JP3385372B2 - Curable composition for top coat - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a curable composition for top coatings, and more specifically, metal, ceramics, glass, cement, ceramic moldings, plastics, wood, paper, textiles, building exteriors, home appliances, industry. The present invention relates to a curable composition for a top coating used in machines and the like.

[0002]

2. Description of the Related Art Conventionally, by coating the surface of industrial products such as ceramic materials, steel, construction and building materials with a paint, the design effect can be enhanced and the weather resistance and corrosion resistance can be improved. It exhibits excellent functions such as improving the. For example, a high weather resistance resin paint such as a fluororesin paint, an acrylic urethane resin paint or a hydrolyzable silyl group-containing acrylic resin (acrylic silicone resin) paint is applied to improve physical properties such as weather resistance and corrosion resistance.

By the way, in recent years, there has been a demand for improvement of pollution resistance as the environment deteriorates mainly in urban areas. Even in the paint industry, top coat paints with excellent stain resistance have been demanded without exception. In the above-mentioned high weather resistance resin coating, since it has excellent weather resistance and durability, it is necessary that it is also excellent in stain resistance, but in general, the high weather resistance resin coating is satisfactory. It does not have stain resistance. It should be noted that the acrylic silicone resin paint is superior to other paints in terms of anti-staining property because of its charging characteristics, but it is still insufficient.

The present invention is a curable composition for a topcoat paint, which has succeeded in improving stain resistance while maintaining the high weather resistance, corrosion resistance, designability and the like which are characteristics of acrylic silicone resin.

That is, as described above, the cured product of the acrylic silicone resin has excellent stain resistance as compared with the existing acrylic urethane resin paint and fluororesin paint, but it meets the market needs. As a result of repeated studies aimed at obtaining as high a contamination resistance as possible, it was found that the combined use with a silicon compound such as tetraalkoxysilane or methyltrialkoxysilane is effective, and the application has been filed previously.

However, when the above-mentioned silicon compound is added to improve the stain resistance, the compatibility with the acrylic silicone resin may be deteriorated and the physical properties such as appearance may be impaired if the addition amount exceeds a certain limit. Therefore, the amount of the silicon compound cannot be increased by a certain amount or more, and there is a problem that the antifouling performance cannot be sufficiently imparted.

On the other hand, the compatibility between the acrylic silicone resin and the silicon compound can be improved by allowing the resin obtained by hydrolyzing and condensing the above silicone compound to acryl silicone resin to be present in the coating system as a compatibilizer. It was possible to improve the stain resistance improvement level.

[0008]

The present invention is to increase the hydrophobicity of the coating surface and suppress filming and skinning by using an aliphatic hydrocarbon as a polymerization or diluting solvent. That is, the resin obtained by hydrolytically condensing a silicon compound is present in an acrylic resin to improve the compatibility of the coating system when the silicate compound is added, and to improve the stain resistance improvement level.

The curable composition for top-coat paint of the present invention is (A) General formula

[Chemical 3] (In the formula, R ¹ is an alkyl group having 1 to 10 carbon atoms or a phenyl group, 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, a represents 0, 1 or 2 , and contains an alkoxysilyl group bonded to a carbon atom and does not contain a siloxane bond (hereinafter, referred to as “alkoxysilyl group-containing acrylic copolymer”). Polymer (A) "or simply" (A) component ") 100
Parts (parts by weight, the same applies hereinafter) (B) General formula

[Chemical 4] (Wherein R ³ is an alkyl group having 1 to 10 carbon atoms, R ⁴ is an alkyl group having 1 to 10 carbon atoms, a phenyl group or an alkoxy group, and a is 0, 1 or 2) Alternatively, a partial hydrolysis-condensation product thereof (hereinafter, also simply referred to as “(B) component”) 2 to 70 parts (C) 5 to 90 parts of the (B) component is condensed to 100 parts of the (A) component. Obtained alkoxysilyl group-containing acrylic copolymer (hereinafter, also referred to as "alkoxysilyl group-containing acrylic copolymer (C)" or simply "(C) component") 2 to 70 parts (D) curing agent (hereinafter , Also simply referred to as “(D) component”)
It consists of 0.1 to 20 parts.

Component (A) The alkoxysilyl group-containing acrylic copolymer (A) used in the present invention is

[Chemical 5] It is a polymer having at least one, preferably two or more alkoxysilyl groups in each molecule. The alkoxysilyl group may be contained at the end of the main chain of the component (A), may be contained in the side chain, or may be contained in both.

When the number of alkoxysilyl groups in one molecule of the component (A) 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 or a phenyl group. When the number of carbon atoms exceeds 10, the reactivity of the alkoxysilyl group decreases, and when R ¹ is other than an alkyl group or a phenyl group, for example, a benzyl group, the reactivity decreases.

Specific examples of R ¹ include, for example, a methyl group,
Examples thereof include ethyl group, n-propyl group, isopropyl group, n-butyl group and isobutyl group.

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

Specific examples of the alkyl group represented by R ² include:
Include the same groups as R ^1, specific examples of the aryl group, for example, a phenyl group and the like, specific examples of the aralkyl group include benzyl group.

When two or more R ^1's are present, they may be the same or different. Similarly for R ² ,
When two or more are present, they may be the same or different.

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

The alkoxysilyl group-containing acrylic copolymer (A) is excellent in weather resistance, chemical resistance, water resistance and the like of the cured product because its main chain is substantially composed of acrylic copolymer chains. 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 (A) is 1,000 to 30, from the viewpoint of physical properties such as durability of the coating film obtained from the composition of the present invention.
000 is preferable, and 3,000 to 25,000 is more preferable.

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

There is no limitation on the derivative of acrylic acid or methacrylic acid, and specific examples thereof include, for example, methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, and 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, dibutylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth) acrylamide, α-ethyl (meth) acrylamide, N-butoxy Methyl (meth) acrylamide, N, N-dimethylacrylamide, N-methylacrylamide, acryloylmorpholine, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, N-methylol (meth) acrylamide, Toagosei chemistry Aronix M- manufactured by Kogyo Co., Ltd.
5700, AS-6, AN-6, AA-6, AB-6, AK which are macromonomers manufactured by Toagosei Co., Ltd.
-5, PlaccelFA manufactured by Daicel Chemical Industries, Ltd.
-1, Placcel FA-4, Placcel F
M-1, Placcel FM-4, a condensation product of a hydroxyalkyl ester of an α, β-ethylenically unsaturated carboxylic acid such as a hydroxyalkyl ester of (meth) acrylic acid with a phosphoric acid or a phosphoric ester. phosphoric ester group-containing vinyl compounds, urethane binding
(Meth) acrylate containing the like.

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

[Chemical 6]

[0023]

[Chemical 7] And the like, having an alkoxysilyl group at the end through a urethane <br/> binding (meth) acrylates such as are also included.

The proportion of the alkoxysilyl group-containing monomer in the component (A) is preferably 5 to 90%, more preferably 11 to 70%, from the viewpoint of the curability of the composition and the durability of the coating film.

[0025] (A) in the component, not exceeding 50%, the main chain may contain segments that are more formed urethane binding to, derived from a monomer other than (meth) acrylic acid derivatives It may include a segment. The monomer is not limited, and specific examples thereof include aromatic hydrocarbon vinyl compounds such as styrene, α-methylstyrene, chlorostyrene, styrenesulfonic acid, 4-hydroxystyrene, vinyltoluene; maleic acid, fumaric acid. Unsaturated carboxylic acids such as acids and itaconic acid, their salts (alkali metal salts, ammonium salts, amine salts, etc.), their acid anhydrides (maleic anhydride, etc.) Unsaturated carboxylic acid esters such as diesters or half esters with chain or branched alcohols; vinyl acetate and vinyl compounds such as vinyl acetate, vinyl propionate and diallyl phthalate; vinyl group-containing vinyls such as vinyl pyridine and aminoethyl vinyl ether Compounds; itaconic acid diamide, croton Bromide, diamide of maleic acid, fumaric acid diamide, amide group-containing vinyl compounds such as N- vinyl pyrrolidone; 2-hydroxyethyl vinyl ether,
Other vinyl compounds such as methyl vinyl ether, cyclohexyl vinyl ether, vinyl chloride, vinylidene chloride, chloroprene, propylene, butadiene, isoprene, fluoroolefin maleimide, N-vinyl imidazole, vinyl sulfonic acid and the like can be mentioned.

In the present invention, a carboxyl group-containing monomer or its acid anhydride can be used as a method for obtaining a composition having excellent curability.

The alkoxy silyl group-containing acrylic copolymer (A) is disclosed, for example, in JP-A-54-36395.
Although it can be produced by the method shown in JP-A-57-36109 and JP-A-58-157810,
From the viewpoint of easiness of synthesis and the like, it is most preferable to manufacture by a solution polymerization method using an azo radical initiator such as azobisisobutyronitrile.

Also in this case, if necessary, n-dodecyl mercaptan, t-dodecyl mercaptan, n-butyl mercaptan, γ-mercaptopropyltrimethoxysilane, γ-mercaptopropyltriethoxysilane, γ-mercaptopropylmethyldimethoxysilane. ,
γ-mercaptopropylmethyldiethoxysilane, (C
_{H 3 O) 3 Si-S} -S-Si (OCH 3) using a chain transfer agent such as _3, can be prepared molecular weight. Particularly, 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.), acetic acid esters (ethyl acetate, butyl acetate, etc.), ethers (ethyl cellosolve, Butyl cellosolve, cellosolve acetate, etc.),
There is no particular limitation as long as it is a non-reactive solvent such as ketones (methyl ethyl ketone, ethyl acetoacetate, acetylacetone, methyl isobutyl ketone, acetone, etc.).

Such an alkoxysilyl group-containing polymer (A) may be used alone or in combination of two or more.

It should be noted that n-butyl methacrylate is used as a comonomer because of its compatibility with the alkyl silicate (tetraalkoxysilane), trialkoxysilane, dialkoxysilane or its condensate of the component (B) described later.
It is desirable to introduce 0 to 50 parts.

Component (B) Component (B), which is an alkyl silicate (tetraalkoxysilane), trialkoxysilane, dialkoxysilane or a condensate thereof, improves the stain resistance of the coating film to be formed, and improves the stain resistance of the coating film and the substrate. Improves the adhesion of materials.

As such an alkyl silicate,
Examples thereof include tetramethyl silicate (tetramethoxysilane), tetraethyl silicate, tetra-n-propyl silicate, tetra-i-propyl silicate, and tetra-n-butyl silicate.

The reaction for forming a partial condensate obtained by condensing the above tetraalkyl silicate under hydrolysis conditions is as follows:
According to a known manufacturing method. That is, it can be carried out, for example, by adding water to tetraalkyl silicate to cause condensation. Moreover, a commercial item can also be used for the tetraalkyl silicate condensate. Such condensates include MSI51, ESI28, ESI40, H
AS-1, HAS-10 (both are Colcoat Co., Ltd.)
Manufactured by Mitsui Chemicals Co., Ltd., etc., such as methanol silica sol.

As the trialkoxysilane, methyltrimethoxysilane, methyltriethoxysilane,
Phenyltrimethoxysilane, phenyltriethoxysilane, octadecyltriethoxysilane, 3glycidoxypropylmethoxysilane, methyltrisec-octyloxysilane, methyltriphenoxysilane, methyltriisopropoxysilane, methyltributoxysilane and the like, and condensation thereof. You can list things. Moreover, a commercial item can also be used for these condensates.
Examples of such condensates include AFP-1 (Shin-Etsu Chemical).

As the dialkoxysilane, dimethyldimethoxysilane, methylethyldimethoxysilane, diethyldimethoxysilane, methylphenyldimethoxysilane, methylphenyldiethoxysilane, dimethyldisec-octyloxysilane, dimethyldiphenoxysilane, dimethyltriisosilane. Examples include propoxysilane and the like, and condensation products thereof. These may be used alone or as a mixture.

The blending ratio of the above-mentioned component (B) is 2 to 70 with respect to 100 parts of the resin content of the component (A) in order to impart stain resistance.
Parts, preferably 5 to 50 parts. If it is less than 2 parts, the effect of improving the stain resistance of the obtained coating film is not sufficient, and if it exceeds 70 parts, problems such as the appearance of the coating film and cracks occur.

Component (C) The component (C) used in the present invention has the effect of improving the compatibility between the component (A) and the component (B). That is,
When the component (A) and the component (B) are blended, if the amount of the component (B) is large, the compatibility of the composition of the component (A) deteriorates and the appearance of the coating film becomes poor. By blending the component C), such a fear is eliminated. Furthermore, as an effect of adding the component (C), elasticity can be imparted to the coating film, and it is effective in improving stain resistance.

The molecular weight of the component (A) used to obtain the component (C) is not particularly limited, but the number average molecular weight is 1,000 to 30, from the viewpoints of workability, stability, coating appearance and the like. 0
It is about 00, particularly preferably about 3,000 to 15,000. Further, as the silicate component used at the time of condensation, the silicon compound as the component (B) can be used.

The proportion of the component (C) added to the coating system depends on the compatibility of the silicon compound with the component (A) component 1.
It is 2 to 70 parts, preferably 5 to 50 parts, relative to 00 parts. If it is less than 2 parts, the effect of improving the compatibility obtained is not sufficient, and if it exceeds 70 parts, problems such as adversely affecting the stability of the paint and the durability of the coating film occur.

Component (D) Specific examples of the curing agent (curing catalyst) that is the component (D) used in the present invention include, for example, dibutyltin dilaurate,
Dibutyltin dimaleate, dioctyltin dilaurate, dibutyltin bisacetylacetonate, dibutyltin diacetate, dibutyltin dioctate, dibutyltin bisethylmalate, dibutyltin bis (2-ethylhexyl) malate, dibutyltin bisoleyl maleate, dibutyltin oxide, dibutyltin bistriethoxy. Organotin compounds such as silicate, dioctyl tin dimaleate, tin octylate; phosphoric acid, monomethyl phosphate, monoethyl phosphate, monobutyl phosphate, monooctyl phosphate, monodecyl phosphate, dimethyl phosphate, diethyl phosphate, dibutyl phosphate, dioctyl phosphate, Phosphoric acid or phosphoric acid ester such as didecyl phosphate; Alkyl ester Phosphates; organoaluminum compounds such as tris (ethylacetoacetate) aluminum, tris (acetylacetonato) aluminum; tetrabutylzirconate, tetrakis (acetylacetonato) zirconium, tetraisobutylzirconate, butoxytris (acetylacetonate) ) Organozirconium compounds such as zirconium; maleic acid, adipic acid, azelaic acid, sebacic acid, itaconic acid, citric acid, succinic acid, phthalic acid, trimellitic acid, pyromellitic acid, their acid anhydrides, paratoluene sulfone Acidic compounds such as acids; amines such as hexylamine, di-2-ethylhexylamine, N, N-dimethyldodecylamine, dodecylamine; mixtures or reaction products of these amines and acidic phosphates; Sodium,
Examples thereof include alkaline compounds such as potassium hydroxide.

Among these curing catalysts, in order to impart stain resistance to the coating film, from the viewpoint of curability, a combination system of phosphoric acid ester and amine, a combination system of organic carboxylic acid and amine, or a dibutyltin compound is used. Is preferred.

Further, when the composition of the present invention is applied on an epoxy coating film which is generally used as an intermediate coating for building materials,
Although the adhesion to the epoxy layer becomes a problem, the composition of the present invention contains aminoethylaminopropyltrimethoxysilane, γ
-Reaction of aminosilane compounds and / or aminosilane compounds such as aminopropyltrimethoxysilane, γ-aminopropyldimethoxysilane aminosilane, γ-aminopropyltriethoxysilane, γ-aminopropyldiethoxysilane with epoxy compounds such as Epicoat 828 When the product is used as an adhesion improver to impart adhesion, it is most preferable to use a dibutyltin-based compound as the curing catalyst.

Such a curing agent (D) may be used alone or in combination of two or more kinds. The amount of the component (D) used is 0.1 to 20 parts, and preferably 0.1 to 10 parts, based on 100 parts of the resin solid content of the components (A) and (B). If the amount of component (D) used is less than 0.1 part, the curability may decrease, and if it exceeds 20 parts, the appearance of the coating film may decrease.

Component (E) Acrylic Copolymer Containing Alkoxysilyl Group (A)
Instead of using, the following component (E) can also be used. That is, the copolymer (E) obtained by polymerizing all the monomers of the component (A) in the presence of the component (B) can be blended instead of the component (A).

As the component (E), as described above,
An alkoxysilyl group-containing acrylic resin obtained by polymerizing the monomer of the component (A) in the presence of the silicon of the component (B). The addition amount of the component (B) is 100 parts of the monomer of the component (A). On the other hand, it is 2 to 70 parts, preferably 5 to 50 parts. If it is less than 2 parts, the effect of improving the compatibility will not be sufficient, and if it exceeds 70 parts, the stability of the resin may be adversely affected. Further, by using (E) instead of (A), the effect of improving the compatibility when a large amount of component (B) is added is exhibited.

The molecular weight of the component (E) is not particularly limited,
From the viewpoint of compatibility, workability, stability, appearance of coating film, etc., the number average molecular weight is about 1,000 to 30,000, particularly preferably about 3,000 to 25,000.

Others It is preferable to use a dehydrating agent and an alkyl alcohol in order to ensure storage stability that does not cause a problem even after repeated use over a long period of time.

Specific examples of the dehydrating agent include methyl orthoformate, ethyl orthoformate, methyl orthoacetate, ethyl orthoacetate, methyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, vinyltrimethoxysilane and methylsilicate. Hydrolyzable ester compounds such as ethyl silicate may be mentioned. Examples of the alkyl alcohol include low molecular weight alcohols such as methanol and ethanol. The dehydrating agent and the alkyl alcohol may be added before the polymerization of the alkoxysilyl group-containing polymer (A), after the polymerization, or during the polymerization.

The amounts of the dehydrating agent and the alkyl alcohol used are not particularly limited, but 0.5 to 20 parts and 2 to 10 parts are more preferable for 100 parts of the resin solid content of the components (A) and (B).

When a dehydrating agent and an alkyl alcohol are used in combination, a remarkable effect on the storage stability can be seen.

In the composition of the present invention, additives such as a diluent, a pigment (including an extender), an ultraviolet absorber, a light stabilizer, an antisettling agent, a leveling agent, etc., depending on the use; nitrocellulose, cellulose acetate. A fibrin such as butyrate; a resin such as an epoxy resin, a melamine resin, a vinyl chloride resin, a chlorinated polypropylene, a chlorinated rubber, polyvinyl butyral; and a filler may be added.

After the above composition is applied to an object to be coated by various methods such as dipping, spraying, brushing, etc., the composition is usually cured at 30 ° C. or higher to give good adhesion and durability to the surface of the object. It is possible to form a coating film having excellent properties.

[0054]

EXAMPLES Next, the curable composition of the present invention will be described more specifically based on examples.

Synthesis of Component (A) Synthesis Example A-1 40 parts of xylene was charged into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas introducing pipe and a dropping funnel.
After the temperature was raised to 110 ° C. while introducing nitrogen gas, the mixture (a) having the following composition was added dropwise at a constant rate over 5 hours by a dropping funnel. Mixture (a) methyl methacrylate 30 parts n-butyl methacrylate 45 parts butyl acrylate 14 parts γ-methacryloxypropyltrimethoxysilane 10 parts acrylamide 1 part xylene 18 parts 2,2-azobisisobutyronitrile 1 part.

After the addition of the mixture (a) was completed, 0.5 parts of 2,2-azobisisobutyronitrile and 8 parts of toluene were added dropwise at a constant rate over 1 hour. After completion of dropping, 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 content concentration to 50%. The number average molecular weight of the obtained resin was 15,000.

Synthesis Example A-2 40 parts of xylene was charged into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas introducing tube and a dropping funnel.
After the temperature was raised to 110 ° C. while introducing nitrogen gas, the mixture (b) having the following composition was added dropwise at a constant rate over 5 hours using a dropping funnel. Mixture (b) Methyl methacrylate 55 parts Butyl acrylate 30 parts γ-methacryloxypropyltrimethoxysilane 10 parts Acrylamide 5 parts Xylene 18 parts 2,2-Azobisisobutyronitrile 1 part.

After the addition of the mixture (b) was completed, 0.5 parts of 2,2-azobisisobutyronitrile and 8 parts of toluene were added dropwise at a constant rate over 1 hour. After completion of dropping, 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 content concentration to 50%. The number average molecular weight of the obtained resin was 15,000.

Synthesis of Component (C) Synthesis Example C-1 42 parts of xylene was charged into a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas introducing pipe and a dropping funnel.
After the temperature was raised to 110 ° C. while introducing nitrogen gas, the mixture (c) having the following composition was added dropwise at a constant rate over 5 hours by a dropping funnel. Mixture (c) Methyl methacrylate 40 parts Butyl acrylate 50 parts γ-methacryloxypropyltrimethoxysilane 10 parts Xylene 10 parts 2,2-Azobisisopropionitrile 6 parts.

After the addition of the mixture (c) was completed, 0.6 part of 2,2-azobisisopropionitrile was dissolved in 18 parts of xylene and added dropwise at a constant rate over 1 hour. 110 after the dropping
After aging for 2 hours at ℃, it was cooled and xylene was added to the resin solution to adjust the solid content to 50%. The number average molecular weight of the obtained resin was 4,000.

Next, the resin obtained above was charged into a reaction vessel, and a small amount of 1.5% HC1 solution and ESI40 (partial condensate of tetraalkoxysilane, Colcoat Co., Ltd.) were used.
25 parts) was added to 100 parts of the resin to carry out hydrolysis condensation.

Synthetic Example C-2 A compatibilizing agent obtained by adding 50 parts of ESI during the hydrolytic condensation reaction of Synthetic Example C-1.

Synthetic Example C-3 A compatibilizer in which n-butyl methacrylate was used in place of methyl methacrylate in the mixture (c) of Synthetic Example C-1.

Synthetic Example C-4 A compatibilizing agent obtained by adding 50 parts of ESI during the hydrolysis-condensation reaction of Synthetic Example C-3.

Synthesis of Component (E) Synthesis Example E-1 18 parts of xylene and ESI were placed in a reaction vessel equipped with a stirrer, a thermometer, a reflux condenser, a nitrogen gas inlet tube and a dropping funnel.
40 parts of 40 parts were charged respectively, and while introducing nitrogen gas, 1
After the temperature was raised to 10 ° C., the mixture (d) having the following composition was added dropwise at a constant rate over 5 hours using a dropping funnel. Mixture (d) methyl methacrylate 25 parts n-butyl methacrylate 50 parts butyl acrylate 10 parts γ-methacryloxypropyltrimethoxysilane 10 parts n-methylolacrylamide 5 parts xylene 18 parts 2,2-azobisisobutyronitrile 1 Department.

After the addition of the mixture (d) was completed, 0.5 part of 2,2-azobisisopropionitrile was dissolved in 18 parts of xylene and added dropwise at a constant rate over 1 hour. 110 after the dropping
After aging for 2 hours at ℃, it was cooled and xylene was added to the resin solution to adjust the solid content to 50%. The number average molecular weight of the obtained resin was 15,000.

Example 1 100 parts of the resin obtained in Synthetic Example A-1 was used for Synthetic Example C.
-20 parts of the resin obtained in -1, and further M as the component (B)
50 parts of SI51 (tetraalkoxysilane partial condensate, manufactured by Colcoat Co., Ltd.) was blended.

Using this resin solution, titanium oxide (CR-90 manufactured by Ishihara Sangyo Co., Ltd.) was dispersed so that PWC (weight% of pigment based on the total solid content) 40% and coating solid content concentration 60% were dispersed. Adjusted the enamel. Dispersion was performed for 2 hours with a paint conditioner using glass beads.

To this white enamel, 0.25 parts of di (2-ethylhexyl) phosphoric acid and dimethyllaurylamine as a curing agent (C) were added to 100 parts of the resin, respectively, and diluted with thinner to a solid content of 45%. did.

This paint was applied to an aluminum plate (A5052P) by air spraying so that the dry film thickness was about 30 μm.

Thereafter, the coated plate was cured under the curing conditions (curing conditions) shown in [Table 1], and the stain resistance (outdoor exposure test), gloss, hardness and the like were measured. The results are shown in [Table 3].

Examples 2 to 7 and Comparative Examples 1 to 5 Compositions consisting of the components (A) to (E) shown in the following [Table 1] and [Table 2] were white enamel under the same conditions as in Example 1. Was adjusted.

Then, the curing agent (D) shown in [Table 1] and [Table 2] was added, and diluted with thinner so that the solid content concentration became 45%.

These paints were air-sprayed on an aluminum plate (A5052P) in the same manner as in Example 1.

Thereafter, the coated plate was cured under the curing conditions (curing conditions) shown in [Table 1] and [Table 2], and the same test as in Example 1 was conducted. The results are also shown in [Table 3].

[0076]

[Table 1]

[0077]

[Table 2]

[0078]

[Table 3]

[0079]

EFFECTS OF THE INVENTION According to the present invention, a curable composition for top coating composition having excellent compatibility with a silicon compound can be obtained without impairing the excellent function of the vinyl resin containing an alkoxy (hydrolyzable) silyl group.

Further, the coating film formed from the composition of the present invention has elasticity and excellent stain resistance.

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Claims (5)

(57) [Claims] 1. A general formula (A) (In the formula, R ¹ is an alkyl group having 1 to 10 carbon atoms or a phenyl group, 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, a represents 0, 1 or 2), and contains 100 parts by weight of an acrylic copolymer containing an alkoxysilane group having a silicon atom bonded to a carbon atom and not containing a siloxane bond. (B) General formula (Wherein R ³ is an alkyl group having 1 to 10 carbon atoms, R ⁴ is an alkyl group having 1 to 10 carbon atoms, a phenyl group or an alkoxy group, and a is 0, 1 or 2) Alternatively, 2 to 70 parts by weight of the partially hydrolyzed condensate thereof (C) The above (B) with respect to 100 parts by weight of the above (A) component.
A curable composition for topcoat paints, which comprises from 2 to 70 parts by weight of an alkoxysilyl group-containing acrylic copolymer obtained by condensing the components from 5 to 90 parts by weight (D) and from 0.1 to 20 parts by weight of a curing agent. 2. The composition according to claim 1, wherein the component (A) is a polymer containing 5 to 90% by weight of a structural unit derived from a monomer having a polymerizable double bond and an alkoxysilyl group in the molecule. object. 3. The component (A) and the component (B), wherein the component (C) contains n-butyl methacrylate as a copolymerization component.
The composition according to claim 1 or 2, which is a copolymer obtained by condensing the components. 4. An alkoxysilyl group-containing copolymer (E) obtained by polymerizing 100 parts by weight of all copolymerization components of the component (A) in the presence of 2 to 70 parts by weight of the component (B). The composition according to any one of claims 1 to 3, which is formulated in place of the component (A). 5. The composition according to any one of claims 1 to 4, wherein the copolymerization component of the component (A) contains n-butyl methacrylate.