JPS62290766A - Coating composition - Google Patents

Abstract

PURPOSE:To improve curability, storage stability, film performance, etc., by blending a coating compsn. mainly composed of a specified polymer contg. an alkoxyacrylsilane with a zirconium chelate compd. as a crosslinking curing agent. CONSTITUTION:A compd. of the formula (wherein R<1> is H or methyl; R<2> is a 1-5C hydrocarbon; R<3> is a 1-10C hydrocarbon; and R<4> is OR<3> or a 1-6C hydrocarbon) (e.g., acryloxyethyltrimethoxysilane) alone is polymerized or copolymerized with other polymerizable monomer (e.g., methyl acrylate) to produce a polymer composed of at least 3wt% compd. of the formula. The polymer is blended with a zirconium chelate compd. [e.g., zirconiumtetra(acetylacetonato)] as a crosslinking curing agent and optionally, an org. solvent, a color pigment, etc. to obtain the desired coating compsn.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a coating composition, and more particularly, the present invention relates to a coating composition having the general formula % (R1 is hydrogen or a methyl group, R2 is a hydrocarbon group having 1 to 5 carbon atoms, and R3 is a hydrocarbon group having 1 to 5 carbon atoms. ~10 hydrocarbon groups, R4 is OR1 and/or a hydrocarbon group having 1 to 6 carbon atoms) (hereinafter sometimes abbreviated as "alkoxyacrylic silane"). below,
The present invention relates to a coating composition that has improved properties such as curability and adhesion of an "alkoxysilane-containing polymer" (sometimes abbreviated as "alkoxysilane-containing polymer").

Paints using the above-mentioned alkoxysilane-containing polymers are already known, and the paints are applied and a coating film is formed by a curing reaction. The curing reaction mechanism is that the alkoxy groups based on the alkoxyacrylic silane in the alkoxysilane-containing polymer are hydrolyzed by moisture in the air, and the silanol groups generated thereby condense to form siloxane bonds and cure. has been done. However,
The rate of hydrolysis mentioned above is extremely slow in the absence of a catalyst, so
To promote it, acid catalysts (e.g. hydrochloric acid, p-toluenesulfonic acid, etc.), basic catalysts (e.g. dimethylamine ethanol, etc.), organotin compounds (e.g. dibutyltin dilaurate, etc.) or metal alkoxides (e.g. titanium, zirconium, Compounds such as alkoxides of aluminum, etc., as well as aluminum chelate compounds are blended. However, even when such compounds are used, curability, storage stability, coating film performance, etc. are insufficient, and improvements in these properties are strongly desired.

That is, with acid catalysts and basic catalysts, the curability of the coating film is insufficient, and the chemical resistance and water resistance of the coating film formed are also poor. Organotin compounds have good curing properties but very poor adhesion, and when metal alkoxides are used, the curing reaction rate of alkoxysilane-containing polymers is too fast, resulting in poor storage stability. The time from when it is applied to when it is used (painted) (
The pot life (pot life) is too short, making it difficult to control painting operations. Another disadvantage is that the cured coating film has poor adhesion because it cures too quickly. Aluminum chelate compounds are available to improve these drawbacks, but although they improve storage stability, they have problems of poor chemical resistance, adhesion, and weather resistance.

In view of this situation, the inventors of the present invention have conducted intensive research to further improve the curability, storage stability, coating performance, etc. of alkoxysilane-containing polymers. It was discovered that the various deficiencies described above can be overcome by using a chelate compound, and the present invention was completed.

That is, the present invention provides a compound represented by the following general formula 3
As a crosslinking reaction curing agent to the polymer containing % by weight or more,
A curable composition comprising a zirconium chelate compound (where R1 is hydrogen or a methyl group, R2 is a hydrocarbon group having 1 to 5 carbon atoms, and R3 is a hydrocarbon group having 1 to 5 carbon atoms).
~10 hydrocarbon groups, R4 is OR3 and (also) a C1-6 hydrocarbon group. ) regarding.

First, the alkoxysilane-containing polymer in the present invention is
It is a polymer of alkoxyacrylic silane represented by the above general formula or a copolymer with other heptamers. In the alkoxyacrylic silane represented by the above general formula,
](2 (hydrocarbon group having 1 to 5 carbon atoms) is, for example, a methylene group, an ethylene group, a propylene group, 1, 2-.

1.3-, 2.3-butylene group, tetramethylene group,
-OR" (R3 is a hydrocarbon group having 1 to 10 carbon atoms) includes 1 such as a methoxy group,
Ethoxy, propoxy, butoxy, pentoxy and the like are suitable. In addition, R4 is partially or entirely the same as -0R3, or has 1 to 6 carbon atoms.
is a hydrocarbon group. Specifically, for example, acryloxyethyltrimethoxysilane, methacryloxyethyltributoxysilane, acryloxydipropyltrimethoxysilane, methacryloxypropyltrimethoxysilane,
Examples include methacryloxypropyltri-n-butoxysilane, acryloxytetramethylenetributoxysilane, methacryloxypropyltrimethoxysilane, and among these, acryloxypropyltrimethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropyl Tri-n-butoxysilane is preferred.

The alkoxysilane-containing polymer in the present invention is a copolymer of one or more polymers selected from the above-mentioned alkoxyacrylic silanes, or one or more selected from the alkoxyacrylic silanes and another polymerizable monomer. It is a polymer that has been made to last. Other polymerizable polymers include, for example, alkyl acrylates (having 1 carbon number ~20) Ester, methyl methacrylate, ethyl methacrylate, propyl methacrylate, butyl methacrylate, 2-methacrylate
Alkyl methacrylates such as ethylhexyl, tridecyl methacrylate, lauryl methacrylate (1 to 1 carbon atoms)
20) Hydroxyl group-containing polymerizable monomers such as esters, hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate, and hydroxypropyl methacrylate; glycidyl group-containing polymerizable monomers such as glycidyl acrylate and glycidyl methacrylate; acrylamide, methacrylamide, propyl acrylamide, butyl Examples include, but are not limited to, amide polymerizable monomers such as acrylamide, diacrylamide, and N-methylolacrylamide, styrene, styrene derivatives, vinyl acetate, vinyl isobutyl ether, acrylonitrile, and divinylbenzene. .

In the present invention, compared to a polymer containing alkoxysilane, compared to a polymer consisting only of alkoxyacrylic silane,
Copolymerizable monomers with other polymerizable monomers are superior in terms of the physical performance of the formed coating film, and the ratio of the two to be copolymerized is not particularly limited, but based on the total weight of the alkoxy acrylic Silane 3% or more, especially 10 to 30%, other polymerizable monomers 97% or less, especially 9
These polymer ranges are preferred, with a range of 0-70% being preferred.

Next, the zirconium chelate compound used in the present invention is a compound formed by coordinating a ligand (chelating agent) having two coordinate sites with oxygen as a coordinating atom to zirconium. The ligand can be used at room temperature (80°C
(below) is preferable, and specific examples include diketones and ketoesters such as methyl acetoacetate, 1m-ethyl acetate, acetylacetone, dimethyl malonate, and diethyl malonate. It is particularly preferred to use a ligand in which 8-coordinated ligands are used, especially on tetravalent zirconium.

The above-mentioned alkoxysilane-containing polymer and zirconium chelate compound are uniformly compatible with each other in a fairly wide range of proportions, but in the present invention, the blending ratio of the zirconium chelate compound is determined based on the solid content ratio of 100% of the alkoxysilane-containing polymer. A range of 0.1 to 20 parts by weight, preferably 0.3 to 10 parts by weight per part by weight is suitable. 0
．． If it is less than 1 part by weight, the curability of the coating film will be insufficient, and if it is more than 20 parts by weight, unreacted zirconium chelate compounds may remain in the coating 11, reducing the gel fraction (curability). .

Each zirconium chelate compound is used alone, but two or more zirconium chelate compounds with different chelating agents may be used in combination.

It is also possible to use a mixture of the zirconium chelate compound and commonly used acid catalysts, basic catalysts, iftin compounds, and aluminum chelate compounds.

The composition of the present invention can be obtained by mixing both of the components described in (-) at the time of use. A stopper, an additive, etc. can also be added as necessary.

In addition, the zirconium chelate compound can be diluted in advance with the thinner used during painting and added. 6 The performance of the coating film formed by applying this composition is 1. It is significantly superior to those containing tin compounds and aluminum chelate compounds, cures in a short time through crosslinking reaction, and exhibits excellent adhesion, water resistance, chemical resistance, and weather resistance.

Although the crosslinking reaction and curing mechanism of the coating film formed by applying the composition of the present invention has not been fully elucidated, first, the alkoxysilane based on the alkoxyacrylic silane in the alkoxysilane-containing polymer reacts with moisture in the air. (hydrolysis) to release silanol groups. At this time, the zirconium chelate compound is considered to act as a catalyst to promote this hydrolysis reaction. Next, it is presumed that the silanol group and the zirconium chelate compound react to form a -S i -0-Z r-0-5i- bond, and the alkoxysilane-containing polymer is crosslinked and cured. Although this curing reaction is a reversible reaction, the curing reaction proceeds rapidly as the chelating agent of the zirconium chelate compound produced as a by-product is volatilized from the coating film.

Therefore, it is preferable to use a chelating agent for the zirconium chelate compound that volatilizes at room temperature (80'C or less). Further, the composition of the present invention is preferably used as a paint that dries mainly at room temperature (80'O or less), and the humidity in the air at that time is about 30% or more in order to carry out the curing reaction quickly. This is desirable.

Even when the humidity is 30% or less, by copolymerizing a hydroxyl group-containing monomer with an alkoxysilane-containing polymer, the zirconium chelate compound reacts with the hydroxyl group and can be crosslinked and cured without being significantly affected by humidity. .

Next, the present invention will be explained based on examples. Parts and % in Examples and Comparative Examples represent parts by weight and % by weight.

Example 1 20 parts of acryloxypropyltrimethoxysilane, 20 parts of styrene, 40 parts of n-butyl methacrylate, and n-
A copolymer obtained by copolymerizing a monomer component consisting of 20 parts of butyl acrylate (LA average molecular weight approximately 20,000
) to 200 parts of a 50% solids solution dissolved in toluene,
Two parts of zirconium tetra (acetylacetonate) were blended and mixed uniformly to obtain a coating composition.

Example 2 10 parts of acryloxypropyltrimethoxysilane and 10 parts of methacrylate, 30 parts of methyl methacrylate, n-
Zirconium tetra(
5 parts of acetylacetonate) were added and mixed uniformly to obtain a coating composition.

Example 3 A coating composition was obtained in the same manner as in Example 2, except that 30 parts of n-butyl methacrylate in the acrylic monomer composition was replaced with 20 parts of n-butyl methacrylate and 10 parts of hydroxyethyl methacrylate.

Example 4 15 parts of methacryloxypropyltrimethoxysilane, 15 parts of styrene, 20 parts of methyl methacrylate, 20 parts of n-butyl methacrylate.

Zirconium tetra is added to 200 parts of a 50% solids solution prepared by dissolving a copolymer (number average molecular weight approximately 20.000) in toluene, which is obtained by copolymerizing monomer components consisting of 20 parts of n-butyl acrylate and 10 parts of hydroxyethyl methacrylate. 100 parts of (acetylacetonate) were placed and mixed uniformly to obtain a coating composition.

Comparative Example 1 The same procedure as in Example 1 was carried out except that 2 parts of zirconium tetra(acetylacetonate) in Example 1 was replaced with 2 parts of dibutyltin dilaurate.

Comparative Example 2 The same procedure as in Example 4 was carried out except that 10 parts of zirconium tetra(acetylacetonate) in Example 4 was replaced with 10 parts of aluminum tris(acetylacetonate).

Comparative Example 3 The same procedure as in Example 4 was carried out except that 10 parts of zirconium tetra(acetylacetonate) in Example 4 was replaced with 5 parts of dimethylamine ethanol.

Comparative Example 4 The same procedure as in Example 4 was carried out except that 10 parts of zirconium tetra(acetylacetonate) in Example 4 was replaced with 5 parts of para-toluenesulfonic acid.

Performance Test Results Table 1 shows the results of testing the performance of coating films formed by coating the compositions obtained in Examples and Comparative Examples.

Claims (1)

[Scope of Claims] A coating composition comprising a polymer containing 3% by weight or more of a compound represented by the following general formula, and a zirconium chelate compound as a crosslinking reaction curing agent. ▲There are mathematical formulas, chemical formulas, tables, etc.▼ (Here, R^1 is hydrogen or a methyl group, R^2 is a hydrocarbon group with 1 to 5 carbon atoms, and R^3 is a hydrocarbon group with 1 to 10 carbon atoms. , R^4 is OR^3 and/or carbon number 1~
6 hydrocarbon group. )