JP5280120B2 - Multilayer coating - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-layer coating film, which can be formed using a water-based composition and by which not only fouling resistance, but also sufficient weatherability can be obtained even when it is directly formed on the surface of an organic base material. <P>SOLUTION: A multi-layer coating film 1 incldues an undercoat layer 11 and a top coat layer 12 provided on the undercoat layer 11. The undercoat layer 11 is a film formed by drying a coating film of an undercoating composition (I) that contains polymer emulsion particles (A) obtained by a method involving the step of polymerizing a vinyl monomer and a hydrolytic silicon compound separately. The top coat layer 12 is a film formed by drying a coating film of a top coating composition (II) that contains metal oxide particles (B) having photocatalytic activity, polymer emulsion particles (C) obtained by a method involving the step of polymerizing a vinyl monomer and a hydrolytic silicon compound separately, and colloidal silica (D). <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a multilayer coating film comprising an undercoat layer and an overcoat layer.

  Outdoor structures such as building exteriors, bridges, and tanks are contaminated by combustion products such as dust and exhaust gas contained in the air, dirt eluted from the sealing material, and pollutants discharged from the building outlet. Is done. These stains are light black and significantly detract from the beauty of buildings and outdoor structures. The cleaning is a high-altitude work and a heavy labor.

  Therefore, Patent Document 1 and Patent Document 2 propose a purification method using a building material for an outer wall having a surface layer portion containing a photocatalyst and having a surface that is self-cleaned (self-cleaning) by rain. By providing a surface layer containing a photocatalyst, the surface of the surface layer exhibits hydrophilicity in response to photoexcitation of the photocatalyst, so that deposits and contaminants are deposited by raindrops when the surface of the exterior wall building material is exposed to rain. It can be washed away. However, in this method, since the photocatalyst contained in the surface layer part has organic decomposability, the base material deteriorates when the layer in contact with the surface layer part is an organic base material such as a plastic molded body, a film, or an organic coating film. In some cases, the weather resistance was not good, and the appearance deteriorated.

In relation to this problem, Patent Document 3 discloses a coating film in which the photocatalyst concentration is small in the vicinity of the interface in contact with the organic base and is largely distributed in the vicinity of the coating surface so that the photocatalyst is inclined and distributed in the depth direction from the surface. A method of forming a (self-gradient coating) is disclosed. It is described that the photocatalyst does not deteriorate the interface with the organic substrate, has excellent weather resistance, and has high photocatalytic activity. Patent Document 4 describes an antifouling coating material composition comprising a photocatalyst, a silicon emulsion, a surfactant, and water. Patent Document 4 also describes an example of coating on an organic coating plate (thermosetting acrylic resin).
Japanese Patent No. 2756474 Japanese Patent No. 3414365 International Publication No. 00/30747 Pamphlet JP-A-10-316937

  However, since the method of Patent Document 3 uses a combination of a photocatalyst modified with a silicone compound having a low surface energy and a binder having a higher surface energy, it may be difficult to make the composition for forming a coating water-based. It was. Further, when a coating material containing a photocatalyst is applied on a normal organic paint as in Patent Document 4, the base material is likely to deteriorate, so that the weather resistance is not always sufficient.

  Therefore, an object of the present invention is to be able to be formed using an aqueous composition, and to obtain not only contamination resistance but also sufficient weather resistance even when formed directly on the surface of an organic substrate. It is providing the multilayer coating film which can be manufactured.

  The present invention relates to a multilayer coating film comprising an undercoat layer and an overcoat layer provided on the undercoat layer. The undercoat layer comprises a polymer emulsion particle (A) obtained by a method comprising a step of polymerizing a vinyl monomer and a hydrolyzable silicon compound in the presence of water and an emulsifier, respectively. It is a film | membrane formed by drying the coating film. The topcoat layer is a polymer emulsion particle (B) obtained by a method comprising a step of polymerizing a metal monomer particle (B) having photocatalytic activity and a vinyl monomer and a hydrolyzable silicon compound in the presence of water and an emulsifier, respectively. C) and a film formed by drying a coating film of a coating composition (II) for topcoat containing colloidal silica (D).

  The undercoat layer and the overcoat layer constituting the multilayer coating film according to the present invention can be formed using an aqueous composition containing polymer emulsion particles. And even if a multilayer coating film is formed on the surface of the organic substrate by combining the specific undercoat layer and the overcoat layer, still another protective layer is provided between the undercoat layer and the substrate. Excellent weather resistance can be obtained even without providing. Furthermore, since the overcoat layer contains colloidal silica together with metal oxide particles having photocatalytic activity, it is possible to maintain excellent antifouling properties over a long period of time, including when the surface is not irradiated with light. is there.

  The polymer emulsion particles (A) polymerize a vinyl monomer and a hydrolyzable silicon compound at a mass ratio of vinyl monomer / hydrolyzable silicon compound = 95/5 to 50/50 in the presence of water and an emulsifier. It is preferable that it is obtained by the method including the process to make.

  The undercoating coating composition (I) preferably further contains an ultraviolet absorber and / or a light stabilizer.

  The polymer emulsion particles (C) preferably have a core / shell structure.

  In the presence of water and an emulsifier, the polymer emulsion particles (C) comprise a vinyl monomer and a hydrolyzable silicon compound containing an amide group-containing vinyl monomer having a secondary amide group and / or a tertiary amide group. It is preferably obtained by a method including a step of polymerizing. In this case, the mass ratio of the amide group-containing vinyl monomer and the polymer emulsion particles (C) is amide group-containing vinyl monomer / polymer emulsion particles (C) = 10/90 to 70/30. Is preferred.

  The multilayer coating film of the present invention can be formed using a water-based composition, and even when it is directly formed on the surface of an organic substrate, it has not only stain resistance but also sufficient weather resistance. It is possible.

  Hereinafter, a preferred embodiment of the present invention (hereinafter may be abbreviated as “this embodiment”) will be described in detail. However, the present invention is not limited to the following embodiments.

  FIG. 1 is a cross-sectional view showing an embodiment of a multilayer coating film. A multilayer coating film 1 shown in FIG. 1 includes an undercoat layer 11 that directly covers the surface of a substrate 2 and an overcoat layer 12 provided on the undercoat layer. The undercoat layer 11 and the overcoat layer 12 are formed using the undercoat coating composition (I) and the overcoat coating composition (II), respectively.

  The undercoat coating composition (I) is an aqueous composition containing polymer emulsion particles (A) and water.

  The polymer emulsion particles (A) can be obtained by a method including a step of polymerizing the vinyl monomer (a1) and the hydrolyzable silicon compound (a2) simultaneously or separately in the presence of water and an emulsifier. The polymer emulsion particles (A) obtained by such a method are a composite of the polymerization product of the vinyl monomer (a1) and the polymerization product of the hydrolyzable silicon compound (a2). . The mass ratio ((a1) / (a2)) of the hydrolyzable silicon compound (a2) to the vinyl monomer (a1) is preferably 95/5 to 50/50.

Examples of the hydrolyzable silicon compound (a2) include a compound represented by the following formula (1), a condensation product thereof, and a silane coupling agent.
SiWxRy (1)

  In formula (1), W represents an alkoxy group having 1 to 20 carbon atoms, a hydroxyl group, an acetoxy group having 1 to 20 carbon atoms, a halogen atom, a hydrogen atom, an oxime group having 1 to 20 carbon atoms, an enoxy group, an aminoxy group, and an amide. Represents at least one group selected from the group; R is a linear or branched alkyl group having 1 to 30 carbon atoms, a cycloalkyl group having 5 to 20 carbon atoms, and an alkyl group having 1 to 20 carbon atoms or an alkoxy group having 1 to 20 carbon atoms, or It represents at least one hydrocarbon group selected from aryl groups having 6 to 20 carbon atoms which may be substituted with a halogen atom. x is an integer from 1 to 4, and y is an integer from 0 to 3. x + y = 4. As W, a silicon alkoxide having at least one alkoxy group is preferable.

  The silane coupling agent represents a hydrolyzable silicon compound in which a functional group having reactivity with an organic substance such as a vinyl group, an epoxy group, an amino group, a methacryl group, a mercapto group, or an isocyanate group exists in the molecule.

  Specific examples of the silicon alkoxide and the silane coupling agent include tetraalkoxysilanes such as tetramethoxysilane, tetraethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane, and tetra-n-butoxysilane; methyltrimethoxy Silane, methyltriethoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, n-propyltrimethoxysilane, n-propyltriethoxysilane, isopropyltrimethoxysilane, isopropyltriethoxysilane, n-butyltrimethoxysilane, n- Butyltriethoxysilane, n-pentyltrimethoxysilane, n-hexyltrimethoxysilane, n-heptyltrimethoxysilane, n-octyltrimethoxysilane, vinyltrimethoxysilane, Vinyltriethoxysilane, allyltrimethoxysilane, cyclohexyltrimethoxysilane, cyclohexyltriethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, 3-chloropropyltrimethoxysilane, 3-chloropropyltriethoxysilane, 3, 3, 3-trifluoropropyltrimethoxysilane, 3,3,3-trifluoropropyltriethoxysilane, 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, 2-hydroxyethyltrimethoxysilane, 2-hydroxyethyl Triethoxysilane, 2-hydroxypropyltrimethoxysilane, 2-hydroxypropyltriethoxysilane, 3-hydroxypropyltrimethoxysilane, 3-hydroxypropyltriethoxy Silane, 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-isocyanatopropyltrimethoxysilane, 3-isocyanatopropyltriethoxysilane, 3-glycidoxypropyltrimethoxysilane, 3-glycid Xylpropyltriethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, 2- (3,4-epoxycyclohexyl) ethyltriethoxysilane, 3- (meth) acryloxypropyltrimethoxysilane, 3- (Meth) Atacryloxypropyltriethoxysilane, 3- (meth) acryloxypropyltri-n-propoxysilane, 3- (meth) acryloxypropyltriisopropoxysilane, 3-ureidopropyltrimethoxysilane, 3 Trialkoxysilanes such as ureidopropyltriethoxysilane; dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, di-n-propyldimethoxysilane, di-n-propyldiethoxysilane, diisopropyldimethoxysilane Diisopropyldiethoxysilane, di-n-butyldimethoxysilane, di-n-butyldiethoxysilane, di-n-pentyldimethoxysilane, di-n-pentyldiethoxysilane, di-n-hexyldimethoxysilane, di- n-hexyldiethoxysilane, di-n-heptyldimethoxysilane, di-n-heptyldiethoxysilane, di-n-octyldimethoxysilane, di-n-octyldiethoxysilane, di-n-cyclohexyldimethoxy Dialkoxysilanes such as silane, di-n-cyclohexyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane; monoalkoxysilanes such as trimethylmethoxysilane and trimethylethoxysilane There can be mentioned. These silicon alkoxides and silane coupling agents can be used alone or in admixture of two or more.

  When the silicon alkoxide or silane coupling agent is used in the form of a condensation product, the weight average molecular weight in terms of polystyrene of the condensation product is preferably 200 to 5,000, more preferably 300 to 1,000.

  Dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, di-n-propyldimethoxysilane, di-n-propyldiethoxysilane, diisopropyldimethoxysilane, diisopropyldiethoxysilane, di-n-butyldimethoxy Silane, di-n-butyldiethoxysilane, di-n-pentyldimethoxysilane, di-n-pentyldiethoxysilane, di-n-hexyldimethoxysilane, di-n-hexyldiethoxysilane, di-n-heptyl Dimethoxysilane, di-n-heptyldiethoxysilane, di-n-octyldimethoxysilane, di-n-octyldiethoxysilane, di-n-cyclohexyldimethoxysilane, di-n-cyclohexyldiethoxysilane, diphenyldimethyl It is preferable for issuing the flexibility of the coating film to use a dialkoxysilane selected from Kishishiran and diphenyl diethoxy silane and other alkoxysilanes.

  The hydrolyzable silicon compound (a2) may contain a silane coupling agent having a vinyl group. It is possible to generate a chemical bond by copolymerization of a silane coupling agent having a vinyl group and the vinyl monomer (a1). When the silane coupling agent having a vinyl group is used alone or mixed or complexed with the above-described silicon alkoxide, silane coupling agent, and their condensation products, the polymer emulsion particles (A) are formed. The polymerization product of the hydrolyzable silicon compound (a2) and the polymerization product of the vinyl monomer (a1) can be combined by chemical bonding. Compounding makes it excellent in weather resistance.

  The silane coupling agent having a vinyl group is preferably 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane, 3 -(Meth) acryloxypropyltri-n-propoxysilane, 3- (meth) acryloxypropyltriisopropoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane and 2-trimethoxysilylethyl vinyl ether One or more selected from the group.

  When the silane coupling agent having a vinyl group is used as the hydrolyzable silicon compound (a2), the blending amount is 0.01 to 10% by mass with respect to the polymer emulsion particles (A). From the aspect, it is preferable.

  The undercoat layer formed using the undercoat coating composition (I) containing the polymer emulsion particles (A) comprises a metal oxide particle (B) having photocatalytic activity thereon and the overcoat coating composition Even when (II) is applied, a coating film excellent in weather resistance, strength, and the like can be formed.

  The vinyl monomer (a1) used for producing the polymer emulsion particles (A) is selected from, for example, acrylic acid esters, methacrylic acid esters, aromatic vinyl compounds, and vinyl cyanides. Vinyl monomers contain functional groups such as carboxyl group-containing vinyl monomers, hydroxyl group-containing vinyl monomers, epoxy group-containing vinyl monomers, carbonyl group-containing vinyl monomers, anionic vinyl monomers It may contain a monomer.

  Examples of (meth) acrylic acid esters include (meth) acrylic acid alkyl esters having 1 to 50 carbon atoms in the alkyl portion, and (poly) oxyethylene di (meth) acrylates having 1 to 100 ethylene oxide groups. Is mentioned. Specific examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and methyl (meth) acrylate. Examples include cyclohexyl, cyclohexyl (meth) acrylate, lauryl (meth) acrylate, dodecyl (meth) acrylate, and the like. Specific examples of (poly) oxyethylene di (meth) acrylate include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, diethylene glycol methoxy (meth) acrylate, tetraethylene glycol di (meth) acrylate Etc.

  In the present specification, (meth) acryl is a simple description of methacryl or acryl.

  The amount of the (meth) acrylic acid ester used is preferably 0 to 99.9% by mass, more preferably 5 to 80% by mass, based on the entire vinyl monomer (a1), as one or a mixture of two or more. is there.

  Examples of the carboxyl group-containing vinyl monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid and maleic anhydride, and dibasic acid half compounds such as itaconic acid, maleic acid and fumaric acid. Examples include esters. By using a carboxylic acid group-containing vinyl monomer, a carboxyl group can be introduced into the polymer emulsion particles (A), improving the stability as an emulsion, and having a resistance to dispersion and destruction from the outside. It is possible to have it. At this time, a part or all of the introduced carboxyl group can be neutralized with amines such as ammonia, triethylamine and dimethylethanolamine, sodium hydroxide, potassium hydroxide and the like.

  The used amount of the carboxyl group-containing vinyl monomer is preferably 0.1 to 10% by mass, more preferably 0.1 to 10% by mass, based on the whole vinyl monomer (a1), as one or a mixture of two or more. 5% by mass.

  Examples of the hydroxyl group-containing vinyl monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-hydroxybutyl. Hydroxyalkyl esters of (meth) acrylic acid such as (meth) acrylate and 4-hydroxybutyl (meth) acrylate, di-2-hydroxyethyl fumarate, mono-2-hydroxyethyl monobutyl fumarate, allyl alcohol and ethylene oxide (Poly) oxyethylene mono (meth) acrylate having 1 to 100 groups, (poly) oxypropylene mono (meth) acrylate having 1 to 100 propylene oxide groups, and “Placcel FM, FA” monomer" Daicel Chemical Industries of Ltd., trade name of caprolactone addition monomer) and other alpha, and the like hydroxyalkyl esters of β- ethylenically unsaturated carboxylic acid. Specific examples of the (poly) oxyethylene (meth) acrylate include ethylene glycol (meth) acrylate, ethylene glycol methoxy (meth) acrylate, diethylene glycol (meth) acrylate, diethylene glycol methoxy (meth) acrylate, (meth ) Tetraethylene glycol acrylate, tetraethylene glycol methoxy (meth) acrylate, and the like. Specific examples of (poly) oxypropylene (meth) acrylate include propylene glycol (meth) acrylate, propylene glycol methoxy (meth) acrylate, dipropylene glycol (meth) acrylate, dimethoxy meth (meth) acrylate. Examples include propylene glycol, tetrapropylene glycol (meth) acrylate, and tetrapropylene glycol methoxy (meth) acrylate. By using a hydroxyl group-containing vinyl monomer, it is possible to improve the water dispersion stability of the polymer emulsion particles (A).

  The amount of the hydroxyl group-containing vinyl monomer described above is preferably 0.1 to 50% by mass, more preferably 0.1%, based on the entire vinyl monomer (a1) as one or a mixture of two or more. -10 mass%.

  Examples of the glycidyl group-containing vinyl monomer include glycidyl (meth) acrylate, allyl glycidyl ether, and allyl dimethyl glycidyl ether. When a glycidyl group-containing vinyl monomer or a carbonyl group-containing vinyl monomer is used, the polymer emulsion particles (A) are reactive and crosslinked with hydrazine derivatives, carboxylic acid derivatives, isocyanate derivatives, etc. It is possible to form a coating film having excellent properties.

  The amount of the glycidyl group-containing vinyl monomer or the carbonyl group-containing vinyl monomer is preferably 0 to 50% by mass with respect to the entire vinyl monomer (a1).

  Specific examples of vinyl monomers other than the above include olefins such as (meth) acrylamide, ethylene, propylene, isobutylene, dienes such as butadiene, vinyl chloride, vinylidene chloride, vinyl fluoride, tetrafluoroethylene, chloro Haloolefins such as trifluoroethylene, vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl benzoate, vinyl pt-butylbenzoate, vinyl pivalate, vinyl 2-ethylhexanoate, vinyl versatate, laurin Carboxylic acid vinyl esters such as vinyl acid, isopropenyl acetate, isopropenyl carboxylic acid such as isopropenyl acetate, vinyl ethers such as ethyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether, styrene, vinyl Aromatic vinyl compounds such as toluene, allyl esters such as allyl acetate and allyl benzoate, allyl ethers such as allyl ethyl ether and allyl phenyl ether, and 4- (meth) acryloxy-2,2,6,6,- Tetramethylpiperidine, 4- (meth) acryloxy-1,2,2,6,6, -pentamethylpiperidine, perfluoromethyl (meth) acrylate, perfluoropropyl (meth) acrylate, perfluoropropylmethyl (meth) Examples thereof include acrylate, vinylpyrrolidone, trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate, and the like, and combinations thereof.

  In the polymerization of the vinyl monomer (a1), a chain transfer agent may be used for the purpose of controlling the molecular weight of the polymer. Examples of such chain transfer agents include alkyl mercaptans such as n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan; aromatic mercaptans such as benzyl mercaptan and dodecyl benzyl mercaptan; thiocarboxylic acids or their salts Alternatively, alkyl esters thereof, or polythiols, diisopropylxanthogen disulfide, di (methylenetrimethylolpropane) xanthogen disulfide and thioglycol, and allyl compounds such as α-methylstyrene dimer can be used.

  The amount of these chain transfer agents used is preferably 0.001 to 30% by mass, more preferably 0.05 to 10% by mass, based on the total vinyl monomer.

  Examples of emulsifiers that can be used in the synthesis of the polymer emulsion particles (A) include alkylbenzenesulfonic acid, alkylsulfonic acid, alkylsulfosuccinic acid, polyoxyethylene alkylsulfuric acid, polyoxyethylene alkylarylsulfuric acid, and polyoxyethylene. Acidic emulsifiers such as distyryl phenyl ether sulfonic acid, alkali metal (Li, Na, K, etc.) salts of acidic emulsifiers, ammonium salts of acidic emulsifiers, anionic surfactants such as fatty acid soaps, alkyl trimethyl ammonium bromide, alkyl Quaternary ammonium salts such as pyridinium bromide, imidazolinium laurate, pyridinium salts, imidazolinium salt type cationic surfactants, polyoxyethylene alkyl aryl ethers, polyoxyethylene sorbita Fatty acid esters, polyoxyethylene polyoxypropylene block copolymers can be exemplified reactive emulsifier or the like having a nonionic surface active agent and a radical polymerizable double bond polyoxyethylene distyryl phenyl ether.

  Among these emulsifiers, when a reactive emulsifier having a radical polymerizable double bond is selected, the water dispersion stability of the polymer emulsion particles (A) becomes very good and the polymer emulsion particles (A The undercoat layer 11 formed by the coating composition containing) is preferable because it is superior in water resistance, chemical resistance, strength, and the like.

  Examples of the reactive emulsifier having a radical polymerizable double bond include a vinyl monomer having a sulfonic acid group or a sulfonate group, a vinyl monomer having a sulfate group, alkali metal salts and ammonium salts thereof, poly Examples include vinyl monomers having a nonionic group such as oxyethylene, and vinyl monomers having a quaternary ammonium salt.

  As a specific example of the reactive emulsifier, taking a vinyl monomer salt having a sulfonic acid group or a sulfonate group as an example, it has a radical polymerizable double bond, and a part of the sulfonic acid group is an ammonium salt. An alkyl group having 1 to 20 carbon atoms, an alkyl ether group having 2 to 4 carbon atoms, a polyalkyl ether group having 2 to 4 carbon atoms, an aryl group having 6 or 10 carbon atoms, substituted with a sodium salt or a potassium salt, and It is a compound having a substituent selected from the group consisting of a succinic acid group, or a vinyl sulfonate compound having a vinyl group to which a group which is an ammonium salt, sodium salt or potassium salt of a sulfonic acid group is bonded. The vinyl monomer having a sulfate ester group is an alkyl having 1 to 20 carbon atoms, which has a radical polymerizable double bond and a part of the sulfate ester group is substituted with an ammonium salt, a sodium salt or a potassium salt. A compound having a substituent selected from the group consisting of a group, an alkyl ether group having 2 to 4 carbon atoms, a polyalkyl ether group having 2 to 4 carbon atoms, and an aryl group having 6 or 10 carbon atoms.

  Specific examples of the compound having a succinic acid group in which a part of the sulfonic acid group is substituted with an ammonium salt, a sodium salt or a potassium salt include allylsulfosuccinate. Specific examples thereof include, for example, Eleminol JS-2 (trade name) (manufactured by Sanyo Kasei Co., Ltd.), Latemuru S-120, S-180A or S-180 (trade name) (manufactured by Kao Corporation), and the like. Can be mentioned.

  Moreover, as a specific example of a compound having a C2-C4 alkyl ether group or a C2-C4 polyalkyl ether group in which a part of the sulfonic acid group is substituted with ammonium salt, sodium salt or potassium salt For example, Aqualon HS-10 or KH-1025 (trade name) (Daiichi Kogyo Seiyaku Co., Ltd.), Adekaria soap SE-1025N or SR-1025 (trade name) (Asahi Denka Kogyo Co., Ltd.), etc. Can be mentioned.

  Other specific examples of the compound having an aryl group partially substituted with a sulfonate group include ammonium salt, sodium salt and potassium salt of p-styrenesulfonic acid.

  Examples of the vinyl sulfonate compound having a vinyl group to which a group of ammonium salt, sodium salt or potassium salt of the sulfonic acid group is bonded include, for example, alkyl sulfonic acid (meth) acrylate such as 2-sulfoethyl acrylate and methylpropane sulfonic acid. Examples thereof include ammonium salts such as (meth) acrylamide and allylsulfonic acid, sodium salts, and potassium salts.

  Examples of the compound having a C2-C4 alkyl ether group or a C2-C4 polyalkyl ether group in which a part of the sulfate ester group is substituted with ammonium salt, sodium salt or potassium salt include Examples include compounds having an alkyl ether group partially substituted with a sulfonate group.

  Specific examples of the vinyl monomer having a nonionic group include α- (1-((allyloxy) methyl) -2- (nonylphenoxy) ethyl) -ω-hydroxypolyoxyethylene (trade name: ADEKA rear soap). NE-20, NE-30, NE-40, etc., manufactured by Asahi Denka Kogyo Co., Ltd.), polyoxyethylene alkylpropenyl phenyl ether (trade names: Aqualon RN-10, RN-20, RN-30, RN-50, etc.) , Manufactured by Daiichi Pharmaceutical Co., Ltd.).

  The amount of the emulsifier used is suitably within the range of 10% by mass or less, and preferably within the range of 0.001 to 5% by mass with respect to the polymer emulsion particles (A).

  In addition to the above emulsifiers, a dispersion stabilizer can also be used for the purpose of improving the water dispersion stability of the polymer emulsion particles (A). Examples of the dispersion stabilizer include various water-soluble oligomers selected from the group consisting of polycarboxylic acids and sulfonates, polyvinyl alcohol, hydroxyethyl cellulose, starch, maleated polybutadiene, maleated alkyd resin, polyacrylic acid (salt ), Various synthetic or natural water-soluble or water-dispersible water-soluble polymer materials such as polyacrylamide, water-soluble or water-dispersible acrylic resin, etc., and one or a mixture of two or more of these are used. be able to.

  When using these dispersion stabilizers, the amount used is suitably within the range of 10% by mass or less with respect to the polymer emulsion particles (A), and in particular, 0.001 to 5% by mass. Within the range is preferable.

  The polymerization of the hydrolyzable silicon compound (a2) and the vinyl monomer (a1) is preferably carried out in the presence of a polymerization catalyst.

  Examples of the polymerization catalyst for the hydrolyzable silicon compound (a2) include hydrogen halides such as hydrochloric acid and hydrofluoric acid, carboxylic acids such as acetic acid, trichloroacetic acid, trifluoroacetic acid and lactic acid, and sulfones such as sulfuric acid and p-toluenesulfonic acid. Acids, alkylbenzenesulfonic acid, alkylsulfonic acid, alkylsulfosuccinic acid, polyoxyethylene alkylsulfuric acid, polyoxyethylene alkylarylsulfuric acid, polyoxyethylene distyrylphenyl ether sulfonic acid and other acidic emulsifiers, acidic or weakly acidic inorganic salts, Acidic compounds such as phthalic acid, phosphoric acid, nitric acid; sodium hydroxide, potassium hydroxide, sodium methylate, sodium acetate, tetramethylammonium chloride, tetramethylammonium hydroxide, tributylamine, diazabicycloundecene, ethanol Basic compounds such as range amine, diethylenetriamine, ethanolamine, 3-aminopropyltrimethoxysilane, 3- (2-aminoethyl) -aminopropyltrimethoxysilane; tin such as dibutyltin octylate, dibutyltin dilaurate A compound etc. can be mentioned.

  On the other hand, the polymerization catalyst for the vinyl monomer (a1) is preferably a radical polymerization catalyst that undergoes radical decomposition by heat or a reducing substance to cause addition polymerization of the vinyl monomer, which is water-soluble or oil-soluble. Persulfates, peroxides, azobis compounds and the like are used. Examples include potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, t-butyl hydroperoxide, t-butyl peroxybenzoate, 2,2-azobisisobutyronitrile, 2,2-azobis. There are (2-diaminopropane) hydrochloride, 2,2-azobis (2,4-dimethylvaleronitrile), and the amount is preferably 0.001 to 5% by mass based on the total vinyl monomer. . When acceleration of polymerization and polymerization at a low temperature of 70 ° C. or lower are desired, it is advantageous to use a reducing agent such as sodium bisulfite, ferrous chloride, ascorbate, or longalite in combination with a radical polymerization catalyst. .

  The polymer emulsion particles (A) are composed of a vinyl monomer (a1) in the presence of water and an emulsifier (other vinyl monomers copolymerizable therewith may be used if necessary) and hydrolyzable silicon. The compound (a2) can be obtained by preferably polymerizing in the presence of a polymerization catalyst.

  Here, the polymerization of the vinyl monomer (a1) and the hydrolyzable silicon compound (a2) can be carried out separately, but if carried out at the same time, the organic / inorganic composite is formed on a micro scale by chemical bonds or the like. Can be achieved.

  The number average particle diameter of the polymer emulsion particles (A) is preferably 10 to 800 nm. More preferably, the water resistance and weather resistance of the coating film obtained with a particle size of 50 to 300 nm are significantly improved. The thickness of 10 nm or more is preferable from the viewpoint of improving practical physical properties such as water resistance. Moreover, it is preferable to set it as 800 nm or less from a viewpoint of superposition | polymerization stability.

  As a method for obtaining the polymer emulsion particles (A) having such a particle size, the vinyl monomer (a1) and the hydrolyzable silicon compound (a2) in the presence of a sufficient amount of water for the emulsifier to form micelles. So-called emulsion polymerization is the most suitable method.

  As a method of emulsion polymerization, for example, vinyl monomer (a1) (other vinyl monomers copolymerizable therewith may be used if necessary) and hydrolyzable silicon compound (a2), As it is or in an emulsified state, it is dropped into the reaction vessel all at once or in a batch, or continuously, and is about 30 to 150 ° C. in the presence of the polymerization catalyst, preferably from atmospheric pressure to 10 MPa as necessary. The polymerization may be performed at the reaction temperature. In some cases, the polymerization may be carried out at a pressure higher than this or at a temperature lower than this. The ratio of the total amount of hydrolyzable silicon compound and all vinyl monomers to water is preferably set so that the final solid content is in the range of 0.1 to 70% by mass, preferably 1 to 55% by mass. . Further, in order to grow or control the particle diameter in carrying out the emulsion polymerization, a seed polymerization method in which emulsion particles are preliminarily present in the aqueous phase may be employed. The polymerization reaction may be allowed to proceed in the range of pH in the system of preferably 1.0 to 10.0, more preferably 1.0 to 6.0. The pH can be adjusted using a pH buffer such as disodium phosphate, sodium hydrogen carbonate, ammonia.

  As a method for obtaining the polymer emulsion particles (A), the vinyl monomer (a1) and the hydrolyzable silicon compound (a2) in the presence of water and an emulsifier necessary for polymerizing the hydrolyzable silicon compound (a2). Can be applied after polymerization in the presence of a solvent, if necessary, until the polymerization product becomes an emulsion. This method is compared with the emulsion polymerization method described above. ) Is difficult to control.

  The polymer emulsion particles (A) preferably have a core / shell structure composed of two or more layers. According to the coating composition for undercoat (I) containing the polymer emulsion particles (A) having a core / shell structure, it is possible to form an undercoat layer having particularly excellent mechanical properties (balance of strength and flexibility, etc.). it can.

  Multi-stage emulsion polymerization is useful as a method for producing the polymer emulsion particles (A) having the core / shell structure. Multi-stage emulsion polymerization refers to the preparation of vinyl monomer (a1) (other vinyl monomers copolymerizable therewith) and hydrolyzable silicon compound (a2), if necessary, in separate stages. It means to polymerize separately.

  The undercoating coating composition (I) preferably contains an ultraviolet absorber and / or a light stabilizer in addition to the polymer emulsion particles (A). The ultraviolet absorber is at least one selected from the group consisting of benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, and triazine ultraviolet absorbers, and the light stabilizer is at least selected from the group consisting of hindered amine light stabilizers. One type can be used. The ultraviolet absorber and / or light stabilizer is preferably used in an amount of 0.1% by mass to 5% by mass with respect to the polymer emulsion particles (A). Also, use a radical polymerizable ultraviolet absorber having a radical polymerizable double bond in the molecule as the ultraviolet absorber, and a radical polymerizable light stabilizer having a radical polymerizable double bond in the molecule as the light stabilizer. You can also. In addition, it is preferable to use an ultraviolet absorber and a light stabilizer in combination because the resulting coating material has excellent weather resistance.

  These ultraviolet absorbers and light stabilizers can be simply blended with the polymer emulsion particles (A), or can be present together when synthesizing the polymer emulsion particles (A).

  Specific examples of the benzophenone ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, and 2-hydroxy-4-n. -Octoxybenzophenone, 2-hydroxy-4-n-dodecyloxybenzophenone, 2-hydroxy-4-benzyloxybenzophenone, bis (5-benzoyl-4-hydroxy-2-methoxyphenyl) methane, 2,2'-dihydroxy -4-methoxybenzophenone, 2,2'-dihydroxy-4,4'dimethoxybenzophenone, 2,2 ', 4,4'-tetrahydroxybenzophenone, 4-dodecyloxy-2-hydroxybenzophenone, 2-hydroxy-4- Methoxy-2'-carbo Shi benzophenone, and the like 2-hydroxy-4-stearyloxy benzophenone. Specific examples of the radical polymerizable benzophenone ultraviolet absorber include 2-hydroxy-4-acryloxybenzophenone, 2-hydroxy-4-methacryloxybenzophenone, 2-hydroxy-5-acryloxybenzophenone, 2-hydroxy-5- Methacryloxybenzophenone, 2-hydroxy-4- (acryloxyethoxy) benzophenone, 2-hydroxy-4- (methacryloxyethoxy) benzophenone, 2-hydroxy-4- (methacryloxydiethoxy) benzophenone, 2-hydroxy-4- (Acryloxytriethoxy) benzophenone.

  Specific examples of the benzotriazole ultraviolet absorber include 2- (2′-hydroxy-5′-methylphenyl) benzotriazole, 2- (2′-hydroxy-5′-tert-butylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-di-tert-butylphenyl) benzotriazole, 2- (2-hydroxy-5-tert-octylphenyl) benzotriazole, 2- (2-hydroxy-3,5- Di-tert-octylphenyl) benzotriazole, 2- (2′-hydroxy-3 ′, 5′-bis (α, α′-dimethylbenzyl) phenyl) benzotriazole), methyl-3- (3-tert-butyl) -5- (2H-benzotriazol-2-yl) -4-hydroxyphenyl) propionate and polyethylene Condensation product with glycol (molecular weight 300) (Nippon Ciba-Geigy Co., Ltd., trade name: TINUVIN 1130), isooctyl-3- (3- (2H-benzotriazol-2-yl) -5-tert-butyl-4-hydroxy Phenyl) propionate (Nippon Ciba-Geigy Co., Ltd., trade name: TINUVIN 384), 2- (3-dodecyl-5-methyl-2-hydroxyphenyl) benzotriazole (Nippon Ciba-Geigy Co., Ltd., trade name: TINUVIN 571), 2 -(2'-hydroxy-3'-tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2- (2'-hydroxy-3 ', 5'-di-tert-amylphenyl) benzotriazole , 2- (2′-Hydroxy-4′-octoxyphenyl) benzotria 2- (2′-hydroxy-3 ′-(3 ″, 4 ″, 5 ″, 6 ″ -tetrahydrophthalimidomethyl) -5′-methylphenyl) benzotriazole, 2,2-methylenebis (4- ( 1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2H-benzotriazol-2-yl) -4,6-bis (1-methyl) -1-phenylethyl) phenol (Nippon Ciba-Geigy Co., Ltd., trade name: TINUVIN900). Specifically, 2- (2′-hydroxy-5′-methacryloxyethylphenyl) -2H-benzotriazole (manufactured by Otsuka Chemical Co., Ltd., trade name: RUVA-93) as a radical polymerizable benzotriazole-based ultraviolet absorber. ), 2- (2′-hydroxy-5′-methacryloxyethyl-3-tert-butylphenyl) -2H-benzotriazole, 2- (2′-hydroxy-5′-methacryloxypropyl-3-tert-) Butylphenyl) -5-chloro-2H-benzotriazole, 3-methacryloyl-2-hydroxypropyl-3- (3 ′-(2 ″ -benzotriazolyl) -4-hydroxy-5-tert-butyl) phenylpropi Honate (Nippon Ciba-Geigy Co., Ltd., trade name: CGL-104).

  Specific examples of the triazine ultraviolet absorber include TINUVIN 384 and TINUVIN 400 (trade name, manufactured by Ciba Geigy Japan, Inc.).

  The undercoat coating composition (I) preferably contains a benzotriazole-based UV absorber or a triazine-based UV absorber having a high UV-absorbing ability as the UV absorber.

  Specific examples of the hindered amine light stabilizer include bis (2,2,6,6-tetramethyl-4-piperidyl) succinate, bis (2,2,6,6-tetramethylpiperidyl) sebacate, bis (1, 2,2,6,6-pentamethyl-4-piperidyl) 2- (3,5-di-tert-butyl-4-hydroxybenzyl) -2-butylmalonate, 1- (2- (3- (3 5-Di-tert-butyl-4-hydroxyphenyl) propynyloxy) ethyl) -4- (3- (3,5-di-tert-butyl-4-hydroxyphenyl) propynyloxy) -2,2,6 6-tetramethylpiperidine, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl-1,2,2,6,6-pentamethyl-4-piperidyl-sebake Mixture (manufactured by Nippon Ciba-Geigy Co., Ltd., trade name: TINUVIN 292), bis (1-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, TINUVIN 123 (trade name, Nippon Ciba-Geigy Co., Ltd.) Etc.). Specific examples of the radical polymerizable hindered amine light stabilizer include 1,2,2,6,6-pentamethyl-4-piperidyl methacrylate, 1,2,2,6,6-pentamethyl-4-piperidyl acrylate, 2, 2,6,6-tetramethyl-4-piperidyl methacrylate, 2,2,6,6-tetramethyl-4-piperidyl acrylate, 1,2,2,6,6-pentamethyl-4-iminopiperidyl methacrylate, 2, 2,6,6, -tetramethyl-4-iminopiperidyl methacrylate, 4-cyano-2,2,6,6-tetramethyl-4-piperidyl methacrylate, 4-cyano-1,2,2,6,6- Examples include pentamethyl-4-piperidyl methacrylate.

  As the hindered amine light stabilizer, those having low basicity are preferable, and specifically, those having a base constant (pKb) of 8 or more are preferable.

  The undercoat coating composition (I) is a component that is usually added to and blended with a paint, for example, a thickener, a leveling agent, a thixotropic agent, an antifoaming agent, a freezing stabilizer, depending on its use and usage method. Matting agent, cross-linking reaction catalyst, pigment, curing catalyst, cross-linking agent, filler, anti-skinning agent, dispersant, wetting agent, antioxidant, rheology control agent, antifoaming agent, film forming aid, rust preventive agent , Dyes, plasticizers, lubricants, reducing agents, preservatives, antifungal agents, deodorants, anti-yellowing agents, antistatic agents or charge control agents, etc. May be.

  The substrate 2 is not particularly limited. For example, an inorganic base material, an organic base material, an inorganic organic composite base material, and a coating base material having at least one inorganic coating film and / or at least one organic coating film on the surface of any of these materials can give. Examples of the inorganic coating film include silicone resin. The organic coating film is not particularly limited, and examples thereof include acrylic, alkyd, polyester, epoxy, urethane, and melamine.

  The method for applying the undercoating coating composition (I) onto the substrate 2 is not particularly limited. Examples thereof include spraying, flow coating, roll coating, brush coating, dip coating, spin coating, screen printing, casting, gravure printing, flexographic printing, and the like. Drying after application may be room temperature drying or heat drying.

  The top coating composition (II) includes a step of polymerizing the metal oxide particles (B) having photocatalytic activity, and a vinyl monomer and a hydrolyzable silicon compound simultaneously or separately in the presence of water and an emulsifier. It is an aqueous composition containing polymer emulsion particles (C) obtained by the method, colloidal silica (D), and water.

  The metal oxide particles (B) have a photocatalytic activity. Here, the photocatalyst refers to a substance that causes an oxidation or reduction reaction by light irradiation. That is, when light (excitation light) with an energy larger than the energy gap between the conduction band and the valence band (ie, a short wavelength) is irradiated, excitation (photoexcitation) of electrons in the valence band occurs, resulting in conduction. It is a substance that can generate electrons and holes. At this time, various chemical reactions are performed using the reducing power of electrons generated in the conduction band and / or the oxidizing power of holes generated in the valence band. Can do. The photocatalytic activity means that an oxidation or reduction reaction is caused by light irradiation. These photocatalytic activities can be determined, for example, by measuring the decomposability of organic substances such as pigments when the material surface is irradiated with light. A surface having photocatalytic activity exhibits excellent decomposition activity and contamination resistance of contaminating organic substances.

  The topcoat layer 12 containing the metal oxide particles (B) having photocatalytic activity exhibits hydrophilicity. The hydrophilicity preferably refers to a case where the contact angle of water at 20 ° C. is 60 degrees or less, and the surface having hydrophilicity with a contact angle of water of 35 degrees or less is particularly capable of self-purification by water such as rainfall. It is preferable because it exhibits stain resistance due to (self-cleaning). Further, from the viewpoint of excellent stain resistance and antifogging properties, the contact angle of water on the surface is preferably 20 degrees or less, and more preferably 10 degrees or less.

  Examples of the metal oxide constituting the metal oxide particles (B) having photocatalytic activity include a semiconductor compound having a band gap energy of preferably 1.2 to 5.0 eV, more preferably 1.5 to 4.1 eV. Can do. When the band gap energy is smaller than 1.2 eV, the ability to cause oxidation and reduction reaction by light irradiation becomes weak. When the band gap energy is larger than 5.0 eV, the energy of light necessary for generating holes and electrons becomes very large.

Examples of the metal oxide include TiO ₂ , ZnO, SrTiO ₃ , BaTiO ₃ , BaTiO ₄ , BaTi ₄ O ₉ , K ₂ NbO ₃ , Nb ₂ O ₅ , Fe ₂ O ₃ , Ta ₂ O ₅ , K ₃ Ta. ₃ Si ₂ O ₃ , WO ₃ , SnO ₂ , Bi ₂ O ₃ , BiVO ₄ , NiO, Cu ₂ O, RuO ₂ and CeO ₂ are selected. As a metal oxide, a layered oxide having at least one element selected from Ti, Nb, Ta, and V (for example, JP-A-62-274452, JP-A-2-172535, JP-A-7-24329) JP-A-8-89799, JP-A-8-89800, JP-A-8-89804, JP-A-8-198061, JP-A-9-248465, JP-A-10-99694, JP-A-10-244165 can also be used.

Among these metal oxides, TiO ₂ (titanium oxide) is preferable because it is harmless and has excellent chemical stability. As the titanium oxide, any crystal system of anatase, rutile and brookite can be used.

  The metal oxide particles (B) may be added or fixed with a metal such as Pt, Rh, Ru, Nb, Cu, Sn, Ni, Fe, and / or an oxide thereof, and may be silica or porous. It may be coated with calcium phosphate or the like (see, for example, JP-A-10-244166).

  Regarding the shape of the metal oxide particles (B) having photocatalytic activity, the ratio (l / d) of the particle length (l) to the particle diameter (d) is 1/1 from the viewpoint of the specific surface area and the particle orientation effect. It is preferably in the range of 20/1. More preferably, (l / d) is in the range of 1/1 to 15/1.

  When a conductive metal oxide is selected as the metal oxide constituting the metal oxide particles (B) having photocatalytic activity, the composite coating film 1 exhibits conductive performance, antistatic performance, electromagnetic wave shielding performance, and surface heat generation performance. Therefore, it is preferable.

  Examples of the metal oxide having conductivity that can be usefully used include tin-doped indium oxide (ITO), antimony-doped tin oxide (ATO), tin oxide, and zinc oxide.

  In order to form a coating film excellent in transparency, strength, weather resistance, etc., the particle diameter of the metal oxide particles (B) having photocatalytic activity is preferably 1 to 400 nm, more preferably 1 to 100 nm, and still more preferably. 5-50 nm.

  The metal oxide particles (B) can be added to the coating composition in any form of powder, dispersion and sol. The sol of the metal oxide particles (B) and the dispersion of the metal oxide particles (B) are 0.01 to 80% by mass of photocatalyst particles (metal oxide particles) in water and / or a hydrophilic organic solvent. It is preferably 0.1 to 50% by mass and dispersed as primary particles and / or secondary particles.

  Examples of the hydrophilic organic solvent used in the sol or dispersion of the metal oxide particles (B) include alcohols such as ethylene glycol, butyl cellosolve, n-propanol, isopropanol, n-butanol, ethanol and methanol, acetone and methyl ethyl ketone. , Ketones such as methyl isobutyl ketone, ethers such as tetrahydrofuran and dioxane, amides such as dimethylacetamide and dimethylformamide, dimethyl sulfoxide, nitrobenzene, and a mixture of two or more of these.

  The polymer emulsion particles (C) used in the top coating composition (II) include a step of polymerizing the hydrolyzable silicon compound (c1) and the vinyl monomer (c2) in the presence of water and an emulsifier, respectively. It can be obtained by a method.

  At this time, the mass ratio (c1) / (c2) of the vinyl monomer (c2) to the hydrolyzable silicon compound (c1) is 5/95 to 95/5, preferably 10/90 to 90/10. .

  The polymer emulsion particles (C) thus obtained are a composite of the polymerization product of the hydrolyzable silicon compound (c1) and the polymerization product of the vinyl monomer (c2).

The hydrolyzable silicon compound (c1) used for producing the polymer emulsion particles (C) is represented by the following formula (1), which is the same as that for producing the polymer emulsion particles (A). And the condensation products thereof, and silane coupling agents.
SiWxRy (1)
(In the formula, W represents an alkoxy group having 1 to 20 carbon atoms, a hydroxyl group, an acetoxy group having 1 to 20 carbon atoms, a halogen atom, a hydrogen atom, an oxime group having 1 to 20 carbon atoms, an enoxy group, an aminoxy group, and an amide group. Represents at least one selected group, and R represents a linear or branched alkyl group having 1 to 30 carbon atoms, a cycloalkyl group having 5 to 20 carbon atoms, and an alkyl having 1 to 20 carbon atoms. Represents at least one hydrocarbon group selected from a group, an alkoxy group having 1 to 20 carbon atoms, or an aryl group having 6 to 20 carbon atoms which may be substituted with a halogen atom, x is an integer of 1 or more and 4 or less. Y is an integer of 0 or more and 3 or less, and x + y = 4.) As W, a silicon alkoxide having at least one alkoxy group is preferable.

  Here, the silane coupling agent represents a hydrolyzable silicon compound in which a functional group having reactivity with an organic substance such as a vinyl group, an epoxy group, an amino group, a methacryl group, a mercapto group, or an isocyanate group exists in the molecule.

  When the silicon alkoxide or silane coupling agent is used as a condensation product, the condensation product preferably has a polystyrene equivalent weight average molecular weight of 200 to 5,000, more preferably 300 to 1,000.

  Dimethyldimethoxysilane, dimethyldiethoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, di-n-propyldimethoxysilane, di-n-propyldiethoxysilane, diisopropyldimethoxysilane, diisopropyldiethoxysilane, di-n-butyldimethoxy Silane, di-n-butyldiethoxysilane, di-n-pentyldimethoxysilane, di-n-pentyldiethoxysilane, di-n-hexyldimethoxysilane, di-n-hexyldiethoxysilane, di-n-heptyl Dimethoxysilane, di-n-heptyldiethoxysilane, di-n-octyldimethoxysilane, di-n-octyldiethoxysilane, di-n-cyclohexyldimethoxysilane, di-n-cyclohexyldiethoxysilane, diphenyldimethyl Kishishiran, it is preferable in terms of issuing the flexibility of the coating film combination dialkoxy silanes such as diphenyl diethoxy silane and other alkoxysilanes.

  Among the silicon alkoxides, silicon alkoxides having a phenyl group, for example, phenyltrimethoxysilane, phenyltriethoxysilane, diphenyldimethoxysilane, and the like are very preferable because of excellent polymerization stability in the presence of water and an emulsifier.

  The hydrolyzable silicon compound (c2) may contain a silane coupling agent having a vinyl group or a thiol group. It is possible to generate a chemical bond by copolymerization or a chain transfer reaction of a silane coupling agent having a vinyl group or a thiol group and a vinyl monomer (c1). When the silane coupling agent having a vinyl group or a thiol group is used alone or mixed or complexed with the above-mentioned silicon alkoxide, silane coupling agent, and their condensation products, polymer emulsion particles (C) The polymerization product of the hydrolyzable silicon compound (c2) and the polymerization product of the vinyl monomer (a1) constituting can be combined by a covalent bond in addition to a hydrogen bond. Compounding makes it excellent in weather resistance.

  Examples of the silane coupling agent having a vinyl group include 3- (meth) acryloxypropyltrimethoxysilane, 3- (meth) acryloxypropyltriethoxysilane, 3- (meth) acryloxypropylmethyldimethoxysilane, 3- Group consisting of (meth) acryloxypropyltri-n-propoxysilane, 3- (meth) acryloxypropyltriisopropoxysilane, vinyltrimethoxysilane, vinyltriethoxysilane, allyltrimethoxysilane and 2-trimethoxysilylethyl vinyl ether More selected. The silane coupling agent having a thiol group is selected from, for example, 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane.

  Examples of the vinyl monomer (c2) used to produce the polymer emulsion particles (C) include acrylic acid esters, methacrylic acid esters, aromatic vinyl compounds, vinyl cyanides, and carboxyl group-containing vinyl monomers. Monomers containing functional groups such as hydroxyl group-containing vinyl monomers, epoxy group-containing vinyl monomers, carbonyl group-containing vinyl monomers, anionic vinyl monomers, amide group-containing vinyl monomers, etc. Can be mentioned.

  Examples of the (meth) acrylic acid ester include (meth) acrylic acid alkyl ester having 1 to 50 carbon atoms in the alkyl portion, and (poly) oxyethylene di (meth) acrylate having 1 to 100 ethylene oxide groups. Etc. Specific examples of (meth) acrylic acid esters include methyl (meth) acrylate, ethyl (meth) acrylate, n-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and methyl (meth) acrylate. Examples include cyclohexyl, cyclohexyl (meth) acrylate, lauryl (meth) acrylate, dodecyl (meth) acrylate, and the like. Specific examples of (poly) oxyethylene di (meth) acrylate include ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, diethylene glycol methoxy (meth) acrylate, tetraethylene glycol di (meth) acrylate Etc.

  In the present specification, (meth) acryl is a simple description of methacryl or acryl. The amount of (meth) acrylic acid ester used is preferably 0 to 99.9% by mass, more preferably 5 to 80% by mass, based on the entire vinyl monomer (c2), as one or a mixture of two or more. is there.

  Examples of the carboxyl group-containing vinyl monomer include acrylic acid, methacrylic acid, crotonic acid, itaconic acid, maleic acid, fumaric acid and maleic anhydride, and half of dibasic acids such as itaconic acid, maleic acid and fumaric acid. There is an ester. By using a carboxylic acid group-containing vinyl monomer, a carboxyl group can be introduced into the polymer emulsion particles (C), improving the stability as an emulsion, and having a resistance to dispersion and destruction from the outside. It is possible to have it. At this time, a part or all of the introduced carboxyl group can be neutralized with an amine such as ammonia, triethylamine or dimethylethanolamine, or a base such as sodium hydroxide or potassium hydroxide.

  It is preferable from the surface of water resistance that the usage-amount of a carboxyl group-containing vinyl monomer is 0-30 mass% with respect to the whole vinyl monomer (c2) as a 1 type, or 2 or more types of mixture. More preferably, it is 0.1-10 mass%.

  Examples of the hydroxyl group-containing vinyl monomer include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 3-hydroxybutyl. Hydroxyalkyl esters of (meth) acrylic acid such as (meth) acrylate and 4-hydroxybutyl (meth) acrylate, di-2-hydroxyethyl fumarate, mono-2-hydroxyethyl monobutyl fumarate, allyl alcohol and ethylene oxide (Poly) oxyethylene mono (meth) acrylate having 1 to 100 groups, (poly) oxypropylene mono (meth) acrylate having 1 to 100 propylene oxide groups, and “Placcel FM, FA” monomer" Daicel Chemical Industries of Ltd., trade name of caprolactone addition monomer) and other alpha, and the like hydroxyalkyl esters of β- ethylenically unsaturated carboxylic acid. Specific examples of the (poly) oxyethylene (meth) acrylate include ethylene glycol (meth) acrylate, ethylene glycol methoxy (meth) acrylate, diethylene glycol (meth) acrylate, diethylene glycol methoxy (meth) acrylate, (meth ) Tetraethylene glycol acrylate, tetraethylene glycol methoxy (meth) acrylate, and the like. Specific examples of (poly) oxypropylene (meth) acrylate include propylene glycol (meth) acrylate, propylene glycol methoxy (meth) acrylate, dipropylene glycol (meth) acrylate, dimethoxy meth (meth) acrylate. Examples include propylene glycol, tetrapropylene glycol (meth) acrylate, and tetrapropylene glycol methoxy (meth) acrylate. By using a hydroxyl group-containing vinyl monomer, it is possible to improve the water dispersion stability of the polymer emulsion particles (C).

  The amount of the hydroxyl group-containing vinyl monomer described above is preferably 0.1 to 50% by mass, more preferably 0.1%, based on the entire vinyl monomer (c2), as one or a mixture of two or more. -10 mass%.

  Examples of the glycidyl group-containing vinyl monomer include glycidyl (meth) acrylate, allyl glycidyl ether, and allyl dimethyl glycidyl ether. When a glycidyl group-containing vinyl monomer or a carbonyl group-containing vinyl monomer is used, the polymer emulsion particles (A) are reactive and crosslinked with hydrazine derivatives, carboxylic acid derivatives, isocyanate derivatives, etc. It is possible to form a coating film having excellent properties. The amount of the glycidyl group-containing vinyl monomer or the carbonyl group-containing vinyl monomer used is preferably 0 to 50% by mass with respect to the entire vinyl monomer (c2).

  Specific examples of vinyl monomers other than the above include olefins such as (meth) acrylamide, ethylene, propylene, isobutylene, dienes such as butadiene, vinyl chloride, vinylidene chloride, vinyl fluoride, tetrafluoroethylene, chloro Haloolefins such as trifluoroethylene, vinyl acetate, vinyl propionate, vinyl n-butyrate, vinyl benzoate, vinyl pt-butylbenzoate, vinyl pivalate, vinyl 2-ethylhexanoate, vinyl versatate, laurin Carboxylic acid vinyl esters such as vinyl acid, isopropenyl acetate, isopropenyl carboxylic acid such as isopropenyl acetate, vinyl ethers such as ethyl vinyl ether, isobutyl vinyl ether, cyclohexyl vinyl ether, styrene, vinyl Aromatic vinyl compounds such as toluene, allyl esters such as allyl acetate and allyl benzoate, allyl ethers such as allyl ethyl ether and allyl phenyl ether, and 4- (meth) acryloxy-2,2,6,6,- Tetramethylpiperidine, 4- (meth) acryloxy-1,2,2,6,6, -pentamethylpiperidine, perfluoromethyl (meth) acrylate, perfluoropropyl (meth) acrylate, perfluoropropylmethyl (meth) Examples thereof include acrylate, vinylpyrrolidone, trimethylolpropane tri (meth) acrylate, allyl (meth) acrylate, and the like, and combinations thereof.

  The vinyl monomer (c2) preferably contains an amide group-containing vinyl monomer having a secondary amide group and / or a tertiary amide group. Examples of the amide group-containing vinyl monomer include N-alkyl or N-alkylene-substituted (meth) acrylamide. Specifically, for example, N-methylacrylamide, N-methylmethacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, N, N-dimethylmethacrylamide, N, N-diethylacrylamide, N-ethylmethacrylamide, N-methyl-N-ethylacrylamide, N-methyl-N-ethylmethacrylamide, N-isopropylacrylamide, Nn-propylacrylamide, N-isopropylmethacrylamide, Nn-propylmethacrylamide, N-methyl-N -N-propylacrylamide, N-methyl-N-isopropylacrylamide, N-acryloylpyrrolidine, N-methacryloylpyrrolidine, N-acryloylpiperidine, N-methacryloylpiperidine, N-acryloylhexahydroazepine, N-acrylo Ilmorpholine, N-methacryloylmorpholine, N-vinylpyrrolidone, N-vinylcaprolactam, N, N'-methylenebisacrylamide, N, N'-methylenebismethacrylamide, N-vinylacetamide, diacetone acrylamide, diacetone acrylamide , N-methylol acrylamide, and N-methylol methacrylamide.

  In particular, use of a vinyl monomer having a tertiary amide group is preferable because the hydrogen bondability with the hydroxyl group of the polymerization product of the hydrolyzable silicon compound (c1) is increased. Among the above amide group-containing vinyl monomers, N, N-diethylacrylamide is particularly excellent in polymerization stability in the presence of water and an emulsifier, and the above-mentioned hydrolyzable silicon compound (c1) is produced by polymerization. It is very preferable because it can form a strong hydrogen bond with the hydroxyl group of the product and the hydroxyl group of the metal oxide (B) having photocatalytic activity.

  The amount of the amide group-containing vinyl monomer used is 10/90 to 70/30 as a mass ratio (amide group-containing vinyl monomer / polymer emulsion particle (C)) to the resulting polymer emulsion particle (C). It is preferable that The mass ratio of the amide group-containing vinyl monomer to the metal oxide particles (B) having photocatalytic activity described above is preferably 1/10 to 10/1. When the amide group-containing vinyl monomer is present in this range, the hydrogen bonding force and the compounding stability of the metal oxide particles (B) are preferably compatible.

  In the synthesis of the polymer emulsion particles (C), a chain transfer agent may be used for the purpose of controlling the molecular weight of the polymer.

  Examples of such chain transfer agents include alkyl mercaptans such as n-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan; aromatic mercaptans such as benzyl mercaptan and dodecyl benzyl mercaptan; thiocarboxylic acids such as thiomalic acid. Examples include acids or their salts or alkyl esters thereof, or polythiols, diisopropylxanthogen disulfide, di (methylenetrimethylolpropane) xanthogen disulfide and thioglycol, and allyl compounds such as dimers of α-methylstyrene. it can.

  Examples of the emulsifier that can be used for the synthesis of the polymer emulsion particles (C) include alkylbenzenesulfonic acid, alkylsulfonic acid, alkylsulfosuccinic acid, polyoxyethylene alkylsulfuric acid, polyoxyethylene alkylarylsulfuric acid, polyoxyethylene distyryl. Acidic emulsifiers such as phenyl ether sulfonic acid, alkali metal (Li, Na, K etc.) salts of acidic emulsifiers, anionic surfactants such as ammonium salts of acidic emulsifiers, fatty acid soaps, and alkyltrimethylammonium bromides, alkylpyridinium bromides , Quaternary ammonium salts such as imidazolinium laurate, pyridinium salts, imidazolinium salt type cationic surfactants, polyoxyethylene alkyl aryl ethers, polyoxyethylene sorbitan fats Esters, polyoxyethylene Oki polyoxyethylene polyoxypropylene block copolymers can be exemplified reactive emulsifier or the like having a double bond of nonionic surface active agent and a radical polymerizable polyoxyethylene distyryl phenyl ether.

  Among these emulsifiers, when a reactive emulsifier having a radical polymerizable double bond is selected, the water dispersion stability of the polymer emulsion particles (C) becomes very good, and the polymer emulsion particles (C The topcoat layer 12 formed using a coating composition containing) is preferable because it is excellent in water resistance, chemical resistance, strength, and the like.

  Examples of the reactive emulsifier having a radical polymerizable double bond include a vinyl monomer having a sulfonic acid group or a sulfonate group, a vinyl monomer having a sulfate ester group, an alkali metal salt thereof, an ammonium salt, Examples include vinyl monomers having a nonionic group such as oxyethylene, and vinyl monomers having a quaternary ammonium salt.

  As a specific example of the reactive emulsifier, taking a vinyl monomer salt having a sulfonic acid group or a sulfonate group as an example, it has a radical polymerizable double bond, and a part of the sulfonic acid group is an ammonium salt. An alkyl group having 1 to 20 carbon atoms, an alkyl ether group having 2 to 4 carbon atoms, a polyalkyl ether group having 2 to 4 carbon atoms, an aryl group having 6 or 10 carbon atoms, substituted with a sodium salt or a potassium salt, and It is a compound having a substituent selected from the group consisting of a succinic acid group, or a vinyl sulfonate compound having a vinyl group to which a group which is an ammonium salt, sodium salt or potassium salt of a sulfonic acid group is bonded. The vinyl monomer having a sulfate ester group is an alkyl having 1 to 20 carbon atoms, which has a radical polymerizable double bond and a part of the sulfate ester group is substituted with an ammonium salt, a sodium salt or a potassium salt. A compound having a substituent selected from the group consisting of a group, an alkyl ether group having 2 to 4 carbon atoms, a polyalkyl ether group having 2 to 4 carbon atoms, and an aryl group having 6 or 10 carbon atoms.

  Specific examples of the compound having a succinic acid group in which a part of the sulfonic acid group is substituted with an ammonium salt, a sodium salt or a potassium salt include allylsulfosuccinate. Specific examples thereof include, for example, Eleminol JS-2 (trade name) (manufactured by Sanyo Kasei Co., Ltd.), Latemuru S-120, S-180A or S-180 (trade name) (manufactured by Kao Corporation), and the like. Can be mentioned.

  Further, as specific examples of the compound having a C2-C4 alkyl ether group or a C2-C4 polyalkyl ether group partially substituted with the ammonium salt, sodium salt or potassium salt of the sulfonic acid group, For example, Aqualon HS-10 or KH-1025 (trade name) (Daiichi Kogyo Seiyaku Co., Ltd.), Adekaria soap SE-1025N or SR-1025 (trade name) (Asahi Denka Kogyo Co., Ltd.), etc. Can be mentioned.

  Other specific examples of the compound having an aryl group partially substituted with a sulfonate group include ammonium salt, sodium salt and potassium salt of p-styrenesulfonic acid.

  Examples of the vinyl sulfonate compound having a vinyl group to which a group of ammonium salt, sodium salt or potassium salt of the sulfonic acid group is bonded include, for example, alkyl sulfonic acid (meth) acrylate such as 2-sulfoethyl acrylate, and methylpropane sulfonic acid. Examples thereof include ammonium salts such as (meth) acrylamide and allyl sulfonic acid, sodium salts, and potassium salts.

  Examples of the compound having a C2-C4 alkyl ether group or a C2-C4 polyalkyl ether group in which a part of the sulfate ester group is substituted with ammonium salt, sodium salt or potassium salt include Examples include compounds having an alkyl ether group partially substituted with a sulfonate group.

  Specific examples of the vinyl monomer having a nonionic group include α- (1-((allyloxy) methyl) -2- (nonylphenoxy) ethyl) -ω-hydroxypolyoxyethylene (trade name: ADEKA rear soap). NE-20, NE-30, NE-40, etc., manufactured by Asahi Denka Kogyo Co., Ltd.), polyoxyethylene alkylpropenyl phenyl ether (trade names: Aqualon RN-10, RN-20, RN-30, RN-50, etc.) , Manufactured by Daiichi Pharmaceutical Co., Ltd.).

  As the usage-amount of the said emulsifier, the inside which is 10 mass% or less with respect to polymer emulsion particle | grains (C) is suitable, and the inside which is 0.001-5 mass% is especially preferable.

  In addition to the above-mentioned emulsifier, a dispersion stabilizer can be used for the purpose of improving the water dispersion stability of the polymer emulsion particles (C). Examples of the dispersion stabilizer include various water-soluble oligomers selected from the group consisting of polycarboxylic acids and sulfonates, polyvinyl alcohol, hydroxyethyl cellulose, starch, maleated polybutadiene, maleated alkyd resin, polyacrylic acid (salt ), Various synthetic or natural water-soluble or water-dispersible water-soluble polymer materials such as polyacrylamide, water-soluble or water-dispersible acrylic resin, etc., and one or a mixture of two or more of these are used. be able to.

  When these dispersion stabilizers are used, the amount used is suitably within 10% by mass or less with respect to the polymer emulsion particles (C), and in particular, 0.001 to 5% by mass. Within the range is preferable.

  The polymerization of the hydrolyzable silicon compound (c1) and the vinyl monomer (c2) is preferably carried out in the presence of a polymerization catalyst.

  Here, as a polymerization catalyst for the hydrolyzable silicon compound (c1), hydrogen halides such as hydrochloric acid and hydrofluoric acid, carboxylic acids such as acetic acid, trichloroacetic acid, trifluoroacetic acid and lactic acid, sulfuric acid, and p-toluenesulfonic acid Sulfonic acids such as alkylbenzene sulfonic acid, alkyl sulfonic acid, alkyl sulfosuccinic acid, polyoxyethylene alkyl sulfuric acid, polyoxyethylene alkyl aryl sulfuric acid, polyoxyethylene distyryl phenyl ether sulfonic acid, etc., acidic or weakly acidic emulsifier Acidic compounds such as inorganic salts, phthalic acid, phosphoric acid, nitric acid; sodium hydroxide, potassium hydroxide, sodium methylate, sodium acetate, tetramethylammonium chloride, tetramethylammonium hydroxide, tributylamine, diazabicyclounde Basic compounds such as ethylene, ethylenediamine, diethylenetriamine, ethanolamines, γ-aminopropyltrimethoxysilane, γ- (2-aminoethyl) -aminopropyltrimethoxysilane; such as dibutyltin octylate, dibutyltin dilaurate A tin compound etc. can be mentioned.

  On the other hand, as the polymerization catalyst for the vinyl monomer (c2), a radical polymerization catalyst that undergoes radical decomposition by heat or a reducing substance to cause addition polymerization of the vinyl monomer is preferable, and is water-soluble or oil-soluble. Persulfates, peroxides, azobis compounds and the like are used. Examples include potassium persulfate, sodium persulfate, ammonium persulfate, hydrogen peroxide, t-butyl hydroperoxide, t-butyl peroxybenzoate, 2,2-azobisisobutyronitrile, 2,2-azobis. There are (2-diaminopropane) hydrochloride, 2,2-azobis (2,4-dimethylvaleronitrile), and the amount is preferably 0.001 to 5% by mass based on the total vinyl monomer. . When acceleration of polymerization and polymerization at a low temperature of 70 ° C. or lower are desired, it is advantageous to use a reducing agent such as sodium bisulfite, ferrous chloride, ascorbate, or longalite in combination with a radical polymerization catalyst. .

  As described above, the polymer emulsion particles (C) used in the top coating composition (II) are prepared by mixing the hydrolyzable silicon compound (c1) and the vinyl monomer (c2) (necessary) in the presence of water and an emulsifier. If appropriate, other vinyl monomers copolymerizable therewith may be used by polymerization in the presence of a polymerization catalyst.

  Here, the polymerization of the hydrolyzable silicon compound (c1) and the vinyl monomer (c2) can be carried out separately, but by carrying out at the same time, a micro organic / inorganic composite by chemical bonding or the like is performed. Can be achieved.

  In the present embodiment, it is important that the particle diameter of the polymer emulsion particles (C) is 10 to 800 nm. More preferably, the water resistance and weather resistance of the coating film obtained when the particle diameter is 50 to 300 nm are improved. In the production of particles of 10 nm or less by emulsion polymerization, too much emulsifier is used, resulting in poor practical properties such as water resistance. Further, particles having a diameter of 800 nm or more are difficult to produce because of poor polymerization stability.

  As a method for obtaining polymer emulsion particles (C) having such a particle size, hydrolyzable silicon compound (c1) and vinyl monomer (c2) in the presence of a sufficient amount of water for the emulsifier to form micelles. So-called emulsion polymerization is the most suitable method.

  As a method of emulsion polymerization, for example, the hydrolyzable silicon compound (c1) and the vinyl monomer (c2) (other vinyl monomers copolymerizable therewith may be used if necessary) As it is or in an emulsified state, it is dropped into the reaction vessel all at once or in a batch or continuously, and is about 30 to 150 ° C. in the presence of the polymerization catalyst, preferably from atmospheric pressure to 10 MPa as necessary. The polymerization may be performed at the reaction temperature. In some cases, the polymerization may be carried out at a pressure higher than this or at a temperature lower than this. The ratio of the hydrolyzable silicon compound (c1), the total amount of all vinyl monomers, and water is set so that the final solid content is in the range of 0.1 to 70% by mass, preferably 1 to 55% by mass. Is preferred. Further, in order to grow or control the particle diameter in carrying out the emulsion polymerization, a seed polymerization method in which emulsion particles are preliminarily present in the aqueous phase may be employed. The polymerization reaction may be allowed to proceed in the range of the pH in the system preferably from 1.0 to 10.0, more preferably from 1.0 to 6.0. The pH can be adjusted by using a pH buffer such as disodium phosphate, sodium hydrogen carbonate, or ammonia.

  As a method for obtaining the polymer emulsion particles (C), the hydrolyzable silicon compound (c1) and the vinyl monomer (c2) in the presence of water and an emulsifier necessary for polymerizing the hydrolyzable silicon compound (c1). ) Is polymerized in the presence of a solvent, if necessary, and a method of adding water until the polymerization product becomes an emulsion can also be applied. Compared with the emulsion polymerization method described above, the resulting polymer emulsion particles (C) particles Diameter control is difficult.

  When the polymer emulsion particles (C) have a core / shell structure formed of two or more layers, the mechanical properties (balance of strength and flexibility, etc.) are obtained from the coating composition (II) for top coating. It is possible to form a coating film excellent in the above). In particular, the mass ratio (c2) / (c1) of the vinyl monomer (c2) to the hydrolyzable silicon compound (c1) in the innermost layer is 1.0 or less, and the mass ratio (c2) of the outermost layer. When / (c1) is 0.1 or more and 5.0 or less, the resulting coating film is preferable because both weather resistance and mechanical properties are good.

  As a method for producing the polymer emulsion particles (C) having the core / shell structure, multistage emulsion polymerization is very useful.

  Here, multistage emulsion polymerization means two or more different hydrolyzable silicon compounds (c1) and vinyl monomers (c2) (other vinyl monomers copolymerizable therewith if necessary) ) And polymerizing them in separate stages.

  The synthesis of polymer emulsion particles (C) by multi-stage emulsion polymerization will be described below by taking as an example the synthesis of polymer emulsion particles (C) by 2-stage emulsion polymerization, which is the simplest and most useful among multi-stage emulsion polymerizations.

  Seed particles obtained by polymerizing vinyl monomer (c2) and / or hydrolyzable silicon compound (c1) in the presence of water and an emulsifier, for example, as a synthesis of polymer emulsion particles (C) by two-stage emulsion polymerization A method of polymerizing the hydrolyzable silicon compound (c1) and / or the vinyl monomer (c2) in the presence of the compound can be exemplified.

  The synthesis of the polymer emulsion particles (C) by the two-stage emulsion polymerization includes the first stage polymerization in which the hydrolyzable silicon compound (c1) and / or the vinyl monomer (c2) is supplied and emulsion polymerization is performed. Subsequent to the stage, a hydrolyzable silicon compound (c1) and / or a vinyl monomer (c2) is supplied, and this is carried out by a two-stage polymerization process comprising a second stage polymerization in which emulsion polymerization is carried out in an aqueous medium. At this time, the mass ratio of the solid content mass (M1) of the first stage reaction and the solid content mass (M2) of the second stage reaction is preferably (M1) / (M2) = 9/1 to 1/9. Preferably, it is 8/2 to 2/8.

  A preferred core / shell structure polymer is characterized in that the particle size of the seed particles obtained by the first stage polymerization is not greatly changed in the particle size distribution (volume average particle size / number average particle size) (preferably (In a monodispersed state), it can be increased by the second stage polymerization (increase in particle diameter).

  The core / shell structure can be confirmed by, for example, morphological observation with a transmission electron microscope, analysis by viscoelasticity measurement, or the like.

  In the presence of seed particles (core) obtained by polymerizing the polymer emulsion particles (C) with the hydrolyzable silicon compound (c1) in the presence of water and an emulsifier, the hydrolyzable silicon compound (c1) and the vinyl simple substance. When the shell is formed by polymerizing the monomer (c2), the polymerization stability is excellent, which is preferable.

  Further, in the above-described polymer emulsion particles (C) having a core / shell structure, when the glass transition temperature (Tg) of the core phase is 0 ° C. or lower, that is, the glass transition temperature of the seed particles is 0 ° C. or lower, The coating material to be contained is preferable because it is excellent in flexibility at room temperature and can form a coating film that is not easily cracked.

  When carrying out multi-stage emulsion polymerization of three or more stages, the number of stages to be polymerized should be increased with reference to the synthesis example of the polymer emulsion particles (C) by the two-stage polymerization described above

  The top coating composition (II) is prepared using water-dispersed colloidal silica (D). By containing colloidal silica, hydrophilicity is exhibited even without light irradiation. Moreover, the coating film which consists of coating composition (II) containing colloidal silica has the outstanding weather resistance.

  Colloidal silica can be prepared by a sol-gel method, or a commercially available product can be used. In the case of adjusting by the sol-gel method, refer to Color Material Association Journal, 61 (9) 488-493 (1988). The number average particle size of the colloidal silica is preferably 1 to 400 nm, more preferably 1 to 100 nm, still more preferably 5 to 50 nm, and most preferably 8 to 20 nm. When the particle size is 1 nm or less, the storage stability of the coating composition is not good. In the case of 400 nm or more, the transparency of the coating film is not good.

  Colloidal silica can be used regardless of whether it is acidic or basic in a water-dispersed state.

  Examples of acidic colloidal silica include commercially available products from Nissan Chemical Industries, Snowtex (trademark), Snowtex (trademark) -O, Snowtex-OS, and Asahi Denka Kogyo Co., Ltd., Adelite (trademark) AT-. 20Q, Clariant Japan Clevozole (trademark) 20H12, Clevozole 30CAL25, etc. can be used.

  Examples of basic colloidal silica include silica stabilized by the addition of alkali metal ions, ammonium ions, and amines. For example, SNOWTEX-20, SNOWTEX-30, SNOWTEX-C30, SNOWTEX-CM40, SNOWTEX-N, SNOWTEX-N30, SNOWTEX-K, Snow, manufactured by Nissan Chemical Industries, Ltd. Tex-XL, Snowtex-YL, Snowtex-ZL, Snowtex-PS-M, Snowtex-PS-L, etc., Adelite AT-20, Adelite AT-30, Adelite AT-20N manufactured by Asahi Denka Kogyo Co., Ltd. , Adelite AT-30N, Adelite AT-20A, Adelite AT-30A, Adelite AT-40, Adelite AT-50, Clevosol 30R9, Clevozol 30R50, Clevozol 50R50, etc. manufactured by Clariant Japan.

  These colloidal silicas may be used alone or in combination. Alumina, sodium aluminate or the like may be included as a minor component. Colloidal silica may also contain an inorganic base (sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonia) or an organic base (tetramethylammonium) as a stabilizer.

  The coating composition for topcoat (II) is usually added to the paint depending on its application and method of use, for example, thickener, leveling agent, thixotropic agent, antifoaming agent, freeze stability Agents, matting agents, crosslinking reaction catalysts, pigments, curing catalysts, crosslinking agents, fillers, anti-skinning agents, dispersants, wetting agents, antioxidants, rheology control agents, antifoaming agents, film-forming aids, prevention Select and combine rusting agents, dyes, plasticizers, lubricants, reducing agents, preservatives, antifungal agents, deodorants, anti-yellowing agents, antistatic agents, or charge control agents, etc., according to their respective purposes. Can be blended. Moreover, an ultraviolet absorber and a light stabilizer can be included like the coating composition (I) for undercoat. The ultraviolet absorber is at least one selected from the group consisting of benzophenone ultraviolet absorbers, benzotriazole ultraviolet absorbers, and triazine ultraviolet absorbers, and at least one selected from the group consisting of hindered amine light stabilizers as light stabilizers. Seeds can be used.

  The topcoat coating composition (II) is applied on the undercoat layer 11 formed by the undercoat coating composition (I), but the coating method is not particularly limited. Examples thereof include spraying, flow coating, roll coating, brush coating, dip coating, spin coating, screen printing, casting, gravure printing, flexographic printing, and the like. Drying after application may be room temperature drying or heat drying.

  The coating thickness of the undercoating coating composition (I) can be arbitrarily changed, but is preferably 5 μ to 500 μ, more preferably 10 μ to 200 μ. The coating thickness of the overcoating coating composition (II) is 0.1 μm to 20 μm, preferably 0.2 μm to 10 μm. When the coating thickness of the overcoating composition (II) is thinner than 0.1 μm, it is difficult to obtain sufficient photocatalytic activity, and when the coating film is thicker than 20 μm, the coating film tends to crack.

  Since excellent weather resistance can be obtained without providing a special protective layer between the undercoat layer and the base material of the multilayer coating film in this embodiment, it is advantageous in terms of simplification of the process. The topcoat layer has photocatalytic activity and is made hydrophilic by photoexcitation, so that excellent stain resistance can be obtained. Furthermore, since the overcoat layer contains colloidal silica, it is possible to maintain hydrophilicity even in the absence of photoexcitation.

  As an application example of the multilayer coating film according to the present embodiment, it is useful as a coating film for outdoor structures such as building materials, building exteriors, window frames, tanks, bridges, and the like. The multi-layer coating film has photocatalytic activity such as organic matter decomposition and develops various functions such as antibacterial, antifouling, deodorant, NOx decomposition, etc. Can be used for applications.

  Hereinafter, the present embodiment will be described more specifically with reference to examples and comparative examples. However, the present embodiment is not limited to these examples.

Evaluation method 1. Number average particle size A sample was diluted by appropriately adding a solvent so that the solid content was 1 to 20% by mass, and measurement was performed using a wet particle size analyzer (Nikkiso Microtrac UPA-9230).

2. Contact angle of water to the surface of the coating film A drop of ion-exchanged water was placed on the surface of the coating film and left at 20 ° C. for 1 minute, and then the contact angle was measured using a CA-X150 contact angle meter manufactured by Kyowa Interface Science. The smaller the contact angle of water with the coating surface, the higher the hydrophilicity of the coating surface.

3. Weather resistance An exposure test is conducted in which a test plate having a multilayer coating film formed on a substrate is exposed to an environment with a black panel temperature of 63 ° C. and a rainfall of 18 minutes / 2 hours using a sunshine weather meter manufactured by Suga Test Instruments. went. The gloss of the coating film was measured before exposure and after 1000 hours of exposure to determine the gloss retention. Further, the contact angle of water on the coating film surface after 1000 hours of exposure was measured by the method of “2.”. The appearance was visually evaluated.

4). Contamination resistance A test plate with a multilayer coating film formed on a base material is attached to a fence facing a general road (truck traffic of about 500 to 1000 units / day) for 3 months, and then the degree of contamination is visually observed. And evaluated.

Undercoat layer 4 parts by mass of ethylene glycol monobutyl ether and 4 parts by mass of ethylene glycol mono-2-ethylhexyl ether were blended with 100 parts by mass of the polymer emulsion for undercoat to obtain a coating composition (I) for undercoat. The obtained coating composition (I) was used as a wire coater No. 50 was applied to an alumite sulfate plate as a substrate and dried at room temperature for 14 days to form an undercoat layer.
Synthesis of polymer emulsion particles (A)

(Synthesis Example A1)
Sulfosuccinic acid diester ammonium salt having in its molecule a double bond copolymerizable with 290 parts by mass of ion-exchanged water and an ethylenically unsaturated monomer in a reaction vessel equipped with a stirrer, reflux condenser, dropping tank and thermometer 10 parts by mass of a 20% by mass aqueous solution (product name: Latemul S-180A, manufactured by Kao Corporation) was added, and the temperature in the reaction vessel was raised to 80 ° C. Subsequently, 10 parts by mass of a 2% by mass aqueous solution of ammonium persulfate was added, and 5 minutes later, 25 parts by mass of methyl methacrylate, 50 parts by mass of cyclohexyl methacrylate, 15 parts by mass of butyl acrylate, 5 parts by mass of methacrylic acid, methacrylic acid An emulsion mixture consisting of 10 parts by weight of 2-hydroxyethyl, 5 parts by weight of 20% by weight aqueous solution of Latemul S-180A, 15 parts by weight of 2% by weight aqueous solution of ammonium persulfate and 48 parts by weight of ion-exchanged water over 40 minutes from the dropping tank. And let it flow in. During the inflow, the temperature of the reaction vessel was kept at 80 ° C. Further, even after the inflow was completed, the temperature of the reaction vessel was kept at 80 ° C. for 30 minutes.

  Next, a mixture of 109 parts by weight of methyl methacrylate, 160 parts by weight of cyclohexyl methacrylate, 123 parts by weight of butyl acrylate and 8 parts by weight of methacrylic acid, 20 parts by weight of a 20% by weight aqueous solution of Latemule S-180A, ammonium persulfate An emulsified mixed liquid composed of 60 parts by mass of a 2% by weight aqueous solution and 192 parts by mass of ion-exchanged water, and a mixed liquid composed of 1 part of 3-methacryloxypropyltrimethoxysilane, 20 parts of dimethyldimethoxysilane and 20 parts of methyltrimethoxysilane. Then, the silicone modification reaction was performed by letting it flow from a separate dropping tank over 160 minutes. The pH during the silicone modification reaction was maintained at 4 or less. During the inflow, the temperature of the reaction vessel was kept at 80 ° C. Furthermore, the temperature of the reaction vessel was raised to 80 ° C. for 120 minutes after the inflow was completed.

  After cooling to room temperature, the hydrogen ion concentration of the reaction solution was measured and found to be pH 2.2. A 25% aqueous ammonia solution was added to adjust the pH to 8, and the reaction solution was filtered through a 100-mesh wire mesh to obtain a polymer emulsion containing polymer emulsion particles A1. The dry mass of the filtered aggregate was a slight 0.05% by mass with respect to the total monomers. The solid content of the obtained polymer emulsion was 44.5% by mass, and the number average particle diameter of the polymer emulsion particles A1 was 100 nm.

(Synthesis Example A2)
Into a reaction vessel equipped with a stirrer, reflux condenser, dropping tank and thermometer, 290 parts by mass of ion-exchanged water and 10 parts by mass of a 20% by mass aqueous solution of Latemul S-180A were added, and the temperature in the reaction vessel was raised to 80 ° C. Raised. Subsequently, 10 parts by mass of a 2% by mass aqueous solution of ammonium persulfate was added, and 5 minutes later, 25 parts by mass of methyl methacrylate, 50 parts by mass of cyclohexyl methacrylate, 15 parts by mass of butyl acrylate, 5 parts by mass of methacrylic acid, methacrylic acid An emulsified mixed solution consisting of 10 parts by mass of 2-hydroxyethyl, 5 parts by mass of a 20% by mass aqueous solution of Latemul S-180A, 15 parts by mass of a 2% by mass aqueous solution of ammonium persulfate, and 48 parts by mass of ion-exchanged water was added from an addition tank. It was allowed to flow in over a minute. During the inflow, the temperature of the reaction vessel was kept at 80 ° C. Further, even after the inflow was completed, the temperature of the reaction vessel was kept at 80 ° C. for 30 minutes.

  Next, a mixture of 109 parts by weight of methyl methacrylate, 160 parts by weight of cyclohexyl methacrylate, 123 parts by weight of butyl acrylate and 8 parts by weight of methacrylic acid, 20 parts by weight of a 20% by weight aqueous solution of Latemule S-180A, ammonium persulfate An emulsified mixture composed of 60 parts by mass of a 2% by weight aqueous solution and 208 parts by mass of ion-exchanged water, 1.2 parts by mass of 3-methacryloxypropyltrimethoxysilane, 45 parts by mass of dimethyldimethoxysilane, and 45 parts by mass of methyltrimethoxysilane The mixed solution consisting of was allowed to flow from a separate dropping tank over 160 minutes to allow the silicone modification reaction to proceed. The pH during the silicone modification reaction was maintained at 4 or less. During the inflow, the temperature of the reaction vessel was kept at 80 ° C. Furthermore, the temperature of the reaction vessel was raised to 80 ° C. for 120 minutes after the inflow was completed.

  After cooling to room temperature, the hydrogen ion concentration of the reaction mixture was measured and found to be pH 2.3. A 25% aqueous ammonia solution was added to adjust the pH to 8, and the reaction solution was filtered through a 100-mesh wire mesh to obtain a polymer emulsion containing polymer emulsion particles A2. The dry mass of the filtered aggregate was as small as 0.07% by mass with respect to the total monomers. The obtained polymer emulsion had a solid content of 45.5% by mass, and the number average particle diameter of the polymer emulsion particles A1 was 115 nm.

(Synthesis Example A3)
In a reaction vessel equipped with a stirrer, reflux condenser, dropping tank and thermometer, 290 parts by mass of ion-exchanged water and 10 parts by mass of a 20% by mass aqueous solution of Latemul S-180A were added, and the temperature in the reaction vessel was brought to 80 ° C. Raised. Subsequently, 10 parts by mass of a 2% by mass aqueous solution of ammonium persulfate was added, and 5 minutes later, 25 parts by mass of methyl methacrylate, 50 parts by mass of cyclohexyl methacrylate, 15 parts by mass of butyl acrylate, 5 parts by mass of methacrylic acid, methacrylic acid An emulsified mixed solution consisting of 10 parts by mass of 2-hydroxyethyl, 5 parts by mass of a 20% by mass aqueous solution of Latemuru S-180A, 15 parts by mass of a 2% by mass aqueous solution of ammonium persulfate, and 48 parts by mass of beautiful ion-exchanged water is added from a dropping tank. It was allowed to flow in over 40 minutes. During the inflow, the temperature of the reaction vessel was kept at 80 ° C. Further, even after the inflow was completed, the temperature of the reaction vessel was kept at 80 ° C. for 30 minutes.

  Next, a mixture of 109 parts by weight of methyl methacrylate, 160 parts by weight of cyclohexyl methacrylate, 123 parts by weight of butyl acrylate and 8 parts by weight of methacrylic acid, 30 parts by weight of a 20% by weight aqueous solution of Latemule S-180A, ammonium persulfate From an emulsified mixed solution composed of 60 parts by mass of a 2% by weight aqueous solution and 305 parts by mass of ion-exchanged water, 1.5 parts by mass of 3-methacryloxypropyltrimethoxysilane, 200 parts by mass of dimethyldimethoxysilane and 130 parts by mass of methyltrimethoxysilane. The resulting mixed liquid was allowed to flow from a separate dropping tank over 160 minutes. The pH during the silicone modification reaction was maintained at 4 or less. During the inflow, the temperature of the reaction vessel was kept at 80 ° C. Furthermore, the temperature of the reaction vessel was raised to 80 ° C. for 120 minutes after the inflow was completed.

  After cooling to room temperature, the hydrogen ion concentration of the reaction solution was measured and found to be pH 2.0. A 25% aqueous ammonia solution was added to adjust the pH to 8, and then the reaction solution was filtered through a 100-mesh wire mesh to obtain a polymer emulsion containing the polymer emulsion A3. The dry mass of the filtered aggregate was as small as 0.10% by mass with respect to the total monomers. The solid content of the obtained polymer emulsion was 45.8% by mass, and the number average particle diameter of the polymer emulsion particles A3 was 121 nm.

(Synthesis Example A4)
In a reaction vessel equipped with a stirrer, reflux condenser, dropping tank and thermometer, 290 parts by mass of ion-exchanged water and 10 parts by mass of a 20% by mass aqueous solution of Latemul S-180A were added, and the temperature in the reaction vessel was brought to 80 ° C. Raised. Subsequently, 10 parts by mass of a 2% by mass aqueous solution of ammonium persulfate was added, and 5 minutes later, 25 parts by mass of methyl methacrylate, 50 parts by mass of cyclohexyl methacrylate, 15 parts by mass of butyl acrylate, 5 parts by mass of methacrylic acid, methacrylic acid An emulsified mixed solution consisting of 10 parts by mass of 2-hydroxyethyl, 5 parts by mass of a 20% by mass aqueous solution of Latemul S-180A, 15 parts by mass of a 2% by mass aqueous solution of ammonium persulfate, and 48 parts by mass of ion-exchanged water was added from an addition tank. It was allowed to flow in over a minute. During the inflow, the temperature of the reaction vessel was kept at 80 ° C. Further, the temperature of the reaction vessel was kept at 80 ° C. for 30 minutes after the inflow was completed.

  Next, 109 parts by weight of methyl methacrylate, 160 parts by weight of cyclohexyl methacrylate, 123 parts by weight of butyl acrylate, 8 parts by weight of methacrylic acid, and isooctyl-3- (3- (2H-benzotriazole-2-2) which is an ultraviolet absorber. Yl) -5-tert-butyl-4-hydroxyphenyl) propionate (Nippon Ciba-Geigy Co., Ltd., trade name: TINUVIN 384) 3 parts by mass, and hindered amine light stabilizer (Nippon Ciba-Geigy Co., Ltd., trade name: TINUVIN 292) ) 3 parts by weight of a mixed solution, 20 parts by weight of a 20% by weight aqueous solution of Latemul S-180A, 60 parts by weight of a 2% by weight aqueous solution of ammonium persulfate and 208 parts by weight of ion-exchanged water, and 3-methacryloxy 1.2 parts by mass of propyltrimethoxysilane, dimethyldimethoxy And a mixture consisting of silane 45 parts by mass 45 parts by mass of methyl trimethoxysilane, by flowing over 160 minutes from separate dropping tanks was allowed to proceed for silicone-modified reaction. The hindered amine light stabilizer is composed of bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate and methyl-1,2,2,6,6-pentamethyl-4-piperidyl-sebacate. It is a mixture. The pH during the silicone modification reaction was maintained at 4 or less. During the inflow, the temperature of the reaction vessel was kept at 80 ° C. Furthermore, the temperature of the reaction vessel was raised to 80 ° C. for 120 minutes after the inflow was completed.

  After cooling to room temperature, the hydrogen ion concentration of the reaction solution was measured and found to be pH 2.5. A 25% aqueous ammonia solution was added to adjust the pH to 8, and the reaction solution was filtered through a 100-mesh wire mesh to obtain a polymer emulsion containing polymer emulsion particles A4. The dry mass of the filtered aggregate was as small as 0.12% by mass with respect to the total monomers. The solid content of the obtained polymer emulsion was 45.7% by mass, and the number average particle size of the polymer emulsion A4 was 118 nm.

(Synthesis Example A5)
In a reaction vessel equipped with a stirrer, reflux condenser, dropping tank and thermometer, 290 parts by mass of ion-exchanged water and 10 parts by mass of a 20% by mass aqueous solution of Latemul S-180A were added, and the temperature in the reaction vessel was brought to 80 ° C. Raised. Subsequently, 10 parts by mass of a 2% by mass aqueous solution of ammonium persulfate was added, and 5 minutes later, 25 parts by mass of methyl methacrylate, 50 parts by mass of cyclohexyl methacrylate, 15 parts by mass of butyl acrylate, 5 parts by mass of methacrylic acid, methacrylic acid An emulsified mixed solution consisting of 10 parts by mass of 2-hydroxyethyl, 5 parts by mass of a 20% by mass aqueous solution of Latemul S-180A, 15 parts by mass of a 2% by mass aqueous solution of ammonium persulfate, and 48 parts by mass of ion-exchanged water was added from an addition tank. It was allowed to flow in over a minute. During the inflow, the temperature of the reaction vessel was kept at 80 ° C. Further, the temperature of the reaction vessel was kept at 80 ° C. for 30 minutes after the inflow was completed.

  Next, a mixture of 109 parts by weight of methyl methacrylate, 160 parts by weight of cyclohexyl methacrylate, 123 parts by weight of butyl acrylate and 8 parts by weight of methacrylic acid, 20 parts by weight of a 20% by weight aqueous solution of Latemule S-180A, ammonium persulfate An emulsified mixed solution composed of 60 parts by mass of a 2% by mass aqueous solution and 192 parts by mass of ion-exchanged water was allowed to flow in over 160 minutes. During the reaction, the pH was maintained at 4 or less. During the inflow, the temperature of the reaction vessel was kept at 80 ° C. Furthermore, the temperature of the reaction vessel was raised to 80 ° C. for 120 minutes after the inflow was completed.

  After cooling to room temperature, the hydrogen ion concentration of the reaction solution was measured and found to be 2.1. A 25% aqueous ammonia solution was added to adjust the pH to 8, and the reaction solution was filtered through a 100-mesh wire mesh to obtain a polymer emulsion containing polymer emulsion particles A5. The dry mass of the filtered aggregate was a slight 0.05% by mass with respect to the total monomers. The solid content of the obtained polymer emulsion was 43.9% by mass, and the number average particle diameter of the polymer emulsion particles A5 was 105 nm.

Synthesis of polymer emulsion particles (C) (Synthesis Example C1)
Into a reactor having a reflux condenser, a dropping tank, a thermometer, and a stirring device, 1600 parts by mass of ion-exchanged water and 2 parts by mass of dodecylbenzenesulfonic acid were added, and the temperature was heated to 80 ° C. with stirring. There, 86 parts by mass of butyl acrylate, 133 parts by mass of phenyltrimethoxysilane and 1.3 parts by mass of 3-methacryloxypropyltrimethoxysilane, 137 parts by mass of diethylacrylamide, 3 parts by mass of acrylic acid, and reactivity A mixed solution of 13 parts by mass of an emulsifier (trade name “Adekaria Soap SR-1025”, manufactured by Asahi Denka Co., Ltd., 25% by mass aqueous solution), 40 parts by mass of a 2% by mass aqueous solution of ammonium persulfate and 1200 parts by mass of ion-exchanged water; Were simultaneously added dropwise over about 2 hours while maintaining the temperature in the reaction vessel at 80 ° C. Further, stirring was continued for about 2 hours while the temperature in the reaction vessel was 80 ° C. Thereafter, the reaction solution was cooled to room temperature and filtered through a 100 mesh wire net. The filtrate was adjusted with ion-exchanged water to a solid content concentration of 10.0% by mass to obtain a polymer emulsion containing polymer emulsion particles C1 having a number average particle diameter of 100 nm.

(Synthesis Example C2)
Into a reactor having a reflux condenser, a dropping tank, a thermometer and a stirrer, 1000 parts by mass of ion-exchanged water and 2 parts by mass of dodecylbenzenesulfonic acid were added, and then the temperature was heated to 80 ° C. with stirring. There, a mixed solution of 86 parts by mass of butyl acrylate, 133 parts by mass of phenyltrimethoxysilane and 1.3 parts by mass of 3-methacryloxypropyltrimethoxysilane, 25 parts by mass of diethylacrylamide, 3 parts by mass of acrylic acid, Adekaria A mixed solution of 13 parts by mass of a 25% by mass aqueous solution of soap SR-1025, 40 parts by mass of a 2% by mass aqueous solution of ammonium persulfate and 800 parts by mass of ion-exchanged water was maintained in a state where the temperature in the reaction vessel was kept at 80 ° C. It was dripped simultaneously over 2 hours. Further, stirring was continued for about 2 hours while the temperature in the reaction vessel was 80 ° C. Thereafter, the reaction solution was cooled to room temperature and filtered through a 100 mesh wire net. The filtrate was adjusted with ion-exchanged water to a solid content concentration of 10.0% by mass to obtain a polymer emulsion containing polymer emulsion particles C2 having a number average particle diameter of 105 nm.

(Synthesis Example C3)
Into a reactor having a reflux condenser, a dropping tank, a thermometer, and a stirring device, 1600 parts by mass of ion-exchanged water and 2 parts by mass of dodecylbenzenesulfonic acid were added, and the temperature was heated to 80 ° C. with stirring. There, 86 parts by mass of butyl acrylate, 2 parts by mass of 2-hydroxyethyl methacrylate, 133 parts by mass of phenyltrimethoxysilane and 1.3 parts by mass of 3-methacryloxypropyltrimethoxysilane, and N-isopropylacrylamide 137 parts by mass, 2 parts by mass of acrylic acid, 13 parts by mass of a 25% by mass aqueous solution of Adeka Soap SR-1025, 40 parts by mass of a 2% by mass aqueous solution of ammonium persulfate and 1200 parts by mass of ion-exchanged water were mixed in a reaction vessel. It was dripped simultaneously over about 2 hours in the state which maintained the inside temperature at 80 degreeC. Further, stirring was continued for about 2 hours while the temperature in the reaction vessel was 80 ° C. Thereafter, the reaction solution was cooled to room temperature and filtered through a 100 mesh wire net. The filtrate was adjusted with ion-exchanged water to a solid content concentration of 10.0% by mass to obtain a polymer emulsion containing polymer emulsion particles C3 having a number average particle diameter of 110 nm.

(Synthesis Example C4)
Into a reactor having a reflux condenser, a dropping tank, a thermometer, and a stirring device, 1600 parts by mass of ion-exchanged water and 2 parts by mass of dodecylbenzenesulfonic acid were added, and the temperature was heated to 80 ° C. with stirring. There, a mixed solution of 86 parts by mass of butyl acrylate and 133 parts by mass of phenyltrimethoxysilane, 137 parts by mass of diethylacrylamide, 3 parts by mass of acrylic acid, 13 parts by mass of a 25% by mass aqueous solution of Adecalia Soap SR-1025, A mixed solution of 40 parts by mass of a 2% by mass aqueous solution of ammonium sulfate and 1200 parts by mass of ion-exchanged water was simultaneously added dropwise over about 2 hours while maintaining the temperature in the reaction vessel at 80 ° C. Further, stirring was continued for about 2 hours while the temperature in the reaction vessel was 80 ° C. Thereafter, the reaction solution was cooled to room temperature and filtered through a 100 mesh wire net. The filtrate was adjusted to a solid content concentration of 10.0% by mass with ion-exchanged water to obtain a polymer emulsion containing polymer emulsion particles C4 having a number average particle diameter of 122 nm.

(Synthesis Example C5)
Into a reactor having a reflux condenser, a dropping tank, a thermometer, and a stirring device, 1600 parts by mass of ion-exchanged water and 4 parts by mass of dodecylbenzenesulfonic acid were added, and then the temperature was heated to 80 ° C. with stirring. Thereto, a liquid mixture of 185 parts by mass of dimethyldimethoxysilane and 117 parts by mass of phenyltrimethoxysilane was dropped over about 2 hours while maintaining the temperature in the reaction vessel at 80 ° C., and then the temperature in the reaction vessel was Stirring was continued for about 1 hour at 80 ° C. Next, a mixed solution of 86 parts by mass of butyl acrylate, 133 parts by mass of phenyltrimethoxysilane and 1.3 parts by mass of 3-methacryloxypropyltrimethoxysilane, 137 parts by mass of diethylacrylamide, 3 parts by mass of acrylic acid, and ADEKA rear soap A mixed liquid of 13 parts by mass of a 25% by mass aqueous solution of SR-1025, 40 parts by mass of a 2% by mass aqueous solution of ammonium persulfate and 1900 parts by mass of ion-exchanged water was maintained at about 2 with the temperature in the reaction vessel maintained at 80 ° C. It was dripped simultaneously over time. Further, stirring was continued for about 2 hours while the temperature in the reaction vessel was 80 ° C., and then the reaction solution was cooled to room temperature and filtered through a 100-mesh wire mesh. The filtrate was adjusted with ion-exchanged water to a solid content concentration of 10.0% by mass to obtain a polymer emulsion containing polymer emulsion particles C5 having a number average particle diameter of 130 nm.

(Synthesis Example C6)
Into a reactor having a reflux condenser, a dropping tank, a thermometer and a stirrer, 1000 parts by mass of ion-exchanged water and 2 parts by mass of dodecylbenzenesulfonic acid were added, and then the temperature was heated to 80 ° C. with stirring. There, 86 parts by mass of butyl acrylate, 137 parts by mass of diethyl acrylamide, 3 parts by mass of acrylic acid, 13 parts by mass of 25% by mass aqueous solution of Adekari Soap SR-1025, 40 parts by mass of 2% by mass aqueous solution of ammonium persulfate and ion exchange A mixed solution of 500 parts by mass of water was simultaneously added dropwise over about 2 hours in a state where the temperature in the reaction vessel was kept at 80 ° C. Further, stirring was continued for about 2 hours while the temperature in the reaction vessel was 80 ° C., and then the reaction solution was cooled to room temperature and filtered through a 100-mesh wire mesh. The filtrate was adjusted to a solid concentration of 10.0% by mass with ion-exchanged water to obtain a polymer emulsion containing polymer emulsion particles C6 having a number average particle diameter of 85 nm.

(Synthesis Example C7)
Into a reactor having a reflux condenser, a dropping tank, a thermometer, and a stirring device, 1600 parts by mass of ion-exchanged water and 2 parts by mass of dodecylbenzenesulfonic acid were added, and the temperature was heated to 80 ° C. with stirring. There, 86 parts by weight of butyl acrylate, 133 parts by weight of phenyltrimethoxysilane, 1.3 parts by weight of 3-methacryloxypropyltrimethoxysilane, 137 parts by weight of methyl methacrylate, 3 parts by weight of acrylic acid, Adekaria soap SR- A mixture of 13 parts by weight of 25% by weight aqueous solution of 1025, 40 parts by weight of 2% by weight aqueous solution of ammonium persulfate and 1200 parts by weight of ion-exchanged water was maintained for about 2 hours while maintaining the temperature in the reaction vessel at 80 ° C. It was dripped simultaneously. Further, stirring was continued for about 2 hours while the temperature in the reaction vessel was 80 ° C., and then the reaction solution was cooled to room temperature and filtered through a 100-mesh wire mesh. The filtrate was adjusted to a solid concentration of 10.0% by mass with ion-exchanged water to obtain a polymer emulsion containing polymer emulsion particles C7 having a number average particle diameter of 107 nm.

Example 1
16 parts by mass of water-dispersed colloidal silica having a number average particle size of 12 nm (trade name “Snowtex O”, manufactured by Nissan Chemical Industries, Ltd., solid content 20% by mass ) in 40 parts by mass of the polymer emulsion obtained in Synthesis Example C1; And 2.5 parts by mass of silica-coated titanium oxide hydrosol having a number average particle size of 10 nm (trade name “MPT-422”, manufactured by Ishihara Sangyo Co., Ltd., solid content 20% by mass ), and stirring, overcoating A composition was obtained.

  Using this overcoat coating composition, the polymer emulsion obtained in Synthesis Example A4 was used as the undercoat polymer emulsion, and the dry film thickness was 2 μm on the undercoat layer formed on the sulfated alumite plate by the method described above. It was applied by bar coating. The coating film was dried at room temperature for 1 week to form a multilayer coating film composed of an undercoat layer and an overcoat layer.

  The water contact angle of the obtained multilayer coating film was 21 degrees. Even after 3 months of the contamination resistance test, no visual contamination was observed. The gloss retention after exposure for 1000 hours of the sunshine weatherometer was 86%. The water contact angle after exposure was 10 degrees, and no cracks were observed visually.

(Example 2)
40 parts by mass of the polymer emulsion obtained in Synthesis Example C5, 16 parts by mass of water-dispersed colloidal silica Snowtex O (solid content 20% by mass) having a number average particle diameter of 12 nm, and silica-coated titanium oxide hydro having a number average particle diameter of 10 nm 2.5 parts by mass of sol MPT-422 (solid content: 20% by mass) was mixed and stirred to obtain a top coating composition.

  Using this overcoat coating composition, the polymer emulsion obtained in Synthesis Example A1 was used as the undercoat polymer emulsion, and the dry film thickness was 2 μm on the undercoat layer formed on the sulfated alumite plate by the method described above. It was applied by bar coating. The coating film was dried at room temperature for 1 week to obtain a multilayer coating film composed of an undercoat layer and an overcoat layer.

  The water contact angle of the obtained multilayer coating film was 31 degrees. Even after 3 months of the contamination resistance test, no visual contamination was observed. The gloss retention after 1000 hours of exposure to the sunshine weatherometer was 79%. The water contact angle after exposure was 12 degrees, and only minute cracks were observed visually.

(Example 3)
40 parts by mass of the polymer emulsion obtained in Synthesis Example C1, 16 parts by mass of water-dispersed colloidal silica Snowtex O (solid content 20% by mass) having a number average particle diameter of 12 nm, and silica-coated titanium oxide hydro having a number average particle diameter of 10 nm 2.5 parts by mass of sol MPT-422 (solid content: 20% by mass) was mixed and stirred to obtain a top coating composition.

  Using this overcoat coating composition, the polymer emulsion obtained in Synthesis Example A3 was used as the undercoat polymer emulsion, and the dry film thickness was 2 μm on the undercoat layer formed on the sulfated alumite plate by the above-described method. It was applied by bar coating. The coating film was dried at room temperature for 1 week to obtain a multilayer coating film composed of an undercoat layer and an overcoat layer.

  The water contact angle of the obtained multilayer coating film was 21 degrees. Even after 3 months of the contamination resistance test, no visual contamination was observed. The gloss retention after exposure for 1000 hours of the sunshine weatherometer was 82%. The water contact angle after exposure was 8 degrees, and no cracks were observed visually.

Example 4
40 parts by mass of the polymer emulsion obtained in Synthesis Example C5, 16 parts by mass of water-dispersed colloidal silica Snowtex O (solid content 20% by mass) having a number average particle diameter of 12 nm, and silica-coated titanium oxide hydro having a number average particle diameter of 10 nm 5 parts by mass of sol MPT-422 (solid content 20% by mass) was mixed and stirred to obtain a top coating composition.

  Using this polymer coating composition obtained in Synthesis Example A4 as a polymer emulsion for undercoating, a dry film thickness of 1.5 μm was formed on the undercoating layer formed on the alumite sulfate plate by the above-described method. It applied by the bar coat so that it might become. The coating film was dried at room temperature for 1 week to obtain a multilayer coating film composed of an undercoat layer and an overcoat layer.

  The resulting multilayer coating film had a water contact angle of 18 degrees. Even after 3 months of the contamination resistance test, no visual contamination was observed. The gloss retention after 1000 hours of exposure to the sunshine weatherometer was 90%. The water contact angle after exposure was 7 degrees, and no cracks were observed visually.

(Example 5)
40 parts by mass of the polymer emulsion obtained in Synthesis Example C1, 16 parts by mass of water-dispersed colloidal silica Snowtex O (solid content 20% by mass) having a number average particle diameter of 12 nm, and silica-coated titanium oxide hydro having a number average particle diameter of 10 nm 2.5 parts by mass of sol MPT-422 (solid content: 20% by mass) was mixed and stirred to obtain a top coating composition.

  Using this overcoat coating composition, the polymer emulsion obtained in Synthesis Example A1 was used as the undercoat polymer emulsion, and the dry film thickness was 2 μm on the undercoat layer formed on the sulfated alumite plate by the method described above. It was applied by bar coating. The coating film was dried at room temperature for 1 week to obtain a multilayer coating film composed of an undercoat layer and an overcoat layer.

  The water contact angle of the obtained multilayer coating film was 23 degrees. Even after 3 months of the contamination resistance test, no visual contamination was observed. The gloss retention after exposure for 1000 hours of the sunshine weatherometer was 78%. The water contact angle after exposure was 10 degrees, and only minute cracks were visually observed.

(Example 6)
40 parts by mass of the polymer emulsion obtained in Synthesis Example C1, 16 parts by mass of water-dispersed colloidal silica Snowtex O (solid content 20% by mass) having a number average particle diameter of 12 nm, and silica-coated titanium oxide hydro having a number average particle diameter of 10 nm 2.5 parts by mass of sol MPT-422 (solid content: 20% by mass) was mixed and stirred to obtain a top coating composition.

  Using this polymer coating composition obtained in Synthesis Example A2 as a polymer emulsion for undercoating, this overcoating coating composition has a dry film thickness of 2 μm on the undercoating layer formed on the sulfated alumite plate by the above-described method. It was applied by bar coating. The coating film was dried at room temperature for 1 week to obtain a multilayer coating film composed of an undercoat layer and an overcoat layer.

  The resulting multilayer coating film had a water contact angle of 25 degrees. Even after 3 months of the contamination resistance test, no visual contamination was observed. The gloss retention after exposure for 1000 hours of the sunshine weatherometer was 73%. The water contact angle after exposure was 15 degrees, and only minute cracks were visually observed.

(Example 7)
40 parts by mass of the polymer emulsion obtained in Synthesis Example C2, 16 parts by mass of water-dispersed colloidal silica Snowtex O (solid content 20% by mass) having a number average particle size of 12 nm, and silica-coated titanium oxide hydro having a number average particle size of 10 nm 2.5 parts by mass of sol MPT-422 (solid content: 20% by mass) was mixed and stirred to obtain a top coating composition.

  Using this overcoat coating composition, the polymer emulsion obtained in Synthesis Example A1 was used as the undercoat polymer emulsion, and the dry film thickness was 2 μm on the undercoat layer formed on the sulfated alumite plate by the method described above. It was applied by bar coating. The coating film was dried at room temperature for 1 week to obtain a multilayer coating film composed of an undercoat layer and an overcoat layer.

  The water contact angle of the obtained multilayer coating film was 20 degrees. Even after 3 months of the contamination resistance test, no visual contamination was observed. The gloss retention after exposure for 1000 hours of the sunshine weatherometer was 75%. The water contact angle after exposure was 9 degrees, and only minute cracks were visually observed.

(Example 8)
40 parts by mass of the polymer emulsion obtained in Synthesis Example C3, 16 parts by mass of water-dispersed colloidal silica Snowtex O (solid content 20% by mass) having a number average particle size of 12 nm, and silica-coated titanium oxide hydro having a number average particle size of 10 nm 2.5 parts by mass of sol MPT-422 (solid content: 20% by mass) was mixed and stirred to obtain a top coating composition.

  Using this overcoat coating composition, the polymer emulsion obtained in Synthesis Example A1 was used as the undercoat polymer emulsion, and the dry film thickness was 1 μm on the undercoat layer formed on the alumite sulfate plate by the above-described method. It was applied by bar coating. The coating film was dried at room temperature for 1 week to obtain a multilayer coating film composed of an undercoat layer and an overcoat layer.

  The water contact angle of the obtained multilayer coating film was 27 degrees. Even after 3 months of the contamination resistance test, no visual contamination was observed. The gloss retention after exposure for 1000 hours of the sunshine weatherometer was 77%. The water contact angle after exposure was 16 degrees, and only minute cracks were visually observed.

Example 9
40 parts by mass of the polymer emulsion obtained in Synthesis Example C4, 16 parts by mass of water-dispersed colloidal silica Snowtex O (solid content 20% by mass) having a number average particle diameter of 12 nm, and silica-coated titanium oxide hydro having a number average particle diameter of 10 nm 3.75 parts by mass of sol MPT-422 (solid content 20% by mass) was mixed and stirred to obtain a top coating composition.

  Using this overcoat coating composition, the polymer emulsion obtained in Synthesis Example A1 was used as the undercoat polymer emulsion, and the dry film thickness was 2 μm on the undercoat layer formed on the sulfated alumite plate by the method described above. It was applied by bar coating. The coating film was dried at room temperature for 1 week to obtain a multilayer coating film composed of an undercoat layer and an overcoat layer.

  The water contact angle of the obtained multilayer coating film was 21 degrees. Even after 3 months of the contamination resistance test, no visual contamination was observed. The gloss retention after exposure for 1000 hours by the sunshine weatherometer was 70%. The water contact angle after exposure was 8 degrees, and only minute cracks were visually observed.

(Example 10)
40 parts by mass of the polymer emulsion obtained in Synthesis Example C7, 16 parts by mass of water-dispersed colloidal silica Snowtex O (solid content 20% by mass) having a number average particle size of 12 nm, and silica-coated titanium oxide hydro having a number average particle size of 10 nm 2.5 parts by mass of sol MPT-422 (solid content: 20% by mass) was mixed and stirred to obtain a top coating composition.

  Using this overcoat coating composition, the polymer emulsion obtained in Synthesis Example A1 was used as the undercoat polymer emulsion, and the dry film thickness was 2 μm on the undercoat layer formed on the sulfated alumite plate by the method described above. It was applied by bar coating. The coating film was dried at room temperature for 1 week to obtain a multilayer coating film composed of an undercoat layer and an overcoat layer.

  The water contact angle of the obtained multilayer coating film was 26 degrees. Even after 3 months of the contamination resistance test, no visual contamination was observed. The gloss retention after exposure for 1000 hours of the sunshine weatherometer was 77%. The water contact angle after exposure was 12 degrees, and only minute cracks were observed visually.

(Comparative Example 1)
40 parts by mass of the polymer emulsion obtained in Synthesis Example C1, 16 parts by mass of water-dispersed colloidal silica Snowtex O (solid content 20% by mass) having a number average particle diameter of 12 nm, and silica-coated titanium oxide hydro having a number average particle diameter of 10 nm 2.5 parts by mass of sol MPT-422 (solid content: 20% by mass) was mixed and stirred to obtain a top coating composition.

  Using this overcoat coating composition, the polymer emulsion obtained in Synthesis Example A5 was used as the undercoat polymer emulsion, and the dry film thickness was 2 μm on the undercoat layer formed on the sulfated alumite plate by the method described above. It was applied by bar coating. The coating film was dried at room temperature for 1 week to obtain a multilayer coating film composed of an undercoat layer and an overcoat layer.

  The water contact angle of the obtained multilayer coating film was 22 degrees. Even after 3 months of the contamination resistance test, no visual contamination was observed. The gloss retention after 1000 hours of exposure to the sunshine weatherometer was as low as 40%, and the coating film surface was peeled off. The water contact angle after exposure was as high as 40 degrees.

(Comparative Example 2)
40 parts by mass of the polymer emulsion obtained in Synthesis Example C6, 16 parts by mass of water-dispersed colloidal silica Snowtex O (solid content 20% by mass) having a number average particle size of 12 nm, and silica-coated titanium oxide hydro having a number average particle size of 10 nm 2.5 parts by mass of sol MPT-422 (solid content: 20% by mass) was mixed and stirred to obtain a top coating composition.

  Using this overcoat coating composition, the polymer emulsion obtained in Synthesis Example A1 was used as the undercoat polymer emulsion, and the dry film thickness was 2 μm on the undercoat layer formed on the sulfated alumite plate by the method described above. It was applied by bar coating. The coating film was dried at room temperature for 1 week to obtain a multilayer coating film composed of an undercoat layer and an overcoat layer.

  The water contact angle of the obtained multilayer coating film was 19 degrees. Even after 3 months of the contamination resistance test, no visual contamination was observed. The gloss retention after 1000 hours exposure of the sunshine weatherometer was as low as 38%, and the coating film surface was peeled off. The water contact angle after exposure was as high as 43 degrees.

(Comparative Example 3)
Into 40 parts by mass of the polymer emulsion obtained in Synthesis Example C1, 16 parts by mass of water-dispersed colloidal silica Snowtex O (solid content of 20% by mass) having a number average particle size of 12 nm is blended and stirred to form a top coating composition. Obtained.

  Using this overcoat coating composition, the polymer emulsion obtained in Synthesis Example A1 was used as the undercoat polymer emulsion, and the dry film thickness was 2 μm on the undercoat layer formed on the sulfated alumite plate by the method described above. It was applied by bar coating. The coating film was dried at room temperature for 1 week to obtain a multilayer coating film composed of an undercoat layer and an overcoat layer.

  The water contact angle of the obtained multilayer coating film was 26 degrees. Contamination was confirmed by visual observation after 3 months of the stain resistance test. The gloss retention after 1000 hours of exposure to the sunshine weatherometer was 86%, and no cracks were observed on the surface. The water contact angle after exposure was as high as 42 degrees.

(Comparative Example 4)
40 parts by mass of the polymer emulsion obtained in Synthesis Example C1 is mixed with 2.5 parts by mass of silica-coated titanium oxide hydrosol MPT-422 (solid content of 20% by mass) having a number average particle size of 10 nm, and the mixture is stirred and overcoated. A composition was obtained.

  Using this overcoat coating composition, the polymer emulsion obtained in Synthesis Example A1 was used as the undercoat polymer emulsion, and the dry film thickness was 2 μm on the undercoat layer formed on the sulfated alumite plate by the method described above. It was applied by bar coating. The coating film was dried at room temperature for 1 week to obtain a multilayer coating film composed of an undercoat layer and an overcoat layer.

  The water contact angle of the obtained multilayer coating film was 46 degrees. Slight contamination was visually observed after 3 months of the stain resistance test. The gloss retention after exposure for 1000 hours of the sunshine weatherometer was 78. The water contact angle after exposure was 13 degrees, and only minute cracks were observed visually.

  In each of Examples 1 to 10, the undercoat paint and the overcoat paint use a polymer emulsion using a hydrolyzable silicon compound as a raw material, and show good weather resistance. Among these, when an ultraviolet absorber and a light stabilizer are contained as in Example 1 and Example 4, the weather resistance is particularly excellent. Those having a high silicon content in the polymer emulsion used in the undercoat paint as in Example 3 are also excellent in weather resistance. Moreover, the polymer emulsion used for the top coat as in Example 2 and Example 4 having a core-shell structure also shows excellent weather resistance.

  On the other hand, when the undercoat paint uses a polymer emulsion that does not use a hydrolyzable silicon compound as a raw material, and the top coat paint uses a polymer emulsion that does not use a hydrolyzable silicon compound as a raw material, the weather resistance is inferior (comparison) Example 1 and Comparative Example 2). When the top coat does not contain a photocatalyst as in Comparative Example 3, the weather resistance is good but the contamination is poor. Moreover, when the top coat does not contain colloidal silica as in Comparative Example 4, the initial water contact angle is large and the initial coating tends to be contaminated.

  The multilayer coating film provided by the present invention is an excellent coating film having both stain resistance and weather resistance, and is useful as a coating film for building exteriors, outdoor structures and the like.

It is sectional drawing which shows one Embodiment of a multilayer coating film.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Multilayer coating film, 2 ... Base material, 11 ... Undercoat layer, 12 ... Topcoat layer.

Claims (4)

An undercoat layer, and an overcoat layer provided on the undercoat layer,
The undercoat containing the polymer emulsion particles (A) having a core / shell structure obtained by a method comprising a step of polymerizing a vinyl monomer and a hydrolyzable silicon compound in the presence of water and an emulsifier, respectively. Is a film formed by drying the coating film of the coating composition (I) for coating,
A core / shell structure obtained by a method in which the overcoat layer comprises a step of polymerizing a metal oxide particle (B) having photocatalytic activity and a vinyl monomer and a hydrolyzable silicon compound in the presence of water and an emulsifier, respectively. a polymer emulsion particles having a (C), is a film a coating film is formed by drying the colloidal silica (D), top coat coating composition containing (II),
Multi-layer coating.   In the polymer emulsion particles (A), in the presence of water and an emulsifier, a vinyl monomer and a hydrolyzable silicon compound are mixed at a mass ratio of vinyl monomer / hydrolyzable silicon compound = 95/5 to 50/50. The multilayer coating film according to claim 1, which is obtained by a method including a step of polymerizing each.   The multilayer coating film according to claim 1 or 2, wherein the undercoating coating composition (I) further contains an ultraviolet absorber and / or a light stabilizer. A vinyl monomer and a hydrolyzable silicon compound, wherein the polymer emulsion particles (C) include an amide group-containing vinyl monomer having a secondary amide group and / or a tertiary amide group in the presence of water and an emulsifier. Obtained by a method comprising polymerizing each of
The mass ratio of the amide group-containing vinyl monomer to the polymer emulsion particles (C) is the amide group-containing vinyl monomer / the polymer emulsion particles (C) = 10/90 to 70/30. The multilayer coating film as described in any one of Claims 1-3.

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