JPH08259667A - Curable resin composition, coating composition and formation of coating film - Google Patents

Abstract

PURPOSE: To obtain a curable resin composition containing different kinds of specific polycarboxylic acids and a polyepoxide, capable of forming coating films excellent in acidic rain resistance and appearance, and useful for high solid coatings, etc. CONSTITUTION: This composition comprises (A) an acrylic polycarboxylic acid having two or more carboxyl groups in the molecule, an acid value of 5-300 (mg KOH/g) and a number-average mol. wt. (Mn) of 500-8000, (B) a polycarboxylic acid having an acid value of 50-350, a Mn of 400-3500, and a weight-average mol. wt./Mn ratio of <=1.8, and obtained by reacting an acid anhydride with a polyesterpolyol having three or more OH groups, and (C) a polyepoxide having an epoxy equivalent of 50-700 and a Mn of 200-10000 e.g. the copolymer of a compound of formula I [R is H, CH3 ; X is a compound of formula II (Y is a 2-8C alkylene, etc.; m is 3-7; q is 0-4), etc.,] with an epoxy group-containing ethylenic unsaturated compound}, wherein the contents of the components A, B and C are 10-70wt.%, 5-70wt.% and 10-80wt.%, respectively, based on the whole amount of the composition.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable resin composition suitable for use as a top coat paint and a coil coating paint for automobiles.

[0002]

2. Description of the Related Art It is common to use a combination of a hydroxyl group-containing polymer and a melamine resin curing agent in a binder used as a top coating for automobiles. However, a cured coating obtained by using such a melamine resin as a curing agent generally has poor acid resistance. Therefore, such a coating is particularly susceptible to deterioration due to acid rain, which has been a problem in recent years, and causes a defect in appearance.

The poor acid resistance of the coating film obtained by using a melamine resin as a curing agent is believed to be due to the triazine nucleus in the melamine resin. Therefore, as long as the melamine resin is used as a curing agent, the drawback of poor acid resistance cannot be solved.

[0004] JP-A-2-45577 and JP-A-3-287650 propose a novel coating composition which does not use a melamine resin. This coating composition has good acid resistance because it has an ester bond formed by reacting an acid group and an epoxy group as a crosslinking point.

However, in this curing system, since the functional group concentration is high and the viscosity is high, it is difficult to form a high solid content high solid type paint, and it is necessary to use a large amount of solvent. On the other hand, in recent years, in order to reduce adverse effects on the environment, there is a demand for high solid paints that release a small amount of solvent into the atmosphere.

Japanese Unexamined Patent Publication (Kokai) No. 6-166741 discloses a high solid coating composition using a silicone polymer. However, in these documents, in order to introduce a hydroxyl functional silicone polymer into a coating composition, it is reacted with an acid anhydride group-containing compound to impart acid functionality. As a result, the amount of functional groups cannot be increased, the resin Tg is lowered, and there is a drawback that the Tg of the coating film cannot be increased.

On the other hand, Japanese Patent Publication No. 6-41575 discloses a high solid coating composition containing (a) polyepoxide and (b) polyester polycarboxylic acid. However, it cannot be said that the solid content of this coating composition is sufficiently high from the viewpoint of not adversely affecting the environment, and the formed coating film has poor acid resistance.

[0008]

SUMMARY OF THE INVENTION The present invention is to solve the above-mentioned conventional problems, and an object thereof is to obtain a high solid content which forms a film excellent in acid rain resistance, scratch resistance and appearance. It is intended to provide a curable resin composition, a high solid coating composition, and a coating film forming method using these.

[0009]

The present invention provides (a) an average of 2 or more carboxyl groups in one molecule and an acid value of 5 to 300 mgKOH / g.
And 10 to 70% by weight of an acrylic polycarboxylic acid having a number average molecular weight of 500 to 8000; (b) an acid value of 50 to 50 obtained by reacting a polyester polyol having three or more hydroxyl groups with an acid anhydride group-containing compound. 350 mg KOH / g (solid content), number average molecular weight 400-3500 and weight average molecular weight / number average molecular weight
High solids curable resin composition containing 5 to 70% by weight of a polyester polycarboxylic acid having 1.8 or less; and (c) 10 to 80% by weight of an epoxy equivalent of 50 to 700 and a polyepoxide having a number average molecular weight of 200 to 10,000. (However, component (a) ~
The compounding amount of (c) is based on the weight of the total solid content in the curable resin composition. ) Is provided, thereby achieving the above object.

The acrylic polycarboxylic acid (a) used in the curable resin composition of the present invention has an average of two or more carboxyl groups in one molecule, an acid value of 5 to 300 mgKOH / g, preferably 25 to.
An acrylic polycarboxylic acid having 250 mgKOH / g, more preferably 50 to 200 mgKOH / g and a number average molecular weight of 500 to 8000, preferably 800 to 6000, and more preferably 1500 to 4000.

This acrylic polycarboxylic acid comprises 5 to 80% by weight of a carboxyl group-containing ethylenically unsaturated monomer.
It can be obtained by copolymerizing 20 to 95% by weight of an ethylenically unsaturated monomer having no carboxyl group with a known method. The copolymerization is carried out, for example, by adding an azo-based initiator or a peroxide-based initiator as a radical polymerization initiator to a total amount of 100 parts by weight of the ethylenically unsaturated monomer in an amount of 0.
Used in an amount of 5 to 20 parts by weight, the polymerization temperature is 80 to 200.
The polymerization can be carried out at normal pressure or under pressure at a temperature of 3 ° C for 3 to 10 hours. At that time, a chain transfer agent, an anti-coloring agent or the like may be added.

Specific examples of the carboxyl group-containing ethylenically unsaturated monomer include, for example, acrylic acid, methacrylic acid, itaconic acid, maleic acid, and adducts thereof with ε-caprolactone (for example, "Aronix manufactured by Toagosei Kagaku Co., Ltd."). M-5300 ") etc., an adduct of an ethylenically unsaturated monomer having a hydroxyl group represented by formula (I) and an acid anhydride group-containing compound, and an addition of an acid anhydride group-containing ethylenically unsaturated monomer and a monoalcohol. Things can be mentioned. These can be used alone or in combination of two or more.

The acid anhydride group-containing compound has a room temperature to 150 ° C.
Carboxy functionality is provided by a half-esterification reaction with hydroxyl groups under normal reaction conditions such as atmospheric pressure. Here, a ring having 4 to 12 carbon atoms, particularly 8 to 10 carbon atoms
It is preferable to use an acid anhydride group-containing compound having an (unsaturated or saturated) group. This is because when such a compound is used, the compatibility of the obtained resin becomes good. Specific examples of preferred acid anhydride group-containing compounds include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, trimellitic anhydride, succinic anhydride and the like.

Specific examples of the acid anhydride group-containing ethylenically unsaturated monomer used here include itaconic anhydride, maleic anhydride and citraconic anhydride.

Specific examples of the monoalcohol used here include methanol, ethanol, n-propanol, i-propanol, n-butanol, i-butanol, t-butanol and n-butanol.
Examples thereof include hexyl alcohol, lauryl alcohol, methyl cellosolve, ethyl cellosolve, methoxypropanol, ethoxypropanol, furfuryl alcohol, dimethylaminoethanol, diethylaminoethanol, acetol, allyl alcohol and propargyl alcohol.

Specific examples of the ethylenically unsaturated monomer having no carboxyl group include styrene, α-methylstyrene, pt-butylstyrene and (meth) acrylic acid ester.
(For example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, (meth) acrylic acid
n-, i-, and t-butyl, 2-ethylhexyl (meth) acrylate and lauryl (meth) acrylate, cyclohexyl (meth) acrylate, isobornyl (meth) acrylate, etc.), VeoVa-9 manufactured by Shell Co. And VeoVa-10 and the like. When styrene and styrene derivatives are used as the ethylenically unsaturated monomer having no carboxyl group, it is preferably used in an amount of 5 to 40% by weight.

Preferably, as the acrylic polycarboxylic acid (a) of the curable resin composition of the present invention, an acrylic polycarboxylic acid (a) having a carboxyl group and a carboxylic ester group on adjacent carbons is used. . This is because the acid resistance of the obtained coating film is improved. Acrylic polycarboxylic acid having carboxyl group and carboxylic acid ester group
(a) can be obtained, for example, by reacting an acrylic polyanhydride (a) (i) with a monoalcohol (a) (ii).

The acrylic polyanhydride (a) (i) is an acid anhydride group-containing ethylenically unsaturated monomer (a) (i) (1) in an amount of 15 to 40% by weight, preferably 15 to 35% by weight. It is obtained by copolymerizing with 60 to 85% by weight, preferably 65 to 85% by weight of ethylenically unsaturated monomer (a) (i) (2) having no acid anhydride group. Acid anhydride group-containing ethylenically unsaturated monomer (a) (i)
If the amount of (1) is less than 15% by weight, the curability will be insufficient, and if it exceeds 40% by weight, the coating film obtained will be too hard and brittle and the weather resistance will be insufficient. Specific examples of the acid anhydride group-containing ethylenically unsaturated monomer (a) (i) (1) include those already described.

The ethylenically unsaturated monomer (a) (i) (2) having no acid anhydride group is not particularly limited as long as it does not adversely affect the acid anhydride group, and an ethylenically unsaturated bond A monomer having 3 to 15 carbon atoms, particularly 3 to 12 carbon atoms is preferable.

Ethylenically unsaturated monomer having no acid anhydride group by mixing two or more kinds of ethylenically unsaturated monomers
It can also be used as (a) (i) (2). This is because it is effective in improving the compatibility between the resins. Specifically, the above-mentioned monomers may be mentioned as the ethylenically unsaturated monomer having no carboxyl group.

Monomers having a carboxyl group such as acrylic acid, methacrylic acid, itaconic acid and maleic acid are also ethylenically unsaturated monomers having no acid anhydride group.
It can be used as (a) (i) (2). Among them, an adduct of these and ε-caprolactone (for example, Aronix M-530
When a long-chain carboxylic acid monomer having a spacer portion having about 5 to 20 carbon atoms between an ethylenically unsaturated group and a carboxyl group such as 0) is used, scratch resistance of the coating film is improved, preferable.

For example, the hydroxyl group-containing ethylenically unsaturated monomer and the acid anhydride group-containing compound have a molar ratio of the hydroxyl group and the acid anhydride group of 1 / 0.5 to 1 / 1.0, preferably 1 / 0.8 to 1 / 1.0. A carboxyl group-containing ethylenically unsaturated monomer obtained by carrying out a half-esterification reaction in an amount of
It can be used as (a) (i) (2). If this molar ratio is 1 / 0.5 or more, the polymer viscosity becomes high and the workability becomes poor. 1 / 1.0
When the amount is less than the above, excess acid anhydride group-containing compound remains, and the water resistance of the coating film decreases.

The hydroxyl group-containing ethylenically unsaturated monomer used herein preferably has 5 to 23 carbon atoms, and 5 to 23 carbon atoms.
More preferably, it is 13. This is because if the chain length is too short, the flexibility in the vicinity of the cross-linking point is lost and the chain becomes too hard, and if it is too long, the molecular weight between cross-linking points becomes too large. In general, the expression [In the formula, R represents a hydrogen atom or a methyl group, and X represents a formula. (In the formula, Y is a linear or branched alkylene group having 2 to 8 carbon atoms, m is an integer of 3 to 7, and q is an integer of 0 to 4.), or ,formula (In the formula, R is a hydrogen atom or a methyl group, and n is 2 to 50.
Is an integer. ) Is an organic chain. ] A hydroxyl group-containing ethylenically unsaturated monomer having a structure shown by Specifically, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, (meth) acrylic acid Compounds such as 6-hydroxyhexyl and their reaction with ε-caprolactone and (meth) acrylic acid with a large excess of diol (eg 1,4 butanediol, 1,6 hexanediol, polyethylene glycol, polypropylene glycol) The compound which can be prepared by esterifying is mentioned.

Such compounds are commercially available, for example, 4-hydroxybutyl acrylate "4HBA" and 4-hydroxybutyl methacrylate "4HBM" manufactured by Mitsubishi Chemical Corporation.
Examples thereof include "Plaxel FM1" and "Plaxel FA1" manufactured by Daicel Chemical Industries, Ltd. As a propylene oxide-based monomer, "Blenmer PP-" manufactured by NOF CORPORATION
Examples of "1000", "Blemmer PP-800" and ethylene oxide-based monomers include "Blemmer PE-90".

Specific examples of the acid anhydride group-containing compound used here include phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, 4-methylhexahydrophthalic anhydride, trimellitic anhydride and succinic anhydride. Is mentioned.

The half-esterification reaction between the hydroxyl group-containing ethylenically unsaturated monomer and the acid anhydride group-containing compound is carried out at a temperature of room temperature to 150 ° C. according to a conventional method.

Acid anhydride group-containing ethylenically unsaturated monomer
The copolymerization of (a) (i) (1) and an ethylenically unsaturated monomer having no acid anhydride group (a) (i) (2) is carried out by a known method such as solution polymerization such as radical polymerization. The polymerization temperature can be 100 to 200 ° C. and the polymerization time can be 3 to 8 hours under normal pressure or pressure. As the initiator, an azo type or peroxide type initiator is preferably used.
Other additives such as chain transfer agents may also be used.

The number average molecular weight of the obtained polymer is 500 to 8
It is preferably 000, 800 to 6000, and particularly 1500 to 4000. If the number average molecular weight is more than 8,000, the compatibility between resins decreases and the appearance deteriorates. If the number average molecular weight is less than 500, the curability of the resin composition will be insufficient. The average number of the polymers obtained is at least 2, preferably 2 per molecule.
If the number of acid anhydride groups contained in one molecule having less than 15 acid anhydride groups is less than 2, the curability of the resin composition will be insufficient. If it exceeds 15, it becomes too hard and brittle, and the weather resistance is insufficient.

Then, the obtained acrylic polyanhydride
(a) (i), the acid anhydride group and the hydroxyl group in a molar ratio of 1/10 ~ 1 /
1, preferably 1/5 to 1/1, more preferably 1 / 2.0 to 1/1 by reacting with a monoalcohol (a) (ii), a carboxyl group and a carboxylic acid ester group An acrylic polycarboxylic acid (a) having is prepared. 1/10
If it is less than 1, excess alcohol is too much, causing armpits during curing, and if it exceeds 1/1, unreacted anhydride groups remain,
Storage stability becomes poor.

Monoalcohol (a) (ii) that can be used in the present invention
Preferably has 1 to 12, especially 1 to 8 carbon atoms. This is because the alcohol volatilizes during heating and is good for regenerating the acid anhydride group. Specific examples of the monoalcohol that can be suitably used include those already listed. Particularly preferred are acetol, furfuryl alcohol,
Allyl alcohol, propargyl alcohol, ethanol and methanol.

The resulting acrylic polycarboxylic acid (a) having a carboxyl group and a carboxylic acid ester group has an acid value of 5 to 300 mgKOH / g, preferably 50 to 250 mgKOH / g. If the acid value is less than 5 mgKOH / g, the curability will be insufficient and 300
If it exceeds mgKOH / g, the storage stability becomes poor, which is not preferable.

The acrylic polycarboxylic acid (a) component is used in an amount of 10 to 70 based on the total weight of solids in the curable resin composition.
% By weight, preferably 15-50% by weight, more preferably 20-
It may be added to the curable resin composition in an amount of 45% by weight. When the blending amount of the acrylic polycarboxylic acid (a) component is less than 10% by weight, the acid resistance of the resulting coating film decreases, and when it exceeds 70% by weight, the coating film becomes too hard.

The polyester polycarboxylic acid (b) used in the curable resin composition of the present invention can be obtained by half-esterifying a polyester polyol having 3 or more hydroxyl groups with an acid anhydride group-containing compound.

The term "polyester polyol" as used herein means a polyhydric alcohol having two or more ester bond chains. Further, the polyhydric alcohol means an alcohol having two or more hydroxyl groups.

The polyester polyol used here is
Reacting with an acid anhydride group containing compound provides a polyester polycarboxylic acid having more than one acid functionality per molecule and the following properties.

Generally, such a polyester polyol is prepared by condensing a low molecular weight polyhydric alcohol having at least 3 hydroxyl groups and having 3 to 16 carbon atoms with a linear aliphatic dicarboxylic acid. By introducing a linear aliphatic group into the low molecular weight polyhydric alcohol, flexibility is imparted to the obtained coating film and impact resistance is improved.

As the low molecular weight polyhydric alcohol which can be used, trimethylolpropane, trimethylolethane,
1,2,4-butanetriol, ditrimethylolpropane,
Mention may be made of pentaerythritol, dipentaerythritol, glycerin and mixtures thereof.

Dicarboxylic acids include phthalic acid, isophthalic acid, terephthalic acid, succinic acid, adipic acid, azelaic acid, sebacic acid, tetrahydrophthalic acid, hexahydrophthalic acid, maleic acid, fumaric acid and mixtures thereof. Examples include dibasic acids. In addition, succinic anhydride, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, hymic acid anhydride, trimellitic anhydride, methylcyclohexene tricarboxylic anhydride,
Acid anhydride group containing compounds such as pyromellitic dianhydride and mixtures thereof may also be used.

The polyester polyol is synthesized by a usual esterification reaction. That is, a polyester is formed by a dehydration condensation reaction between a polyhydric alcohol and a polybasic acid, or an esterification reaction due to a reaction between a polyhydric alcohol and an acid anhydride group-containing compound, and a dehydration reaction between an alkyl component. By such an operation, a polyester polyol oligomer having a relatively low molecular weight is obtained, and a high solid resin composition is provided.

Particularly preferred polyester polyols for use in the present invention are obtained by adding a lactone compound such as ε-caprolactone to a low molecular weight polyhydric alcohol to extend the chain. This is because the molecular weight distribution becomes sharp, so that the resin composition can be made more solid, and a coating film excellent in weather resistance and water resistance can be obtained.
In this case, the low molecular weight polyhydric alcohol particularly preferably used includes trimethylolpropane, ditrimethylolpropane, pentaerythritol and the like.

Since the "lactone compound" used in the present invention has an oxygen atom in the ring, it reacts with a nucleophilic reagent to open the ring,
Any cyclic compound that produces a hydroxyl group at the terminal may be used. Preferred lactone compounds have 4 to 7 carbon atoms. This is because the ring-opening addition reaction is likely to occur.

Specific examples thereof include ε-caprolactone, γ-caprolactone, γ-valerolactone, δ-valerolactone and γ-butyrolactone, with ε-caprolactone, γ-valerolactone and γ-butyrolactone being preferred. Used.

Chain extension can be carried out under the same conditions as in ordinary ring-opening addition reaction. For example, a polyester polyol having a low molecular weight polyhydric alcohol chain-extended can be obtained by reacting in a suitable solvent or without solvent at a temperature of 80 to 200 ° C. for 5 hours or less. A tin-based catalyst or the like may be used.

At that time, the molar amount of the lactone compound is 0.2 to 10 times, preferably 0.25 to 5 times, and more preferably 0.1 to the molar amount of the low molecular weight polyhydric alcohol OH group.
3 to 3 times the amount. If the molar amount of the lactone compound is less than 0.2 times the molar amount of the OH group, the resin becomes hard and the impact resistance of the coating film decreases, and if it exceeds 10 times, the hardness of the coating film decreases.

The polyester polycarboxylic acid (b) used in the curable resin composition of the present invention has an acid value of 50 to 350, preferably
100-300, more preferably 150-250 mg KOH / g (solid content) and number average molecular weight 400-3500, preferably 500-2500, more preferably 700-2000, weight average molecular weight / number average molecular weight
It has 1.8 or less, preferably 1.5 or less, more preferably 1.35 or less.

When the acid value exceeds 350, the viscosity of the resin composition becomes too high and the solid content concentration of the resin composition decreases, and when the acid value is less than 50, the curability of the resin composition becomes insufficient. If the molecular weight exceeds 3,500, the viscosity of the resin composition becomes too high and it becomes difficult to handle, leading to a decrease in the solid content concentration of the resin composition, and if the molecular weight is less than 400, the curability of the resin composition is insufficient or a coating film. Water resistance is reduced. When the weight average molecular weight / number average molecular weight exceeds 1.8, the water resistance or weather resistance of the coating film decreases.

The half-esterification reaction between the polyester polyol and the acid anhydride group-containing compound is carried out by phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride,
It can be carried out under normal reaction conditions such as room temperature to 150 ° C. and normal pressure, using an acid anhydride group-containing compound such as 4-methylhexahydrophthalic anhydride, trimellitic anhydride and succinic anhydride. However, it is not necessary to modify all the hydroxyl groups of the polyester polyol into carboxyl groups, and the hydroxyl groups may remain.

Since the polyester polycarboxylic acid having a hydroxyl group simultaneously provides a carboxyl group and a hydroxyl group on the surface of the coating film, for example, when it is recoated, it is superior to the polyester polycarboxylic acid having no hydroxyl group. This is because it provides adhesion.

In that case, the polyester polycarboxylic acid
(b) may have a hydroxyl value of 150 mgKOH / g (solid content) or less, preferably 5 to 100 mgKOH / g, and more preferably 10 to 80 mgKOH / g. If the hydroxyl value exceeds 150 mgKOH / g, the water resistance of the coating film will decrease.

Further, the polyester polycarboxylic acid having a hydroxyl group and a carboxyl group can react and bond with both the polyepoxide (c) and the acrylic polycarboxylic acid (a), as will be described later, so that a stronger coating can be obtained. A membrane can be obtained. Those having an average of 0.1 or more hydroxyl groups in one molecule are preferable.

Generally, it is desirable that the molar amount of the acid anhydride group of the compound containing an acid anhydride group is 0.2 to 1.0 times, especially 0.5 to 0.9 times the molar amount of the OH group of the polyester polyol. If the molar amount of the acid anhydride group is less than 0.2 times the molar amount of the OH group, the curability of the obtained resin composition will be insufficient.

The polyester polycarboxylic acid (b) component is
5 to 5 based on the weight of the total solid content in the curable resin composition
70% by weight, preferably 5 to 50% by weight, more preferably 10
Can be incorporated in an amount of up to 40% by weight. When the amount of the polyester polycarboxylic acid is less than 5% by weight, the solid content concentration of the obtained coating does not increase, and when it exceeds 70% by weight, the weather resistance of the obtained coating film is deteriorated.

The polyepoxide (c) used in the curable resin composition of the present invention is a compound having an average of 2 or more epoxy groups in one molecule, preferably 2-10, more preferably 3-8. .

Examples thereof include glycidyl ethers of polyhydric alcohols and glycidyl esters of polybasic acids. Examples of these include glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether,
Examples thereof include sorbitol hexaglycidyl ether and hexahydrophthalic acid diglycidyl ester.

The number average molecular weight of the obtained polyepoxide is
200-10,000, preferably 500-8000, more preferably 800
~ 5000. When the number average molecular weight is less than 200, the curability of the coating film obtained is reduced, and when it exceeds 10,000, the solid content of the obtained coating composition is reduced. The epoxy equivalent is 50 to 700,
It is preferably 80 to 600, more preferably 100 to 500.
When the epoxy equivalent is larger than the above upper limit, the curability of the resin composition becomes insufficient. Also, if it is less than the lower limit, it becomes too hard and the coating film becomes brittle, which is not preferable.

The polyepoxide preferably used in the present invention is an epoxy group-containing ethylenically unsaturated monomer 10 to 60.
% By weight, preferably 15 to 50% by weight and 40 to 90% by weight of ethylenically unsaturated monomers without epoxy groups, preferably
It is an acrylic polyepoxide obtained by copolymerizing 10 to 60% by weight. If the epoxy group-containing ethylenically unsaturated monomer is 10% by weight or less, the curability is insufficient,
If it exceeds 60% by weight, it becomes too hard and the weather resistance becomes insufficient.

Examples of the epoxy group-containing ethylenically unsaturated monomer include glycidyl (meth) acrylate and β
-Methylglycidyl (meth) acrylate, 3,4-epoxycyclohexanyl (meth) acrylate and the like can be mentioned. Glycidyl (meth) acrylate is preferably used in order to prepare a resin composition exhibiting a well-balanced curability and storage stability.

As the ethylenically unsaturated monomer having no epoxy group, an ethylenically unsaturated monomer (a) (i) having no acid anhydride group for preparing an acrylic polyanhydride (a) (i) is used. ) (2) includes the monomers described above.
Copolymerization can be performed in the same manner as above.

The number average molecular weight of the resulting acrylic polyepoxide is 500 to 10000, preferably 1000 to 8000, and more preferably 1500 to 5000. When the number average molecular weight is less than 500, the curability of the obtained coating film is lowered, and when it exceeds 10,000, the solid content of the obtained coating is lowered. The epoxy equivalent is 50 to 700, preferably 80 to 600, more preferably 100 to 5
00. When the epoxy equivalent is larger than the above upper limit, the curability of the resin composition becomes insufficient. Also, if it is less than the lower limit, it becomes too hard and the coating film becomes brittle, which is not preferable.

The above-mentioned hydroxyl group-containing ethylenically unsaturated monomer for preparing the ethylenically unsaturated monomer (a) (i) (2) having no acid anhydride group is also an ethylenically unsaturated monomer having no epoxy group. It can be used as a monomer.

In particular, when the hydroxyl group-containing ethylenically unsaturated monomer is used as the ethylenically unsaturated monomer having no epoxy group, the adhesion and recoatability of the resulting coating film are improved. Further, obtained by using a hydroxyl group-containing ethylenically unsaturated monomer as an ethylenically unsaturated monomer having no epoxy, an acrylic polyepoxide having a hydroxyl group and an epoxy group, as described below, a carboxyl group and a carboxylic acid ester group. Since the acrylic polycarboxylic acid (a) having ## STR3 ## reacts with both functional groups of the hydroxyl group and the epoxy to bond with each other, a stronger coating film can be obtained.

The hydroxyl value of the resulting acrylic polyepoxide is 5 to 300 mgKOH / g, preferably 10 to 200 mgKOH / g, and more preferably 15 to 150 mgKOH / g. If the hydroxyl value exceeds 300, the solid content of the coating composition will decrease and the cured coating film will not have sufficient water resistance, and if it is 5 or less, the adhesion will be poor.

Particularly preferred polyepoxides for use in the present invention are those of formula (c) (i) [Wherein R is a hydrogen atom or a methyl group, and X is (In the formula, Y is a linear or branched alkylene group having 2 to 8 carbon atoms, m is an integer of 3 to 7, and q is an integer of 0 to 4.), or ,formula (In the formula, R is a hydrogen atom or a methyl group, and n is 2 to 50.
Is an integer. ) Is an organic chain. ] 5 to 70% by weight of a hydroxyl group-containing ethylenically unsaturated monomer having the structure shown in (ii) and (ii) an epoxy group containing ethylenically unsaturated monomer 10 to
It is obtained by copolymerizing 60% by weight with 0 to 85% by weight of (iii) an ethylenically unsaturated monomer which does not share both a hydroxyl group and an epoxy group, if necessary.

In this case, the polyepoxide (c) having a hydroxyl group and an epoxy group has an average of preferably 2 to 12 epoxy groups, more preferably 3 to 10 epoxy groups, and an average of hydroxyl groups in one molecule. It has 0.5 to 10, more preferably 1 to 8.

The polyepoxide (c) component is used in an amount of 10 to 80% by weight, preferably 20 to 70% by weight, more preferably 30 to 65% by weight, based on the weight of the total solid content in the curable resin composition. Can be compounded. If the amount of the polyepoxide is less than 10% by weight, the curability of the obtained coating film is lowered, and if it exceeds 70% by weight, the yellowing resistance is deteriorated.

The curable resin composition of the present invention can be obtained by blending the thus obtained acrylic polycarboxylic acid (a), polyester polycarboxylic acid (b) and polyepoxide (c).

The acrylic polycarboxylic acid (a), polyester polycarboxylic acid (b) and polyepoxide (c) may be compounded in amounts and methods well known to those skilled in the art. Particularly when using an acrylic polycarboxylic acid having a carboxyl group and a carboxylic ester group as the acrylic polycarboxylic acid (a) and using a polyepoxide having a hydroxyl group and an epoxy group as the polyepoxide (c), excellent acid resistance is obtained. A curable resin composition having a high solid content that forms a coating film is obtained.

In this case, the molar ratio of the carboxyl group contained in the acrylic polycarboxylic acid (a) and the polyester polycarboxylic acid (b) to the epoxy group contained in the polyepoxide (c) is 1 / 1.4 to. 1 / 0.6, preferably 1 / 1.2
To 1 / 0.8 and a carboxyl group contained in the acrylic polycarboxylic acid (a) or a carboxylic acid ester group bonded to a carbon adjacent to the carbon bonded to the carboxyl group, a polyester polycarboxylic acid (b) and a polyepoxide (c)
It is preferable that the compounding is carried out in an amount such that the molar ratio with the hydroxyl group contained in is 1 / 2.0 to 1 / 0.5, more preferably 1 / 1.5 to 1 / 0.7.

Resin obtained when the ratio of the carboxyl group contained in the acrylic polycarboxylic acid (a) and the polyester polycarboxylic acid (b) to the epoxy group contained in the polyepoxide (c) exceeds 1 / 0.6 The curability of the composition decreases, and when it is less than 1 / 1.4, the coating film turns yellow. Acrylic polycarboxylic acid (a) a carboxyl group contained in a carboxyl group or a carbon group-bonding carbon adjacent to a carboxyl group-containing carbon and a polyester-based polycarboxylic acid (b) and a hydroxyl group contained in a polyepoxide (c) If the molar ratio is more than 1 / 0.5, the curability of the resulting resin composition is reduced, and if it is less than 1 / 2.0, the hydroxyl groups are excessive and the water resistance is reduced. This blending amount can be calculated from the hydroxyl value, acid value and epoxy equivalent of each polymer by a calculation method well known to those skilled in the art.

The curing mechanism of the curable resin composition of the present invention thus obtained is as follows. First, by heating, the carboxyl group in the polyacrylic polycarboxylic acid (a) reacts with the carboxylic acid ester group to produce an acrylic resin. Type polycarboxylic acid (a)
An acid anhydride group is formed therein and a free monoalcohol is formed. The produced monoalcohol is removed from the system by evaporation. The acid anhydride group formed in the polyacrylic polycarboxylic acid (a) is a polyester polycarboxylic acid.
By reacting with the hydroxyl group contained in (b) and the polyepoxide (c), a crosslinking point is formed and a carboxyl group is formed again. The carboxyl group and the carboxyl group present in the polyester polycarboxylic acid (b) react with the epoxy group present in the polyepoxide (c) to form a crosslinking point. In this way, the three types of polymers react with each other to promote curing and provide a high crosslink density.

In addition to the above-mentioned essential components, a binder component such as a silicone polymer may be added to the curable resin composition of the present invention as required. This is because it is effective in increasing the solid content concentration of the obtained resin composition.

Silicone polymers which can be preferably used in the present invention include, for example, compounds of the formula [In the formula, R ^{1 to} R ⁶ are independently an alkyl group having 1 to 10 carbon atoms, a carbon number of 1 to 10, provided that at least one of them has an alkoxy group and the other has an epoxy group. 1 to 10 phenyl group, 1 to 10 carbon atom phenethyl group,
Alkoxy groups having 1 to 5 carbon atoms and the formula R ⁷ --Si (O
_{^{R 8) 3, R 7 -Si}} (OR 8) 2 CH 3, R 7 -Si (OR 8) (CH
₃ ) ₂ and R ⁷ -Y (In the formula, R ⁷ is a linear or branched alkylene group or a linear or branched alkylene group having an ether bond or an ester bond, and R ⁸ has 1 to 1 carbon atoms. 5 is an alkyl group, Y is a chain or cyclic alkyl group having an epoxy group.), And 1 is an integer of 1 to 20, and m is Is an integer from 0 to 4 and n is an integer from 0 to 2. ] It is a silicone polymer which has an epoxy group and / or an alkoxy group as shown in these. However, the repeating units constituting the silicone polymer may be randomly arranged, and the order of the above formulas is not limited.

Examples of the silicone polymer having an epoxy group include "NUC Silicone" series manufactured by Nippon Unicar Co., Ltd. Examples of the silicone polymer containing an alkoxy group include "KC89-" manufactured by Shin-Etsu Chemical Co., Ltd.
"S" and the like. Examples of the silicone polymer having an epoxy group and an alkoxy group include "MKC silicate MSEP2" series manufactured by Mitsubishi Chemical Co., Ltd. and "NUC silicone" series manufactured by Nippon Unicar Co., Ltd.

The method for producing such a silicone polymer is described in the summary of the Symposium on Organosilicon Materials Chemistry, 1990, No. 29.
Pp. 30-30. The epoxy group may be present in the middle or at the end of the chain or cyclic hydrocarbon chain. In the silicone polymer (II), the chain-like or cyclic hydrocarbon having an epoxy group represented by Y is represented by the following formula, for example.

[0075]

Embedded image

[In the formula, R ¹¹ , R ¹² and R ¹³ are hydrocarbons having up to 4 carbon atoms. ]

In the present specification, the epoxy equivalent means
The g number of a compound containing 1 g equivalent of an epoxy group is represented, the alkoxy equivalent is a g number of a compound containing 1 g equivalent of an alkoxy group, and the hydroxyl equivalent is a g of a compound containing 1 g equivalent of a hydroxyl group.
Represents a number.

The epoxy equivalent of this silicone polymer is
From 100 to 1500, the alkoxy equivalent weight is from 50 to 1500. If the epoxy equivalent is less than 100, the storage stability of the paint is poor, and
If it exceeds 0, the curability is poor. The preferred range of epoxy equivalent is 140 to 1000, more preferably 180 to 700. The preferable range of the alkoxy equivalent is 60 to 800,
It is more preferably 80 to 500.

The silicone polymer component having such an epoxy group and an alkoxy group is used in an amount of up to 30% by weight, preferably 1 to 20% by weight, and more preferably, based on the weight of the total solid content in the curable resin composition. It may be incorporated in an amount of 3 to 15% by weight. When the amount of the silicone polymer component exceeds 30% by weight, the storage stability of the obtained coating composition is deteriorated.

In the present invention, the epoxy group and /
Alternatively, a silicone polymer having a hydroxyl group and a carboxyl group may be used together with or instead of the silicone polymer having an alkoxy group. The silicone polymer having a hydroxyl group and a carboxyl group,
It is obtained by a half-esterification reaction of a silicone polymer having a hydroxyl group and an acid anhydride group-containing compound.

The number average molecular weight of this silicone polymer is
It is 500 to 6000, preferably 1000 to 4500, the hydroxyl value is 2 to 120, preferably 10 to 80, and the acid value is 20 to 180, preferably 35 to 150. When the number average molecular weight, the hydroxyl value or the acid value exceeds the upper limit of the above range, it becomes difficult to prepare a coating material having a sufficiently high solid content, and when the number average molecular weight, the hydroxyl value or the acid value is less than the lower limit, the curability of the obtained coating material decreases.

Silicone polymers having hydroxyl groups are commercially available.

[0083]

Embedded image

Examples include KR-2001 manufactured by Shin-Etsu Chemical Co., Ltd. and NUC-Silicone series manufactured by Nippon Unicar Co., Ltd.

The silicone polymer having a hydroxyl group is 1
It is preferable to have an average of 3 to 12 hydroxyl groups in the molecule. If the average number of hydroxyl groups is less than 3, the curability is insufficient,
When it exceeds 12, the viscosity becomes high and it becomes difficult to increase the solid content in the resin composition.

The acid anhydride group-containing compound has a room temperature to 120 ° C.
It provides carboxy functionality by reacting with hydroxyl groups under normal reaction conditions such as ° C and atmospheric pressure. Carbon number 8
It is preferable to use an acid anhydride group-containing compound having a saturated or unsaturated cyclic group of 12 to obtain good resin compatibility.

Examples of the acid anhydride group-containing compound include hexahydrophthalic anhydride, phthalic anhydride, 4-methylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, trimellitic anhydride and the like.

The half-esterification reaction between the hydroxyl group-containing silicone polymer and the acid anhydride group-containing compound is carried out according to a conventional method, for example, at a temperature of room temperature to 120 ° C. for 30 minutes to 8 hours. When the reaction is carried out for a long time at a temperature exceeding 120 ° C., a polyesterification reaction occurs to produce a high molecular weight silicone polyester. Such a silicone polyester is not preferable for use in the present invention because it has a small number of functional groups and a high viscosity.

The silicone polymer component containing such a hydroxyl group and a carboxyl group is up to 30% by weight, preferably 1 to 20% by weight, and more preferably, based on the weight of the total solid content in the curable resin composition. It may be incorporated in an amount of 3 to 15% by weight. When the amount of the silicone polymer component exceeds 30% by weight, the storage stability of the obtained coating composition is deteriorated.

When a silicone polymer component having an epoxy group and an alkoxy group and a silicone polymer component having a hydroxyl group and a carboxyl group are used in combination, the total amount thereof is the weight of all solids in the curable resin composition. It may be incorporated in an amount of up to 30% by weight, preferably 1 to 20% by weight, more preferably 3 to 15% by weight. When the amount of the silicone polymer component exceeds 30% by weight, the storage stability of the obtained coating composition is deteriorated.

In addition to the above-mentioned components, the curable resin composition of the present invention may contain a curing catalyst usually used in the esterification reaction of an acid with an epoxy such as a quaternary ammonium salt. Specific examples of other catalysts that can be used in the curable resin composition of the present invention include benzyltriethylammonium chloride or bromide, tetrabutylammonium chloride or bromide, salicylate or glycolate, and paratoluenesulfonate. These curing catalysts may be used as a mixture.

The curing catalyst can be used generally in an amount of 0.01 to 3.0% by weight, preferably 0.1 to 1.5% by weight, more preferably 0.4 to 1.2% by weight, based on the solid content of the resin composition. If the amount of the catalyst used is less than 0.01% by weight, the curability will decrease, and 3.0
If it exceeds the weight percentage, the storage stability decreases.

Further, Japanese Patent Laid-Open No. 2-151651 and No. 2-
As described in JP-A-279713, tin compounds may be used in combination therewith. Examples of the tin-based catalyst include dimethyltin bis (methylmalate), dimethyltin bis (ethylmalate), dimethyltin bis (butylmalate), dibutyltin bis (butylmalate), and the like.

The tin-based compound is generally contained in an amount of 0.05 to 6% by weight, preferably 0.1 to 4.0% by weight, based on the solid content of the resin composition.
More preferably, it can be used in an amount of 0.2 to 2.0% by weight. If the amount of the tin-based compound used is less than 0.05% by weight, the storage stability will decrease, and if it exceeds 6% by weight, the weather resistance will decrease.
When the curing catalyst and the tin compound are used in combination, the weight ratio of the curing catalyst and the tin compound is preferably 1/4 to 1 / 0.2.

A blocked isocyanate may be added to the resin composition of the present invention in order to increase the crosslink density and improve the water resistance. In addition, in order to improve the weather resistance of the coating film,
An ultraviolet absorber, a hindered amine light stabilizer, an antioxidant and the like may be added. Further, crosslinked resin particles as a rheology control agent or a surface conditioner for adjusting the appearance may be added. Furthermore, alcohol-based solvents (for example, methanol, ethanol, propanol, butanol, etc.), hydrocarbon-based solvents, ester-based solvents and the like may be used as diluents for viscosity adjustment and the like.

When the crosslinked resin particles are used, 0.01 to 1 is used with respect to 100 parts by weight of the resin solid content of the curable resin composition of the present invention.
It is added in an amount of 0 parts by weight, preferably 0.1-5 parts by weight.
If the amount of the crosslinked resin particles added exceeds 10 parts by weight, the appearance deteriorates, and if it is less than 0.01 parts by weight, the rheology control effect cannot be obtained.

The resin used in the present invention has an acid group as a functional group. Therefore, by neutralizing with an amine, it is possible to obtain an aqueous resin composition using water as a medium.

The present invention also provides a coating composition containing the above-mentioned curable resin composition as a binder component. The method for producing the coating composition of the present invention is not particularly limited, and any method known to those skilled in the art can be used.

The coating composition of the present invention can be applied by spray coating, brush coating, dip coating, roll coating, flow coating or the like. The substrate may be primed or mid-coated if desired. Known undercoat paints and intermediate paints can be used.

The coating composition according to the invention can advantageously be used on any substrate, such as wood, metal, glass, cloth, plastics, foams and the like, especially on plastics and metal surfaces such as steel, aluminum and their alloys. Generally, the film thickness will vary depending on the desired application. Often 0.
5 to 3 mils is useful.

After coating the substrate, the coating film is cured. Curing gives a cured coating film with a high degree of crosslinking at 100 to 180 ° C, preferably 120 ° C to 160 ° C. The curing time varies depending on the curing temperature and the like, but curing at 120 ° C to 160 ° C for 10 to 30 minutes is suitable.

In a preferred embodiment of the present invention, the coating film is provided by a method including the following steps. A step of applying a water-based or solvent-based base coating on an undercoated or intermediate-coated substrate; without curing the base coating,
A coating film forming method comprising: a step of applying the clear coating composition according to claim 9; and a step of curing the base coating film and the clear coating film by heating.

[0103]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited thereto. Unless otherwise specified, the blending amount is based on weight.

Synthesis Example 1 Synthesis of acrylic polycarboxylic acid (a) -1 700 parts by weight of xylene and 100 parts of Solvesso in a 3 L reaction tank equipped with a thermometer, a stirrer, a cooling tube, a nitrogen introducing tube, and an appropriate funnel.
(Aromatic hydrocarbon solvent manufactured by Esso Co.) was added in an amount of 500 parts by weight, and the temperature was raised to 130 ° C. In the above container, using a suitable funnel, 300 parts by weight of styrene monomer, 350 parts by weight of 2-ethylhexyl acrylate, 150 parts by weight of isobutyl methacrylate, 200 parts by weight of acrylic acid, and t-butylperoxy 2-.
A solution of 150 parts by weight of ethyl hexanoate and 300 parts by weight of xylene was applied for 3 hours. After the dropping was completed, the temperature was maintained at 130 ° C. for 30 minutes, and then a solution of 20 parts by weight of t-butylperoxy 2-ethylhexanoate and 20 parts by weight of xylene was added dropwise over 30 minutes. 1 more after this dropping
After continuing the reaction at 130 ° C. for a period of time, 1100 parts by weight of a solvent was removed, and a nonvolatile content containing acrylic polycarboxylic acid (a) -1 having a number average molecular weight of 1800 and an acid value of 156 mgKOH / g (solid content). I got 70% varnish.

Synthesis Example 2 Synthesis of Acrylic Polycarboxylic Acid (a) -2 In the same manner as in Synthesis Example 1 except that the composition shown in Table 1 below was used, the number average molecular weight was 1900 and the acid value was 140 mgKOH / g. A varnish containing acrylic polycarboxylic acid (a) -2 and having a nonvolatile content of 70% was obtained.

[0106]

[Table 1]

Synthesis Example 3 Synthesis of Acrylic Polycarboxylic Acid (a) -3 In the same manner as in Synthesis Example 1 except that the composition shown in Table 2 below was used, the number average molecular weight was 1800 and the acid value was 150 mgKOH / g. A varnish having a nonvolatile content of 70% containing an acrylic polycarboxylic acid (a) -3 was obtained.

[0108]

[Table 2]

Synthesis Example 4 Synthesis of Acrylic Polycarboxylic Acid (a) -4 Having Carboxyl Group and Carboxylic Acid Ester Group 3 L reaction vessel equipped with thermometer, stirrer, cooling tube, nitrogen introducing tube, and appropriate funnel. Xylene 700 parts, Solvesso 100 350
Parts were charged and the temperature was raised to 130 ° C. Using an appropriate funnel in the above container, 300 parts of styrene, 109 parts of 2-ethylhexyl methacrylate, 325 parts of isobutyl acrylate, acrylic acid
A solution consisting of 26 parts, 240 parts of maleic anhydride, 300 parts of propylene glycol monomethyl ether acetate, and 150 parts of t-butylperoxy 2-ethylhexanoate and 150 parts of xylene was applied for 3 hours. After the dropping was completed, the temperature was maintained at 130 ° C. for 30 minutes, and then a solution containing 20 parts of t-butylperoxy 2-ethylhexanoate and 20 parts of xylene was added dropwise over 30 minutes. After this dropping, for another hour
After continuing the reaction at 130 ° C., 1100 parts of the solvent was removed to obtain a varnish having a nonvolatile content of 70% containing the acrylic polyanhydride (a) (i) having a number average molecular weight of 2000.

1590 parts of the obtained varnish was mixed with 125 parts of methanol.
Parts were added and reacted at 70 ° C. for 23 hours to obtain a varnish containing an acrylic polycarboxylic acid (a) -4 having an acid value of 158 mg KOH / g.
The infrared absorption spectrum of this acrylic polycarboxylic acid (a) -4 was measured, and the absorption of an acid anhydride group (1785 cm
^-1 ) disappeared.

Synthesis Example 5 Synthesis of Acrylic Polycarboxylic Acid (a) -5 Having Carboxyl Group and Carboxylic Acid Ester Group The same procedure as in Synthesis Example 4 was repeated except that the composition shown in Table 3 below was used. A varnish having a nonvolatile content of 65% containing an acrylic polycarboxylic acid (a) -5 having a molecular weight of 2000 and an acid value of 165 mgKOH / g was obtained.

[0112]

[Table 3]

Synthesis Example 6 Synthesis of Acrylic Polycarboxylic Acid (a) -6 Having Carboxyl Group and Carboxylic Acid Ester Group The same procedure as in Synthesis Example 4 was repeated except that the composition shown in Table 4 below was used. A varnish having a nonvolatile content of 65% containing an acrylic polycarboxylic acid (a) -6 having a molecular weight of 2100 and an acid value of 157 mgKOH / g was obtained.

[0114]

[Table 4]

Synthesis Example 7 Synthesis of polyester polycarboxylic acid (b) -1 In a reaction vessel equipped with a thermometer, a stirrer, a cooling pipe, and a nitrogen introducing pipe.
278 parts of ethyl 3-ethoxypropionate, 268 parts of trimethylolpropane, 228 parts of ε-caprolactone and 0.1 part of dibutyltin oxide were charged and the temperature was raised to 150 ° C.

After holding at 150 ° C. for 2 hours, 616 parts of hexahydrophthalic anhydride dissolved by heating were added,
Keep at 150 ℃ for 1 hour, polyester polycarboxylic acid with number average molecular weight 800, weight average molecular weight / number average molecular weight = 1.18, acid value 202 mg KOH / g (solid content) and hydroxyl value 101 mg KOH / g (solid content) ( A varnish having a nonvolatile content of 80% containing b) -1 was obtained.

Synthesis Example 8 Synthesis of Polyester Polycarboxylic Acid (b) -2 In a reaction vessel equipped with a thermometer, a stirrer, a cooling pipe and a nitrogen introducing pipe.
271 parts of ethyl 3-ethoxypropionate, 268 parts of trimethylolpropane, 200 parts of δ-valerolactone and 0.1 part of dibutyltin oxide were charged and the temperature was raised to 150 ° C.

After holding at 150 ° C. for 2 hours, 616 parts of hexahydrophthalic anhydride dissolved by heating were added,
Hold at 150 ° C for 1 hour, number average molecular weight 800, weight average molecular weight / number average molecular weight = 1.17, acid value 207 mgKOH / g (solid content),
A varnish having a nonvolatile content of 80% containing a polyester polycarboxylic acid (b) -2 having a hydroxyl value of 103 mgKOH / g (solid content) was obtained.

Synthesis Example 9 Synthesis of polyester polycarboxylic acid (b) -3 In a reaction vessel equipped with a thermometer, a stirrer, a cooling pipe, and a nitrogen introducing pipe.
234 parts of ethyl 3-ethoxypropionate, 134 parts of trimethylolpropane, 342 parts of ε-caprolactone and 0.1 part of dibutyltin oxide were charged and the temperature was raised to 150 ° C.

After holding at 150 ° C. for 2 hours, 462 parts of hexahydrophthalic anhydride dissolved by heating was added,
Hold at 150 ℃ for 1 hour, number average molecular weight 1200, weight average molecular weight / number average molecular weight = 1.22, acid value 179mgKOH / g (solid content)
Non-volatile content of 80 including polyester polycarboxylic acid (b) -3
% Varnish was obtained.

Synthesis Example 10 Synthesis of polyester polycarboxylic acid (b) -4 In a reaction vessel equipped with a thermometer, a stirrer, a cooling pipe, and a nitrogen introducing pipe.
275 parts of ethyl 3-ethoxypropionate, 136 parts of pentaerythritol, 228 parts of ε-caprolactone and 0.1 part of dibutyltin oxide were charged and the temperature was raised to 180 ° C.

After holding at 180 ° C. for 2 hours, 462 parts of hexahydrophthalic anhydride dissolved by heating was added,
Keep at 150 ℃ for 1 hour, polyester polycarboxylic acid of number average molecular weight 1100, weight average molecular weight / number average molecular weight = 1.20, acid value 204 mgKOH / g (solid content), hydroxyl value 68 mgKOH / g (solid content) A varnish having a nonvolatile content of 75% including b) -4 was obtained.

Synthesis Example 11 Synthesis of Polyester Polycarboxylic Acid (b) -5 In a reaction vessel equipped with a thermometer, a stirrer, a cooling pipe and a nitrogen introducing pipe, 136 parts of pentaerythritol and 91 of ε-caprolactone were placed.
2 parts and 0.2 part of dibutyltin oxide were charged and the temperature was raised to 180 ° C.

After the mixture was kept at 180 ° C. for 2 hours, 397 parts of ethyl 3-ethoxypropionate was added, 538 parts of hexahydrophthalic anhydride dissolved by heating was added, and the mixture was kept at 150 ° C. for 1 hour, Number average molecular weight 2500, weight average molecular weight / number average molecular weight = 1.35, acid value 124 mg KOH / g (solid content), hydroxyl value 25 mg KOH / g (solid content) Polyester polycarboxylic acid (b) -5 Non-volatile content 80% Got a varnish.

Synthesis Example 12 Synthesis of polyester polycarboxylic acid (b) -6 In a reaction vessel equipped with a thermometer, a stirrer, a cooling pipe, and a nitrogen introducing pipe.
275 parts of ethyl 3-ethoxypropionate, 136 parts of pentaerythritol, 456 parts of ε-caprolactone and 0.1 part of dibutyltin oxide were charged and the temperature was raised to 180 ° C.

After being kept at 180 ° C. for 2 hours, 576 parts of trimellitic anhydride was added and kept at 150 ° C. for 1 hour to give a number average molecular weight of 1800 and a weight average molecular weight / number average molecular weight =
A varnish having a nonvolatile content of 75% containing a polyester polycarboxylic acid (b) -6 having an acid value of 1.25, an acid value of 192 mgKOH / g (solid content) and a hydroxyl value of 48 mgKOH / g (solid content) was obtained.

Synthesis Example 13 Synthesis of Polyester Polycarboxylic Acid (b) -7 In a reaction vessel equipped with a thermometer, a stirrer, a cooling tube and a nitrogen introducing tube, 136 parts of pentaerythritol and 91 of ε-caprolactone were placed.
2 parts and 0.2 part of dibutyltin oxide were charged and the temperature was raised to 180 ° C.

After the mixture was kept at 180 ° C. for 2 hours, 215 parts of ethyl 3-ethoxypropionate was added, 154 parts of hexahydrophthalic anhydride dissolved by heating was added, and the mixture was kept at 150 ° C. for 1 hour. Number average molecular weight 2200, weight average molecular weight / number average molecular weight = 1.32, acid value 47 mgKOH / g (solid content), hydroxyl value 140 mgKOH / g (solid content) polyester polycarboxylic acid (b) -7 non-volatile content 80% Got a varnish.

Synthesis Example 14 Synthesis of polyester polycarboxylic acid (b) -8 210 parts of isophthalic acid and 3 parts of azelaic acid 3 in a reaction tank equipped with a thermometer, a stirrer, a cooling pipe, a nitrogen introducing pipe, a water separator and a rectification column.
70 parts, 400 parts of trimethylolpropane, 100 parts of neopentyl glycol, and 50 parts of Cardura E (manufactured by Shell Chemical Co.) were charged and heated. When the raw material melts and stirring becomes possible, add 0.2 parts of dibutyltin oxide and start stirring.
The temperature was raised to 20 ° C. However, from 180 ℃ to 220 ℃,
The temperature was raised at a constant heating rate over 3 hours. The generated condensed water was distilled out of the system. When the temperature reached 220 ° C., it was kept warm, and after 1 hour of warm keeping, 30 parts of xylene as a reflux solvent was gradually added to the reaction tank, and the reaction was switched to the condensation in the presence of the solvent to continue the reaction. When the acid value of the resin reached 10.0, cool to 150 ° C, add 420 parts of phthalic anhydride and incubate for 1 hour.
It was cooled to 00 ° C. Furthermore, 275 parts of ethyl 3-ethoxypropionate and 275 parts of butyl acetate are added to give a number average molecular weight of 4,200,
A varnish having a nonvolatile content of 70% containing a polyester polycarboxylic acid (b) -8 having a weight average molecular weight / number average molecular weight of 3.3 and an acid value of 115 mgKOH / g (solid content) was obtained.

Synthesis Example 15 Synthesis of polyepoxide (c) -1 250 parts of xylene and 200 parts of propylene glycol monomethyl ether acetate were charged into a 2 L reaction tank equipped with a thermometer, a stirrer, a cooling tube, a nitrogen introducing tube, and an appropriate funnel. , 130 ℃
The temperature was raised to.

Using a dropping funnel, 450 parts of glycidyl methacrylate and isobornyl methacrylate 2 were added to the above reaction tank.
A solution containing 36 parts, 64 parts of 4-hydroxybutyl acrylate, 250 parts of t-butylstyrene, and 110 parts of t-butylperoxy 2-ethylhexanoate and 150 parts of xylene was added dropwise over 3 hours.

After the dropping was completed, the temperature was maintained at 130 ° C. for 30 minutes, and then a solution containing 10 parts of t-butylperoxy 2-ethylhexanoate and 50 parts of xylene was added dropwise for 30 minutes.

After completion of this dropping, the reaction was continued at 130 ° C. for another hour, then 270 parts of the solvent was removed, and the number average molecular weight was 2
A varnish having a nonvolatile content of 72% containing 200, an epoxy equivalent of 316, a hydroxyl value of 25 mgKOH / g (solid content) and an acrylic polyepoxide (c) -1 was obtained.

Synthesis Example 16 Synthesis of polyepoxide (c) -2 250 parts of xylene and 200 parts of propylene glycol monomethyl ether acetate were charged into a 2 L reaction tank equipped with a thermometer, a stirrer, a cooling tube, a nitrogen introducing tube, and an appropriate funnel. , 135 ° C
The temperature was raised to.

Using a dropping funnel, 500 parts of glycidyl methacrylate and 250 parts of isobutyl methacrylate were added to the above reaction tank.
Parts, 250 parts of t-butylstyrene, and 120 parts of t-butylperoxy 2-ethylhexanoate and 140 parts of xylene were added dropwise over 3 hours.

After the dropping was completed, the temperature was kept at 135 ° C. for 30 minutes, and then a solution containing 10 parts of t-butylperoxy 2-ethylhexanoate and 50 parts of xylene was added dropwise for 30 minutes.

After the completion of this dropping, the reaction was continued for another hour at 135 ° C., and then 270 parts of the solvent was removed to obtain a number average molecular weight of 1
Acrylic polyepoxide (c) with 800 and epoxy equivalent of 284-
A varnish having a nonvolatile content of 72% containing 2 was obtained.

Synthesis Example 17 Synthesis of polyepoxide (c) -3 250 parts of xylene and 200 parts of propylene glycol monomethyl ether acetate were charged into a 2 L reaction tank equipped with a thermometer, a stirrer, a cooling tube, a nitrogen introducing tube, and an appropriate funnel. , 130 ℃
The temperature was raised to.

Using a dropping funnel in the above reaction vessel, 550 parts of 3,4-epoxycyclohexylmethyl methacrylate, 130 parts of isobornyl acrylate, 70 parts of 2-hydroxyethyl methacrylate, 250 parts of t-butylstyrene, and 110 parts t-butyl peroxy 2-ethylhexanoate and 1 xylene
A solution consisting of 50 parts was added dropwise over 3 hours.

After the dropping was completed, the temperature was maintained at 130 ° C. for 30 minutes, and then a solution containing 10 parts of t-butylperoxy 2-ethylhexanoate and 50 parts of xylene was added dropwise for 30 minutes.

After completion of this dropping, the reaction was continued at 130 ° C. for an additional hour, and then 270 parts of the solvent was removed to obtain a number average molecular weight of 2
A varnish having a nonvolatile content of 72% containing 200, an epoxy equivalent of 357, a hydroxyl value of 30 mgKOH / g (solid content) and an acrylic polyepoxide (c) -3 was obtained.

Synthesis Example 18 Synthesis of polyepoxide (c) -4 700 parts of xylene and 525 parts of propylene glycol monomethyl ether acetate were charged into a 3 L reaction tank equipped with a thermometer, a stirrer, a cooling tube, a nitrogen introducing tube, and an appropriate funnel. , 130 ℃
The temperature was raised to.

Using a dropping funnel in the above reaction tank, 200 parts of Beovar 9, 300 parts of glycidyl methacrylate, 230 parts of 4-hydroxybutyl acrylate, 340 parts of cyclohexyl methacrylate, and t-butylperoxy 2 ethylhexahexate were used. 3 parts of a solution consisting of 120 parts of Noate and 200 parts of xylene
It dripped over time.

After the dropping was completed, the temperature was maintained at 130 ° C. for 30 minutes, and then a solution containing 10 parts of t-butylperoxy 2-ethylhexanoate and 50 parts of xylene was added dropwise for 30 minutes.

After the completion of this dropping, the reaction was continued at 130 ° C. for another hour, then 1200 parts of the solvent was removed, and the number average molecular weight was 18
A varnish having a nonvolatile content of 77% containing 00, an epoxy equivalent of 473, a hydroxyl value of 90 mgKOH / g (solid content) and an acrylic polyepoxide (c) -4 was obtained.

Synthesis Example 19 Synthesis of polyepoxide (c) -5 250 parts of xylene and 300 parts of propylene glycol monomethyl ether acetate were charged into a 2 L reaction tank equipped with a thermometer, a stirrer, a cooling tube, a nitrogen introducing tube, and a suitable funnel. , 135 ° C
The temperature was raised to.

Using the dropping funnel, 355 parts of glycidyl methacrylate and 90 parts of isobutyl methacrylate were added to the above reaction tank.
Parts, t-butyl styrene 250 parts, 4-hydroxybutyl acrylate 238 parts, 2-hydroxyethyl methacrylate 67 parts, t
A solution of 140 parts of -butylperoxy 2-ethylhexanoate and 100 parts of xylene was added dropwise over 3 hours.

After the dropping was completed, the temperature was kept at 135 ° C. for 30 minutes, and then a solution containing 10 parts of t-butylperoxy 2-ethylhexanoate and 30 parts of xylene was added dropwise for 30 minutes.

After completion of the dropping, the reaction was continued at 135 ° C. for 1 hour, 320 parts of the solvent was removed, and the number average molecular weight was 1800.
A varnish having a nonvolatile content of 72% containing an acrylic polyepoxide (c) -5 having an epoxy equivalent of 400 and a hydroxyl value of 122 mgKOH / g was obtained. Synthesis Example 20 Synthesis of acrylic polycarboxylic acid (a) -7 having carboxyl group and carboxylic acid ester group Xylene 330 in a 3 L reaction tank equipped with a thermometer, a stirrer, a cooling tube, a nitrogen introducing tube, and a suitable funnel. And 100 parts of propylene glycol monomethyl ether acetate were charged, 130
The temperature was raised to ° C. In the above container, using a suitable bottom funnel, styrene 300 parts, 2-ethylhexyl methacrylate 120 parts, 2-ethylhexyl acrylate 369 parts, acrylic acid 26 parts, maleic anhydride 185 parts, propylene glycol monomethyl ether acetate 300 parts, Then, a solution of 100 parts of t-butylperoxy 2-ethylhexanoate and 100 parts of xylene was applied for 3 hours. 30 minutes after dripping 13
After holding at 0 ° C., a solution of 10 parts of t-butylperoxy 2-ethylhexanoate and 60 parts of xylene was added dropwise over 30 minutes. After completion of this dropping, the reaction was continued at 130 ° C. for an additional hour to obtain a varnish having a nonvolatile content of 52% containing the acrylic polyanhydride (a) (i) having a number average molecular weight of 3000.

To 2000 parts of the obtained varnish, 90 parts of methanol was added and reacted at 70 ° C. for 23 hours to obtain a varnish containing an acrylic polycarboxylic acid (a) -7 having an acid value of 126 mgKOH / g. still,
An infrared absorption spectrum of this acrylic polycarboxylic acid (a) -7 was measured, and it was confirmed that the absorption (1785 cm ^-1 ) of the acid anhydride group disappeared. Synthesis Example 21 Synthesis of polyepoxide (c) -7 A 3 L reaction vessel equipped with a thermometer, a stirrer, a cooling pipe, a nitrogen introducing pipe, and an appropriate funnel was charged with 520 parts of xylene and 50 parts of propylene glycol monomethyl ether acetate, and 126 ° C.
The temperature was raised to.

Using a dropping funnel, 250 parts of styrene, 379 parts of glycidyl methacrylate, 243 parts of isobornyl methacrylate, and 4-hydroxybutyl acrylate were added to the above reaction tank.
A solution of 28 parts and 110 parts of t-butylperoxy 2-ethylhexanoate and 110 parts of xylene was added dropwise over 3 hours.

After the dropping was completed, the temperature was maintained at 126 ° C. for 30 minutes, and then a solution containing 10 parts of t-butylperoxy 2-ethylhexanoate and 20 parts of xylene was added dropwise for 30 minutes.

After the completion of this dropping, the reaction was continued at 126 ° C. for another hour to give a number average molecular weight of 3,000 and an epoxy equivalent of 37.
5. A varnish containing an acrylic polyepoxide (c) -7 having a hydroxyl value of 90 mgKOH / g (solid content) and a nonvolatile content of 58% was obtained.

Example 1 Preparation of Crosslinked Resin Particles A reaction vessel equipped with a stirring and heating device, a thermometer, a nitrogen introducing tube, a cooling tube and a decanter was placed in 213 parts of bishydroxyethyl taurine, 208 parts of neopentyl glycol and phthalic anhydride.
296 parts, 376 parts of azelaic acid and 30 parts of xylene were charged and the temperature was raised. The water produced by the reaction was removed by azeotropic distillation with xylene. It takes about 3 hours to start the reaction solution at 210
The temperature was set to 0 ° C., and stirring and dehydration were continued until the acid value corresponding to the carboxylic acid became 135, and the reaction was continued. After cooling the liquid temperature to 140 ° C., 500 parts of “CARDURA E10” (versatiic acid glycidyl ester manufactured by Shell Co.) was added dropwise over 30 minutes, and then stirring was continued for 2 hours to complete the reaction. A zwitterionic group-containing polyester resin having a solid acid value of 55, a hydroxyl value of 91 and a number average molecular weight of 1250 was obtained.

This amphoteric ion group-containing polyester resin 10
Parts, 140 parts deionized water, dimethylethanolamine 1
Parts, styrene 50 parts and ethylene glycol dimethacrylate 50 parts were vigorously stirred in a stainless beaker to prepare a monomer suspension. Further, an initiator aqueous solution was prepared by mixing 0.5 part of azobiscyanovaleric acid, 40 parts of deionized water and 0.32 part of dimethylethanolamine.

A reaction vessel equipped with a stirring and heating device, a thermometer, a nitrogen introducing tube and a cooling tube was charged with 5 parts of the above amphoteric ion group-containing polyester resin, 280 parts of deionized water and 0.5 part of dimethylethanolamine, and the temperature was raised to 80 ° C. Warmed. The monomer suspension and 40.82 parts of the aqueous initiator solution were simultaneously added dropwise over 60 minutes, and after the reaction was continued for another 60 minutes, the reaction was terminated. A crosslinked resin particle emulsion having a particle size of 55 nm as measured by dynamic light scattering was obtained.

Xylene was added to this emulsion, water was removed by azeotropic distillation under reduced pressure, and the medium was replaced with xylene to obtain a xylene solution of crosslinked resin particles having a solid content of 20% by weight.

Preparation of Clear Coating Composition Acrylic polycarboxylic acid (a) -1 obtained in Synthetic Example 1 and polyester polycarboxylic acid (b) -1 obtained in Synthetic Example 7 with the composition shown in Table 3 were synthesized. Polyepoxide (c) -1, obtained in Example 15, 0.5 part of tetrabutylammonium bromide curing catalyst, 0.5 part of dibutyltin bis (butyl maleate) curing catalyst, 2 parts of UV absorber "Tinuvin 900" manufactured by Ciba-Geigy, Sankyo 1 part of a photo-stabilizing agent "Sanol LS-440" manufactured by Mfg. Co. and 0.1 part of a surface preparation agent "Modaflow" manufactured by Monsanto Co. were mixed with a disper stirring to prepare a curable resin composition. To the obtained resin composition, 10 parts of a xylene solution of crosslinked resin particles prepared as described above was added, and then butyl acetate / xylene = 1 /
A Ford cup No. 4 was adjusted to a viscosity of 30 seconds with a solvent consisting of 1 to obtain a clear coating composition.

Paint Nonvolatile (NV) Paint viscosity was adjusted to 30 seconds at 20 ° C. using Ford cup No. 4, 0.5 g of the coating composition was precisely weighed and diluted with 3 cc of toluene, and then at 110 ° C. for 1 hour. The non-volatile content (% by weight) of the baking paint was measured.

On the other hand, a cationic electrodeposition coating (Power Top U-5 manufactured by Nippon Paint Co., Ltd.) was applied to a 0.8 mm thick phosphoric acid-treated steel sheet.
0) and intermediate coating (Olga P-2 made by Nippon Paint Co., Ltd.)
To the process test plate coated to have a dry thickness of 25 μm and 40 μm, respectively, a solvent-type high solid base paint (manufactured by Nippon Paint Co., Ltd.) is air-spray coated so that the thickness of the dry coating film is about 16 μm, A base coating film was formed by setting for about 7 minutes.

On top of that, the obtained clear coating composition was added,
Use an electrostatic coating machine ("Auto Rea" manufactured by Randsburg Gemma) to apply a spraying pressure of 5 kg / cm ² to a dry film thickness of about 40 μm, and after setting for about 7 minutes, set at 25 ° C at 140 ° C. Baked for a minute.

The solvent-type high solid base paint was blended with an acrylic resin (nonvolatile content 80% by Nippon Paint Co., Ltd.).
%, Hydroxyl value 100, acid value 30 and number average molecular weight 1800) 20
Department, Nippon Paint Co., Ltd. polyester (nonvolatile content 80%,
Hydroxyl value 100, acid value 12 and number average molecular weight 2600) 30 parts, Mitsui Cytec melamine resin "Cymel 202" (nonvolatile content 80%) 40 parts, Mitsui Cytec melamine resin "Cymel 327" (nonvolatile content 90%) 10 parts, "Alpaste Al60-600" (nonvolatile content 65%) manufactured by Toyo Aluminum Co., Ltd. and 7 parts isopropyl alcohol.

The performance of the obtained coating film was evaluated as follows. The results are shown in Table 6.

Pencil hardness It was conducted according to JIS K5400 8, 4.2.

Water resistance The obtained cured coating film was immersed in tap water at 40 ° C. for 10 days, and then the surface of the coating film was visually evaluated according to the following criteria. When no change is observed ○ When a slight trace is seen △ When an abnormality is found in the coating film ×

A 2 × 2 cm flannel cloth coated with 1 g of 50% aqueous dispersion of scratch-resistant cleanser (“New Homing Cleanser” (Kao Corporation, 87% abrasive, 5% surfactant and others)) was applied. It was attached to the sliding head of a shake-type dyeing friction fastness tester (manufactured by Daiei Kagaku Seiki Co., Ltd.). The sliding head loaded with 500 g was reciprocated 20 times on the cured coating film obtained, and then the 20 ° gloss of the test portion was measured to calculate the gloss retention rate (%).

Acid resistance The obtained cured coating film was added to 0.5 ml of a 1% by weight aqueous solution of sulfuric acid.
After contact for 30 minutes at 5 ° C., the coating film surface was visually evaluated according to the following criteria. When no abnormality is observed 5 When traces are slightly visible 4 When traces are clearly observed 3 When several aggregates of fine holes are observed 2 When aggregates of fine holes are observed on the entire surface 1

Weather resistance Iwasaki Denki's "Eye Super UV Tester SUV-W13" has a black panel temperature of 63 ° C and a humidity of 70% of 100 mW /
24 hours of cm ² UV irradiation and 50 black panel temperature
After leaving for 24 hours under the condition of 100 ° C. and 100% humidity as one cycle, 5 cycles were performed, and then the coating film surface was visually evaluated according to the following criteria. When no abnormality is observed ○ When some cracks are observed △ When significantly cracked ×

Adhesiveness (non-sand recoating property) A high solid base paint (manufactured by Nippon Paint Co., Ltd.) is air spray-painted on a coated paint plate so that the thickness of the dry paint film is about 16 μm, and the setting is made for about 7 minutes. did. However,
When an aqueous base paint (manufactured by Nippon Paint Co., Ltd.) was used (Examples 16 and 17), air spray coating was performed, setting was performed for about 1 minute, and then preheating was performed at 80 ° C. for 5 minutes.

Then, the formulations shown in Tables 6 and 7 (solid content)
Each of the resin components was blended with, the viscosity was adjusted to 30 seconds with Ford Cup No. 4, and the resulting clear coating composition was atomized with an electrostatic coating machine "Auto-Rea" (manufactured by Landsberg Gemma). 5 kg / cm
^It was painted so that the dry film thickness would be about 40 μm in 2, and set for about 7 minutes, and then baked at 160 ° C. for 30 minutes.

The obtained coated plate was allowed to stand in a desiccator for 30 minutes, and then the high solid base paint (manufactured by Nippon Paint Co., Ltd.) was coated and set in the same manner as above, and the above-mentioned clear film was applied on the coated film. The coating composition was painted and set up as above and baked at 120 ° C for 30 minutes.

On the surface of the formed coating film, a cutter knife is used.
Using (NT Cutter S type or A type), insert a cross cut of 11 vertical x 11 horizontal with a spacing of 2 mm to penetrate the coating and reach the base of the coated plate, and make 100 squares on the coating. Formed.
A cellophane adhesive tape having a width of 24 mm (manufactured by Nichiban Co., Ltd.) was evenly pressed onto the cross-cut coating film with fingertips so that air bubbles were not generated. Immediately, one end of the pressure-sensitive adhesive tape was held, and the pressure-sensitive adhesive tape was peeled off from the surface of the coating film by abruptly pulling perpendicularly to the surface of the coating film. The adhesion of the coating film was evaluated under the following criteria based on the area ratio of the coating film peeled off together with the adhesive tape.

[0173]

Examples 2 to 15 and 18 to 22 A clear paint was prepared in the same manner as in Example 1 except that the formulations shown in Tables 6 and 7 below were used, and the coating film performance was evaluated. The evaluation results are shown in Tables 6 and 7.

In Example 15, "F-244-09" manufactured by Nippon Unicar Co., Ltd. was used as the silicone polymer (d) -1. In the formula (II), R ¹ is a methyl group, R ² is a γ-glycidoxypropyl group / (trimethoxysilyl) ethyl group = 2/1,
R ³ , R ⁴ , R ⁵ , and R ⁶ are methyl groups, l = 6, m = 2, n = 0, epoxy equivalent 318, and alkoxy equivalent 213.

Further, in Example 19, as polyepoxide (c) -6, "Denacol EX-314" manufactured by Nagase Kasei Kogyo Co., Ltd.
(Glycidyl ether type epoxy resin of glycerin, epoxy equivalent 145) was used.

Comparative Examples 1 to 3 A clear coating composition was prepared in the same manner as in Example 1 except that the formulations shown in Table 7 below were used, and the coating film performance was evaluated. The evaluation results are shown in Table 7.

Comparative Example 4 A clear paint was prepared in the same manner as in Example 1 except that a high solid type melamine paint manufactured by Nippon Paint Co., Ltd. having the composition shown in Table 5 below was used as a clear paint composition. The performance was evaluated. The evaluation results are shown in Table 7.

[0179]

[Table 5] Blended resin part Acrylic resin manufactured by Nippon Paint Co., Ltd. 75 (nonvolatile content 80%, hydroxyl value 100, acid value 10 and number average molecular weight 1800) Melamine resin "Cymel 303" 20 manufactured by Mitsui Cytec Co., Ltd. 20 (nonvolatile content 100% ) Mitsui Toatsu's melamine resin "Uban 120" 22 (90% non-volatile content) paratoluenesulfonic acid / diisopropanolamine = 1/1 1.8 Ciba-Geigy UV absorber "Tinuvin 900" 2 Sankyo light stabilization Agent "Sanol LS-440" 1 Surface modifier "Modaflow" manufactured by Monsanto 0.1 Aromatic hydrocarbon solvent "Solvesso 100" manufactured by Shell 10

Examples 16 and 17 First, a clear coating composition was obtained in the same manner as in Example 1 except that the formulations shown in Table 7 were used.

On the other hand, a 0.8 mm thick phosphoric acid-treated steel sheet was coated with electrodeposition paint (Power Top U-50 made by Nippon Paint Co., Ltd.) and intermediate coating (Olga P-2 made by Nippon Paint Co., Ltd.) to dry thickness. An aqueous base paint (Example 1 of US Pat. No. 5,183,504) was applied to a process test plate coated so as to have a thickness of 25 μm and 40 μm so as to have a dry film thickness of 15 μm, and the coated film was dried at 80 ° C. for 5 minutes.
A base coating film was formed by drying for a minute.

On top of that, the obtained clear coating composition was added,
Use an electrostatic coating machine (“Auto REA” manufactured by Randsburg Gemma) to apply a spraying pressure of 5 kg / cm ² to a dry film thickness of approximately 40 μm, set for approximately 7 minutes, and then set at 140 ° C. for 25 minutes. Baked for a minute.

The above water-based paint was blended in such a manner that the number average molecular weight obtained in Preparation Example 1 of the same document was 12000 and the hydroxyl value was 7
0, acid value 58 and non-volatile content 50% acrylic resin varnish 56.
Part 2, Mitsui Cytec's methylated melamine "Cymel 30
3 "15.0 parts, acid value 16.2 and urethane content of 33% non-volatile content 21.5 parts, Toyo Aluminum Co., Ltd. aluminum flake content 65% aluminum pigment paste" Alpaste 7 "
160N "7.5 parts and 1.0 part isostearic acid phosphate" Phophorex A-180L "manufactured by Sakai Chemical Co., Ltd.

The performance of the obtained coating film was evaluated in the same manner as in Example 1. The evaluation results are shown in Table 7.

[0185]

[Table 6]

¹ "Denacol EX-314" manufactured by Nagase Kasei Co., Ltd. ² "F-244-09" manufactured by Nippon Unicar Co., Ltd.

[0187]

[Table 7]

¹ “Denacol EX-314” manufactured by Nagase Kasei Co., Ltd. ² “F-244-09” manufactured by Nippon Unicar ³ High solid melamine paint manufactured by Nippon Paint Co., Ltd.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Internal reference number FI Technical display location C09D 163/00 PKE C09D 163/00 PKE PKL PKL (72) Inventor Masanobu Inoue Ikedanaka-cho, Neyagawa-shi, Osaka No. 19-17, Japan Paint Co., Ltd. (72) Inventor Yoshio Eguchi No. 19-17, Ikedanaka-cho, Neyagawa-shi, Osaka Japan Paint Co., Ltd.

Claims (12)

[Claims] 1. An acrylic polycarboxylic acid having (a) an average of two or more carboxyl groups in one molecule, an acid value of 5 to 300 mg KOH / g (solid content) and a number average molecular weight of 500 to 8000.
% By weight; (b) Acid value 50 obtained by reacting a polyester polyol having 3 or more hydroxyl groups with an acid anhydride group-containing compound
-350 mg KOH / g (solid content), polyester polycarboxylic acid having a number average molecular weight of 400 to 3500 and a weight average molecular weight / number average molecular weight of 1.8 or less 5 to 70% by weight; and (c) epoxy equivalent 50 to 700 and number average molecular weight 200 to 10,000
10-80% by weight of a polyepoxide having a high solid content curable resin composition (provided that the amount of components (a) to (c) is based on the weight of all solids in the curable resin composition. Yes.). 2. The polycarboxylic acid (a) comprises 5 to 80% by weight of a carboxyl group-containing ethylenically unsaturated monomer and 20 to 95 ethylenically unsaturated monomer having no carboxyl group.
The curable resin composition according to claim 1, which is obtained by copolymerizing the resin composition with 1% by weight. 3. The polycarboxylic acid (a) comprises 15 to 40% by weight of (a) (i) (1) acid anhydride group-containing ethylenically unsaturated monomer.
(2) Ethylenically unsaturated monomer having no acid anhydride group 60
~ 85% by weight of an acrylic polyanhydride obtained by copolymerizing with, (ii) a monoalcohol having 1 to 12 carbon atoms, the acid anhydride group and the hydroxyl group in a molar ratio.
The curable resin composition according to claim 1, which is an acrylic polycarboxylic acid having a carboxyl group and a carboxylic acid ester group, which is obtained by reacting in an amount of 1/10 to 1/1. 4. The polyepoxide (c) has the formula (c) (i). [Wherein R is a hydrogen atom or a methyl group, and X is (In the formula, Y is a linear or branched alkylene group having 2 to 8 carbon atoms, m is an integer of 3 to 7, and q is an integer of 0 to 4.), or ,formula (In the formula, R is a hydrogen atom or a methyl group, and n is 2 to 50.
Is an integer. ) Is an organic chain. ] 5 to 70% by weight of a hydroxyl group-containing ethylenically unsaturated monomer having the structure shown in (ii) and (ii) an epoxy group-containing ethylenically unsaturated monomer 10 to
A polyepoxide having a hydroxyl group and an epoxy group, which is obtained by copolymerizing 60% by weight and (iii) 0 to 85% by weight of an ethylenically unsaturated monomer which does not share both a hydroxyl group and an epoxy group as necessary. Item 1. The curable resin composition according to item 1. 5. The curable resin composition according to claim 1, wherein all the carboxyl groups of the polyester polycarboxylic acid are terminal carboxyl groups. 6. The polyester polyol is obtained by ring-opening addition of a lactone compound having 4 to 7 carbon atoms to a low molecular weight polyhydric alcohol having 3 to 16 carbon atoms and having 3 to 16 carbon atoms to extend the chain. The curable resin composition according to claim 1. 7. The low molecular weight polyhydric alcohol is selected from the group consisting of trimethylolpropane, trimethylolethane, 1,2,4-butanetriol, ditrimethylolpropane, pentaerythritol and dipentaerythritol. The curable resin composition described. 8. The curable resin composition according to claim 6, wherein the lactone compound is selected from the group consisting of ε-caprolactone, γ-caprolactone, γ-valerolactone, δ-valerolactone and γ-butyrolactone. 9. A clear coating composition containing the curable resin composition according to claim 1 as a binder component. 10. The method according to claim 9, further comprising crosslinked resin particles.
The clear coating composition described. 11. A step of applying a water-based or solvent-based base coating on an undercoated or intermediate-coated substrate; a step of applying the clear coating composition according to claim 9 on the base coating without curing the base coating. And a step of curing the base coating film and the clear coating film by heating; 12. A coated article obtained by the method according to claim 11.