JP2008189884A - Aqueous coating material and coated article - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an aqueous coating material having excellent storage stability, resistance to contamination, transparency, weather resistance and freeze damage resistance, and to provide a coated article having a coated film excellent in resistance to contamination, transparency, weather resistance and freeze damage resistance. <P>SOLUTION: This aqueous coating material comprises a copolymer, a silica particle, at least one anionic surfactant selected from the group consisting of a sulfuric ester salt of a polyoxyalkylene aryl ether, a sulfuric ester salt of a polyoxyalkylene alkylaryl ether, a formalin condensate of a sulfuric ester salt of a polyoxyalkylene aryl ether and a formalin condensate of a sulfuric ester salt of a polyoxyalkylene alkylaryl ether, and a nonionic surfactant, wherein an amount of the silica particle is 0.5-20 parts by mass based on the copolymer of 100 parts by mass, and an absolute value of zeta-potential is ≥33 mV and ≤58 mV. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an aqueous coating material and a coated article having a coating film obtained from the aqueous coating material.

  In recent years, in the paint field, conversion from organic solvent-based paints to water-based paints (water-based coating materials) has been attempted from the viewpoints of environmental protection and health and safety. However, the coating film obtained from the water-based coating material has low coating film performance such as weather resistance, water resistance, frost damage resistance, and stain resistance, particularly stain resistance compared to the solvent system, and there are problems to be solved. There are many current situations.

  Development of water-based coating materials and development of coating film laminating methods for the purpose of solving these problems have been carried out in various ways. For example, as a resin for an aqueous coating material, an emulsion of an acrylic resin by emulsion polymerization has been attracting attention because it has a characteristic that the weather resistance of the resulting coating film is relatively good. In addition, the water-based emulsion for undercoat, water-based emulsion for intermediate-coat, and water-based emulsion for top-coat are each given performance, and these water-based emulsions are sequentially layered to show the coating properties such as stain resistance as a whole. The idea to do is made.

As a method for improving the stain resistance of the coating film, for example, the following method is known.
(I) A method of increasing the hardness of the coating film (increasing the glass transition temperature (Tg) of the resin).
(Ii) A method of imparting a self-cleaning action of hydrophilizing the coating surface and washing away contaminants with rainwater.
(Iii) A method of controlling the chargeability of the coating film to suppress the adhesion of dirt due to static electricity.

However, the method (i) has a problem that the film-forming property is lowered, the coating film is cracked in winter, and the frost damage resistance is problematic. In addition, it is difficult to greatly improve the stain resistance of the coating film.
Examples of the method (ii) include a method using a resin containing a monomer unit having hydrophilicity, and adding a surfactant or the like. However, a resin containing a monomer unit having hydrophilicity has a problem of low weather resistance. Moreover, when surfactant etc. are added, the water resistance of a coating film falls and there exists a problem in sustaining the effect of stain resistance.
In the method (iii), the addition of the antistatic agent has an adverse effect on the weather resistance and water resistance of the coating film, and there is a problem in the sustainability of the effect.

As an aqueous coating material for solving these problems, an aqueous coating material containing an inorganic substance is known. As the aqueous coating material, for example, the following aqueous coating material has been proposed.
(1) A coating composition in which colloidal silica is contained in an aqueous emulsion containing a copolymer of vinyl silane and an acrylic monomer (Patent Document 1).

  The coating film comprising the coating composition (1) is said to be excellent in heat resistance, water resistance and adhesion. However, the coating composition of (1) requires a large amount of colloidal silica having a solid content of 500 to 20000 parts by mass with respect to 100 parts by mass of the solid content of the aqueous emulsion. When a large amount of colloidal silica is used, there are problems that transparency of the coating film, weather resistance, storage stability of the coating composition, and coating workability are poor.

On the other hand, as an aqueous coating material using a relatively small amount of colloidal silica, for example, the following aqueous coating material has been proposed.
(2) A flame retardant containing 100 parts by mass of a polyorganosiloxane graft copolymer emulsion in which an unsaturated vinyl monomer is 10 to 90 parts by mass graft-copolymerized with respect to polyorganosiloxane, and 1 to 50 parts by mass of colloidal silica. Coating material (Patent Document 2).
(3) An aqueous coating composition containing 100 parts by weight of a polyorganosiloxane-based graft copolymer emulsion and 1 to 300 parts by weight of colloidal silica (Patent Document 3).

  The coating film made of the flame retardant coating material (2) is said to be excellent in flame retardancy, extensibility, adhesiveness, temperature sensitive characteristics, moisture permeability, and stain resistance. However, the coating material (2) contains 52 parts by mass or more of the polyorganosiloxane component in 100 parts by mass of the solid content of the polyorganosiloxane-based graft block copolymer emulsion, and contains a large amount of water-repellent silicone component. Yes. For this reason, the hydrophilicity of the coating film becomes insufficient and the stain resistance is low. There are also problems in terms of storage stability of the coating material, transparency of the coating film, and hardness.

  The aqueous coating composition (3) is excellent in storage stability, and the coating film is said to be excellent in hardness, water resistance, and stain resistance. The coating film comprising the aqueous coating composition of (3) has significantly improved contamination resistance compared to the coating film comprising the coating material of (2), but further reduced contamination by making the coating film hydrophilic. Is required. Also, the storage stability of the aqueous coating composition is insufficient.

For example, the following method has been proposed as a method for suppressing the adhesion of dirt due to static electricity.
(4) In the surface coating of cementitious materials, it becomes a multi-layered structure of undercoat, intermediate coat, and topcoat, and silicate or silica sol is blended in all of them to prevent the accumulation of static electricity in the laminated coating, thereby preventing the adhesion of static electricity. A method of preventing and imparting stain resistance to the coating film (Patent Documents 4, 5, etc.).

  However, in the method (4), if any one of the undercoating, intermediate coating, and topcoating is a resin-only coating film, there is a problem that static electricity stays and stains adhere to the coating film.

As other aqueous coating materials, for example, the following aqueous coating materials have been proposed.
(5) A coating component containing a polymer, 0.5 to 20 parts by mass of colloidal silica having an average particle diameter of 60 nm or less, an anionic surfactant having at least one specific structure, and a nonionic surfactant A water-based coating material containing Patent Document 6 (Patent Document 6).

The coating film made of the aqueous coating material (5) is excellent in stain resistance, transparency, weather resistance, and coating film elongation, but the storage stability of the aqueous coating material has not reached a sufficient level.
JP-B-1-41180 JP-A-4-23857 JP-A-9-165554 Japanese Patent Publication No.53-34141 JP-A-5-96234 International Publication No. 2005/075583 Pamphlet

  An object of the present invention is to provide an aqueous coating material capable of forming a coating film having excellent storage stability and stain resistance, transparency, weather resistance and frost damage resistance, and stain resistance, transparency, weather resistance and frost damage resistance. An object of the present invention is to provide a coated article having a coating film having excellent properties.

  The aqueous coating material of the present invention comprises a formalin condensation of a copolymer, silica particles, polyoxyalkylene aryl ether sulfate ester salt, polyoxyalkylene alkyl aryl ether sulfate ester salt, and polyoxyalkylene aryl ether sulfate ester salt. And an aqueous coating material containing at least one anionic surfactant selected from the group consisting of a formalin condensate of a sulfate of polyoxyalkylene alkylaryl ether and a nonionic surfactant, The amount of silica particles is 0.5 to 20 parts by mass with respect to 100 parts by mass of the copolymer, and the zeta potential absolute value of the aqueous coating material is from 33 mV to 58 mV.

The average particle diameter of the silica particles is preferably 1 to 60 nm.
The copolymer preferably contains 0.1 to 20 parts by mass of a unit derived from a hydrolyzable silyl group-containing radical polymerizable monomer with respect to 100 parts by mass of the copolymer.
The coated article of the present invention has a coating film obtained from the aqueous coating material of the present invention.

The aqueous coating material of the present invention is excellent in storage stability. Moreover, according to the aqueous coating material of this invention, the coating film which is excellent in stain resistance, transparency, a weather resistance, and frost damage resistance can be formed.
The coated product of the present invention is excellent in stain resistance, transparency, weather resistance, and frost damage resistance of the coating film.

  In this specification, (meth) acrylate means an acrylate or a methacrylate.

<Water-based coating material>
The aqueous coating material of the present invention is an aqueous coating composition containing water, a copolymer, silica particles, a specific anionic surfactant, and a nonionic surfactant.
The solid content concentration of the aqueous coating material is usually 10 to 80% by mass.

(Zeta potential)
The absolute value of the zeta potential of the aqueous coating material of the present invention is 33 mV or more and 58 mV or less, more preferably 34 mV or more, and further preferably 35 mV or more. If the absolute value of the zeta potential of the aqueous coating material is 33 mV or more, the repulsive force between particles acting between the copolymer and silica particles contained in the aqueous coating material is increased, and the storage stability is improved. When the absolute value of the zeta potential of the aqueous coating material is 58 mV or less, the stain resistance (hydrophilicity, conductivity) of the coating film can be obtained.

The zeta potential of the aqueous coating material can be measured using DT-1200 (manufactured by Dispersion Technology). Zeta advanced obtained by the measurement is taken as a measured value of the zeta potential.
The solid content of the aqueous coating material required for the measurement is measured according to JIS K 5407-4-2001. The particle diameter of the aqueous coating material is measured using an apparatus utilizing a dynamic light scattering method or the like. The true specific gravity of the aqueous coating material is calculated by measuring the bulk specific gravity of the aqueous coating material and using the software attached to DT-1200 from the specific gravity bottle volume obtained in the measurement process and the sample mass in the specific gravity bottle. To do.

(Copolymer)
The copolymer is a film-forming component and is a component that imparts film-forming properties, weather resistance, water resistance, frost damage resistance, and the like to the coating film.

  Examples of the copolymer include polyester resins, polyurethane resins, acrylic resins, acrylic silicon resins, and fluorine resins. Of these, acrylic resins and acrylic silicon resins are preferable, and acrylic silicon resins are more preferable from the viewpoint of stain resistance, weather resistance, water resistance, and frost damage resistance of the coating film.

  Examples of the radical polymerizable monomer that constitutes the acrylic resin and the acrylic silicon resin include the following monomers. The radical polymerizable monomer is not limited to any monomer as long as it is capable of radical polymerization.

Vinylsilanes: vinylmethyldimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldichlorosilane, vinyltrichlorosilane and the like.
Acrylyloxyalkylsilanes: γ-acryloyloxyethylmethyldimethoxysilane, γ-acryloyloxyethyltrimethoxysilane, γ-acryloyloxyethyltriethoxysilane, γ-acryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropyltrimethoxysilane Γ-acryloyloxypropyltriethoxysilane, γ-acryloyloxyethylmethyldichlorosilane, γ-acryloyloxyethyltrichlorosilane, γ-acryloyloxypropylmethyldichlorosilane, γ-acryloyloxypropyltrichlorosilane, and the like.
Methacryloyloxyalkylsilanes: γ-methacryloyloxyethylmethyldimethoxysilane, γ-methacryloyloxyethyltrimethoxysilane, γ-methacryloyloxyethyltriethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane Γ-methacryloyloxypropyltriethoxysilane, γ-methacryloyloxyethylmethyldichlorosilane, γ-methacryloyloxyethyltrichlorosilane, γ-methacryloyloxypropylmethyldichlorosilane, γ-methacryloyloxypropyltrichlorosilane, and the like.

Alkyl (meth) acrylates having an alkyl group having 1 to 18 carbon atoms: methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, i-propyl (meth) acrylate, n-butyl (meth) ) Acrylate, i-butyl (meth) acrylate, sec-butyl (meth) acrylate, t-butyl (meth) acrylate, n-amyl (meth) acrylate, i-amyl (meth) acrylate, n-hexyl (meth) acrylate 2-ethylhexyl (meth) acrylate, n-octyl (meth) acrylate, nonyl (meth) acrylate, decyl (meth) acrylate, dodecyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and the like.
Cycloalkyl (meth) acrylates: cyclohexyl (meth) acrylate, pt-butylcyclohexyl (meth) acrylate, and the like.
Hydroxyl group-containing radical polymerizable monomers: 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, glycerol mono ( (Meth) acrylate and the like.
Polyoxyalkylene group-containing (meth) acrylates: hydroxypolyethylene oxide mono (meth) acrylate, hydroxypolypropyleneoxide mono (meth) acrylate, hydroxy (polyethyleneoxide-polypropyleneoxide) mono (meth) acrylate, hydroxy (polyethyleneoxide-propyleneoxide) ) Mono (meth) acrylate, hydroxy (polyethylene oxide-polytetramethylene oxide) mono (meth) acrylate, hydroxy (polyethylene oxide-tetramethylene oxide) mono (meth) acrylate, hydroxy (polypropylene oxide-polytetramethylene oxide) mono ( (Meth) acrylate, hydroxy (polypropylene oxide-tetramethylene oxide) mono (meth) acrylate Rate, methoxypolyethylene oxide mono (meth) acrylate, lauroxypolyethylene oxide mono (meth) acrylate, stearoxypolyethylene oxide mono (meth) acrylate, allyloxypolyethylene oxide mono (meth) acrylate, nonylphenoxypolyethylene oxide mono (meth) acrylate Nonylphenoxy polypropylene oxide mono (meth) acrylate, octoxy (polyethylene oxide-polypropylene oxide) mono (meth) acrylate, nonylphenoxy (polyethylene oxide-propylene oxide) mono (meth) acrylate, and the like.

Hydroxycycloalkyl (meth) acrylates: p-hydroxycyclohexyl (meth) acrylate and the like.
Lactone-modified hydroxyl group-containing radical polymerizable monomers.
Aminoalkyl (meth) acrylates: 2-aminoethyl (meth) acrylate, 2-dimethylaminoethyl (meth) acrylate, 2-aminopropyl (meth) acrylate, 2-butylaminoethyl (meth) acrylate, and the like.
Amide group-containing polymerizable monomer: (meth) acrylamide, N-methylolacrylamide, N-butoxymethyl (meth) acrylamide and the like.
Multifunctional (meth) acrylates: ethylene glycol di (meth) acrylate, propylene glycol di (meth) acrylate, butylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and the like.
Metal-containing radical polymerizable monomers: zinc diacrylate, zinc dimethacrylate, and the like.
UV-resistant (meth) acrylates: 2- (2′-hydroxy-5 ′-(meth) acryloxyethylphenyl) -2H-benzotriazole, 1- (meth) acryloyl-4-hydroxy-2,2, 6,6-tetramethylpiperidine, 1- (meth) acryloyl-4-methoxy-2,2,6,6-tetramethylpiperidine, 1- (meth) acryloyl-4-amino-4-cyano-2,2, 6,6-tetramethylpiperidine and the like.
Other (meth) acrylic monomers: dimethylaminoethyl (meth) acrylate methyl chloride salt, allyl (meth) acrylate, glycidyl (meth) acrylate, (meth) acrylonitrile, phenyl (meth) acrylate, benzyl (meth) acrylate , Isobornyl (meth) acrylate, tetrahydrofurfuryl (meth) acrylate, methoxyethyl (meth) acrylate, ethoxyethyl (meth) acrylate, and the like.
Carbonyl group-containing monomer based on aldehyde group or keto group: acrolein, diacetone acrylamide, formyl styrene, vinyl methyl ketone, vinyl ethyl ketone, vinyl isobutyl ketone, pivalin aldehyde, diacetone (meth) acrylate, acetonitrile acrylate, acetoacetoxyethyl (Meth) acrylate and the like.

Aromatic vinyl monomers: styrene, methylstyrene, chlorostyrene, methoxystyrene, etc.
Conjugated diene monomers: 1,3-butadiene, isoprene, 2-chloro-1,3-butadiene and the like.
Carboxyl group-containing monomers: (meth) acrylic acid, itaconic acid, fumaric acid, maleic acid, half esters thereof, 2- (meth) acryloxyethylphthalic acid, 2- (meth) acryloxyethylhexahydrophthalic acid etc.
Radical polymerizable monomer: vinyl acetate, vinyl chloride, ethylene, vinyl propionate, etc.
A silicone polymer having a graft crossing agent described later.
Oxirane group-containing radical polymerizable monomer: glycidyl (meth) acrylate and the like.
Self-crosslinking functional group-containing radical polymerizable monomer: alkylol or alkoxy of ethylenically unsaturated amide such as N-methylol (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N-methoxymethyl (meth) acrylamide Alkyl compounds and the like.

  The copolymer preferably contains units derived from a hydrolyzable silyl group-containing radical polymerizable monomer from the viewpoint of stain resistance, weather resistance, and water resistance of the coating film. By containing units derived from hydrolyzable silyl group-containing radical polymerizable monomers, the copolymer and silica particles are easily bound, and the amount of silica particles exposed to the coating surface is improved. Thus, the silica particle layer can be made thick, and the stain resistance, weather resistance, and water resistance can be further improved.

  The content of the unit derived from the hydrolyzable silyl group-containing radical polymerizable monomer is preferably 0.1 to 20 parts by mass, more preferably 0.5 to 18 parts by mass with respect to 100 parts by mass of the copolymer. preferable. When the content of the unit derived from the hydrolyzable silyl group-containing radical polymerizable monomer is 0.1 parts by mass or more, the stain resistance, weather resistance, and water resistance of the coating film are improved. If the content of the unit derived from the hydrolyzable silyl group-containing radical polymerizable monomer is 20 parts by mass or less, the contamination resistance, weather resistance, and water resistance can be reduced without reducing the frost resistance of the coating film. Further improvement can be achieved.

  Examples of the hydrolyzable silyl group-containing radical polymerizable monomer include the aforementioned vinyl silanes, acryloyloxyalkylsilanes, methacryloyloxyalkylsilanes, and the like. Of these, acryloyloxyalkylsilanes and methacryloyloxyalkylsilanes are particularly preferable from the viewpoints of radical polymerization reactivity, stain resistance of the coating film, weather resistance, and water resistance.

  The copolymer is composed of a polymer block (A) having dimethylsiloxane as a repeating unit and a radical polymerizable monomer in order to develop higher stain resistance, weather resistance, water resistance, and frost damage resistance of the coating film. Graft block copolymer comprising a polymer block (B) having a polymer as a repeating unit, and a silicon-containing graft crossover agent unit (C) copolymerized with the polymer block (A) and the polymer block (B) It is preferable that

The polymer block (A) is a so-called polyorganosiloxane obtained by polymerizing the following raw materials.
Dimethyl dialkoxysilanes: dimethyldimethoxysilane, dimethyldiethoxysilane and the like.
Dimethylsiloxane cyclic oligomers: hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, dodecamethylcyclohexasiloxane, tetradecamethylcycloheptasiloxane, dimethyl cyclic (dimethylsiloxane cyclic oligomer 3-7mer Mixture) and the like.
Other: Dimethyldichlorosilane and the like.

As a raw material for the polymer block (A), a dimethylsiloxane cyclic oligomer is most preferable from the viewpoint of performance such as thermal stability of the obtained graft block copolymer and cost.
The mass average molecular weight of the polymer block (A) is preferably 10,000 or more, and more preferably 50,000 or more. When the mass average molecular weight is 10,000 or more, a coating film having sufficient durability can be obtained.

  The content of the polymer block (B) is preferably 50 to 99.7 parts by mass, and more preferably 60 to 99.5 parts by mass with respect to 100 parts by mass of the graft block copolymer. When the content of the polymer block (B) is 50 parts by mass or more, the hardness, strength and stain resistance of the coating film are improved. If content of a polymer block (B) is 99.7 mass parts or less, it exists in the tendency which can suppress the fall of the weather resistance of a coating film, water resistance, and frost damage resistance.

  The silicon-containing graft crossing agent unit (C) is a component that ensures the transparency of the resulting coating film. Examples of the silicon-containing graft crossing agent include the hydrolyzable silyl group-containing radical polymerizable monomer described above. These may be used individually by 1 type and may be used in combination of 2 or more type.

  The content of the silicon-containing graft crossing agent unit (C) (in terms of silicon atoms) is preferably 0.5 to 50 mol%, and preferably 1 to 15 mol, out of a total of 100 mol% of silicon atoms in the graft block copolymer. % Is more preferable. When the content of the silicon-containing graft crossing agent is 0.5 mol% or more, the transparency of the coating film is improved. When the content of the silicon-containing graft crossing agent is 50 mol% or less, the coating film performance is improved. Further, when the content of the silicon-containing graft crossing agent is 1 mol% or more, the transparency of the obtained coating film is extremely good. Further, when the content of the silicon-containing graft crossing agent is 15 mol% or less, the latex stability during emulsion polymerization is good.

  The copolymer preferably contains a unit derived from a carboxyl group-containing monomer from the viewpoint of storage stability of the aqueous coating material, blending stability when a pigment and additives are added to form a paint.

  0.1-10 mass parts is preferable with respect to 100 mass parts of copolymers, and, as for content of the unit derived from a carboxyl group-containing monomer, 0.5-8 mass parts is more preferable. If the content of the unit derived from the carboxyl group-containing monomer is 0.1 parts by mass or more, the storage stability of the aqueous coating material is improved, and when the pigment is added to the aqueous coating material and colored, aggregates are formed. Problems that might occur can be avoided. If the content of the unit derived from the carboxyl group-containing monomer is 10 parts by mass or less, the storage stability and blending stability of the aqueous coating material are further improved without reducing the weather resistance and water resistance of the coating film. Can be made.

  Examples of the carboxyl group-containing monomer include (meth) acrylic acid, itaconic acid, citraconic acid, maleic acid, monomethyl maleate, monobutyl maleate, monomethyl itaconate, monobutyl itaconate, vinylbenzoic acid, monohydroxy oxalate Ethyl (meth) acrylate, tetrahydrophthalic acid monohydroxyethyl (meth) acrylate, tetrahydrophthalic acid monohydroxypropyl (meth) acrylate, 5-methyl-1,2-cyclohexanedicarboxylic acid monohydroxyethyl (meth) acrylate, phthalic acid mono Hydroxyethyl (meth) acrylate, monohydroxypropyl (meth) acrylate phthalate, monohydroxyethyl (meth) acrylate maleate, hydroxypropyl (meth) acrylate maleate DOO, tetrahydrophthalic acid mono-hydroxybutyl (meth) acrylate. These may be used individually by 1 type and may be used in combination of 2 or more type.

  The copolymer is a hydroxyl group-containing radically polymerizable monomer and / or polyoxy, from the viewpoints of blending stability of the aqueous coating material, stain resistance of the coating film, weather resistance, water resistance and adhesion to various substrates. It is preferable to contain a unit derived from an alkylene group-containing radical polymerizable monomer.

  The content of units derived from the hydroxyl group-containing radical polymerizable monomer and the polyoxyalkylene group-containing radical polymerizable monomer is preferably 0.5 to 20 parts by mass with respect to 100 parts by mass of the copolymer, 1-12 mass parts is more preferable. When the content of these monomer units is 0.5 parts by mass or more, the mixing stability of the aqueous coating material, the stain resistance of the coating film, the weather resistance, the water resistance, and the adhesion to various substrates are improved. If the content of these monomer units is 20 parts by mass or less, the blending stability of the water-based coating material, the stain resistance of the coating film, and various base materials are reduced without reducing the weather resistance and water resistance of the coating film. Adhesion can be further improved.

  Examples of the hydroxyl group-containing radical polymerizable monomer include hydroxymethyl (meth) acrylate and 6-hydroxyhexyl (meth) acrylate in addition to the above-mentioned hydroxyl group-containing radical polymerizable monomers.

Examples of the polyoxyalkylene group-containing radical polymerizable monomer include the above-mentioned polyoxyalkylene group-containing radical polymerizable monomers (terminal hydroxy type polyoxyalkylene group-containing radical polymerizable monomer, alkyl group terminal type). Polyoxyalkylene group-containing radical polymerizable monomer).
These may be used individually by 1 type and may be used in combination of 2 or more type.

  The copolymer preferably contains units derived from t-butyl methacrylate and / or cyclohexyl methacrylate from the viewpoint of the weather resistance and water resistance of the coating film.

  The content of units derived from t-butyl methacrylate and cyclohexyl methacrylate is preferably 5 to 70 parts by mass and more preferably 10 to 60 parts by mass with respect to 100 parts by mass of the copolymer. When the content of these monomer units is 5 parts by mass or more, the water resistance and weather resistance of the coating film are improved. When the content of these monomer units is 70 parts by mass or less, the weather resistance and water resistance can be further improved without reducing the frost damage resistance of the coating film.

  The copolymer preferably contains a unit derived from a self-crosslinkable functional group-containing radical polymerizable monomer from the viewpoint of stain resistance, weather resistance, water resistance and adhesion to various substrates of the coating film. . The self-crosslinkable functional group-containing radical polymerizable monomer is chemically stable while the copolymer is dispersed in an aqueous dispersion and stored at room temperature. It means a radically polymerizable monomer having a functional group that causes a reaction between side chain functional groups due to other external factors and generates a chemical bond between the side chain groups.

  The content of the unit derived from the self-crosslinkable functional group-containing radical polymerizable monomer is preferably 0.1 to 15 parts by mass, more preferably 0.5 to 12 parts by mass with respect to 100 parts by mass of the copolymer. preferable. If the content of the unit derived from the self-crosslinkable functional group-containing radical polymerizable monomer is 0.1 part by mass or more, the coating film has stain resistance, weather resistance, water resistance and adhesion to various substrates. improves. If the content of the unit derived from the self-crosslinkable functional group-containing radical polymerizable monomer is 15 parts by mass or less, the stain resistance of the coating film and various kinds of materials can be reduced without deteriorating the water resistance and weather resistance of the coating film. The adhesion to the substrate can be further improved.

  Examples of the self-crosslinkable functional group-containing radical polymerizable monomer include the above-mentioned self-crosslinkable functional group-containing radical polymerizable monomer (oxirane group-containing radical polymerizable monomer, ethylol unsaturated amide alkylol or alkoxy). Alkyl compounds). These may be used individually by 1 type and may be used in combination of 2 or more type.

  It is preferable that a copolymer contains the unit derived from an ultraviolet-ray radically polymerizable monomer from the point of the weather resistance of a coating film.

  0.1-10 mass parts is preferable with respect to 100 mass parts of copolymers, and, as for content of the unit derived from an ultraviolet-resistant radical polymerizable monomer, 0.5-8 mass parts is more preferable. When the content of the unit derived from the UV-resistant radical polymerizable monomer is 0.1 parts by mass or more, the weather resistance of the coating film is improved. If the content of the unit derived from the UV-resistant radical polymerizable monomer is 10 parts by mass or less, the weather resistance of the coating film can be further improved without lowering the polymerization stability.

  Examples of the UV-resistant radical polymerizable monomer include (meth) acrylate having a light stabilizing action and (meth) acrylate having an UV-absorbing component.

  Examples of the (meth) acrylate having a light stabilizing action 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) acryloyloxy-2,2,6,6-tetramethylpiperidine and the like.

Examples of the (meth) acrylate having an ultraviolet absorbing component include 2- [2-hydroxy-5- (meth) acryloyloxyethylphenyl] -2H-benzotriazole, 2- [2-hydroxy-3-t-butyl. -5- (meth) acryloyloxyethylphenyl] -2H-benzotriazole, 2- [2-hydroxy-3-t-amyl-5- (meth) acryloyloxyethylphenyl] -2H-benzotriazole, and the like.
These may be used individually by 1 type and may be used in combination of 2 or more type.

  Monomers mentioned above (hydrolyzable silyl group-containing radical polymerizable monomer, graft crossing agent, carboxyl group-containing monomer, hydroxyl group-containing radical polymerizable monomer, polyoxyalkylene group-containing radical polymerizable monomer Body, t-butyl methacrylate, cyclohexyl methacrylate, self-crosslinkable functional group-containing radical polymerizable monomer, UV-resistant radical polymerizable monomer) may be used in combination of two or more.

  The content of each monomer unit in the copolymer can be measured using various apparatuses. For example, gas chromatograph, pyrolysis gas chromatograph, gas chromatograph mass spectrometer, pyrolysis gas chromatograph mass spectrometer, high speed liquid chromatograph, liquid chromatograph, liquid chromatograph mass spectrometer, Fourier transform infrared spectrophotometer, nuclear magnetic Examples include a resonance apparatus, a fluorescent X-ray apparatus, and an ICP emission analysis apparatus. These may be used individually by 1 type and may be used in combination of 2 or more type. Furthermore, an appropriate pretreatment may be performed when using each device.

(Silica particles)
Silica particles are components that impart hydrophilicity, antistatic properties, hardness, and weather resistance to the coating film. Moreover, it is a component which exhibits sufficient stain resistance by imparting hydrophilicity and electrostatic property to the coating film.

  0.5-20 mass parts is preferable with respect to 100 mass parts of copolymers, and, as for the quantity of a silica particle, 1-18 mass parts is more preferable. When the amount of silica particles is 0.5 parts by mass or more, the stain resistance (hydrophilicity and antistatic property) of the coating film is improved. If the amount of silica particles is 20 parts by mass or less, the contamination resistance (hydrophilicity, antistatic property) of the coating film is improved without reducing the transparency, weather resistance, water resistance, and frost damage resistance of the coating film. To do. Moreover, if the quantity of a silica particle is 20 mass parts or less, whitening of a coating film will be suppressed.

The average particle size of the silica particles is preferably 1 to 60 nm, more preferably less than 40 nm, and even more preferably less than 20 nm. If the average particle diameter of the silica particles is 60 nm or less, the silica particles are likely to float on the surface of the coating film during the formation of the coating film, and the silica particles closely fill the copolymer particle gap in the surface layer of the coating film, In addition, a silica particle layer is formed with a thickness, and the copolymer, silica particles, and silica particles are chemically bonded or physically adsorbed so that they are present on the outermost layer of the coating film, thereby exhibiting sufficient stain resistance. Is done. Moreover, if the average particle diameter of a silica particle is 60 nm or less, the irregular reflection of the light in the surface of a coating film can be suppressed, and it can suppress that a coating film looks white.
The average particle diameter of the silica particles is calculated using an image processing software, and the silica particle diameter is calculated from the TEM observation image of the silica particles by comparing with the length of the scale bar of the TEM observation image to calculate 10 points. To do.

Silica particles may be surface-treated with a silane compound represented by the following general formula (1).
SiR ¹ _{n + 1} (OR ² ) _3-n (1)
(In the formula, R ¹ represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms, R ² represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms that may contain an ether bond, n represents an integer of 0 to 2.)

  Examples of the silane compound represented by the general formula (1) include trimethoxysilane, dimethoxysilane, dimethoxydimethylsilane, methoxytrimethylsilane, triethoxysilane, diethoxymethylsilane, dimethylethoxysilane, phenyltrimethoxysilane, and dimethoxyphenylsilane. , Phenyltriethoxysilane, diethoxyphenylsilane and the like. These may be used alone or in combination of two or more. Of these, trimethoxymethylsilane is particularly preferred.

Examples of the method for surface-treating silica particles with a silane compound include the following methods.
(I) A method in which colloidal silica and a silane compound are added to an aqueous dispersion of a copolymer, and the mixture is stirred in a temperature range from room temperature to 100 ° C. for an arbitrary time.
(Ii) Silica particles surface-treated with a silane compound obtained by stirring colloidal silica and a silane compound in the temperature range of room temperature to 100 ° C. for an arbitrary time are added to the aqueous dispersion of the copolymer. how to.
(Iii) A method in which a silane compound is applied to silica particles unevenly distributed on the outermost layer of the coating film after the coating film has been prepared, and heat-treated at a temperature range of room temperature to 100 ° C. for an arbitrary time.

  1-60 mass parts is preferable with respect to 100 mass parts of silica particles, and, as for the quantity of a silane compound, 5-40 mass parts is more preferable. If the quantity of a silane compound is 1 mass part or more, the weather resistance of a coating film will improve. When the amount of the silane compound is 60 parts by mass or less, the weather resistance of the coating film can be further improved without lowering the storage stability of the aqueous coating material, the stain resistance of the coating film, and the water resistance.

(Surfactant)
The specific anionic surfactant and nonionic surfactant are components that impart stain resistance to the coating film. When the aqueous coating material contains a specific anionic surfactant and a nonionic surfactant, the outermost silica particle layer of the coating film can be thickened, and the hydrophilicity and A coating film having antistatic properties can be obtained.

  Specific anionic surfactants include polyoxyalkylene aryl ether sulfates, polyoxyalkylene alkyl aryl ether sulfates, polyoxyalkylene aryl ether sulfate formalin condensates, and polyoxyalkylene alkyl aryls. It is at least one selected from the group consisting of formalin condensates of ether sulfates.

  0.1-10 mass parts is preferable with respect to 100 mass parts of copolymers, and, as for the quantity of an anionic surfactant, 0.5-8 mass parts is more preferable. If the amount of the anionic surfactant is 0.1 parts by mass or more, the stain resistance of the coating film, the stability during preparation of the aqueous coating material, and the storage stability of the aqueous coating material are improved. When emulsion polymerization is performed in the presence, the stability during polymerization is also improved. If the amount of the anionic surfactant is 10 parts by mass or less, the coating film is resistant to contamination, the stability during preparation of the aqueous coating material, and the storage stability of the aqueous coating material without impairing the water resistance of the coating film. When the emulsion polymerization is carried out in the presence of a surfactant, the stability during polymerization is also improved.

  The polyoxyalkylene part of the anionic surfactant is used to increase the thickness of the outermost silica particle layer of the coating film, and to efficiently and effectively obtain a coating film having remarkable hydrophilicity and antistatic properties. Ethylene is preferable, and the number of repeating units is preferably 30 or less, and more preferably 20 or less.

  Examples of the aryl part of the anionic surfactant include phenyl, naphthyl, biphenyl, cumylphenyl, styrylphenyl, (mono-penta) benzylphenyl, (mono-penta) styrylphenyl, (mono-penta) styrylcyclohexylphenyl, ( Mono-penta) benzylbiphenyl, styrylcumylphenyl and the like.

  Examples of the sulfate salt of the anionic surfactant include sulfate ester sodium salt, sulfate ester potassium salt, sulfate ester calcium salt, sulfate ester ammonium salt and the like.

  Examples of nonionic surfactants include polyoxyalkylene alkyl ethers.

  In order to adjust the zeta potential absolute value of the aqueous coating material to 33 mV or more and 58 mV or less, the amount of the nonionic surfactant is preferably 0.1 to 0.9 parts by mass with respect to 100 parts by mass of the copolymer, 0.2-0.9 mass part is more preferable, and 0.4-0.9 mass part is further more preferable.

  The polyoxyalkylene part of the nonionic surfactant is used to increase the thickness of the outermost silica particle layer of the coating film, and to efficiently and effectively obtain a coating film having remarkable hydrophilicity and antistatic properties. Ethylene is preferred, and the repeating unit is preferably 10 or more, more preferably 20 or more. This effect becomes higher as the number of repeating units of polyoxyethylene is larger.

  Examples of the alkyl part of the nonionic surfactant include, for example, a linear or branched alkyl group having 4 to 18 carbon atoms, naphthyl, biphenyl, cumylphenyl, styrylphenyl, (mono-penta) benzylphenyl, (mono- Penta) styrylphenyl, (mono-penta) styrylcyclohexylphenyl, (mono-penta) benzylbiphenyl, styrylcumylphenyl and the like.

  In order to improve the stability at the time of preparation of the aqueous coating material, the storage stability of the aqueous coating material, and the polymerization stability when emulsion polymerization is performed in the presence of a surfactant, the above-mentioned anionic surfactants and nonionic surfactants are used. A known surfactant other than the activator may be used in combination.

(Other ingredients)
For water-based coating materials, pigments, antifoaming agents, pigment dispersants, leveling agents, anti-sagging agents, matting agents, UV absorbers, antioxidants, and heat resistance are improved in order to achieve high performance as coating materials. Various additives such as additives, slip agents, preservatives, plasticizers, film-forming aids; other emulsion resins, water-soluble resins, viscosity control agents, and curing agents such as melamines may be added.

Examples of the film-forming aid include those used in ordinary water-based paints, and examples thereof include the following.
C5-C10 linear, branched or cyclic aliphatic alcohols.
Alcohols containing aromatic groups.
Monoethers: (poly) ethylene glycol monoether or (poly) propylene glycol monoether represented by the following general formula (2).
^{_{HO- (CH 2 CHXO) n -R}} 3 ··· (2).
(Wherein R ³ represents a linear or branched alkyl group having 1 to 10 carbon atoms, X represents a hydrogen atom or a methyl group, and n represents an integer of 1 to 5)

Ether ester: (poly) ethylene glycol ether ester or (poly) propylene glycol ether ester represented by the following general formula (3).
_{^{R 4 COO- (CH 2 CHXO)}} n -R 5 ··· (3).
(In the formula, R ⁴ and R ⁵ represent a linear or branched alkyl group having 1 to 10 carbon atoms, X represents a hydrogen atom or a methyl group, and n represents an integer of 1 to 5. .)
Aromatic organic solvents: toluene, xylene, etc.
Other: 2,2,4-trimethyl-1,3-pentanediol mono- or diisobutyrate, 3-methoxybutanol, 3-methoxybutanol acetate, 3-methyl-3-methoxybutanol, 3-methyl-3-methoxy Butanol acetate etc.

<Preparation of aqueous coating material>
The aqueous coating material is prepared, for example, by mixing an aqueous dispersion of a copolymer, colloidal silica, a specific anionic surfactant, and a nonionic surfactant.
Specific anionic surfactants and nonionic surfactants may be added during the production process of the aqueous dispersion of the copolymer, and after the aqueous dispersion of the copolymer is produced, the aqueous coating material is prepared. You may add at the time.

(Aqueous dispersion of copolymer)
As an aqueous dispersion of a copolymer, an emulsion obtained by an emulsion polymerization method, a solution obtained by diluting the emulsion with water, a solution obtained by diluting a solution of a copolymer obtained by a solution polymerization method with water, Etc. Of these, emulsions obtained by emulsion polymerization or those diluted with water are preferred.

The absolute value of the zeta potential of the aqueous copolymer dispersion is from 36 mV to 57 mV. If the absolute value of the zeta potential of the aqueous dispersion of the copolymer is 36 mV or more, the storage stability of the aqueous dispersion of the copolymer is improved, and further, the storage stability is improved when the aqueous dispersion is prepared. . If the absolute value of the zeta potential of the aqueous dispersion of the copolymer is 57 mV or less, the aqueous dispersion of the copolymer can be obtained without impairing the storage stability when the aqueous dispersion of the copolymer or the aqueous coating material is prepared. The stain resistance of the coating film obtained from the aqueous coating material prepared using the liquid is improved.
The zeta potential of the aqueous copolymer dispersion is measured in the same manner as the zeta potential of the aqueous coating material.

The emulsion can be obtained by a known method such as a method of polymerizing a radical polymerizable monomer mixture with a radical polymerization initiator in the presence of a surfactant.
Examples of the surfactant include known anionic surfactants (including the specific anionic surfactant), cationic surfactants, nonionic surfactants, and polymer emulsifiers. Further, a so-called reactive emulsifier having a radical polymerizable unsaturated bond in the surfactant component may be used.

Examples of the radical polymerization initiator include the following compounds.
Persulfates: potassium persulfate, sodium persulfate, ammonium persulfate, etc.
Oil-soluble azo compounds: azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 2,2′-azobis (2,4-dimethylvaleronitrile), 2,2′-azobis (4-methoxy-2,4-dimethylvaleronitrile), 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile and the like.

Water-soluble azo compounds: 2,2′-azobis {2-methyl-N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide}, 2,2′-azobis {2-methyl- N- [2- (1-hydroxyethyl)] propionamide}, 2,2′-azobis {2-methyl-N- [2- (1-hydroxybutyl)] propionamide}, 2,2′-azobis [ 2- (5-Methyl-2-imidazolin-2-yl) propane] and its salts, 2,2′-azobis [2- (2-imidazolin-2-yl) propane] and its salts, 2,2′- Azobis [2- (3,4,5,6-tetrahydropyrimidin-2-yl) propane] and its salts, 2,2′-azobis {2- [1- (2-hydroxyethyl) -2-imidazoline-2 -Il] propane } And salts thereof, 2,2′-azobis (2-methylpropionamidine) and salts thereof, 2,2′-azobis (2-methylpropyneamidine) and salts thereof, 2,2′-azobis [N- ( 2-carboxyethyl) -2-methylpropionamidine] and salts thereof.
Organic peroxides: benzoyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, t-butyl peroxy-2-ethylhexanoate, t-butyl peroxyisobutyrate and the like.
These may be used individually by 1 type and may be used in combination of 2 or more type.

When acceleration of the polymerization rate or low temperature polymerization at 70 ° C. or lower is desired, it is advantageous to use a reducing agent such as sodium bisulfite, ferrous sulfate, ascorbate, Rongalite in combination with the radical polymerization catalyst. is there.
The amount of the radical polymerization initiator is usually 0.01 to 10 parts by mass with respect to 100 parts by mass of the total amount of the radical polymerizable monomers. 05-5 mass parts is preferable.

When adjusting the molecular weight of a copolymer, you may use a well-known chain transfer agent as a molecular weight modifier. Examples of the chain transfer agent include the following compounds.
Mercaptans: n-dodecyl mercaptan, t-dodecyl mercaptan, n-octyl mercaptan, n-tetradecyl mercaptan, n-hexyl mercaptan and the like.
Halogen compounds: carbon tetrachloride, ethylene bromide and the like.
Other: α-methylstyrene dimer and the like.
The amount of the chain transfer agent is usually 1 part by mass or less with respect to 100 parts by mass of the total amount of radical polymerizable monomers.

  The emulsion obtained by the emulsion polymerization method can be improved in stability by adding a basic compound to adjust its pH from neutral to weakly alkaline, that is, in the range of about pH 6.5 to 10.0. Examples of the basic compound include ammonia, triethylamine, propylamine, dibutylamine, amylamine, 1-aminooctane, 2-dimethylaminoethanol, ethylaminoethanol, 2-diethylaminoethanol, 1-amino-2-propanol, 2- Amino-1-propanol, 2-amino-2-methyl-1-propanol, 3-amino-1-propanol, 1-dimethylamino-2-propanol, 3-dimethylamino-1-propanol, 2-propylaminoethanol, Examples include ethoxypropylamine, aminobenzyl alcohol, morpholine, sodium hydroxide, potassium hydroxide and the like.

Examples of the particle structure of the copolymer in the emulsion include a single layer structure and a multilayer structure. The copolymer in the emulsion obtained by the multistage emulsion polymerization method has a multilayer structure, and the polymer forming the outermost layer has units derived from hydrolyzable silyl group-containing radical polymerizable monomers. It is preferable.
The unit derived from the hydrolyzable silyl group-containing radical polymerizable monomer is a component for improving the stain resistance, weather resistance and water resistance of the coating film. Reduce. Therefore, it is preferable to improve the stain resistance, weather resistance and water resistance of the coating film in a small amount, and a unit derived from a hydrolyzable silyl group-containing radical polymerizable monomer is introduced into the outermost layer of the multilayer structure particle. This purpose can be achieved. The radical polymerization initiator for copolymerizing the hydrolyzable silyl group-containing radical polymerizable monomer in the outermost layer is preferably a water-soluble azo compound from the viewpoint of stain resistance, weather resistance, and water resistance of the coating film. .

(Colloidal silica)
Colloidal silica is a colloidal liquid in which silica particles are dispersed in a dispersion medium. By using colloidal silica as the silica particles, the silica particles and the copolymer particles continue to maintain dispersion stability in the aqueous coating material, and the silica particles pass between the copolymer particles when forming a coating film. Thus, it is thought that the silica particle film is formed with a thickness so as to float on the surface of the coating film and cover the copolymer particles.

  A commercial item can be used as colloidal silica. The colloidal silica may be one using water as a dispersion medium, or one using an organic solvent as a dispersion medium.

Examples of the aqueous colloidal silica exhibiting acidity include the following commercially available products.
Product name: Snowtex OXS (SiO ₂ solid content 10% by mass), Snowtex OS (SiO ₂ solid content 20% by mass), Snowtex O (SiO ₂ solid content 20% by mass), manufactured by Nissan Chemical Industries, Ltd. Snowtex O-40 (SiO ₂ solid content 40% by mass), Snowtex OL (SiO ₂ solid content 20% by mass), Snowtex OUP (SiO ₂ solid content 15% by mass), and the like.
Asahi Denka Kogyo Co., Ltd., trade name: Adelite AT-20Q (SiO ₂ solid content 20% by mass), etc.
Product name: Cataloid SN (SiO ₂ solid content 20% by mass) manufactured by Catalyst Chemical Industry Co., Ltd.
Product name: Silica Dole-20A (SiO ₂ solid content 20% by mass), Silica Dole-20GA (SiO ₂ solid content 20% by mass), etc., manufactured by Nippon Chemical Industry Co., Ltd.

As aqueous colloidal silica which shows alkalinity, the following commercial item is mentioned, for example.
Product name: Snowtex XS (SiO ₂ solid content 20% by mass), Snowtex 20 (SiO ₂ solid content 20% by mass), Snowtex 30 (SiO ₂ solid content 30% by mass), manufactured by Nissan Chemical Industries, Ltd. Snowtex 40 (SiO ₂ solid content 40% by mass), Snowtex 50 (SiO ₂ solid content 50% by mass), Snowtex C (SiO ₂ solid content 20% by mass), Snowtex N (SiO ₂ solid content 20% by mass) ), Snowtex N-40 (SiO ₂ solid content 40 mass%), Snowtex NS (SiO ₂ solid content 20 mass%), Snowtex NXS (SiO ₂ solid content 10 mass%), Snowtex S (SiO ₂ solid content) 30% by mass), Snowtex CM (30% by mass of SiO ₂ solids), Snowtex UP (20% by mass of SiO ₂ solids), Snow -Tex 20L (SiO ₂ solid content 20% by mass), Snowtex XL (SiO ₂ solid content 40% by mass), and the like.
Asahi Denka Kogyo Co., Ltd., trade name: Adelite AT-20 (SiO ₂ solid content 20% by mass), Adelite AT-20N (SiO ₂ solid content 20% by mass), Adelite AT-20A (SiO ₂ solid content 20% by mass) %), Adelite AT-30, Adelite AT-40, Adelite AT-50, Adelite AT-30A, Adelite AT-300, Adelite AT-300S and the like.

Product name: Cataloid S-20L (SiO ₂ solid content 20% by mass), Cataloid S-20H (SiO ₂ solid content 20% by mass), Cataloid S-30L (SiO ₂ solid content 30% by mass) %), Cataloid S-30H (SiO ₂ solid content 30% by mass), Cataloid SI-30 (SiO ₂ solid content 30% by mass), Cataloid SI-40 (SiO ₂ solid content 40% by mass), Cataloid SI-50 ( SiO ₂ solid content 47% by mass), Cataloid SI-350 (SiO ₂ solid content 30% by mass), Cataloid SI-500 (SiO ₂ solid content 20% by mass), Cataloid SI-45P (SiO ₂ solid content 40% by mass) , Cataloid SI-80P (SiO ₂ solid content: 40 wt%), Cataloid SA (SiO ₂ solid content 30 wt%), Cataloid SC-30 (Si ₂ solid content: 30 wt%), and the like.
Product name: Silica Dole-20 (SiO ₂ solid content 20% by mass), Silica Dole-30 (SiO ₂ solid content 30% by mass), Silica Doll-40 (SiO ₂ solid content 40% by mass) %), Silica dol-30S (SiO ₂ solid content 30% by mass), silica dol-20AL (SiO ₂ solid content 20% by mass), silica dol-20A (SiO ₂ solid content 20% by mass), silica doll 20B (SiO 2 ₂ solid content 20% by mass), silica dol-20G (SiO ₂ solid content 20% by mass), silica dol-20GA (SiO ₂ solid content 20% by mass), ammonium silicate (SiO ₂ solid content 40% by mass), and the like.

Examples of the cationic colloidal silica include the following commercially available products.
Product name: Snowtex AK (SiO ₂ solid content 19% by mass) manufactured by Nissan Chemical Industries, Ltd.
Product name: Silica Doll-20P (SiO ₂ solid content 20% by mass), manufactured by Nippon Chemical Industry Co., Ltd.
These colloidal silica may be used individually by 1 type, and may be used in combination of 2 or more type.

<Painted object>
The coated article of the present invention is an article having a coating film obtained from the aqueous coating material of the present invention.
The coated product of the present invention is produced by applying the aqueous coating material of the present invention to a substrate or the like and drying to form a coating film on the substrate or the like.

  Examples of the base material include cement mortar, slate board, gypsum board, extruded board, foamable concrete, metal, glass, porcelain tile, asphalt, wood, waterproof rubber material, plastic, and calcium silicate base material. The aqueous coating material of the present invention can be positioned as a surface finishing material for these various substrates.

  Examples of the method of applying the aqueous coating material to the surface of various substrates include various coating methods such as spray coating, roller coating, bar coating, air knife coating, brush coating, and dipping.

  A coating film is obtained by drying the aqueous coating material applied on the surface of the base material at room temperature or by heating to 40 to 200 ° C. Also, after drying at a low temperature of about room temperature to about 50 ° C. to form a coating film, the coating film is heated to a temperature higher than the glass transition temperature of the copolymer to strengthen the binding between the copolymer particles. A coating film with higher weather resistance can also be obtained.

  Examples of the coated object of the present invention include building materials, building exteriors, building interiors, window frames, window glass, structural members, plate materials, vehicle exteriors, exteriors of machinery and articles, dustproof covers, reflectors for road signs, and line of sight Guide signs, road markings, various display devices, advertising towers, sound insulation walls for roads, sound insulation walls for railways, road decorative panels, light source covers for traffic lights, outdoor display boards, bridges, guardrails, tunnel interiors, lighting devices in tunnels, glass, Solar battery cover, solar water heater heat collection cover, plastic house, vehicle lighting cover, road mirror, vehicle mirror, motorcycle weighing cover and weighing panel, glass lens, plastic lens, helmet shield, goggles, house, Window glass for automobiles and railway vehicles, vehicle windshields, showcases, heat insulation showcases, membrane structural materials, heat exchange fins, glass surfaces at various locations, Lined, tire wheel, roofing material, roofing roof, antenna, transmission line, housing equipment, toilet bowl, bathtub, wash basin, lighting fixture, lighting cover, kitchenware, tableware, tableware container, dishwasher, dish dryer, sink , Cooking range, kitchen hood, ventilation fan, aquarium material for viewing, surface material in contact with circulating water in facilities using circulating water, anti-thrombogenic material, anti-protein adhesion material, anti-lipid adhesion material, contact lens, urination Catheters, transcutaneous devices, artificial organs, blood bags, blood collection bags, lung drainage, ship bottoms, tent canvas, slides, functional fibers, TVs, displays such as TVs, PCs, films to be affixed to these items, etc. Can be mentioned.

  The aqueous coating material of the present invention described above contains a copolymer, silica particles, a specific anionic surfactant, and a nonionic surfactant, and the amount of silica particles is The coating film has excellent contamination resistance, transparency, weather resistance, and frost damage resistance because the absolute value of zeta potential of the aqueous coating material is 58 mV or less with respect to 100 parts by mass of the coalescence. Can be formed. Moreover, in the aqueous coating material of this invention, since the zeta potential absolute value of the aqueous coating material is 33 mV or more, it is excellent in storage stability.

  Since the coated article of the present invention described above has a coating film obtained from the aqueous coating material of the present invention, the coating film is excellent in stain resistance, transparency, weather resistance, and frost damage resistance. That is, by using the water-based coating material of the present invention, a silica particle layer having a certain thickness and spreading on the surface of the coating film is formed on the outermost layer of the coating film, thereby imparting remarkable hydrophilicity to the coating film. The self-cleaning effect of rainwater will be demonstrated. Furthermore, since the silica particles come into contact with each other on the surface of the coating film, the coating film surface has conductivity, and adhesion of dirt due to static electricity is suppressed. As a result, the coating film of the present invention exhibits excellent stain resistance. The coated product of the present invention is only a coating film obtained from the aqueous coating material of the present invention, and exhibits sufficient stain resistance. Therefore, it is not always necessary to have a multi-layer structure consisting of a conventional overcoating, intermediate coating, and undercoating. Also good.

EXAMPLES Hereinafter, although an Example demonstrates this invention in detail, this invention is not limited at all by this Example.
The evaluation of the coating film was performed according to the following method.

(Monomer unit content)
The content of monomer units in the copolymer is determined by pyrolysis gas chromatograph (gas chromatograph: manufactured by Agilent Technologies, thermal decomposition apparatus: manufactured by Nihon Analytical Industries, Ltd.), Fourier transform infrared spectrophotometer (Nikolay Japan ( Etc.).

(Zeta potential)
Using DT-1200 (manufactured by Dispersion Technology), the zeta potential of the aqueous coating material and the zeta potential of the aqueous dispersion of the copolymer were measured to obtain absolute values.

(Production of test plates for evaluation of water contact angle, carbon contamination resistance, storage stability and weather resistance)
An aqueous coating material was applied to a zinc phosphate-treated steel plate (bonderite # 100-treated steel plate, plate thickness 0.8 mm, length 150 mm × width 70 mm) with a bar coater # 60 in an atmosphere of 40 ° C., at 130 ° C. Dry for 5 minutes. Then, what was dried at room temperature for 1 day was used as a test plate for evaluation of water contact angle, carbon contamination resistance, storage stability and weather resistance.

(Preparation of anti-static evaluation test plate)
An aqueous coating composition was applied to a polyethylene terephthalate film with a bar coater # 60 in an atmosphere of 40 ° C. and dried at 130 ° C. for 5 minutes. Then, what was dried at room temperature for 1 day was used as an antistatic evaluation test plate.

(Preparation of test plates for transparency evaluation)
An aqueous coating material was applied to a glass plate with a 4 MIL applicator in an atmosphere of 40 ° C., and dried at 130 ° C. for 5 minutes to obtain a test plate for evaluation.

(Preparation of test panels for evaluation of outdoor exposure contamination resistance)
Dianal LX-2011 (trade name, manufactured by Mitsubishi Rayon Co., Ltd.) was used as an intermediate coating on a zinc phosphate-treated steel plate (bonderite # 100-treated steel plate, plate thickness 0.8 mm, length 300 mm × width 100 mm). White enamel paint (PWC (pigment content ratio) = 40% by mass) was spray-coated at room temperature so that the dry film thickness was 50 μm, and dried at 130 ° C. for 5 minutes. Next, an aqueous coating material was spray-coated at room temperature so that the dry film thickness was 30 μm, dried at 130 ° C. for 5 minutes, and then dried at room temperature for 1 day. It was.

(Preparation of test plates for evaluation of frost resistance)
White enamel paint (PWC = 40% by mass) using a dial LX-1010 (trade name, manufactured by Mitsubishi Rayon Co., Ltd.) as a sealer on a gypsum slag perlite plate (thickness 12 mm) with a coating amount of 90- Spray coating was performed at room temperature so as to be 100 g / m ² (wet mass), followed by drying at 130 ° C. for 5 minutes. Subsequently, a white enamel paint (PWC = 40 mass%) using Dianal LX-2011 (trade name, manufactured by Mitsubishi Rayon Co., Ltd.) as an intermediate coating is applied in an amount of 90 to 100 g / m ² (wet mass). It was spray coated at room temperature so that Next, the aqueous coating material was spray-coated at room temperature so that the coating amount was 50 to 60 g / m ² (wet mass), dried at 130 ° C. for 5 minutes, and then dried at room temperature for 1 day. A test plate for evaluation of frost resistance.

(Water contact angle)
Using a CA-X150 type FACE contact angle meter (manufactured by Kyowa Interface Science Co., Ltd.), 0.4 μL (three scales on the screen) of water droplets was dropped on the coating film of the evaluation test plate, and 30 seconds later. The water contact angle was measured.

(Antistatic)
The test plate for evaluation was attached to STATIC HONES TMETER S-5109 (manufactured by Sicid Electrostatic Co., Ltd.), half-life measurement shown in JIS L 1094 was performed, and the following criteria were used. At this time, after applying plus 10 kV for 30 seconds, the application was stopped, and measurement was performed for 180 seconds from the start of application while rotating the turntable.
“◎”: less than 30 seconds.
“◯”: 30 seconds or more and less than 90 seconds.
“Δ”: 90 seconds or more and less than 180 seconds.
“×”: 180 seconds or more.

(Carbon decontamination)
Immediately after spraying water on the coating film of the test plate for evaluation with a spray, a carbon solution containing 10% by mass of carbon MA100 (manufactured by Mitsubishi Chemical Corporation) in petroleum benzine was dropped using a dropper, and after 5 seconds. Rinse with tap water. About the part which dipped the carbon solution, the adhesion degree to the coating film of carbon was observed visually, and the following reference | standard determined.
“◎”: No adhesion.
“◯”: Slightly adhered partially.
“△”: Thinly adhered to the entire surface.
"X": It adheres to the whole surface deeply.

(Storage stability)
An aqueous coating material sealed in a mayonnaise bottle was immersed in warm water at 50 ° C. for 15 days, and then returned to room temperature, to prepare a test plate for evaluation. The water contact angle of the coating film of the test plate for evaluation was measured and judged according to the following criteria.
“◎”: The increase in measured value is less than 10 ° compared to the water contact angle of the coating film before the storage stability test.
“◯”: Compared with the water contact angle of the coating film before the storage stability test, the increase in the measured value is 10 ° or more and less than 15 °.
“Δ”: The increase in the measured value is 15 ° or more and less than 30 ° compared to the water contact angle of the coating film before the storage stability test.
“X”: The measured value increased by 30 ° or more compared to the water contact angle of the coating film before the storage stability test.

(transparency)
The transparency of the coating film of the evaluation test plate was visually observed and judged according to the following criteria.
“O”: Transparent.
“△”: Translucent.
“×”: cloudiness.

(Outdoor exposure contamination resistance)
Fold the test plate for evaluation at a third of the length from the top so that the inner angle is 135 degrees, and let the test plate face the south side in the Mitsubishi Rayon Co., Ltd. Toyohashi Office (Ushikawa-dori, Toyohashi City) Installed so that the surface with the larger area (vertical surface) is vertical and the surface with the smaller area (upper surface) on top, and after exposure for 6 months from May to October 2006, paint on the upper surface The difference ΔL in whiteness before and after exposure of the film was measured with a color difference meter, and the presence or absence of rain streak on the vertical surface was visually evaluated. Judgment criteria are shown below.
(Difference in whiteness before and after exposure on the upper surface ΔL)
“◎”: less than 2.5.
“◯”: 2.5 or more and less than 5.0.
“Δ”: 5.0 or more and less than 7.5.
"X": 7.5 or more.
(Presence or absence of rain stripes on the vertical surface)
“◎”: No rain stripe contamination.
“O”: Slightly contaminated rain stripes.
“×”: Rain line contamination is clearly observed.

(Weatherability)
A test plate having a size of 70 mm × 50 mm is cut from the test plate for evaluation, and the test plate is put into a die plastic metal weather KU-R4-W type (manufactured by Daipura Wintes Co., Ltd.). Test cycle: irradiation 4 hours (Spray 5 seconds / 15 minutes) / condensation 4 hours, UV intensity: 85 mW / cm ² , black panel temperature: 63 ° C. during irradiation / 30 ° C. during condensation, humidity: 50% RH during irradiation / 96% RH during condensation The weather resistance test was conducted. Using the 60 ° gloss retention of the coating after 600 hours as an indicator of weather resistance, the following criteria were used.
“◎”: 80% or more.
“◯”: 70% or more and less than 80%.
“Δ”: 60% or more and less than 70%.
"X": Less than 60%.

(Frost damage resistance)
Measurement was performed by the ASTM-C666A method (200 cycles), and the determination was made according to the following criteria.
“◎”: No crack or gloss change.
“◯”: No crack, but slightly glossy.
“△”: Minor cracks occurred.
“×”: Remarkable cracking occurred.

[Production Example 1]
Preparation of aqueous dispersion of polyorganosiloxane:
95 parts by mass of cyclic dimethylsiloxane oligomer 3 to 7-mer mixture, 5 parts by mass of γ-methacryloyloxypropyltrimethoxysilane, 250 parts by mass of deionized water, 0.4 part by mass of sodium dodecylbenzenesulfonate and 0 part of dodecylbenzenesulfonic acid A composition consisting of 4 parts by mass was premixed with a homomixer and forcibly emulsified with a pressure homogenizer at a pressure of 200 kg / cm ² to obtain a raw material pre-emulsion.

  Next, 55 parts by mass of water and 5 parts by mass of dodecylbenzenesulfonic acid were charged into a flask equipped with a stirrer, a reflux condenser, a temperature controller and a dropping pump, and the internal temperature of the flask was maintained at 85 ° C. with stirring. The raw material pre-emulsion was added dropwise over 4 hours. After completion of the dropwise addition, the polymerization was further allowed to proceed for 1 hour, cooled, and dodecylbenzenesulfonic acid and an equimolar amount of ammonia were added to prepare a polyorganosiloxane aqueous dispersion (SiEm). The solid content was 22.7% by mass.

[Example 1]
In a flask equipped with a stirrer, reflux condenser, temperature controller, and dropping pump, 80 parts by mass of deionized water, New Coal 707SF (trade name, manufactured by Nippon Emulsifier Co., Ltd., anionic surfactant, polyoxyalkylene alkylaryl) Sulfuric ester of ether (Chemical Examination Law Official Journal publication name: polyoxyalkylene (C = 2 to 3) alkyl (C = 1,8,9) (mono-penta) styryl-phenyl ether sulfate) 2.5 Radicals that are constituent components of the copolymer, shown in parts by mass (solid content: 0.75 parts by mass), 4 parts by mass of SiEm (solid content: 0.9 parts by mass), and “first stage (inner layer)” in Table 1 A mixture of polymerizable monomers was charged. After raising the internal temperature of the flask to 50 ° C., an initiator aqueous solution of 0.15 part by weight of ammonium persulfate / 1 part by weight of deionized water was added, and 0.05 part by weight of sodium bisulfite / 1 part by weight of deionized water. Part of the reducing agent aqueous solution was added. After confirming the peak top temperature due to polymerization exotherm, the internal temperature of the flask was maintained at 65 ° C., and 1 hour after the addition of the reducing agent aqueous solution, Emulgen 1150S-70 (trade name, manufactured by Kao Corporation, nonionic surfactant) ) 0.5 parts by mass (solid content 0.3 parts by mass) /0.5 parts by mass of deionized water was added.

  0.5 hours after addition of the surfactant aqueous solution, a mixture of radical polymerizable monomers shown in “Second stage (outer layer)” of Table 1, 22 parts by mass of deionized water, 10 parts by mass of New Coal 707SF, And AMP-90 (trade name, manufactured by Dow Chemical Japan Co., Ltd., basic compound) 0.115 parts pre-emulsified and dispersed, and VA-061 (trade name, Wako Pure Chemical Industries, Ltd.) (Manufactured, radical polymerization initiator) 0.1 parts by mass / methanol 2 parts by mass / deionized water 3 parts by mass of an initiator solution was dropped in two series over 1.5 hours. During the dropping, the internal temperature of the flask was maintained at 65 ° C., and after the dropping was completed, the temperature was maintained at 65 ° C. for 1 hour. After adding 0.98 parts by mass of AMP-90, the mixture was further maintained at 65 ° C. for 0.5 hour. Then, it cooled to room temperature and obtained the aqueous dispersion liquid of the copolymer. The content of the unit derived from the hydrolyzable silyl group-containing radical polymerizable monomer was 2.05 parts by mass with respect to 100 parts by mass of the copolymer (solid content). The zeta potential of the aqueous copolymer dispersion was measured. The results are shown in Table 1.

To the aqueous dispersion of the copolymer, 25 parts by mass (5 parts by mass of solid content) of Snowtex N (trade name, manufactured by Nissan Chemical Industries, Ltd., colloidal silica, average particle diameter of silica particles of 15 nm) is added. Then, 5 parts by mass of butyl cellosolve was added as a film forming aid to obtain an aqueous coating material. The amount of silica particles (solid content) was 5 parts by mass with respect to 100 parts by mass of the copolymer (solid content).
The zeta potential of the obtained aqueous coating material was measured. The results are shown in Table 1.
In addition, a coating film is formed using an aqueous coating material, and water contact angle, antistatic property, carbon contamination resistance, storage stability, transparency, outdoor exposure contamination resistance, weather resistance, and frost damage resistance are evaluated. It was. The results are shown in Table 3.

[Example 2]
An aqueous copolymer dispersion was obtained in the same manner as in Example 1 except that the amount of the nonionic surfactant was changed to the amount shown in Table 1. The content of the unit derived from the hydrolyzable silyl group-containing radical polymerizable monomer was 2.05 parts by mass with respect to 100 parts by mass of the copolymer (solid content). The zeta potential of the aqueous copolymer dispersion was measured. The results are shown in Table 1.

An aqueous coating material was obtained in the same manner as in Example 1. The amount of silica particles (solid content) was 5 parts by mass with respect to 100 parts by mass of the copolymer (solid content).
The zeta potential of the obtained aqueous coating material was measured. The results are shown in Table 1.
In addition, a coating film is formed using an aqueous coating material, and water contact angle, antistatic property, carbon contamination resistance, storage stability, transparency, outdoor exposure contamination resistance, weather resistance, and frost damage resistance are evaluated. It was. The results are shown in Table 3.

Example 3
An aqueous copolymer dispersion was obtained in the same manner as in Example 1 except that the amount of the nonionic surfactant was changed to the amount shown in Table 1. The content of the unit derived from the hydrolyzable silyl group-containing radical polymerizable monomer was 2.05 parts by mass with respect to 100 parts by mass of the copolymer (solid content). The zeta potential of the aqueous copolymer dispersion was measured. The results are shown in Table 1.

An aqueous coating material was obtained in the same manner as in Example 1. The amount of silica particles (solid content) was 5 parts by mass with respect to 100 parts by mass of the copolymer (solid content).
The zeta potential of the obtained aqueous coating material was measured. The results are shown in Table 1.
In addition, a coating film is formed using an aqueous coating material, and water contact angle, antistatic property, carbon contamination resistance, storage stability, transparency, outdoor exposure contamination resistance, weather resistance, and frost damage resistance are evaluated. It was. The results are shown in Table 3.

Example 4
An aqueous copolymer dispersion was obtained in the same manner as in Example 1 except that the amount of the nonionic surfactant was changed to the amount shown in Table 1. The content of the unit derived from the hydrolyzable silyl group-containing radical polymerizable monomer was 2.05 parts by mass with respect to 100 parts by mass of the copolymer (solid content). The zeta potential of the aqueous copolymer dispersion was measured. The results are shown in Table 1.

An aqueous coating material was obtained in the same manner as in Example 1 except that the amount of colloidal silica was changed as shown in Table 1. The amount of silica particles (solid content) was 10 parts by mass with respect to 100 parts by mass of the copolymer (solid content).
The zeta potential of the obtained aqueous coating material was measured. The results are shown in Table 1.
In addition, a coating film is formed using an aqueous coating material, and water contact angle, antistatic property, carbon contamination resistance, storage stability, transparency, outdoor exposure contamination resistance, weather resistance, and frost damage resistance are evaluated. It was. The results are shown in Table 3.

Example 5
An aqueous copolymer dispersion was obtained in the same manner as in Example 1 except that the amount of the nonionic surfactant was changed to the amount shown in Table 1. The content of the unit derived from the hydrolyzable silyl group-containing radical polymerizable monomer was 2.05 parts by mass with respect to 100 parts by mass of the copolymer (solid content). The zeta potential of the aqueous copolymer dispersion was measured. The results are shown in Table 1.

As shown in Table 1, the aqueous colloidal silica was replaced with Snowtex NS (trade name, manufactured by Nissan Chemical Industries, Ltd., colloidal silica, silica particles having an average particle diameter of 10 nm) in the same manner as in Example 1 to obtain an aqueous solution. A coating was obtained. The amount of silica particles (solid content) was 5 parts by mass with respect to 100 parts by mass of the copolymer (solid content).
The zeta potential of the obtained aqueous coating material was measured. The results are shown in Table 1.
In addition, a coating film is formed using an aqueous coating material, and water contact angle, antistatic property, carbon contamination resistance, storage stability, transparency, outdoor exposure contamination resistance, weather resistance, and frost damage resistance are evaluated. It was. The results are shown in Table 3.

[Comparative Example 1]
An aqueous copolymer dispersion was obtained in the same manner as in Example 1 except that the amount of the nonionic surfactant was changed to the amount shown in Table 2. The content of the unit derived from the hydrolyzable silyl group-containing radical polymerizable monomer was 2.05 parts by mass with respect to 100 parts by mass of the copolymer (solid content). The zeta potential of the aqueous copolymer dispersion was measured. The results are shown in Table 2.

An aqueous coating material was obtained in the same manner as in Example 1. The amount of silica particles (solid content) was 5 parts by mass with respect to 100 parts by mass of the copolymer (solid content).
The zeta potential of the obtained aqueous coating material was measured. The results are shown in Table 2.
In addition, a coating film is formed using an aqueous coating material, and water contact angle, antistatic property, carbon contamination resistance, storage stability, transparency, outdoor exposure contamination resistance, weather resistance, and frost damage resistance are evaluated. It was. The results are shown in Table 3.

[Comparative Example 2]
An aqueous copolymer dispersion was obtained in the same manner as in Example 1 except that the amount of the nonionic surfactant was changed to the amount shown in Table 2. The content of the unit derived from the hydrolyzable silyl group-containing radical polymerizable monomer was 2.05 parts by mass with respect to 100 parts by mass of the copolymer (solid content). The zeta potential of the aqueous copolymer dispersion was measured. The results are shown in Table 2.

An aqueous coating material was obtained in the same manner as in Example 1. The amount of silica particles (solid content) was 5 parts by mass with respect to 100 parts by mass of the copolymer (solid content).
The zeta potential of the obtained aqueous coating material was measured. The results are shown in Table 2.
In addition, a coating film is formed using an aqueous coating material, and water contact angle, antistatic property, carbon contamination resistance, storage stability, transparency, outdoor exposure contamination resistance, weather resistance, and frost damage resistance are evaluated. It was. The results are shown in Table 3.

[Comparative Example 3]
An aqueous copolymer dispersion was obtained in the same manner as in Example 1 except that the amount of the nonionic surfactant was changed to the amount shown in Table 2. The content of the unit derived from the hydrolyzable silyl group-containing radical polymerizable monomer was 2.05 parts by mass with respect to 100 parts by mass of the copolymer (solid content). The zeta potential of the aqueous copolymer dispersion was measured. The results are shown in Table 2.

An aqueous coating material was obtained in the same manner as in Example 1. The amount of silica particles (solid content) was 5 parts by mass with respect to 100 parts by mass of the copolymer (solid content).
The zeta potential of the obtained aqueous coating material was measured. The results are shown in Table 2.
In addition, a coating film is formed using an aqueous coating material, and water contact angle, antistatic property, carbon contamination resistance, storage stability, transparency, outdoor exposure contamination resistance, weather resistance, and frost damage resistance are evaluated. It was. The results are shown in Table 3.

The abbreviations in Tables 1 and 2 indicate the following compounds.
“MMA”: methyl methacrylate,
“2-HEMA”: 2-hydroxyethyl methacrylate,
“EDMA”: ethylene dimethacrylate,
“N-BA”: n-butyl acrylate,
“SZ-6030”: γ-methacryloyloxypropyltrimethoxysilane (manufactured by Dow Corning Toray Silicone Co., Ltd.),
“MAA”: methacrylic acid,
“N-BMA”: n-butyl methacrylate,
“ZM-84”: unsaturated fatty acid hydroxyalkyl ester modified ε-caprolactone (ε-caprolactone modified 2-hydroxyethyl methacrylate),

  As is apparent from Table 3, the water-based coating materials of the examples are excellent in storage stability, and the coating film has good water contact angle and antistatic properties, so that it is resistant to contamination (carbon decontamination and anti-resistance). It was excellent in outdoor exposure pollution) and had transparency, weather resistance, and frost resistance. On the other hand, it was difficult for the aqueous coating material of the comparative example and its coating film to exhibit storage stability, stain resistance, transparency, weather resistance, and frost damage resistance in a well-balanced manner.

  The aqueous coating material of the present invention has excellent storage stability by increasing the repulsive force between particles, and the coating film has excellent stain resistance, transparency, weather resistance, water resistance, and frost damage resistance. Become. Such a water-based coating material and the coating film thereof can be used for various coating applications for the purpose of protecting the housing of buildings, civil engineering structures, and the like, and are extremely useful industrially.

Claims (2)

A copolymer;
Silica particles;
Polyoxyalkylene aryl ether sulfate ester salt, polyoxyalkylene alkyl aryl ether sulfate ester salt, polyoxyalkylene aryl ether sulfate ester formalin condensate, and polyoxyalkylene alkyl aryl ether sulfate ester formalin condensate At least one anionic surfactant selected from the group consisting of:
It is an aqueous coating material containing a nonionic surfactant,
The amount of the silica particles is 0.5 to 20 parts by mass with respect to 100 parts by mass of the copolymer,
An aqueous coating material, wherein the absolute value of the zeta potential of the aqueous coating material is 33 mV or more and 58 mV or less.   A coated article having a coating film obtained from the aqueous coating material according to claim 1.