JPH11197592A - Metallic finishing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a metallic finishing method especially by an aqueous metallic paint by which the crazing of a thermosetting aqueous paint applied on a thermosetting paint is most effectively prevented without adversely affecting the performances such as the finished appearance of the coating film, interlayer adhesion and resistance to water, solvent and chemicals. SOLUTION: A material to be coated is coated with the org. solvent-type or nonaqueous dispersion-type thermosetting paint A, a thermosetting aqueous metallic paint B is applied on the paint A, further a transparent thermosetting paint C is applied, and then the coating film consisting of the three layer is heated and simultaneously cured.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metallic finishing method, and more particularly to a metallic finishing method using an aqueous metallic paint.

[0002]

2. Description of the Related Art An organic solution type or non-aqueous dispersion type thermosetting paint containing a neutralized polyvalent carboxylic acid resin having an acid value of 5 to 100 and an amino resin as essential components and containing no metallic pigment. The viscosity of the applied coating material is adjusted to 10 poise (20 ° C.) or more, a thermosetting aqueous metallic coating material is applied thereon, and a transparent thermosetting coating material is applied. A metallic finishing method characterized by heating and simultaneously curing the three-layer coating film is known from Japanese Patent Publication No. 4-25076.

[0003] However, the method disclosed in this publication prevents cracks from being generated in a coating film of a thermosetting aqueous metallic paint further applied on an organic solution type or non-aqueous dispersion type thermosetting paint containing no metallic pigment. There was a problem that it was not possible.

[0004]

DISCLOSURE OF THE INVENTION The present inventors have solved the above-mentioned problems, and have developed a thermosetting type which is further coated on an organic solution type or non-aqueous dispersion type thermosetting paint containing no metallic pigment. As a result of intensive research to develop a metallic finishing method with improved resistance to cracking of the coating film of the aqueous metallic paint, it contains specific crosslinked fine particles, organic solution type without metallic pigment or non-aqueous dispersion type It has been found that when a thermosetting aqueous metallic paint is applied over the thermosetting paint, it is extremely effective in solving the above problem. That is, the organic solution type or non-aqueous dispersion type thermosetting paint containing no metallic pigment containing specific crosslinked fine particles has a coating film finish appearance, interlayer adhesion, water resistance, solvent resistance, chemical resistance and the like. The present inventors have found that the present invention is extremely effective in preventing cracks in a thermosetting aqueous metallic paint applied repeatedly without adversely affecting various performances, and completed the present invention.

[0005]

Thus, according to the present invention, an organic solution-type or non-aqueous dispersion type thermosetting coating material (A) containing no metallic pigment is applied to an object to be coated, and the applied coating material ( A) A thermosetting aqueous metallic paint (B) is applied on top of A), and a transparent thermosetting paint (C) is applied, and then the three-layer coating is heated and cured simultaneously. Wherein the paint (A) comprises (a) a film-forming binder resin, (b) a volatile organic liquid diluent in which the film-forming binder (a) is dissolved, and (c) a diluent. (B) contains polymer fine particles that are stably dispersed without being dissolved in the solution of the binder resin (a), and the polymer fine particles (c) are
(I) a polymerizable monomer having at least two radically polymerizable unsaturated groups in a molecule, (ii) a (meth) acrylate having a saturated cyclic group, and (iii) other radically polymerizable unsaturated monomers. The present invention provides a metallic finishing method characterized by being gelled polymer fine particles obtained by emulsion polymerization in the presence of a reactive emulsifier containing an allyl group.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The paints used in the present invention and the method for finishing a metallic coating film using these paints will be specifically described below.

Thermosetting paint (A): This paint makes the metallic pigment in the subsequently formed aqueous metallic coating uniformly oriented parallel to the coating surface without being affected by the atmospheric humidity, and the metallic paint This is an organic solution type or non-aqueous dispersion type thermosetting paint which is used for finishing a coated surface smoothly and does not contain a flaky metallic pigment.

In the present invention, the film-forming binder resin (a) used in the thermosetting paint (A) has an acid value of 5 to 5.
It is a mixture of a neutralized product of a polycarboxylic acid resin having 100 mgKOH / g and an amino resin.

As the polyvalent carboxylic acid resin having an acid value of 5 to 100 mgKOH / g, various known resins can be used as long as the above requirements are satisfied. Acid, methacrylic acid, maleic acid, itaconic acid, crotonic acid and the like, at least one kind of carboxyl group-containing polymerizable unsaturated monomer, for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, hydroxypropyl acrylate, Hydroxyalkyl esters of acrylic acid or methacrylic acid having 1 to 8 carbon atoms such as hydroxypropyl methacrylate; methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl Acrylate, isobutyl methacrylate, t- butyl acrylate, t- butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 2-ethylhexyl acrylate, 2-
Acrylic acid or methacrylic acid such as ethylhexyl methacrylate, lauryl acrylate, lauryl methacrylate, stearyl acrylate, stearyl methacrylate, decyl acrylate, etc. has 1 to 2 carbon atoms.
4 alkyl or cycloalkyl esters; functional groups such as acrylamide, methacrylamide, N-methylacrylamide, N-ethylmethacrylamide, diacetoneacrylamide, N-methylolacrylamide, N-methylolmethacrylamide, N-butoxymethylacrylamide Amide or methacrylamide; polymerizable nitrile such as (meth) acrylonitrile; glycidyl group-containing vinyl monomer such as glycidyl acrylate, glycidyl methacrylamide, allyl glycidyl ether; styrene, vinyl toluene, vinyl propionate;
α-methylstyrene, vinyl acetate, acrylonitrile,
Vinyl monomers such as methacrylonitrile, vinyl propionate, vinyl pivalate, and verova monomer (shell chemical products); α-olefins such as ethylene and propylene; diene compounds such as butadiene and isoprene; vinyl trimethoxysilane and vinyltriethoxysilane Copolymerized with other radically polymerizable unsaturated monomers such as monomers containing a hydrolyzable alkoxysilyl group such as vinyltris (2-methoxyethoxy) silane, .gamma.-methacryloxypropyltrimethoxysilane and vinyltriacetooxysilane. Acrylic resin or vinyl resin, preferably having a number average molecular weight of about 5,000 to about 40,000, obtained at least; ethylene glycol, diethylene glycol, propylene glycol, butanediol, pentanediol, 2,2 Polyhydric alcohols such as dimethylpropanediol, glycerin, trimethylolpropane, and pentaerythritol, and monohydric alcohols used in combination, if necessary, or monoepoxy compounds having one glycidyl group in the molecule (for example, "Cardura E" (products Name, manufactured by Shell Chemical Co., Ltd.) as an alcohol component, and phthalic anhydride, isophthalic acid, terephthalic acid tetrahydrophthalic anhydride, hexahydrophthalic anhydride, maleic anhydride, succinic anhydride, adipic acid, sebacic acid, trimellitic anhydride An acid, a polybasic acid such as pyromellitic anhydride, and a monobasic acid such as benzoic acid or t-butylbenzoic acid used in combination as needed as an acid component, and condensing the alcohol component and the acid component. Oil-free alkyd resin or the above alcohol component and In addition to the above acid components, an oil component which is a castor oil, a dehydrated castor oil, a tung oil, a safflower oil, a soybean oil, a linseed oil, a tall oil, a coconut oil, etc., and a mixture of one or more of these fatty acids Is an oil-modified alkyd resin obtained by adding an acid component and an alcohol component to each other and reacting the three components, and having a number average molecular weight of preferably 500 to 10,000; A graft copolymer grafted to a resin, preferably having a number average molecular weight of about 5,000 to about 40,000, for example, a vinyl monomer and / or an acrylic monomer on an alkyd resin having a copolymerizable unsaturated group; And a graft copolymer obtained by reacting the same.

The acid value of the above polycarboxylic acid resin is 5-1.
It must be within the range of 00 mg KOH / g, preferably within the range of 10 to 50 mg KOH / g, and more preferably within the range of 30 to 50 mg KOH / g. When the acid value of the resin is less than 5 mgKOH / g, the thermosetting water-based metallic paint (B) to be subsequently applied has poor adaptability, and the water-based metallic paint (B) has no effect of absorbing moisture. Defects such as uneven flow of the metallic paint (B) and sagging are caused, and the metallic feeling is significantly deteriorated. Conversely, when the acid value is more than 100 mgKOH / g, the water resistance of the coating film is deteriorated, which is not preferable.

The above-mentioned polycarboxylic acid resin can be made to contain a hydroxyl group by copolymerizing the above-mentioned hydroxyalkyl ester, and the use of such a resin improves the coating film hardness, water resistance and acid resistance. I do. In this case, the hydroxyl value of the resin is about 10 to about 200 mg KO.
In the range of H / g, a remarkable effect of improving the coating film performance is recognized, and particularly, the range of 25 to 70 mgKOH / g is preferable.

Examples of the basic substance that neutralizes these polyvalent carboxylic acid resins include ammonia, methylamine, and the like.
Various basic substances such as ethylamine, dimethylamine, diethylamine, trimethylamine, triethylamine, dimethylethanolamine, diethanolamine, and triethanolamine can be used. In general, the amount of the neutralizing agent used is preferably about 0.1 to about 2.0 equivalents, more preferably about 0.3 to about 1.2 equivalents, based on the carboxyl group in the resin. If the amount of the neutralizing agent is less than about 0.1 equivalent, the thermosetting aqueous metallic paint (B) to be subsequently applied has poor adaptability, and the aqueous metallic paint (B) has no effect of absorbing moisture. Therefore, defects such as uneven flow of the aqueous metallic paint (B) and sagging are caused, and the metallic feeling is remarkably deteriorated. Conversely, about 2.0
If the amount is more than the equivalent, the performance of the coating film deteriorates.

The amino resin used in the present invention is a cross-linking agent for curing the above polycarboxylic acid resin, and various known cross-linking agents are used. Examples thereof include melamine, benzoguanamine, triazine compounds, urea and dicyandiamide. And the like, obtained by condensation or co-condensation with formaldehyde, and modified with a denaturing agent. Among these, melamine formaldehyde resin is preferred.

The compounding ratio of the polycarboxylic acid resin to the amino resin is usually about 50 to about 90 parts by weight of the polycarboxylic acid resin based on the weight of the solid content, preferably the coating performance. From a viewpoint, about 65 to about 85 parts by weight, amino resin: about 10 to about 50 parts by weight, preferably about 15 to about 35 parts by weight.
Use within the range of parts by weight.

The diluent (b) used in the present invention is a volatile organic liquid diluent which dissolves the film-forming binder resin (a) but disperses the polymer fine particles (c) stably without dissolving. And any mixture of liquids conventionally used as solvents in coating compositions. Specifically, for example, aromatic hydrocarbons such as toluene and xylene; petroleum fractions of various boiling ranges containing a substantial proportion of aromatics; aliphatic hydrocarbons such as hexane, heptane, octane; butyl acetate; Ester solvents such as ethylene glycol diacetate and ethylene glycol 2-ethoxyethyl acetate; ether solvents such as diethyl ether, dipropyl ether, dibutyl ether, diethylene glycol monobutyl ether and propylene glycol monomethyl ether; methanol, ethanol, n-propanol, Examples thereof include alcohol solvents such as isopropanol, n-butanol, isobutanol, t-butanol and hexanol. Of these, ether solvents are preferred.

The polymer fine particles as the component (c) used in the present invention include (i) a polymerizable monomer having at least two radically polymerizable unsaturated groups in the molecule;
(i) a gelled polymer obtained by subjecting (meth) acrylate having a saturated cyclic group and (iii) other radically polymerizable unsaturated monomer to emulsion polymerization in the presence of a reactive emulsifier containing an allyl group in the molecule; Fine particles.

Examples of the monomer (i) include a polymerizable unsaturated monocarboxylic acid ester of a polyhydric alcohol, a polymerizable unsaturated alcohol ester of a polybasic acid, and an aromatic compound substituted with two or more vinyl groups. And specific examples thereof include ethylene glycol diacrylate, ethylene glycol diacrylate, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol dimethacrylate,
1,3-butylene glycol dimethacrylate, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, 1,4-butanediol diacrylate, neopentyl glycol diacrylate, 1,6-hexanediol acrylate, pentaerythritol diacrylate, penta Erythritol triacrylate, pentaerythritol tetraacrylate, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, glycerol dimethacrylate, glycerol diacrylate, glycerol allyloxydimethacrylate, 1,1,1-trishydroxymethylethanediacrylate , 1,1,1-trishydroxymethyl eta Triacrylate, 1,1,1
Trishydroxymethylethane trimethacrylate,
1,1,1-trishydroxymethylpropane diacrylate, 1,1,1-trishydroxymethylpropane triacrylate, 1,1,1-trishydroxymethylpropane dimethacrylate, 1,1,1-trishydroxymethylpropane triacrylate Examples include methacrylate, triallyl cyanurate, triallyl isocyanurate, triallyl trimellitate, diallyl terephthalate, diallyl phthalate and divinylbenzene.
These monomers (i) may be used alone or in combination of two or more.

(Meth) having a saturated cyclic group of the above (ii)
Acrylate plays an extremely important role in the polymer fine particles as the component (c). That is, when the polymer fine particles (c) contain a saturated cyclic group, the coating of the thermosetting aqueous metallic paint further applied on the paint (A) does not crack. It works. Examples of the (meth) acrylate having a saturated cyclic group include, for example, cyclohexyl acrylate, cyclohexyl methacrylate, tricyclodecane triacrylate, isobornyl acrylate, isobornyl methacrylate and the like. ,
Examples include isobornyl acrylate and isobornyl methacrylate. These monomers (ii) may be used alone or in combination of two or more.

The other radically polymerizable unsaturated monomer of the above (iii) is the remaining component constituting the polymer fine particles (c), and specific examples thereof include the carboxyl group exemplified in the film-forming binder resin (a). The group-containing polymerizable unsaturated monomer, acrylic acid or methacrylic acid, has 1 carbon atom.
~ 8 hydroxyalkyl esters, acrylic or methacrylic acid alkyl or cycloalkyl esters having 1 to 24 carbon atoms, functional acryl or methacrylamide, polymerizable nitrile, glycidyl group-containing vinyl monomer, vinyl Examples thereof include a monomer, a diene compound, and a hydrolyzable alkoxysilyl group-containing monomer. These monomers (iii) may be used alone or in combination of two or more depending on the desired properties.

The proportion of the monomers (i) to (iii) constituting the polymer fine particles (c) in the present invention is not strictly limited, but is generally 1 to 99% by weight, preferably monomer (i). 3 to 30
% By weight, more preferably 5 to 20% by weight monomer (ii): 1 to 99% by weight, preferably 3 to 5% by weight
0% by weight, more preferably 10 to 30% by weight monomer (iii): 0 to 98% by weight, preferably 20
To 94% by weight, more preferably 50 to 85% by weight.

The reactive emulsifier containing an allyl group in the molecule used for the emulsion polymerization of the monomers (i) to (iii) includes, for example, those belonging to the following groups.

I) Allyl group-containing anionic reactive emulsifier The following general formula or

[0023]

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In the formula, R ₁ represents hydrogen or a methyl group, R ₂ represents a hydrocarbon group or a hydrocarbon having a substituent or an organic group containing an oxyalkylene group, and A represents an alkylene having 2 to 4 carbon atoms. Represents a group or a substituted alkylene group, n is 0 or a positive number, M represents an alkali or alkaline earth metal, ammonium, an organic amine base, or an organic quaternary ammonium base, and m represents M A sulfonic acid salt represented by the following general formula or

[0025]

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In the formula, R ₁ represents a hydrocarbon group, a phenyl group, an amino group or a carboxylic acid residue which may have a substituent, R ₂ represents a hydrogen atom or a methyl group, and A has 2 carbon atoms. Represents 4 to 4 alkylene groups, and n represents 0 to 1
A positive cation of 00, M represents a monovalent or divalent cation, and m represents an ionic value of M, a sulfosuccinic acid diester salt represented by the following formula;

[0027]

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In the formula, R ₁ represents an alkyl, alkenyl or aralkyl group having 4 to 18 carbon atoms;
₂ represents hydrogen or an alkyl, alkenyl, or aralkyl group having 4 to 18 carbon atoms, and A represents 2 to 2 carbon atoms.
4 represents an alkylene group or a substituted alkylene group,
n is an integer of 2 to 200, M is an alkali metal atom,
And a compound represented by NH or an alkanolamine residue. These are known per se (for example, Japanese Patent Publication No. 49-46291, Japanese Patent Application Laid-Open No.
See JP-A-203960, JP-A-62-221431, JP-A-63-23725 and the like. ), "Eleminor JS-2" (trade name, manufactured by Sanyo Chemical Industries, Ltd.), "Latemul S" series (trade name, manufactured by Kao Corporation), "Aqualon HS" series (trade name, Daiichi Kogyo Seiyaku Co., Ltd.) Commercially available.

II) Cationic reactive emulsion containing allyl group
The following general formula

[0030]

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In the formula, R ₁ represents an optionally substituted hydrocarbon group having 8 to 22 carbon atoms, R ₂ and R ₃ represent an alkyl group having 1 to ₃ carbon atoms, and R ₄ represents hydrogen. atom or a methyl group,, X ^- can be mentioned reactive emulsifying agent having a monovalent represents an anion, in the quaternary ammonium salt represented. This is known per se (Japanese Unexamined Patent Publication No.
0-78947), for example, "Latemul K-1"
80 "(trade name, manufactured by Kao Corporation).

III) Allyl group-containing nonionic reactive milk
The following general formula

[0033]

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[0034] In the formula, R ₁ represents an alkyl group, alkenyl group or aralkyl group having 4 to 18 carbon atoms, R ₂
Represents hydrogen or an alkyl group, an alkenyl group or an aralkyl group having 4 to 18 carbon atoms, A represents an alkylene group or a substituted alkylene group having 2 to 4 carbon atoms, and n is an integer of 2 to 200. Compounds. This is known per se (Japanese Patent Application Laid-Open No. 62-10 / 1987).
No. 0502), for example, commercially available as “H-3355N” (trade name, manufactured by Daiichi Kogyo Seiyaku).

In the above emulsion polymerization, a reactive emulsifier containing an acrylic group, which is a relatively low reactive group,
Any of the above-mentioned anionic, cationic, and nonionic reactive emulsifiers can be widely used without being limited to those exemplified as the representative examples above, but the reaction gradually incorporated into the polymer during polymerization. Suitable emulsifiers are suitable, and in the present invention, cationic reactive emulsifiers are preferred.

Nonionic reactive emulsifier Anionic reactive emulsifier or cationic reactive emulsifier can be mixed and used in an arbitrary ratio, and the mixing ratio is appropriately selected according to desired characteristics.

The amount of the reactive emulsifier used can be either alone or as a mixture of a cationic reactive emulsifier and a nonionic reactive emulsifier or a mixture of an anionic reactive emulsifier and a nonionic reactive emulsifier. When using,
The total amount is generally in the range of 0.1 to 30 parts by weight, preferably 0.5 to 5 parts by weight, based on 100 parts by weight of the total of the monomers (i) to (iii) constituting the polymer fine particles (c). Is appropriate.

The polymerization initiator used in the above emulsion polymerization is represented by the following general formula:

[0039]

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In the formula, X represents a linear or branched alkylene group having 2 to 12 carbon atoms, or

[0041]

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In the formula, at least one of X ¹ , X ² and X ³ is a hydroxyl group, and the rest is hydrogen. These are known per se (Japanese Patent Application Laid-Open No. 61-218618,
JP-A-61-63643), for example, VA series (trade name, manufactured by Wako Pure Chemical Industries, Ltd.). The required amount of polymerization initiator to be used will be clear in the art. In general, the optimum required amount is 1 in total of the monomers (i) to (iii) forming the fine particle polymer (c).
It is in the range of 0.1 to 1.5 parts by weight with respect to 00 parts by weight.

The copolymerization of the monomers (i) to (iii) can be carried out by an emulsion polymerization method which is a known method for producing an acrylic copolymer. The above monomer mixture is prepared in an aqueous medium in the presence of a reactive emulsifier containing an allyl group and a water-soluble azoamide compound polymerization initiator at a reaction temperature of usually about 50 to 100 ° C, preferably 80 to 95 ° C. The reaction can be performed by continuing the reaction for 20 hours.

The aqueous dispersion of the polymer fine particles (c) obtained by emulsion polymerization is usually about 10 to 4 based on the total weight.
It has a resin solids content of 0% by weight. The particle size of the fine particle polymer (c) in the aqueous dispersion is generally 500 nm or less, preferably in the range of 50 to 100 nm. The particle size can be adjusted by adjusting the type and amount of the reactive emulsifier having an allyl group in the molecule, and a fine particle polymer (c) having a particle size in a desired range can be easily obtained. .

The mixing ratio of the diluent (b) to the binder resin (a) is such that the binder resin (a) can be uniformly dissolved, and the polymer fine particles (c) are mixed with the diluent (b) of the binder resin (a). b) The diluent (b) is usually used in the binder resin (a), although it is not particularly limited as long as it is a quantitative ratio that can be stably dispersed in the solution. ) It is desirable to use 200 to 600 parts by weight for 100 parts by weight. The mixing ratio of the polymer fine particles (c) to the binder resin (a) is generally in the range of 1 to 50 polymer fine particles (c) per 100 parts by weight of the binder resin (a).
It is desirably used within the range of 5 parts by weight, preferably 5 to 40 parts by weight, more preferably 5 to 30 parts by weight.

In the present invention, the polymer fine particles (c) are usually added and blended in a uniform system containing the binder resin (a) and the diluent (b). At this time, it is desirable that the polymer fine particles (c) be converted into a form dispersed in an organic solvent and then blended. The conversion from the aqueous dispersion of the polymer fine particles (c) to the organic solvent dispersion is carried out by evaporating water from the aqueous dispersion of the polymer fine particles (c) by a spray drying method, simple drying, or the like. By taking it out and then redispersing it in an organic solvent.

In the present invention, the non-metallic paint (A) can be applied directly to the object to be coated. However, a primer such as an electrodeposition paint (anionic or cationic) and a thermosetting intermediate paint are applied. However, it is preferable to apply the coating after curing these coatings. As the coating machine, it is preferable to use an atomization type coating machine, for example, an air spray coating machine, an airless spray coating machine and an air atomization type or a rotary electrostatic coating machine, and the like. About 15 to about 60 seconds with Ford Cup # 4,
It is particularly preferable to adjust the coating time to 15 to 35 seconds (20 ° C.).
μm, especially about 5 to about 15 μm, are suitable.

The viscosity of the applied non-metallic paint (A) can be easily adjusted by appropriately adjusting the nonvolatile content, solvent composition, viscosity and the like of the paint at the time of coating. When the viscosity is low, the viscosity can be adjusted by leaving at room temperature or preheating to evaporate the solvent and the like. In order to minimize the coating interval between the non-metallic paint (A) and the water-based metallic paint (B) described below, the non-metallic paint (A) should be coated so that the coating viscosity immediately after application becomes high. A viscosity modifier is added to (A), and various known viscosity modifiers can be used.
As specific examples, for example, “Benton 27” (manufactured by NL Chemical Company, thixotropic agent), “Erosil #
200 "(manufactured by Nippon Aerosil Co., Ltd., silica-based thixotropic agent).

Thermosetting aqueous metallic paint (B): The aqueous metallic paint (B) is an organic solution type or non-aqueous dispersion type thermosetting paint (A) containing no metallic pigment.
A paint to be applied on the coating film surface, with water as its main solvent, water-soluble or water-dispersed thermosetting acrylic resin,
The main component is a metallic pigment, and if necessary, a coloring pigment,
It comprises an extender, a coating surface adjuster, a viscosity adjuster and the like.

As the water-soluble or water-dispersible thermosetting acrylic resin which is a constituent component of the water-based metallic coating material (B), all of conventionally known ones are included. As typical examples, for example, water-soluble acrylic resins include α, β
An acid value obtained by polymerizing one or more monomers selected from monoethylenically unsaturated carboxylic acids, hydroxyalkyl esters thereof and other α, β-monoethylenically unsaturated monomers About 20 to about 100 and hydroxyl value about 2
0 to about 200 acrylic resins can be mentioned.

The polymerizable unsaturated monomer which is a raw material of the above water-soluble acrylic resin includes α, β-monoethylenically unsaturated carboxylic acids such as acrylic acid, methacrylic acid, maleic acid and itaconic acid, and (meth) Hydroxyalkyl esters of α, β-monoethylenically unsaturated carboxylic acids such as 2-hydroxyethyl acrylate, 2-hydroxypropyl (meth) acrylate and methyl (meth) acrylate;
Α, β such as ethyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, lauryl (meth) acrylate, and decyl (meth) acrylate Alkyl esters of monoethylenically unsaturated carboxylic acids; (meth) acrylamide derivatives such as (meth) acrylamide, N-methylol (meth) acrylamide and diacetone acrylamide; α, β-mono such as glycidyl (meth) acrylate Glycidyl esters of ethylenically unsaturated carboxylic acids; vinyl esters of saturated carboxylic acids such as vinyl acetate and vinyl propionate; and aromatic unsaturated monomers such as styrene, α-methylstyrene, and vinyl toluene.

The polymerization reaction is carried out using the above monomer in a water-compatible organic solvent such as butyl cellosolve using a radical polymerization catalyst such as azobisisobutyronitrile, benzoyl peroxide and dibutyl peroxide. If the acid value of the resin is less than about 20, it is difficult to dissolve in water, and if it exceeds about 100, the performance of the coating film is deteriorated due to the influence of residual carboxyl groups.

The water-soluble acrylic resin thus obtained is
Ammonia or triethylamine, monoethanolamine, diethanolamine, triethanolamine,
Neutralization is performed using a basic substance such as an amine such as dimethylaminoethanol or an alkali metal hydroxide such as sodium hydroxide or potassium hydroxide. Thereafter, water and, if necessary, an organic solvent compatible with water are added to obtain an appropriate solid content, followed by dilution with water.

On the other hand, the water-dispersible acrylic resin is described above by using an ionic or nonionic or both low-molecular or high-molecular surfactant as a dispersion stabilizer, or using a water-soluble resin. It is a known product prepared by emulsion polymerization of a polymerizable unsaturated monomer, which is a raw material of a water-soluble acrylic resin, in an aqueous medium by a generally known method.

Examples of the water-soluble amino resin used as a crosslinking agent for the acrylic resin include those obtained by condensation or co-condensation of melamine, benzoguanamine, a triazine compound, urea, dicyandiamide and the like with formaldehyde, Those modified with a denaturant of alcohols of 1 to 8 and carboxyl group-containing amino resins are also used. Usually, about 0.5 to about 2.0 equivalents of formaldehyde are reacted with one equivalent of an amino group using a pH adjuster (eg, ammonia, sodium hydroxide, amines) in a known manner under alkaline or acidic conditions. It is prepared by Preferred in the present invention are melamine formaldehyde resins.

The mixing ratio of the acrylic resin component and the amino resin component constituting the water-based metallic coating material (B) of the present invention is suitably mixed in the following ratio based on the weight of the solid content.

Acrylic resin component: about 50 to about 90 parts by weight, preferably about 65 to about 85 parts by weight Amino resin component:
About 10 to about 50 parts by weight, preferably about 15 to about 35 parts by weight When a water-dispersible acrylic resin is used as a component, a water-soluble acrylic resin is also used at the same time, and the ratio is as follows.

Water-dispersible acrylic resin component: about 10 to about 7
0 parts by weight, preferably about 20 to about 50 parts by weight Water-soluble acrylic resin component: about 10 to about 70 parts by weight, preferably about 3
0 to about 50 parts by weight amino resin component: about 10 to about 50 parts by weight, preferably about 15 to about 35 parts by weight As the metallic pigment, known ones can be used, for example, aluminum, copper, brass, mica Flaked metallic powders such as iron oxide, bronze, and stainless steel may be used, and the amount of these powders is preferably about 1 to about 50 parts by weight per 100 parts by weight of the solid content of the thermosetting resin composition.

The aqueous metallic paint (B) can be applied in the same manner as the non-metallic paint (A).
The viscosity at the time of coating is about 10 to about 40 seconds (20 ° C) with a Ford cup # 4, and the coating film thickness is about 5 to 5
About 25 μm is preferred.

In the present invention, the non-metallic paint (A)
And the aqueous metallic paint (B) preferably have an affinity. Specifically, a part or all of the thermosetting resin compositions contained in both paints are common or similar, or different. Even so, it is desirable that both have an affinity.

Transparent thermosetting paint (C): The transparent thermosetting paint (C) (hereinafter sometimes abbreviated as “top coat”) is an uppermost layer on the surface of the aqueous metallic paint (B). This is a paint that forms a transparent coating to be applied as a coating. Therefore, it is preferable that the top coat forms an excellent coating film such as gloss, weather resistance, acid resistance, alkali resistance, solvent resistance, hot water resistance, etc. Specifically, acrylic resin (base resin) and amino resin An organic solvent solution type or non-aqueous dispersion type paint containing a thermosetting resin composition comprising a resin (crosslinking agent) as a vehicle component may be mentioned. Further, an ultraviolet absorber, a colorant and the like may be appropriately compounded. it can. From the viewpoint of preventing the occurrence of metallic unevenness, it is preferable to use a vehicle component of the top coat that has poor compatibility with the thermosetting resin composition contained in the aqueous metallic paint. For example, for a system using an acrylic resin as the base resin, the difference between the solubility parameter (SP value) of the acrylic resin of the top coat and the SP value of the acrylic resin of the aqueous metallic paint is about 0.1 to about 1.0. Preferably, there is.

The coating can be performed in the same manner as the non-metallic coating (A). The viscosity at the time of coating is about 10 to about 60 seconds (20 ° C.) with a Ford cup # 4, and the coating thickness is heat-cured coating. About 5 to about 50 μm based on the membrane is preferred.

In the metallic finishing method of the present invention, the non-metallic paint (A) and the aqueous metallic paint (B) described above are applied, preheated at about 60 to about 100 ° C. for about 5 to about 20 minutes, and This is performed by simultaneously applying the curable coating material (C) and heating at about 100 to about 180 ° C. for about 15 to about 45 minutes to simultaneously cure the three coating films.

In the thus finished metallic coating film, the metallic pigment is oriented parallel and uniformly to the coating surface despite the high non-volatile content at the time of coating of the metallic coating material (B) (metallic unevenness is low). No), and a high definition with excellent smoothness.

[0065]

According to the metallic finishing method of the present invention, since the non-metallic paint (A) contains specific crosslinked fine particles, the aqueous metallic paint (B) overlaid on the non-metallic paint (A) It is extremely effective in preventing cracks.

[0066]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples. In Examples, "parts" and "%" indicate "parts by weight" and "% by weight" unless otherwise specified.

Production of Non-Metallic Paint (A) (1) Production of Fine Polymer Dispersion (c) Production Examples 1 to 6 In a 5 L flask equipped with a stirrer, thermometer, condenser and heating mantle, see Table 1. The indicated amount of deionized water and Table 1
Was added in an amount shown in Table 1, and the temperature was raised to 90 ° C. while stirring. 33% of an aqueous solution obtained by dissolving 10 parts of the polymerization initiator shown in Table 1 in 400 parts of deionized water
Was added. After 15 minutes, the dropping of the mixture of monomers and the polymerization initiator shown in Table 1 was started. The dropping of the monomer mixture was performed in 4 hours, and the dropping of the polymerization initiator was performed over 4.5 hours, and the polymerization temperature was maintained at 90 ° C. After the completion of the dropwise addition of the polymerization initiator aqueous solution, the mixture was heated for 30 minutes, kept at 90 ° C., cooled to room temperature, taken out using a filter cloth, and solidified to a solid content of 15%.
% Of aqueous polymer fine particle aqueous dispersions MG1 to MG6.

Each of these aqueous dispersions MG1 to MG6 was dried on a stainless steel vat in an electric hot air dryer at 60 ° C., and was taken out as a solid resin. Thereafter, the polymer fine particle solvent dispersion YG1 having a solid content of 10% was dispersed in a propylene glycol monomethyl ether solvent.
To YG6 were prepared. Polymer fine particle aqueous dispersion M
G1 to MG6 aqueous dispersion and polymer fine particle solvent dispersion YG
Table 1 shows the properties of 1 to YG6.

[0069]

[Table 1]

In Table 1, (Note 1) 1,6-HDDA: 1,6-hexanediol diacrylate IBX: isobornyl methacrylate CHMA: cyclohexyl methacrylate CHA: cyclohexyl acrylate TCDA: tricyclodecane triacrylate IBXA: isovol Nyl acrylate St: Styrene MMA: Methyl methacrylate n-BA: n-butyl acrylate K-180: Latemul K-180, trade name, Kao Corporation
Co., Ltd., quaternary ammonium salt-based allyl group-containing cationic reactive emulsifier, 25% aqueous solution VA-086: trade name, manufactured by Wako Pure Chemical Industries, Ltd., water-soluble azoamide polymerization initiator, 2,2′- Azobis [2-methyl-N- (2-hydroxyethyl) -propionamide] (Note 2) Polymerization stability at the time of emulsion polymerization: After the emulsion polymerization is completed, when the fine particle polymer is filtered through a 100-mesh stainless steel screen, a stainless steel screen is used. After the coagulum remaining on the top was thoroughly washed with water, the weight was measured, and the weight was evaluated as a percentage of the charged monomer.

◎: This percentage is 0.5% or less. ：: This percentage is 0.5 to 2%. Δ: This percentage is 2 to 5%. X: This percentage is 5% or more. Particle size of the fine particle polymer: The aqueous dispersion was diluted with deionized water and measured with a Coulter Nanosizer N-4. (Note 4) The particle size of the fine particle polymer in the solvent dispersion: Dilute with acetone and use Coulter Nanosizer N-4
(2) Production of film-forming binder resin (a) Production Example 7 15 parts of styrene, 20 parts of methyl methacrylate, 46 parts of ethyl acrylate, 1 part of hydroxyethyl acrylate
5 parts and 4 parts of acrylic acid were polymerized in xylene using a polymerization initiator α, α′-azobisisobutyronitrile to obtain an acrylic resin solution having a resin solid content of 70%. The acrylic resin had a number average molecular weight of about 20,000 and an acid value of 31.1 mgKOH / g.

To 100 parts of the resin solid content of the acrylic resin solution obtained above, 5 parts of dimethylaminoethanol (neutralization equivalent: 1.01) was added for neutralization, and the resin solid content was reduced to 50% with isobutyl alcohol. To obtain a neutralized acrylic resin solution (a-1).

(3) Non-metallic paints (A-1) to (A)
Production of -7) Production Examples 8 to 14 Each component was mixed in the composition shown in Table 2, and the viscosity was 17.5 seconds with isopropyl alcohol (Ford cup # 4/20 ° C).
To obtain non-metallic paints (A-1) to (A-7).

[0074]

[Table 2]

Production of aqueous metallic paint (B) (1) Production of aqueous solution of water-soluble acrylic resin (W-1) Production Example 15 15 parts of styrene, 20 parts of methyl methacrylate, 25 parts of ethyl acrylate, 20 parts of butyl acrylate, hydroxyethyl 15 parts of acrylate and 5 parts of acrylic acid are polymerized in a butyl cellosolve using a polymerization initiator α, α′-azobisisobutyronitrile, and the resin solid content is 70%.
Acrylic resin solution was obtained. After adding 4.3 parts of dimethylaminoethanol to 100 parts of the acrylic resin solution thus obtained, water was added to obtain a water-soluble acrylic resin aqueous solution (W-1) having a solid content concentration of 55%.

(2) Production of water-based metallic paint (B-1) Production Example 16 55% aqueous water-soluble acrylic resin aqueous solution (W-1) (Production Example 15) 100 parts 100% Cymel 350 25 parts The above components were mixed. The following aluminum paste dispersion liquid Aluminum paste # 4919 (Toyo Aluminum Co., Ltd. product) 10 parts Aluminum paste # 55-519 (Toyo Aluminum Co., Ltd. product) 20 parts Isopropyl alcohol 30 parts 16 seconds (Ford Cup # 4/20
° C) to obtain an aqueous metallic paint (B-1).

Production of Transparent Thermosetting Paint (C) (1) Production of Acrylic Resin Solution (T-1) Production Example 17 A cell was placed in a normal acrylic resin reaction vessel equipped with a stirrer, thermometer, reflux condenser, etc. Solvent acetate (40 parts) was charged and heated and stirred. After the temperature reached 135 ° C., the following monomer mixture was added over 3 hours.

Methyl methacrylate 10 parts Isobutyl methacrylate 30 parts n-butyl methacrylate 12 parts 2-ethylhexyl methacrylate 20 parts 2-hydroxyethyl methacrylate 25 parts Methacrylic acid 3 parts Cellosolve acetate 50 parts α, α'-azobisisobutyronitrile 4 After the addition of the above monomer mixture, the reaction was continued at 135 ° C., and then a mixture consisting of 10 parts of cellosolve acetate and 0.6 part of α, α′-azobisisobutyronitrile was added.
The addition took 30 minutes. Then, after reacting for 2 hours, cellosolve acetate was distilled off under reduced pressure to prepare a resin solid content of 65%, thereby producing an acrylic resin solution (T-1). The number average molecular weight (measured by vapor pressure osmosis method) of the resin component of the acrylic resin solution (T-1) is 6,100, and the viscosity of the acrylic resin solution is Z2 (Gardner bubble viscosity, 25%).
° C).

(2) Acrylic resin non-aqueous dispersion (N-1)
Production Example 18 126 parts of melamine, butylformaldehyde (40%)
412 parts, 190 parts of n-butanol and 36 parts of xylene were charged into a reaction vessel, and the mixture was heated and reacted for 7 hours while separating the distilled water with a water separator.
After removing 0 parts of the distillate, 50 parts of a hydrocarbon solvent "Shellsol 140" (product of Shell Petroleum Co., Ltd.) and 50 parts of n-heptane are added, a resin content of 60%, a varnish viscosity J (Gardner bubble) (Viscosity, 25 ° C.).

A reaction vessel was charged with 58 parts of the melamine resin solution, 30 parts of n-heptane, and 0.15 part of benzoyl peroxide, heated to 95 ° C., and the following monomer mixture was added dropwise over 3 hours.

Styrene 15 parts Acrylonitrile 9 parts Methyl methacrylate 13 parts Methyl acrylate 15 parts n-butyl methacrylate 1.8 parts 2-hydroxyethyl methacrylate 10 parts Acrylic acid 1.2 parts Benzoyl peroxide 0.5 parts n-butanol 5 parts "Shellsol 140" 30 parts n-heptane 9 parts One hour after the completion of the dropwise addition of the monomer mixture, t-
0.65 parts of butyl peroctoate, "Shellsol 1
3.5 parts of the mixture were added dropwise over 1 hour. Thereafter, stirring was continued for 2 hours while maintaining the temperature at 95 ° C. Thereafter, the pressure was reduced to remove 34 parts of the solvent, and the resin solid content was 60%.
An acrylic resin non-aqueous dispersion (N-1) having a varnish viscosity A (Gardner bubble viscosity, 25 ° C.) was obtained.

(3) Production of Transparent Thermosetting Paint (C-1) Production Example 19 65% acrylic resin solution (T-1) (Production Example 17) 108 parts 70% "Uban HS" (Mitsui Chemicals, Inc.) Product, melamine resin) 43 parts 60% acrylic resin non-aqueous dispersion (N-1) (Production Example 18) 54 parts 1% “Reybo No. 3” (manufactured by Reybo Chemical Co., Ltd., silicone additive) 0. 1 part A transparent thermosetting paint is obtained by dispersing and dispersing with the above composition, and then a viscosity of 35 seconds (Ford cup # 4/20 ° C.) with a mixed solvent consisting of 35 parts of naphthesol # 150, 35 parts of butyl cellosolve, and 30 parts of n-butanol. This was adjusted to obtain a transparent thermosetting paint (C-1) having a solid content of 53%.

Examples 1 to 5 and Comparative Examples 1 to 2 A polybutadiene-based electrodeposition paint was applied on a 0.8 mm thick dull copper plate which had been subjected to zinc phosphate conversion treatment to a dry film thickness of about 20 μm. After baking at 170 ° C for 20 minutes,
Sharpen with 400 sandpaper and wiped with petroleum benzene to degrease. Then, air-coating the middle coat surfacer for automobiles to a dry film thickness of about 25 μm.
After baking at 0 ° C. for 30 minutes, it was ground with a # 400 sandpaper and drained and dried. Then, it was degreased with petroleum benzene to obtain a test material. Next, the above-mentioned non-metallic paints (A-1) to (A-7) were applied to the above-prepared raw materials in a coating booth at a humidity of 60 to 80%, respectively, using Minibell G (manufactured by Nippon Randsburg Co., Ltd., (Electrocoating machine), and dried at room temperature for 2 minutes to obtain a dry film thickness of 5 to 10 μm.
(Electrostatic Air Spray, manufactured by Landsberg Co., Ltd.) and applied to a dry film thickness of 10 to 15 μm, allowed to stand at room temperature for 3 minutes, preheated at 80 ° C. for 10 minutes, and furthermore, a transparent thermosetting paint (C-1) having a dry film thickness of 35 to 40 μm
Was applied using a mini bell G. Then, after leaving it at room temperature for 10 minutes, it is heated at 140 ° C. × 30 with an electric hot air dryer.
Heat cured for minutes. Table 3 shows the cracks and recoat adhesion of the aqueous metallic coating film obtained. The test method in Table 3 is as follows.

Cracking of the aqueous metallic coating film: The obtained coated plate was visually evaluated according to the following criteria.

A: No crack was generated in the aqueous metallic coating film. X: A crack was generated in the aqueous metallic coating film.

Recoat adhesion: 16 baked test plates
Overbake under the condition of 0 ° C x 30 minutes, let cool at room temperature, apply the same kind of paint 2 hours later, bake it at 140 ° C x 30 minutes, let it cool, perform cross cut-cellophane tape peel test, The evaluation was based on the following criteria.

：: No peeling was observed at all, Δ: Slight peeling was observed, ×: Extremely peeling was observed

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[Table 3]

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI B05D 7/24 303 B05D 7/24 303B C09D 5/10 C09D 5/10 133/02 133/02 155/00 155/00 // C08F 2/24 C08F 2/24 A 290/06 290/06

Claims (5)

[Claims] 1. An organic solution-type or non-aqueous dispersion type thermosetting paint (A) containing no metallic pigment is applied to an object to be coated, and a thermosetting aqueous metallic material is applied on the applied paint (A). Apply paint (B), and then apply transparent thermosetting paint (C)
And then simultaneously heating and simultaneously curing the three-layer coating film, wherein the coating material (A) comprises (a) a film-forming binder resin, and (b) a film-forming A volatile organic liquid diluent dissolving a conductive binder (a), and polymer fine particles stably dispersed without being dissolved in a solution of a binder resin (a) in a diluent (b). And (i) a polymerizable monomer having at least two radically polymerizable unsaturated groups in the molecule; and (ii)
(Meth) acrylate having a saturated cyclic group, and (ii)
i) A metallic finishing method characterized by being gelled polymer fine particles obtained by emulsion polymerization of another radically polymerizable unsaturated monomer in the presence of a reactive emulsifier containing an allyl group in the molecule. 2. The method according to claim 1, wherein the film-forming binder resin (a) is a mixture of a neutralized polycarboxylic acid resin having an acid value of 5 to 100 mg KOH / g and an amino resin. 3. A film-forming binder resin (a) 100
The method according to claim 1, wherein 0.1 to 30 parts by weight of the polymer fine particles (c) is blended with respect to part by weight. 4. The (meth) acrylate (ii) having a saturated cyclic group is at least one member selected from the group consisting of cyclohexyl acrylate, cyclohexyl methacrylate, tricyclodecane triacrylate, isobornyl acrylate, and isobornyl methacrylate. Certain claim 1
The described method. 5. The method according to claim 1, wherein the (meth) acrylate (ii) having a saturated cyclic group is isobornyl acrylate and / or isobornyl methacrylate.