JP3212718B2 - Curable composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to curable compositions.
More specifically, the present invention relates to a curable composition which can be suitably used as a resin composition for a top coat used in, for example, architectural exteriors, automobiles, industrial machines, steel furniture, household appliances, plastics and the like.

[0002]

2. Description of the Related Art As thermosetting paints conventionally used, paints of alkyd melamine, acrylic melamine, epoxy melamine type and the like are known. In these, melamine was used as a crosslinking agent, and the odor problem was left unsolved.

[0003] In order to solve the above-mentioned problem, a cross-linking method using a polyol resin and a hydrolyzable silyl group-containing resin is used, which is completely different from the cross-linking method in the conventional melamine-based paint. Paints with excellent properties and solvent resistance have been found, and a patent application (Japanese Unexamined Patent Publication No.
No. 4,1952).

[0004] However, a mixture of a polyol resin and a resin containing a hydrolyzable silyl group has a drawback that if there is a large difference in the glass transition temperature of each resin, the compatibility is poor.

The inventors of the present invention have conducted intensive studies to solve this problem, and as a result, by synthesizing an alkoxysilyl group-containing acrylic copolymer in the presence of an acrylic resin having a hydroxyl group, the compatibility of the problem has been reduced. It has been found that no resin composition can be obtained. When the above resin composition is used, an acrylic resin having a hydroxyl group and an acrylic copolymer having an alkoxysilyl group are mixed at room temperature to obtain a material having better physical properties.

[0006]

The present invention relates to (A) an acrylic resin having a hydroxyl group and an alkyl alcohol, and (B) a compound represented by the following general formula:

[0007]

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Wherein R ¹ is an alkyl group having 1 to 10 carbon atoms, and R ² is a hydrogen atom or a monovalent carbon atom selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, an aryl group and an aralkyl group. Hydrogen group, a represents 0, 1 or 2) 1 to 80% by weight of a vinyl monomer containing a group represented by the following formula:
And alkoxysilyl group-containing acrylic copolymer obtained by radically copolymerizing 99 to 20% by weight of another vinyl monomer
A curable composition comprising:

[0009]

DETAILED DESCRIPTION OF THE INVENTION The acrylic resin having a hydroxyl group as the component (A) used in the present invention (hereinafter, also referred to as the hydroxyl group-containing acrylic resin (A) or simply as the component (A)) has a hardness immediately after baking and a solvent resistance. This is for exhibiting the properties of the coating film such as properties, and the main chain is substantially composed of an acrylic copolymer chain, so that the cured product has good weather resistance, chemical resistance, water resistance, and the like.

The acrylic resin (A) having a hydroxyl group can be obtained, for example, by mixing a hydroxyl-containing vinyl polymerizable compound with acrylic acid,
It can be obtained by copolymerization with methacrylic acid or a derivative thereof.

Examples of the hydroxyl-containing vinyl polymerizable compound include 2-hydroxyethyl (meth) acrylate, 1-hydroxypropyl (meth) acrylate,
2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl vinyl ether, N-methylol (meth) acrylamide, Alonix 5700, 4-hydroxystyrene manufactured by Toagosei Chemical Industry Co., Ltd., HE manufactured by Nippon Shokubai Chemical Industry Co., Ltd. -10, HE-20, HP-10
And HP-20 (each an acrylate oligomer having a hydroxyl group at a terminal), Blenmer PP series (polypropylene glycol methacrylate), Blenmer PE series (polyethylene glycol monomethacrylate), Blenmer PEP series (polyethylene glycol) manufactured by NOF Corporation Polypropylene glycol methacrylate), Blemmer AP-400 (polypropylene glycol monoacrylate), Blemmer A
E-350 (polyethylene glycol monoacrylate), Blemmer NKH-5050 (polypropylene glycol polytrimethylene monoacrylate) and Blemmer-GLM (glycerol monomethacrylate),
Ε-caprolactone-modified hydroxyalkyl vinyl monomers obtained by reacting a hydroxyl group-containing vinyl compound with ε-caprolactone. Above all,
By using an ε-caprolactone-modified hydroxyalkylvinyl-based monomer, the impact resistance and flexibility of the coating film can be improved.

Representative examples of the ε-caprolactone-modified hydroxyalkylvinyl monomer include, for example,

[0013]

[0014] da Iseru Chemical Industrial Co., Ltd. Placce
l FA- 1, Placel FA- 4, Placc
el FM- 1 Contact and Placce1 FM- 4, UC
C (Ltd.) of TONE M-10 0 Contact and TONE M
Etc. -20 of 1, and the like.

These hydroxyl group-containing vinyl polymerizable compounds may be used alone or in combination of two or more.

The acrylic acid or methacrylic acid derivative copolymerizable with the hydroxyl group-containing vinyl polymerizable compound is not particularly limited, and specific examples thereof include, for example, methyl (meth) acrylate, ethyl (meth) acrylate,
n-butyl (meth) acrylate, isobutyl methacrylate, 2-ethylhexyl (meth) acrylate, stearyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, trifluoroethyl (meth) acrylate, pentafluoropropyl (meth) ) Acrylate, perfluorocyclohexyl (meth) acrylate, (meth) acrylonitrile, glycidyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth) acrylamide, α-
Ethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N, N-dimethylacrylamide, N-methylacrylamide, acryloylmorpholine, N-methylol (meth) acrylamide, a macromonomer manufactured by Toa Gosei Chemical Industry Co., Ltd. A certain AS-6,
Α, such as AN-6, AA-6, AB-6, AK-5, and hydroxylalkyl esters of (meth) acrylic acid;
Phosphoric acid ester group-containing vinyl compounds, which are condensation products of hydroxyalkyl esters of β-ethylenically unsaturated carboxylic acids and phosphoric acid or phosphoric acid esters, and (meth) acrylates containing urethane bonds or siloxane bonds. Can be

The component (A) may contain a segment formed by a urethane bond or a siloxane bond in the main chain within a range not exceeding 50% (% by weight, the same applies hereinafter). A segment derived from a monomer other than the acid derivative may be included. This monomer is not limited, and specific examples thereof include styrene and α.
-Aromatic hydrocarbon vinyl compounds such as methylstyrene, chlorostyrene, styrenesulfonic acid and vinyltoluene; unsaturated carboxylic acids such as maleic acid, fumaric acid and itaconic acid, and salts thereof (alkali metal salts, ammonium salts, Esters of unsaturated carboxylic acids such as amine salts), their anhydrides (such as maleic anhydride), or diesters or half-esters thereof with linear or branched alcohols having 1 to 20 carbon atoms; vinyl acetate ,
Vinyl esters and allyl compounds such as vinyl propionate and diallyl phthalate; vinyl compounds containing amino groups such as vinyl pyridine and aminoethyl vinyl ether;
Amide group-containing vinyl compounds such as itaconic acid diamide, crotonamide, maleic acid diamide, fumaric acid diamide, N-vinylpyrrolidone; methyl vinyl ether;
Other vinyl compounds such as cyclohexyl vinyl ether, vinyl chloride, vinylidene chloride, chloroprene, propylene, butadiene, isoprene, fluoroolefin maleimide, N-vinylimidazole, and vinyl sulfonic acid.

The component (A) is synthesized by a solution polymerization method using a peroxide radical initiator such as t-butyl peroxyacetate or an azo radical initiator such as azobisisobutyronitrile. Is preferred in terms of ease of synthesis.

In the solution polymerization method, n-
Dodecyl mercaptan, t-dodecyl mercaptan, n
The molecular weight can be adjusted using a chain transfer agent such as -butyl mercaptan.

As the polymerization solvent used, (A)
It is preferable to use alkyl alcohols from the viewpoint of preventing gelation when the component (B) is polymerized in the component and the storage stability thereafter.

The alkyl alcohols are preferably those having an alkyl group having 1 to 10 carbon atoms, for example, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, s-butyl. alcohol,
t-Butyl alcohol, n-amyl alcohol, isoamyl alcohol, hexyl alcohol, octyl alcohol, cellosolve and the like are used. In particular, when methyl alcohol is used, the above effect is large and preferable.

The amount of the alkyl alcohol to be used is preferably 3 parts (parts by weight, hereinafter the same) to 100 parts, and more preferably 5 parts to 50 parts per 100 parts of the resin solid content of the component (A).
Parts are more preferred. If the amount is less than 3 parts, the effect on gelation prevention and storage stability is low, and if it exceeds 100 parts, there is a possibility that problems may occur in workability when used as a paint.

The alkyl alcohol may be added after the polymerization.

Further, an acrylic resin having a hydroxyl group (A)
May be a non-aqueous dispersion type in which polymer particles insoluble in a non-polar organic solvent such as heptane and pentane are dispersed.

The molecular weight and hydroxyl value of the acrylic resin (A) having a hydroxyl group are not particularly limited, but the number average molecular weight is preferably from 1,500 to 40,000.
It is more preferably from 3,000 to 25,000 from the viewpoint of physical properties of a coating film formed from the composition of the present invention such as durability. Further, it is necessary to have a sufficient number of hydroxyl groups capable of crosslinking, and the hydroxyl value is 10 to 300 mg KO.
H / g, preferably 30 to 150 mg KOH /
g is more preferable from the viewpoint of physical properties of the coating film such as strength and durability.

The acrylic resin (A) having a hydroxyl group may be used alone or in combination of two or more.

The composition of the present invention has the following general formula, which becomes the component (B) in the presence of the component (A) and the alkyl alcohol:

[0028]

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A radical copolymer of 1 to 80 % of a vinyl monomer containing a group represented by the formula and 99 to 20 % of another vinyl monomer.

The copolymerization of the monomer as the component (B) in the presence of the component (A) and the alkyl alcohol means that the component (B) is polymerized in the acrylic resin (A) and the alkyl alcohol. This means that a vinyl monomer and an initiator are added and radical copolymerization is performed. In this manner, a component is produced when the components (A) and (B) are copolymerized independently and then mixed. Compatibility imperfections can be improved.

The general formula for the component (B):

[0032]

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The use ratio of the vinyl monomer represented by the formula is 1 to 80%, preferably 3 to 70%, while the use ratio of the other vinyl monomer is 99 to 20%, preferably 97 to 30%. The use range is preferable,
This is because the curability of the composition and the durability of the coating film are excellent.

The alkoxysilyl group-containing acrylic copolymer (B) of the component (B) obtained by the above-mentioned copolymerization (hereinafter also referred to as the alkoxysilyl group-containing acrylic copolymer (B) or simply as the component (B)) is as described above. It is a polymer having at least one, preferably two or more alkoxysilyl groups represented by the formula in one molecule. This alkoxysilyl group may be contained at the terminal of the main chain of the component (B), may be contained in a side chain, or may be contained in both.

If the number of alkoxysilyl groups in one molecule of the component (B) is less than 1, the solvent resistance of the coating film obtained from the composition of the present invention tends to decrease.

In the above formula, R ¹ is an alkyl group having 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms. When the number of carbon atoms exceeds 10, the reactivity of the alkoxysilyl group decreases, and the reactivity also decreases when R ¹ is other than an alkyl group, for example, a phenyl group or a benzyl group.

Specific examples of R ¹ include, for example, methyl, ethyl, n-propylene, isopropyl, n
-Butyl group, isobutyl group and the like.

In the above formula, R ² is a hydrogen atom, having 1 to 1 carbon atoms.
0, preferably a monovalent hydrocarbon group selected from the group consisting of 1 to 4 alkyl groups, aryl groups and aralkyl groups.

Specific examples of the alkyl group as R ² include:
It mentioned the same groups as R ^1, specific examples of the aryl group, for example, a phenyl group, and specific examples of the aralkyl groups, such as benzyl group.

In the formula, a represents 0, 1 or 2.

Specific examples of the alkoxysilyl group represented by the above general formula include, for example, groups contained in an alkoxysilyl group-containing monomer described later.

The alkoxysil group-containing acrylic copolymer (B) is excellent in weather resistance, chemical resistance, water resistance, etc. of the cured product since the main chain is substantially composed of an acrylic copolymer chain. Further, since the alkoxysilyl group is bonded to the carbon atom, the cured product is excellent in water resistance, alkali resistance, acid resistance and the like.

The number average molecular weight of the alkoxysilyl group-containing acrylic copolymer (B) is from 1,000 to 30,0 in view of physical properties such as durability of a coating film obtained from the composition of the present invention.
00 is preferable, and 3,000 to 25,000 is more preferable.

The component (B) can be obtained, for example, by copolymerizing acrylic acid, methacrylic acid, a derivative thereof and the like with an alkoxysilyl group-containing monomer.

The derivative of acrylic acid or methacrylic acid is not limited, and specific examples thereof include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and 2-ethylhexyl (meth) acrylate. ) Acrylate, stearyl (meth) acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, trifluoroethyl (meth) acrylate, pentafluoropropyl (meth) acrylate, perfluorocyclohexyl (meth) acrylate, (meth) acrylonitrile, Glycidyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth) acrylamide, α-ethyl (meth) acrylamide, N-but Cimethyl (meth) acrylamide, N, N-dimethylacrylamide, N-methylacrylamide, acryloylmorpholine, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, N-methylol (meth) acrylamide, Toa Gosei Chemical Aronix M- manufactured by Kogyo Co., Ltd.
5700, AS-6, AN-6, AA-6, AB-6, AK which are macromonomers manufactured by Toa Gosei Chemical Industry Co., Ltd.
-5, Placel F manufactured by Daicel Chemical Industries, Ltd.
A-1, Placel FA-4, Placel
A condensation product of a hydroxyalkyl ester of an α, β-ethylenically unsaturated carboxylic acid, such as FM-1, FM FM-1 or a hydroxyalkyl ester of (meth) acrylic acid, with a phosphoric acid or a phosphoric acid ester; Examples include a phosphoric ester group-containing vinyl compound and a (meth) acrylate containing a urethane bond or a siloxane bond.

The alkoxysilyl group-containing monomer is not particularly limited except that it has a polymerizable double bond, and specific examples thereof include, for example,

[0047]

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Examples thereof include (meth) acrylates having an alkoxysilyl group at the terminal via a urethane bond or a siloxane bond.

The proportion of the alkoxysilyl group-containing monomer in the component (B) is preferably from 1 to 80%, more preferably from 3 to 70%, in view of the curability of the composition and the durability of the coating film.

The component (B) may contain a segment formed by a urethane bond or a siloxane bond in the main chain within a range not exceeding 50%, and may be derived from a monomer other than the (meth) acrylic acid derivative. May be included. The monomer is not limited, and specific examples thereof include aromatic hydrocarbon vinyl compounds such as styrene, α-methylstyrene, chlorostyrene, styrenesulfonic acid, 4-hydroxystyrene, and vinyltoluene; Acids, unsaturated carboxylic acids such as itaconic acid, salts thereof (alkali metal salts, ammonium salts, amine salts, etc.), their acid anhydrides (maleic anhydride, etc.), or those having 1 to 20 carbon atoms. Esters of unsaturated carboxylic acids such as diesters or half esters with chain or branched alcohols; Vinyl esters and allyl compounds such as vinyl acetate, vinyl propionate and diallyl phthalate; Vinyl groups containing amino groups such as vinyl pyridine and aminoethyl vinyl ether Compound; Itaconic acid diamide, Croto Amide, maleic diamide, fumaric diamide, N-vinylpyrrolidone and other amide group-containing vinyl compounds; 2-hydroxyethyl vinyl ether, methyl vinyl ether, cyclohexyl vinyl ether, vinyl chloride, vinylidene chloride, chloroprene, propylene, butadiene, isoprene, fluoro Other vinyl compounds such as olefin maleimide, N-vinyl imidazole, vinyl sulfonic acid and the like can be mentioned.

The alkoxysilyl group-containing acrylic copolymer (B) can be prepared by the same method as described in, for example, JP-A-54-36395, JP-A-57-36109, and JP-A-58-157810. Although it can be produced in the presence of the component (A), it is most preferably produced by a solution polymerization method using an azo radical initiator such as azobisisobutyronitrile from the viewpoint of ease of synthesis.

In this case, if necessary, n-dodecyl mercaptan, t-dodecyl mercaptan, n-butyl mercaptan, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane ,
The molecular weight can be adjusted by using a chain transfer agent such as γ-mercaptopropylmethyldiethoxysilane and (CH ₃ O) ₃ Si-SS-Si (OCH ₃ ) ₃ . In particular, it is preferable to use a chain transfer agent having an alkoxysilyl group in the molecule, for example, γ-mercaptopropyltrimethoxysilane, because the alkoxysilyl group can be introduced into the terminal of the silyl group-containing acrylic copolymer.

The polymerization solvent used in the solution polymerization method includes hydrocarbons (toluene, xylene, n-hexane, cyclohexane, etc.), acetates (ethyl acetate, butyl acetate, etc.), alcohols (methanol, ethanol, etc.). , Isopropanol, n-butanol, etc.),
Non-reactive solvents such as ethers (ethyl cellosolve, butyl cellosolve, cellosolve acetate, etc.) and ketones (methyl ethyl ketone, ethyl acetoacetate, acetylacetone, diacetone alcohol, methyl isobutyl ketone, acetone, etc.) are not particularly limited.

The proportion of the alkoxysilyl group-containing polymer (B) to be used is not particularly limited, but the weight ratio of component (A) / component (B) is preferably 9/1 to 1/9, and 8/2 to 2/9. / 8
Is more preferred. When the ratio of the component (A) / component (B) exceeds 9/1, the water resistance of the coating film obtained from the composition of the present invention tends to decrease. There is a tendency for the characteristics to be blended to be insufficient.

The composition of the present invention usually contains a solvent, but the solvent used is not particularly limited as long as it is non-reactive.

Specific examples of such solvents include aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, alkyl alcohols, and ketones used in general paints and coating agents. , Esters, ethers, alcohol esters, ketone alcohols, ether alcohols, ketone ethers, ketone esters, ester ethers, and the like, in that the storage stability of the composition is improved, Alkyl alcohols are preferred.

As the alkyl alcohol, those having 1 to 10 carbon atoms in the alkyl group are preferable. For example, methyl alcohol, ethyl alcohol, n-propyl alcohol, isopropyl alcohol, n-butyl alcohol, isobutyl alcohol, s-butyl alcohol , T
-Butyl alcohol, n-amyl alcohol, isoamyl alcohol, hexyl alcohol, octyl alcohol, cellosolve and the like are used. The amount of the alcohol used is not particularly limited, but is preferably 100 parts or less, more preferably 50 parts or less, based on 100 parts of the resin solids of the components (A) and (B). The amount of the solvent used depends on the molecular weight or composition of the components (A) and (B), and is adjusted according to the solid content concentration or viscosity required for practical use.

It is preferable to use a dehydrating agent in order to ensure storage stability that does not cause a problem even when used repeatedly over a long period of time.

Specific examples of the dehydrating agent include, for example, methyl orthoformate, ethyl orthoformate, methyl orthoacetate, ethyl orthoacetate, methyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane, methylsilicate, Examples include hydrolyzable ester compounds such as ethyl silicate. The dehydrating agent may be added before the polymerization of the alkoxysilyl group-containing polymer (B), may be added after the polymerization, or may be added during the polymerization.

Although the amount of the dehydrating agent used is not particularly limited,
Usually 100 parts or less is preferable, and 50 parts or less is more preferable with respect to 100 parts of resin solid content of (A) component and (B) component.

When an alkyl alcohol and a dehydrating agent are used in combination, a remarkable effect is observed on the storage stability when the composition of the present invention is stored.

The composition of the present invention thus obtained can be used as a resin composition for coatings, and the obtained cured product is excellent in weather resistance, chemical resistance, solvent resistance and the like. .

Next, the composition of the present invention was prepared based on Examples.
This will be described more specifically.

Synthesis Example 1 [Synthesis of Hydroxyl-Containing Acrylic Resin (A)]
A reaction vessel equipped with a thermometer, a reflux condenser, a nitrogen gas inlet tube and a dropping funnel was charged with 36.0 parts of xylene,
After the temperature was raised to 110 ° C. while introducing nitrogen gas, a mixture (c) having the following composition was dropped at a constant rate over 5 hours using a dropping funnel.

Mixture (c) Toluene 20.7 parts Styrene 36.7 parts N-butyl acrylate 33.2 parts Placcel FM-4 ^{* 1} 30.1 parts 2,2′-azobisisobutyronitrile 0.9 [Note] * 1: Methacrylic acid 2 manufactured by Daicel Chemical Industries, Ltd.
-Hydroxyethyl / ε-caprolactone reaction mixture After completion of the dropwise addition of the mixture (c), 0.1 part of 2,2'-azobisisobutyronitrile and 10.0 parts of toluene were added dropwise over 1 hour.

After completion of the dropwise addition, the mixture was reacted at 110 ° C. for 2 hours and cooled, and 10 parts of methanol and xylene were added to the resin solution to adjust the solid concentration to 50%.

Synthesis Example 2 [Synthesis of alkoxysilyl group-containing acrylic copolymer (B)] In the same reaction vessel as in Synthesis Example 1, 20 parts of (A) obtained in Synthesis Example 1 and 41.0 parts of xylene were charged. After the temperature was raised to 110 ° C. while introducing nitrogen gas, a mixture (d) having the following composition was dropped at a constant rate over 5 hours using a dropping funnel.

Mixture (d) Styrene 10.7 parts Methyl methacrylate 74.0 parts n-methylolacrylamide 0.9 parts γ-methacryloxypropyl trimethoxysilane 15.2 parts Toluene 10.5 parts 2,2′-azo 2.6 parts of bisisobutyronitrile After the completion of the dropwise addition of the mixture (d), 0.3 parts of 2,2'-azobisisobutyronitrile and 16 parts of toluene were added dropwise at a constant speed over 1 hour. After completion of the dropwise addition, the mixture was aged at 110 ° C. for 2 hours and then cooled, and xylene was added to the resin solution to adjust the solid concentration to 50%.

Examples 1-2 and Comparative Examples 1-2 The resin solution obtained by synthesizing the component (B) in the component (A) obtained in the synthesis example 2 and the components (A) and (B) alone were used alone. Compatible with the resin solution synthesized and mixed at room temperature,
Table 1 shows the results of comparison of curability and solvent resistance.

For compatibility, the resin solution was spread on a glass plate, and the transparency was visually evaluated after the solvent was volatilized at 50 ° C. × 2 hours. For the curability, an effect catalyst was manufactured by Sakai Chemical Industry Co., Ltd. TN801 (tin compound) of 1% based on the resin solid content, painted with an applicator,
The coating was baked at 0 ° C. for 150 minutes to form a coating film of about 40 μm, and the gel fraction after immersion in acetone for 24 hours was measured and evaluated. The solvent resistance was evaluated by rubbing the coating film prepared in the same manner as above with gauze impregnated with xylene, and evaluating the number of times until the scratch was formed.

Table 1 shows the results.

[0072]

[Table 1]

Examples 3-4 and Comparative Examples 3-4 When the acrylic resin having a hydroxyl group obtained in Synthesis Example 1 was used with or without 10% of an alkyl alcohol as a solvent, the content of component (A) was reduced. Then, the storage stability at 50 ° C. × 1 month when the component (B) was synthesized was examined.

Table 2 shows the results.

[0075]

[Table 2]

[0076]

According to the present invention, a resin having a poor compatibility can be obtained in a compatible state, and the curability is excellent. The cured product also has excellent solvent resistance.

Claims (3)

(57) [Claims] (1) In the presence of (A) an acrylic resin having a hydroxyl group and an alkyl alcohol, (B) a general formula: (Wherein, R ¹ is an alkyl group having 1 to 10 carbon atoms, R ² is a hydrogen atom or a monovalent hydrocarbon group selected from the group consisting of an alkyl group having 1 to 10 carbon atoms, an aryl group and an aralkyl group; a is a vinyl monomer 1-80% by weight, and other vinyl monomer 99 to 20% by weight containing a group represented by 0, 1 or 2) by radical copolymerization al
A curable composition comprising a coxysilyl group-containing acrylic copolymer . 2. The curable composition according to claim 1, wherein the acrylic resin as the component (A) has a hydroxyl value of 10 to 300 mgKOH / g and a number average molecular weight of 1,500 to 40,000. 3. The curable composition according to claim 1, wherein the solvent for the acrylic resin as the component (A) contains 3 to 100 parts by weight of an alkyl alcohol per 100 parts by weight of the resin solid content.