JP3069979B2 - Curable composition - 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, and more specifically, for example, to a building exterior, an automobile, an industrial machine,
The present invention relates to a curable composition suitable for use as a top coat for steel furniture, home appliances, and plastics members.

[0002]

2. Description of the Related Art
As a thermosetting paint, for example, a paint composed of alkyd melamine, acrylic melamine and epoxy melamine is known. Since these paints use volatile melamine as a crosslinking agent for the polyol, odor caused by by-products generated has been regarded as a problem. In order to solve this problem, polyols and hydrolyzable silyls are crosslinked in a completely different form from conventional crosslinks with polyols and melamine to give cured coatings with excellent weather resistance, chemical resistance, solvent resistance, etc. A paint comprising a mixture of a group-containing polymer has been proposed (see Japanese Patent Application Laid-Open No. 1-14952). However, this mixture has a problem that the balance of physical properties of hardness and impact resistance and the interlayer adhesion when baked by two coats and two bake are generally poor. The present invention has been made in view of such circumstances, and a purpose thereof is to improve the impact resistance without impairing the hardness and the physical property balance of the impact resistance, that is, to improve the impact resistance without impairing the hardness, or to perform two-coat two-bake. An object of the present invention is to provide a curable composition capable of providing a cured coating film exhibiting excellent interlayer adhesion even when baked.

[0003]

According to the present invention, there is provided a curable composition comprising a hydroxyl group-containing acrylic resin (A) and an alkoxysilyl group-containing acrylic resin represented by the following general formula (1). A copolymer (B), a curing catalyst (C), an alcohol (D) having a boiling point of 120 ° C. or higher ,
Dehydrating agent (E) and boiling point of methanol, ethanol, etc. 12
And alkyl alcohol (F) having a temperature of less than 0 ° C.

[0004]

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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 1 to 10 carbon atoms.
A is 0, 1 or 2; a monovalent hydrocarbon group selected from the group consisting of an alkyl group having 1 to 10 carbon atoms and an aryl group having 1 to 10 carbon atoms and an aralkyl group having 1 to 10 carbon atoms.

[0006] The acrylic resin (A) having a hydroxyl group in the present invention is for making the cured product immediately after baking exhibit various physical properties such as hardness and solvent resistance. Since the main chain is substantially composed of an acrylic copolymer, the cured product is excellent in weather resistance, chemical resistance, water resistance and the like. The acrylic resin (A) having a hydroxyl group can be obtained, for example, by copolymerizing a hydroxyl-containing vinyl polymerizable compound with acrylic acid, methacrylic acid, or a derivative thereof. Examples of the hydroxyl-containing vinyl polymerizable compound in this case include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxyethyl vinyl ether, N-methylol (meth) acrylamide, and Toa Gosei Chemical Industry. Alonix 5700, 4-hydroxystyrene, manufactured by Nippon Shokubai Chemical Co., Ltd., HE-10, HE-20, HP-10
And HP-20 (all of which are acrylic acid ester oligomers having a hydroxyl group at the terminal), Blemmer-PP series (polypropylene glycol methacrylate), Blemmer-PE series (polyethylene glycol monomethacrylate), Blemmer-PEP series manufactured by NOF Corporation (Polyethylene glycol polypropylene glycol methacrylate), Blemmer-AP-400 (polypropylene glycol monoacrylate), Blemmer-
AE-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, ε-
A caprolactone-modified hydroxyalkylvinyl-based monomer is preferable because it can impart more excellent impact resistance and flexibility to the coating film. Representative examples of such ε-caprolactone-modified hydroxyalkylvinyl monomers include vinyl monomers represented by the following general formula (3).

[0007]

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In the chemical formula 3, R is H or CH ₃ , and n is an integer of 1 or more. Commercially available products of the vinyl monomer represented by Chemical Formula 3 include Placel manufactured by Daicel Chemical Industries, Ltd.
FA-1 (R = H, n = 1), the same Placel FA
-4 (R = H, n = 4), Placel FM-1
(R = CH ₃ , n = 1) and the same Placel FM-4
(R = CH ₃ , n = 4), TONE M- manufactured by UCC
100 (R = H, n = 2) and TONE M-20
1 (R = CH ₃ , n = 1) and the like. These hydroxyl group-containing vinyl polymerizable compounds may be used alone or in combination of two or more as needed. The derivative of acrylic acid or methacrylic acid copolymerizable with the hydroxyl group-containing vinyl polymerizable compound is not particularly limited, and specific examples thereof include methyl acrylate and methyl methacrylate (hereinafter, acrylate and methacrylate are referred to as “(meth) acrylate”. Generic name), ethyl (meth) acrylate, butyl (meth) acrylate, 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, Tylaminoethyl (meth) acrylate, (meth) acrylamide, α-ethyl (meth) acrylamide, N-butoxymethyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-methylacrylamide, acryloylmorpholine, N- Methylol (meth) acrylamide, AS-6, AN-6, AA-, which are macromonomers manufactured by Toa Gosei Chemical Industry Co., Ltd.
6, AB-6, AK-5, condensation products of hydroxyalkyl esters of α, β-ethylenically unsaturated carboxylic acids, such as hydroxyalkyl esters of (meth) acrylic acid, with phosphoric acid or phosphate esters And a (meth) acrylate containing a urethane bond or a siloxane bond. Acrylic resin (A) having a hydroxyl group is 50% by weight (hereinafter, referred to as "
As long as it does not exceed "%", the main chain may include a portion formed by a urethane bond or a siloxane bond, and may include a portion derived from a monomer other than the (meth) acrylic acid derivative. Is also good. The above-mentioned monomers are not limited, and specific examples thereof include aromatic hydrocarbon-based vinyl compounds such as styrene, α-methylstyrene, chlorostyrene, styrenesulfonic acid, and vinyltoluene; maleic acid, fumaric acid, itaconic acid, and the like. An unsaturated carboxylic acid,
Their salts (alkali metal salts, ammonium salts, amine salts, etc.), their acid anhydrides (maleic anhydride, etc.),
Or an unsaturated carboxylic acid ester such as a diester or a half ester thereof with a linear or branched alcohol having 1 to 20 carbon atoms; a vinyl ester or an allyl compound such as vinyl acetate, vinyl propionate or diallyl phthalate; Amino-containing vinyl compounds such as aminoethyl vinyl ether; itaconic acid diamide;
Amide group-containing vinyl compounds such as crotonamide, maleic acid diamide, fumaric acid diamide, N-vinylpyrrolidone; methyl vinyl ether, cyclohexyl vinyl ether, vinyl chloride, vinylidene chloride, chloroprene,
Other vinyl compounds such as propylene, butadiene, isoprene, fluoroolefin maleimide, N-vinylimidazole, and vinyl sulfonic acid are exemplified. As a method for synthesizing the acrylic resin (A) having a hydroxyl group, a solution polymerization method using an azo-based radical initiator such as azobisisobutyronitrile is preferable because the synthesis is easy. In the solution polymerization method, if necessary, the molecular weight may be adjusted using a chain transfer agent such as n-dodecyl mercaptan, t-dodecyl mercaptan, or n-butyl mercaptan. The solvent used for the solution polymerization is not particularly limited as long as it is a solvent that is non-reactive with the raw material monomers and the like. Also, 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. Although the molecular weight of the acrylic resin (A) having a hydroxyl group is not particularly limited, the properties of a cured coating film such as durability formed from the curable composition according to the present invention (hereinafter, referred to as “coating film physical properties”). The number average molecular weight is preferably from 1,500 to 40,000,
2,000 to 25,000 are more preferred. The acrylic resin (A) having a hydroxyl group must have a sufficient number of crosslinkable hydroxyl groups, and has a hydroxyl value of 10 to 300 mg KOH in terms of strength and durability.
/ G, preferably from 20 to 150 mg KOH /
g is more preferred. The acrylic resin (A) having a hydroxyl group may be used alone or in combination of two or more as needed.

The alkoxysilyl group-containing acrylic copolymer (B) in the present invention has at least one, and preferably two or more, alkoxysilyl groups represented by the following general formula (4). If the average number of alkoxysilyl groups in one molecule is less than 1, the solvent resistance of the resulting coating film will be poor.

[0010]

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However, in the chemical formula 4, R ¹ has 1 to 10 carbon atoms;
Preferably, an alkyl group having 1 to 4 carbon atoms, R ² is a hydrogen atom, or an alkyl group having 1 to 10 carbon atoms, preferably an aryl group having 1 to 10 carbon atoms, an aralkyl group having 1 to 10 carbon atoms. A monovalent hydrocarbon group selected from the group consisting of
a is 0, 1 or 2. The alkoxysilyl group represented by Chemical formula 4 may be contained at the terminal of the main chain of the alkoxysilyl group-containing acrylic copolymer (B), may be contained in the side chain, or may be contained at the terminal of the main chain. And in both the side chains. When the carbon number of R ¹ exceeds 10, the hydrolysis reactivity of the alkoxysilyl group decreases, and even when R ¹ is a group other than an alkyl group, for example, a phenyl group or a benzyl group, the hydrolysis reactivity decreases. . Specific examples of R ¹ include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and an isobutyl group. R
Specific examples of the alkyl group in ² include the same alkyl groups as those described in the description of R ¹ , specific examples of the aryl group include a phenyl group, and specific examples of the aralkyl group include And a benzyl group. Specific examples of the alkoxysilyl group represented by Chemical Formula 4 include a group contained in an alkoxysilyl group-containing monomer described below. Since the main chain of the alkoxysilyl group-containing acrylic copolymer (B) is substantially composed of an acrylic copolymer, the cured product obtained has weather resistance, chemical resistance,
Excellent in water resistance and the like. Further, since the alkoxysilyl group is directly bonded to the carbon atom, the cured product has excellent water resistance, alkali resistance, acid resistance and the like. The number average molecular weight of the alkoxysilyl group-containing acrylic copolymer (B) is preferably in the range of 1,000 to 30,000, and more preferably 3,000, from the viewpoint of the properties of the coating film obtained from the curable composition according to the present invention. A range of ２５25,000 is more preferred. Acrylic copolymer containing alkoxysilyl group (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 acrylic acid or methacrylic acid derivative is not particularly limited, and specific examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, and stearyl (meth). Acrylate, benzyl (meth) acrylate, cyclohexyl (meth) acrylate, trifluoroethyl (meth) acrylate, pentafluoropropyl (meth) acrylate, perfluorocyclohexyl (meth) acrylate, (meth) acrylonitrile, glycidyl (meth) acrylate, dimethyl Aminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, (meth) acrylamide, α-ethyl (meth) acrylamide, N-butoxymethyl (meth) acryl Mido, N, N-dimethylacrylamide, N-methylacrylamide, acryloylmorpholine, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, N-methylol (meth) acrylamide, manufactured by Toa Gosei Chemical Industry Co., Ltd. Alonix M-57
A, a macromonomer manufactured by Toa Gosei Chemical Industry Co., Ltd.
S-6, AN-6, AA-6, AB-6, AK-5, Placel FA-1, Pl manufactured by Daicel Chemical Industries, Ltd.
accel FA-4, Placel FM-1, P
Laccel FM-4, a phosphoric acid ester which is a condensation product of a hydroxyalkyl ester of an α, β-ethylenically unsaturated carboxylic acid such as a hydroxyalkyl ester of (meth) acrylic acid and a phosphoric acid or a phosphoric acid ester. Examples include a 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 compounds represented by the following formulas (5) to (16). A (meth) acrylate having a group via a urethane bond or a siloxane bond may be used.

[0012]

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[0013]

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[0014]

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[0015]

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[0016]

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[0017]

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[0018]

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[0019]

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[0020]

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[0021]

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[0022]

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[0023]

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The proportion of the portion formed by the alkoxysilyl group-containing monomer in the alkoxysilyl group-containing acrylic copolymer (B) is preferably in the range of 5 to 90% from the viewpoint of the curability of the composition and the physical properties of the coating film. And the range of 11 to 70% is more preferable. The alkoxysilyl group-containing acrylic copolymer (B) may contain a portion formed by a urethane bond or a siloxane bond in the main chain within a range not exceeding 50%, and may be other than a (meth) acrylic acid derivative. May be included. The monomer other than the above (meth) acrylic acid derivative is not particularly limited, and specific examples thereof include aromatic hydrocarbons such as styrene, α-methylstyrene, chlorostyrene, styrenesulfonic acid, 4-hydroxystyrene, and vinyltoluene. Vinyl compounds; unsaturated carboxylic acids such as maleic acid, fumaric acid, itaconic acid, salts thereof (alkali metal salts, ammonium salts, amine salts, etc.), their acid anhydrides (maleic anhydride, etc.), or Unsaturated carboxylic acid esters such as diesters or half esters with linear or branched alcohols having 1 to 20 carbon atoms; vinyl esters or allyl compounds such as vinyl acetate, vinyl propionate and diallyl phthalate; vinyl pyridine, aminoethyl vinyl ether and the like Amino group-containing vinyl compounds; itaconic acid Amides, crotonamide, maleic acid diamide,
Amide group-containing vinyl compounds such as fumaric diamide and N-vinylpyrrolidone; 2-hydroxyethyl vinyl ether, methyl vinyl ether, cyclohexyl vinyl ether, vinyl chloride, vinylidene chloride, chloroprene,
Other vinyl compounds such as propylene, butadiene, isoprene, fluoroolefin maleimide, N-vinylimidazole, and vinyl sulfonic acid are exemplified. The alkoxysilyl group-containing acrylic copolymer (B) is described in, for example, JP-A-54-36395 and JP-A-57-36109.
And the methods disclosed in JP-A-58-157810, etc., but from the viewpoint of easiness of synthesis and the like, the solution weight is reduced using an azo-based radical initiator such as azobisisobutyronitrile. Most preferably, it is produced by a legal method. During the solution polymerization, 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 or a compound represented by the following formula (17). Further, a chain transfer agent having an alkoxysilyl group in the molecule, for example, γ-
By using mercaptopropyltrimethoxysilane and continuously replenishing the amount consumed during the progress of the reaction,
It is preferable because an alkoxysilyl group can be introduced into the terminal of the silyl group-containing acrylic copolymer together with the adjustment of the molecular weight.

[0025]

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Examples of the polymerization solvent in the case of the above solution polymerization method include hydrocarbons (toluene, xylene, n-hexane, cyclohexane, etc.), acetates (ethyl acetate, butyl acetate, etc.), and ethers (ethylene glycol monoethyl acetate). Ether, ethylene glycol mono-n-
Any solvent that is non-reactive with the raw material monomer, such as butyl ether, ethylene glycol monoethyl ether acetate), ketones (methyl ethyl ketone, ethyl acetoacetate, acetylacetone, methyl isobutyl ketone, acetone, etc.) can be used without particular limitation. .
The alkoxysilyl group-containing acrylic copolymer (B) in the present invention may be used singly or may be used depending on the application.
More than one species may be used in combination.

In the present invention, the mixing ratio of the hydroxyl group-containing acrylic resin (A) and the alkoxysilyl group-containing acrylic copolymer (B) is not particularly limited.
(B) The component ratio is preferably in the range of 9/1 to 1/9 by weight, more preferably in the range of 8/2 to 2/8. (A) /
(B) When the component ratio exceeds 9/1, the water resistance of the coating film obtained from the composition of the present invention tends to decrease, and when it is less than 1/9, the mixing effect of the acrylic resin (A) having a hydroxyl group. Tend not to be sufficiently obtained.

Specific examples of the curing catalyst (C) in the present invention include dibutyltin laurate, dibutyltin dimaleate, dioctyltin dilaurate, dioctyltin dimaleate, a polymer of dioctyltin maleate, and organotins such as tin octylate. Compounds: Phosphoric acid or phosphate such as phosphoric acid, monomethyl phosphate, monoethyl phosphate, monobutyl phosphate, monooctyl phosphate, monodecyl phosphate, dimethyl phosphate, diethyl phosphate, dibutyl phosphate, dioctyl phosphate, didecyl phosphate; propylene oxide , Butylene oxide, cyclohexene oxide, glycidyl methacrylate,
Glycidol, acrylic glycidyl ether, γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropylmethyldimethoxysilane, a compound represented by the following formula (18), Yuka Shell Epoxy Reaction product of an epoxy compound such as Cardura E, Epicort 828, Epicort 1001, and the like with phosphoric acid and / or monoacidic phosphate; organic titanate compound; tris (ethylacetoacetate) aluminum, tris (acetylacetonate) ) Organoaluminum compounds such as aluminum;
Organic zirconium compounds such as tetrabutyl zirconate, tetrakis (acetylacetonato) zirconium, tetraisobutylzirconate, butoxytris (acetylacetonato) zirconium; maleic acid, adipic acid, azelaic acid, sebacic acid, itaconic acid, citric acid, Acidic compounds such as succinic acid, phthalic acid, trimellitic acid, pyromellitic acid, their anhydrides and paratoluenesulfonic acid; hexylamine, di-2-ethylhexylamine, N, N-dimethyldodecylamine, dodecylamine and the like Amines; mixtures or reactants of these amines with acidic phosphate esters; and alkaline compounds such as sodium hydroxide and potassium hydroxide.

[0029]

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Among the above exemplified curing catalysts (C), organotin compounds, acid phosphates, mixtures or reactants of acid phosphates and amines, saturated or unsaturated polycarboxylic acids or anhydrides thereof , Reactive silicon compounds, organic titanate compounds, organic aluminum compounds,
Organic zirconium compounds or mixtures of two or more thereof are preferred because of their high activity. The curing catalyst (C) in the present invention may be used alone or in combination of two or more as needed. Although the amount of the curing catalyst (C) is not particularly limited, the resin solid content of the acrylic resin (A) having a hydroxyl group and the acrylic copolymer (B) having an alkoxysilyl group (B) is 100 parts by weight (hereinafter abbreviated as "part"). ) Is usually preferably in the range of 0.1 to 20 parts,
A range of from 10 to 10 parts is more preferable. If the amount of the curing catalyst (C) is less than 0.1 part, the curability tends to decrease, and if the amount exceeds 20 parts, the appearance of the coating film tends to deteriorate, which is not preferable.

Specific examples of the alcohol (D) having a boiling point of 120 ° C. or higher in the present invention include n-amyl alcohol, isoamyl alcohol, 3-methoxybutyl alcohol, n-hexyl alcohol, 2-methylpentanol, and secondary hexyl. Alcohol, 2-ethylbutyl alcohol, secondary heptyl alcohol, heptanol, n-octyl alcohol, 2-ethylhexyl alcohol, secondary octyl alcohol, nonyl alcohol, 2,6-dimethyl-4-heptanol, n-decanol, n-dodecanol , Secondary undecyl alcohol, trimethyl nonyl alcohol, secondary tetradecyl alcohol, phenol, cyclohexanol, methyl cyclohexanol,
Examples include 3,3,5-trimethylcyclohexanol, benzyl alcohol, and diacetone alcohol. If the boiling point of the alcohol (D) is lower than 120 ° C., the alcohol volatilizes during spray coating or during setting before heat curing, and a sufficient effect cannot be obtained. Alcohol (D) has a high boiling point and therefore remains in the coating film until the end of curing. It is thought that this changes the surface properties of the final coating film and improves the balance between hardness and impact resistance and the adhesion between layers in two coats and two bake. The mixing amount of the alcohol (D) is 3 to 100 with respect to 100 parts of the total resin solid content of the acrylic resin (A) having a hydroxyl group and the alkoxysilyl group-containing acrylic copolymer (B).
Is preferably in the range of 5 to 70 parts. If the blending amount of the alcohol (D) is less than 3 parts, the impact resistance and interlayer adhesion become insufficient, and if it exceeds 100 parts, the viscosity is reduced and the workability is deteriorated, which is not preferable. The alcohol (D) may be blended with one or both of the acrylic resin (A) and the alkoxysilyl group-containing acrylic copolymer (B) at any time before, during, or after the polymerization, Further, it may be blended after blending the acrylic resin (A) having a hydroxyl group and the acrylic copolymer (B) having an alkoxysilyl group,
In particular, when the alcohol (D) is used as a polymerization solvent for the acrylic resin (A) and the alkoxysilyl group-containing acrylic copolymer (B), the compatibility between the alcohol and the resin becomes sufficient and the effect is stabilized. Dehydrating agent (E) and alkyl alcohol
(F) shows no problem for long-term repeated use.
This is to ensure good storage stability. Dehydrating agent
Specific examples of (E) include, for example, methyl orthoformate,
Ethyl orthoformate, methyl orthoacetate, ethyl orthoacetate
, Methyltrimethoxysilane, γ-methacryloxyp
Ropirtrimethoxysilane, vinyltrimethoxysila
Of methyl, silicate, ethyl silicate, etc.
Ester compounds. These dehydrating agents (E)
And an alkyl alcohol (F) having a boiling point of less than 120 ° C
Is the alkoxysilyl group-containing acrylic copolymer (B)
May be added before polymerization, may be added after polymerization, during polymerization
May be added. Dehydrating agent (E) and alkyl alcohol
There is no particular limitation on the amount of (F), but it has a hydroxyl group.
Acrylic resin (A) and alkoxysilyl group-containing resin
100 parts by weight of the total resin solid content of the cryl copolymer (B)
Is preferably in the range of 0.5 to 20 parts, and more preferably in the range of 2 to 10 parts.
Enclosures are more preferred. Thus, the dehydrating agent (E) and the alkyl
Storage stability when used in combination with alcohol (F)
Properties can be significantly improved.

An aminosilane-based compound may be added to the curable composition of the present invention in order to improve adhesion to a metal substrate such as aluminum and stainless steel. The aminosilane-based compound referred to herein means a compound having a silicon-containing group bonded to an amino group and at least one hydrolyzable group in one molecule. Examples of such an aminosilane-based compound include a silane coupling agent containing an amino group such as compounds represented by the following formulas 19, 20, and 21;
These amino-containing silane coupling agents and
A reaction product with an epoxy group-containing silane coupling agent such as a compound represented by 2, 23; an amino group-containing silane coupling agent, ethylene oxide, butylene oxide, epichlorohydrin, epoxidized soybean oil,
In addition, Epicoat 828 and Epicoat 10 manufactured by Shell
01, Epolite 400 manufactured by Kyoeisha Yushi Kagaku Kogyo Co., Ltd.
0, Epolite 40E, Chisso ERL-420
6, a reaction product with a compound having an epoxy group such as ERL-4221 and ERL-4299.

[0033]

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[0034]

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[0035]

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[0036]

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[0037]

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The amount of the aminosilane-based compound added is the total amount of the resin solids of the acrylic resin (A) having a hydroxyl group and the acrylic copolymer (B) having an alkoxysilyl group (B).
The range of 0.2 to 10 parts is preferable for 00 parts,
A range of 7 parts is more preferred. If the amount of the aminosilane-based compound is less than 0.2 part, the effect of improving the adhesion to the metal substrate is not exhibited, and if it exceeds 10 parts, the weather resistance is reduced, and both are not preferred . The curable composition according to the present invention, depending on the application, diluents, pigments such as extenders,
Additives such as ultraviolet absorbers, light stabilizers, anti-settling agents, leveling agents; fibrous materials such as nitrocellulose and cellulose acetate butyrate; epoxy resins, melamine resins, vinyl chloride resins, chlorinated polypropylene, chlorinated rubber, polyvinyl butyral And the like; a filler and the like may be added. After the curable composition according to the present invention is applied to an object to be coated by various coating methods, for example, dipping, spraying, or brushing, the coating is usually applied at 50 ° C. or higher, preferably 70 to 350 ° C.
By curing at ° C., adhesion to the surface of the object to be coated,
A cured coating film having excellent durability and the like can be formed.

[0039]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples. However, the present invention is not limited to the following examples, and the present invention may be practiced by appropriately changing the gist of the invention. Is possible.

Synthesis Example 1 Synthesis of Acrylic Resin (A) Having a Hydroxy Group A reactor equipped with a stirrer, thermometer, reflux condenser, nitrogen gas inlet tube and dropping funnel was charged with 31.3 parts of butyl acetate.
After charging 9.5 parts of xylene and raising the temperature to 110 ° C. while introducing nitrogen gas through a nitrogen gas introducing pipe, a mixture having the following composition was dropped at a constant rate from the dropping funnel over 5 hours. Xylene 18.0 parts Styrene 37.0 parts n-butyl acrylate 24.0 parts Placel FM-4 39.0 parts 2,2'-azobisisobutyronitrile 1.8 parts 0.2 parts of 2-azobisisobutyronitrile and 3.8 parts of toluene were added dropwise over 1 hour. Next, the mixture was reacted at 110 ° C. for 2 hours and cooled, and xylene was added to the resin solution to adjust the solid content concentration to 60% to obtain an acrylic resin (A) having a hydroxyl group. This acrylic resin had a hydroxyl value (mg KOH / g solid) of 37 and a number average molecular weight of 10,000. The above-mentioned Placel FM-4 is a reaction product of 2-hydroxyethyl methacrylate and ε-caprolactone, manufactured by Daicel Chemical Industries, Ltd.

[Synthesis Example 2] Synthesis of Acrylic Copolymer Containing Alkoxysilyl Group (B) Into the same reactor as in Synthesis Example 1, 45.9 parts of xylene was charged and heated to 110 ° C while introducing nitrogen gas. After the temperature rises,
A mixture having the following composition was dropped at a constant speed from the dropping funnel over 5 hours. Styrene 12.8 parts Methyl methacrylate 45.7 parts Methacrylamide 1.5 parts γ-methacryloxypropyltrimethoxysilane 40.0 parts Xylene 13.5 parts 2,2′-azobisisobutyronitrile 1.0 part After the addition of the mixture was completed, 0.5 part of 2,2-azobisisobutyronitrile and 5 parts of toluene were added dropwise at a constant speed over 1 hour. Then, after aging at 110 ° C for 2 hours, it was cooled,
Xylene was added to adjust the solid concentration to 60% to obtain an alkoxysilyl group-containing acrylic copolymer (B). The number average molecular weight of this copolymer was 15,000.

(Examples 1 to 4) In a 400 ml glass bottle, 102.8 g of the solution of the acrylic resin (A) having a hydroxyl group obtained in Synthesis Example 1, titanium oxide (product code "CR90" manufactured by Ishihara Sangyo Co., Ltd.) 72 g, methanol 11
g, 11 g of methyl orthoacetate, 26 g of xylene, and 70 ml of glass beads.
Time dispersion was performed. Next, 77.2 g of the solution of the alkoxysilyl group-containing acrylic copolymer (B) obtained in Synthesis Example 2 was added to the mixture, and the mixture was stirred and dispersed for 30 minutes to obtain a white enamel having a solid content of 60%. To 30 g of the white enamel thus obtained, 0.05 g of dioctyltin dimaleate was added.
g, 0.22 g of an equivalent reaction product of Epicoat 828 and γ-aminopropyltriethoxysilane, and 4.5 g of each alcohol having a boiling point of 120 ° C. or higher shown in Tables 1 and 2.
And an aluminum plate (A1050 plate thickness 0.8
mm), and baked at 140 ° C. for 20 minutes. The interlayer adhesion at the time of 2 coats and 2 baking in Tables 1 and 2 is as follows. On the thus baked coating film, white enamel is further applied in the same composition, baked at 140 ° C. for 20 minutes, and after 2 hours of boiling water This is an evaluation of the adhesion between the two layers.

[0043]

[Table 1]

[0044]

[Table 2]

The intercoat adhesion between the two coats and two bake in Tables 1 and 2 is obtained by cutting a test piece on a 1 mm grid, peeling it off with a cellophane tape, and evaluating the degree of peeling on a 10-point scale.

Comparative Example 1 A coating material was prepared in the same manner as in Examples 1 to 4 except that an alcohol having a boiling point of 120 ° C. or higher was not blended, and a similar evaluation test was performed. Table 2 shows the results.

[0047]

The curable composition according to the present invention improves the balance between the physical properties of hardness and impact resistance, that is, improves the impact resistance without impairing the hardness, and improves the interlayer adhesion in two coats and two bake. For example, the present invention has excellent unique effects.

──────────────────────────────────────────────────の Continued on the front page (58) Fields surveyed (Int. Cl. ⁷ , DB name) C09D 133/14 C08G 81/02 CA (STN) CAOLD (STN) REGISTRY (STN) WPIDS (STN)

Claims (4)

(57) [Claims] An acrylic resin having a hydroxyl group (A), an alkoxysilyl group-containing acrylic copolymer represented by the following general formula (B), a curing catalyst (C), and a boiling point of 120 °
C or more alcohol (D) , dehydrating agent (E), and methano
Alkyl, ethanol, etc. having a boiling point of less than 120 ° C.
Curable composition characterized by consisting of a alcohol (F). Embedded image However, in Chemical formula 1, R ¹ is an alkyl group having 1 to 10 carbon atoms,
R ² is a hydrogen atom, an alkyl group having 1 to 10 carbon atoms, an aryl group having 1 to 10 carbon atoms, and 1 to 10 carbon atoms.
A is 0, 1 or 2; and a is a monovalent hydrocarbon group selected from the group consisting of 2. The acrylic resin having a hydroxyl group (A)
The curable composition according to claim 1, wherein the hydroxyl value is 10 to 300 mgKOH / g, and the number average molecular weight is 1,500 to 40,000. 3. An alkoxysilyl group-containing acrylic copolymer (B) containing from 5 to 90% by weight of an alkoxysilyl group-containing monomer unit having a polymerizable double bond and an alkoxysilyl group in the molecule. The curable composition according to claim 1, which is: 4. The curing catalyst (C) comprises an organotin compound,
Acidic phosphates, mixtures or reactants of acidic phosphates and amines, saturated or unsaturated polycarboxylic acids, anhydrides of saturated or unsaturated polycarboxylic acids, reactive silicon compounds, organic titanate compounds, organic The curable composition according to claim 1, which is an aluminum compound, an organic zirconium compound, or a mixture of two or more thereof.