Film formation method

Abstract

To provide a film formation method capable of securing excellent coating workability under various coating conditions.SOLUTION: A film formation method coats a first coating material and a second coating material onto a base material, wherein the first coating material contains epoxy resin emulsion (A), an amino group-containing resin (B) and an aqueous resin (C) (excluding (A) and (B)), the second coating material contains an aqueous resin (E) having a functional group having reactivity to an amino group, and the second coating material is coated by at least one applicator selected from a brush and a roller.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a novel method for forming a coating. [Background technology]

[0002] In painting interior and exterior walls and floors of buildings, various undercoat materials are selected and used in consideration of adhesion to the substrate. Conventionally, such undercoat materials have been mainly solvent-based, but recently, water-based undercoat materials have been adopted in consideration of the environment, safety, etc. For example, Patent Document 1 describes a two-liquid reactive curing water-based paint composition for undercoat paint, which is composed of a base agent containing an epoxy resin emulsion and a curing agent containing an amine resin.

[0003] However, when a topcoat material is applied to such an epoxy resin-based undercoat material with a brush or roller, depending on the painting conditions such as low temperature or high humidity, the painting workability may be poor. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2018-53028 A Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention has been made in consideration of the above problems, and has as its object to provide a coating formation method which is excellent in coating workability under various coating conditions. [Means for solving the problem]

[0006] As a result of extensive research into these problems, the inventors have discovered a coating formation method in which a specific first coating and a specific second coating material are applied to a substrate, and have completed the present invention.

[0007] That is, the present invention has the following features. 1. A first coating material is applied to the substrate. Then, A coating method for sequentially applying a second coating material, comprising: the first coating material contains an epoxy resin emulsion (A), an amino group-containing resin (B), and an aqueous resin (C) (excluding (A) and (B)); a mixing weight ratio (solid content) of the epoxy resin emulsion (A) to the aqueous resin (C) is (A) / (C)<1, and the second coating material is Contains one or more functional groups selected from the group consisting of carboxyl, epoxy and isocyanate groups. The second coating material is applied with at least one application tool selected from the group consisting of a brush and a roller. Effect of the Invention

[0008] The coating film forming method of the present invention can ensure excellent coating workability under various coating conditions. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] The present invention relates to a coating method for applying a first coating material and a second coating material to a substrate. First, the first coating material and the second coating material will be described.

[0010] <First covering material> The first coating material of the present invention is an aqueous coating material comprising an epoxy resin emulsion (A), an amino group-containing resin (B), and an aqueous resin (C) (excluding (A) and (B)). The epoxy resin emulsion (A) of the present invention (hereinafter also simply referred to as "component (A)") is obtained by dispersing / emulsifying an epoxy resin in an aqueous medium. When dispersing an epoxy resin in an aqueous medium, an emulsifier or the like can be used as necessary. The aqueous medium is a medium that mainly contains water, and may contain water-soluble solvents such as lower alcohols, polyhydric alcohols, ether compounds, ester compounds, and alkylene oxide-containing compounds as necessary.

[0011] The epoxy resin of the component (A) may be any epoxy resin that can be dispersed in an aqueous medium, and may be either a solid epoxy resin and / or a liquid epoxy resin. For example, a resin containing at least one epoxy group, preferably at least two epoxy groups, in the molecule may be used, and examples of such an epoxy resin include aromatic epoxy resins, aliphatic epoxy resins, alicyclic epoxy resins, polybutadiene resins having epoxy groups, and polyurethane resins having epoxy groups. In the present invention, aromatic epoxy resins are preferred, and examples thereof include bisphenol A type epoxy resins, bisphenol AD ​​type epoxy resins, bisphenol F type epoxy resins, and novolac type epoxy resins. Among these, at least one selected from bisphenol A type epoxy resins, bisphenol AD ​​type epoxy resins, and bisphenol F type epoxy resins are particularly preferred. Furthermore, the epoxy resin may be one whose molecular weight has been increased as necessary, a fatty acid-modified epoxy resin obtained by reacting a fatty acid, or one obtained by making an amine-added epoxy resin (amine-modified epoxy resin) obtained by addition reaction of an amino group-containing compound water-soluble. These may be used alone or in combination of two or more. In addition, a solid epoxy resin refers to one that is solid at room temperature (23°C), and a liquid epoxy resin refers to one that is liquid at room temperature (23°C).

[0012] In the present invention, the component (A) preferably includes a solid epoxy resin (a1) as an essential component. Examples of such an embodiment include an embodiment containing only the solid epoxy resin (a1) and an embodiment containing the solid epoxy resin (a1) and the liquid epoxy resin (a2). This allows the effects of the present invention to be fully achieved. When the solid epoxy resin (a1) and the liquid epoxy resin (a2) are mixed, the mixing ratio (solids weight ratio) is preferably 100:0 to 5:95 (more preferably 100:0 to 10:90), depending on the epoxy equivalent of each epoxy resin. In the present invention, "α to β" is synonymous with "α or more and β or less".

[0013] The method for preparing the component (A) is not particularly limited, but may be, for example, a method in which a solid epoxy resin and / or a liquid epoxy resin is mixed with an emulsifier as necessary to prepare a resin solution, and then the solution is mixed with an aqueous medium (containing an emulsifier as necessary) to emulsify the solution. In addition, the above preparation may be heated as necessary. In the present invention, when a solid epoxy resin and a liquid epoxy resin are used in combination, it is preferable to prepare aqueous dispersions of the solid epoxy resin and the liquid epoxy resin, and then mix them together for use. The resin solid content of the epoxy resin aqueous dispersion is not particularly limited, but is preferably 10 to 80% by weight (more preferably 20 to 70% by weight).

[0014] As the emulsifier, for example, anionic surfactants and nonionic surfactants can be used either alone or in combination. Examples of the anionic surfactant include alkali metal sulfonates such as sodium dodecylbenzenesulfonate, sodium laurylnaphthalenesulfonate, and sodium stearyl diphenyl ether disulfonate; and alkali metal sulfates such as sodium lauryl sulfate, polyoxyethylene lauryl ether sodium sulfate, and polyoxyethylene octylphenyl ether sodium sulfate. Examples of nonionic surfactants include polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, and oxyethylene-oxypropylene block copolymers. The amount of the emulsifier to be added is preferably within the range of 0.1 to 15% by weight (more preferably 0.1 to 10% by weight, and even more preferably 0.5 to 5% by weight) based on the resin solid content.

[0015] The average particle size of the epoxy resin water dispersion of component (A) of the present invention is not particularly limited, but is preferably 100 to 1000 nm (more preferably 150 to 900 nm, even more preferably 200 to 800 nm, and particularly preferably 300 to 600 nm). If the average particle size is within such a range, advantageous effects can be obtained in terms of sealing properties, efflorescence resistance, whitening resistance, and the like. The average particle size referred to here is a value measured by a dynamic light scattering method.

[0016] The component (A) of the present invention has an epoxy equivalent x a However, the epoxy equivalent x is preferably 100 to 3000 (more preferably 110 to 2000, and further preferably 120 to 1500). a " is the number of grams of resin solids containing 1 gram equivalent of epoxy groups [g / eq], and is the value obtained by dividing the weight average molecular weight of the epoxy resin by the number of epoxy groups per molecule.

[0017] In addition, the above component (A) has an epoxy equivalent x a It is also possible to use a mixture of particles having different sizes and average particle sizes.

[0018] The amino group-containing resin (B) of the present invention (hereinafter, simply referred to as "component (B)") reacts with the epoxy resin emulsion (A) to form a coating film. As the component (B), for example, a polyamine resin containing two or more amino groups in one molecule can be used, and examples thereof include aliphatic polyamines, alicyclic polyamines, aromatic polyamines, heterocyclic amines, and modified polyamine resins obtained by modifying the amino groups of these polyamine resins. In addition, known methods can be used to modify the polyamine resin, and examples thereof include amidation of amino groups, Mannich reaction of amino groups with carbonyl compounds, addition reaction of amino groups with epoxy groups, and addition reaction of amino groups with styrene. In addition, as the component (B), aliphatic polyamides, alicyclic polyamides, aromatic polyamides, aliphatic polyamidoamines, alicyclic polyamidoamines, aromatic polyamidoamines, etc. can also be used. These can be used alone or in combination of two or more.

[0019] In the present invention, it is preferable that the (B) component contains at least one selected from, for example, aliphatic polyamines and modified aliphatic polyamines. This improves adhesion and adhesion to substrates and coatings when mixed with an epoxy resin emulsion. Examples of aliphatic polyamines include chain aliphatic polyamines such as diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, dipropylenediamine, diethylaminopropylamine, and hexamethylenediamine; cyclic aliphatic polyamines such as N-aminoethylpiperazine, bis(4-amino-3-methylcyclohexyl)methane, menthenediamine, isophoronediamine, 4,4'-diaminodicyclohexylmethane, 3,9-bis(3-aminopropyl)-2,4,8,10-tetraoxaspiro[5.5]undecane (spiroacetaldiamine), norbornanediamine, tricyclodecanediamine, and 1,3-bisaminomethylcyclohexane; and aliphatic aromatic amines such as metaxylenediamine. In the present invention, it is particularly preferable that the monomer contains at least one selected from meta-xylylenediamine and a styrene addition reaction product of meta-xylylenediamine.

[0020] The embodiment of the (B) component is not particularly limited, but a water-soluble resin that can be dissolved in an aqueous medium, or a water-dispersed resin that can be dispersed in an aqueous medium, can be used. In the present invention, it is preferable that the (B) component contains a water-soluble resin. In this case, the storage stability is excellent, and compatibility and reactivity with the epoxy resin emulsion (A) are increased, and the adhesion and adhesion to the substrate and the coating film are further improved, and a coating film excellent in water resistance and coating film appearance can be formed. The (B) component may be a solvent-free type (solid content 100% by weight) or may be a type in which the (B) component is dissolved or dispersed in an aqueous medium in advance. The solid content of the (B) component is preferably 50% by weight or more (more preferably 55% by weight or more, and even more preferably 60% by weight or more). The upper limit of the solid content of the (B) component is 100% by weight or less. When this range is satisfied, the effects of the present invention can be fully exhibited. The aqueous medium is a medium that mainly contains water, and may contain water-soluble solvents such as lower alcohols, polyhydric alcohols, ether compounds, ester compounds, and alkylene oxide-containing compounds, as necessary.

[0021] In addition, the active hydrogen equivalent y of the component (B) is b is preferably 10 to 1000 (more preferably 50 to 800, and further preferably 80 to 600). b " is the number of grams of resin solids containing 1 gram equivalent of active hydrogen groups [g / eq], and is the value obtained by dividing the weight average molecular weight of the amino group-containing resin by the number of hydrogen atoms of the amino group per molecule.

[0022] In the first coating material of the present invention, the component (A) and the component (B) are mixed at an epoxy equivalent ([X A ]: solid content equivalent) and the active hydrogen equivalent of the above component (B) ([Y B ] (solid content equivalent) ratio [X A / (Y BIt is preferable to mix so that the ratio (ratio) of the first coating material and the second coating material is preferably 0.1 to 3 (more preferably 0.0.5 to 2, and even more preferably 0.7 to 1.5). In such a case, the adhesion and adhesion of the first coating material to the substrate and coating film are improved. Furthermore, the stability and usable life of the first coating material can be increased.

[0023] In addition, the above X A , the above Y B is determined from the blending parts at the time of mixing, and specifically, the above [X A ] is the amount of component (A) contained in the base resin (solid weight parts) multiplied by the epoxy equivalent of component (A) x a In addition, the above [Y B is the amount of component (B) contained in the curing agent (parts by weight of solid content) expressed as the active hydrogen equivalent y b This is the value divided by .

[0024] The first coating material of the present invention is characterized in that it contains an aqueous resin (C) (excluding (A) and (B)) in addition to the above-mentioned (A) and (B). By containing the aqueous resin (C) (hereinafter also simply referred to as "component (C)"), the influence of the coating conditions can be suppressed and the coating workability of the second coating material can be sufficiently ensured. Although the mechanism of action is not limited, it is considered that since component (C) is likely to be present near the surface of the formed coating film, excessive reaction between the first coating material and the second coating material can be suppressed when the second coating material is applied, and as a result, excellent coating workability can be ensured when the second coating material is applied with a brush, roller, or the like. In addition, by containing the above-mentioned component (C), it is possible to suppress amine brushing, etc., and to form a coating film that exhibits excellent adhesion to various substrates and coating films and is excellent in water resistance, coating film appearance, etc.

[0025] In the present invention, the mixing weight ratio (solid content) of the above-mentioned (A) component to the above-mentioned (C) component is preferably (A) / (C)<1 (more preferably <0.9, and even more preferably <0.8). The lower limit is not particularly limited as long as the component (A) is contained, but is preferably 0.1<(A) / (C) (more preferably 0.2<(A) / (C)). By containing the component (C) at such a mixing ratio, the concentration of the component (C) tends to be high near the surface of the formed coating film, and as a result, the above-mentioned effects can be further enhanced.

[0026] The above-mentioned (C) component (excluding the above-mentioned (A) component and the above-mentioned (B) component) is not particularly limited as long as it is soluble or dispersible in an aqueous medium, and a known resin can be used. Examples of such resins include acrylic resins, urethane resins, silicone resins, fluororesins, vinyl acetate resins, polyester resins, alkyd resins, vinyl chloride resins, and the like, or composites thereof. These can be used alone or in combination of two or more. Furthermore, as the (C) component, a water-dispersible resin (resin emulsion) in which the above-mentioned resin components are dispersed in an aqueous medium is suitable. The aqueous medium is a medium mainly containing water, and may be mixed with a water-soluble solvent such as a lower alcohol, a polyhydric alcohol, an ether compound, an ester compound, or an alkylene oxide-containing compound, as necessary.

[0027] In the present invention, it is preferable that the component (C) contains an acrylic resin emulsion (C1) (hereinafter, also simply referred to as "component (C1)"). In such a component (C1), an alkyl (meth)acrylate ester is the main component of the resin skeleton, and other monomers and other polymerizable monomers are copolymerized as necessary. In the present invention, alkyl acrylate ester and alkyl methacrylate ester are collectively referred to as alkyl (meth)acrylate ester. Furthermore, "monomer" is a general term for compounds having a polymerizable unsaturated double bond.

[0028] In the present invention, it is preferable that the monomer group constituting the component (C1) contains a hydrophobic monomer, for example, a long-chain alkyl (meth)acrylate, an aromatic group-containing monomer, or the like.

[0029] As the long-chain alkyl (meth)acrylate, an alkyl (meth)acrylate having an alkyl group having 4 or more carbon atoms can be used, for example, n-butyl (meth)acrylate, t-butyl (meth)acrylate, isobutyl (meth)acrylate, n-hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, decyl (meth)acrylate, dodecyl (meth)acrylate, octadecyl (meth)acrylate, cyclohexyl (meth)acrylate, etc. These can be used alone or in combination of two or more.

[0030] Examples of aromatic group-containing monomers include styrene-based monomers such as styrene, 2-methylstyrene, vinyltoluene, ethylvinylbenzene, vinylnaphthalene, and chlorostyrene, and aromatic group-containing (meth)acrylates such as phenyl(meth)acrylate, benzyl(meth)acrylate, and phenoxyethyl(meth)acrylate, etc. These may be used alone or in combination of two or more.

[0031] In the present invention, a particularly preferred embodiment is one in which the hydrophobic monomer contains an alkyl (meth)acrylate having an alkyl group with 6 or more carbon atoms (preferably 8 or more carbon atoms).

[0032] The content of the hydrophobic monomer in the monomer group is preferably 10% by weight or more, more preferably 30% by weight or more, and even more preferably 40% by weight or more, in terms of weight ratio. The upper limit is not particularly limited, but is preferably 99.5% by weight or less. In this case, the compatibility with the organic solvent (O) described below is improved, and the effects of the present invention can be enhanced.

[0033] Specific examples of the other monomers include amide group-containing monomers, carbonyl group-containing monomers, carboxyl group-containing monomers, amino group-containing monomers, epoxy group-containing monomers, hydroxyl group-containing monomers, vinylidene halide monomers, alkoxysilyl group-containing monomers, ethylene, propylene, isoprene, butadiene, vinyl ether, vinyl ketone, etc. These can be used alone or in combination of two or more.

[0034] In the present invention, it is preferable to include an epoxy group-containing monomer. Examples of the epoxy group-containing monomer include glycidyl (meth)acrylate, diglycidyl fumarate, 3,4-epoxycyclohexyl (meth)acrylate, 3,4-epoxyvinylcyclohexane, allyl glycidyl ether, ε-caprolactone-modified glycidyl (meth)acrylate, and β-methylglycidyl (meth)acrylate. These can be used alone or in combination of two or more.

[0035] In the present invention, the content of the epoxy group-containing monomer in the monomers constituting the component (C1) is preferably 0.5 to 50% by weight (more preferably 1 to 30% by weight), which suppresses the decrease in adhesion and whitening of the coating film caused by amine blushing, and allows the coating film to exhibit sufficient physical properties.

[0036] Other specific examples of monomers include: Examples of nitrile group-containing monomers include (meth)acrylonitrile, vinylidene cyanide, and α-cyanoethyl (meth)acrylate. Examples of the amide group-containing monomer include maleic acid amide, (meth)acrylamide, N-monoalkyl (meth)acrylamide, N,N-dialkyl (meth)acrylamide, 2-(dimethylamino)ethyl (methacrylate), N-[3-(dimethylamino)propyl] (meth)acrylamide, and vinylamide. Examples of the carbonyl group-containing monomer include acrolein, diacetone (meth)acrylamide, vinyl methyl ketone, vinyl ethyl ketone, and vinyl butyl ketone. Examples of the carboxyl group-containing monomer include (meth)acrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid, isocrotonic acid, and salicylic acid. Examples of amino group-containing monomers include aminomethyl acrylate, aminoethyl acrylate, aminopropyl (meth)acrylate, amino-n-butyl (meth)acrylate, butylvinylbenzylamine, vinylphenylamine, p-aminostyrene, N-methylaminoethyl (meth)acrylate, and Nt-butylaminoethyl (meth)acrylate. Examples of hydroxyl group-containing monomers include hydroxypropyl (meth)acrylate, ethylene glycol mono(meth)acrylate, and glycerol mono(meth)acrylate. Examples of vinylidene halide monomers include vinylidene fluoride, etc. Examples of the alkoxysilyl group-containing monomer include vinyltrimethoxysilane, vinyltriethoxysilane, γ-(meth)acryloyloxypropyltrimethoxysilane, γ-(meth)acryloyloxypropyltriethoxysilane, γ-(meth)acryloyloxypropylmethyldimethoxysilane, etc. These can be used alone or in combination of two or more.

[0037] The (C1) component can be produced by emulsion polymerization of a monomer group obtained by appropriately mixing the above monomers. Any known method can be used as the polymerization method, and in addition to normal emulsion polymerization, soap-free emulsion polymerization, feed emulsion polymerization, seed emulsion polymerization, multi-stage emulsion polymerization, etc. can also be used. During polymerization, for example, emulsifiers, initiators, dispersants, polymerization inhibitors, polymerization retarders, buffers, chain transfer agents, pH adjusters, etc. can be used.

[0038] As the emulsifier, various surfactants that can be used in emulsion polymerization can be used, and these may be reactive types (reactive surfactants) having polymerizable unsaturated double bonds. As the emulsifier, for example, anionic surfactants and nonionic surfactants can be used alone or in combination. Specifically, for example, they can be appropriately selected from those described in the above component (A).

[0039] The glass transition temperature (hereinafter simply referred to as "Tg") of the component (C1) can be adjusted by selecting the type and mixing ratio of the monomers. This Tg may be appropriately set in consideration of the final required performance, etc., but it is preferable that the component (C1) has a Tg of -5 to 80°C (more preferably -3 to 60°C). Two or more components with different Tgs can also be used as the component (C1). In this case, it is preferable that the total Tg falls within the above range. The glass transition temperature can be calculated using Fox's formula.

[0040] The average particle size of the component (C1) is not particularly limited, but is preferably 300 nm or less (more preferably 20 to 250 nm, and even more preferably 30 to 200 nm). If the average particle size is within this range, advantageous effects can be obtained in terms of impregnation reinforcement, sealing properties, efflorescence resistance, whitening resistance, and the like. In addition, two or more types of component (C1) having different average particle sizes can also be used. The average particle size referred to here is a value measured by dynamic light scattering.

[0041] In the present invention, it is preferable that the ratio of the average particle size of the (A) component to the (C1) component is (A) / (C1)>1 (more preferably >1.2). This tends to increase the concentration of the (C1) component near the surface of the formed coating film, thereby suppressing the effects of coating conditions and enabling the coating film to exhibit even better physical properties. When the (A) component and the (C1) component contain two or more different average particle sizes, it is preferable that the average value of the average particle size of the (A) component and the average value of the average particle size of the (C1) component satisfy the above condition.

[0042] The embodiment of the first coating material is not particularly limited as long as it contains the above-mentioned component (A), component (B), and component (C). For example, An embodiment including the component (A), the component (B), and the component (C) (one-component type), A two-part type having a base agent containing the component (A) and a curing agent containing the component (B), in which either the base agent or the curing agent, or both, contain the above-mentioned component (C); An embodiment (three-component type) having a base agent containing the component (A), a curing agent containing the component (B), and a third component containing the component (C), etc. In the case where mutually reactive components are allowed to coexist, for example, a prescription of masking, blocking, etc. can be adopted. The first coating material of the present invention is preferably of the above-mentioned two-liquid type, and is particularly preferably an aqueous coating material having a base agent containing components (A) and (C) and a curing agent containing component (B).

[0043] In addition to the above components, the first coating material of the present invention preferably contains an organic solvent (O) (hereinafter, simply referred to as "component (O)") having a boiling point of 200°C or higher and a solubility in water of 10g / 100gH2O or less at 20°C. By further containing component (O) in addition to component (C), the compatibility and reactivity of components (A), (B), and (C) are enhanced, and excellent film-forming properties can be obtained. As a result, a dense coating film can be formed, the effects of coating conditions can be efficiently suppressed, amine blushing and the like are less likely to occur, and the coating workability of the second coating material can be improved.

[0044] The above-mentioned (O) component can be mixed into either the base agent or the curing agent (or the third component), or into both (all of them), but in the present invention, it is preferable to mix it into the base agent, which further enhances the above-mentioned effects and allows the formation of a coating film with excellent aesthetics in which amine blushing and the like are suppressed.

[0045] The (O) component is not particularly limited as long as it is an organic solvent having a boiling point of 200° C. or higher and a solubility in water of 10 g / 100 g / 100 gH2O or less at 20° C., and examples thereof include ethylene glycol ether compounds such as ethylene glycol monohexyl ether, ethylene glycol dibutyl ether, and ethylene glycol phenyl ether; diethylene glycol ether compounds such as diethylene glycol monohexyl ether, diethylene glycol monobutyl ether acetate, and diethylene glycol dibutyl ether; propylene glycol ether compounds such as propylene glycol phenyl ether, dipropylene glycol-n-butyl ether, dipropylene glycol-tert-butyl ether, dipropylene glycol-n-propyl ether, and tripropylene glycol-n-butyl ether; 2-ethyl-1,3-hexanediol, 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, 2,2,4-trimethyl-1,3-pentanediol diisobutyrate, and benzyl alcohol. These can be used alone or in combination of two or more. The boiling point of component (O) is 200° C. or higher, with the upper limit being preferably 350° C. or lower (more preferably 300° C. or lower). The solubility of component (O) in water at 20° C. is 10 g / 100 g H2O or lower, preferably 8 g / 100 g H2O or lower, with the lower limit being preferably 0 g / 100 g H2O or higher (more preferably 0.1 g / 100 g H2O or higher).

[0046] In the present invention, it is particularly preferable to contain at least one propylene glycol ether compound such as propylene glycol phenyl ether, dipropylene glycol-n-butyl ether, dipropylene glycol-tert-butyl ether, dipropylene glycol-n-propyl ether, and tripropylene glycol-n-butyl ether.

[0047] The mixing amount of the component (O) is preferably 1 to 80 parts by weight (more preferably 2 to 60 parts by weight) per 100 parts by weight of the component (A) (solid content). Within this range, the above effects can be fully exhibited.

[0048] Furthermore, the first coating material of the present invention may contain a silane compound (S). Examples of the silane compound (S) include a glycidyl group-containing silane compound (S1), an alkoxysilane compound (S2), and an amino group-containing silane compound (S3). These may be used alone or in combination of two or more.

[0049] As the glycidyl group-containing silane compound (S1) (hereinafter also simply referred to as "component (S1)"), a compound having a glycidyl group (epoxy group) and an alkoxysilyl group, or a compound having a glycidyl group and a cyclic siloxane, etc., can be used. These can be used alone or in combination of two or more.

[0050] Examples of the compound having a glycidyl group (epoxy group) and an alkoxysilyl group include a glycidyl group-containing silane coupling agent and a hydrolyzed oligomer thereof.

[0051] Specifically, examples of the glycidyl group-containing silane coupling agent include glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, β-glycidoxyethyltrimethoxysilane, β-glycidoxyethyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyldimethylmethoxysilane, γ-glycidoxypropyl(ethyl)dimethoxysilane, β-3,4-epoxycyclohexylethyltrimethoxysilane, β-3,4-epoxycyclohexylethyltriethoxysilane, 8-glycidoxyoctyltrimethoxysilane, 8-glycidoxyoctylmethyldimethoxysilane, 8-glycidoxyoctylmethyldiethoxysilane, and the like. Preferably, the glycidyl group-containing silane coupling agent has an epoxy equivalent of x n1 The epoxy equivalent x is preferably 10 to 1000 (more preferably 50 to 500). n1" is the number of grams of a silane compound containing 1 gram equivalent of an epoxy group [g / eq], and is the value obtained by dividing the weight average molecular weight of a glycidyl group-containing silane compound by the number of epoxy groups per molecule.

[0052] The hydrolysis oligomer of the glycidyl group-containing silane coupling agent has an alkoxysilyl group and a glycidyl group, and preferably has an alkoxy group content of 10 to 80 wt % (more preferably 20 to 75 wt %) and an epoxy equivalent x n1 The (N1) component may have two or more types of alkoxysilyl groups, or may have all or some of the alkoxysilyl groups in a silanol group state.

[0053] The compound having a glycidyl group and a cyclic siloxane is a silicone oligomer having only a glycidyl group as a reactive functional group, and preferably has an epoxy equivalent of x n1 is 100 to 500 (more preferably 150 to 400).

[0054] In particular, in the present invention, as the above-mentioned (S1) component, a glycidyl group-containing silane coupling agent is preferred, for example, one or more selected from glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, β-glycidoxyethyltrimethoxysilane, β-glycidoxyethyltriethoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β-3,4-epoxycyclohexylethyltrimethoxysilane, and β-3,4-epoxycyclohexylethyltriethoxysilane are preferred, and an embodiment including one or more selected from β-3,4-epoxycyclohexylethyltrimethoxysilane and β-3,4-epoxycyclohexylethyltriethoxysilane is more preferred. When these are used, the adhesion development and adhesion to the substrate and coating film are further improved. Furthermore, the stability and usable time of the aqueous coating material can be increased.

[0055] When the (S1) component is contained, it is preferable to mix it with the main agent (or the third component), and the mixing ratio is preferably 0.5 to 50 parts by weight (more preferably 1 to 40 parts by weight) of the (S1) component per 100 parts by weight of the (A) component (solid content). In such a case, the adhesion to the substrate and the coating film is enhanced, and the adhesion is further improved. Furthermore, the stability and usable life of the aqueous coating material can be increased.

[0056] As the alkoxysilane compound (S2) (hereinafter also simply referred to as "component (S2)"), alkoxysilane and its hydrolysis condensate can be used. These can be used alone or in combination of two or more. By using such a component (S2), it is possible to further increase the adhesion to the substrate.

[0057] Examples of such component (S2) include tetrafunctional alkoxysilane compounds such as tetraethoxysilane, tetramethoxysilane, tetra-n-propoxysilane, tetraisopropoxysilane, tetraisobutoxysilane, tetra-sec-butoxysilane, tetra-t-butoxysilane, and tetraphenoxysilane;

[0058] trifunctional alkylalkoxysilane compounds such as methyltrimethoxysilane, methyltriethoxysilane, methyltrippropoxysilane, methyltributoxysilane, ethyltrimethoxysilane, ethyltriethoxysilane, ethyltrippropoxysilane, ethyltributoxysilane, propyltrimethoxysilane, propyltriethoxysilane, propyltrippropoxysilane, propyltributoxysilane, butyltrimethoxysilane, butyltriethoxysilane, butyltrippropoxysilane, butyltributoxysilane, hexyltrimethoxysilane, hexyltriethoxysilane, decyltrimethoxysilane, trifluoropropyltrimethoxysilane, phenyltrimethoxysilane, phenyltriethoxysilane, and phenyltributoxysilane;

[0059] bifunctional alkylalkoxysilane compounds such as dimethyldimethoxysilane, dimethyldiethoxysilane, dimethyldibutoxysilane, diethyldimethoxysilane, diethyldiethoxysilane, diethyldibutoxysilane, diethyldipropoxysilane, dipropyldimethoxysilane, dipropyldiethoxysilane, dibutyldimethoxysilane, dibutyldiethoxysilane, diphenyldimethoxysilane, diphenyldiethoxysilane, diphenyldibutoxysilane, dimethoxymethylphenylsilane, and methylphenyldiethoxysilane; These may be used alone or in combination of two or more.

[0060] In the present invention, the (S2) component preferably contains a trifunctional alkylalkoxysilane compound and / or a bifunctional alkylalkoxysilane compound. Furthermore, it is preferable to contain one containing a phenyl group. Examples of such (S2) components include phenyltrimethoxysilane, dimethoxymethylphenylsilane, diphenyldimethoxysilane, phenyltriethoxysilane, diphenyldiethoxysilane, phenyltributoxysilane, and diphenyldibutoxysilane. When these are used, the curing properties of the formed coating film are increased, and the adhesion and adhesion to the substrate and coating film are further improved. In particular, it can exhibit excellent effects in improving the adhesion and adhesion to the substrate having an existing coating film.

[0061] When the (S2) component is contained, it can be mixed with either the base agent or the curing agent (or the third component), or both (all), but in the present invention, it is preferable to mix it with the base agent, and the mixing ratio is preferably 0.5 to 30 parts by weight (more preferably 1 to 20 parts by weight) of the (S2) component per 100 parts by weight of the (A) component (solid content). In such a case, the above effects can be fully exhibited.

[0062] As the amino group-containing silane compound (S3) (hereinafter also simply referred to as "component (S3)"), a compound having an amino group and an alkoxysilyl group, or a compound having an amino group and a cyclic siloxane, etc., can be used. These can be used alone or in combination of two or more.

[0063] Examples of the compound having an amino group and an alkoxysilyl group include an amino group-containing silane coupling agent, a hydrolyzed oligomer thereof, and a polymer having an alkoxysilyl group and an amino group. Specific examples of the amino group-containing silane coupling agent include: γ-Aminopropyltrimethoxysilane, γ-Aminopropyltriethoxysilane, γ-Aminopropyltriisopropoxysilane, γ-Aminopropylmethyldimethoxysilane, γ-Aminopropylmethyldiethoxysilane, N-β(aminoethyl)-γ-aminopropyltrimethoxysilane, N-β(aminoethyl)-γ-aminopropylmethyldimethoxysilane, N-β(aminoethyl)-γ-aminopropyltriethoxysilane, N-β(aminoethyl)-γ-aminopropylmethyldiethoxysilane, N-β(aminoethyl) )-γ-aminopropyltriisopropoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, γ-ureidopropyltrimethoxysilane, γ-anilinopropyltrimethoxysilane, γ-ureidopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-vinylbenzyl-γ-aminopropyltriethoxysilane, N-β(aminoethyl)-8-aminooctyltrimethoxysilane, γ-triethoxysilyl-N-(1,3-dimethyl-butylidene)propylamine, and the like.

[0064] As the hydrolysis oligomer of the amino group-containing silane coupling agent, those having an alkoxysilyl group and an amino group can be used. As such component (S3), those in which some or all of the alkoxysilyl groups have been converted to silanol groups can also be used.

[0065] In particular, in the present invention, as the component (S3), an amino group-containing silane coupling agent is preferred, such as one or more selected from γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, N-β(aminoethyl)-γ-aminopropylmethyldimethoxysilane, and N-β(aminoethyl)-γ-aminopropylmethyldiethoxysilane. When these are used, the adhesion to the substrate and the coating film is improved.

[0066] In addition, the above component (S3) has an active hydrogen equivalent y m However, the active hydrogen equivalent y is preferably 10 to 500 (more preferably 20 to 400, and further preferably 30 to 300). m " is the number of grams [g / eq] of an amino group-containing silane compound containing 1 gram equivalent of active hydrogen groups, and is the value obtained by dividing the weight average molecular weight of the amino group-containing silane compound by the number of hydrogen atoms of the amino group per molecule.

[0067] When the (S3) component is contained, it is preferably mixed with a curing agent, and the mixing ratio is preferably 0.5 to 200 parts by weight (more preferably 1 to 100 parts by weight) of the (S3) component per 100 parts by weight of the (A) component (solid content). When this range is satisfied, the storage stability is excellent, and the adhesiveness and adhesion to the substrate and coating film can be sufficiently exhibited.

[0068] In the present invention, it is preferable to mix a catalyst (P) (hereinafter, simply referred to as "component (P)"). Component (P) promotes, for example, the reaction between a glycidyl group (epoxy group) and an amino group in the aqueous coating material, or the hydrolysis and condensation of an alkoxysilyl group, and can further improve adhesion to a substrate, particularly adhesion to a substrate having an existing coating film.

[0069] Examples of the component (P) include various aromatic carboxylic acids such as benzoic acid, salicylic acid, trihydroxybenzoic acid, phthalic acid, cinnamic acid, and benzenehexacarboxylic acid; tertiary amines such as trimethylamine, ethyldimethylamine, propyldimethylamine, N,N'-dimethylpiperazine, pyridine, picoline, 1,8-diazabiscyclo(5,4,0)undecene-1 (DBU), benzyldimethylamine, 2-(dimethylaminomethyl)phenol (DMP-10), and 2,4,6-tris(dimethylaminomethyl)phenol (DMP-30); hydroxyamines such as hydroxylamine and phenoxyamine; Examples of the imidazoles include silamines, imidazole, 1-methylimidazole, 2-methylimidazole, 4(5)-methylimidazole, 2-ethyl-4-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, and other imidazoles (B) and amines other than the above component (S3); phenols such as phenol novolac, o-cresol novolac, p-cresol novolac, t-butylphenol novolac, and dicyclopentadiene cresol; and organometallic compounds such as tin octylate, dibutyltin dilaurate, dibutyltin diacetate, organotitanate, and sodium acetate. These can be used alone or in combination of two or more. Among these, as the component (P), particularly preferred are organotin compounds such as tin octoate, dibutyltin dilaurate, and dibutyltin diacetate; and various aromatic carboxylic acids such as benzoic acid, salicylic acid, trihydroxybenzoic acid, phthalic acid, cinnamic acid, and benzenehexacarboxylic acid.

[0070] The (P) component can be mixed with either the base agent or the curing agent (or the third component), or both (all), and the amount mixed is preferably 0.01 to 15 parts by weight (more preferably 0.02 to 10 parts by weight) per 100 parts by weight of the (A) component (solid content). When the amount is within such a range, the effects of the present invention can be enhanced.

[0071] In addition to the above-mentioned components, the first coating material of the present invention may contain, as necessary, color pigments, extender pigments, anti-rust pigments, pH adjusters, plasticizers, preservatives, anti-mold agents, anti-algae agents, defoamers, leveling agents, dispersants, anti-settling agents, anti-sagging agents, thickeners (thixotropic adjusters), film-forming assistants, matting agents, crosslinking agents, catalysts, curing accelerators, adhesion agents, ultraviolet absorbers, light stabilizers, etc., mixed into either the base agent or the curing agent (or the third component), or both (all) within a range that does not significantly impair the effects of the present invention. The first coating material can be manufactured by uniformly mixing the above-mentioned components by a conventional method.

[0072] As the first coating material of the present invention, various materials can be used, such as colored or uncolored, or opaque or transparent. In the present invention, it can be preferably used as a clear type aqueous coating material having transparency. Furthermore, the aqueous coating material of the present invention preferably has a solid content of 5 to 60% by weight (more preferably 6 to 50% by weight, and even more preferably 7 to 45% by weight). The solid content can be adjusted by mixing the above-mentioned aqueous medium. When it is within such a range, it is possible to achieve excellent coating workability and further improve adhesion to various substrates and coating films.

[0073] <Second covering material> The second coating material of the present invention is characterized in that it contains, as an essential component, an aqueous resin (D) (hereinafter, also simply referred to as "component (D)") that contains a functional group reactive with an amino group.

[0074] The component (D) in the present invention is not particularly limited as long as it has a functional group reactive with an amino group and can be dissolved or dispersed in an aqueous medium, and a known resin can be used. Examples of such resins include acrylic resins, urethane resins, silicone resins, fluororesins, vinyl acetate resins, polyester resins, alkyd resins, vinyl chloride resins, and the like, or composites thereof. These can be used alone or in combination of two or more. Furthermore, the component (D) is preferably a water-dispersible resin (resin emulsion) in which the above-mentioned resin components are dispersed in an aqueous medium. In the present invention, it is preferable to include at least one selected from acrylic resin emulsions, urethane resin emulsions, silicone resin emulsions, fluororesin emulsions, and composite resin emulsions thereof. The aqueous medium is a medium mainly containing water, and may be mixed with a water-soluble solvent such as a lower alcohol, a polyhydric alcohol, an ether compound, an ester compound, or an alkylene oxide-containing compound, as necessary.

[0075] Examples of functional groups reactive with amino groups in component (D) include epoxy groups, carboxyl groups, isocyanate groups, and oxazolinyl groups. These may be contained alone or in combination. In the present invention, it is preferable to contain one or more selected from epoxy groups, carboxyl groups, and isocyanate groups, and it is particularly preferable to contain a carboxyl group. By containing such component (D), it is possible to achieve excellent adhesion to the first coating material, and to improve water resistance, durability, and the like. In addition, it is possible to ensure good coating workability for the first coating material.

[0076] The carboxyl group-containing resin emulsion can be obtained by copolymerizing a carboxyl group-containing monomer, such as an ethylenically unsaturated carboxylic acid, such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid, etc., and an ammonium salt, an organic amine salt, an alkali metal salt, etc., of these monomers. One or more of these monomers can be used.

[0077] The method for producing the component (D) is not particularly limited, and examples of the method that can be used include emulsion polymerization, soap-free emulsion polymerization, dispersion polymerization, feed emulsion polymerization, feed dispersion polymerization, seed emulsion polymerization, seed dispersion polymerization, etc. The amount of the reactive functional group in (D) is usually 0.1 to 40% by weight, and preferably 0.5 to 20% by weight, based on the total amount of monomers constituting the component (D).

[0078] The second coating material may contain color pigments, extender pigments, aggregates, etc., as components other than the above-mentioned (D). By appropriately mixing such components, it is possible to express a desired color or texture. In addition, various additives that can be used in normal paints may also be mixed. Examples of such additives include thickeners, film-forming assistants, leveling agents, wetting agents, plasticizers, antifreeze agents, pH adjusters, preservatives, antifungal agents, anti-algae agents, antibacterial agents, dispersants, defoamers, adsorbents, ultraviolet absorbers, antioxidants, fibers, catalysts, etc. The second coating material may be manufactured by uniformly mixing the above-mentioned components by a conventional method.

[0079] <Film formation method> The coating film forming method of the present invention is characterized in that the first coating material and the second coating material are applied in that order to a surface to be coated.

[0080] Examples of the substrate include interior and exterior wall and floor surfaces of buildings, outdoor floor surfaces such as general sidewalks, pedestrian bridges, and platforms, and steel structures such as bridges and steel towers. Specific examples include mortar, concrete, ceramic siding boards, ceramic siding boards, metal siding boards, extrusion molding boards, slate boards, calcium silicate boards, ALC boards, metals, wood, glass, ceramics, and synthetic resins. In addition, the surfaces of these may be those on which a wide variety of existing coating films and the like have been formed. Furthermore, the shapes of such substrates and existing coating films include those that are smooth (flat) and those that have various uneven patterns (for example, stone-like, brick / tile-like, wood-grain-like, border-like, plastered wall-like, sprayed-on, etc.). Furthermore, the present invention can also be applied to substrates including sealing joints.

[0081] In particular, the coating method of the present invention is suitable as a coating method for repairing a substrate, and can be suitably applied as a coating method for repairing, for example, a siding board having an existing coating film.

[0082] The existing coating film is a coating film that has already been applied on the substrate by on-site painting or factory painting (line painting), and examples thereof include at least one coating film selected from organic coating films, inorganic coating films, and organic-inorganic composite coating films. Examples of the existing coating film include colored coating films (enamel coating films, printed coating films, etc.), clear coating films, and laminated coating films thereof, and are coating films formed by applying and curing various coating materials to the substrate. Such coating materials may be any of room temperature drying type, room temperature curing type, bake curing type, ultraviolet (UV) curing type, electron beam curing type, etc.

[0083] Examples of binders for such coating materials include organic binders such as acrylic resin, polyurethane resin, epoxy resin, fluororesin, alkyd resin, and polyester resin; inorganic binders such as silicone resin, alkoxysilane, colloidal silica, and silicate; and organic-inorganic composite binders such as acrylic silicone resin.

[0084] The present invention is particularly suitable when the existing coating film is one or more selected from inorganic coating films (coating films containing the above-mentioned inorganic binder), organic-inorganic composite coating films (coating films containing the above-mentioned organic-inorganic composite binder), fluororesin coating films (coating films containing the above-mentioned fluororesin), etc., and can further be suitably applied to clear coating films thereof. Such existing coating films may contain photocatalytic titanium oxide, etc.

[0085] Specific examples of coating materials include weather-resistant topcoat paints for architecture (JIS K5658:2010), weather-resistant paints for steel structures (JIS K5659:2008), glossy synthetic resin emulsion paints (JIS K5660:2008), fire-retardant paints for architecture (JIS K5661:1970), synthetic resin emulsion paints (JIS K5663:2008), road marking paints (JIS K5665:2011), multicolored pattern paints (JIS K5667:2003), synthetic resin emulsion pattern paints (JIS K5668:2010), acrylic resin-based non-aqueous dispersion paints (JIS K5670:2008), lead- and chromium-free rust-preventive paints (JIS K5674:2008), high solar reflectance paints for roofs (JIS K5675:2011), and floor paints for buildings (JIS K5970:2008), architectural coating waterproofing materials (JIS A6021:2011), architectural finishing coating materials (JIS A6909:2014), etc.

[0086] The method for applying the first coating material to the substrate is not particularly limited, and various methods can be used, such as brush coating, roller coating, spray coating, etc. When coating is performed in a factory, a roll coater, a flow coater, etc. can also be used in addition to the above.

[0087] The amount of the first coating material applied is preferably 0.05 to 0.5 kg / m 2 (More preferably 0.07 to 0.3 kg / m 2 ) The number of coats of the first coating material may be appropriately determined depending on the condition of the base, but is preferably 1 to 2 coats. The drying time of the first coating material is preferably 1 hour or more and 1 week or less. The drying temperature is preferably -10°C or more and 50°C or less (more preferably -5°C or more and 40°C or less). The first coating material of the present invention is preferably a room temperature curing type.

[0088] The second coating material of the present invention is characterized in that it is applied with at least one applicator selected from a paintbrush, a roller, and a brush. In the present invention, when an applicator that comes into contact with the surface to be coated and applies the second coating material is used, excellent coating workability can be obtained.

[0089] The amount of the second coating material applied is preferably 0.05 to 0.5 kg / m 2 (More preferably 0.07 to 0.3 kg / m 2 ) The number of times the second coating material is applied may be appropriately set as desired, but is preferably 1 to 2 times. The drying time of the second coating material is preferably 1 hour to 1 week. The drying temperature is preferably -10°C to 50°C (more preferably -5°C to 40°C). The second coating material of the present invention is preferably a room temperature curing type.

[0090] The timing for applying the second coating material may be after the first coating material is dry to the touch, but it may also be after semi-curing or curing. The present invention is also effective when the first coating material is dry to the touch and before curing or when the first coating material is dry to the touch and before semi-curing.

[0091] The present invention is also effective when the first coating material and / or the second coating material is dried at least in a low-temperature environment. A low-temperature environment means an environment with an air temperature of 15° C. or lower, and in the present invention, the coating can also be formed in an environment with a lower temperature, for example, an environment with an air temperature of 0 to 10° C. EXAMPLES

[0092] The following examples and comparative examples will clarify the features of the present invention.

[0093] <First covering material> The base material was prepared by mixing epoxy resin emulsion (A), acrylic resin emulsion (C), organic solvent (O), glycidyl group-containing silane compound (S1), alkylalkoxysilane compound (S2), catalyst (P), additives, and water in the mixing ratio shown in Table 1. The curing agent was prepared by mixing amino group-containing resin (B1) and amino group-containing silane compound (S3) in the mixing ratio shown in Table 1. The mixtures of the base material and the curing agent were designated as first coating materials 1 to 12.

[0094] The following raw materials were used: Epoxy resin emulsion (A) (A1) Epoxy resin emulsion [bisphenol A type epoxy resin (solid type) water dispersion, solid content 46% by weight, average particle size: 390 nm, epoxy equivalent x a 508] Amino group-containing resin (B) (B1) Polyamine resin [water-soluble, styrene addition reaction product of meta-xylenediamine, solid content 100% by weight, active hydrogen equivalent y b :103] Acrylic resin emulsion (C) (C1) Acrylic resin emulsion [styrene / 2-ethylhexyl acrylate / glycidyl methacrylate copolymer, glass transition temperature: 20°C, solid content: 33% by weight, glycidyl methacrylate content: 9% by weight, average particle size: 75 nm] (C2) Acrylic resin emulsion [styrene / 2-ethylhexyl acrylate / glycidyl methacrylate copolymer, glass transition temperature: -3°C, solid content: 33% by weight, glycidyl methacrylate content: 9% by weight, average particle size: 160 nm] (C3) Acrylic silicone resin emulsion [methyl methacrylate / n-butyl acrylate / glycidyl methacrylate / 3-methacryloyloxypropyltrimethoxysilane / acrylic acid copolymer, glass transition temperature: 20°C, solid content: 33% by weight, alkoxysilyl group-containing monomer content: 1% by weight, glycidyl methacrylate content: 2% by weight, average particle size: 120 nm] (C4) Acrylic resin emulsion [styrene / 2-ethylhexyl acrylate / methacrylate copolymer, glass transition temperature: 20°C, solid content: 33% by weight, average particle size: 75 nm] Organic solvent (O) (O1) Dipropylene glycol-n-butyl ether [boiling point 229°C, solubility in water at 20°C 5g / 100gH2O] (O2) Propylene glycol [boiling point 187°C, solubility in water at 20°C is ∞] Silane compounds (S) (S1) Glycidyl group-containing silane compound [β-3,4-epoxycyclohexylethyltrimethoxysilane, epoxy equivalent x n1 :246] (S2) Alkylalkoxysilane compound [phenyltrimethoxysilane / dimethoxymethylphenylsilane mixture] (S3) Amino group-containing silane compound [N-β(aminoethyl)-γ-aminopropylmethyldimethoxysilane, active hydrogen equivalent y m :103] ·Catalyst (P) (P1) Organotin compound dispersion [solid content: 10% by weight] Additives: Antifoaming agents, thickeners, etc.

[0095] [Table 1]

[0096] <Second covering material> The second coating material was prepared by uniformly mixing 200 parts by weight of aqueous resin (D) [carboxyl group-containing acrylic resin emulsion (methyl methacrylate / 2-ethylhexyl acrylate / methacrylic acid copolymer, methacrylic acid content: 1% by weight), solid content 50% by weight, average particle size 130 nm], 85 parts by weight of titanium oxide, and 10 parts by weight of additives (dispersant, thickener, defoamer, film-forming aid).

[0097] (Examples 1 to 11, Comparative Example 1) <Creating test specimens> On a siding board with an inorganic clear coating formed as the existing coating, the first coating material obtained by mixing the base agent and hardener was applied with a roller at a rate of 0.1 kg / m 2 The mixture was applied immediately after mixing so as to obtain the above composition, and then dried under the following drying conditions (1) to (5). Next, the second coating material was applied using a roller (short-pile roller) at a rate of 0.1 kg / m 2 The coating was applied so that the coating was as described above, and the coating was allowed to dry for one day under standard conditions (temperature 23°C, relative humidity 50%). The first coating material and the second coating material were applied under standard conditions. (Drying conditions) (1) 7 days under standard conditions (2) 1 hour under standard conditions (3) 2 hours at 5°C and 50% relative humidity

[0098] <Painting workability evaluation> When the above test specimens were prepared, the coating workability (roller workability) of the second coating material was evaluated. The results are shown in Table 2. The evaluation criteria are as follows: A: The coating material did not stick to the rollers, allowing them to roll efficiently and smoothly. B: The coating material did not stick to the roller and it was possible to roll it. C: The coating material was slightly stuck to the roller, making it difficult to roll. D: The coating material was stuck to the roller and could not be rolled.

[0099] <Water resistance evaluation> The above test specimens were immersed in water at 20° C. for 48 hours, then removed and dried (23° C., 3 hours), and the condition of the coating was visually observed and evaluated for swelling, peeling, etc. The evaluation criteria were a six-level scale (AA>A>AB>B>C>D), with "A" being almost no abnormality and "D" being abnormality. The results are shown in Table 2.

[0100] [Table 2]

Claims

[Claim 1] A method for forming a coating comprising applying a first coating material to a substrate and then applying a second coating material to the substrate, the method comprising the steps of: the first coating material contains an epoxy resin emulsion (A), an amino group-containing resin (B), and an aqueous resin (C) (excluding (A) and (B)); a mixing weight ratio (solid content) of the epoxy resin emulsion (A) to the aqueous resin (C) is (A) / (C)<1; the second coating material contains an aqueous resin (D) having one or more functional groups selected from a carboxyl group, an epoxy group, and an isocyanate group; and the second coating material is applied with at least one applicator selected from a brush and a roller.

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