JPH10147743A - Finish coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an automotive finish coating composition excellent in staining resistance. SOLUTION: This composition comprises an acid epoxy curing coating composition and a silicone compound being a condensate of a partial hydrolyzate of a mixture comprising 100 pts.wt. alkoxysilane compound containing at least one organic functional group selected from among mercapto, epoxy, (meth) acryloyl, vinyl, haloalkyl and amino and 20-2,000 pts.wt. tetraalkoxysilane compound.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel top coating composition, and more particularly to a top coating composition capable of forming a coating film having excellent stain resistance, acid resistance, weather resistance and the like.

[0002]

2. Description of the Related Art Conventionally, air pollution has progressed, and damage caused by acid rain such as forest withering has become a serious social problem. However, it has been applied to articles used outdoors such as automobile outer panels. Also in the coating film, there are problems that the coating film is etched, and that the coating film is whitened, stained, and the like.

[0003] A melamine-curable coating is generally used as a coating for automobile outer panels, and a coating film formed from the melamine-curable coating is subjected to a hydrolysis reaction by an acid to form a melamine resin crosslinked portion. It becomes water soluble and the coating deteriorates. When contaminants such as smoke adhere to such a poorly acid-resistant coating film, there is a problem that dirt is hardly removed and the coating film appearance is extremely deteriorated.

[0004] As a non-melamine-curable coating material which forms a coating film having excellent acid resistance, an acid epoxy-curable coating material has been developed. There is a problem in that once adhered, dirt is difficult to remove.

[0005]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to solve the above-mentioned problems, and as a result, by adding a specific silicone compound to an acid epoxy-curable coating composition, an automobile has been developed. The present inventors have found that a coating film having excellent stain resistance can be provided without deteriorating the appearance and performance of the outer plate, and have completed the present invention.

The present invention provides: (1) mercapto group, epoxy group, (meth) acryloyl group, vinyl group,
Alkoxysilane compound (a) containing at least one organic functional group selected from haloalkyl groups and amino groups
Topcoat paint characterized by blending a silicone compound (A) which is a partially hydrolyzed condensate of a silane mixture of 100 parts by weight and (2) a tetraalkoxysilane compound (b) of 20 to 2,000 parts by weight. 1. a composition (hereinafter abbreviated as "present invention I"); The acid epoxy-curable coating composition has the following general formula: R1 R2 SiZ2 (wherein R1 is an epoxy group, a mercapto group, (meth)
Represents an organic functional group such as an acryloyl group, a vinyl group, a haloalkyl group or an amino group, R2 represents an alkyl group having 1 to 3 carbon atoms, and Z is bonded to another silicon atom by a hydrolyzable group or a siloxane bond. A D unit as a silicon structural unit represented by the following formula: and / or a T1 unit as a silicon structural unit represented by the general formula R1SiZ3 (wherein R1 and Z have the same meanings as described above). ~ 80
(2) T2 units as silicon structural units represented by the general formula R2SiZ3 (wherein R2 and Z have the same meaning as described above) are 0.1 to 0.1%.
(3) containing 10 to 94.9 mol% of a Q unit as a silicon structural unit represented by the general formula SiZ4 (wherein Z has the same meaning as described above), provided that T2 The total amount of units and Q units is 20
An overcoating composition (hereinafter, referred to as the "coating composition") comprising a silicone compound (B) having an organic functional group and a hydrolyzable group in one molecule having an average degree of polymerization of 3 to 100 mol% to 95 mol%. Abbreviated as "the present invention II"); R represented by the above general formula R1 R2 SiZ2
3. The top coating composition according to the above (1) or (2), wherein the organic functional group 1 is a mercapto group; The above-mentioned top coating composition, wherein the acid epoxy curing type coating composition is an acid epoxy silane curing type coating composition obtained by mixing an alkoxysilyl group-containing vinyl (co) polymer with the coating composition. About.

The acid-epoxy curable coating composition used in the present invention comprises an epoxy- and hydroxyl-containing acrylic copolymer as a base resin and a carboxyl-containing compound as a curing agent. Is preferred. Further, the acrylic copolymer may contain a functional group such as an alkoxysilyl group.

The epoxy- and hydroxyl-containing acrylic copolymers include, for example, epoxy-containing acrylic monomers such as glycidyl (meth) acrylate, hydroxyl-containing radically polymerizable unsaturated monomers, and other radical polymerizable if necessary. Copolymers obtained by subjecting unsaturated monomers to a radical copolymerization reaction are exemplified.

Examples of the hydroxyl group-containing radical polymerizable unsaturated monomer include 2-hydroxyethyl (meth) acrylate, 3-hydroxybutyl (meth) acrylate, polyethylene glycol mono (meth) acrylate, and caprolactone-modified hydroxyethyl. .

As other radically polymerizable unsaturated monomers, for example, methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, octyl ( Alkyl or cycloalkyl esters of acrylic acid such as meth) acrylate, stearyl (meth) acrylate, perfluorobutylethyl (meth) acrylate, perfluoroisononylethyl (meth) acrylate, and cyclohexyl (meth) acrylate; fragrance such as styrene Group compounds; γ
Hydrolyzable alkoxy such as-(meth) acryloyloxypropyltrimethoxysilane, γ- (meth) acryloyloxypropyltriethoxysilane, γ- (meth) acryloyloxypropylmethyldimethoxysilane, vinyltrimethoxysilane, vinylmethyldimethoxysilane Examples include silyl group-containing acrylic monomers. These unsaturated monomers can be used alone or in combination of two or more.

The acrylic copolymer containing epoxy groups and hydroxyl groups has an epoxy group content of 0.5 to 5.0 mmol / g, particularly 0.8 to 2.5 mmol / g, and a hydroxyl group content of 10 to 10 mmol / g. 200 mgKOH / g, especially 30-120 mgKOH / g
Is preferable. When a hydrolyzable alkoxysilyl group is contained in the copolymer, the functional group may be added in an amount of 0.1.
The range is preferably 1 to 5.0 mmol / g, particularly preferably 1.0 to 3.0 mmol / g.

When the epoxy group content of the epoxy group- and hydroxyl group-containing acrylic copolymer is less than 0.5 mmol / g, the curability of the resulting composition is reduced and the acid resistance and scratch resistance of the coating film are reduced. , The stain resistance tends to decrease,
Further, when the epoxy group content is more than 5.0 mmol / g, the stain resistance tends to decrease, and thus both are not preferred.

When the hydroxyl value of the acrylic copolymer containing an epoxy group and a hydroxyl group is less than 10 mgKOH / g, the curability of the resulting composition is lowered and the acid resistance of the coating film is reduced.
Both abrasion resistance and stain resistance tend to decrease, and when the hydroxyl value is more than 200 mgKOH / g, the water resistance of the coating film tends to decrease.

When a hydrolyzable alkoxysilyl group is contained in the acrylic copolymer containing an epoxy group and a hydroxyl group, the functional group is used in an amount of 0.1 to 5.0 mmol / g, particularly 1.0 to 3.0 mmol / g. 0 mmol / g is preferred.

When the content of the hydrolyzable alkoxysilyl group in the copolymer is less than 0.1 mmol / g, the curability of the resulting composition is reduced, and the acid resistance and scratch resistance of the coating film are reduced. When the content of the hydrolyzable alkoxysilyl group is more than 5.0 mmol / g, the cost increases, and neither is preferred.

The epoxy group- and hydroxyl group-containing copolymer preferably has a number average molecular weight of 2,000 to 10,000. If the number average molecular weight is less than 2,000, the weather resistance and durability of the stain resistance of the cured coating film tend to decrease, and if it exceeds 10,000, the stain resistance tends to decrease.

As the carboxyl group-containing compound, those having an acid value in the range of 50 to 500 mgKOH / g, particularly 80 to 300 mgKOH / g can be used. Acid value is 50mgKOH /
If it is smaller than g, the curability tends to decrease, and the acid resistance and stain resistance of the coating film tend to decrease.
If it exceeds 0 mgKOH / g, the water resistance, weather resistance,
This is not preferable because the durability of the stain resistance tends to decrease.

As the carboxyl group-containing compound, a conventionally known compound can be used without any particular limitation as long as the above conditions are satisfied. Specifically, for example, a maleic anhydride, an acid anhydride group-containing vinyl monomer such as itaconic anhydride half-esterified with a low molecular weight monoalcohol such as methanol or ethanol, or a half-esterified non-esterified monomer as required. Obtained by a radical polymerization reaction with a radically polymerizable unsaturated monomer (e.g., the same alkyl or cycloalkyl esters of acrylic acid, aromatic compounds, etc. as described above), provided that the monomer is not half-esterified. Ester polymer obtained by subjecting the obtained polymer to half esterification with a low molecular weight monoalcohol, a C2-10 polyol component such as ethylene glycol, propanediol, pentanediol, neopentyl glycol, and trimethylolpropane, and succinic acid Anhydride, maleic anhydride , Phthalic anhydride, tetrahydrophthalic acid anhydride, half ester and a carboxyl group-containing polyester resin with the acid anhydride component of C2-20 such as hexahydrophthalic acid anhydride.

The acid-epoxy-curable coating composition used in the present invention comprises an epoxy resin having an epoxy group and a hydroxyl group, a carboxyl group-containing compound containing an organic solvent (eg, an aromatic resin such as toluene or xylene, or a butyl acetate or the like). Ester-based, ketone-based such as methyl ethyl ketone and methyl isobutyl ketone, and alcohol-based such as propyl alcohol and butanol) dissolved or dispersed in an organic solvent-based coating composition. Resin solid part of paint (when spraying)
Is usually in the range of 30 to 80% by weight, especially 40 to 75% by weight.

The acid-epoxy curable coating composition used in the present invention may optionally contain a curing catalyst, a coloring pigment, an extender pigment, an ultraviolet absorber, an antioxidant, a surface conditioner, polymer fine particles, and the like. can do. Further, if necessary, a curing agent such as a melamine resin other than the carboxyl group-containing compound and a blocked polyisocyanate compound can be used in combination with the carboxyl group-containing compound.

The present invention I: The silicone compound (a) used in the present invention I is at least one organic functional group selected from a mercapto group, an epoxy group, a (meth) acryloyl group, a vinyl group, a haloalkyl group, and an amino group. Is obtained by partially co-hydrolyzing and condensing a mixture of an alkoxysilane compound (hereinafter referred to as “organic functional group-containing alkoxysilane compound”) and a tetraalkoxysilane compound.

As the alkoxysilane compound containing an organic functional group as a starting material, the organic functional group may be directly bonded to a silicon atom, or may be bonded to a silicon via a divalent hydrocarbon group having 1 to 10 carbon atoms. It may be bonded to an atom. The number of alkoxyl groups bonded to silicon is preferably two or three. As the compound, conventionally known compounds can be used, and specific examples thereof include the following.

Mercapto group-containing alkoxysilane compounds: γ-mercaptopropyltrimethoxysilane, γ-
Mercaptopropyltriethoxysilane, γ-mercaptopropyltributoxysilane, γ-mercaptopropylmethyldimethoxysilane, γ-mercaptopropylmethyldiethoxysilane, β-mercaptomethylphenylethyltrimethoxysilane, mercaptomethyltrimethoxysilane, 6-mercapto Hexyltrimethoxysilane, 10-mercaptodecyltrimethoxysilane, etc. Epoxy group-containing alkoxysilane compounds: γ-glycidoxypropyltrimethoxysilane, γ-glycidoxypropyltriethoxysilane, γ-glycidoxypropyltributoxysilane, γ-glycidoxypropyltriisopropenoxysilane, γ-glycidoxypropylmethyldimethoxysilane, γ-glycidoxypropylmethyldiethoxysilane, β- (3 4-epoxycyclohexyl) ethyltrimethoxysilane, beta-(3,4-epoxycyclohexyl) ethyl triethoxysilane, beta-
(3,4-epoxycyclohexyl) ethylmethyldimethoxysilane, β- (3,4-epoxycyclohexyl) ethylmethyldiethoxysilane, 5,6-epoxyhexyltrimethoxysilane, 9,10-epoxydecyltrimethoxysilane, etc. (Meth) acryloyl group-containing alkoxysilane compound:
γ-methacryloxypropyltrimethoxysilane, γ-
Methacryloxypropyltriethoxysilane, γ-methacryloxypropyltributoxysilane, γ-methacryloxypropylmethyldimethoxysilane, γ-methacryloxypropylmethyldiethoxysilane, γ-acryloxypropyltrimethoxysilane, γ-acryloxypropyltri Ethoxysilane, γ-acryloxypropylmethyldimethoxysilane, γ-methacryloxymethyltrimethoxysilane, γ-acryloxymethyltrimethoxysilane, etc. Vinyl group-containing alkoxysilane compounds: vinyltrimethoxysilane, vinyltriethoxysilane, vinyltributoxy Silane, vinylmethyldimethoxysilane, 5-hexenyltrimethoxysilane, 9-decenyltrimethoxysilane, styryltrimethoxysilane, etc. Kishishiran compounds: .gamma.-chloropropyl trimethoxy silane, .gamma.-bromopropyl trimethoxy silane, trifluoropropyl trimethoxy silane, nonafluorohexyl trimethoxysilane, gamma
Aminopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-aminopropyltributoxysilane, γ-aminopropylmethyldimethoxysilane, γ-aminopropylmethyldiethoxysilane, etc. Amino group-containing alkoxysilane compound: N- ( β-aminoethyl) -γ-aminopropyltrimethoxysilane,
N- (β-aminoethyl) -γ-aminopropyltriethoxysilane, N- (β-aminoethyl) -γ-aminopropyltributoxysilane, N- (β-aminoethyl) -γ-aminopropylmethyldimethoxysilane , N
-Phenyl-γ-aminopropyltrimethoxysilane and the like These organic functional group alkoxysilane compounds may be used alone or as a mixture of two or more.

Among these compounds, it is preferable to use a mercapto group-containing alkoxysilane or an epoxy group-containing alkoxysilane because of excellent coating performance such as stain resistance and durability.

The organic functional group forms a chemical bond with an organic resin of a coating material by a chemical reaction, forms a hydrogen bond by a polar structure, or forms an interaction based on affinity from a silicone compound coating film. It functions to prevent detachment.

As the other starting material, the tetraalkoxysilane compound (b) includes, for example, tetramethoxysilane, tetraethoxysilane, tetraisopropoxysilane and tetrabutoxysilane. These compounds can be used alone or in combination of two or more. Among these, the alkoxysilane group is easily hydrolyzed to generate a silanol group, and since a coating film having excellent stain resistance is formed, it is possible to use tetramethoxysilane and tetraethoxysilane.
Particularly preferred.

The mixing ratio of the organic functional group-containing alkoxysilane compound and the tetraalkoxysilane compound is such that tetraalkoxysilane is 20 to 2,000 per 100 parts by weight of the epoxy functional group-containing alkoxysilane.
It is preferable to use a ratio satisfying the range of parts by weight. 2
If the amount is less than 0 part by weight, the hydrophilicity of the co-hydrolysis condensate is reduced, and the desired stain resistance, acid resistance, etc. are inferior. On the other hand, if it exceeds 2,000 parts by weight, the affinity with the organic resin, the reactivity becomes poor, the ability to fix the present silicone compound in the coating film becomes insufficient, and it is easy to drop off from the coating film after hydrolysis. Not preferred. Furthermore, 50 to 1,0
It is particularly preferred to satisfy the range of 00 parts by weight.

The silicone compound (A) used in the present invention I preferably has an average degree of polymerization of 3 to 100. If the degree of polymerization is less than 3, it is not preferable because it volatilizes, sufficient hydrophilicity cannot be imparted to the surface of the coating film, or easily elutes from the coating film. On the other hand, when the degree of polymerization is 1
If it exceeds 00, the silicone is poorly dispersed in the coating film,
It is not preferable because formation of a uniform coating film becomes difficult. Further, the degree of polymerization is preferably in the range of 5 to 80.

The method for producing the silicone compound (A) is based on a conventionally known method. For example, in the presence of a hydrolysis catalyst, a mixture of the above-mentioned epoxy-functional alkoxysilane compound and tetraalkoxysilane compound is prepared.
It can be obtained by adding water and performing a partial cohydrolysis condensation reaction.

In the partial co-hydrolysis condensation, the degree of partial co-hydrolysis is, for example, that the average degree of polymerization is 0 when no hydrolysis is performed, and that the degree of polymerization is too high when 100% is hydrolyzed. The degree of polymerization is closely related to the degree of polymerization, and the average degree of polymerization is adjusted to 3 to 100 in the silicone compound used in the present invention.

As the hydrolysis / condensation catalyst to be used, various conventionally known catalysts can be used. Specific examples include, for example, organic acids such as acetic acid, butyric acid, maleic acid and citric acid; inorganic acids such as hydrochloric acid, nitric acid, phosphoric acid and sulfuric acid; basic compounds such as triethylamine; tetrabutyl titanate, dibutyltin dilaurate and the like. Organic metal salts; F-containing compounds such as KF and NH4F. The above catalysts may be used alone or in combination of two or more. The amount of catalyst used is 0.0001
Is preferably in the range of １1 mol%.

Among these catalysts, the F-containing compounds are excellent in the function of accelerating the condensation of silanol groups having high reaction activity, and are therefore suitable for synthesizing products containing only a small amount of silanol groups. It is particularly preferable to use the paint itself because the storage stability of the paint becomes good.

In carrying out the partial cohydrolysis condensation reaction, an organic solvent may be used as necessary. Examples of usable organic solvents include, for example, methanol, ethanol,
Alcohols such as isopropanol and t-butanol;
Examples include ketones such as acetone and methyl isobutyl ketone; ethers such as dibutyl ether; esters such as ethyl acetate; and aromatics such as toluene.
Particularly, organic solvents such as methanol, ethanol, and acetone are preferable.

The amount of water used in the partial cohydrolysis condensation reaction is determined depending on the desired degree of polymerization. Excessive addition destroys the alkoxy group and eventually leads to gelation, so it must be determined strictly. In particular, when an F-containing compound is used as a catalyst, the F-containing compound has the ability to completely promote hydrolytic condensation, and thus the degree of polymerization can be determined by the amount of water to be added, and any molecular weight can be set, which is preferable. . That is, in order to prepare a target product having an average degree of polymerization M,
What is necessary is just to use (M-1) mol of water with respect to M mol of alkoxysilane compounds. In the case of other catalysts, it is necessary to slightly increase the amount.

The partial cohydrolysis condensation reaction is carried out at room temperature or at room temperature.
It can be performed in a temperature range of 50 ° C. or less. When the temperature is lower than room temperature, the progress of the reaction is slowed down, which is not practical. On the other hand, when the temperature is higher than 150 ° C., thermal decomposition of an organic substituent such as an epoxy group occurs.

The mixing ratio of the silicone compound (A) is based on the acid epoxy-curable resin of the acid epoxy-curable coating composition (including the alkoxyl group-containing vinyl (co) polymer when it is blended). The range is 0.1 to 50 parts by weight, preferably 1.0 to 20 parts by weight, per 100 parts by weight. If the compounding ratio is less than 0.1 part by weight, the stain resistance of the coating film cannot be sufficiently obtained. On the other hand, if it exceeds 50 parts by weight, the water resistance, acid resistance, alkali resistance, etc. of the coating film are deteriorated. Absent.

The present invention II: The hydrolyzable groups in (1) to (3) of the silicone resin (B) used in the present invention II are as follows:
Those conventionally known, for example, methoxy group, ethoxy group,
Examples include a propoxy group, an isopropenoxy group, an acetoxy group, and a butanoxime group. These hydrolyzable groups can be contained alone or in combination of two or more. A methoxy group and an ethoxy group are particularly preferred because they have good storage stability of the coating material and can exhibit stain resistance early because of their excellent hydrolyzability.

The silicone resin (B) used in the present invention II
The organic substituent represented by R2 in (1) to (3) has 1 to 3 carbon atoms, and is preferably, for example, a methyl group, an ethyl group, or a propyl group. Among them, the methyl group has the least hydrophobicity, and thus exhibits an effect excellent in stain resistance.

The silicone compound (B) used in the present invention II has an organic functional group (R) in the (1) silicon structural unit.
1) a silicone compound (B) which forms a chemical bond with an organic resin by a chemical reaction, forms a hydrogen bond by a polar structure, or interacts based on affinity;
This functions to prevent desorption from the coating film. The organic functional group may be directly bonded to silicon, or may be bonded to silicon via an organic substituent.

The organic functional groups include, for example, γ-glycidoxypropyl group, β- (3,4-epoxycyclohexyl) -ethyl group, 5,6-epoxyhexyl group, 9,
Epoxy groups such as 10-epoxydecyl group; mercapto groups such as γ-mercaptopropyl group, β- (mercaptomethylphenyl) ethyl group, 6-mercaptohexyl group, 10-mercaptodecyl group and mercaptomethyl group; γ-methacrylic acid (Meth) acryloyl groups such as roxypropyl group, γ-methacryloxymethyl group, γ-acryloxypropyl group and γ-acryloxymethyl group; γ-chloropropyl group, γ-bromopropyl group, trifluoropropyl group and the like And a vinyl group, an amino group and the like. These organic functional groups can be contained alone or in combination of two or more.

The silicon structural unit containing these organic functional groups has two (D units) or three (T1) hydrolyzable groups capable of forming a siloxane bond by a hydrolytic condensation reaction.
Units) can be used.

The content of these silicon structural units containing an organic functional group is in the range of 5 to 80 mol% based on all silicon atoms in the silicone compound (B). Content is 5
If the amount is less than mol%, the ability to fix the silicone compound (B) in the coating film is insufficient, and the silicone compound (B) tends to elute from the coating film, which is not preferable. On the other hand, if the content exceeds 80 mol%, the hydrophilicity of the present silicone compound (B) becomes insufficient, and good stain resistance cannot be obtained, which is not preferable. A particularly preferred content is in the range of 10 to 50 mol%.

In the silicone compound (B), (2)
The silicon structural unit (T2 unit) represented by the general formula R2SiZ3 of formula (1) finally forms a silanol group or contains three hydrolyzable groups capable of condensing with another silicon atom to form a siloxane bond. It is a unit that can impart flexibility and flexibility without significantly lowering the hydrophilicity of the coating film. When this unit is not contained, there is a disadvantage that the partial cross-linking of the coating film becomes high in density and cracks are generated in the coating film.

The content of T2 as a silicon structural unit is in the range of 0.1 to 30 mol% (based on total silicon atoms) in the silicone compound (B). If the content is less than 0.1 mol%, flexibility is not imparted to the coating film, cracks and the like are generated, and a good coating film cannot be obtained, which is not preferable. On the other hand, if the content exceeds 30 mol%, although sufficient flexibility is imparted, the hydrophobicity becomes too strong, resulting in insufficient hydrophilicity and poor stain resistance, which is not preferable. Further, the content of the T2 unit is preferably in the range of 1 to 25 mol%.

In the silicone compound (B), the silicon structural unit (Q unit) represented by the general formula SiZ4 is
Finally, it is a unit containing four hydrolyzable groups capable of forming a silanol group or condensing with another silicon atom to form a siloxane bond, and is a unit capable of imparting hydrophilicity to a coating film.

The content of the Q unit is in the range of 10 to 94.9 mol% (based on total silicon atoms) in the silicone compound (B). If the content is less than 10 mol%, the hydrophilicity becomes insufficient, so that good stain resistance, acid resistance, alkali resistance, and the like cannot be obtained. On the other hand, when the content exceeds 94.9 mol%, although hydrophilicity is sufficiently imparted, the hydrophilicity increases, and the silicone compound easily falls off from the coating film, and the characteristics deteriorate over time, which is not preferable. Further, the content of the Q unit is 25 to 90 mol%.
Is preferable.

In the silicone compound (B),
The total content of the T2 unit and the Q unit is the amount excluding the content of the organic functional group-containing silicon structural unit, and is 20 to 9
The range is 5 mol%.

The degree of polymerization of the silicone compound (B) is from 3 to
The range is 100. When the degree of polymerization is less than 3, the silicone compound (B) volatilizes from the coating film during the curing process of the coating film, the hydrophilicity cannot be imparted to the coating film surface, and the silicone compound (B) is easily eluted from the coating film. As a result, a coating film having excellent stain resistance and durability cannot be formed. Further, the degree of polymerization is 100
When it exceeds, the silicone compound (B) disperses poorly in the coating film, and it becomes difficult to form a uniform coating film, so that the finish property,
Poor stain resistance, durability, etc. Further, the degree of polymerization is preferably in the range of 5 to 80.

The silicone compound (B) can be produced by various conventionally known methods as long as the above conditions are satisfied. Specifically, the following examples can be given, but the method is not limited to the methods described below.

(A) Silane coupling agent [component having (1) unit, hereinafter the same meaning], alkyl trifunctional silane [component having (2) unit, (T2 unit)
Hereinafter, the meaning is the same], and a tetrafunctional silane [(3)
Component having unit, (Q unit) Hereinafter, the same meaning is used.]
In the presence of a hydrolysis-condensation catalyst.

(B) An oligomer or resin obtained by partially co-hydrolyzing an alkyl trifunctional silane and a tetrafunctional silane is reacted with a silane coupling agent or a preliminary hydrolyzate.

(C) Silane coupling agent and alkyl 3
The co-hydrolyzate with the functional silane is reacted with a tetrafunctional silane or a partially hydrolyzed product thereof.

Among these methods, the method of partially co-hydrolyzing and condensing the starting silane compound (a) is based on an organic functional group,
T units and Q units can be uniformly introduced into the silicone compound (B) to improve coating film performance such as stain resistance, acid resistance, and alkali resistance, and to improve their durability performance, and to prevent cracking of the coating film. Is particularly preferable because it is easy to achieve both.

In the partial co-hydrolysis condensation, the degree of partial co-hydrolysis is, for example, that the average degree of polymerization is 0 when no hydrolysis is performed and that the degree of polymerization is too high when 100% hydrolysis is performed. The silicone compound (B) used in the present invention is adjusted to have an average degree of polymerization of 3 to 100, since the degree of polymerization is closely related to the degree of polymerization so as to cause gelation.

As the silane coupling agent, alkyl trifunctional silane and tetrafunctional silane as starting materials, conventionally known ones can be used as long as the substituent and the hydrolyzable group satisfy the above conditions. . The silane coupling agent is trifunctional (T1 unit) and bifunctional (D1 unit).
Unit) can be used.

For the production of the silicone compound (B), a method similar to that of the silicone compound (A) described above (after dilution with the solvent, if necessary, blending the hydrolysis catalyst and water in the above range, The partial hydrolysis condensation reaction is carried out at room temperature or a temperature range of 150 ° C. or lower).

The mixing ratio of the silicone compound (B) is based on 100 parts by weight of the solid content of the resin of the acid epoxy-curable coating composition (including the alkoxyl group-containing vinyl (co) polymer when it is mixed). 0.1 to 50 parts by weight,
Preferably, the range is 1.0 to 20 parts by weight. If the compounding ratio is less than 0.1 part by weight, the stain resistance of the coating film, acid resistance, alkali resistance, and performance such as water resistance are reduced, while if more than 50 parts by weight, the water resistance of the coating film, It is not preferable because acid resistance and alkali resistance are deteriorated.

When the coating film formed by the coating composition of the present invention is exposed outdoors, the water contact angle gradually decreases due to the action of rain or the like, but the surface of the coating film before the exposure is subjected to an acidic treatment (2). Immersed in 0.5% by weight sulfuric acid aqueous solution at 20 ° C. for 24 hours, and then the attached sulfuric acid aqueous solution was washed with water and dried.) The final contact angle of the exposed coating film was estimated by measuring the water contact angle. can do.

In the coating composition of the present invention, the surface of the formed coating film is treated with an acid (immersed in a 2.5% by weight sulfuric acid solution at 20 ° C. for 24 hours, and then the attached sulfuric acid solution is washed with water and dried. However, the surface of the coating film preferably has a contact angle with water, preferably in the range of 10 to 70. Contact angle is 7
If it exceeds 0 degree, the stain resistance decreases, which is not preferable.
If the contact angle is less than 10 degrees, the water resistance, acid resistance, alkali resistance and the like of the coating film are undesirably reduced.

When the coating film formed by the coating composition of the present invention is exposed outdoors, the water contact angle gradually decreases due to the action of rain or the like, but the surface of the coating film before exposure is subjected to an acidic treatment (2). Immersed in 0.5% by weight sulfuric acid aqueous solution at 20 ° C. for 24 hours, and then the attached sulfuric acid aqueous solution was washed with water and dried.) The final contact angle of the exposed coating film was estimated by measuring the water contact angle. can do.

The coating composition of the present invention can be formed by applying the above-described coating composition to a substrate and heating to form a coating film. The coating composition is used as a topcoat. As the base material, steel, aluminum, zinc, stainless steel,
Metal substrates such as galvanized steel sheets and those obtained by subjecting these to surface treatment with chromic acid, zinc phosphate or the like can be used.
Further, the present invention can also be applied to a substrate obtained by applying a primer coating such as (cation) electrodeposition primer coating and intermediate coating to these metal base materials.

The coating composition of the present invention can be used not only as a colored top coating composition, but also as a top clear coating composition. As the clear top coating composition, no metallic pigment (for example, flaky aluminum powder, copper powder, nickel powder, stainless steel powder, colored mica powder, etc.) or other colored pigments are blended in the composition or completely. Can be used so as not to be concealed.

Examples of the use of the clear top coating composition include, for example, a curable resin composition (for example, an acrylic resin, a polyester resin, an alkyd resin, an epoxy resin) Conventional automobiles obtained by blending a crosslinking agent (for example, an amino resin, a blocked polyisocyanate compound, a polycarboxylic acid compound, a silane compound, etc.) with a base resin such as a resin, and a metaclick pigment (the same as described above). After applying a known organic solvent or water-based metallic base coating composition used in the field of, if necessary, a clear coating composition (first clear, for example, in the above base coating composition, a metallic pigment Or other color pigments are not blended at all or blended to the extent that they do not completely hide) It can be carried out by coating a topcoat coating composition of the present invention.

Examples of the coating method using the overcoat composition include, for example, a two-coat one-bake method (base coating composition / topcoat composition), a two-coat two-bake method (same as left), and a three-coat method known in the field of automobiles. Coating 1 baking method (base coating composition / first clear coating composition / top coating composition), 3 coating 2 baking method (same left), and 3 coating 3 baking method (same left) can be mentioned.

The method for applying the top coat composition can be carried out, for example, by spray coating. The coating amount is generally in the range of about 1 to 80 μm, preferably about 10 to 60 μm. In addition, the baking of the coating film is generally 130 to
At a temperature of 200 ° C. for about 10-60 minutes, preferably about 20
４０40 minutes.

[0066]

【Example】

Preparation of Acid-Epoxy-Curable Coating Composition I. Preparation Example of Acid-Epoxy-Curable Coating Composition I Epoxy- and hydroxyl-containing acrylic copolymer solution (glycidyl methacrylate / 2-hydroxyethyl acrylate / n-butyl acrylate / γ- Methacryloxypropyltrimethoxysilane / styrene = 35/1
(5/15/15/20% by weight copolymer, number average molecular weight 2,000, solid content 70% by weight xylene solution, epoxy group content 2.12 mmol / g, hydroxyl value 78 mg KOH / g)
96 g of a carboxyl group-containing compound solution (methanol half-esterified maleic anhydride / 2-hydroxyethyl acrylate / n-butyl acrylate / styrene =
20/20/40/20% by weight, number average molecular weight 3,50
0, a solid content of 55% by weight, and an acid value of 86 mgKOH / g) (60 g) to give a coating composition I.

Preparation Example of Acid Epoxy-Curable Coating Composition II In the coating composition I, an acrylidyl methacrylate / epoxy / hydroxyl group-containing acrylic copolymer solution was used.
2-hydroxyethyl acrylate / n-butyl acrylate / methyl methacrylate / styrene = 35/15
/ 15/15/20 wt% copolymer, number average molecular weight 2,000, solid content 70 wt% xylene solution, epoxy group content 2.12 mmol / g, hydroxyl value 78 mgKOH / g
A coating composition II was obtained in the same manner as the coating composition I, except that the above composition was used.

Preparation of Silicone Compound Containing Mercapto Functional Group and Alkoxy Group Preparation Example of Silicone Compound A1-1 1,000 ml equipped with a thermometer, nitrogen inlet tube and dropping funnel
196 g (1.00 mol) of γ-mercaptopropyltrimethoxysilane (a), 152 g (1.00 mol) of tetramethoxysilane, and 320 g of methanol
(10 mol) and 0.06 g (0.001 mol) of KF were charged, and 28.8 g (1.60 mol) of water was slowly added dropwise at room temperature with stirring. After completion of the dropwise addition, the mixture was stirred at room temperature for 3 hours, and then heated and stirred for 2 hours under methanol reflux. Thereafter, low-boiling components were distilled off under reduced pressure and filtered to obtain 231 g of a colorless transparent liquid.

As a result of GPC measurement of the substance thus obtained, the average degree of polymerization was 5.4 (set degree of polymerization = 5.0), which was almost as set.

When the amount of the alkoxy group was determined by the alkali cracking method, it was 42.0% by weight (set value: 42.9% by weight), and it was confirmed that the alkoxy group remained as set.

The amount of active hydrogen determined by the methyl Grignard reagent was determined to be 3.51 × 10 −3 mol / g (the amount of active hydrogen derived from mercapto groups (set value) = 3.64 × 1
0-3 mol / g), and it was confirmed that the mercapto group was also introduced substantially as set.

From the 1H-NMR measurement results (integration ratio between mercapto group and methoxy group), the structure of the obtained substance was as follows, as set.

Average composition formula:

[0074]

Embedded image

The silicone compound thus obtained is referred to as Compound A1-1.

Preparation Examples of Compounds A1-1 to A1-4 and Compounds A1-5 and A1-6 for Comparative Examples In the same manner, the types and set amounts of the mercapto-functional alkoxysilane, tetraalkoxysilane, and catalyst used were determined in the same manner. By changing, compounds A1-1 to A1-4 having a set structure as shown in Table 1 were prepared. In Table 1, A1-1 to A
The amount of 1-4 is expressed in mole.

Further, instead of the partial cohydrolysis-condensation method (hereinafter referred to as Production Method I) in the present invention, the compounds A1-5 and A1
-6 was prepared. In Table 1, the blending amounts of A1-5 and A1-6 are represented by mol.

Comparative Preparation Example A1-5 (Production Method II) Reaction with Tetraalkoxysilane Oligomer: The average silane tetramer was replaced with 1.00 instead of tetramethoxysilane.
mol of water for hydrolysis (1.60-0.75 =
The reaction was carried out in the same manner as in Example 1 using 0.85 mol) and HCl as a catalyst to obtain 228 g of compound A1-5 which was a colorless transparent liquid.

The amount of active hydrogen was measured and found to be 4.66 ×
10-3 mol / g, and the mercapto group was not completely introduced.

Further, as a result of GPC measurement, a molecular weight distribution mainly composed of two peaks was observed, and it was understood that the present reaction product lacked uniformity.

Comparative Preparation Example A1-6 (Production Method III) Preparation by reaction of a tetraalkoxysilane oligomer with a silane coupling agent oligomer: 1.00 mol of an average tetramer of the same silane was used instead of tetramethoxysilane. Further, instead of γ-mercaptopropyltrimethoxysilane, a product obtained by previously hydrolyzing the same silane with 3.00 mol of water was used, and HCl was used as a catalyst. As a result, 242 g of a compound A1-6 which was a colorless transparent liquid was obtained.

The amount of active hydrogen was measured and found to be 3.68 ×
10-3 mol / g, and the mercapto group was almost completely introduced. However, as a result of GPC measurement, the average degree of polymerization was as high as 49.

The above-mentioned silicone compounds A1-1 to A1-6
Table 1 summarizes the amounts (moles) of, the production methods and the special values of the compounds.

[0084]

[Table 1]

Preparation of Silicone Compound Containing Epoxy Functional Group and Alkoxy Group: Preparation of Silicone Compound A2-1 2,000 ml equipped with a thermometer, nitrogen inlet tube and dropping funnel
236 g (1.00 mol) of γ-glycidoxypropyltrimethoxysilane (b), 152 g (1.00 mol) of tetramethoxysilane, and 320 g of methanol
(10 mol) and 0.06 g (0.001 mol) of KF, and 28.8 g (1.60 mol) of water were slowly added dropwise at room temperature with stirring. After completion of the dropwise addition, the mixture was stirred at room temperature for 3 hours, and then heated and stirred for 2 hours under methanol reflux. Thereafter, low-boiling components were distilled off under reduced pressure and filtered to obtain 266 g of a colorless transparent liquid.

As a result of GPC measurement of the substance thus obtained, the average degree of polymerization was 5.3 (set degree of polymerization = 5.0), which was almost as set.

When the epoxy equivalent was measured by an epoxy ring opening method using hydrochloric acid, it was 319 g / mol (set value: 314
g / mol), and it was confirmed that a predetermined amount of epoxy groups had been introduced. When the amount of the alkoxy group was determined by the alkali cracking method, it was 36.8% by weight (set value: 37.4% by weight), and it was confirmed that the alkoxy group still remained as set.

From the results of 1H-NMR measurement, the structure of the obtained substance was as follows, as set.

Average composition formula:

[0090]

Embedded image

The silicone compound thus obtained is referred to as Compound A2-1.

Further, instead of the partial cohydrolysis-condensation method (hereinafter referred to as Production Method I) in the present invention, compounds A2-2 and A2-3 for comparative examples were prepared by the following production method with the blending in Table 2. . In Table 1, the blending amounts of A2-2 and A2-3 are represented by mol.

Comparative Preparation Example A2-2 (Production Method II) Reaction with Tetraalkoxysilane Oligomer: An average tetramer of the same silane was used in place of tetramethoxysilane for 1.0 hour.
0 mol was used, and water for hydrolysis was used (1.60-0.75 =
Using 0.85 mol) of HCl as a catalyst and carrying out the reaction in the same manner as in A2-1, 258 g of a colorless transparent liquid compound A2-1 was obtained.

When the epoxy equivalent was measured, it was 429 g /
The mol and epoxy groups were slightly destroyed.

As a result of GPC measurement, a molecular weight distribution consisting mainly of two peaks was observed, indicating that the reaction product lacked uniformity.

Comparative Preparation Example A2-3 (Production Method III) Preparation by reaction of tetraalkoxysilane oligomer with silane coupling agent oligomer: 1.00 mol of an average tetramer of the same silane was used instead of tetramethoxysilane. In place of γ-glycidoxypropyltrimethoxysilane (b), a silane obtained by previously hydrolyzing the silane with 3.00 mol of water is used.
And 271 g of a colorless transparent liquid compound A2-3 was obtained by carrying out a reaction in the same manner as in A2-1.

The epoxy equivalent was measured to be 693 g /
In mol, much less than the setting was introduced. However, as a result of GPC measurement, the average degree of polymerization was 4
It was quite high at 4.

The above silicone compounds A2-2 to A2-3
Table 2 summarizes the compounding amount (mole), production method and special values of the compounds.

[0099]

[Table 2]

Preparation of Silicone Compound Containing Epoxy Group and Alkoxy Group Preparation Example of Silicone Compound B1-1 1,000 ml equipped with a thermometer, nitrogen inlet tube and dropping funnel
, 47.3 g (0.20 mol) of γ-glycidoxypropyltrimethoxysilane, 114.0 g (0.75 mol) of tetramethoxysilane, 6.8 g (0.05 mol) of methyltrimethoxysilane, and 160
g (5 mol) and 0.06 g (0.001 mol) of KF were added, and 17.1 g (0.95 mol) of water was slowly added dropwise at room temperature with stirring. After completion of the dropwise addition, the mixture was stirred at room temperature for 3 hours, and then heated and stirred for 2 hours under methanol reflux. Thereafter, low-boiling components were distilled off under reduced pressure and filtered to obtain 113 g of a colorless and transparent liquid.
Obtained.

As a result of GPC measurement of the thus obtained substance, the average degree of polymerization was 20.5 (set degree of polymerization = 20), which was almost as set.

When the epoxy equivalent was measured by an epoxy ring-opening method using hydrochloric acid, it was 625 g / mol (set value: 622 g / mol).
g / mol), and it was confirmed that a predetermined amount of epoxy groups had been introduced. When the amount of the alkoxy group was determined by the alkali cracking method, 45.5% (theoretical value: 46.1%)
Met.

From the result of 1H-NMR measurement, the structure of the obtained substance was a structure represented by the following average composition formula.

Average composition formula:

[0105]

Embedded image

The silicone compound thus obtained is referred to as Compound B1-1.

Preparation Examples of Silicone Compound B1-2 and Comparative Example Compound B1-5 Silicone compound B1-2 and Comparative Example Compound B1-5 were prepared in the same manner as described below in amounts shown in Table 3. .

Instead of the partial cohydrolysis condensation method (hereinafter referred to as Production Method I), the following production method was also studied.

Silicone Compound B1-3 (Production Method II) In advance, an organic functional group-containing alkoxysilane and a T unit alkoxysilane are co-hydrolyzed, and then a condensation reaction is performed with tetraalkoxysilane.

Silicone Compound B1-4 (Production Method III)
In advance, a tetraalkoxysilane and a T unit alkoxysilane are co-hydrolyzed, and then a condensation reaction is performed with an organic functional group-containing alkoxysilane.

Compound B1-6 for Comparative Example (Production Method IV) After each component is hydrolyzed in advance, the components are mixed and subjected to a condensation reaction.

The above silicone compounds B1-1 to B1-6
Table 3 summarizes the amounts (moles) of, the production methods and the special values of the compounds.

[0113]

[Table 3]

Examples 1 to 12 and Comparative Examples 1 to 9 After mixing the coating composition and the silicone compound in the composition (solid content, g) shown in Table 4, 1 g of tetrabutylammonium bromide was added to 100 g of the resin. And a swollen 1000 (Cosmo Oil Co., Ltd .; trade name) having a viscosity of 2
It was adjusted to 5 seconds (Ford Cup No. 4/20 ° C.) to obtain paints of Examples and Comparative Examples.

Using the obtained paint as a clear top coat paint, an overcoating film of two coats and one bake was formed as follows.

0.8 mm thick with zinc phosphate chemical conversion treatment
An epoxy-based cationic electrodeposition paint is electrodeposited on a dull steel sheet to a dry film thickness of about 20 μm, baked at 170 ° C. for 20 minutes, sharpened with a # 400 sandpaper, and degreased with petroleum benzene. Then, an intermediate coating surfacer for automobiles is applied by air spraying so as to have a dry film thickness of about 25 μm, and baked at 140 ° C. for 30 minutes.
The material was sanded with a sandpaper of No. 00, drained and dried, and then wiped with petroleum benzene to degrease it to obtain a test material.

Next, coloring (metallic) is applied to this material.
A base coat paint is applied so as to have a cured film thickness of 20 μm, and is forcibly dried at 80 ° C. for 10 minutes.
m and heated at 140 ° C. for 30 minutes to cure both coatings to form a topcoat coating.

Table 4 shows the results.

[0119]

[Table 4]

Coating surface smoothness: The coating surface condition was visually observed and judged according to the following evaluation criteria. ◎ indicates that the smoothness was good without any peeling, unevenness, etc., and x indicates that the smoothness was poor with the peeling, unevenness, etc., respectively.

Coating surface gloss: JIS K-5400 7.6
(1990) (reflection angle: 60 degrees).

Acid resistance: 0.5 ml of a 40% sulfuric acid aqueous solution was dropped on the coated surface, heated at 70 ° C. for 20 minutes, washed with water, and the state of the coated surface was evaluated. Four levels of ◎, △, △, and × were determined in order from good to bad according to the degree of abnormality (◎) without any abnormality (◎) and abnormality (×) such as marked gloss or blister.

Water contact angle after acid treatment: The test plate was immersed in 2.5% sulfuric acid at 20 ° C. for 24 hours, and the attached sulfuric acid was washed with water and dried, and then manufactured by Kyowa Chemical Co., Ltd. Using a contact angle meter DCAA, a drop of 0.03 cc of deionized water was dropped on the surface of the coating film, and the value was measured after 3 minutes at 20 ° C.

Outdoor exposure test: A test plate was installed at an angle of 30 ° on the south side of Kansai Paint Co., Ltd., Tokyo Plant. Respectively,
The test plate exposed for 3 months and 6 months was evaluated for coating film properties without adjusting the sample such as washing with water. Appearance (dirt): The degree of dirt on the coated surface was evaluated. And no change in dirt ○ = very slight change in dirt on the coated plate before test ○-= slight dirt change on the coated plate before test △ = coated plate before test ×: Those with a significant change in stain on the coated plate before the test. Initial water contact angle: The same method as that without sample preparation (immersion in sulfuric acid, washing with water, etc.) Was measured.

[0125]

According to the present invention, since a specific silicate compound is blended with an acid-curable coating, a coating film excellent in stain resistance which is free from car washing can be obtained.

Claims (4)

[Claims] 1. The acid epoxy-curable coating composition contains (1) at least one organic functional group selected from a mercapto group, an epoxy group, a (meth) acryloyl group, a vinyl group, a haloalkyl group and an amino group. A silicone compound (A) which is a partially hydrolyzed condensate of a silane mixture of 100 parts by weight of an alkoxysilane compound (a) and (2) a tetraalkoxysilane compound (b) of 20 to 2,000 parts by weight. A topcoat composition comprising: 2. An acid-epoxy curable coating composition comprising: (1) a compound represented by the following general formula: R1 R2 SiZ2 (where R1 is an epoxy group, a mercapto group,
Represents an organic functional group such as an acryloyl group, a vinyl group, a haloalkyl group or an amino group, R2 represents an alkyl group having 1 to 3 carbon atoms, and Z is bonded to another silicon atom by a hydrolyzable group or a siloxane bond. A D unit as a silicon structural unit represented by the following formula: and / or a T1 unit as a silicon structural unit represented by the general formula R1SiZ3 (wherein R1 and Z have the same meanings as described above). ~ 80
(2) 0.1% of a T2 unit as a silicon structural unit represented by the general formula R2SiZ3 (wherein R2 and Z have the same meanings as described above).
(3) containing 10 to 94.9 mol% of a Q unit as a silicon structural unit represented by the general formula SiZ4 (wherein Z has the same meaning as described above); When the total amount of the T2 unit and the Q unit is 20 to 95
An overcoat composition comprising a silicone compound (B) having an organic functional group and a hydrolyzable group in one molecule of 3 to 100 mol% of an average degree of polymerization. 3. The top coating composition according to claim 1, wherein the organic functional group of R1 represented by the general formula R1 R2 SiZ2 is a mercapto group. 4. The acid epoxy-curable coating composition is an acid epoxysilane-curable coating composition obtained by blending an alkoxysilyl group-containing vinyl (co) polymer with the coating composition. Item 7. A top coating composition according to item 1, 2 or 3.