JPH09143425A - Curable coating composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a new curable coating composition excellent in preservation stability in a single liquid, and performances such as curability at a low temperature, finishing properties and corrosion resistivity by blending a specific amount of a specific cation polymerization catalyst. SOLUTION: This curable coating composition comprises (A) 100 pts.wt. resin mixture containing a reactive silicon group, hydroxyl group and an epoxy group as essential functional group components, (B) 0.1-5 pts.wt. metal chelate catalyst and (C) 0.1-5 pts.wt. cation catalyst of aromatic sulfonium salt expressed by formula I R<1> is H, OH, an alkoxyl, or formula II [Y is a (substituted)alkyl, etc.,]; R<2> and R<3> are each H, a halogen or an alkyl; R<4> and R<5> are each an alkyl, an aralkyl or aryl which can be substituted; X<-> is SbF6 <-> , PF6 <-> , AsF6 <-> or BF4 <-> }. As the component C, e.g. benzyl-4-hydroxyphenylmethyl sulfonium hexafluoroantimonate, etc., can be used.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a novel curable coating composition.

[0002]

2. Description of the Related Art Conventionally, a curable coating composition prepared by blending a resin containing an alkoxysilane group, a hydroxyl group and an epoxy group as a functional group component with a metal chelate catalyst such as aluminum, zirconium or titanium has been disclosed. 63-108
It is publicly known as described in JP-A-048, JP-A-63-108049 and the like. However, the coating composition has a drawback that it does not have sufficient anticorrosion properties for steel sheets.

Further, a composition containing a tin silicate catalyst in place of the above metal chelate has a drawback that the corrosion resistance is improved but the low temperature curability is poor.

[0004]

DISCLOSURE OF THE INVENTION The present invention has developed a paint which satisfies both the anticorrosion property and the low temperature curability which are the drawbacks of a curable paint composition containing an alkoxysilane group, a hydroxyl group and an epoxy group as a functional group component. It was made for the purpose of doing.

[0005]

Means for Solving the Problems As a result of intensive studies to solve the above-mentioned problems, the present inventors have found that a resin containing a reactive silicon group, a hydroxyl group and an epoxy group as an essential functional group component. The inventors have found that a composition containing a metal chelate and a specific cationic polymerization catalyst in a specific amount exerts excellent performances in corrosion resistance and low temperature curability, and have completed the present invention.

That is, the present invention contains the following component (A) reactive silicon group, hydroxyl group and epoxy group as essential functional group components, and these functional groups are the same or different resins contained in the molecule. Resin mixture contained 100 parts by weight (B) Metal chelate catalyst 0.1 to 5 parts by weight (C) General formula (1)

[0007]

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(In the formula, R ¹ is a hydrogen atom, a hydroxyl group, an alkoxyl group, or

[0009]

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And Y is an optionally substituted alkyl group, alkoxyl group, phenyl group or phenoxy group, and R is^TwoAnd R^ThreeEach represents a hydrogen atom, a halogen atom or an alkyl group, and R^FourAnd R^FiveRepresents an optionally substituted alkyl group, aralkyl group or aryl group, and X^-Is SbF₆ ^-, PF₆ ^-, AsF₆ ^-Or BF_Four ^- And a cationic polymerization catalyst of an aromatic sulfonium salt of 0.1 to 5 parts by weight.
Wow

Resin (A) used in the coating composition of the present invention
Is a resin or resin mixture containing a reactive silicon group, a hydroxyl group and an epoxy group as essential functional group components.

Examples of the reactive silicon group include a hydroxysilyl group and a hydrolyzable silyl group. The hydrolyzable silyl group is a functional group that forms a hydroxysilulyl group in the presence of water, for example, an alkoxysilyl group,
An acyloxysilyl group and the like are preferred. Among these groups, an alkoxysilyl group is preferable, and a lower alkoxysilyl group such as methoxy and ethoxy is more preferable from the viewpoint of low temperature curability.

The hydroxyl group is a hydroxyl group which is directly bonded to carbon, and primary to tertiary hydroxyl groups can be used, but primary hydroxyl groups are preferred.

As the epoxy group, any of an aliphatic epoxy group such as glycidyl and an alicyclic epoxy group such as 3,4-epoxycyclohexyl can be used.

Examples of the resin (A) include a hydroxyl group-containing resin (a), an epoxy group-containing resin (b),
A resin mixture containing three components of the reactive silicon group-containing resin (c) (hereinafter abbreviated as "resin (1)"), an epoxy group-containing resin (b), and a reactive silicon group-containing resin (c). A mixed resin containing a hydroxyl group in one or both of the resin (b) and the resin (c) components (hereinafter abbreviated as "resin (2)"), hydroxyl group, epoxy group, reaction Examples thereof include a resin containing a conductive silicon group (hereinafter, abbreviated as “resin (3)”).

Resin (1): The hydroxyl group-containing resin (a) has an average of about 2 or more hydroxyl groups in one molecule and preferably has a number average molecular weight of about 1,000 to 100,000, preferably about 3,000 to 80,000. Can be used. If the average number of hydroxyl groups is less than about 2, it is not preferable because the low temperature curability is poor. From the viewpoint of weather resistance and water resistance, the number of hydroxyl groups is preferably about 400 or less on average. If the number average molecular weight is less than 1000, the anticorrosion property, processability, weather resistance, etc. are poor, while if it exceeds 100,000, the compatibility with other components is reduced, and as a result, the curability becomes uneven and the finished appearance,
It is not preferable because the workability is poor.

As the hydroxyl group-containing resin (a), conventionally known resins can be used, but acrylic resins and polyester resins are particularly preferable.

Examples of the hydroxyl group-containing acrylic resin include hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, ethylene glycol mono (meth) acrylate. , Hydroxyl group-containing monomers such as adducts of these monomers and lactones, and other radically polymerizable monomers (for example, methyl (meth) acrylate,
(Ethyl (meth) acrylate, butyl (meth) acrylate, hexyl (meth) acrylate, octyl (meth) acrylate, lauryl (meth) acrylate, cyclohexyl (meth) acrylate and the like ( _C1-24 alkyl or cycloalkyl esters of (meth) acrylic acid, vinyl aromatic compounds such as styrene, perfluorobutylethyl (meth) acrylate, perfluoroisononylethyl (meth) acrylate And perfluoroalkyl (meth) acrylates such as perfluorooctylethyl (meth) acrylate and nitrile compounds such as (meth) acrylonitrile.

Examples of the hydroxyl group-containing polyester resin include polybasic acids (for example, phthalic acid, isophthalic acid, terephthalic acid, succinic acid, sebacic acid, azelaic acid, dimethyl isophthalate, dimethyl terephthalate, etc.) and polyhydric alcohols.
(For example, neopentyl glycol, 1,6-hexanediol, trimethylolpropane, pentaerythritol, etc.) to be obtained by esterification or transesterification so that the hydroxyl group contains Can be used.

The epoxy group-containing resin (b) has an average of about 2 to 300 in one molecule, preferably a number average molecular weight of about 120 to 100,000, preferably about 240 to 6.
0000 can be used. If the number of epoxy groups is less than about 2 on average, low-temperature curability, corrosion resistance and the like deteriorate, while if it exceeds 300, weather resistance and the like deteriorate. It is difficult to obtain those with a molecular weight below 120,
On the other hand, if it exceeds 100,000, the compatibility with other components is poor and the finished appearance of the coating film, low-temperature curing property, anticorrosion property and the like are deteriorated, which is not preferable.

As the epoxy group-containing resin (b), an epoxy group-containing polymerizable unsaturated monomer (for example, JP-A No. 2-1
General formulas (4) to (18) described in JP-A-60879.
Alicyclic vinyl monomers, glycidyl (meth) acrylate homopolymers, etc., or copolymers of these with other radically polymerizable monomers. In addition to the above, an epoxy resin such as ERL4221 (trade name, alicyclic diepoxy compound manufactured by Union Carbide Co.) can also be used.

The reactive silicon group-containing resin (c) is 1
An average of about 1 or more in the molecule, preferably about 2 to 500
Having a number of reactive silicon groups and a number average molecular weight of about 130 to 1
00000, preferably about 700-80,000 can be used. If the number of reactive silicon groups is less than about 1, the low temperature curability is deteriorated, which is not preferable. The molecular weight is about 13
If it is less than 0, it is difficult to obtain, and if it exceeds 100,000, the compatibility with other components is deteriorated, so that the finished appearance of the coating film, low temperature curing property, anticorrosion property, etc. are deteriorated, which is not preferable.

The reactive silicon group-containing resin (c) is a silane monomer (eg, γ- (meth) acryloxypropyltrimethoxysilane, γ- (meth) acryloxypropyltriethoxysilane, vinyltrimethoxysilane). A homopolymer of a silane monomer condensate (for example, a macromonomer condensed with the silane monomer and a trialkoxysilane, for example, a polysiloxane macromonomer described in JP-A-2-160879), or a homopolymer thereof And a copolymer with a radical-polymerizable monomer of. In addition to the above, alkoxysilanes (tetramethoxysilane, trimethoxymethylsilane, tetraethoxysilane, triethoxyethylsilane, trimethoxyphenylsilane, etc.) and their condensates can be used.

The mixing ratio of the above resins (a), (b) and (c) is about 5 to 98% by weight of the resin (a), preferably about 20 to 94, based on the total amount (solid content) of these three components. % By weight, resin (b) about 2-95% by weight, preferably about 5-8
The range of 0% by weight and about 0.1 to 80% by weight, preferably about 1 to 40% by weight of the resin (c) is preferable from the viewpoint of low temperature curing property, anticorrosion property and the like.

Resin (2): The above resin (b) and / or resin (c) into which a hydroxyl group is introduced can be used. In this case, the number of hydroxyl groups contained in one molecule is preferably about 2 or more on average, and preferably about 400 or less on average, for the reasons described above. The resin having a hydroxyl group introduced has a number average molecular weight of about 1,000 to 100,000, preferably about 10
It is preferably from 00 to 80,000. As a method of introducing a hydroxyl group into the resin, for example, it can be produced by using a hydroxyl group-containing unsaturated monomer as an essential component in the production of an acrylic resin. The compounding ratio of the resin is about 5 to 95% by weight, preferably 20 to 80 by total measurement of the two components.
Weight% is preferable from the viewpoint of low temperature curability, anticorrosion and the like. The resin (2) may be blended with the hydroxyl group-containing resin (a), if necessary.

Resin (3): As the resin (3), an average of about 1 or more, preferably about 2 to 500, reactive silicon groups in one molecule, and an average of about 2 to 300 epoxies in one molecule. It is preferable to have a group and an average of about 2 to 200 hydroxyl groups in one molecule from the viewpoint of low-temperature curability, corrosion resistance, and the like.

As the resin (3), for example, the hydroxyl group-containing monomer, the epoxy group-containing polymerizable unsaturated monomer,
A silane monomer (condensate) and, if necessary, a copolymer with the above-mentioned other radically polymerizable monomer can be preferably used. The mixing ratio of the monomer may be such that the functional group in the resin falls within the above range.

The number average molecular weight of the resin is about 1000-100.
000, preferably about 3000 to 80,000 is desirable.

Metal chelate catalyst (B) used in the present invention
Is a catalyst used for promoting the reaction of the hydroxyl group, the epoxy group and the reactive silicon group in the resin (A),
An aluminum chelate compound, a tin silicate compound, a zirconium chelate compound, a titanium chelate compound etc. are mentioned. As a chelating agent, keto-eno
A chelate compound capable of forming a rutile tautomer is preferable.

Specific examples of the metal chelate include, for example,
Tris (ethylacetoacetate) aluminum, tris (propylacetate) aluminum, tris (butylacetoacetate) aluminum, propoxybis (ethylacetoacetate) aluminum, tris (acetylacetonato) aluminum, tris ( Propionylacetonato) aluminum, tris (acetoacetonato) aluminum, tetrakis (ethylacetoacetate)
G) Titanium, tetrakis (acetylacetonato) titanium, dipropoxybis (ethylacetoacetate)
G) Titanium, dipropoxybis (acetylacetonato) titanium, tetrakis (acetylacetonato) zirconium, tetrakis (propylacetoacetate)
Zirconium, tetrakis (ethyl acetoacetate)
Zirconium, monobutyl bis (ethyl acetoacetate
G) tin acetate, monobutylbis (acetylacetonato) tin octate, monobutyltris (ethylacetoacetate) tin, monobutyltris (acetylacetonato) tin, bis (ethylacetoacetate) tin diacetate, Butyl bis (acetylacetonato) tin octate, bis (acetylacetonato) tin dioctate
And the like. These can be used alone or in combination of two or more.

The proportion of the metal chelate (B) is 0.1 to 5 parts by weight, preferably 0.2 to 4 parts by weight, based on 100 parts by weight of the resin (A). If the compounding ratio is less than 0.1, the low-temperature curability, processability, anticorrosiveness, etc. will deteriorate, while if it exceeds 5 parts by weight, the water resistance etc. will deteriorate, such being undesirable.

Cationic polymerization catalyst (C) used in the present invention
Is an aromatic sulfonium salt represented by the general formula (1).

In the general formula (1), the alkoxyl group for R ¹ or Y is C _1-4 such as methyl or ethyl.
C _1-4 such as alkyl group, methoxy group and ethoxy group of
Alkoxy groups are preferred. The Y alkyl group, a methyl group, an alkyl group of C _{1 to 4,} such as ethyl are preferred. Further, as the substituent of the alkyl group or the alkoxyl group which may be substituted in Y of R ^1, a halogen atom or an alkoxyl group may be substituted, and the phenyl group which may be substituted or the substituent of the phenoxy group may be an alkyl group or an alkoxyl group. , Halogen atom, nitro group and the like.

[0034]

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As specific examples of, acetoxy group, methoxycarbonyloxy group, ethoxycarbonyloxy group,
Examples thereof include a benzyloxycarbonyloxy group, a phenoxycarbonyloxy group, and a fluorenylmethoxycarbonyloxy group. As R ¹ , a hydroxyl group is particularly preferable. The alkyl group of R ² or R ³ is preferably a C _1-4 alkyl group such as a methyl group or an ethyl group.

The alkyl group for R ⁴ and R ⁵ is preferably a C _1-4 alkyl group such as a methyl group or an ethyl group. Examples of the aralkyl group include a benzyl group and a phenethyl group. Further, examples of the aryl group include a phenyl group and a phenethyl group. Alkyl group, an aralkyl group or an ant - alkyl C _{1 to 4} such as methyl group, ethyl group, an alkoxyl group of C _{1 to 4} such as methoxy group, a halogen atom, a nitro group mentioned as the substituent of Le group To be R
It is preferable to use one having a benzyl group in either one or both of ⁴ and R ⁵ because it exhibits excellent low temperature curability and excellent coating film performance.

Examples of the halogen atom in the general formula (1) include fluorine, chlorine, bromine and the like, among which chlorine and fluorine are preferable.

In the general formula (1), X ⁻ is SbF ₆ ^−.
It is preferable to use these because they exhibit excellent low-temperature curability and coating film performance.

In the general formula (1), R ¹ is a hydroxyl group and R is
^{A combination in which 4} is a benzyl group and X ⁻ is SbF ₆ ^— is preferable.

Examples of the aromatic sulfonium salt represented by the general formula (1) include benzyl-4-hydroxyphenylmethylsulfonium hexafluoroantimonate.
, Benzyl-4-hydroxyphenylmethylsulfonium hexafluorophosphate, 4-acetoxyphenylbenzylmethylsulfonium hexafluoroantimonate, 4-acetoxyphenyldimethylsulfonium hexafluoroantimonate, benzyl-4-methoxyphenyl Methylsulfonium hexafluoroantimonate, benzyl-2-methyl-4-hydroxyphenylmethylsulfonium hexafluoroantimonate
, Benzyl-3-chloro-4-hydroxyphenylmethylsulfonium hexafluoroarsenate, benzyl-3-methyl-4-hydroxy-5-tert-butylphenylmethylsulfonium hexafluoroantimonate, 4-methoxybenzyl -4-hydroxyphenylmethylsulfonium hexafluorophosphate, dibenzyl-4-hydroxyphenylsulfonium hexafluoroantimonate, dibenzyl-4-hydroxyphenylsulfonium hexafluorophosphate, 4
-Acetoxyphenyldibenzylsulfonium hexafluoroantimonate, dibenzyl-4-methoxyphenylsulfonium hexafluoroantimonate, nitrobenzyl-4-hydroxyphenylmethylsulfonium hexafluoroantimonate, 3,5-dinitrobenzyl- 4-hydroxyphenylmethylsulfonium hexafluoroantimonate, β-naphthylmethyl-4
-Hydroxyphenylmethylsulfonium hexafluoroantimonate and the like.

Commercial products of the aromatic sulfonium salt represented by the general formula (1) include, for example, San-Aid SI.
-L85, same as left (Sun aid SI) -L110, same as left-
L145, Same as left-L150, Same as left-L160, Same as left-H
15, same left-H20, same left-H25, same left-H40, same left-H50, same left-60L, same left-80L, same left-10
0L (above, brand name by Sanshin Chemical Industry Co., Ltd.) and the like.

The compounding ratio of the aromatic sulfonium salt represented by the general formula (1) is about 0.1 to 5 parts by weight, preferably about 0.2 to about 100 parts by weight (solid content) of the epoxy group-containing resin. A range of 3 parts by weight is preferred. The mixing ratio is about 0.
If it is less than 1 part by weight, the curability is lowered and water resistance, corrosion resistance, weather resistance, workability, etc. are deteriorated, while if it exceeds about 5 parts by weight, the coating film appearance is deteriorated, which is not preferable.

The coating composition of the present invention comprises the above (A) to (C).
It can be suitably used as an organic solvent-based coating composition obtained by dissolving or dispersing the components in an organic solvent.

As the organic solvent used in the organic solvent-based coating composition, an organic solvent which can dissolve or disperse the components (A) to (C) and does not substantially react with these components can be used. Is an aromatic type such as toluene and xylene, an alcohol type such as ethanol, propanol and butanol, and an ethyl type such as ethyl cellosolve and butyl cellosolve.
Examples thereof include ter series, ketone series such as methyl isobutyl ketone, and ester series such as butyl acetate and cellosolve acetate. The solvent may be used alone or in combination of two or more.

In the coating composition of the present invention, in addition to the above-mentioned components, if necessary, a coloring agent, a filler, an ultraviolet stabilizer, an ultraviolet absorber, a fluidity adjusting agent, an anti-cissing agent, an anti-sagging agent, and a curing agent. Agents, paint storage stabilizers (eg, acetylacetone, diketone) and the like can be added.

The coating composition of the present invention can be applied to an article to be coated and cured by baking (for example, at a temperature of about 120 ° C. or higher) to form a coating film.

As the article to be coated, metals (iron, aluminum, etc.), inorganic materials (glass, etc.), plastics (polyester, etc.) and those obtained by subjecting these to surface treatment, undercoating, etc. can be used.

The coating can be carried out by a method known per se, for example, spray coating, brush coating, roller coating, flow coating and the like.

The coating film thickness is not particularly limited, but is about 10
A range of microns to 100 microns, preferably about 20 to 80 microns is suitable.

The curing conditions are, for example, about 100 to 180 ° C.
It can be cured at the temperature of about 20 to 40 minutes.

[0051]

The coating composition of the present invention comprises a curable composition having a hydroxyl group, an epoxy group and a reactive silicon group as a curing functional group in combination with a metal chelate as a catalyst and a specific cationic polymerization catalyst. , These catalysts are at low temperature (about 4
Does not work at 0 ℃, and also heats (about 100 ℃ or more)
Since it acts as a catalyst for the above-mentioned functional groups, it exhibits excellent effects such as excellent storage stability of the coating composition in one liquid and excellent properties such as low-temperature curing property, finish property, and anticorrosion property.

[0052]

EXAMPLES The present invention will be described in detail below with reference to examples.

Preparation Example of Acrylic Resin Solution A Methacryloxypropyltrimethoxysilane 150 g,
3.4-Epoxycyclohexylmethyl methacrylate 220 g, hydroxyethyl acrylate 232 g, cyclohexylmethyl acrylate 200 g, butyl methacrylate 198 g monomer and α, α′-azobisisobutyro Add a mixture of nitriles (polymerization initiators) to xylene 1
It was added dropwise to 000 g and radical polymerization reaction was carried out at 110 ° C. for 5 hours to produce an acrylic resin solution A having a solid content of 50% by weight. The resin has a number average molecular weight of about 10,000 and a hydroxyl value of 112 mg.
KOH / g, epoxy equivalent 909 g / mol (11 epoxy groups per molecule), alkoxysilane equivalent 526
g / mol (19 alkoxysilane groups per molecule)
Met.

Preparation Example of Acrylic Resin Solution B 3.4 Epoxycyclohexylmethyl methacrylate 400 g, hydroxyethyl acrylate 232 g, cyclohexylmethyl acrylate 184 g, butyl methacrylate 184 g of monomer and α , Α'-azobisisobutyronitrile (polymerization initiator) was mixed with xylene 1
It was added dropwise to 000 g and radical polymerization reaction was carried out at 110 ° C. for 5 hours to obtain an acrylic resin B solution having a solid content of 50% by weight. The resin has a number average molecular weight of about 10,000 and a hydroxyl value of 112 mgK.
OH / g and epoxy equivalent were 500 g / mol (20 epoxy groups per molecule).

Preparation Example of Acrylic Resin Solution C Methacryloxypropyltrimethoxysilane 243 g,
A mixture of 232 g of hydroxyethyl acrylate, 263 g of cyclohexylmethyl acrylate and 262 g of butyl methacrylate and α, α'-azobisisobutyronitrile (polymerization initiator) was added dropwise to 1000 g of xylene. Then, a radical polymerization reaction was carried out at 110 ° C. for 5 hours to produce an acrylic resin solution C having a solid content of 50% by weight. The resin has a number average molecular weight of about 10,000 and a hydroxyl value of 112 mgKOH /
g, alkoxysilane equivalent was 333 g / mol (30 alkoxysilane groups per molecule).

Production Example of Acrylic Resin Solution D 380 g of styrene, 23 of hydroxyethyl acrylate
A mixture of 2 g, 373 g of di-n-butyl maleate, 15 g of methacrylic acid and t-butyl peroxy-2-ethylhexanoate (polymerization initiator) was added to Swazol 1.
000 (aromatic petroleum naphtha, organic solvent) was added dropwise to 1000 g to carry out a radical polymerization reaction at 150 ° C. for 2 hours to produce an acrylic resin solution D having a solid content of 50% by weight. The resin has a weight average molecular weight of about 10,000 and a hydroxyl value of 112 mgKOH /
g.

Example 1 60 g of acrylic resin solution A, titanium white CR-95
(Ishihara Sangyo Co., Ltd., trade name, color pigment) 100 g,
A mixture of 20 g of xylene and 2 g of acetylacetone was dispersed in a shaker to prepare a titanium white pigment paste. Then, 140 g of acrylic resin solution A, 5 g of acetylacetone, 5 g of tris (ethylacetoacetate) aluminum solution having a solid content of 10% by weight, and 50 g of solid content of 50% by weight benzyl-4-hydroxyphenylmethylsulfonium hexafluoroantimonate were added to this product. The coating material of Example 1 was manufactured by adding 0.4 g.

Examples 2 and 3 The paints of Examples 2 and 3 were produced in the same manner as in Example 1 with the formulations shown in Table 1. Comparative Examples 1 to 3 Comparative Examples 1 to 3 with the formulations shown in Table 1 in the same manner as in Example 1.
Was manufactured.

[0059]

[Table 1]

In Table 1, epoxy compounds are Celoxide 2021 (trade name, alicyclic epoxy resin, manufactured by Daicel Chemical Co., Ltd.), and silyl group-containing resins are low condensation products of tetraethyl silicate (average degree of condensation about 6). The reaction product of ε-caprolactam and the aluminum chelate solution has a solid content of 1
0 wt% tris (ethylacetoacetate) aluminum solution, Suzukilate solution has a solid content of 50 wt% monobutyltin tris (acetylacetonate), and cationic polymerization catalyst solution has a solid content of 50 wt% benzyl-4-hydroxyphenylmethyl. Sulfonium hexafluoroantimony
Represents

Performance tests were carried out using the paints of Examples and Comparative Examples obtained above. Table 1 shows the results.

In Table 1, the storage stability of the coating composition was determined by the following method.

The samples of the examples and comparative examples were diluted with a Stormer viscometer to a viscosity of 70 KU and used as samples. After storing the sample in a sealed state at 40 ° C. for 2 weeks, the viscosity of the sample was measured and evaluated according to the following criteria. ○
Indicates a viscosity increase of 0-10 KU, △ indicates a viscosity increase of 11
.About.19 KU, x indicates gelation from 20 KU or more.

Further, in Table 1, the coating film performance test was conducted by the following method.

Preparation of coated plate: Zinc phosphate treated to a thickness of 0.
An 8 mm steel plate was spray-coated to a dry film thickness of about 40 microns and baked at 140 ° C for 30 minutes, which was used as a test.

Specular reflectance: 60 of JIS K-5400
The degree of specular gloss was measured.

Curability: The appearance of the coating film was visually evaluated after wiping the surface of the coating film with xylene impregnated ten times with a fingertip. ○ indicates that the surface has no abnormality and has good curability.
Indicates that the surface is slightly scratched and the curability is inferior, and x indicates that the surface is dissolved and the curability is remarkably inferior.

Pencil hardness: An evaluation was made by a scratch according to JIS K-5400.

Corrosion resistance: A cross cut reaching the base steel plate was put in the coating film using an NT cutter, an anticorrosion paint was applied to the edge part and the back surface, and a spray test with 5% by weight of saline solution (JIS-K-5400). I went. After testing for 240 hours, a peeling test of the cross-cut portion was performed with cellophane tape. ◎: peel width less than 1 mm from cross cut, ○: peel width from cross cut 1 to 3 mm, △: peel width from cross cut 3.1 to 5 mm, ×: cross cut The peeling width from the sheet exceeds 5 mm.

Claims (2)

[Claims] 1. The following component (A) contains a reactive silicon group, a hydroxyl group and an epoxy group as essential functional group components, and these functional groups contain the same resin or different resins contained in the molecule. Mixture 100 parts by weight (B) Metal chelate catalyst 0.1 to 5 parts by weight (C) General formula (1) (Where R¹Is a hydrogen atom, a hydroxyl group, an alkoxyl group orAnd Y represents an optionally substituted alkyl group, alkoxyl group, phenyl group or phenoxy group, and R^TwoAnd R^ThreeEach represents a hydrogen atom, a halogen atom or an alkyl group, and R^FourAnd R^FiveRepresents an optionally substituted alkyl group, aralkyl group or aryl group, and X^-Is SbF₆ ^-, PF₆ ^-, AsF₆ ^-Or BF_Four ^- A curable coating composition comprising 0.1 to 5 parts by weight of a cationic polymerization catalyst of an aromatic sulfonium salt represented by 2. The curable coating composition according to claim 1, wherein X ^{− of the} aromatic sulfonium salt represented by the general formula (1) is SbF ₆ ⁻ .