JP2003192980A - Bright color base composition for thermosetting solvent type coating used in 3-coat-1-bake finishing for aluminum wheel and coating film forming method using thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a new bright color base composition for a thermosetting solvent type coating for an aluminum wheel. <P>SOLUTION: In the step of coating successively a primer, a color base, and a top clear on the surface of the aluminum wheel and finally conducting the baking, the bright color base composition for a thermosetting solvent type coating is used in the 3-coat-1-bake finishing for the aluminum wheel. The color base comprises, characteristically, an acrylic resin (A) as the basic resin component, a polyester resin (B) having a thermosoftening temperature of -70 to -30°C, a curing agent (C) reactive with the crosslinkable functional group of the acrylic resin, a transparent fine-powdered silica and/or alumina (D) having a particle size of 5-50 mμ, at least one kind of brightening materials (E) selected from an aluminum flake pigment, colored aluminum flake pigment, mica pigment, silver-plated glass flake, alumina flake, silica flake, stainless steel flake, plate-shaped iron oxide, and glass flake, and an organic solvent (F) as the essential components. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a coating composition which is used for efficiently forming a coating film having brilliance on an aluminum wheel and exhibits excellent designability and chipping resistance, and a coating composition using the same. The present invention relates to a film forming method.

[0002]

2. Description of the Related Art Wheels for automobiles, which are mounting members for tubes and tires, are made of steel, aluminum or the like. Of these, weight reduction,
Aluminum wheel with excellent corrosion resistance and design
A lot of aluminum (hereinafter abbreviated as “aluminum wheel”) is used, and for protection and aesthetics, this aluminum wheel is usually used as a primer coating, for example, as a thermosetting powder coating or a thermosetting powder coating. After coating with a water-soluble organic solvent-based paint, baking it, and then applying a thermosetting solvent-based color base, and then baking it, a thermosetting acrylic resin-based organic solvent-based clear paint is finally applied as the top coating. . In such multi-layer coating, a method of lowering or reducing the baking after coating each layer has been attempted from the viewpoint of energy saving, but the important purpose of coating aluminum wheels is corrosion resistance, weather resistance, and design. The sex was insufficient. In addition, the chipping resistance was insufficient due to the increase in the total film thickness due to the multilayer process.

[0003]

The object of the present invention is to solve the above problems, to obtain a coating film having good corrosion resistance, weather resistance, designability, and chipping resistance, and to be involved in a multi-layer process. The object is to provide a coating composition capable of simplifying baking of each layer after coating and reducing energy, and a coating film forming method using the same.

That is, the present invention is as follows: 1. In the step of sequentially coating a primer, a color base and a top clear on the surface of an aluminum wheel and finally baking, the color base is made of an acrylic resin (A).
As a base resin component and having a glass transition temperature of -70 to -10.
C. polyester resin (B), curing agent (C) capable of reacting with the crosslinkable functional group of the acrylic resin, transparent fine powder silica and / or alumina (D) having a particle size of 5 to 50 m, aluminum flake pigment, coloring At least one luster pigment (E) selected from aluminum flake pigment, mica pigment, silver-plated glass flake, alumina flake, silica flake, stainless flake, plate-shaped iron oxide, and glass flake, and an organic solvent (F) as essential components. Thermosetting solvent-based paint for use in 3 coat 1 bake finish for aluminum wheels, characterized by containing 2, and (1) thermosetting solvent-based paint primer on the surface of aluminum wheel (2) and then acrylic resin (A) as the base resin component Degree is -7
0 to -10 ° C polyester resin (B), curing agent (C) capable of reacting with crosslinkable functional groups of the acrylic resin, particle size 5 to
50 mμ of transparent fine powder silica and / or alumina (D), aluminum flake pigment, colored aluminum flake pigment, mica pigment, silver plated glass flake,
3 coats for aluminum wheels characterized by containing at least one glittering material (E) selected from alumina flakes, silica flakes, stainless flakes, plate-shaped iron oxide, glass flakes, and an organic solvent (F) as essential components. 1) A thermosetting solvent-based paint used for bake finishing is applied with a bright color base composition, and (3)
The present invention relates to a method for forming a glittering coating film, which comprises sequentially coating a thermosetting solvent-based paint clearer and (4) finally baking.

The color base composition of the present invention can be applied by simplifying the baking of the primer in the previous step, and by applying the clear of the next step and then baking, a coating having an excellent design property can be obtained. Obtainable. Furthermore, the coating obtained has good chipping resistance.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION The thermosetting solvent-based paint glitter color base composition of the present invention comprises an acrylic resin (A) as a base resin component and a polyester resin (B) having a glass transition temperature of −70 to −10 ° C. A curing agent (C) capable of reacting with a crosslinkable functional group of the acrylic resin, transparent fine powder silica and / or alumina (D) having a particle size of 5 to 50 m, aluminum flake pigment, colored aluminum flake pigment, mica pigment, It is characterized by containing at least one glittering material (E) selected from silver-plated glass flakes, alumina flakes, silica flakes, stainless flakes, plate-shaped iron oxide, glass flakes, and an organic solvent (F) as essential components. 3 coats for aluminum wheels 1
It is used for bake finishing.

Acrylic resin (A): Acrylic resin (A)
Is a (co) polymer obtained by a radical (co) polymerization reaction of a radical-polymerizable monomer having an acrylic ester and / or a methacrylic ester as a main component,
It is preferable that the molecule has at least one crosslinkable functional group selected from a hydroxyl group, a carboxyl group, an epoxy group, and an amino group.

Examples of acrylic acid esters and methacrylic acid esters include monoesters of acrylic acid or methacrylic acid and alcohols having 1 to 201 carbon atoms, and specifically, methyl acrylate, methyl methacrylate, and acrylic acid. Examples thereof include ethyl acid, ethyl methacrylate, propyl acrylate, propyl methacrylate, butyl acrylate, butyl methacrylate, hexyl acrylate, hexyl methacrylate, lauryl acrylate, and lauryl methacrylate.

The above-mentioned monomers containing a crosslinkable functional group include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, caprolactone hydroxyethyl acrylate. Rate, caprolactone hydroxyethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate
, Acrylic acid amide, methacrylic acid amide, glycidyl acrylate, glycidyl methacrylate, acrylic acid, methacrylic acid, maleic acid, fumaric acid and the like. Further, in addition to the above, other monomers capable of radical copolymerization with the above monomers, for example, acrylonitrile, methacrylonitrile, styrene, vinyl acetate, vinyl methyl ether, vinyl chloride,
Unsaturated compounds having one or more polymerizable double bonds in one molecule such as vinylidene chloride, ethylene and propylene can be used.

In the acrylic resin (A), the composition ratio of the acrylic acid ester and the methacrylic acid ester to the monomer having a crosslinkable functional group and the other monomer can be arbitrarily selected according to the purpose. Suitable ranges are 20 to 99% by weight, especially 40 to 95% by weight of acrylic acid ester and methacrylic acid ester, and 1 to 80%, especially 5 to 60% by weight of the other monomers, based on the total weight. The number average molecular weight of the acrylic resin component is preferably in the range of about 1,000 to 100,000 and about 3,000 to 50,000. Thermosetting polyester resin (B): The thermosetting polyester resin (B) has a glass transition temperature of -70 to -10 ° C.
Particularly, it is preferably -60 to -30 ° C. When the thermal softening temperature is lower than -70 ° C, the hardness of the coating film is poor, while
If it is higher than 10 ° C, the chipping resistance of the coating film is poor.

The glass transition temperature can be determined by DSC (Inspection Scanning Calorimeter). Further, the thermosetting polyester resin (B) has a crosslinkable functional group such as a hydroxyl group and a carboxyl group.

Examples of the thermosetting polyester resin (B) include those obtained by reacting a polyhydric alcohol and a polybasic acid.

The polyhydric alcohol is a compound having two or more alcoholic hydroxyl groups in one molecule, and examples thereof include ethylene glycol, diethylene glycol, propylene glycol, butanediol, 1,6-hexanediol, pentanediol and 2,2. -Dimethylpropanediol, glycerin, trimethylolpropane, pentaerythritol and the like. A polybasic acid is a compound having two or more carboxyl groups in one molecule, such as phthalic acid, isophthalic acid, tetrahydrophthalic acid,
Hexahydrophthalic acid, maleic acid, succinic acid, adipic acid, sebacic acid, trimellitic acid, pyromellitic acid,
These anhydrides etc. are mentioned. Furthermore, in the esterification reaction of these polyhydric alcohol and polybasic acid, a monohydric alcohol or a monoepoxy compound having a glycidyl group is used as a part of the alcohol component and / or a part of the acid component, if necessary. As the base, a monobasic acid such as benzoic acid or t-butylbenzoic acid can be used. Also,
Polyester resin is castor oil, tung oil, safflower oil,
Polyester resins modified with oil components such as soybean oil, linseed oil, tall oil, coconut oil or their fatty acids are also included. These polyester resins are generally 500 to 10
It can have a number average molecular weight in the range of 000.

The thermosetting polyester resin (B) is 2
-200 mgKOH / g, preferably 3-70 mgKO
It can have an acid number in the range of H / g. Further, the thermosetting polyester resin (B) is 10 to 200 mg.
It may have a hydroxyl value in the range of KOH / g, preferably 20-120 mg KOH / g. Curing agent (C): The curing agent (C) is the acrylic resin (A).
It is a curing agent having a functional group capable of reacting with the crosslinkable functional group of. The curing agent (C) can also react with the functional group contained in the polyester resin (B). As the curing agent (C), for example, one or more selected from amino resins, polyisocyanate compounds, blocked polyisocyanate compounds and polycarboxylic acid compounds are preferably used. The amino resin reacts with the base resin by heating to form a three-dimensional cured coating film. Examples of the amino resin include a methylolated amino resin obtained by the reaction of an aldehyde with an amino component such as melamine, urea, benzoguanamine, acetoguanamine, steroganamin, spiroguanamine, and dicyandiamide. Examples of the aldehyde include formaldehyde, paraformaldehyde, acetaldehyde, benzaldehyde and the like. Further, the methylolated amino resin which is etherified with a suitable alcohol can also be used, and examples of the alcohol used for the etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol and i-
Examples include propyl alcohol, n-butyl alcohol, i-butyl alcohol, 2-ethylbutanol, 2-ethylhexanol and the like. As the amino resin, a methylolated melamine resin in which at least a part of a methylol group is alkyl etherified is preferable.

The polyisocyanate compound may be a free isocyanate compound or a blocked isocyanate compound. As the polyisocyanate compound having a free isocyanate group,
Aliphatic diisocyanates such as hexamethylene diisocyanate or trimethylhexamethylene diisocyanate, cycloaliphatic diisocyanates such as xylene diisocyanate or isophorone diisocyanate, organic diisocyanates such as tolylene diisocyanate and 4,4′-diphenylmethane diisocyanate Diisocyanate itself, or excess amount of each of these organic diisocyanates and polyhydric alcohol,
Low molecular weight polyester resin or adduct with water, etc., or polymers of each organic diisocyanate listed above,
Further, there are isocyanate and burette compounds, and typical examples of commercially available products thereof are "Barnock D-750, -800, DN-950, -970 or 15-455" (above, Dainippon Ink and Chemicals). Industry Co., Ltd.
Product), "Dismodule L, N, HL, or N
3390 "(product of Bayer, West Germany)," Takenate D-102, -202, -110 or -123.
N "(a product of Takeda Pharmaceutical Company Limited)," Coronate EH,
L, HL or 203 "(product of Nippon Polyurethane Industry Co., Ltd.) or" Duranate 24A-90CX "
(Asahi Kasei Co., Ltd. product) and the like.

Examples of the blocked polyisocyanate compound include those obtained by blocking the above-mentioned polyisocyanate compound having a free isocyanate group with a known blocking agent such as oxime, phenol, alcohol, lactam, malonic acid ester and mercaptan. Examples of the polycarboxylic acid include polycarboxylic acid resins (acrylic resins, polyester resins, etc.), polycarboxylic acid compounds (eg adipic acid, sebacic acid, phthalic acid, etc.) and the like.

Transparent fine powder silica and / or alumina (D): As the transparent fine powder silica and / or alumina (D), the particle size is 5 to 50 mμ, particularly 5 to 30 mμ.
Used. If the particle size is less than 5 mμ, the atomization during coating is insufficient and the resulting coating film has poor smoothness.
When it is more than mμ, the design property of the baked coating film after coating is poor.

Luster material (E): As the luster material (E), aluminum flake pigment, colored aluminum flake pigment, mica pigment, silver-plated glass flake, alumina flake, silica flake, stainless flake, plate-shaped iron oxide, glass flake Use one or more.

The glittering material has an average particle size of 3 to 60 μm, preferably 10 to 40 μm, and a thickness of 0.1 to 3.0 μm.
m, preferably 0.3 to 2.0 μm. If the average particle size is less than 3 μm, the brilliance is poor, while if it exceeds 60 μm, the gloss is poor.

Organic solvent (F): As the organic solvent (F), the above-mentioned resin (A), (B) and resin (C) components are dissolved or dispersed and do not substantially react with these resins. Any material can be used without particular limitation. Examples of the organic solvent include hydrocarbon solvents such as heptane, toluene, xylene, octane and mineral spirit, ester solvents such as ethyl acetate, n-butyl acetate, isobutyl acetate, methyl cellosolve acetate and butyl carbitol acetate, methyl ethyl ketone. , Ketone-based solvents such as methyl isobutyl ketone and diisobutyl ketone, alcohol-based solvents such as methanol, ethanol, isopropanol, n-butanol, sec-butanol and isobutanol, n-butyl ether, dioxane, ethylene glycol monomethyl ether, ethylene glycol monoethyl An ether solvent such as ether can be used.

The blending ratio of each component in the composition of the present invention is 30 to 200 parts by weight, particularly 50 to 100 parts by weight of the component (B) per 100 parts by weight of the component (A) as a solid content.
100 parts by weight, and the total amount of (A) component + (B) component
10 to 100 parts by weight of component (C), especially 1 part by weight
5 to 60 parts by weight, and further (A) component + (B) component +
(D) component 1 per 100 parts by weight of the total amount of component (C)
-15 parts by weight, particularly 2-10 parts by weight is preferred. If the amount is out of these ranges, the metallic design, the finished luster, the chipping resistance, and the coating film hardness decrease.

The component (E) is the component (A) + (B)
1 to 100 per 100 parts by weight of the total amount of + (C) component
Weight part, especially 2-30 weight part is preferable. If the amount is less than 1 part by weight, the design properties such as metallic feeling, luster and gloss are deteriorated, while if it exceeds 100 parts by weight, the finished gloss feeling and chipping resistance are deteriorated.

Further, the component (F) is preferably blended in a range of 30 to 80% by weight, particularly 40 to 70% by weight, in terms of solid content of coating viscosity of the composition. In the composition of the present invention, a pigment (for example, an organic pigment (for example, a quinacridone such as quinacridone, an azo such as Pigment Red, a phthalocyanine blue, a phthalocyanine blue such as phthalocyanine blue, or the like)), an inorganic pigment (for example, titanium oxide) , Calcium carbonate, barita, clay, talc,
Silica, etc., carbon-based pigments (for example, carbon black,
Graphite, etc.), curing catalyst (dibutyltin diacetate, dibutyltin dilaurate, triethylamine, diethanolamine, etc.), ultraviolet absorber (benzophenone compound, benzotriazole compound, salicylate compound, oxalic acid anilide compound, etc.), ultraviolet light Additives such as stabilizers (hindered amine compounds), antioxidants (phenol compounds, organic sulfur compounds, phosphite compounds, etc.), surface conditioners, anti-armpits agents, etc. can be added. The composition of the present invention is used as a paint for a base coat which is finished by a three-coat one-bake method for aluminum wheels. Next, the components of each layer used in the method for forming a glittering coating film of the present invention will be described below.

In the method of the present invention, the surface of an aluminum wheel is coated with (1) a thermosetting solvent type paint primer,
(2) Next, the acrylic resin (A) as a base resin component, a polyester resin (B) having a heat softening temperature of -70 to -30 ° C, and a curing agent (C) capable of reacting with the crosslinkable functional group of the acrylic resin. , Transparent fine powder silica and / or alumina (D) having a particle size of 5 to 50 mμ, aluminum flake pigment having an average particle size of 3 to 60 μm, colored aluminum flake pigment, mica pigment, silver plated glass flake, alumina flake, silica flake, 3 coat 1 bake finish for aluminum wheels characterized by containing at least one glittering material (E) selected from stainless steel flakes, plate-shaped iron oxide and glass flakes and an organic solvent (F) as essential components A thermosetting solvent-based paint is applied with a bright color base composition, and (3) a thermosetting solvent-based paint clear is applied. This is a method for forming a glittering coating film, in which (4) the final coating is performed by sequentially coating. Aluminum wheel: The aluminum wheel is an automobile wheel which is a mounting member for automobiles such as passenger cars, automobiles, trucks and wagons, and tires, and is mainly composed of aluminum, or magnesium. It is made of an alloy containing silicon, silicon, etc., and can be molded into any shape for the purpose of weight reduction and design. It also includes an aluminum wheel in which a shot-blasted uneven casting surface and a cut smooth surface are mixed. It is preferable that the surface of the aluminum wheel is subjected to a chemical conversion treatment with a chromate or a phosphate prior to coating.

Thermosetting solvent-based paint primer: As the primer, a known thermosetting resin solvent-based paint that is usually used as a primer for aluminum wheels can be applied. For example, it is preferable to use an epoxy resin as the thermosetting resin component for the thermosetting resin solvent-based paint having good corrosion resistance. The epoxy resin is a compound having an average of two or more epoxy groups in one molecule, and conventionally known compounds such as liquid epoxy resin and solid epoxy resin can be used without particular limitation. When a solid epoxy resin is used, the resin is used after being dissolved or dispersed in an organic solvent capable of dissolving or dispersing. Specific examples of the epoxy resin include, for example, an epoxy containing an alicyclic epoxy group (an epoxy group on an alicyclic hydrocarbon ring, an epoxy group directly bonded to a carbon atom forming an alicyclic hydrocarbon ring). A resin (a), an epoxy resin (b) containing an aliphatic epoxy group (an epoxy group other than the above and present on a linear hydrocarbon) and an aliphatic or alicyclic epoxy group. An epoxy resin (c) can be used.

The epoxy resin (a) is, for example, a homo-radical polymer of a radical-polymerizable monomer (3,4-epoxycyclohexylmethyl (meth) acrylate) containing an alicyclic epoxy group, the monomer and other monomers. Copolymer with radically polymerizable monomer (for example, alkyl or cycloalkyl ester of (meth) acrylic acid having 1 to 24 carbon atoms, styrene, etc.), 3,4-epoxy-cyclohexylmethyl-3,4-epoxycyclohexanecarboxylate , Bis (2,3-epoxy-cyclopentyl) ether, dicyclopentadiene dioxide, ethylene glycol bis (3,4-epoxy-cyclohexylmethyl), 3,4-epoxy-6-methylcyclohexylmethyl-3,4- Epoxy-cyclohexanecarboxylate Bis (3,4-epoxy - cyclohexylmethyl) adipate, bis (3,4-epoxy-6-methylcyclohexyl methyl) adipate,
3,4-epoxy-cyclohexenecarboxylic acid ethylene glycol diester, bis (3,4-epoxy-cyclohexyl) acetal, 3,4-epoxy-cyclohexylmethyl-3,4-epoxy-cyclohexylmethyl-ε-caprolactone-modified-3, 4-epoxy-cyclohexyl carboxylate, 3,4-epoxy-cyclohexyl vinyl, 3,4-epoxy-cyclohexylmethyl (meth) acrylate, 3,4-epoxy-cyclohexylmethyl-ε-caprolactone-modified (meth) acrylate and the like can be mentioned. To be

The epoxy resin (b) is, for example, a homo-radical polymer of a radical-polymerizable monomer containing an aliphatic epoxy group (glycidyl (meth) acrylate, etc.), the monomer and another radical-polymerizable monomer (eg, C1-C24 alkyl or cycloalkyl ester of (meth) acrylic acid, hydroxyl group-containing unsaturated monomers such as hydroxyethyl (meth) acrylate, aromatic compounds such as styrene, and (meth) acrylonitrile Nitrile compounds etc.), bisphenol type epoxy resin, novolac type epoxy resin, ε-caprolactam modified bisphenol type epoxy resin, (poly) ethylene glycol diglycidyl ether, (poly) propylene glycol diglycidyl ether, neopentyl Glycol di Glycidyl ether, trimethylolpropane triglycidyl ether and the like.

The epoxy resin (c) is, for example, a radical polymerizable monomer containing an aliphatic epoxy group,
Examples thereof include a radical copolymer with a radical-polymerizable monomer having an alicyclic epoxy group, a copolymer with the above-mentioned other radical-polymerizable monomer as necessary, and vinylcyclohexene diepoxide. Further, as the epoxy resin, for example, Epicote 100
1, epicote 1002, same as left 1004, same as left 100
7, Same as left 1009, Same as left 1010 (above, Yuka Shell Epoxy Co., Ltd.), Araldite GY-6084, Same as left 6097, Same as left 6099 (Ciba-Geigy), D
ER-662, same as left 664, same as left 667 (manufactured by Dow Chemical Co.), Epotote YD-012PK, same as left YD-0.
14D, same left YD-909, same left YD-6020 (manufactured by Tohto Kasei Co., Ltd.), etc., bisphenol-epichlorohydrin type epoxy resin, EPPN-201, same left 202,
EOCN-1020, same as 102S (above, manufactured by Nippon Kayaku Co., Ltd.), etc., novolac type epoxy resin, Epolide GT300 (manufactured by Daicel Chemical Industries, Ltd., trade name,
Trifunctional alicyclic epoxy resin), Epolide GT400
(Trade name, tetrafunctional alicyclic epoxy resin manufactured by Daicel Chemical Industries, Ltd.), EHPE (trade name, trifunctional alicyclic epoxy resin manufactured by Daicel Chemical Industries, Ltd.) and the like.

As the hardener component of the epoxy resin, the above-mentioned amino resin or phenol resin can be used.

As the phenol resin, a phenol resin obtained by reacting phenols with formaldehyde can be used. Examples of phenols used to obtain the above-mentioned phenol resin include phenol, methylphenol, ethylphenol, n-propylphenol, isopropylphenol, n-butylphenol, p-tert-butylphenol, p-tert-amylphenol, o. -Phenol having one benzene ring in one molecule such as cresol, m-cresol, p-cresol, p-cyclohexylphenol, p-octylphenol, xylenol; phenyl o-cresol, p
-Two benzene rings in one molecule such as phenylphenol.
Phenol having one; bisphenol F, 1,1-bis (4-hydroxyphenyl) ethane, 2,2-bis (4
-Hydroxyphenyl) butane, bis (4-hydroxyphenyl) -1,1-isobutane, bis (4-hydroxy-tert-butyl-phenyl) -2,2-propane, p- (4-hydroxyphenyl) phenol, oxybis (4-hydroxyphenyl), sulfonylbis (4-hydroxyphenyl), 4,4′-dihydroxybenzophenone, bis (2-hydroxynaphthyl) methane and the like can be mentioned.

The primer can be obtained by dissolving or dispersing the above components in a conventionally known organic solvent (aromatic, aliphatic, alicyclic, ester-based, ketone-based, etc.).

In the primer, if necessary, a pigment (for example, an organic pigment (for example, quinacridone type such as quinacridone, azo type pigment such as Pigment Red, phthalocyanine type such as phthalocyanine blue, phthalocyanine blue)),
Inorganic pigments (eg titanium oxide, calcium carbonate, barita, clay, talc, silica, etc.), carbon-based pigments (eg carbon black, graphite etc.), metallic powders (eg mica-like iron oxide, aluminum etc.) and rust prevention Pigments (for example, red iron oxide, strontium chromate, zinc phosphate, etc.), curing catalysts (dibutyltin diacetate, dibutyltin dilaurate, triethylamine, diethylamine, etc.), UV absorbers (benzophenone compounds, benzotriazole compounds) Compound,
Salicylate compounds, oxalic acid anilide compounds, etc.),
Additives such as ultraviolet stabilizers (hindered amine compounds, etc.), antioxidants (phenolic compounds, organic sulfur compounds, phosphite compounds, etc.), surface modifiers, anti-armpits agents, etc. can be added. Thermosetting solvent-based paint Glittering color base composition: The above-described glittering color base composition is used. Thermosetting Solvent Paint Clear: As the solvent-type paint used for the clear, known thermosetting resin solvent-type paints that are usually used as clears for aluminum wheels can be applied. For example, a thermosetting acrylic resin-based paint is suitable as the thermosetting resin solvent-based paint having good smoothness, designability, and weather resistance. Specifically, a thermosetting coating material obtained by dissolving or dispersing an acrylic resin, a crosslinking agent and a pigment (optional component) in an organic solvent is preferable.

As the acrylic resin, an acrylic resin having one or more functional groups selected from a hydroxyl group, an epoxy group and a carboxyl group which form a coating film having excellent weather resistance, smoothness and chemical resistance. Examples thereof include resins and modified resins thereof. As the cross-linking agent, compounds having a functional group capable of undergoing a cross-linking reaction with these functional groups can be used. For example, a methylolated and / or alkyl etherified melamine resin, a polyisocyanate compound, a blocked polyisocyanate can be used. One or more compounds selected from a compound containing a carboxyl group and a compound containing a carboxyl group are preferable. In the thermosetting solvent coating clear, if necessary, a small amount of pigment (for example, organic pigment (for example, quinacridone such as quinacridone, azo such as Pigment Red, phthalocyanine blue, phthalocyanine blue such as phthalocyanine blue, etc.), inorganic pigment ( For example, titanium oxide, calcium carbonate, barita, clay, talc, silica, etc., carbon-based pigments (eg, carbon black, graphite, etc.), curing catalysts (dibutyltin diacetate, dibutyltin dilaurate, triethylamine, diethanolamine, etc.) ),
UV absorbers (benzophenone compounds, benzotriazole compounds, salicylate compounds, anilide oxalate compounds, etc.), UV stabilizers (hindered amine compounds, etc.), antioxidants (phenolic compounds, organic sulfur compounds, phosphite compounds) Compounds), surface conditioners, anti-armpitting agents, and other additives.

The thermosetting solvent paint clear is obtained by dissolving or dispersing the components in an organic solvent.

Next, a method for forming a coating film of the above composition will be described below.

[Formation of Primer Layer by Thermosetting Solvent-Type Coating Primer]: Prior to coating, the aluminum wheel on which the primer layer is formed is pre-formed on its surface with chromate or phosphate. It is preferable to perform a treatment. The thermosetting solvent-based paint primer is preferably applied by airless spray, air spray, electrostatic method or the like.

The viscosity during coating is preferably 5 to 20 seconds / Ford cup # 4/20 ° C., and the thickness of the primer layer is generally 15 to 80 μm, preferably 30 to 60 μm.
Is. If it is 15 μm or less, the rough surface of the aluminum wheel coating surface such as casting surface cannot be sufficiently covered and the final design feeling is impaired, and if it is 80 μm or more, coating film abnormalities such as armpits and sags occur, and the paint Wastes usage. The primer layer may not be dried. In order to improve the glittering design feeling, baking may be performed at a temperature at which the coating thermosetting epoxy resin solvent-based coating material undergoes a curing reaction. The drying temperature is generally about 15 ° C to 150 ° C.

[Formation of Color Base Layer by Thermosetting Solvent-Based Paint Glittering Color Base Composition]: The color base composition is preferably applied by airless spray, air spray, electrostatic method or the like. The viscosity when painting is 5
~ 20 seconds / Ford cup # 4/20 ° C is preferable, and the thickness of the color base layer is generally 10 to 30 µm.
It is preferably 15 to 25 μm. Below 10 μm,
Inferior in metallic design and chipping resistance, and 30 μm
In the above cases, coating film abnormalities such as armpits and sags occur, and the metallic design feel is poor. The color base layer may not be dried. In order to improve the glittering design feeling, baking may be performed at a temperature at which the coating thermosetting acrylic resin solvent-based coating material undergoes a curing reaction. The drying temperature is generally about 15 ° C to 150 ° C.

[Formation of Clear Layer by Thermosetting Solvent-Based Paint Clear]: The thermosetting acrylic resin solvent-based paint clear is preferably applied by airless spray, air spray, electrostatic method or the like.

The viscosity during coating is preferably 15 to 35 seconds / Ford cup # 4/20 ° C., and the thickness of the clear layer is
Generally 15 to 60 μm, preferably 20 to 40 μm
m. When it is 15 μm or less, the design feeling and finished appearance of the final coating film are impaired, and when it is 60 μm or more, coating film abnormalities such as cracking and sagging occur, and the amount of paint used is wasted.

After these coating films are formed, they are finally baked to simultaneously cure the respective coating films. The baking may be performed at a temperature at which each of the coated compositions cures. Generally, as the baking conditions, it is generally considered that about 130 to 200 ° C. and 10 to 60 minutes are sufficient.

Since the present invention has the above-mentioned constitution, it exerts the following effects. The coating composition of the present invention can simplify baking of each layer of a multi-layer coating and reduce energy. 2) The coating film obtained by the coating film forming method of the present invention has excellent corrosion resistance, weather resistance, designability, and chipping resistance.

[0042]

EXAMPLES Next, examples and comparative examples relating to the present invention will be described. As a general rule, both parts and% are based on weight.

Preparation of sample Acrylic resin (A): Stirrer,
Using a four-necked flask equipped with a reflux condenser, a nitrogen blow-in tube and a dropping device, n-butyl acrylate 320 was used.
Parts, hydroxyethyl methacrylate 150 parts, methyl methacrylate 520 parts, acrylic acid 10 parts, xylene 1000 parts and azobisisobutyronitrile 20 parts were reacted to obtain a solid content concentration of 50% and a glass transition temperature. 28
A hydroxyl group-containing acrylic resin solution having a hydroxyl value of 65 at ℃ was obtained. Polyester resin (B-1): hexahydroxyphthalic acid / adipic acid / trimethylolpropane / 1,6 hexanediol = 0.45 / 0.5 / 0.1 / 0.9 raw material molar ratio, solid content concentration 70% , Hydroxyl value = 56 mg KO
H / g, acid value = 8 mg KOH / g, glass transition temperature =-
52 ° C). Polyester resin (B-2): phthalic acid / hexahydroxyphthalic acid / adipic acid / trimethylolpropane /
Neopentyl glycol = 0.4 / 0.15 / 0.35
/0.2/0.8 raw material molar ratio, solid content concentration 70%, hydroxyl value = 101 mgKOH / g, acid value = 10 mgKOH
/ G, glass transition temperature = −17 ° C.). Curing agent (C): U-ban 28-60 (trade name, manufactured by Mitsui Cytec Co., Ltd., butylated methylol melamine, solid content concentration 60%) Preparation of glitter color base composition (2-1): the acrylic resin ( A) 70 parts, polyester resin (B-1) 5
To a solvent-based base obtained by mixing and dispersing 0 parts, 50 parts of a curing agent (C), and 4 parts of Erosil # 200 (trade name, particle size 12 mμ, Japan Aerosil Co., Ltd., transparent fine powder silica resin). After mixing and dispersing 20 parts of aluminum flake paste (manufactured by Toyo Aluminum Co., Ltd., trade name Alpaste TCR2060, solid content 75%), ethyl acetate 7 was added.
0 parts were mixed to obtain a glittering color base (2-1).

Bright color bases (2-2) to (2-1)
Adjustment of 7): Mixing and mixing the solvent-type bases obtained by mixing and dispersing in the proportions (A), (B), (C), and (D) of Table 1 with the glittering agent of Table 1 as a glittering agent, After dispersion, the amounts of ethyl acetate shown in Table 1 were mixed to obtain thermosetting solvent coating bright color bases (2-2) to (2-17).

Example 1 15 seconds / Ford cup # 4/20 on an aluminum cast plate (AC4C, 10 × 70 × 150 mm) which had been subjected to a chemical conversion treatment with chromate chromate (AL-1000: trade name of Nippon Parkerizing Co., Ltd.). Drying film thickness of # 550 primer (thermosetting epoxy resin solvent type paint for aluminum wheels, trade name, manufactured by Kansai Paint Co., Ltd.) whose viscosity was adjusted to ℃ 40
It was air-sprayed so as to have a thickness of μm and left standing at 25 ° C. for 3 minutes. On top of that, as a glitter color base composition, a thermosetting solvent paint glitter color base (2-1) whose coating viscosity was adjusted to 10 seconds / fod cup # 4/20 ° C. was air sprayed to a dry film thickness of 20 μm. Then, it was allowed to stand at 25 ° C. for 3 minutes. Furthermore, 25 seconds / Ford Cup # 4
MAGICRON ALC-2-1 (thermosetting acrylic resin solvent type paint for aluminum wheels, trade name, manufactured by Kansai Paint Co., Ltd.) adjusted to / 20 ° C. is air-sprayed to a dry film thickness of 30 μm. After standing at ℃ for 3 minutes,
Finally, it was baked at 140 ° C. for 20 minutes. Table 2 shows the layer structure of the obtained coating film.

Examples 2 to 14 (2-2) having the composition shown in Table 1 as a glitter color base
~ (2-14) was used, and coating was repeated in the same manner as in Example 1 to obtain coating films of Examples 2 to 14 having the layer constitution shown in Table 2.

Example 15 A recoating having the same layer constitution as in Example 1 except that (2-1) was used as the glitter color base composition and the drying condition of the glitter color base composition was allowed to stand at 140 ° C. for 3 minutes. The coating film of Example 15 was obtained.

Comparative Examples 1 to 3 Table 2 after coating was repeated in the same manner as in Example 1 except that the glittering color bases (2-15) to (2-17) for comparative examples shown in Table 1 were used. The coating films of Comparative Examples 1 to 3 having a layer structure were obtained.

The following tests were conducted on the obtained test pieces. Metallic feel of the coating design: The metallic feel was visually evaluated according to the following criteria. ○: The arrangement of aluminum pigments was parallel and good. △: The arrangement of aluminum pigments was disturbed and slightly darkened. ×: The arrangement of aluminum pigments was bad. Disturbance Blackness is large and poor appearance of finished coating film: The finished appearance of the coating film was evaluated according to the following criteria from glossiness. ◯: Good, Δ: Slightly bad, ×: Poor (3) Chipping property: US Q-PANEL, Q-G
Install the test plate on the specimen holder of the -R gravel meter (chipping test equipment), and spray 50g of crushed granite stone No. 7 on the coated surface with compressed air of 4kg / cm2 at -20 ° C. The number of scratches on the coating film, the size of the damaged part, and the state of the coating film are visually observed and evaluated. The evaluation was performed based on the following criteria. The better the score is 1, the better 1.0
(Scratches with a diameter of 1.0 mm or less and few scratches), 1.5 (Scratches with a diameter of 1.0 mm or less and many scratches), 2.0 (for scratches) Diameter is 1.5-2
mm (with a small number of scratches), 3.0 (a diameter of a scratched portion is 1.5 to 2 mm, with a large number of scratches), 3.
5 (the diameter of the scratched portion is 2 to 3 mm and the number of scratches is small) 4.0 (the diameter of the scratched portion is 2 to 3 mm and the number of scratches is large), 5.0 (the diameter of the scratched portion) Is 3 mm or more and has a large number of scratches) (4) Pencil scratch value: It was based on JIS K-5400. The evaluation was performed by the shake method. Table 1

[0050]

[Table 1]

Table 2

[0052]

[Table 2]

Continued front page    F-term (reference) 4D075 AE03 AE07 AE09 AE12 BB26Z                       CA02 CA04 CB04 CB06 CB13                       DA15 DA23 DB07 DC13 EA07                       EA43 EB22 EB32 EB33 EB35                       EB38 EB45 EB53 EC02 EC03                       EC04 EC11 EC23 EC30 EC53                 4J038 CG001 DD002 HA066 HA216                       HA446 KA03 KA06 KA20                       MA13 NA21 PA19 PB05 PC02

Claims (2)

[Claims] 1. A primer, a color base, and a top clear are sequentially coated on the surface of an aluminum wheel, and in the final baking step, the color base has an acrylic resin (A) as a base resin component and a glass transition temperature of -7.
0 to -10 ° C polyester resin (B), curing agent (C) capable of reacting with crosslinkable functional groups of the acrylic resin, particle size 5 to
50 mμ of transparent fine powder silica and / or alumina (D), aluminum flake pigment, colored aluminum flake pigment, mica pigment, silver plated glass flake,
3 coats for aluminum wheels characterized by containing at least one glittering material (E) selected from alumina flakes, silica flakes, stainless flakes, plate-shaped iron oxide, glass flakes, and an organic solvent (F) as essential components. 1. A thermosetting solvent-based paint glittering color base composition used in 1-baking finish. 2. A surface of an aluminum wheel is coated with (1) a thermosetting solvent-based paint primer, (2) and then,
A polyester resin (B) having an acrylic resin (A) as a base resin component and a glass transition temperature of −70 to −10 ° C., a curing agent (C) capable of reacting with a crosslinkable functional group of the acrylic resin,
Transparent fine powder silica and / or alumina (D) having a particle diameter of 5 to 50 mμ, aluminum flake pigment, colored aluminum flake pigment, mica pigment, silver plated glass flake, alumina flake, silica flake, stainless flake, plate-like iron oxide, Thermosetting solvent-based paint glitter for use in 3 coat 1 bake finish for aluminum wheels, characterized by containing at least one glittering material (E) selected from glass flakes and an organic solvent (F) as essential components A color base composition,
(3) A method for forming a glittering coating film, further comprising sequentially coating a thermosetting solvent type paint clear, and (4) finally baking.