 -Methoxy-2H-benzotriazole, 2- [2'-hydroxy-5 '-(methacryloyloxyethyl) phenyl] -5-cyano-2H-benzotriazole, 2- [2'-hydroxy-5'-(methacryloyloxy) Ethyl) phenyl] -5-t-butyl-2H-benzotriazole, 2- [2′-hydroxy-5 ′-(methacryloyloxyethyl) phenyl] -5-nitro-2H-benzotriazole, and the like.

  Of course, it is also possible to use a non-reactive light stabilizer or ultraviolet absorber together during the polymerization.

In the present invention, it is preferable to use water-dispersed colloidal silica (SiO ₂ ) as water-dispersed inorganic particles having an average particle diameter of 4 to 100 nm used in the production of the aqueous dispersion (B). By being within the above range, water-dispersed spherical colloidal silica having an average particle diameter of 50 nm or less is more preferable because of excellent stability during polymerization and hydrophilicity of the coating film surface. When the average particle size of the water-dispersed colloidal silica is larger than 100 nm, the polymer particles are also easily settled, so that the storage stability is lowered. On the other hand, the lower limit of the average particle diameter is 4 nm because it indicates an average particle diameter that is readily available at present, and if it is less than 4 nm, it becomes very expensive and difficult to obtain, and the usage is narrowed. Further, the water-dispersed colloidal silica may have a spherical shape, a chain shape, an irregular shape, or the like. In the present invention, these can be used, and preferably one of the spherical shape and the chain shape is used. You can use both. The shape and average particle diameter of the water-dispersed colloidal silica can be confirmed by observation with an electron microscope.

  Specific examples of water-dispersed colloidal silica include, for example, Snowtex ST-20, ST-O, ST-C, ST-S, ST-N manufactured by Nissan Chemical Industries, Ltd., and ADEKA Corporation. Adelite AT-20, AT-20N, AT-20A, AT-300 and the like can be mentioned. Of these, one or more water-dispersed colloidal silicas may be used in combination.

  As the polymerization initiator used at the time of emulsion polymerization, those conventionally used for radical polymerization can be used, but water-soluble ones are preferable, for example, potassium persulfate, ammonium persulfate, and the like. Persulfates such as 2,2′-azobis (2-aminodipropane) hydrochloride, 4,4′-azobis-cyanovaleric acid, 2,2′-azobis (2-methylbutanamide oxime) di Examples thereof include azo compounds such as hydrochloride tetrahydrate; peroxides such as hydrogen peroxide and t-butyl hydroperoxide. Furthermore, a redox system in which a reducing agent such as L-ascorbic acid or sodium thiosulfate is combined with ferrous sulfate or the like can also be used.

  Examples of the chain transfer agent include alkyl mercaptans such as lauryl mercaptan, n-butyl mercaptan, t-butyl mercaptan, octyl mercaptan, n-dodecyl mercaptan, thioglycolic acid-2-ethylhexyl, 2-methyl-t-butyl. Examples thereof include thiophenol, carbon tetrabromide, and α-methylstyrene dimer. By appropriately using these, the gloss, film formability, and non-adhesiveness of the coating film can be controlled.

  When emulsion polymerization of the aqueous dispersion (B) is performed in the coating composition of the present invention, stable particles are obtained even when no anionic, nonionic, or cationic surfactant that is usually used as an emulsifier is used. Therefore, the surfactant contained in the coating formed by the coating composition can be reduced, and the water resistance, weather resistance and stain resistance can be improved.

  Examples of the surfactant used as an emulsifier in the present invention include fatty acid salts such as sodium lauryl sulfate, alkylbenzene sulfonates such as higher alcohol sulfate esters and sodium dodecylbenzenesulfonate, and polyoxyethylene alkyl ether sulfates. , Polyoxynonylphenyl ether sulfonate ammonium, polyoxyethylene-polyoxypropylene glycol ether sulfate, sulfonic acid group or sulfate ester group and polymerizable carbon-carbon unsaturated double bond in the molecule, so-called reactivity Anionic surfactants such as emulsifiers; polyoxyethylene alkyl ether, polyoxyethylene nonylphenyl ether, sorbitan fatty acid ester, polyoxyethylene fatty acid ester, polyoxyethylene-polyoxypro Nonionic surfactants such as ren block copolymers or reactive nonionic surfactants having a skeleton and a polymerizable carbon-carbon unsaturated double bond in the molecule; alkylamine salts and quaternary ammonium salts And the like, and the like.

  When emulsion polymerization of the aqueous dispersion (B) is performed in the coating composition of the present invention, polyvinyl alcohol (including modified type), hydroxyalkyl cellulose, polyalkylene glycol, water-soluble resin is used as a colloid stabilizer. When a polymer surfactant is used, it is preferable not to use these at all because the properties such as water resistance, hot water whitening resistance, weather resistance and the like of the coating film are remarkably lowered in the same manner as the above-mentioned emulsifier.

  The aqueous dispersion (B) thus obtained has a pH of 6 because water-dispersed inorganic particles may coagulate and solidify and precipitate in an acidic region below pH 6 and a strong base region higher than pH 12. It is preferable that it is -12, Furthermore, it is more preferable that it is pH 7-11. When the pH of the aqueous dispersion (B) after synthesis is outside this range, the pH can be adjusted using a generally used pH adjuster.

  As the pH adjuster, various nitrogen-containing basic compounds conventionally known as neutralizers can be used without particular limitation. Specifically, for example, trimethylamine, alkylamines such as triethylamine, tributylamine, triethanolamine, dimethylethanolamine, diethanolamine, monoethanolamine, N-methyldiethanolamine, N, N-dimethylethanolamine, ethylpropanolamine Representative examples include alcohol amines such as volatile nitrogen-containing basic compounds such as morpholine and ammonia. Of these, one or more pH adjusting agents may be used in combination.

  Further, γ-aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltrimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyl Dimethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldiethoxysilane, N-cyclohexyl-γ-aminopropyltrimethoxysilane, N-cyclohexyl-γ-aminopropyltriethoxysilane, γ- ( Amino group-containing alkoxysilanes such as 2-aminoethyl) -aminopropyltrimethoxysilane, γ- (2-aminoethyl) -aminopropylmethyldimethoxysilane, and γ-anilinopropyltrimethoxysilane are also part of the neutralizing agent. Can be used together.

  The aqueous dispersion (B) obtained as described above preferably has a solid content of 0.5 to 50% by mass, based on 100% by mass of the solid content of the aqueous resin composition (A), and 0.5% by mass. When it is less than%, the hydrophilicity of the resulting coating film surface is low and the contact angle with pure water is high, so that the stain resistance tends to be insufficient. On the other hand, if it exceeds 50% by mass, the amount of water elution from the surface of the coating film increases, which may cause the coating film to become brittle and glossy.

  The aqueous coating composition containing the aqueous resin composition (A) and the aqueous dispersion (B) obtained as described above was coated on a glass substrate and dried at a temperature of 10 ° C to 200 ° C for 2 minutes to 10 days. Contamination resistance of the coating film is that the contact angle with the pure water of the coating film surface measured with a static surface contact angle meter CA-X type (manufactured by Kyowa Interface Science Co., Ltd.) is 60 ° or less. It is preferable that it is excellent, and more preferably 40 ° or less.

  The water-based coating composition of the present invention is preferably used for water-based paints used for building interior materials and exterior materials. When used as a paint, only an aqueous coating composition can be used as a clear paint, but commonly used color pigments such as bengara, carbon black, titanium oxide, calcium carbonate, barium carbonate, talc, Body pigments such as clay, mica, alumina, alum, white clay, magnesium hydroxide, magnesium oxide, diatomaceous earth, etc.Furthermore, titanium oxide having photocatalytic activity, frying pontite having anti-staining / adsorption function, activated zinc white, magnesium silicate It is also possible to add functional pigments such as In order to impart various functions as a paint, a thickener, a dispersant, an anti-settling agent, an antifungal agent, an antiseptic, an ultraviolet absorber, a light stabilizer, and the like may be added as appropriate.

  The aqueous coating composition thus obtained can be applied to various inorganic materials, metal materials, wood materials, plastic materials, etc., and is excellent in coating by natural drying or forced drying at a temperature of 50 ° C. or higher. Can be formed. In addition, during film formation, an organic solvent (film forming aid) such as ethylene glycol monobutyl ether or 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate is arbitrarily used for the purpose of lowering the film formation temperature. It is also possible to add to.

  By using the aqueous coating composition of the present invention, it is possible to provide a coating having a coating film that has good stain resistance over a long period of time and excellent water resistance.

  Hereinafter, the present invention will be described using examples, but the present invention is not limited to the following examples. In the examples and comparative examples, “parts” and “%” represent “parts by mass” and “% by mass”, respectively, unless otherwise specified.

(Production Example of Aqueous Resin Composition A1)
In a reactor equipped with a stirrer, a thermometer, a cooling pipe and a dropping device, 210 parts of ion-exchanged water, (α-sulfonato-ω- (1- (allyloxymethyl-alkyloxypolyoxyethylene ammonium salt; ethylene oxide (Average number of moles added: 10 moles) (trade name: Aqualon KH-10, reactive anion emulsifier, manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Warm up.

  Next, 1.2 parts of potassium persulfate (polymerization initiator) was added, 240 parts of methyl methacrylate, 123 parts of butyl acrylate, 130 parts of cyclohexyl acrylate, γ-methacryloxypropyltrimethoxysilane (trade name: KBM503, Shin-Etsu) 2 parts of Chemical Co., Ltd., 5 parts of methacrylic acid, 5 parts of Aqualon KH-10 and 300 parts of water were emulsified and stirred with a disper and added dropwise over 4 hours. After completion of the dropping, the mixture is aged while continuing stirring at 80 ° C. for 1 hour, cooled to 40 ° C., adjusted to pH 9.0 with 50% dimethylethanolamine, and dispersed with emulsion particles having a uniform structure. A1 was obtained.

(Production Example of Aqueous Resin Composition A2)
In a reactor equipped with a stirrer, a thermometer, a cooling pipe and a dropping device, 210 parts of ion exchange water, polyoxyethylene polycyclic phenyl ether sulfate ammonium salt (trade name: New Coal 707SF, non-reactive anionic emulsifier, 5 parts of Nippon Emulsifier Co., Ltd.) and 10 parts of polyoxyethylene lauryl ether (trade name: ET-160, non-reactive nonionic emulsifier, Daiichi Kogyo Seiyaku Co., Ltd.) are charged, and the inside of the reactor is filled with nitrogen. While replacing, the temperature was raised to 80 ° C.

  Subsequently, 1.2 parts of potassium persulfate (polymerization initiator) is added, and an emulsified mixed liquid composed of 218 parts of methyl methacrylate, 25 parts of 2-ethylhexyl acrylate, 4 parts of methacrylic acid, 10 parts of New Coal 707SF, and 120 parts of water is prepared. It was dripped over 2 hours. Subsequently, an emulsified mixed solution composed of 75 parts of methyl methacrylate, 165 parts of 2-ethylhexyl acrylate, 10 parts of diacetone acrylamide, 5 parts of methacrylic acid, 10 parts of New Coal 707SF, and 120 parts of deionized water was added dropwise over 2 hours. After completion of the dropwise addition, the mixture was aged while continuing stirring at 80 ° C. for 2 hours, cooled to 40 ° C., adjusted to pH 9.0 with 50% dimethylethanolamine, added with 5 parts of adipic acid dihydrazide and further stirred for 30 minutes. It was made to melt | dissolve and aqueous resin composition A2 in which the heterophasic structure emulsion particle | grains by the multistage emulsion polymerization method were disperse | distributed was obtained.

(Production Example of Aqueous Resin Composition A3)
In a reactor equipped with a stirrer, a thermometer, a condenser, and a dropping device, 100 parts of isopropanol was charged, and the temperature was raised to 80 ° C. while replacing with nitrogen. Next, 3 parts of azobisisobutyronitrile (polymerization initiator) was added, and a mixed solution consisting of 130 parts of methyl methacrylate, 85 parts of butyl acrylate, 75 parts of cyclohexyl acrylate and 50 parts of acrylic acid was added dropwise over 4 hours. did. After completion of the dropwise addition, the mixture was aged while continuing stirring at 80 ° C. for 4 hours. After cooling to 50 ° C., a mixture of N, N-dimethylethanolamine and deionized water was added to adjust the pH to 8. Next, after removing the solvent under reduced pressure [1.3 × 10 ⁴ Pa (100 torr)] using a reactor equipped with a reflux condenser and a stirrer, the solid content was adjusted to 35% with water. Dilution adjustment was performed to obtain a water-soluble resin having a weight average molecular weight of 85,000, which was designated as an aqueous resin composition A3. Molecular weight was measured using HLC-8020GPC manufactured by Tosoh Corporation, TSKgel G2000H was used as a measurement column, and polystyrene standard was used for preparing a calibration curve.

(Production Example of Aqueous Resin Composition A4)
In a reactor equipped with a stirrer, a thermometer, a cooling pipe, and a dropping device, 170 parts of isopropanol was charged and heated to 80 ° C. while being replaced with nitrogen. Next, 3 parts of azobisisobutyronitrile (polymerization initiator) is added, and from 148 parts of methyl methacrylate, 90 parts of 2-ethylhexyl acrylate, 80 parts of cyclohexyl acrylate, 5 parts of hydroxyethyl methacrylate and 17 parts of acrylic acid. The resulting mixture was added dropwise over 4 hours. After completion of the dropwise addition, the mixture was aged while continuing stirring at 80 ° C. for 4 hours. After cooling to 50 ° C., 10 parts of N, N-dimethylethanolamine and 490 parts of deionized water were added. Next, after removing the solvent under reduced pressure [1.3 × 10 ⁴ Pa (100 torr)] using a reactor equipped with a reflux condenser and a stirrer, the solid content was adjusted to 35% with water. Dilution adjustment was performed and the aqueous resin composition A4 obtained by the phase change method was obtained.

(Production Example of Aqueous Dispersion B1)
In a reactor equipped with a stirrer, a thermometer, a cooling pipe and a dropping device, water-dispersed spherical colloidal silica (trade name: Snowtex S, manufactured by Nissan Chemical Industries, Ltd., solid content 30%, average particle size 8 ˜11 nm, Na stable type) 500 parts and 350 parts of deionized water were charged, and the temperature inside the reactor was increased to 80 ° C. while being replaced with nitrogen. Next, 2 parts of potassium persulfate was added, and a mixed solution of 210 parts of methyl methacrylate and 90 parts of 2-ethylhexyl acrylate which had been stirred and mixed in a separate container in advance was continuously added dropwise over 4 hours. After completion of the dropwise addition, the mixture was aged while continuing stirring at 80 ° C. for 2 hours. After cooling to room temperature, an aqueous ammonia solution was added to adjust the pH to 9 to 10 to obtain an aqueous dispersion B1. The water-dispersed colloidal silica (solid content) was 50 parts by mass with respect to 100 parts by mass of the α, β-ethylenically unsaturated monomer in the aqueous dispersion B1.

(Production Example of Aqueous Dispersion B2)
In a reactor equipped with a stirrer, a thermometer, a cooling pipe and a dripping device, water-dispersed spherical colloidal silica (trade name: Snowtex 20L, manufactured by Nissan Chemical Industries, Ltd., solid content 20%, average particle size 40 ˜50 nm, Na stable type) was charged, and the temperature inside the reactor was increased to 80 ° C. while being replaced with nitrogen. Next, 1.5 parts of potassium persulfate was added, and a mixed solution of 55 parts of methyl methacrylate, 23 parts of butyl acrylate and 1.5 parts of diethylaminoethyl methacrylate, which had been stirred and mixed in a separate container in advance over 4 hours. And continuously dropped. After completion of the dropwise addition, the mixture was aged while continuing stirring at 80 ° C. for 2 hours. After cooling to room temperature, an aqueous ammonia solution was added to adjust the pH to 9 to 10 to obtain an aqueous dispersion B2. The water-dispersed colloidal silica (solid content) was 214 parts by mass with respect to 100 parts by mass of the α, β-ethylenically unsaturated monomer in the aqueous dispersion B2.

(Production Example of Aqueous Dispersion B3)
In a reactor equipped with a stirrer, a thermometer, a cooling tube and a dropping device, water-dispersed chain colloidal silica (trade name: Snowtex PS-S, manufactured by Nissan Chemical Industries, Ltd., solid content 20%, average 790 parts of particles having a particle diameter of 10 to 18 nm bonded to 80 to 120 nm, Na stable type) were charged, and the temperature inside the reactor was increased to 80 ° C. while being replaced with nitrogen. Next, 1.5 parts of potassium persulfate was added, and 28 parts of styrene, 50 parts of methyl methacrylate, 32 parts of butyl acrylate, 8 parts of 4-vinylpyridine, 40 parts of cyclohexyl methacrylate, which had been stirred and mixed in a separate container in advance. The mixed solution was continuously added dropwise over 4 hours. After completion of the dropwise addition, the mixture was aged while continuing to stir at 80 ° C. for 2 hours. After cooling to room temperature, an aqueous ammonia solution was added to adjust the pH to 9 to 10 to obtain an aqueous dispersion B3. The water-dispersed colloidal silica (solid content) was 105 parts by mass with respect to 100 parts by mass of the α, β-ethylenically unsaturated monomer in the aqueous dispersion B3.

(Production Example of Aqueous Dispersion B4)
In a reactor equipped with a stirrer, a thermometer, a cooling pipe and a dropping device, water-dispersed spherical colloidal silica (trade name: Snowtex 20, manufactured by Nissan Chemical Industries, Ltd., solid content 20%, average particle size 10 ˜20 nm, Na stable type) 45 parts, Aqualon KH-10 6 parts, deionized water 500 parts were charged, and the temperature inside the reactor was increased to 80 ° C. while being replaced with nitrogen. Next, 2 parts of potassium persulfate was added, and a mixed solution of 45 parts of styrene, 230 parts of methyl methacrylate, 120 parts of 2-ethylhexyl acrylate, and 8 parts of methacrylic acid previously stirred and mixed in a separate container over 4 hours. And continuously dropped. After completion of the dropwise addition, the mixture was aged while continuing stirring at 80 ° C. for 2 hours. After cooling to room temperature, an aqueous ammonia solution was added to adjust the pH to 9 to 10 to obtain an aqueous dispersion B4. The water-dispersed colloidal silica (solid content) was 2 parts by mass with respect to 100 parts by mass of the α, β-ethylenically unsaturated monomer in the aqueous dispersion B4.

(Production Example of Aqueous Dispersion B5)
In a reactor equipped with a stirrer, a thermometer, a cooling pipe and a dropping device, water-dispersed spherical colloidal silica (trade name: Snowtex MP-2040, manufactured by Nissan Chemical Industries, Ltd., solid content 40%, average particle (Particle diameter 200 nm, Na salt type) 400 parts and deionized water 400 parts were charged, and the temperature inside the reactor was increased to 80 ° C. while being replaced with nitrogen. Next, 2 parts of potassium persulfate was added, and a mixed solution of 210 parts of methyl methacrylate and 90 parts of 2-ethylhexyl acrylate which had been stirred and mixed in a separate container in advance was continuously added dropwise over 4 hours. After completion of the dropwise addition, the mixture was aged while continuing stirring at 80 ° C. for 2 hours. After cooling to room temperature, an aqueous ammonia solution was added to adjust the pH to 9 to 10 to obtain an aqueous dispersion B5. The water-dispersed colloidal silica (solid content) was 53 parts by mass with respect to 100 parts by mass of the α, β-ethylenically unsaturated monomer in the aqueous dispersion B5.

(Production Example of Aqueous Dispersion B6)
In a reactor equipped with a stirrer, a thermometer, a cooling pipe, and a dropping device, 800 parts of water-dispersed spherical colloidal silica (trade name: Snowtex S) was charged, and the inside of the reactor was replaced with nitrogen. The temperature was raised and maintained. Next, 1.5 parts of potassium persulfate was added, and a mixed solution of 39 parts of methyl methacrylate, 15 parts of 2-ethylhexyl acrylate, and 6 parts of diethylaminoethyl methacrylate was previously stirred and mixed in a separate container over 4 hours. And continuously dropped. After completion of the dropwise addition, the mixture was aged while continuing stirring at 80 ° C. for 2 hours. After cooling to room temperature, an aqueous ammonia solution was added to adjust the pH to 9 to 10 to obtain an aqueous dispersion B6. The water-dispersed colloidal silica (solid content) was 400 parts by mass with respect to 100 parts by mass of the α, β-ethylenically unsaturated monomer in the aqueous dispersion B6.

(Production Example of Aqueous Dispersion B7)
In a reactor equipped with a stirrer, a thermometer, a cooling pipe and a dropping device, 500 parts of water-dispersed spherical colloidal silica (trade name: Snowtex S), polyethylene glycol (trade name: PEG # 200, manufactured by NOF Corporation, (Molecular weight 200 g / mol) 15 parts and deionized water 350 parts were charged, and the temperature inside the reactor was raised to 80 ° C. while being replaced with nitrogen. Next, 2 parts of potassium persulfate was added, and a mixed solution of 210 parts of methyl methacrylate and 90 parts of 2-ethylhexyl acrylate which had been stirred and mixed in a separate container in advance was continuously added dropwise over 4 hours. After completion of the dropwise addition, the mixture was aged while continuing stirring at 80 ° C. for 2 hours. After cooling to room temperature, an aqueous ammonia solution was added to adjust the pH to 9 to 10 to obtain an aqueous dispersion B7. The water-dispersed colloidal silica (solid content) was 50 parts by mass with respect to 100 parts by mass of the α, β-ethylenically unsaturated monomer in the aqueous dispersion B7.

(Examples 1-11 and Comparative Examples 1-5)
Formulated as shown in Table 1, 12 parts of deionized water, 20 parts of titanium oxide (trade name: Taipei CR-90, manufactured by Ishihara Sangyo Co., Ltd.) as a pigment, and a nonionic surfactant (as an additive) Product name: Disperbyk-190, manufactured by Big Chemie Japan Co., Ltd. (0.2 parts), urethane thickener (product name: Primal RM-8W, manufactured by Rohm and Haas Co., Ltd.), 2 parts, silicone Each paint was prepared by adding 0.4 part of a system antifoaming agent (trade name: SN deformer 1312, manufactured by San Nopco Co., Ltd.) and 2 parts of ethylene glycol, and various performance evaluations were performed as follows.

<Contact angle>
Each test paint to which an appropriate amount of film forming aid was added was applied to a glass plate with a 6 mil applicator, dried at 60 ° C. for 2 hours, and then dried at room temperature for 1 day. The static contact angle with pure water was measured using a FACE contact angle meter CA-X type manufactured by Kyowa Interface Science, and the results are shown in Table 1.

<Water resistance>
Each test paint to which an appropriate amount of film-forming aid was added was coated on a glass plate with a 6 mil applicator, dried at 50 ° C. for 6 hours, and then cured at room temperature for one day. Thereafter, the test plate was immersed in water at 23 ° C. for 1 week, and the degree of whitening of the coating film after drying was visually determined.

[Evaluation criteria]
A: There is no discoloration of the coating film.
○: The coating film has almost no discoloration or is slightly bluish and transparent.
Δ: The coating film is locally whitened.
X: The coating film is whitened as a whole.

<Hot water whitening resistance>
Each test paint to which an appropriate amount of film forming aid was added was applied on a blackboard with a 6 mil applicator, dried at 50 ° C. for 6 hours, and then cured at room temperature for one day. Thereafter, the test plate was immersed in warm water at 60 ° C. for 24 hours, and the degree of whitening of the coating film after drying was visually determined.

[Evaluation criteria]
A: There is no discoloration of the coating film.
○: The coating film has no discoloration or is slightly bluish and transparent.
Δ: The coating film is locally whitened.
X: The coating film is whitened as a whole.

<Elution properties>
Each test paint was applied to a polytetrafluoroethylene (PTFE) plate with a 6 mil applicator, dried at 70 ° C. for 2 hours, and then dried at room temperature for 1 day. The produced film was peeled off, cut into a 10 cm × 10 cm square, measured for the weight of the film, and then immersed in ion exchange water at 23 ° C. for 24 hours. The taken-out membrane was dried under reduced pressure at 23 ° C., and the elution rate of the coating film into water was calculated according to the following general formula;
Elution rate (%) = {1− (absolute dry weight after immersion) / (absolute dry weight before immersion)} × 100

[Evaluation criteria]
A: Less than 1% elution rate (There is no deterioration of the coating film and the state at the start of the test is maintained)
○: Elution rate of 1% or more and less than 2% (the coating film is hardly deteriorated and the gloss is maintained)
Δ: Elution rate of 2% or more and less than 5% (the coating film surface is washed away slightly and the gloss is partially reduced)
X: Elution rate of 5% or more (the surface of the coating film becomes brittle and the gloss decreases overall)
<Rain-stain stain resistance>
A slate plate coated with a white paint (dimensions 10 cm × 30 cm × thickness 5 mm) was spray-coated with the coating materials of Examples 1 to 11 and Comparative Examples 1 to 5 appropriately added with a film forming aid, and 60 ° C. And dried for 2 hours. After this was cured for 10 days, the rain on the roof covered the roof with a roof inclined by 10 degrees with respect to the horizontal plane and a groove with a length of 30 mm and a depth of 3 mm carved at a pitch of 3 mm. Mounted vertically to the south so as to flow down on the surface, and exposed for 1 month, 6 months, or 12 months in that state, the appearance of the coating film was compared with an untested coating film, and the contamination state was visually observed. . The results are shown in Table 1.

[Evaluation criteria]
(Double-circle): Dirt has not adhered at all and is maintaining the state equivalent to the time of a test start.
○: Although there is slight dirt, almost no rain streak is confirmed.
(Triangle | delta): There exists a local stain | pollution | contamination and a rain stripe is confirmed slightly.
X: There is considerable dirt on the entire surface, and rain streaks are confirmed firmly.

<Storage stability>
Each coating material of Examples 1 to 11 and Comparative Examples 1 to 5 was put in a 100 ml glass sample bottle, stored in a 50 ° C. constant temperature room for one month in a sealed state, and the state was evaluated as follows.

[Evaluation criteria]
○: Same state as before the test, no change.
Δ: Precipitates are not visually confirmed, but there is a difference in appearance when painted.
X: Precipitation was confirmed visually.

  Each coating material containing the aqueous dispersion (B) shown in the examples contains colloidal silica fixed to the emulsion particles, so that the contact angle with the pure water of the coating film becomes low, and the coating film surface becomes hydrophilic. Water wettability was improved, and rainwater penetrated the interface between the coating film and the pollutant to wash away the pollutant.

  Comparative Example 1 is a general emulsion paint, and since the contact angle with pure water was high from the beginning, the rain-stain stain resistance deteriorated. In Comparative Example 2, since the emulsion particles and colloidal silica exist separately, the durability of the rain-stain stain resistance is poor, and the water resistance and warm water whitening resistance are also deteriorated. In Comparative Example 3, because the hydrolyzable silane reacted with time, the rain streak stain resistance was improved, but the storage stability was lowered. In Comparative Example 4, since the average particle size of colloidal silica as water-dispersed inorganic particles was as large as 200 nm, the particles became large and the storage stability deteriorated. In Comparative Example 5, the amount of water-dispersed colloidal silica in the water-dispersed inorganic particles was as large as 400 parts by weight, so that the amount that was free in the paint increased and the elution rate from the coating film increased.

Claims (12)

(A) an aqueous resin composition, and
(B) One or two or more α, β-ethylenically unsaturated monomers 100 using 1 to 300 parts by mass of water-dispersed inorganic particles (solid content) having an average particle size of 4 to 100 nm as an emulsion stabilizer A low-fouling aqueous coating composition comprising an aqueous dispersion obtained by emulsion polymerization of parts by mass.   The low-fouling aqueous coating composition according to claim 1, wherein no anionic, nonionic or cationic surfactant is used as an emulsifier during emulsion polymerization of the aqueous dispersion (B).   3. In the emulsion polymerization of the aqueous dispersion (B), polyvinyl alcohol, hydroxyalkyl cellulose, polyalkylene glycol, water-soluble resin, and polymer surfactant are not used at all as a colloid stabilizer. The low fouling aqueous coating composition as described.   The low contamination according to any one of claims 1 to 3, wherein the solid content of the aqueous dispersion (B) is 0.5 to 50% by mass with respect to 100% by mass of the solid content of the aqueous resin composition (A). Water-based coating composition.   The aqueous resin composition (A) is an aqueous resin composition containing one or both of an emulsion having a uniform structure and a heterophasic structure emulsion obtained by a multistage emulsion polymerization method. Low contamination aqueous coating composition.   The aqueous resin composition (A) contains a water-soluble resin composed of polyvinyl alcohol, polyamide, polyacrylic acid, polyacrylate, or a copolymer thereof, and has a weight average molecular weight of 5,000 to 100. The low-fouling aqueous coating composition according to any one of claims 1 to 4.   The low-fouling aqueous coating composition according to any one of claims 1 to 4, wherein the aqueous resin composition (A) is an aqueous resin composition obtained by a phase inversion and forced emulsification method.   The water-dispersed inorganic particles are water-dispersed colloidal silica, and the water-dispersed colloidal silica has one or both of a spherical shape and a chain shape. Coating composition.   The α, β-ethylenically unsaturated monomer is a carboxyl group-containing monomer, an amino group-containing monomer, an amide group-containing monomer, a hydroxyl group-containing monomer, or an alkoxysilyl group-containing monomer. The low-contamination aqueous coating composition according to any one of claims 1 to 8, comprising at least one member selected from the group. Furthermore, the low pollution water-based coating composition in any one of Claims 1-9 containing (C) hydrolysable silane represented by the following general formula (a).
_{^{(R 1) n -Si- (R}} 2) 4-n (a)
(In the formula (a), n is an integer of 0 to 3, ^{R 1} is a hydrogen atom, an aliphatic hydrocarbon group of 1 to 16 carbon atoms, an aryl group having 5 to 10 carbon atoms, 5-6 carbon atoms It is selected from a cycloalkyl group, a vinyl group, an alkyl acrylate group having 1 to 10 carbon atoms, or an alkyl methacrylate group having 1 to 10 carbon atoms, and n R ^{1 s} may be the same or different. R ² is selected from an alkoxy group having 1 to 8 carbon atoms, an acetoxy group or a hydroxyl group. (4-n) R ^{2 s} may be the same or different.   The contact angle with the pure water of the coating-film surface formed by apply | coating and drying the said low-contamination aqueous coating composition is 60 degrees or less, The low-contamination property in any one of Claims 1-10 Aqueous coating composition.   A coating comprising a coating formed by applying the low-fouling aqueous coating composition according to any one of claims 1 to 11 onto a substrate.