JP2000273393A - Coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a coating composition which can form a coating film having a high gloss and excellent polishability and having good resistance to post-unevenness and to sagging and having high finish. SOLUTION: This composition contains (A) a copolymer made from a monomer component comprising 5-60 wt.% (a) styrene, 5-50 wt.% (b) isobornyl (meth) acrylate, 10-40 wt.% (c) hydroxy-containing polymerizable unsaturated monomer, and 0-80 wt.% (d) other polymerizable unsaturated monomers and having a weight average molecular weight of 2,000 to below 20,000 and a hydroxy value of 50-150 mgKOH/g, (B) a copolymer made from a monomer component comprising 5-60 wt.% component (a), 5-50 wt.% component (b), 5-30 wt.% component (c), and 0-85 wt.% component (d) and having a weight-average molecular weight of 20,000-100,000 and a hydroxy value of 20-100 mgKOH/g and (C) a curing agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a coating composition having excellent sag resistance and capable of forming a coating film having excellent finish, especially a coating composition suitable as a clear coating for repair, and this coating composition. And a method for forming a coating film using

[0002]

2. Description of the Related Art As a clear coating for repairing automobile bodies and the like, a coating film having a high gloss and excellent abrasiveness can be formed, and a metallic base coating for wet-on-wet coating. It is necessary that the colored base paint has good return unevenness resistance and sagging resistance, and in recent years, it has been required that a highly finished coating film can be formed.

In order to impart a high finish to a coating film, the resin component of the coating material is reduced in molecular weight from the viewpoint of improving the fluidity of the coating film. , Sagging resistance is reduced and paint tends to drip,
In particular, there is a problem that the coating workability when coating the vertical surface of the object to be coated is poor.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above problems, to form a coating film having high gloss and excellent polishing properties,
An object of the present invention is to provide a paint having good sag resistance and capable of forming a highly finished coating film.

Another object of the present invention is to provide a repair coating method capable of forming a highly finished coating film having high gloss, excellent polishing properties, good return unevenness resistance, and excellent sag resistance.

[0006]

Means for Solving the Problems The present inventors have used a hydroxyl group-containing copolymer containing styrene and isobornyl (meth) acrylate as a part of a constituent monomer component as a base resin, and have used a low-molecular-weight copolymer as the copolymer. The inventors have found that the object can be achieved by using a combination of a high molecular weight compound and a high molecular weight compound, and have completed the present invention.

Thus, the present invention relates to (A) (a) 5 to 60% by weight of styrene, (b) 5 to 50% by weight of isobornyl (meth) acrylate, and (c) 10 to 40% of a hydroxyl group-containing polymerizable unsaturated monomer. % By weight and (d) other polymerizable unsaturated monomers copolymerizable with the above components (a), (b) and (c). A monomer component comprising 0 to 80% by weight is a constituent component, and the weight average molecular weight is 2%. 2,000 or more and less than 20,000, and a hydroxyl value of 50 to
A copolymer in the range of 150 mg KOH / g, (B)
(A) 5-60% by weight of styrene, (b) 5-50% by weight of isobornyl (meth) acrylate, (c) 5-30% by weight of a hydroxyl group-containing polymerizable unsaturated monomer, and (d)
Other polymerizable unsaturated monomers copolymerizable with the above components (a), (b) and (c).
00-100,000, hydroxyl value 20-100mgK
An object of the present invention is to provide a coating composition containing a copolymer in the range of OH / g and (C) a curing agent.

Further, the present invention is characterized in that a liquid colored base paint is applied, and then the above-mentioned paint composition is applied on the base coat and dried while the base coat is in an uncured state. A method for forming a repair coating film is provided.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the coating composition of the present invention will be described in detail. The coating composition of the present invention is a coating composition containing the following copolymer (A), copolymer (B), curing agent (C) and organic solvent (D) as essential components.

Copolymer (A) In the composition of the present invention, the copolymer (A) comprises (a) styrene, (b) isobornyl (meth) acrylate,
(C) a hydroxyl group-containing polymerizable unsaturated monomer and (d) a monomer component comprising another polymerizable unsaturated monomer copolymerizable with the above components (a), (b) and (c). It is a copolymer.

In the present invention, "(meth) acrylate" means "acrylate or methacrylate". That is, the isobornyl (meth) acrylate as the component (b) means isobornyl acrylate or isobornyl methacrylate.

Examples of the hydroxyl group-containing polymerizable unsaturated monomer (c) include 2-hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, 2,3-dihydroxybutyl (meth) acrylate, and 4-hydroxybutyl. Monoesters of polyhydric alcohol and acrylic acid or methacrylic acid, such as (meth) acrylate and polyethylene glycol mono (meth) acrylate; ε-caprolactone to the monoester of polyhydric alcohol and acrylic acid or methacrylic acid Ring-opening polymerized compounds such as "Placcel FA
-1 "," Placcel FA-2 "," Placcel FA-
3 "," Placcel FA-4 "," Placcel FA-
5 "," Placcel FM-1 "," Placcel FM-
2 "," Placcel FM-3 "," Placcel FM-
And "Placcel FM-5" (both manufactured by Daicel Chemical Industries, Ltd., trade names). These can be used alone or in combination of two or more.

The other polymerizable unsaturated monomer (d) (hereinafter sometimes abbreviated as “other monomer”) can be copolymerized with the above components (a), (b) and (c). There are polymerizable unsaturated monomers other than styrene (a), isobornyl (meth) acrylate (b) and polymerizable unsaturated monomer (c).

Examples of the other monomer as the component (d) include methyl (meth) acrylate, ethyl (meth) acrylate, n-propyl (meth) acrylate, isopropyl (meth) acrylate, n-butyl (meth) acrylate, isobutyl (meth) acrylate, tert- butyl (meth) acrylate, 2-ethylhexyl acrylate, n- octyl (meth) acrylate, C _{1 to 24,} such as lauryl (meth) acrylate, tridecyl (meth) acrylate, stearyl (meth) acrylate Alkyl (meth) acrylates; carboxyl group-containing polymerizable unsaturated monomers such as acrylic acid, methacrylic acid, maleic acid, and maleic anhydride; glycidyl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth) acrylate Epoxy group-containing polymerizable unsaturated monomers such as N, N-dimethylaminoethyl (meth) acrylate, N, N-diethylaminoethyl (meth) acrylate, and N, N-dimethylaminopropyl (meth) acrylate; Meta)
Acrylate; acrylamide, methacrylamide,
N, N-dimethylaminoethyl (meth) acrylamide, N, N-diethylaminoethyl (meth) acrylamide, N, N-dimethylaminopropyl (meth) acrylamide, N-methylolacrylamide, N-methylolacrylamide methyl ether, N-methylol (Meth) acrylamide such as acrylamide butyl ether or a derivative thereof; acrylonitrile, methacrylonitrile, vinyl acetate, beoba monomer (manufactured by Shell Chemical Co., Ltd.), vinyl toluene, α-methylstyrene, and the like. These compounds can be used alone or in combination of two or more. In the present invention, “(meth) acrylamide” means acrylamide or methacrylamide.

In the composition of the present invention, the proportion of each monomer constituting the copolymer (A) is preferably within the following range based on all the constituting monomers.

(A) 5 to 60% by weight, preferably 20 to 50% by weight of styrene, (b) 5 to 50% by weight, preferably 10 to 40% by weight of isobornyl (meth) acrylate, and (c) polymerizable hydroxyl group-containing polymer. Unsaturated monomer 10-40
%, Preferably 15 to 35% by weight, (d) 0 to 80% by weight of other monomers, preferably 0 to 55% by weight.

It is preferable that the amount of styrene is in the range of 5 to 60% by weight from the viewpoint of the glossiness of the resulting coating film and the resistance to uneven return. The amount of isobornyl (meth) acrylate is preferably in the range of 5 to 50% by weight from the viewpoint of the workability of polishing the coating film, the resistance to nonuniformity in return, and the like. The amount of the hydroxyl group-containing polymerizable unsaturated monomer is 10 to 40.
It is preferable that the content is within the range of% by weight from the viewpoints of curability, coating film hardness, finish of the coating film, and the like.

The copolymer (A) has a weight average molecular weight of at least 2,000 and less than 20,000, preferably at least 5,000.
Within the range of 000 to 15,000, it is preferable from the viewpoint of the finish of the coating film and the resistance to non-uniformity of return, and the hydroxyl value is 50 to 150 mgKOH / g, preferably 80 to 1 mgKOH / g.
It is preferable that it is within the range of 30 mgKOH / g from the viewpoints of curability, coating film hardness, finish of the coating film, and the like.
It is preferred that the glass transition temperature is in the range of 20-70C.

In the present invention, the weight average molecular weight is measured by gel permeation chromatography (GPC) using a standard polystyrene calibration curve, and the glass transition temperature (Tg) is determined by differential thermal analysis (DTA). Things.

The polymerization method for obtaining the copolymer (A) by polymerizing the above monomer component is not particularly limited, and is a polymerization method known per se, for example, a bulk polymerization method in the presence of a radical polymerization initiator. Among them, a solution polymerization method can be preferably used, such as a polymerization method, a solution polymerization method, a bulk-suspension two-stage polymerization method in which suspension polymerization is performed after bulk polymerization.

Examples of the radical polymerization initiator include ketone peroxides such as cyclohexanone peroxide, 3,3,5-trimethylcyclohexanone peroxide and methylcyclohexanone peroxide; 1,1-bis (tert-butylperoxy). ) -3,
3,5-trimethylcyclohexane, 1,1-bis (te
rt-butylperoxy) cyclohexane, n-butyl-
4,4-bis (tert-butylperoxy) valerate,
2,2-bis (4,4-ditert-butylperoxycyclohexyl) propane, 2,2-bis (4,4-ditert
-Amyl peroxycyclohexyl) propane, 2,2
-Bis (4,4-ditert-hexylperoxycyclohexyl) propane, 2,2-bis (4,4-ditert-octylperoxycyclohexyl) propane, 2,2-
Peroxyketals such as bis (4,4-dicumylperoxycyclohexyl) propane; hydroperoxides such as cumene hydroperoxide and 2,5-dimethylhexane-2,5-dihydroperoxide;
1,3-bis (tert-butylperoxy-m-isopropyl) benzene, 2,5-dimethyl-2,5-di (tert
Dibutyl peroxides such as -butylperoxy) hexane, diisopropylbenzene peroxide and tert-butylcumyl peroxide; diacyl peroxides such as decanoyl peroxide, lauroyl peroxide, benzoyl peroxide and 2,4-dichlorobenzoyl peroxide Oxides; Peroxycarbonates such as bis (tert-butylcyclohexyl) peroxydicarbonate; Peroxyesters such as tert-butylperoxybenzoate and 2,5-dimethyl-2,5-di (benzoylperoxy) hexane And organic azo polymerization initiators such as 2,2'-azobisisobutyronitrile and 1,1-azobis (cyclohexane-1-carbonitrile).

The polymerization method by the solution polymerization method includes:
For example, there can be mentioned a method in which the monomer mixture is dissolved or dispersed in an organic solvent, and the mixture is heated with stirring at a temperature of usually about 80 ° C. to 200 ° C. in the presence of the radical polymerization initiator. The reaction time is usually 1 to 24
Time is appropriate.

Examples of the organic solvent include hydrocarbon solvents such as heptane, toluene, xylene, octane and mineral spirit; esters such as ethyl acetate, n-butyl acetate, isobutyl acetate, ethylene glycol monomethyl ether acetate and diethylene glycol monobutyl ether acetate. Ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone and cyclohexanone; alcohol solvents such as methanol, ethanol, isopropanol, n-butanol, sec-butanol and isobutanol; n-butyl ether, dioxane, ethylene glycol monomethyl Ethers, ethers such as ethylene glycol monoethyl ether and the like; Swazole 310, Swazole 1000, Swazole 1500 (or more, Both are manufactured by Cosmo Oil), SH
ELLSOL A (Shellsol A, manufactured by Shell Chemical Company)
And other aromatic petroleum solvents. These organic solvents can be used alone or in combination of two or more.

Copolymer (B) The copolymer (B) in the composition of the present invention comprises (a) styrene, (b) isobornyl (meth) acrylate, (c) a hydroxyl group-containing polymerizable unsaturated monomer and (D)
It is a hydroxyl group-containing copolymer containing a monomer component composed of other monomers as a constituent component.

The hydroxyl group-containing polymerizable unsaturated monomer (c) and the other monomer (d) are respectively a constituent monomer component of the copolymer (A) and the hydroxyl group-containing polymerizable unsaturated monomer (c) and the other monomer (d). And the same monomers as in (1).

In the composition of the present invention, the mixing ratio of each monomer constituting the copolymer (B) is preferably within the following range based on all the constituting monomers.

(A) 5 to 60% by weight, preferably 20 to 50% by weight of styrene, (b) 5 to 50% by weight, preferably 10 to 40% by weight of isobornyl (meth) acrylate, and (c) polymerizable hydroxyl group-containing polymer. 5 to 30% by weight of unsaturated monomer, preferably 10 to 25% by weight; (d) 0 to 80% by weight of other monomers, preferably 0 to 60% by weight.

The amount of styrene is preferably in the range of 5 to 60% by weight from the viewpoints of the glossiness of the obtained coating film and the resistance to nonuniformity in return. It is preferable that the amount of isobornyl (meth) acrylate is in the range of 5 to 50% by weight from the viewpoint of the workability of polishing the coating film, the resistance to uneven return, and the like.
The amount of the hydroxyl group-containing polymerizable unsaturated monomer is 5 to 30% by weight.
Is preferably from the viewpoints of curability, coating film hardness, coating film finish, and the like.

Further, the copolymer (B) has a weight average molecular weight of 20,000 to 100,000, preferably 220,000.
It is suitable from the viewpoints of finish of the coating film, resistance to uneven return, sagging resistance and the like, and the hydroxyl value is in the range of from 00 to 80,000, preferably from 20 to 100 mgKOH / g, more preferably from 40 to 90 mgKOH / g. Is preferable from the viewpoints of curability, coating film hardness, finish of the coating film and the like, and the glass transition temperature is preferably in the range of 20 to 70 ° C.

The polymerization method for obtaining the copolymer (B) by polymerizing the monomer components can be the same polymerization method as the polymerization method for obtaining the copolymer (A).

The above copolymer (A) and the above copolymer (B)
Weight average molecular weight, the copolymer (B)
Is preferably 5,000 or more larger than the copolymer (A), and more preferably 10,000 or more from the viewpoints of finishability, sagging resistance and the like of the coating film.
The copolymer (A) is 0 to 60 mg KO more than the copolymer (B).
H / g range is large, furthermore, 10 to 40 mg KO
It is preferable that the range of H / g is large from the viewpoint of finishability of the coating film and hardness of the coating film.

Curing Agent (C) In the present invention, the curing agent which is the component (C) can react with the hydroxyl groups in the copolymers (A) and (B) to form a cured coating film. For example, polyisocyanates, blocked polyisocyanate compounds, amino resins and the like can be mentioned. These can be used alone or in combination of two or more.

Examples of the polyisocyanate include aliphatic diisocyanates such as lysine diisocyanate, hexamethylene diisocyanate, and trimethylhexane diisocyanate; hydrogenated xylylene diisocyanate, isophorone diisocyanate, and methylcyclohexane-2,4 (or 2,6)-. Cycloaliphatic diisocyanates such as diisocyanate, 4,4'-methylenebis (cyclohexyl isocyanate) and 1,3- (isocyanatomethyl) cyclohexane; aromatic diisocyanates such as tolylene diisocyanate, xylylene diisocyanate and diphenylmethane diisocyanate An organic polyisocyanate itself such as a trivalent or higher polyisocyanate such as lysine triisocyanate or the like; Each organic polyisocyanates with polyhydric alcohol, an adduct of low molecular weight polyester resin or water, etc., or cyclic polymer of the organic diisocyanate comrades such described above (e.g., isocyanurates),
Biuret type adducts and the like can be mentioned. Of these,
Of these, isocyanurate of hexamethylene diisocyanate is preferred. These can be used alone or in combination of two or more.

When the composition of the present invention is used as a coating material for repair or the like, which is a low-temperature curing coating material at room temperature or about 100 ° C. or lower, it is preferable to use the above polyisocyanate as a curing agent (C). In the case of baking conditions exceeding ℃, a blocked polyisocyanate compound or an amino resin can be suitably used in addition to the polyisocyanate.

The blocked polyisocyanate compound is obtained by blocking the isocyanate group of the polyisocyanate with a blocking agent. Examples of the blocking agent include phenols such as phenol, cresol and xylenol; ε-caprolactam;
Lactams such as valerolactam, γ-butyrolactam, β-propiolactam; methanol, ethanol, n-
Or i-propyl alcohol, n-, i- or t-butyl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, propylene glycol monomethyl ether,
Alcohols such as benzyl alcohol; oximes such as formamidoxime, acetoaldoxime, acetoxime, methyl ethyl ketoxime, diacetyl monooxime, benzophenone oxime, cyclohexane oxime; dimethyl malonate, diethyl malonate, ethyl acetoacetate, ethyl acetoacetate, methyl acetoacetate, acetylacetone, etc. A blocking agent such as an active methylene type can be suitably used. The isocyanate group of the polyisocyanate can be easily blocked by mixing the polyisocyanate with the blocking agent.

The melamine resin usable as the curing agent (C) includes a methylolated melamine resin obtained by reacting melamine with an aldehyde. Examples of the aldehyde include formaldehyde, paraformaldehyde, acetaldehyde, and benzaldehyde. In addition, this methylolated melamine resin may be used alone or
Those etherified with more than one kind of alcohol can also be used. Examples of the alcohol used for the etherification include methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, 2-ethylbutanol,
Monohydric alcohols such as 2-ethylhexanol are exemplified. Of these, it is preferable melamine resins obtained by etherifying at least part of the methylol groups of inter alia methylolated melamine resin with monohydric alcohol C _{1 to 4.}

The coating composition of the present invention contains the copolymer (A), the copolymer (B) and the curing agent (C) as essential components. The mixing ratio of the component (A) to the component (B) is usually 95% by weight of the solid content of (A) / (B).
/ 5 to 50/50, preferably 90/10 to 60/40
Is suitably within the range.

When the curing agent (C) is a polyisocyanate or a blocked polyisocyanate compound, a free or blocked isocyanate group (NC
O) is usually 0.2 to 2.0, preferably in an equivalent ratio of NCO / OH to the hydroxyl group (OH) in the total of the copolymer (A) and the copolymer (B). Is 0.5 to 1.5
It is appropriate to be within the range as follows.

When the curing agent (C) is a polyisocyanate, when the copolymer (A) and / or the copolymer (B) and the polyisocyanate are mixed, the reaction between the two occurs. It is preferable to form a two-pack type coating material in which the copolymer and the polyisocyanate are separated, and to mix them at the time of use.

When the curing agent (C) is a melamine resin, the mixing ratio of the sum of the copolymer (A) and the copolymer (B) and the curing agent (C) is based on the weight ratio of the solid content. Then, [(A)
And (B)] / (C) is 90/10 to 60/40
Is suitably within the range.

The coating composition of the present invention comprises the above (A) and (B)
And component (C) as an essential component, and if necessary,
Organic solvents, curing catalysts, pigments; UV absorbers, coating surface adjusters, antioxidants, fluidity adjusters, waxes and the like can be appropriately contained.

The coating composition of the present invention is usually an organic solvent type coating composition. In this case, an organic solvent which can dissolve or disperse each component of the coating can be used.
The above-mentioned organic solvents listed as usable when solution-polymerizing the copolymer (A) can be used as they are,
Further, various similar organic solvents may be appropriately added.

The above-mentioned curing catalyst optionally added to the composition of the present invention promotes the curing reaction of the composition of the present invention. For example, the curing agent (C) is a blocked polyisocyanate compound. In such a case, a curing catalyst that promotes the dissociation of the blocking agent of the blocked polyisocyanate compound as a curing agent is preferable, and as a suitable curing catalyst,
For example, tin octylate, dibutyltin di (2-ethylhexanoate), dioctyltin di (2-ethylhexanoate), dioctyltin diacetate, dibutyltin dilaurate, dibutyltin oxide, dioctyltin oxide, 2-ethyl An organic metal catalyst such as lead hexanoate may be used.

When the curing agent (C) contains a melamine resin, especially a low-molecular-weight melamine resin of methyl etherification or a mixed etherification of methyl ether and butyl ether, a sulfonic acid compound or a sulfonic acid compound is used as a curing catalyst. Amine neutralized products are preferably used. Representative examples of the sulfonic acid compound include p-toluenesulfonic acid,
Dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, dinonylnaphthalenedisulfonic acid and the like can be mentioned. The amine in the amine neutralized product of the sulfonic acid compound may be any of a primary amine, a secondary amine, and a tertiary amine. Among these, from the viewpoint of the stability of the paint, the reaction promoting effect, and the physical properties of the obtained coating film,
An amine neutralized product of p-toluenesulfonic acid and / or an amine neutralized product of dodecylbenzenesulfonic acid are preferred.

The coating composition of the present invention is swollen by a polar solvent such as for repairing automotive coatings and for repairing architectural exterior coatings.
When coating on easily soluble coatings, plastic materials with poor solvent resistance, or when applying wet-on-wet on uncured colored base coatings,
It is preferable to reduce or eliminate the use amount of the polar solvent in terms of preventing lifting of the lower layer coating film, preventing generation of solvent cracks in the plastic material, and preventing return unevenness of the colored base coating film. Examples of low-polar or non-polar solvents that are not polar solvents include hydrocarbon solvents, ether solvents, and aromatic petroleum solvents.

The coating composition of the present invention comprises iron, aluminum, brass, copper plate, stainless steel plate, tin plate, galvanized steel plate, alloyed zinc (Zn-Al, Zn-Ni, Zn-
Metals such as plated steel sheets, such as Fe); surface-treated metals obtained by subjecting these metal surfaces to chemical conversion treatments such as phosphate treatment and chromate treatment; directly or directly on materials to be coated such as plastic, wood, concrete, and mortar The material to be coated can be applied to the cured coating surface or the uncured coating surface of a coating material obtained by applying a primer and / or a middle coating and / or a top coating base, and by baking, has a high gloss and excellent polishing finish. A coating film can be formed, and a highly finished coating film having excellent resistance to return unevenness and sag resistance can be formed.

The coating composition of the present invention may be a colored coating composition or a clear coating composition. The coating composition of the present invention can form a coating film having high gloss and excellent abrasiveness, and has excellent resistance to return unevenness and resistance to sag, and can form a coating film having a high finish. By using the clear coating for repair, the effects of the present invention can be maximized.

When the coating composition of the present invention is used as a clearing material for repair, a water-based or solvent-type liquid colored base coating material is usually applied to the repaired part whose base has been adjusted as necessary. In a state where the coating film is in an uncured state, a repair coating can be suitably formed by applying a repair clear on the base coating film and drying it. After applying the colored base paint, after curing the base coat, a clear for repair may be applied on the base coat and dried.

The coating thickness of the coating composition of the present invention is not particularly limited, but usually the cured coating thickness is 3 to 60 μm.
m, preferably about 5 to 50 μm, and drying conditions are not particularly limited as long as the coating film is cured, and are usually in the range of room temperature to 120 ° C. for 1 minute to 10 days. Is preferred.

[0050]

The present invention will now be described more specifically with reference to examples and comparative examples. Hereinafter, “parts” and “%” are based on weight unless otherwise specified.

Production of Hydroxyl-Containing Copolymer Production Example 1 60 parts of xylene was charged into a reaction vessel equipped with a stirrer, thermometer, reflux condenser, thermostat and dropping pump, and the temperature was raised to 125 ° C. while stirring. Then, 106.5 parts of a mixture of a monomer and a polymerization initiator shown in Table 1 below was dropped at a constant rate over 3 hours using a dropping pump. After completion of the dropwise addition, the mixture was aged at the same temperature for 2 hours to complete the reaction. The obtained hydroxyl group-containing copolymer solution was a uniform transparent solution having a nonvolatile content of 60% and a Gardner foam viscosity UV. The copolymer has a weight average molecular weight of about 9,000 and a hydroxyl value of 118.
mg KOH / g.

Production Examples 2 to 11 The same procedure as in Production Example 1 was carried out except that the amount of xylene charged, the reaction temperature, and the mixture of the monomer and the polymerization initiator were as shown in Table 1 below. A polymer solution was obtained. Table 1 shows the properties of the obtained copolymer solutions and copolymers.
Shown in

[0053]

[Table 1]

Examples 1 to 5 and Comparative Examples 1 to 4 Using the hydroxyl group-containing copolymer solutions obtained in the above Production Examples,
A clear paint was prepared according to the formulation shown in Table 2 below.

(Note) in Table 2 has the following meaning.

(* 1) Duranate TPA100: an isocyanurate of hexamethylene diisocyanate, manufactured by Asahi Kasei Corporation, NCO content 23.1%, nonvolatile content 100
%.

Preparation of Test Coated Plate The obtained clear paint was treated with a mixed solvent having a composition of xylene / butyl acetate / Shellsol A (Note 1) = 60/20/20 (weight ratio) for about 14 seconds (Ford Cup # 4, 25
° C) to obtain a viscous clear paint. "Retan PG2K No.123" (Note 2) is applied at 20 ° C to the process coated plate on which the clear paint for new vehicles is baked.
After setting for 10 minutes, the viscous clear paint was spray-coated thereon so that the dry film thickness of the clear coating film became about 40 μm, and dried at 60 ° C. for 30 minutes to obtain a test coated plate.

(Note 1) Shell Sol A: trade name, aromatic petroleum solvent manufactured by Shell Chemical Company. (Note 2) Rethane PG2K No. 123: Acrylic / urethane two-pack type colored base paint, metallic color, manufactured by Kansai Paint Co., Ltd.

Using the obtained test coated plate, each test of the finished property, the resistance to non-uniformity in return, the pencil hardness and the polished finished property of the coating film was carried out according to the following test methods. In addition, a test of the sagging limit film thickness was also performed. The results of these tests are shown in Table 2 below.

Test Method Finishing property of coating film: The glossiness, smoothness and transparency of the coating film of the test coated plate were visually judged and evaluated according to the following criteria (metallic return unevenness was evaluated separately).

：: good Δ: slightly bad ×: bad

Nonuniformity in return resistance: The unevenness of the metallic appearance of the coating film of the test coated plate was visually evaluated. ：: Good metallic appearance, good return unevenness resistance Δ: Slight unevenness in the metallic appearance, slightly poor return unevenness ×: Remarkable unevenness in the metallic appearance, poor poor return unevenness .

Pencil hardness: The test coated plate dried at 60 ° C. for 30 minutes is further left for 7 days in a constant temperature / humidity room at a temperature of 20 ° C. and a humidity of 60%, and then JIS K5400.
A pencil scratch test specified in 8.4.2 (1990) was performed, and evaluation was performed by a tear method.

Polishing finish: The test coated plate dried at 60 ° C. for 30 minutes is further left in a constant temperature and humidity room at a temperature of 20 ° C. and a humidity of 60% for 2 hours, and then finely polished on the coating surface of the test coated plate. After applying the compound to a towel buff and polishing for 2 minutes to polish the coating,
The scratches on the coating film surface and the finished gloss were visually evaluated according to the following criteria. ：: almost no scratches and good glossiness Δ: considerably scratches and considerably reduced glossiness ×: many scratches and little glossiness.

Sag limit film thickness: The clear paint having a viscosity adjusted for about 14 seconds (Ford Cup # 4, 25 ° C.) is applied to the process coated plate on which the clear paint for a new car has been applied and baked. And the film thickness (dry film thickness) at which sagging occurs was indicated.

[0066]

[Table 2]

[0067]

EFFECT OF THE INVENTION The coating composition of the present invention can form a coating film having high gloss and excellent abrasion properties, and can form a coating film having excellent return unevenness resistance and sagging resistance and a high finish. It can be suitably used as a repair paint, especially as a clear paint for repair.

A method for forming a repair coating film according to the present invention, in which a liquid colored base coating material is applied, and then the base coating film is coated with the coating composition of the present invention and dried in an uncured state. This makes it possible to form a highly finished coating film having high gloss, excellent polishing properties, good return unevenness resistance, and excellent sag resistance. In this case, even when the colored base coating is a metallic base coating, a highly finished coating film having a good metallic appearance can be formed since the anti-return unevenness is excellent.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) C09D 133/14 C09D 133/14 // C08G 18/62 C08G 18/62 (72) Inventor Yoshizumi Matsuno Kanagawa 4-17-1, Higashi-Hachiman, Hiratsuka-shi, Kanagawa F-term (reference) in Kansai Paint Co., Ltd. 4D075 CB13 DA27 DB02 DC12 EA43 EB22 EB52 EB55 EC11 4J034 BA03 BA05 DA01 DJ09 DP13 DP18 HA01 HA07 HB08 HC03 HC12 HC17 HC22 HC35 HC46 HC52 HC64 HC67 HC71 HC73 HD03 HD04 HD05 HD12 QA02 QA03 RA07 4J038 CC061 CG141 CH071 CH121 DG262 GA03 KA03 KA08 MA14 NA01

Claims (6)

[Claims] (A) (a) 5 to 60% by weight of styrene, (b) 5 to 50% by weight of isobornyl (meth) acrylate, (c) 10 to 40% by weight of a hydroxyl group-containing polymerizable unsaturated monomer, and (d) ) Other polymerizable unsaturated monomers copolymerizable with the above components (a), (b) and (c). A monomer component comprising 0 to 80% by weight as a component, and having a weight average molecular weight of 2,000 or more, And a copolymer having a hydroxyl value in the range of 50 to 150 mgKOH / g, (B) (a) 5 to 60% by weight of styrene, and (b) 5 to 50% by weight of isobornyl (meth) acrylate. %, (C) 5 to 30% by weight of a hydroxyl group-containing polymerizable unsaturated monomer and (d) 0 to 85% by weight of another polymerizable unsaturated monomer copolymerizable with the above components (a), (b) and (c). Consisting of% The monomer component is a component, and the weight average molecular weight is 2
0000-100,000, hydroxyl value 20-100
A coating composition comprising a copolymer in the range of mgKOH / g and (C) a curing agent. 2. A mixing ratio of the copolymer (A) and the copolymer (B) in a solid content ratio of (A) / (B),
The coating composition according to claim 1, wherein the composition is in the range of 95/5 to 50/50. 3. The coating composition according to claim 1, wherein the curing agent (C) is a polyisocyanate. 4. The amount of the hydroxyl group (O) in the total amount of the copolymer (A) and the copolymer (B) is as follows.
H), the isocyanato group (NC) in the curing agent (C)
The coating composition according to claim 3, wherein O) is in a range of 0.2 to 2.0 in terms of an equivalent ratio of NCO / OH. 5. The method according to claim 1, wherein a liquid colored base paint is applied, and then the paint composition according to claim 1 is applied and dried on the base coat in an uncured state. Repair coating film forming method. 6. The method according to claim 5, wherein the liquid colored base paint is a liquid metallic base paint containing a glitter pigment.