JP3283940B2 - Thermosetting coating composition and method of forming coating - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermosetting coating composition, and more particularly to a coating composition for an automobile body, which is required to have a high coating property such as high aesthetics, weather resistance and acid resistance. The present invention relates to a thermosetting coating composition and a method for forming a coating film, which are suitable for the present invention.

[0002]

2. Description of the Related Art In coatings requiring a high degree of aesthetics and coating performance, for example, in the coating of an automobile body, after applying an electrodeposition coating and an intermediate coating on the body surface, a color pigment or a metallic pigment is formed thereon. In general, a so-called two-coat one-bake method is used in which a base coat paint containing a brightener and a clear coat paint for overcoating are applied in a wet-on-wet manner, and both paints are heated and cured simultaneously. However, they are not always satisfactory in terms of aesthetics and coating film performance.

[0003] Further, as a coating method which satisfies the recent demand for a high degree of aesthetics of automobile body coating and abrasion resistance represented by abrasion caused by a car wash brush of an automobile car washing machine, a clear coat having a specific composition is formed into two coats. A coat / two bake method is known (for example, Japanese Patent Application Laid-Open No. 3-278868).
No.). However, in the coating film obtained by this coating method,
There has been a problem that performances such as acid resistance and weather resistance are somewhat reduced.

[0004]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems in the conventional two-coat, one-bake and three-coat, two-bake coatings, and provides cosmetics, abrasion resistance, and acid resistance. Another object of the present invention is to provide a thermosetting coating composition used for forming a coating film having excellent coating properties such as weather resistance, and a method for forming a coating film using the thermosetting coating composition.

[0005]

That is, the thermosetting coating composition of the present invention comprises (A) (a) a (meth) acrylic acid ester 3 having an alicyclic hydrocarbon substituent or an aromatic hydrocarbon substituent. (B) 10 to 60% by weight of a hydroxyl group-containing (meth) acrylate represented by the following general formula (1);

[0006]

Embedded image CH ₂ ＝ C (R ¹ ) COOR ² (1) (wherein, R ¹ represents a hydrogen atom or a methyl group, and R ² represents a group represented by the following general formulas (2) to (4)). )

[0007]

Embedded image (Wherein, R ³ , R ⁴ , R ⁶ and R ⁷ are a linear or branched alkylene group having 1 to 5 carbon atoms, R ⁵ is a hydrogen atom or a methyl group, j is an integer of 2 to 5, k represents an integer of 1 to 7, m represents an integer of 2 to 10, and n represents an integer of 1 to 3.) (c) 2 to 60% by weight of an aromatic vinyl monomer, and (d) a straight chain having 4 or more carbon atoms. 5 to 50% by weight of a (meth) acrylate having a chain or branched aliphatic hydrocarbon substituent,
(e) 0.3 to 10% by weight of a carboxyl group-containing vinyl monomer, (f) 2 to 40% by weight of a hydroxyl group-containing (meth) acrylate other than the compound represented by the general formula (1),
And (g) a hydroxyl value obtained by copolymerizing 0 to 50% by weight of another vinyl monomer copolymerizable with the above-mentioned components (a) to (f) is 50 to 200 mgKOH / g, and an acid value is 2 to 2. It is characterized by containing 40 to 90% by weight of an acrylic copolymer having a weight average molecular weight of 2,000 to 30,000 and 40 to 90% by weight of an amino resin (B) as essential components.

[0008]

The acrylic copolymer (A) used in the thermosetting coating composition of the present invention comprises the above-mentioned copolymer components (a) to (g) (however, the use of the monomer (g) is optional). Are copolymerized in a specific ratio, having a hydroxyl value of 50 to 200 mgKOH / g and an acid value of 2 to 40 mgKOH / g.

If the copolymer has a hydroxyl value of less than 50 mgKOH / g, the resulting cured coating has a low crosslink density, and thus has a problem of low hardness and low solvent resistance. On the other hand, if the hydroxyl value is more than 200 mgKOH / g, the resulting coating composition will have disadvantages such as a decrease in the solid content of the paint and a decrease in the water resistance of the cured film. Further, the acid value of the copolymer (A) is 2
If the concentration is less than mgKOH / g, the resulting cured film has a low crosslinking density, and causes a disadvantage that the hardness and the solvent resistance are reduced.
If it exceeds 40 mgKOH / g, the water resistance decreases, so that it is not suitable.

The acrylic copolymer (A) is a copolymer component (a)
(G), and as the copolymerization component (a), a (meth) acrylate having an alicyclic hydrocarbon substituent or a (meth) acrylate having an aromatic hydrocarbon substituent is used. . The term "alicyclic" as used herein may mean either a monocyclic structure or a spiro ring structure. Specific examples of the (meth) acrylate having an alicyclic hydrocarbon substituent include cyclopentyl (meth) acrylate, cyclohexyl (meth) acrylate, cycloheptyl (meth) acrylate, cyclooctyl (meth) acrylate, and adamantyl (meth) ) Acrylate, isobornyl (meth) acrylate, methylcyclohexyl (meth)
Acrylate, ethylcyclohexyl (meth) acrylate, methyl adamantyl (meth) acrylate, 4-
Butylcyclohexyl (meth) acrylate, dihydrodicyclopentadienyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, tricyclodecanyl (meth) acrylate, and the like.
In addition, specific examples of the (meth) acrylate having an aromatic hydrocarbon substitution include phenyl (meth) acrylate, naphthyl (meth) acrylate, 4-methylphenyl (meth) acrylate, and the like. Copolymer component
The amount of (a) used is 3 to 40% by weight. If the amount used is less than 3% by weight, the aesthetics of the resulting coating composition will be unsatisfactory, and if it exceeds 40% by weight, the resulting cured film will be too brittle and the weather resistance will be reduced. I do.

The copolymer component (b) is a hydroxyl group-containing (meth) acrylate represented by the general formula (1) and is an important component for improving scratch resistance. Used in If it is less than 10% by weight, the improvement of scratch resistance is insufficient, and if it exceeds 60% by weight, the hardness of the coating film is lowered and the water resistance is also lowered.

Specific examples of the copolymer component (b) include 1 mol of ε-caprolactone to 2-hydroxylethyl methacrylate, 1 mol of γ-butyrolactone to 2-hydroxylethyl methacrylate, and 2-hydroxylethyl acrylate. Ε-caprolactone adduct to 2-hydroxyethyl acrylate
Adducts of hydroxyl-containing (meth) acrylates and organic lactones, such as 3-mol adduct of caprolactone and 2-mol adduct of ε-caprolactone to 2-hydroxylpropyl methacrylate; 2-hydroxylethyl (meth) acrylate or 2-adduct Ring-opening adduct of ethylene oxide or propylene oxide to hydroxylpropyl (meth) acrylate; dimer or trimer of 2-hydroxylethyl (meth) acrylate or 2-hydroxylpropyl (meth) acrylate; More than one species may be used in combination.

As the copolymer component (c), an aromatic vinyl monomer is used in an amount of 2 to 60% by weight, preferably 5 to 30% by weight. If it is less than 2% by weight, the aesthetics of the resulting cured coating film will be unsatisfactory, and if it exceeds 60% by weight, the weather resistance of the coating film will be low. Specific examples of the aromatic vinyl monomer include styrene, α-methylstyrene, vinyltoluene, p-chlorostyrene, and the like. Two or more of these may be used in combination, and among them, styrene, α-methylstyrene And vinyl toluene are preferred.

As the copolymer component (d), a (meth) acrylic acid ester having a linear or branched aliphatic hydrocarbon substituent having 4 or more carbon atoms is used in an amount of 5 to 50% by weight. If the amount used is less than 5% by weight, the aesthetics of the cured film obtained will be unsatisfactory, and if it exceeds 50% by weight, the hardness of the cured film obtained will be insufficient and the solvent resistance will be poor. It will be unsatisfactory. Specific examples of the copolymer component (d) include n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, n-pentyl (meth) acrylate, hexyl (meth) acrylate, Heptyl (meth) acrylate, n-octyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, nonyl (meth) acrylate, isononyl (meth) acrylate, lauryl (meth) acrylate, tridecyl (meth) acrylate,
Cetyl (meth) acrylate, stearyl (meth) acrylate and the like may be mentioned, and these may be used in combination of two or more.

The carboxyl group-containing vinyl monomer used as the copolymer component (e) contains one or more carboxyl groups in the molecule, and specific examples thereof include acrylic acid, methacrylic acid, itaconic acid, and fumaric acid. Acid, crotonic acid, maleic acid, monomethyl itaconate, monobutyl itaconate, monobutyl maleate and the like. The amount used is in the range of 0.3 to 10% by weight. If the amount is less than 0.3% by weight, the crosslinked density of the cured film is low, the solvent resistance is low, and if it exceeds 10% by weight, the water resistance of the film is high. Is reduced. A more preferred range is from 0.5 to 5% by weight.

The copolymerization component (f) is a hydroxyl group-containing (meth) acrylate different from the compound represented by the general formula (1) used as the copolymerization component (b).
It is used in the range of weight%. If the amount is less than 2% by weight, the crosslinked density of the cured coating film is low, the hardness and the solvent resistance are reduced, and the weather resistance is reduced. If the amount exceeds 40% by weight, the cured coating film becomes brittle, the flexibility is reduced, and the water resistance is reduced. Specific examples of the copolymer component (f) include 2-hydroxyethyl (meth) acrylate and 2-hydroxyethyl (meth) acrylate.
Hydroxypropyl (meth) acrylate, 3-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 5-hydroxypentyl (meth) acrylate, 6-hydroxyhexyl (meth) Acrylates and the like may be mentioned, and these may be used in combination of two or more.

The copolymer component (g) comprises the above-mentioned copolymer component (a)
(f) other vinyl monomers copolymerizable with the component,
It is used in the range of 50% by weight. When the amount of the copolymer component (g) is more than 50% by weight, there arises a problem that the aesthetics and weather resistance of the formed coating film are reduced.

As the copolymer component (g), methyl (meth)
Carbon number of acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, i-butyl (meth) acrylate, t-butyl (meth) acrylate, sec-butyl (meth) acrylate (Meth) acrylic esters having 5 or less hydrocarbon substituents; ethylenically unsaturated nitriles such as acrylonitrile and methacrylonitrile; vinyl esters such as vinyl acetate and vinyl propionate;
N-alkoxy-substituted amides such as methoxymethylacrylamide, N-ethoxymethylacrylamide and N-butoxymethylacrylamide; epoxy group-containing ethylenically unsaturated monomers such as glycidyl (meth) acrylate and methallyl glycidyl ether; dimethyl Aminoethyl (meth) acrylate, diethylaminoethyl (meth)
Examples include ethylenically unsaturated basic monomers such as acrylates, and these may be used in combination of two or more.

The method for polymerizing the acrylic copolymer (A) for the base coating in the present invention may be any known polymerization method such as a solution polymerization method, a bulk polymerization method and an emulsion polymerization method. Is preferred.
In the case of the solution polymerization method, the mixture of the copolymer components (a) to (g) is copolymerized in the presence of an organic solvent and a polymerization initiator. Organic solvents include isopropyl alcohol, n
-A commonly used organic solvent such as butanol, toluene and xylene can be used, and a commonly used polymerization initiator such as azobisisobutyronitrile, benzoyl peroxide and cumene hydroperoxide can be used as the polymerization initiator.
If necessary, a chain transfer agent such as 2-mercaptoethanol and n-octylmercaptan can be used.

The weight average molecular weight of the acrylic copolymer (A) is from 2,000 to 30,000. If the weight-average molecular weight is less than 2,000, weather resistance and solvent resistance decrease, and if the weight-average molecular weight exceeds 30,000, cosmetics, especially glossiness, decrease, so that it is not suitable.

The amino resin (B) is a component used as a curing agent. Specific examples thereof include those obtained by subjecting a methylolated product of aminotriazine, urea, dicyandiamide or N, N-ethyleneurea to alkyl etherification with cyclohexanol or an alkanol having 1 to 6 carbon atoms, and in particular, methylol of aminotriazine. A butyl etherified melamine resin obtained by butyl etherification of a compound, a methyl etherified melamine resin obtained by methyl etherification, and the like are preferable.

The amount of the amino resin (B) used is in the range of 10 to 60% by weight. If the amount is less than 10% by weight, the cured coating film has a low crosslinking density, and the hardness and the solvent resistance are insufficient. If the amount exceeds 60% by weight, the cured film becomes brittle and the weather resistance is reduced, and the metallic feeling of the coating film is reduced. , The glossiness is unsatisfactory, and the physical and chemical performances are generally poor.

The coating composition of the present invention comprises an amino resin
You may add 0.05 to 5 weight% of the external acid catalyst with respect to (B). Examples of the acid catalyst include paratoluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, and neutralized products of these amines.

In the coating composition of the present invention, a blocked polyisocyanate may be used as another curing agent in a range of up to 40% by weight. If it exceeds 40% by weight, the hardness and the solvent resistance of the cured coating film decrease, which is not appropriate. Specific examples of the blocked polyisocyanate include aliphatic isocyanates such as tetramethylene diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate; isophorone diisocyanate, 4,4′-
Alicyclic diisocyanates such as methylene bis (cyclohexyl isocyanate); aromatic diisocyanates such as xylylene diisocyanate and tolylene diisocyanate; ethylene glycol to polyisocyanate;
Polyhydric alcohol adducts such as propylene glycol, neopentyl glycol and trimethylolpropane; low molecular weight polyester resins having functional groups that react with isocyanate groups; adducts to polyisocyanates such as water; or burettes; Coalescence;
And the like, in which the isocyanate group of such a compound is blocked with a known blocking agent such as a lower monohydric alcohol, methyl ethyl ketoxime, or acetoacetic ester.

The thermosetting coating composition of the present invention can be applied to an untreated object or an intermediate object by the following method.

In the first method, a paint is prepared by blending a coloring agent and / or a brilliant with the thermosetting coating composition of the present invention, and this is applied to an object to be coated and then cured by heating. This is a method of forming a coating.

In the second method, a base coat paint containing a coloring agent and / or a brightener is applied as an undercoat paint to an object to be coated, and then the thermosetting coating composition of the present invention is used as a clear paint. This is a method of applying a wet-on-wet method, and simultaneously heating and curing both paints to form a film.

A third method is to apply a base coat paint containing a coloring agent and / or a brilliant as an undercoat paint to an object to be coated, and then apply a wet-on-wet method as described in, for example, JP-A-3-278868. 2 disclosed
Apply a clear coat paint consisting of a thermosetting acrylic resin and an amino resin having a class hydroxyl group as a cross-linking seat,
This is a method in which a coating is formed by simultaneously heating and curing both paints, and then the thermosetting coating composition of the present invention is applied thereon and cured by heating to form a coating.

As the coloring agent used in the above,
Titanium oxide, carbon black, quinacridone, cyanine blue and the like can be mentioned, and as the glitter, aluminum paste, mica, flaky iron oxide and the like can be mentioned.

When the thermosetting coating composition of the present invention is used as a clear coat paint, the base coat paint may be used as an undercoat paint and applied in a wet-on-wet manner, or the above-mentioned three coat paint may be used. -It may be used as a clear coat paint for a top coat of a two-bake coating method. As the coating material for the base coat in this case, it is preferable to use a known acrylic copolymer resin as a vehicle, but an alkyd resin can also be used. These vehicles include volatile organic solvents, curing agents, pigments, photovoltaic agents and, if necessary, additives such as polyester resins, epoxy resins, and cellulose resins, surface conditioners, ultraviolet absorbers,
Those to which an antioxidant or the like is added can be used as a base coat paint.

When the thermosetting coating composition of the present invention is used as a clear coat paint, a volatile organic solvent, a surface conditioner, an ultraviolet absorber, a light stabilizer, an antioxidant, a sagging prevention Additives such as agents are used.

[0032]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples.
All based on weight. Reference Example 1 <Synthesis of Acrylic Copolymer Used for Base Coating Paint> 40 parts of toluene and 10 parts of n-butanol were charged into a container provided with a stirrer, a temperature controller and a condenser. The temperature was increased to 100 ° C. while stirring the contents of the vessel. Next, a mixture of a monomer and a polymerization initiator having the following composition was dropped into this solvent mixture over 4 hours, and 0.3 part of benzoyl peroxide was further added. The polymerization addition rate was increased while stirring at the same temperature for 2 hours. After that, 50 parts of toluene was added to complete the polymerization. The weight average molecular weight of the obtained copolymer was 60,000, and this acrylic copolymer solution (nonvolatile content concentration 50%) is hereinafter referred to as "acryl varnish (D)". Styrene 5 parts Methacrylic acid 2 parts Methyl methacrylate 35 parts Ethyl acrylate 46 parts 2-hydroxyethyl acrylate 12 parts Benzoyl peroxide 1.5 parts Reference Example 2 <Production of base coat coating composition> Each component of the composition shown in Table 1 Was placed in a stainless steel container and stirred sufficiently, and then the viscosity was adjusted with a mixed solvent for dilution shown in Table 2 to prepare base coat paints B-1 to B-3.

[0033]

[Table 1] * 1) Butyl etherified melamine resin (Mitsui Toatsu Chemicals)
Nonvolatile content 60% * 2) Methylbutyl mixed etherified melamine resin (Mitsui Cyanamid Co., Ltd.) Nonvolatile content 100% * 3) Aluminum paste (Toyo Aluminum Co., Ltd.)
* 4) Red pigment (manufactured by Tosoh Corporation) * 5) The composition of the mixed solvents (1) and (2) is as shown in Table 2. * 6) Measured at 20 ° C using Ford Cup No4.

[0034]

[Table 2] * 1) A trademark, an aromatic petroleum derivative manufactured by Esso. Synthesis Examples 1 to 7 Solvesso # 100 (trademark, an aromatic petroleum derivative manufactured by Esso Corporation) was charged in a container provided with a stirrer, a temperature controller, and a condenser in the amount shown in Table 3, and heated with stirring to obtain 120. The temperature was raised to ° C. Next, a mixture obtained by adding 2 parts of azoisobutyronitrile and 4 parts of t-butyloxyisopropyl carbonate to 100 parts of the monomer mixture shown in Table 3 was added dropwise over 3 hours. Then
Add 30 parts of azoisobutyronitrile to this mixture in 30 parts.
Added four times at minute intervals. The reaction mixture is further treated at 120 ° C. for two more
After the polymerization addition rate was increased while stirring for a period of time, n-butanol was added in the amount shown in Table 3 to complete the polymerization, and the reaction of P-1 was stopped.
A lylic copolymer solution was obtained . Similarly , P- 2 to P-
Thus, an acrylic copolymer solution of No. 7 was obtained.

The viscosity of the obtained acrylic copolymer solution,
Table 3 shows the nonvolatile content and the acid value and hydroxyl value of the copolymer.

[0036]

[Table 3] * 1) Measured at 25 ° C using a Gardner-Holt foam viscometer. * 2) Measured by gel permeation chromatography and shown as a value based on polystyrene. Reference Example 3 <Manufacture of coating composition for first clear coat used for 3 coat / 2 bake coating> 20 parts of n-butanol and 80 parts of Solvesso # 100 were placed in a container provided with a stirrer, a temperature controller and a condenser. And was charged. The temperature was increased to 120 ° C. while stirring the contents of the vessel. Next, a mixture of the monomer and the polymerization initiator shown in Table 4 was dropped into this solvent mixture over 4 hours, and the polymerization addition rate was increased while stirring at the same temperature for 2 hours, and then the temperature was lowered to complete the polymerization. . The weight average molecular weight of the obtained copolymer is 1
At 5,000, this acrylic copolymer solution was mixed with the additives shown in Table 4 to prepare a first clear coating composition.

[0037]

[Table 4] Examples 1 to 6 and Comparative Examples 1 to 3 The acrylic copolymer solution obtained in Synthesis Examples 1 to 7, the amino resin and other additives were mixed at the ratio shown in Table 5 to obtain a thermosetting coating composition. Prepared. The following coating test was performed using this thermosetting coating composition.

A steel plate treated with zinc phosphate (30 cm × 45 c)
m) is coated with a cationic electrodeposition paint for automobiles,
Bake at 300C for 30 minutes. Then, after applying an intermediate coating composed of an alkyd resin and an amino resin,
After baking, the coating was sanded, polished, and dried.

In Examples 1 to 3 and Comparative Example 1, the base coat paint prepared in Reference Example 2 was spray-coated on the intermediate coating film so as to have a dry film thickness of 20 μm, and left for 3 minutes. The thermosetting coating composition (clear coating composition) shown in No. 3 was overcoated with the combinations shown in Table 5 by a wet-on-wet method so that the dry film thickness became 30 μm. After leaving the undried coating film at room temperature,
It was baked with a hot air drier at 40 ° C. for 25 minutes to form a cured coating film.

In Examples 4 and 5 and Comparative Example 2, the base coat paint was spray-coated on the intermediate coating film so that the dry film thickness became 20 μm and left for 3 minutes. The paints for use were overcoated with the combinations shown in Table 5 by a wet-on-wet method so that the dry film thickness was 30 μm, and baked at 140 ° C. for 25 minutes to form a cured coating film. Next, the composition for thermosetting coating (coating material for clear coating) shown in Table 3 was repeatedly applied so that the dry film thickness became 30 μm, and baked at 140 ° C. for 25 minutes to form a cured coating film.

In Example 6 and Comparative Example 3, a white thermosetting coating composition was applied on the intermediate coating film so as to have a dry film thickness of 30 μm without applying the base coating material.
A coating film was formed in one coat and one bake.

Table 6 shows the evaluation results of the appearance and performance of the obtained coating film. The following criteria were used to evaluate the metallic feeling or uneven color, gasoline resistance, acid resistance, warm water resistance and weather resistance of the cured coating film. Display grade evaluation 4 Very good 3 Good 2 Poor 1 Very bad

[0043]

[Table 5] * 1) Surface conditioner (manufactured by Monsanto) * 2) Dodecylbenzenesulfonic acid * 3) Titanium oxide (chlorination method, manufactured by Ishihara Sangyo Co., Ltd.) * 4) Measured at 20 ° C. using Ford Cup No4.

[0044]

[Table 6] * 1) 1-1: 1 coat and 1 bake method 2-1: 2 coat and 1 bake method 3-2: 3 coat and 2 bake method * 2) Visual judgment (However, in Example 6 and Comparative Example 3, gloss was judged. * 3) 60 ° G: Digital variable-angle gloss meter manufactured by Suga Test Instruments Co., Ltd.
Measured using UGV-4D. * 4) PGD value: Measured using a portable sharpness gloss meter manufactured by Tokyo Koden Co., Ltd. * 5) Uni (made by Mitsubishi Pencil Co., Ltd.) is used. * 6) A 10% sulfuric acid aqueous solution is dripped at a spot, immersed at room temperature for 24 hours, and the appearance is visually determined. * 7) After immersion in warm water of 50 ° C for 10 days, the appearance was visually judged. * 8) After 1000 hours of sunshine weather meter, 50
After 240 hours of humidity test at 98 ° C. and 98% RH, the appearance was visually judged. In Comparative Example 2, cracks occurred. * 8) Using a friction fastness tester (manufactured by Daiei Kagaku Seiki Co., Ltd.), apply gauze to the place in contact with the painted surface, perform a 10-way reciprocal friction test with a load of 1 kg, and visually determine the scar.

As is clear from Table 6, when the thermosetting coating composition of the present invention was used (Examples 1 to 6), coating films having satisfactory appearance and coating performance could be formed. In the coating film obtained using the thermosetting coating composition used in the comparative examples, its aesthetic properties, that is, metallic feeling or uneven color, gloss, sharpness, acid resistance and scratch resistance are unsatisfactory. there were.

[0046]

As is clear from the above examples, the use of the thermosetting coating composition of the present invention can provide a coating film having excellent aesthetics, sufficient coating performance, and durability. .

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification code FI C09D 161/20 C09D 161/20 (72) Inventor Toshinao Harada 4-160 Sunadabashi, Higashi-ku, Nagoya-shi, Aichi, Japan Mitsubishi Rayon Co., Ltd. (56) References JP-A-4-209677 (JP, A) JP-A-61-145260 (JP, A) JP-A-2-51571 (JP, A) (58) Fields studied (Int. Cl. ⁷ , DB name) C09D 133/00-133/26 C09D 161/20-161/32

Claims (4)

(57) [Claims] (A) (a) 3 to 40% by weight of a (meth) acrylic ester having an alicyclic hydrocarbon substituent or an aromatic hydrocarbon substituent, (b) represented by the following general formula (1): 10 to 60% by weight of a hydroxyl group-containing (meth) acrylic acid ester represented by the formula: CH ₂ CC (R ¹ ) COOR ² (1) (wherein, R ¹ is a hydrogen atom or a methyl group, and R ² is Represents a group represented by any one of formulas (2) to (4). (Wherein, R ³ , R ⁴ , R ⁶ and R ⁷ are a linear or branched alkylene group having 1 to 5 carbon atoms, R ⁵ is a hydrogen atom or a methyl group, j is an integer of 2 to 5, k represents an integer of 1 to 7, m represents an integer of 2 to 10, and n represents an integer of 1 to 3.) (c) 2 to 60% by weight of an aromatic vinyl monomer, and (d) a straight chain having 4 or more carbon atoms. 5 to 50% by weight of a (meth) acrylate having a chain or branched aliphatic hydrocarbon substituent,
(e) 0.3 to 10% by weight of a carboxyl group-containing vinyl monomer, (f) 2 to 40% by weight of a hydroxyl group-containing (meth) acrylate other than the compound represented by the general formula (1),
And (g) 0 to 50% by weight of another vinyl monomer copolymerizable with the above components (a) to (f), the hydroxyl value obtained by copolymerization is 50 to 200 mgKOH / g, and the acid value is 2 ~ 40mgKOH / g,
A thermosetting coating composition comprising, as essential components, 40 to 90% by weight of an acrylic copolymer having a weight average molecular weight of 2,000 to 30,000 and (B) 10 to 60% by weight of an amino resin. 2. A film formed by applying a composition obtained by blending a coloring agent and / or a brilliant to the thermosetting coating composition according to claim 1 to an object to be coated, and then heating and curing the composition. Method. 3. A composition for a base coat containing a coloring agent and / or a brilliant is applied to an object to be coated, and then the composition for a thermosetting coating according to claim 1 is applied thereon and further applied. A method for forming a coating film, comprising simultaneously heating and curing the composition. 4. A composition for a base coat containing a coloring agent and / or a brilliant is applied to an object to be coated, and then a coating for a clear coat is applied thereon and cured by heating. A method for forming a coating, comprising applying the thermosetting coating composition as described above onto the obtained coating, and then heating and curing the coating.