JP6946141B2 - Aqueous coating material - Google Patents

Description

The present invention relates to a novel water-based coating material.

In painting the interior and exterior walls and floors of buildings, various undercoat materials are selected and used in consideration of adhesion to the base material. Conventionally, such undercoat materials have mainly been solvent-based, but recently, water-based undercoat materials are being adopted in consideration of the environment, safety, and the like. For example, Patent Document 1 describes an aqueous primer containing a self-emulsifying cationic aqueous dispersion having a hydroxyl group and an amino group and an epoxy group-containing organosilane.

However, the water-based undercoat material may be inferior in adhesion to the solvent-based undercoat material. In particular, in recent years, in exterior building materials used for exterior wall surfaces, various coating films having functionality such as high weather resistance and stain resistance are provided. In the repair of such a coating film, it may be difficult to obtain sufficient adhesion with a water-based undercoat material, and the current situation is that solvent-based undercoat materials are often used.

JP-A-2002-256221

The present invention has been made in view of such problems, and an object of the present invention is to obtain an aqueous coating material capable of ensuring sufficient adhesion to various base materials and coating films. ..

As a result of diligent studies on such problems, the present inventors have determined the epoxy group-containing water-dispersible resin (A), the glycidyl group-containing silane compound (B), and the amino group-containing silane compound (C) in a specific weight ratio. The water-based coating material contained in the above was found, and the present invention was completed.

That is, the present invention has the following features.
1. 1. Contains an epoxy group-containing water-dispersible resin (A), a glycidyl group-containing silane compound (B), and an amino group-containing silane compound (C).
1 to 25 parts by weight of the glycidyl group-containing silane compound (B) and 1 to 75 parts by weight of the amino group-containing silane compound (C) with respect to 100 parts by weight of the resin solid content of the epoxy group-containing water-dispersible resin (A). part only contains,
An aqueous coating material in which the weight ratio of the contents of the glycidyl group-containing silane compound (B) and the amino group-containing silane compound (C) is (C) / (B)> 1.
A water-based coating material characterized in that the drying temperature in coating the water-based coating material is −5 ° C. or higher and 40 ° C. or lower .
2. The total amount of the glycidyl group-containing silane compound (B) and the amino group-containing silane compound (C) is 5 to 100 parts by weight with respect to 100 parts by weight of the resin solid content of the epoxy group-containing water-dispersible resin (A). It is characterized by being 1. Aqueous coating material according to .
3. 3. It is characterized by comprising a main agent containing the epoxy group-containing water-dispersible resin (A) and the glycidyl group-containing silane compound (B), and a curing agent containing the amino group-containing silane compound (C). Or 2. Aqueous coating material according to.
4. 1. It is an undercoat material applied to a siding board provided with an existing coating film. ~ 3. The water-based coating material according to any one of.
5. The coating amount is 0.05 to 0.5 kg / m ² . ~ 4. The water-based coating material according to any one of.

The water-based coating material of the present invention exhibits excellent adhesion to various substrates and coating films.

The aqueous coating material of the present invention contains an epoxy group-containing water-dispersible resin (A), a glycidyl group-containing silane compound (B), and an amino group-containing silane compound (C).

The epoxy group-containing water-dispersible resin (A) of the present invention (hereinafter, also simply referred to as “component (A)”) can be used without particular limitation as long as it contains an epoxy group. for example,
(A1) A product obtained by emulsion polymerization of a group of monomers containing an epoxy group-containing monomer.
(A2) Epoxy resin dispersed in water,
Etc., and these can be mixed and used.

The component (A1) is selected from, for example, an epoxy group-containing monomer, a (meth) acrylic acid alkyl ester and / or an aromatic monomer, and a nitrile group-containing monomer, an amide group-containing monomer, and a carbonyl group-containing monomer. Examples thereof include those in which a polymer of a monomer group containing more than one kind of polar monomer is used as a resin component.

Examples of the epoxy group-containing monomer include glycidyl (meth) acrylate, diglycidyl fumarate, 3,4-epoxycyclohexyl (meth) acrylate, 3,4-epoxyvinylcyclohexane, allylglycidyl ether, and ε-caprolactone-modified glycidyl (meth). ) Acrylate, β-methylglycidyl (meth) acrylate and the like can be mentioned. These can be used alone or in combination of two or more.
The weight ratio of the epoxy group-containing monomer in the monomer group is preferably 1 to 25% by weight (more preferably 3 to 20% by weight). Within such a range, a film having excellent adhesion can be formed. In the present invention, "a to b" are synonymous with "a or more and b or less".

The (meth) acrylic acid alkyl ester and / or aromatic monomer is the main component of the resin skeleton. In the present invention, the acrylic acid alkyl ester and the methacrylic acid alkyl ester are collectively referred to as (meth) acrylic acid alkyl ester. Further, the monomer is a general term for compounds having a polymerizable unsaturated double bond.

Specific examples of the (meth) acrylic acid alkyl ester include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, and n-amyl (. Meta) acrylate, isoamyl (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 and the like can be mentioned. These can be used alone or in combination of two or more.
The aromatic monomer is a compound having a polymerizable unsaturated double bond with an aromatic ring, and specific examples thereof include styrene, 2-methylstyrene, vinyltoluene, t-butylstyrene, chlorostyrene, vinylanisole, and vinyl. Examples thereof include naphthalene, divinylbenzene, phenyl (meth) acrylate, and benzyl (meth) acrylate. These can be used alone or in combination of two or more.

The weight ratio of the (meth) acrylic acid alkyl ester and / or aromatic monomer in the monomer group is preferably 60 to 99% by weight (more preferably 70 to 97% by weight). Within such a range, it is suitable in terms of adhesion and the like. Further, in the present invention, by using both such a (meth) acrylic acid alkyl ester and an aromatic monomer, performance such as adhesion can be further improved.

As the polar monomer, one or more selected from a nitrile group-containing monomer, an amide group-containing monomer, and a carbonyl group-containing monomer are used.
Among these, examples of the nitrile group-containing monomer include (meth) acrylonitrile, vinylidene cyanide, α-cyanoethyl (meth) acrylate and the like.
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), and N-. [3- (Dimethylamino) propyl] (meth) acrylamide, vinyl amide and the like can be mentioned.
Examples of the carbonyl group-containing monomer include acrolein, diacetone (meth) acrylamide, vinyl methyl ketone, vinyl ethyl ketone, vinyl butyl ketone and the like.

The weight ratio of the polar monomer in the monomer group is preferably 0.1 to 15% by weight, preferably 0.2 to 10% by weight. Within such a range, it is suitable in terms of storage stability, adhesion and the like.
In the present invention, an embodiment containing at least a nitrile group-containing monomer as the polar monomer is particularly preferable.

Further, other monomers copolymerizable with the above components can be used as long as the effects of the present invention are not impaired. Examples of such monomers include carboxyl group-containing monomers such as (meth) acrylic acid, crotonic acid, maleic acid, itaconic acid, fumaric acid, isocrotonic acid, and salicylic acid; aminomethyl acrylate, aminoethyl acrylate, and aminopropyl (meth). ) Acrylate, amino-n-butyl (meth) acrylate, butylvinylbenzylamine, vinylphenylamine, p-aminostyrene, N-methylaminoethyl (meth) acrylate, N-t-butylaminoethyl (meth) acrylate, etc. Amino group-containing monomer; hydroxyl group-containing monomer such as hydroxypropyl (meth) acrylate, ethylene glycol mono (meth) acrylate, glycerol mono (meth) acrylate; halogenated vinylidene-based monomer such as vinylidene fluoride; ethylene, propylene, isoprene, butadiene , Vinyl ether, vinyl ketone, silicone macromer and the like.

Among the above other monomers, it is desirable that the weight ratio of the carboxyl group-containing monomer in the monomer group is 3% by weight or less (preferably 1% by weight or less). An embodiment that does not contain a carboxyl group-containing monomer is also preferable. As for the amino group-containing monomer, it is desirable that the weight ratio in the monomer group is 3% by weight or less (preferably 1% by weight or less), and an embodiment containing no amino group-containing monomer is also preferable. In the present invention, by suppressing the use of such a monomer, the polarity of the epoxy group-containing monomer can be utilized and excellent adhesion can be exhibited.

The component (A1) can be produced by emulsion polymerization of a group of monomers in which the above-mentioned monomers are appropriately mixed. As the polymerization method, a known method may be adopted, and in addition to ordinary emulsion polymerization, soap-free emulsion polymerization, feed emulsion polymerization, seed emulsion polymerization and the like can also be adopted. At the time of polymerization, emulsifiers, initiators, dispersants, polymerization inhibitors, polymerization inhibitors, buffers, chain transfer agents and the like can be used.

As the emulsifier, various surfactants that can be used for emulsion polymerization can be used, and these may be reactive types (reactive surfactants) having a polymerizable unsaturated double bond. As the emulsifier, an anionic surfactant and a nonionic surfactant may be used alone or in combination, respectively.
Examples of the anionic surfactant include alkali metal sulfonic acid salts such as sodium dodecylbenzene sulfonate, sodium laurylnaphthalene sulfonate, and sodium stearyldiphenyl ether disulfonate; sodium lauryl sulfate, sodium polyoxyethylene lauryl ether sulfate, and polyoxyethylene. Examples thereof include sulfate ester alkali metal salts such as octylphenyl ether sodium sulfate.
Examples of the nonionic surfactant include polyoxyethylene lauryl ether, polyoxyethylene oleyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene nonylphenyl ether, oxyethylene / oxypropylene block copolymer and the like.

The average particle size of the component (A1) is preferably 300 nm or less (more preferably 20 to 120 nm, still more preferably 30 to 100 nm). When the average particle size is within such a range, advantageous effects such as impregnation reinforcing property, sealing property, and whitening resistance can be obtained. The average particle size referred to here is a value measured by a dynamic light scattering method.

Further, the glass transition temperature of the component (A1) can be adjusted by selecting the type of the monomer, the mixing ratio, and the like. The glass transition temperature may be appropriately set in consideration of the final required performance and the like, but is preferably about −50 to 80 ° C. (more preferably about -40 to 60 ° C.). The glass transition temperature can be obtained by the Fox calculation formula.

Examples of the component (A2) include those in which an epoxy resin liquid at room temperature is dispersed in an aqueous medium. Examples of such an epoxy resin include bisphenol type epoxy resins such as bisphenol A type epoxy resin and bisphenol F type epoxy resin.

The glycidyl group-containing silane compound (B) (hereinafter, also simply referred to as “component (B)”) of the present invention includes a compound having a glycidyl group (epoxide 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.

Examples of the compound having a glycidyl group (epoxide group) and an alkoxysilyl group include a glycidyl group-containing silane coupling agent, a hydrolyzed oligomer thereof, and a polymer having two or more alkoxysilyl groups and two or more glycidyl groups. Be done. Specifically, examples of the glycidyl group-containing silane coupling agent include glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, β-glycidoxyethyltrimethoxysilane, and β-glycidoxyethyltriethoxy. Silane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, γ-glycidoxypropyldimethyl Methoxysilane, γ-glycidoxypropyl (ethyl) dimethoxysilane, β-3,4-epoxycyclohexylethyltrimethoxysilane, β-3,4-epylcyclohexylethyltriethoxysilane,
Examples thereof include 8-glycidoxyoctyltrimethoxysilane, 8-glycidoxyoctylmethyldimethoxysilane, and 8-glycidoxyoctylmethyldiethoxysilane.

The hydrolyzed oligomer of the glycidyl group-containing silane coupling agent has an alkoxysilyl group and a glycidyl group, preferably having an alkoxy group amount of 10 to 80 wt% (more preferably 20 to 75 wt%) and an epoxy equivalent. Examples thereof include those having a weight of 200 to 950 g / mol (more preferably 300 to 900 g / mol). As such a component (B), a component having two or more kinds of alkoxysilyl groups, or a component in which a part or all of the alkoxysilyl groups is in the state of a silanol group can also be used.

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 100 to 500 g / mol (more preferably 150 to 400 g / mol). Can be mentioned.

In particular, in the present invention, the glycidyl group-containing silane coupling agent includes glycidoxymethyltrimethoxysilane, glycidoxymethyltriethoxysilane, β-glycidoxyethyltrimethoxysilane, and β-glycidoxyethyltriethoxy. Selected from silane, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, β-3,4-epoxycyclohexylethyltrimethoxysilane, β-3,4-epoxycyclohexylethyltriethoxysilane One or more are preferable, and an embodiment containing β-3,4-epoxycyclohexylethyltrimethoxysilane and β-3,4-epoxycyclohexylethyltriethoxysilane is more preferable. Further, it is more preferable that the hydrolyzed oligomer of the glycidyl group-containing silane coupling agent contains at least one epoxy equivalent of 300 to 950 g / mol (more preferably 500 to 900 g / mol). When these are used, the adhesion to the substrate and the adhesion to the substrate are further improved. Furthermore, the stability and pot life of the water-based coating material can be improved.

The aqueous coating material of the present invention contains the component (B) in an amount of 1 to 25 parts by weight (preferably 2 to 20 parts by weight) with respect to the resin solid content of the component (A). In this case, the effect of the present invention can be sufficiently obtained.

As the amino group-containing silane compound (C) of the present invention (hereinafter, also simply referred to as “component (C)”), a compound having an amino group and an alkoxysilyl group, a compound having an amino group and a cyclic siloxane, or the like is used. can. These can be used alone or in combination of two or more.

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 two or more alkoxysilyl groups and two or more amino groups. Specifically, as the amino group-containing silane coupling agent, for example,
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-anilinopropyltri Methoxysilane, γ-ureidopropyltrimethoxysilane, N-phenyl-γ-aminopropyltrimethoxysilane, N-vinylbenzyl-γ-aminopropyltriethoxysilane, N-β (aminoethyl) -8-aminooctylrimethoxy Examples thereof include silane, γ-triethoxysilyl-N- (1,3-dimethyl-butylidene) proviramine and the like.

As the hydrolyzed oligomer of the amino group-containing silane coupling agent, one having an alkoxysilyl group and an amino group can be used.
As such a component (C), a component in which a part or all of the alkoxysilyl group is in the state of a silanol group can also be used.

In particular, in the present invention, as the component (C), for example, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, N-β (aminoethyl) -γ-aminopropylmethyldimethoxysilane, N-β ( One or more selected from aminoethyl) -γ-aminopropylmethyldiethoxysilane is suitable. When these are used, the adhesion to the substrate is improved.

The aqueous coating material of the present invention contains the component (C) in an amount of 1 to 75 parts by weight (preferably 2 to 60 parts by weight, more preferably 4 to 50 parts by weight) with respect to the resin solid content of the component (A). do. In this case, the effect of the present invention can be sufficiently obtained.

Further, in the aqueous coating material of the present invention, the weight ratio of the content of the component (B) to the content of the component (C) is (C) / (B)> 1 (more preferably (C) / (B) = 2 to 8) is preferable. With such a ratio, a sufficient effect can be obtained in adhesion, and stability and pot life of the water-based coating material can be ensured.

The total amount of the component (B) and the component (C) is preferably 5 to 100 parts by weight (more preferably 10 to 75 parts by weight) with respect to 100 parts by weight of the resin solid content of the component (A). be. In such a range, the stability of the water-based coating material and the pot life can be ensured, and sufficient adhesion can be obtained.

The aqueous coating material of the present invention may be either a one-component type or a two-component type as long as it contains the above-mentioned component (A), the above-mentioned (B) component, and the above-mentioned (C) component. Then, it is preferable to prepare a two-component water-based coating material composed of a main agent containing the above-mentioned component (A) and the above-mentioned component (B) and a curing agent containing the above-mentioned component (C). As a result, the stability of the water-based coating material can be ensured, and the adhesion can be further improved.

In the case of a two-component water-based coating material, a polyamine or the like can be added to the curing agent.
Examples of the polyamine (D) include aliphatic polyamines, alicyclic polyamines, aromatic polyamines, heterocyclic amines, aliphatic polyamides, alicyclic polyamides, aromatic polyamides, aliphatic polyamide amines, and alicyclic polyamide amines. Examples include aromatic polyamide amines.

In addition to the above-mentioned components, the water-based coating material of the present invention includes coloring pigments, extender pigments, rust preventive pigments, pH adjusters, plasticizers, preservatives, fungicides, algae repellents, defoamers, as required. A leveling agent, a pigment dispersant, an anti-settling agent, an anti-dripping agent, a matting agent, a catalyst, a curing accelerator, and the like can be mixed within a range in which the effects of the present invention are not impaired. The pH of the aqueous coating material of the present invention is preferably 3 to 12 (more preferably 4 to 11). Further, the stability, adhesion and the like of the aqueous coating material can be further improved by adjusting the pH to alkaline (preferably pH 8.5 or higher) with a pH adjusting agent. When the aqueous coating material of the present invention is of the above two-component type, it is preferable that the pH of the main agent satisfies the above.

The water-based coating material of the present invention is suitably used as an undercoat material for coating interior / exterior wall surfaces, floor surfaces, and the like. For example, base materials such as mortar, concrete, ceramic siding board, ceramic siding board, metal siding board, extruded board, slate board, calcium silicate board, ALC board, metal, wood, glass, ceramics, synthetic resin, etc. Alternatively, it is suitably used as an undercoat material to be applied to a base material such as a wide variety of existing coating films formed on such a base material (surface of the base material). In addition, the shape of such a base (base material or existing coating film) is smooth (flat), various uneven patterns (stone tone, brick / tile tone, wood grain tone, border tone, plaster wall tone, spraying). Those having a key) and the like can be mentioned. Furthermore, it can also be applied to a base including a sealing joint portion.

In particular, the water-based coating material of the present invention is suitable as an undercoat material for repairing a base, and can be suitably applied, for example, as an undercoat material for repairing a siding board provided with an existing coating film.

The existing coating film is various coating films that have already been coated on the above-mentioned base material by on-site coating, factory coating (line coating), or the like. For example, an organic coating film, an inorganic coating film, or an organic-inorganic composite coating film. And at least one kind of coating film selected from the above. Examples of the existing coating film include colored coating films (enamel-based coating films, printing coating films, etc.), clear coating films, and laminated coating films thereof, and various coating materials are applied and cured on the base material. It is a formed coating film. Such a coating material may be any of a room temperature drying type, a room temperature curing type, a baking curing type, an ultraviolet (UV) curing type, an electron beam curing type and the like.

Examples of the binder of such a coating material include organic binders such as acrylic resin, polyurethane resin, epoxy resin, fluororesin, alkyd resin, and polyester resin, silicon resin, alkoxysilane, colloidal silica, and silicate. Examples thereof include an inorganic binder, an organic-inorganic composite binder such as an acrylic silicone resin, and the like.

The present invention is particularly suitable when the existing coating film is an inorganic coating film (including the above-mentioned inorganic binder), an organic-inorganic composite coating film, a fluororesin coating film, or the like, and further, for these clear coating films. It can be suitably applied. Such an existing coating film may contain a photocatalytic titanium oxide.

Specific coating materials include, for example, a weather-resistant topcoat paint for construction (JIS K5658: 2010), a weather-resistant paint for steel structures (JIS K5659: 2008), and a glossy synthetic resin emulsion paint (JIS K5660: 2008). Fireproof paint for construction (JIS K5661: 1970), synthetic resin emulsion paint (JIS K5663: 2008), road surface marking paint (JIS K5665: 2011), multicolored pattern paint (JIS K5667: 2003), synthetic resin emulsion pattern paint (JIS) K5668: 2010), acrylic resin-based non-aqueous dispersion paint (JIS K5670: 2008), lead / chrome-free rust preventive paint (JIS K5674: 2008), high solar reflectance paint for roofs (JIS K5675: 2011), for buildings Examples thereof include floor paints (JIS K5970: 2008), building coating waterproofing materials (JIS A6021: 2011), building finishing coatings (JIS A6909: 2014), and the like.

In coating the water-based coating material, for example, various methods such as brush coating, roller coating, and spray coating can be adopted. In addition to the above, when painting in a factory, a roll coater, a flow coater, or the like can be used for painting.

The amount of the water-based coating material applied is preferably about 0.05 to 0.5 kg / m ² (more preferably 0.07 to 0.3 kg / m ² ). The number of times the water-based coating material is applied may be appropriately set depending on the condition of the base, but is preferably 1 to 2 times. The drying time of the aqueous coating material is preferably 1 hour or more and 1 week or less. The drying temperature is preferably −10 ° C. or higher and 50 ° C. or lower, and more preferably −5 ° C. or higher and 40 ° C. or lower.

The coating film formed by the water-based coating material of the present invention has excellent adhesion to a wide variety of topcoat materials. The topcoat material is not particularly limited as long as it is generally used for painting a building.

The coating method of the topcoat material is not particularly limited and can be coated by a known method, but for example, it can be coated by various methods such as brush coating, spray coating, roller coating, roll coater, and flow coater. That is, each topcoat material may be coated based on a normal process with the optimum coating specifications for each topcoat material.

Examples and comparative examples are shown below to further clarify the features of the present invention.

(Manufacturing of water-based coating materials 1 to 15)
According to the formulation shown in Table 1, the component (A), the component (B), and the additive were mixed by a conventional method to prepare a main agent. Further, the component (C) was used as a curing agent. The pH of each main agent was pH = 10 for the coating materials 1 to 2, 4 to 9, and 13 to 15, and pH = 6 for the coating materials 3 and 10 to 12.
The following raw materials were used.
(A1) Epoxy group-containing synthetic resin emulsion [styrene / 2-ethylhexyl acrylate / glycidyl methacrylate / acrylonitrile (weight ratio) = 55/28/14/3, solid content: 40% by weight, average particle size: 83 nm]
(B-1) γ-glycidoxypropyltrimethoxysilane ・ (B-2) γ-glycidoxypropylmethyldimethoxysilane ・ (B-3) β-3,4-epoxycyclohexylethyltrimethoxysilane ・ ( B-4) Hydrolyzed oligomer of glycidyl group-containing silane coupling agent [alkoxy group (methoxy group and ethoxy group) amount 50 wt%, epoxy equivalent 830 g / mol]
(B-5) Hydrolyzed oligomer of glycidyl group-containing silane coupling agent [alkoxy group (methoxy group) amount 17 wt%, epoxy equivalent 280 g / mol]
・ (C-1) N-β (aminoethyl) -γ-aminopropyltrimethoxysilane ・ (C-2) N-β (aminoethyl) -γ-aminopropylmethyldimethoxysilane ・ Additive 1: Ammonia water ・Additive 2: Antifoaming agent, thickener, film-forming aid, etc.

(Preparation of test specimen)
On a siding board on which an inorganic clear coating film is formed as an existing coating film, an aqueous coating material obtained by mixing a main agent and a curing agent is applied immediately after mixing so that the coating ^{amount is 0.1 kg / m 2.} Then, it is dried under standard conditions (temperature 23 ° C., relative humidity 50%) for 4 hours, and then a water-based topcoat material (acrylic silicon emulsion paint) is applied so that the coating ^{amount is 0.1 kg / m 2.} Under standard conditions, a test body [I] dried for 1 day, a test body [II] dried for 4 days, and a test body [III] dried for 7 days were prepared.

(Examples 1 to 12, Comparative Examples 1 to 3)
The following evaluations were carried out for each of the prepared test specimens [I], [II], and [III]. The results are shown in Table 1.
<Adhesion evaluation>
The prepared test piece was evaluated for adhesion by a grid tape method according to JIS K 5600-5-6. The evaluation criteria are as follows.
A: Defect area is within 5% B: Defect area is 5 to 25%
C: Defect area is 25 to 50%
D: Defect area is 50% or more

<Available time>
After mixing the main agent and the curing agent, the time until the fluidity was lost was measured. The evaluation criteria are as follows.
AA: 360 minutes or more A: 240 minutes or more and less than 360 minutes B: 120 minutes or more and less than 240 minutes C: 30 minutes or more and less than 120 minutes D: less than 30 minutes

Claims (5)

Contains an epoxy group-containing water-dispersible resin (A), a glycidyl group-containing silane compound (B), and an amino group-containing silane compound (C).
1 to 25 parts by weight of the glycidyl group-containing silane compound (B) and 1 to 75 parts by weight of the amino group-containing silane compound (C) with respect to 100 parts by weight of the resin solid content of the epoxy group-containing water-dispersible resin (A). part only contains,
An aqueous coating material in which the weight ratio of the contents of the glycidyl group-containing silane compound (B) and the amino group-containing silane compound (C) is (C) / (B)> 1.
A water-based coating material characterized in that the drying temperature in coating the water-based coating material is −5 ° C. or higher and 40 ° C. or lower . The total amount of the glycidyl group-containing silane compound (B) and the amino group-containing silane compound (C) is 5 to 100 parts by weight with respect to 100 parts by weight of the resin solid content of the epoxy group-containing water-dispersible resin (A). The water-based coating material according to claim 1, wherein the aqueous coating material is provided . 1. The water-based coating material according to claim 2. The water-based coating material according to any one of claims 1 to 3, wherein the undercoat material is applied to a siding board provided with an existing coating film. The amount of application is 0.05 to 0.5 kg / m ² The water-based coating material according to any one of claims 1 to 4.