JP2015113402A - Water-based coating material and coated article - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a water-based coating material capable of obtaining a coating film excellent in hydrophilicity, durability, optical properties and also transparency, and a coated article having a coating film obtained by applying the water-based coating material.SOLUTION: The water-based coating material includes a polymer (I) and particles (II) in which metal particles are coated with a silica layer. The particles (II) of 0.1-13 pts.mass are included to the polymer (I) of 100 pts.mass, and an average film thickness of the silica layers of the particles (II) is 1.0 nm or more.

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 has been attempted from the viewpoints of environmental protection and safety and health. However, the water-based paint has a problem that the obtained coating film has low stain resistance and durability compared to the organic solvent-based paint. Therefore, by combining an inorganic material excellent in hydrophilicity, optical characteristics, and durability with water-based paint, the surface of the coating film is given self-cleaning ability by water such as rain, thereby improving stain resistance. In some cases, the coating film is imparted with optical properties such as ultraviolet absorption ability to improve durability.
For example, Patent Document 1 discloses an aqueous coating material containing silica-coated zinc oxide particles and an aqueous dispersion polymer. Patent Document 2 discloses an aqueous coating material containing colloidal silica and silica-coated titanium oxide particles and an aqueous dispersion polymer. Furthermore, Patent Document 3 discloses an aqueous coating material containing colloidal silica and an aqueous dispersion polymer.

JP 2003-292818 A JP 2008-031297 A International Publication No. 2010/143413

W. Stober, A.M. Fink and E.M. Bohn, J .; Colloid Interface Sci. , 26, 1, 62-69, 1968.

However, although the water-based coating material described in Patent Document 1 has excellent ultraviolet absorptivity, since the content of inorganic particles in the water-based coating material is high, the excellent flexibility and the like of the polymer are impaired. In some cases, the durability of the obtained coating film was low. Moreover, although the aqueous coating material described in Patent Document 2 has excellent hydrophilicity, the obtained coating film does not have optical properties such as ultraviolet absorption. Moreover, in order to obtain a coating film excellent in hydrophilicity, it is necessary to increase the content of inorganic particles contained in the aqueous coating material.
Patent Document 3 discloses that the coating film obtained with at least the content of inorganic particles exhibits high hydrophilicity, but has a problem of poor optical properties such as ultraviolet absorption.
In addition, if the average particle size is relatively large, such inorganic particles not only absorb and scatter ultraviolet rays, but also scatter visible light, and a coating obtained from an aqueous coating material containing these inorganic particles. There is also a problem that the film becomes cloudy or has a high haze value, resulting in a decrease in transparency.

  The present invention has been made in view of the above-described problems, and has an aqueous coating material that has excellent hydrophilicity and optical characteristics, and further has excellent transparency, and the aqueous coating material is applied. An object of the present invention is to provide a coated article having a coating film obtained in this way.

The present invention has the following aspects.
[1] An aqueous coating material containing a polymer (I) and particles (II) in which metal particles are coated with a silica layer, and the particles (II) with respect to 100 parts by mass of the polymer (I) ) In an amount of 0.1 to 13 parts by mass, and the average thickness of the silica layer of the particles (II) is 1.0 nm or more;
[2] The aqueous coating material according to [1], wherein the particles (II) have an average particle size of 2 to 600 nm;
[3] The aqueous coating material according to [1] or [2], wherein the metal particles are metal oxides;
[4] The aqueous coating material according to [3], wherein the metal oxide is at least one selected from the group consisting of cerium oxide, zinc oxide, and titanium oxide;
[5] The aqueous coating material according to any one of [1] to [4], further including a nonionic surfactant, and the nonionic system with respect to 100 parts by mass of the polymer (I). An aqueous coating material containing 0.01 to 3 parts by mass of a surfactant;
[6] The aqueous coating material according to [5], wherein the nonionic surfactant has an HLB of 16 or more;
[7] The aqueous coating material according to any one of [1] to [6], further comprising an anionic surfactant, wherein the anionic surfactant is a sulfate of polyoxyalkylene aryl ether At least one selected from the group consisting of a salt, a formalin condensate of a polyoxyalkylene alkylaryl ether sulfate, a polyoxyalkylene aryl ether sulfate, and a formalin condensate of a polyoxyalkylene alkylaryl ether sulfate. Water-based coatings that are two anionic surfactants;
[8] The polymer (I) according to any one of [1] to [7], wherein the polymer (I) is a copolymer obtained by polymerizing at least two types of radical polymerizable monomers (A). Water-based coating material;
[9] The radical polymerizable monomer (A) includes a monomer (a1) having two or more radical polymerizable groups in the molecule and a radical polymerizable monomer containing a hydrolyzable silyl group in the molecule. The aqueous coating material according to [8], comprising at least one monomer selected from the group consisting of a monomer (a2);
[10] A coated article having a coating film obtained from the aqueous coating material according to any one of [1] to [9];
[11] The painted product according to [10], wherein a water contact angle on the surface of the painted product is 60 degrees or less.

  The coating film obtained from the aqueous coating material of the present invention is excellent in hydrophilicity and optical properties, and can also achieve both transparency.

<Water-based coating material>
The aqueous coating material of the present invention includes a polymer (I) and particles (II) in which metal particles are coated with a silica layer, and the particles (II) with respect to 100 parts by mass of the polymer (I). 0.1 to 13 parts by mass, and the average film thickness of the silica layer of the particles (II) is 1.0 nm or more.
Hereinafter, the present invention will be described in detail.

[Polymer (I)]
In one embodiment of the present invention, the polymer (I) is obtained by polymerizing various radically polymerizable monomers (A).

(Radical polymerizable monomer (A))
Examples of the radical polymerizable monomer (A) constituting the polymer (I) include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, The carbon number of 1-18, such as sec-butyl (meth) acrylate, t-butyl (meth) acrylate, glycidyl (meth) acrylate, cyclohexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, etc. Alkyl (meth) acrylates having an alkyl group; hydroxyl group-containing radical polymerizable monomers such as 2-hydroxyethyl (meth) acrylate; hydroxypolyethylene oxide mono (meth) acrylate, hydroxypolypropylene oxide mono (meth) acrylate, etc. End Hydroxy type polyalkylene oxide group-containing radical polymerizable monomer; alkyl group-terminated polyalkylene oxide group-containing radical polymerizable monomer such as methoxypolyethylene oxide mono (meth) acrylate; oxirane group containing glycidyl (meth) acrylate and the like Photo-stabilizing action of radically polymerizable monomer; 1,2,2,6,6-pentamethyl-4-piperidyl (meth) acrylate, 2,2,6,6-pentamethyl-4-piperidyl (meth) acrylate (Meth) acrylate having a UV-absorbing component such as 2- [2′-hydroxy-5 ′-(meth) acryloyloxyethylphenyl] -2H-benzotriazole; 2-aminoethyl (meta) ) Aminoalkyl (meth) acrylates such as acrylate; ) Amide group-containing radical polymerizable monomers such as acrylamide; (Meth) acrylonitrile, benzyl (meth) acrylate, isobornyl (meth) acrylate, (meth) acrylic monomers such as methoxyethyl (meth) acrylate; styrene, Aromatic vinyl monomers such as methylstyrene; Carbonyl group and / or aldehyde group-containing ethylenically unsaturated monomers such as acrolein, diacetone acrylamide, formyl styrene, vinyl alkyl ketone, etc .: 1,3-butadiene, isoprene, etc. Conjugated diene monomers such as: radically polymerizable monomers such as vinyl acetate, vinyl chloride, and ethylene.
These radical polymer monomers (A) are preferably used in combination of two or more.
In the present specification, “(meth) acrylate” means “acrylate” and / or “methacrylate”.
Moreover, in one aspect of the present invention, the mass average molecular weight of the polymer (I) is preferably 50,000 to 5,000,000, and more preferably 100,000 to 4,000,000. The mass average molecular weight is a value measured by gel permeation chromatography.

(Monomer (A1) having radically polymerizable carboxylic acid in the molecule)
Furthermore, from the viewpoint of the stability of the resulting aqueous coating material, a monomer (A1) having a radically polymerizable carboxylic acid in the molecule is used as the radically polymerizable monomer (A) constituting the polymer (I). It is preferable to include. Examples of the monomer (A1) having a radical polymerizable carboxylic acid in the molecule include (meth) acrylic acid, itaconic acid, citraconic acid, maleic acid, monomethyl maleate, monobutyl maleate, monomethyl itaconic acid, and itaconic acid. Monobutyl, vinyl benzoic acid, monohydroxyethyl (meth) acrylate oxalate, monohydroxyethyl (meth) acrylate tetrahydrophthalate, monohydroxypropyl tetrahydrophthalate (meth) having both carboxylic acid group and hydroxyl group Acrylate, 5-hydroxy-1,2-cyclohexanedicarboxylic acid monohydroxyethyl (meth) acrylate, phthalate monohydroxyethyl (meth) acrylate, phthalate monohydroxypropyl (meth) acrylate, maleate Hydroxyethyl (meth) acrylate, maleic acid hydroxypropyl (meth) acrylate, tetrahydrophthalic acid mono-hydroxybutyl (meth) acrylate. Of these, acrylic acid and methacrylic acid are preferred. As the radical polymerizable carboxylic acid (A1) in these molecules, one kind may be used alone, or two or more kinds may be used in combination.

  Furthermore, from the viewpoint of the hydrophilicity of the resulting coating film, the monomer (a1) having two or more radically polymerizable groups in the molecule as the radically polymerizable monomer (A) constituting the polymer (I) And at least one monomer selected from the group consisting of radically polymerizable monomers (a2) containing hydrolyzable silyl groups in the molecule.

(Monomer (a1) having two or more radically polymerizable groups in the molecule)
Examples of the monomer (a1) having two or more radically polymerizable groups in the molecule include ethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, and propylene glycol. Di (meth) acrylate, polypropylene glycol di (meth) acrylate, 1,3-butylene glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, 2-hydroxy -1,3-di (meth) acryloxypropane, 2,2-bis [4- (acryloxyethoxy) phenyl] propane, 2,2-bis [4- (methacryloxyethoxy) phenyl] propane, 2,2 -Bis [4- (acryloxy polyester Xyl) phenyl] propane, 2,2-bis [4- (methacryloxy polyethoxy) phenyl] propane, 2-hydroxy-1-acryloxy-3-methacryloxypropane, ethylene oxide modified bisphenol A di (meth) acrylate, propylene oxide Modified bisphenol A di (meth) acrylate, ethylene oxide-modified hydrogenated bisphenol A di (meth) acrylate, propylene oxide-modified hydrogenated bisphenol A di (meth) acrylate, diglycidyl ether of bisphenol A and hydroxy (meth) acrylate Diols such as epoxy (meth) acrylates to which alkyl (meth) acrylate is added, polyoxyalkylenated bisphenol A di (meth) acrylate, and (meth) acrylic acid Diester compounds; metal-containing radical polymerizable monomers such as zinc di (meth) acrylate; trimethylolpropane tri (meth) acrylate, tetramethylolmethanetri (meth) acrylate, tetramethylolmethanetetra (meth) acrylate, pentaerythritol Compounds having 3 or more hydroxyl groups per molecule such as tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and (meth) acrylic acid Polyester compounds of allyl (meth) acrylate, divinylbenzene, triallyl (iso) cyanurate, diallyl iso (tere) phthalate, diallyl isocyanurate, diallyl tris maleate (2-a (Acryloyloxyethylene) isocyanurate, ε-caprolactone-modified tris (acryloxyethyl) isocyanurate. Among these, ethylene glycol di (meth) acrylate, allyl (meth) acrylate, or triallyl (iso) cyanurate is preferable. These monomers (a1) having two or more radically polymerizable groups in the molecule may be used alone or in combination of two or more.
In one aspect of the present invention, the monomer (a1) preferably has 2 to 6 radical polymerizable groups in the molecule, and more preferably has 2 to 3 radical polymerizable groups.

(Radically polymerizable monomer containing hydrolyzable silyl group in the molecule (a2))
Examples of the radical polymerizable monomer (a2) containing a hydrolyzable silyl group in the molecule include vinylmethyldimethoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldichlorosilane, vinyltrichlorosilane and the like. Vinyl silanes; γ-acryloyloxyethylmethyldimethoxysilane, γ-acryloyloxyethyltrimethoxysilane, γ-acryloyloxyethyltriethoxysilane, γ-acryloyloxypropylmethyldimethoxysilane, γ-acryloyloxypropyltrimethoxysilane, γ- Acryloyloxypropyltriethoxysilane, γ-acryloyloxyethylmethyldichlorosilane, γ-acryloyloxyethyltrichlorosilane, γ-acryloyloxypropylmethyldichlorosilane Acrylyloxyalkylsilanes such as rhosilane, γ-acryloyloxypropyltrichlorosilane; γ-methacryloyloxyethylmethyldimethoxysilane, γ-methacryloyloxyethyltrimethoxysilane, γ-methacryloyloxyethyltriethoxysilane, γ-methacryloyloxypropylmethyl Dimethoxysilane, γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropyltriethoxysilane, γ-methacryloyloxyethylmethyldichlorosilane, γ-methacryloyloxyethyltrichlorosilane, γ-methacryloyloxypropylmethyldichlorosilane, γ-methacryloyl And methacryloyloxyalkylsilanes such as oxypropyltrichlorosilane. Of these, γ-methacryloyloxypropylmethyldimethoxysilane or γ-methacryloyloxypropyltrimethoxysilane is preferred. These radically polymerizable monomers (a2) containing a hydrolyzable silyl group in the molecule may be used alone or in combination of two or more.

[Particle (II) in which metal particles are coated with silica layer]
Particle (II) in which metal particles are coated with a silica layer refers to metal particles obtained by coating a silica layer with an average film thickness of 1.0 nm or more on the surface of metal particles. By including the particles (II), the coating film obtained from the aqueous coating material of the present invention can exhibit optical properties such as hydrophilicity and ultraviolet absorption.
In the present invention, “hydrophilic” means that the contact angle of water after 30 seconds has elapsed after dropping distilled water on the surface of the coating film in an atmosphere of 23 ° C. is 60 ° or less.
Further, “excellent in optical properties” means that the light transmittance is 90% or less when the light transmittance at a wavelength of 320 nm is measured using a spectrophotometer.

  Content of particle | grains (II) in an aqueous coating material is 0.1-13 mass parts in conversion of solid content with respect to 100 mass parts of polymers (I). If content of particle | grains (II) is 0.1 mass part or more, optical characteristics, such as the hydrophilic property of a coating film obtained and ultraviolet-ray absorption, will improve. Moreover, if the said content of particle | grains (II) is 13 mass parts or less, the hydrophilic property and ultraviolet-ray absorptivity of a coating film can be improved, without reducing the transparency of the coating film obtained. The content of the particles (II) is preferably 0.5 to 6 parts by mass with respect to 100 parts by mass of the polymer (I).

In the present invention, the “average film thickness of the silica layer” refers to a value calculated from the following formula (1) on the assumption that the obtained particles (II) are spheres.
X ³ + 3rX ² + 3r ² X-Qr / Qx · w / (100-w) r ³ = 0 (1)
The meaning of each symbol in the above formula (3) is as follows.
X: average thickness of silica layer r: radius of metal particle Qr: density of metal particle Qx: density of silica layer w: ratio (wt%) of silica layer in particle (II) (w = 100 · Mx / (Mx + Mr) ))
Mr: Weight of metal particles (Mr = Qr · Vr)
Vr: Volume of metal particles (Vr = 4/3 · πr ³ )
Mx: weight of the silica layer (Mx = Qx · Vx)
Vx: volume of the silica layer (Vx = 4/3 · π · (X + r) ³ −4 / ³ · πr ³ )
Here, the radius r of the metal particle is a catalog value or a measured value measured by a field emission scanning electron microscope or a transmission electron microscope when the metal particle used is a commercial product. When calculating the radius r of a metal particle using a field emission scanning electron microscope or a transmission electron microscope, measurement using photographic paper or image analysis software WinROOF, etc., for any 200 particles is used. Can be measured.
In addition, the weight of the metal particles can be obtained from the reference [[1] CRC Handbook of Chemistry and Physics, 83rd Edition, D.C. R. Lide, 2002, 2) “Nano-sized titanium oxide” is a density value obtained from the Japan Titanium Oxide Industry Association (2008.11.27)] or the like, or a value calculated from the radius r of the metal particles.
As a specific value, cerium oxide: 7.65 g / cm ^3, a titanium oxide (rutile type): 4.27g / cm ^3, a titanium oxide (anatase): 3.90g / cm ^3, zinc oxide: 5.6 g / Cm ³ , silica: 2.65 g / cm ³ can be exemplified. Furthermore, the ratio (wt%) of the silica layer in the particles (II) refers to a value measured by energy dispersive X-ray spectroscopy.

When the average film thickness of the silica layer is 1.0 nm or more, the particles (II) are unevenly distributed on the surface layer of the obtained coating film, and the hydrophilicity and transparency excellent in the coating film can be imparted. Here, the “surface layer of the coating film” means a layer from the interface with the air of the obtained coating film to a depth of 100 nm.
Moreover, the average film thickness of the said silica layer becomes like this. From the point of the hydrophilic property of a coating film, and transparency, Preferably it is 1.0-10.0 nm, More preferably, it is 1.0-5.0 nm.
In the present invention, “excellent in transparency” means that a haze value measured using a haze meter in accordance with JIS K7136 is 5% or less.

The type of the metal particles of the particles (II) is not particularly limited as long as it has the effect of the present invention. From the viewpoint of optical properties such as ultraviolet absorption, metals such as cerium oxide, titanium oxide, and zinc oxide are used. An oxide is preferable. These metal oxides are preferably 2 to 600 nm, more preferably 5 to 300 nm, and particularly preferably 5 from the viewpoint of setting the average particle diameter of the obtained particles (II) within a preferable range described later. ~ 100 nm.
As specific examples of these metal oxides, commercially available products can be used, for example, CE-20B (manufactured by Nissan Chemical Industries, Ltd., cerium oxide sol, average particle size: 5 nm, solid content: 20% by mass), TKS-203 (manufactured by Teika Co., Ltd., titanium oxide sol for photocatalyst, average particle size: 20 nm, solid content: 20% by mass), ZN-120 (manufactured by TECNAN, zinc oxide sol, average particle size: 15 nm, solid content: 20% by mass) can be obtained relatively easily.

  In addition, the average particle diameter of the particles (II) is preferably 2 to 600 nm, more preferably 5 to 300 nm, from the viewpoint of optical properties such as hydrophilicity, transparency, and ultraviolet absorption of the obtained coating film. Yes, particularly preferably 5 to 100 nm. Here, the average particle size of the particles (II) was determined by a dynamic light scattering method (DLS: Dynamic Light Scattering) using a particle size distribution measuring device (product name: Zetasizer Nano ZS, manufactured by Malvern). It means the Z average particle diameter of primary particles or secondary particles. Specifically, the measurement sample is prepared by adding particles (II) to distilled water at a temperature of 25 ° C. so that the particle concentration is 0.1 to 0.001% by mass. Using a sonic cleaner (product name: W-113, manufactured by Honda Electronics Co., Ltd.), after irradiating ultrasonic waves at a frequency of 28 kHz for 10 minutes, it can be calculated by measuring using the particle size distribution measuring apparatus described above. . As measurement conditions, a sample was put in a polymethyl methacrylate resin (PMMA) disposable cell and set in an apparatus, measurement temperature 25 ° C., measurement angle: 173 ° backscattering detection, measurement time: automatic, number of measurements four times. The method of calculating as an average value of is mentioned.

[Other additives]
(Surfactant (E))
In one aspect of the present invention, the aqueous coating material preferably contains a surfactant (E).
From the viewpoint of hydrophilicity and durability of the obtained coating film, the content of the surfactant (E) in the aqueous coating material is 0.01 to 5 parts by mass with respect to 100 parts by mass of the polymer (I). It is preferable that it is 2 to 4 parts by mass. Usable surfactants (E) include various anionic, cationic, or nonionic surfactants, and polymer emulsifiers. In one embodiment of the present invention, the aqueous coating material preferably contains a nonionic surfactant (E1) from the viewpoint of the hydrophilicity of the resulting coating film, and the nonionic surfactant (E1) and an anionic system are included. It is more preferable that surfactant (E2) is included.

(Nonionic surfactant (E1))
As the nonionic surfactant (E1), those having an HLB of 16 or more are more preferable.
HLB (Hydrophile-Lipophile Balance) is a hydrophilic / lipophilic balance, and is a value calculated by the Griffin method (all revised edition, introduction to surfactants, p128) obtained from the following formula (2).
Nonionic surfactant HLB = (molecular weight of hydrophilic group portion of surfactant / molecular weight of surfactant) × 20 (2)
The HLB of the nonionic surfactant (E1) is more preferably 17 or more, and more preferably 18 or more because the hydrophilicity of the resulting coating film surface is further increased.
Nonionic surfactants having an HLB of 16 or more include, for example, polyoxyalkylene alkyl ether, polyoxyalkylene alkyl phenol ether, polyoxyalkylene aryl ether, polyoxyalkylene alkyl aryl ether, sorbitan derivatives, and polyoxyalkylene aryl ether formalin. Examples include condensates and formalin condensates of polyoxyalkylene alkyl aryl ethers. Among these, polyoxyalkylene alkyl ether is particularly preferable.
Examples of the alkyl moiety of the polyoxyalkylene alkyl ether in the nonionic surfactant (E1) include a linear or branched alkyl group having 1 to 36 carbon atoms. Moreover, it is preferable that the polyoxyalkylene part of polyoxyalkylene alkyl ether is a polyoxyethylene from the point from which the coating film which has the especially outstanding hydrophilic property and antistatic property is obtained. Further, the number of repeating units of polyoxyethylene is preferably 30 or more, and more preferably 40 or more, from the viewpoint that a coating film having particularly excellent stain resistance can be obtained.

Of the nonionic surfactants of polyoxyalkylene alkyl ether, particularly preferred is a surfactant represented by the following formula (3).
R ³ O— (C ₂ H ₄ 0) _m —H (3)
(However, m is a positive integer, and R ³ is a linear or branched alkyl group having 1 to 36 carbon atoms.)
Specific examples of the nonionic surfactant represented by the formula (3) include, for example, Emulgen 1150S-60 (trade name, manufactured by Kao Corporation, R ³ : mainly an alkyl group having 11 carbon atoms, m = 50. HLB = 18.5), Emulgen 1135S-70 (trade name, manufactured by Kao Corporation, R ³ : alkyl group mainly having 11 carbon atoms, m = 35, HLB = 17.9), and the like.
The content of the nonionic surfactant (E1) in the aqueous coating material is preferably 0.01 to 3 parts by mass, and 0.1 to 2 parts by mass with respect to 100 parts by mass of the polymer (I). It is more preferable that If the said content of nonionic surfactant (E1) is 0.01 mass part or more, the hydrophilic property and transparency of the coating film obtained will improve. Moreover, if content of nonionic surfactant (E1) is 3 mass parts or less, the hydrophilicity and transparency of the coating film obtained will improve, without impairing the stability as an aqueous coating material.

(Anionic surfactant (E2))
As anionic surfactant (E2), polyoxyalkylene aryl ether sulfate ester salt, polyoxyalkylene aryl ether phosphate ester salt, polyoxyalkylene alkyl aryl ether sulfate ester salt and polyoxyalkylene alkyl aryl ether phosphate ester Surfactants such as salts can be mentioned. These anionic surfactants (E2) may be used alone or in combination of two or more.
The aforementioned sulfate ester salt includes a formalin condensate.
That is, as the anionic surfactant (E2), polyoxyalkylene aryl ether sulfate ester salt, polyoxyalkylene alkyl aryl ether sulfate ester salt, polyoxyalkylene aryl ether sulfate ester salt formalin condensate, It is preferably at least one selected from the group consisting of a formalin condensate of a sulfate ester salt of an oxyalkylene alkylaryl ether.
Specific examples of the anionic surfactant (E2) include, for example, Nucor 707SF (trade name, manufactured by Nippon Emulsifier Co., Ltd., polyoxyalkylene aryl ether sulfate ester salt), Latemul E-1000A (trade name, Kao) And a sulfate ester salt of polyoxyalkylene aryl ether).
As content of the anionic surfactant (E2) in an aqueous coating material, it is preferable that it is 1-5 mass parts with respect to 100 mass parts of polymers (I), and it is 1-3 mass parts. Is more preferable.

  In the aqueous coating material of the present invention, various pigments, antifoaming agents, pigment dispersants, leveling agents, anti-sagging agents, matting agents, UV absorbers, and light stabilizers are used to exhibit excellent performance as coating materials. Various additives such as an agent, an antioxidant, a heat resistance improver, a slip agent, an antiseptic, a plasticizer, and a film forming aid may be included. Furthermore, other water dispersible resins such as polyester resins, polyurethane resins, acrylic resins, acrylic silicone resins, silicone resins, fluorine resins, epoxy resins, water soluble resins, viscosity control agents, melamines, isocyanates A curing agent such as a kind may be mixed.

<Method for preparing aqueous coating material>
As described above, the aqueous coating material of the present invention includes the polymer (I) and the particles (II).
The aqueous coating material can be obtained, for example, by mixing a dispersion liquid of the polymer (I) obtained by the following production method and a dispersion liquid of the particles (II) so as to have a specific blending ratio. .

[Production Method of Polymer (I)]
As a method for producing the polymer (I), an emulsion polymerization method or a method of obtaining the polymer (I) by dispersing the polymer in water after solution polymerization can be employed.
In order to obtain the polymer (I) by the emulsion polymerization method, for example, in the presence of a surfactant, a mixture of the radical polymerizable monomer (A) is supplied into the polymerization system and the radical polymerization initiator (B). A known method such as a method for carrying out polymerization can be used.
As the surfactant to be used, those described in the above-mentioned surfactant (E) can be appropriately used. Moreover, as addition amount of surfactant, it is preferable that it is 0.1-10 mass parts with respect to 100 mass parts of radically polymerizable monomers (A) which comprise polymer (I). By setting the content of the surfactant to 0.1 parts by mass or more with respect to 100 parts by mass of the radical polymerizable monomer (A), the polymerization stability of the polymer (I) and the stability of the aqueous coating material Will improve. In addition, by setting the addition amount of the surfactant to 10 parts by mass or less with respect to 100 parts by mass of the radical polymerizable monomer (A), excellent stability without impairing the coating performance such as water resistance. Can be maintained. A more preferable content is 2 to 5 parts by mass.
When the polymer (I) is produced by the emulsion polymerization method, the basic compound (C) is added to the obtained dispersion of the polymer (I) to adjust the pH of the dispersion to 8.5 to 8.5. It is preferable to adjust to the range of 11.0. The pH of the dispersion is more preferably 9.0 to 10.0.

(Radical polymerization initiator (B))
As the radical polymerization initiator (B), those generally used for radical polymerization can be used. For example, persulfates such as potassium persulfate, sodium persulfate, ammonium persulfate, azobisisobutyronitrile, 2,2'-azobis (2-methylbutyronitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (4-methoxy-2,4-dimethylvaleronitrile) Oil-soluble azo compounds such as 2-phenylazo-4-methoxy-2,4-dimethylvaleronitrile; 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- Til-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 salts thereof, 2,2'-azobis [2- (3,4,5,6-tetrahydropyrimidin-2-yl) propane] and salts thereof 2,2′-azobis (1-imino-1-pyrrolidino-2-methylpropane) and its salts, 2,2′-azobis {2- [1- (2-hydroxyethyl) -2-imidazoline-2- Yl] propane} and salts thereof, 2,2′-azobis (2-methylpropionamidine) and salts thereof, 2,2′-azobis [N- (2-carboxyethyl) -2-methylpropionamidine And water-soluble azo compounds such as salts thereof; organics such as benzoyl peroxide, cumene hydroperoxide, t-butyl hydroperoxide, t-butylperoxy-2-ethylhexanoate, t-butylperoxyisobutyrate And peroxides.
The addition amount of the radical polymerization initiator (B) is usually 0.01 to 10 parts by mass with respect to 100 parts by mass of the radical polymerizable monomer (A) constituting the polymer (I). Taking the progress and reaction control into consideration, it is preferably 0.02 to 5 parts by mass.

(Basic compound (C))
Examples of the basic compound (C) 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-propyl Examples include aminoethanol, ethoxypropylamine, aminobenzyl alcohol, morpholine, sodium hydroxide, and potassium hydroxide. Among these, ammonia is preferable from the viewpoint of hydrophilicity of the obtained coating film. As a basic compound (C), 1 type may be used independently and 2 or more types may be used together.

(Molecular weight regulator (D))
When adjusting the molecular weight of the polymer (I), as the molecular weight modifier (D), mercaptans such as n-dodecyl mercaptan, t-dodecyl mercaptan, n-octyl mercaptan, n-tetradecyl mercaptan, n-hexyl mercaptan, etc. A halogen compound such as carbon tetrachloride and ethylene bromide; a known chain transfer agent such as α-methylstyrene dimer may be used. The amount of the molecular weight modifier (D) used during the production of the polymer (I) is usually 1 part by mass or less with respect to 100 parts by mass of the radical polymerizable monomer (A) constituting the polymer (I). It is preferable that

(Polyorganosiloxane polymer (X))
In one embodiment of the present invention, the radical polymerizable monomer (A) may be polymerized in an aqueous dispersion containing the polyorganosiloxane polymer (X).
Specifically, a step of preparing a polyorganosiloxane copolymer aqueous dispersion by premixing a composition containing the polyorganosiloxane polymer (X) and polymerizing the radical polymerizable monomer (A). The method of including can be illustrated.
Examples of the polyorganosiloxane polymer (X) include dimethyldialkoxysilanes such as dimethyldimethoxysilane and dimethyldiethoxysilane, hexamethylcyclotrisiloxane, octamethylcyclotetrasiloxane, decamethylcyclopentasiloxane, and dodecamethyl. It can be synthesized using dimethylsiloxane cyclic oligomers such as cyclohexasiloxane, tetradecamethylcycloheptasiloxane, dimethyl cyclic (dimethylsiloxane cyclic oligomer 3-7 mer mixture), dimethyldichlorosilane and the like as raw materials. It is preferable to use a dimethylsiloxane cyclic oligomer from the viewpoint of excellent performance such as thermal stability and cost of the obtained resin.
In one embodiment of the present invention, the polymer (I) is added to the mixture containing the polyorganosiloxane copolymer aqueous dispersion a plurality of times, preferably 2-3 times, of the radical polymerizable monomer (A). It is preferable to include a step of separately charging and copolymerizing the polyorganosiloxane copolymer and the radical polymerizable monomer (A).

[Method for preparing particles (II) in which metal particles are coated with a silica layer]
As a method for preparing the particles (II) in which the metal particles are coated with the silica layer, the metal particles themselves or colloidal metal particles are mixed with water glass, an organosilicon compound, etc. An example is a method in which an acid such as hydrochloric acid is added to produce silicic acid. In the case of an organosilicon compound, a method in which water and an organosilicon compound are hydrolyzed by a Stover method or the like (Non-patent Document 1) can be mentioned.

By performing these generation processes immediately after or simultaneously with the ultrasonic irradiation, a good dispersion of particles (II) in which the surfaces of the metal particles are coated with a silica layer can be produced.
Specifically, a metal oxide, a surfactant, an acid solution or an alkali solution, ethanol or propanol, and water are mixed to prepare an aqueous solution containing the metal oxide, and the aqueous solution is further irradiated with ultrasonic waves. Using an instrument, ultrasonic waves with a frequency of 25 k to 1 MHz are irradiated for 1 to 60 minutes. Thereafter, the aqueous solution after irradiating the ultrasonic wave is dropped into a mixture containing the organosilicon compound and the dispersion medium, and then reacted, and then the dispersion medium is removed and further filtered to prepare particles (II). can do.
The average film thickness of the silica layer can be controlled by the concentration of the organosilicon compound. That is, in order to set the average film thickness of the silica layer to 1 nm or more, the concentration of the organosilicon compound in the mixture containing the organosilicon compound is determined based on the above formula (1) based on the density and radius of the metal oxide particles. Can be judged from the amount. For example, when 0.8 g of cerium oxide having a radius of 5 nm is included, the concentration of the organosilicon compound is preferably 0.0040 mol to 0.04 mol, and more preferably 0.0048 mol to 0.0192 mol.

(Organic silicon compound)
Examples of organosilicon compounds include trimethylmethoxysilane, trimethylethoxysilane, dimethyldimethoxysilane, dimethyldiethoxysilane, methyltrimethoxysilane, tetramethoxysilane, methyltriethoxysilane, tetraethoxysilane, methyldimethoxysilane, dimethylethoxysilane, dimethyl Vinylmethoxysilane, dimethylvinylethoxysilane, methylvinyldimethoxysilane, methylvinyldiethoxysilane, diphenyldimethoxysilane, phenyltrimethoxysilane, diphenyldiethoxysilane, phenyltriethoxysilane, vinyltriethoxysilane, γ-chloropropyltrimethoxy Silane, γ-chloropropylmethyldichlorosilane, γ-chloropropylmethyldimethoxysilane, γ-aminopropy Triethoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane, γ-mercaptopropyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ -Methacryloxypropyltrimethoxysilane, γ-methacryloxypropylmethyldimethoxysilane and the like are preferably used. Of these, methyltriethoxysilane or tetraethoxysilane is preferred from the viewpoints of reactivity and dispersibility. These organosilicon compounds may be used alone or in combination of two or more.

As described above, the aqueous coating material of the present invention includes particles (II) in which metal particles are coated with a silica layer, and the amount of the particles (II) is 0 with respect to 100 parts by mass of the polymer (I). 0.1 to 13 parts by mass, and the average film thickness of the silica layer of the particles (II) is 1.0 nm or more. The aqueous coating material of the present invention preferably further contains a surfactant, and more preferably contains a surfactant and water.
The polymer (I) is more preferably an aqueous dispersion obtained by polymerizing various radical polymerizable monomers (A). Furthermore, the solid content concentration in the aqueous dispersion of the polymer (I) is preferably 20 to 70% by mass, and more preferably 30 to 60% by mass.

<Painted object>
The aqueous coating material of the present invention can be formed into a coated product by forming a film on various articles (hereinafter referred to as “base material”).
Examples of the base material include cement mortar, slate board, gypsum board, extruded board, expandable concrete, metal, glass, porcelain tile, asphalt, wood, waterproof rubber material, plastic, calcium silicate base material, polyvinyl chloride sheet, FRP (Fiber Reinforced Plastics) and the like.

Specific examples of the coated material having a coating film obtained from the aqueous coating material of the present invention include, for example, building materials, building exteriors, building interiors, window frames, window glass, structural members, plate materials, vehicle exteriors, mechanical devices, Examples include exteriors of articles, solar battery covers, tents, and greenhouses.
As a method of applying the aqueous coating material to the surface of various base materials, for example, various coating methods such as spray coating method, roller coating method, bar coating method, air knife coating method, brush coating method, dipping method, etc. may be appropriately selected. Can do.

  Moreover, after apply | coating the aqueous coating material of this invention, a coating film can be obtained by normal temperature drying or heat drying at 40-200 degreeC.

EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated in detail, this invention is not limited to these Examples.
In the present embodiment, “part” means “part by mass”. Moreover, the physical property test of the aqueous coating material in a present Example was done by the method shown below.

[Preparation of test samples for evaluation]
A coating material for test was prepared by adding 12 parts of butyl cellosolve as a film-forming aid to each aqueous coating material. After that, a polyethylene terephthalate (PET) film (manufactured by Toyobo Co., Ltd., trade name, Cosmo Shine A4100, thickness 188 μm) was coated with each paint with a bar coater # 48 and dried at 100 ° C. for 5 minutes. A test sample for evaluation was used.

[Evaluation method]
(1) Hydrophilicity Using a direct contact angle meter DM500 (manufactured by Kyowa Interface Science Co., Ltd.), 1 μL of distilled water was dropped onto a test sample for evaluation in an atmosphere at 23 ° C., and the water contact angle after 30 seconds was measured. And evaluated according to the following criteria.
“A”: Water contact angle is 40 ° or less “b”: Water contact angle is greater than 40 ° and 60 ° or less “c”: Water contact angle is greater than 60 °

(2) Transparency Using a haze meter (manufactured by Murakami Color Research Laboratory, model HM-65W), the haze of the test sample for evaluation was measured according to JIS-K7136, and evaluated according to the following criteria.
"A": Haze is 2.5% or less "b": Haze is greater than 2.5% and 5.0% or less "c": Haze is greater than 5.0%

(3) Ultraviolet Absorbance Light transmittance at a wavelength of 320 nm was measured using a spectrophotometer (U-1900 type ratio beam spectrophotometer manufactured by Hitachi High-Technologies Corporation), and evaluated according to the following criteria.
“A”: Light transmittance is 70% or less “b”: Light transmittance is greater than 70% and 90% or less “c”: Light transmittance is greater than 90%

<Production of polymer (I)>
(Production Example 1) Preparation of polyorganosiloxane polymer aqueous dispersion 98 parts of 3- to 7-mer mixture of cyclic dimethylsiloxane oligomer and γ-methacryloyloxypropylmethyldimethoxysilane (containing hydrolyzable silyl group in the molecule) 2 parts of radically polymerizable monomer (a2)), 310 parts of deionized water and 0.7 part of sodium dodecylbenzenesulfonate were premixed with a homomixer and 200 kg / cm ² using a pressure type homogenizer. It was forcibly emulsified with pressure to obtain a pre-emulsion as a raw material.
Next, 90 parts of water and 10 parts of dodecylbenzenesulfonic acid were charged into a flask equipped with a stirrer, a reflux condenser, a temperature control device and a dropping pump, and while maintaining the internal temperature of the flask at 85 ° C. while stirring, The pre-emulsion was added dropwise over 4 hours.
After completion of the dropwise addition, polymerization was further carried out for 1 hour, the mixture was cooled, a sodium hydroxide solution in which 1.5 parts of sodium hydroxide was dissolved in 30 parts of deionized water was added, and an aqueous dispersion of polyorganosiloxane copolymer ( SiEm) was prepared. The solid content of the polyorganosiloxane copolymer aqueous dispersion was 18% by mass.

(Production Example 2) Production of polymer (I-1) SiEm (solid content: 18%) 5 obtained in Production Example 1 in a flask equipped with a stirrer, a reflux condenser, a temperature controller, and a dropping pump 5 Parts, 49 parts deionized water, 2.5 parts Newcol 707SF (trade name, manufactured by Nippon Emulsifier Co., Ltd., anionic surfactant (E2)), 6 parts methyl methacrylate, 24 parts 2-ethylhexyl acrylate, glycidyl A raw material mixture composed of a radical polymerizable monomer mixture (AI) in which 3 parts of methacrylate, 1 part of 2-hydroxyethyl methacrylate and 1 part of triallyl cyanurate were mixed was charged, and the internal temperature of the flask was raised to 40 ° C. After that, 0.0002 part of iron (II) sulfate heptahydrate, 0.00027 part of ethylenediaminetetraacetic acid, 0.12 part of sodium L-ascorbate, A reducing agent aqueous solution (YI) mixed with 1 part of distilled water, 0.02 part of t-butyl hydroperoxide (trade name: Perbutyl H69, manufactured by NOF Corporation) and 1 part of deionized water were mixed. A radical polymerization initiator aqueous solution (BI) was added. After confirming the peak top temperature due to the polymerization exotherm, the internal temperature of the flask was maintained at 75 ° C.
Next, 0.5 hours after the addition of the reducing agent aqueous solution (Y-I), 36.3 parts of methyl methacrylate, 22.33 parts of n-butyl methacrylate, 3.2 parts of 2-ethylhexyl acrylate, acrylic acid 1 A radical polymerizable monomer mixture (A-II) in which .67 parts, 1.5 parts of diacetone acrylamide, 4.2 parts of New Coal 707SF, and 20 parts of deionized water were added dropwise over 2.75 hours. Further, from an addition pump different from the radical polymerizable monomer mixture (A-II), 0.03 parts of perbutyl H69 and 5 parts of deionized water were mixed to form a radical polymerization initiator aqueous solution (B-II). ) Was simultaneously added dropwise over 3 hours. During the dropping, the internal temperature of the flask was maintained at 75 ° C., and after completion of the dropping, the temperature was maintained at 75 ° C. for 1 hour.
Thereafter, the flask was cooled to 40 ° C., 1.45 parts of 28% aqueous ammonia was added, and then an adipic acid dihydrazide aqueous dispersion in which 0.7 parts of adipic acid dihydrazide and 1.5 parts of deionized water were mixed, and the surface activity. As an aqueous agent solution, 5.0 parts of New Coal 707SF were sequentially added to obtain an aqueous dispersion of polymer (I-1). The solid content of the polymer (I-1) was 50.6%.

Production Example 3 Production of Polymer (I-2) Table 1 shows the amount of SiEm added, the radical polymerizable monomer mixture (AI), and the radical polymerizable monomer mixture (A-II). An aqueous dispersion of polymer (I-2) was obtained in the same manner as polymer (I-1) except that the procedure was changed as described above. The solid content of the polymer (I-2) was 50.5% by mass.

(Production Example 4) Production of polymer (I-3) SiEm (solid content: 18%) 5 obtained in Production Example 1 was added to a flask equipped with a stirrer, a reflux condenser, a temperature controller, and a dropping pump. , 47 parts of deionized water, 3.5 parts of New Coal 707SF, and the radical polymerizable monomer mixture (AI) shown in Table 1 were prepared, and the temperature inside the flask was raised to 40 ° C. The reducing agent aqueous solution (YI) and radical polymerization initiator aqueous solution (BI) used in Example 1 were added. After confirming the peak top temperature due to the polymerization exotherm, the internal temperature of the flask was maintained at 75 ° C.
Next, 0.5 hours after adding the reducing agent aqueous solution (Y-1), 21 parts of deionized water, 3.6 parts of Neucor 707SF and the radical polymerizable monomer mixture (A-II) shown in Table 1 were used. The raw material mixture consisting of 4 parts of deionized water, 0.6 part of New Coal 707SF, and the radical polymerizable monomer mixture (A-III) shown in Table 1 was added dropwise over 2.5 hours. Was added dropwise over 0.25 hours. Furthermore, the radical polymerization initiator aqueous solution (B-II) used in Production Example 1 was simultaneously dropped over 3.25 hours from a dropping pump different from these raw material mixtures. During the dropwise addition, the internal temperature of the flask was maintained at 75 ° C, and after completion of the dropwise addition, the temperature was maintained at 75 ° C for 0.5 hours.
Thereafter, 0.85 part of 28% ammonia water was added and held at 75 ° C. for 1 hour, then cooled to 40 ° C., 4.0 parts of Neucor 707SF was added as a surfactant aqueous solution, and the polymer (I- An aqueous dispersion of 3) was obtained. The solid content of the polymer (I-3) was 50.0%.

(Production Example 5) Production of polymer (I-4) In a flask equipped with a stirrer, a reflux condenser, a temperature controller, and a dropping pump, 65 parts deionized water, 0.8 part Newcor 707SF, and Table 1 A radical polymerization initiator aqueous solution (B-) containing 1 part of ammonium sulfate and 5 parts of deionized water after charging the radical polymerizable monomer mixture (AI) shown in FIG. 2) was added. After confirming the peak top temperature due to the polymerization exotherm, the internal temperature of the flask was maintained at 80 ° C.
Next, a raw material mixture composed of 18 parts of deionized water, 5.7 parts of New Coal 707SF and the radical polymerizable monomer mixture (A-II) shown in Table 1 was added dropwise over 1.5 hours. Part, 5.7 parts Newcol 707SF and the radical polymerizable monomer mixture (A-III) shown in Table 1 were added dropwise over 1.5 hours. During the dropping, the internal temperature of the flask was kept at 80 ° C., and after the dropping was kept at 80 ° C. for 1 hour.
Thereafter, the mixture was cooled to 40 ° C., and 2.1 parts of 28% ammonia water was added to obtain an aqueous dispersion of polymer (I-4). The solid content of the polymer (I-4) was 46.5%.

(Production Example 6) Production of polymer (I-5) Except for changing radically polymerizable monomer mixture (AI) and radically polymerizable monomer mixture (A-II) as shown in Table 1. Obtained an aqueous dispersion of polymer (I-5) in the same manner as polymer (I-1). The solid content of the polymer (I-5) was 50.2% by mass.

The abbreviations in Table 1 indicate the following compounds.
MMA: methyl methacrylate 2-EHA: 2-ethylhexyl acrylate GMA: glycidyl methacrylate 2-HEMA: 2-hydroxyethyl methacrylate TAC: triallyl cyanurate n-BA: n-butyl acrylate n-BMA: n-butyl methacrylate AA: acrylic Acid DAAm: Diacetone acrylamide AMA: Allyl methacrylate MAA: Methacrylic acid SZ-6030: γ-Methacryloyloxypropyltrimethoxysilane (trade name, manufactured by Toray Dow Corning Silicone Co., Ltd.)

(Production Example 7) Production of particles (II-1) in which metal particles are coated with a silica layer Cerium oxide sol (average particle size: 5 nm, trade name: CE20B, manufactured by Nissan Chemical Industries, Ltd.) 4 parts, Newcor 707SF (Trade name, manufactured by Nippon Emulsifier Co., Ltd.) 0.025 parts, 28% ammonia water 50 parts, ethanol 900 parts, deionized water 360 parts are mixed to prepare a first raw material mixture, and an ultrasonic irradiator ( Using a product name: ASU-10D, manufactured by ASONE Co., Ltd., ultrasonic irradiation was performed at 23 kHz for 10 minutes, and then ultrasonic irradiation was performed at 43 kHz for 10 minutes.
Thereafter, 2 parts of tetraethoxysilane (manufactured by Wako Pure Chemical Industries, Ltd.) and 180 parts of ethanol are mixed to prepare a second raw material mixture, and the second raw material mixture is added to the first raw material mixture over 10 minutes at room temperature. The solution was added dropwise and then stirred for 3 hours.
Subsequently, after heating at 70 to 80 ° C. to distill off ethanol, the solution was concentrated using an ultrafiltration device (manufactured by Asahi Kasei Chemicals Co., Ltd., pencil-type module and tabletop filtration unit SIP0013), and covered with a silica layer. Particles (II-1) were obtained. The solid content of the particles (II-1) was 1.57%.

(Production Examples 8 to 12) Production of Particles (II-2) to (II-6) Particles were produced in the same manner as in Production Example 6 except that the first raw material mixture and the second raw material mixture were changed as shown in Table 2. (II-2) to (II-6) were obtained.

Abbreviations in Table 2 indicate the following compounds: CE-20B: cerium oxide sol (average particle size: 10 nm), manufactured by Nissan Chemical Industries, Ltd. TKS-203: titanium oxide sol for photocatalyst (average particle size: 40 nm), Taca ZN-120: Zinc oxide sol (average particle size: 30 nm), manufactured by TECNAN

[Example 1]
(Adjustment of water-based coating material)
With respect to the obtained aqueous dispersion of polymer (I), particles (II-1) in which metal particles are coated with a silica layer, and Emulgen 1150S-60 (trade name, Kao) as a nonionic surfactant (E1) An aqueous coating material was prepared by adding 1 part by mass to 100 parts by mass of the polymer (I). Samples for evaluation tests were prepared from the obtained aqueous coating materials, and the hydrophilicity, transparency, and ultraviolet absorption of the coating film were evaluated.

[Examples 2 to 13, Comparative Examples 1 and 2]
An aqueous coating material was prepared in the same manner as in Example 1 except that the polymer (I), particles (II), and other inorganic particles were changed as shown in Tables 3 and 4. A sample for evaluation test was prepared from the obtained aqueous coating material, and the same measurement and evaluation as in Example 1 were performed.

  As shown in Table 3 and Table 4, the coating films obtained from the aqueous coating materials of Examples 1 to 13 of the present invention had excellent hydrophilicity, transparency, and ultraviolet absorption.

  On the other hand, in the aqueous coating material of Comparative Example 1, the content of the particles (II) was an excess of 15 parts by mass with respect to 100 parts by mass of the polymer (I). It was inferior. Since the average film thickness of the silica layer of particle | grains (II) was less than 1.0 nm, the comparative example 2 was inferior to hydrophilicity.

  The coating film obtained from the aqueous coating material of the present invention has excellent hydrophilicity, transparency, and optical properties. Therefore, it can be used for various coating applications such as protection of building bodies, civil engineering structures, and the like, which is extremely useful industrially.

Claims (11)

  An aqueous coating material comprising a polymer (I) and particles (II) in which metal particles are coated with a silica layer, wherein the particles (II) are reduced to 0 with respect to 100 parts by mass of the polymer (I). An aqueous coating material containing 1 to 13 parts by mass and having an average film thickness of the silica layer of the particles (II) of 1.0 nm or more.   The aqueous coating material according to claim 1, wherein the average particle diameter of the particles (II) is 2 to 600 nm.   The aqueous coating material according to claim 1, wherein the metal particles are a metal oxide.   The aqueous coating material according to claim 3, wherein the metal oxide is at least one selected from the group consisting of cerium oxide, zinc oxide, and titanium oxide. The aqueous coating material according to any one of claims 1 to 4, further comprising a nonionic surfactant,
An aqueous coating material comprising 0.01 to 3 parts by mass of the nonionic surfactant with respect to 100 parts by mass of the polymer (I).   The aqueous coating material according to claim 5, wherein the nonionic surfactant has an HLB of 16 or more. The aqueous coating material according to any one of claims 1 to 6, further comprising an anionic surfactant,
The anionic surfactant is a polyoxyalkylene aryl ether sulfate ester salt, a polyoxyalkylene alkyl aryl ether sulfate ester salt, a polyoxyalkylene aryl ether sulfate ester formalin condensate, and a polyoxyalkylene alkyl aryl ether. An aqueous coating material, which is at least one anionic surfactant selected from the group consisting of a formalin condensate of a sulfate ester salt.   The aqueous coating material according to any one of claims 1 to 7, wherein the polymer (I) is a copolymer obtained by polymerizing at least two types of radically polymerizable monomers (A).   The radical polymerizable monomer (A) is a monomer (a1) having two or more radical polymerizable groups in the molecule, and a radical polymerizable monomer containing a hydrolyzable silyl group in the molecule ( The aqueous coating material according to claim 8, comprising at least one monomer selected from the group consisting of a2).   The coated article which has a coating film obtained from the aqueous coating material as described in any one of Claims 1-9.   The coated object according to claim 10, wherein the water contact angle of the surface of the painted object is 60 degrees or less.