JPH09169846A - Curable composition and coating agent - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a curable compsn. improved in hardness, clarity, adhesive properties, resistances to chemicals and solvents, storage stability of the soln., and softness by compounding an alkoxysilane, a silane coupling agent, water, an org. solvent, and a catalyst and specifying the water content. SOLUTION: This curable compsn. is prepd. by compounding a tetraalkoxysilane represented by the formula: R<2> n Si(OR<1> )4-n (wherein R<1> and R<2> are each a 1-20C alkyl; and (n) is 1-3)(e.g. tetramethoxysilane) and/or its oligomer formed by its hydrolysis and condensation (A), an epoxidized silane coupling agent such as represented by formula I or II (wherein R is methyl or ethyl)(B) in a wt. ratio to component A of (10:1)-(1:10), at least one org. solvent (C) selected from among an alcohol, a glycol, a hydrocarbon, an ester, a ketone, an ether, etc., (C) in a wt. ratio to component A of 0.5-10, a catalyst (e.g. an inorg. or org. acid or an alkali catalyst), water in an amt. theoretically capable of hydrolyzing and condensing 40-75% of component A, and, if necessary, an acrylic resin.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a curable composition and a coating agent using the same, and more specifically,
High hardness, transparency, adhesion, chemical resistance, applied to the surface of glass, iron, stainless steel, aluminum and other metals, plastic, wood, cement and other products
It provides a coating agent having excellent solvent resistance.
Heretofore, as a liquid composition for coating intended to improve the above properties, for example, International Application No. PCT / JP
There is a liquid composition obtained by hydrolyzing an alkoxysilane by a specific method described in U.S. Pat. No. 94/02169. However, these conventional coating compositions are inferior in film properties obtained over a long period of time from the preparation of the solution, and when the film thickness of the obtained coating film is small and the film thickness is increased due to insufficient flexibility. There are drawbacks such as cracks.

[0002]

In view of the above circumstances, the present invention provides a coating agent having excellent hardness, transparency, adhesion, chemical resistance, solvent resistance, storage stability of a solution, and flexibility. It is intended to provide a composition for use.

[0003]

Means for Solving the Problems The present inventors have made intensive studies to solve the above-mentioned problems, and as a result, have reached the present invention. That is, the present invention is a curable composition obtained by blending an alkoxysilane, a silane coupling agent having an epoxy group, a theoretical amount of 40 to 75% hydrolyzable and condensable water, an organic solvent and a catalyst. Exist in.

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.
As the alkoxysilane used in the present invention, usually,
_{^{R 2 n Si (OR 1)}} 4-n (R 1, R 2 is an alkyl group of C1-20, n = 1 to 3 integer) alkoxysilane represented by, for example, tetramethoxysilane, tetraethoxysilane, tetra Tetraalkoxysilanes such as propoxysilanes and / or oligomers that are partially hydrolyzed condensates thereof are used. The silane coupling agent having an epoxy group used in the present invention is not particularly limited, for example,

[0005]

Embedded image (Wherein, R represents —CH ₃ or —C ₂ H ₅ ).

The silane coupling agent is preferably used in a weight ratio of about 10: 1 to 1:10 with respect to the alkoxysilane. As the organic solvent used in the present invention, one or more of alcohols, glycols, hydrocarbons, esters, ketones, ethers and the like are used. Specific examples of alcohols include methanol, ethanol, isopropyl alcohol, n-butanol, isobutanol, and octanol.
Examples of the glycols include glycols such as ethylene glycol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono n-propyl ether, ethylene glycol mono n-butyl ether and derivatives thereof.

As hydrocarbons, benzene, kerosene,
Toluene, xylene and the like, and as the esters,
Examples include methyl acetate, ethyl acetate, butyl acetate, methyl acetoacetate, and ethyl acetoacetate. Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, and acetylacetone. Examples of ethers include ethyl ether, butyl ether, methyl cellosolve, ethyl cellosolve, dioxane, furan, and tetrahydrofuran. The addition method of these organic solvents is not particularly limited, the type of formulation,
Depending on the compatibility, etc., it is appropriately selected, but in the present invention, in order to obtain a compounding liquid having a better compatibility with the acrylic resin,
It is preferable to newly add a solvent or distill it off.

The amount of the organic solvent used is preferably 50 to 1000 parts by weight, more preferably 50 to 500 parts by weight, based on 100 parts by weight of the alkoxysilane. When the amount of the organic solvent used is less than 50 parts by weight, the composition has reduced storage stability and is easily gelled. If the amount exceeds 1,000 parts by weight, the coating film thickness of the obtained coating film becomes extremely thin.

Examples of the catalyst used in the present invention include inorganic acids such as hydrochloric acid, acetic acid, nitric acid, formic acid, sulfuric acid and phosphoric acid, formic acid, acetic acid, propionic acid, paratoluenesulfonic acid, benzoic acid, phthalic acid and maleic acid. Organic acids such as acids, potassium hydroxide, sodium hydroxide, calcium hydroxide,
Alkaline catalysts such as ammonia, organic metals, metal alkoxides, organic tin compounds such as dibutyltin dilaurate, dibutyltin dioctate, dibutyltin diacetate, aluminum tris (acetylacetonate),
Titanium tetrakis (acetylacetonate), titanium bis (butoxy) bis (acetylacetonate), titanium bis (isopropoxy) bis (acetylacetonate), zirconium tetrakis (acetylacetonate), zirconium bis (butoxy) bis (acetylacetate) Metal chelates such as zirconium bis (isopropoxy) bis (acetylacetonate), and boron compounds such as boron butoxide and boric acid.

The content of the catalyst is 0. 0, based on the total amount of the epoxy groups of the silane coupling agent having an epoxy group.
05-2 mol% is suitable. When the catalyst content is 0.0
When the amount is less than 5 mol%, the condensation reaction is generally slow and the film is not sufficiently cured. When the amount exceeds 2 mol%, the residual epoxy group decreases with time, and the stability of the composition becomes poor. For this reason, there is a possibility that the physical properties of the coating film such as hardness when combined with the acrylic resin become insufficient. In the present invention, an amount of water that can theoretically hydrolyze and condense the alkoxysilane by 40 to 75% is added. When the amount of water is less than 40%, the condensation is insufficient and the physical properties of the coating such as hardness are not sufficient. If it exceeds 75%, the storage stability of the solution is reduced, and the solution is apt to gel.

Here, the amount of water is represented by the ratio to the amount of water that can theoretically hydrolyze and condense the alkoxysilane by 100%, that is, the ratio of water to half the number of moles of the alkoxy group of the alkoxysilane. It is. A curable composition is prepared by mixing these components, but as a preferred embodiment, a predetermined amount of water is added to the alkoxysilane in advance to advance the hydrolysis condensation to a desired degree, and then the silane coupling agent is added. Added. This is because in this case, the obtained coating film has higher hardness. The catalyst and the solvent are usually present at the time of performing the hydrolysis-condensation reaction.

The liquid curable composition thus obtained may be used as it is, but preferably, further, oxygen, sulfur or oxygen is added to the carbon atom at the 1-position or 2-position of the carboxyl group, its anhydride group or the alkoxyl group. By blending an acrylic resin having at least one functional group of an alkoxycarbonyl group or an amino group to which a nitrogen atom is bonded, a coating agent with more excellent properties can be obtained. As the acrylic resin, specifically, (a) an ester obtained from (meth) acrylic acid and an alkanol having 1 to 18 carbon atoms, and (b) a carboxyl group, an anhydride group thereof,
An α, β-ethylenically unsaturated hydrocarbon having at least one functional group of an alkoxycarbonyl group having an oxygen, sulfur, or nitrogen atom bonded to the carbon atom at the 1-position or 2-position of the alkoxyl group, or an amino group, An acrylic copolymer containing as an essential component is preferably used.

Examples of the ester (a) include methyl (meth) acrylate, ethyl (meth) acrylate,
N-butyl (meth) acrylate, isobutyl (meth) acrylate, 2-ethylhexyl (meth) acrylate,
Decyl (meth) acrylate, dodecyl (meth) acrylate and the like can be mentioned. Examples of the α, β-ethylenically unsaturated hydrocarbon of (b) include (meth) acrylic acid, maleic acid, fumaric acid, itaconic acid, methylenemalonic acid,
Aconitic acid, citraconic acid, 4-carboxystyrene, maleic anhydride, itaconic anhydride, citraconic anhydride, dodecenylsuccinic anhydride, allylamine, allylaniline, N- (meth) acryloylamine, N-phenyl-N-methacryloylamine, amino Styrene, aminomethylstyrene, diallylamine, vinylimidazole, diethylaminoethyl (meth) acrylate, 1-methoxymethyl (meth) acrylate, phthalimidomethyl (meth) acrylate, β-p-toluenesulfonic acid (meth) acrylate, Examples include β-p-nitrophenylthioethyl (meth) acrylate and β-p-methylthioethyl (meth) acrylate.

The amount of the acrylic resin compounded is usually a weight ratio to the alkoxysilane and the silane coupling agent,
(Alkoxysilane + silane coupling agent): Acrylic resin = 5: 95 to 85:15. The coating agent obtained in the present invention has little change with time of the solution, is excellent in storage stability, has high hardness, transparency, adhesion, chemical resistance,
It is possible to provide a coating film having excellent solvent resistance and flexibility.

[0015]

The present invention will be described in more detail with reference to the following examples. The evaluation in the examples was performed by the following method. (1) Quantification of epoxy group: It was performed by tetraethylammonium bromide-perchloric acid titration. That is, 20
An excess amount of a tetraethylammonium bromide acetic acid solution was added to the epoxy group, and titration was performed with a 0.1N perchloric acid acetic acid solution using crystal violet as an indicator. (2) Acid resistance: One drop of a 5% aqueous solution of sulfuric acid was dropped on the film, left for 24 hours, washed with water and visually checked for changes in the film. (3) Solvent resistance: Xylene was impregnated into absorbent cotton, the membrane surface was wiped 100 times, and the elution of the membrane was visually confirmed.

Example 1 Using a 500 ml four-necked flask equipped with a reflux condenser and a stirrer, to commercially available tetramethoxysilane (76 g),
After adding 63.2 g of methanol and stirring, 1N hydrochloric acid 1
g and 9.8 g of water (60% to the amount of theoretically complete hydrolytic condensation of tetramethoxysilane) were added, and the mixture was refluxed.
A hydrolysis-condensation reaction was carried out at an internal temperature of 65 ° C. for 3.5 hours.
Next, the following silane coupling agent having an epoxy group (manufactured by Nippon Yunika, product number A-187)

[0017]

Embedded image 19.0 g was added and left at room temperature for 1 day to obtain a curable composition. (The catalyst amount is 0.13 mol% with respect to the total amount of epoxy groups in the silane coupling agent.) As a result of quantitative determination of epoxy groups, 100% of the epoxy groups remain after standing for 10 days at room temperature. No change with time was observed in the solution, and this composition retained a transparent liquid state even after standing at 50 ° C. for 13 days, showing good stability with time.

Example 2 Using a 500 ml four-necked flask equipped with a reflux condenser and a stirrer, to commercially available tetramethoxysilane (76 g),
After adding 63.2 g of methanol and stirring, 1N hydrochloric acid 1
g and 9.8 g of water were added, and a hydrolysis-condensation reaction was performed at an internal temperature of 65 ° C. for 3.5 hours. Next, 101.6 g of methyl isobutyl ketone was added, and then 101.6 g of the solvent was distilled off at a top temperature of 65 to 66 ° C. to replace methanol with methyl isobutyl ketone. 19.0 g of the silane coupling agent used in Example 1 was added and left at room temperature for 1 day to obtain a curable composition. As a result of quantitative determination of epoxy group, 10 at room temperature
Even after standing for a day, 100% of the epoxy groups remained. Also,
This composition remained a transparent liquid even after standing at 50 ° C. for 13 days.

Example 3 Using a 500 ml four-necked flask equipped with a reflux condenser and a stirrer, to commercially available tetramethoxysilane (76 g),
After adding 63.2 g of methanol and stirring, 1N hydrochloric acid 1
g and 9.8 g of water were added, and a hydrolysis-condensation reaction was performed at an internal temperature of 65 ° C. for 3.5 hours. Then, 19.0 g of the silane coupling agent used in Example 1 and 46.25 of methanol were used.
g, aluminum tris (acetylacetonate) 0.
67 g and 1.30 g of water were added and left at room temperature for 1 day to obtain a curable composition. (The amount of the catalyst is 2.6 mol% with respect to the total amount of the epoxy groups of the silane coupling agent.) As a result of the quantification of the epoxy groups, the residual rate of the epoxy groups is 85% after 4 days of standing at room temperature and 68 after 10 days. %Met. This composition remained a transparent liquid even after standing at 50 ° C. for 14 days.

Comparative Example 1 A composition was prepared in the same manner as in Example 1 except that the amount of water was changed to 13.4 g (80% based on the theoretical complete hydrolytic condensation amount of tetramethoxysilane). . This composition gelled after standing at room temperature for 5 days. Comparative Example 2 Tetramethoxysilane oligomer (manufactured by Mitsubishi Chemical Corporation,
Product name "MKC silicate MS51", 40% hydrolyzed condensate of tetramethoxysilane) 19.2 g, 26.5 g of methanol, 0.33 g of 0.1N hydrochloric acid, 3.74 g of water
(113% relative to the amount of tetramethoxysilane oligomer theoretically completely hydrolyzed and condensed) was added, and the mixture was allowed to stand at room temperature for 1 day, and then the silane coupling agent 6.33 used in Example 1 was added.
g was added to prepare a composition. This composition is 50 ° C, 1
Gelled in days.

Comparative Example 3 Tetramethoxysilane oligomer (manufactured by Mitsubishi Chemical Corporation,
Product name "MKC silicate MS51", 40% hydrolyzed and condensed product of tetramethoxysilane), 26.5 g of methanol, 0.192 g of aluminum tris (acetylacetonate), 4.07 g of water (theoretical theory of tetramethoxysilane oligomer) A composition was prepared by adding 6.33 g of a silane coupling agent (manufactured by Nippon Yunika Co., Ltd., product number A-187) after adding 1% to the amount completely hydrolyzed and condensed above. As a result of quantifying the epoxy group, the residual rate of the epoxy group was 70% after 1 day and 50% after 2 days.

Comparative Example 4 A composition was prepared in the same manner as in Comparative Example 3 except that 0.192 g of maleic acid was used instead of aluminum tris (acetylacetonate). As a result of quantifying the epoxy group, the residual rate of the epoxy group was 40% after 1 day of standing at room temperature. Comparative Example 5 Tetramethoxysilane oligomer (manufactured by Mitsubishi Chemical Corporation,
A composition is prepared by adding 26.5 g of methanol, 0.192 g of aluminum tris (acetylacetonate) and 4.07 g of water to 19.2 g of "MKC silicate MS51", a 40% hydrolyzed condensate of tetramethoxysilane. did. This composition gelled after standing at 50 ° C. for 11 days.

Example 4 Using a 500 ml four-necked flask equipped with a reflux condenser and a stirrer, 70 g of isopropyl alcohol, 70 g of methyl ethyl ketone, 24 g of methyl methacrylate, 27 g of ethyl acrylate, 6 g of methacrylic acid, 2 acrylic acid
3 g of -hydroxyethyl and 2 g of 2,2'-azobisisobutyronitrile were added, and the mixture was stirred at 65 ° C for 6 hours,
An acrylic resin solution was obtained. This acrylic resin solution 14.
35 g and 2.85 g of methyl isobutyl ketone were added to 10 g of the curable composition obtained in Example 2 to obtain a coating liquid. The non-volatile component in the coating liquid when the alkoxysilane was completely hydrolyzed and condensed was calculated to be 25%.

A glass plate (70 mm
× 150 mm × 2 mm) using a 500 μm applicator and dried at 150 ° C. for 2 hours.
A transparent coating film without cracks or peeling was obtained, and the average film thickness of the coating film was 25 μm. The result of the pencil hardness test was 2 to 3H, and the acid resistance and solvent resistance were good. The acrylic resin component in the film when the alkoxysilane was completely hydrolyzed and condensed was 63%.

Comparative Example 6 11.18 g of the acrylic resin solution obtained in Example 4 was added to 10 g of the composition obtained in Comparative Example 5, and coating was carried out in the same manner as in Example 4. The non-volatile component in the liquid was 25%, and the acrylic resin component in the film was 63% (calculated values in all cases). Fine cracks were visually confirmed in the obtained coating film (average film thickness 25 μm).

[0026]

According to the present invention, a liquid curable composition having excellent storage stability is obtained.

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Jie Toriumi 1000 Kamoshida-cho, Aoba-ku, Yokohama-shi, Kanagawa Mitsubishi Chemical Corporation Yokohama Research Institute

Claims (4)

[Claims] 1. A composition comprising an alkoxysilane, a silane coupling agent having an epoxy group, water, an organic solvent and a catalyst, and the water content of the alkoxysilane is theoretically 40 to 75%. A curable composition, characterized in that it is a hydrolyzable and condensable amount. 2. The content of the catalyst is 0.05 to 2 mol% with respect to the total amount of epoxy groups contained in the silane coupling agent having epoxy groups.
The curable composition according to the above. 3. The curable composition according to claim 1, wherein water is added to the alkoxysilane in advance to hydrolyze and condense it, and then a silane coupling agent having an epoxy group is added. 4. A functional group of at least one of a carboxyl group, an anhydride group thereof, an alkoxycarbonyl group having an oxygen, sulfur or nitrogen atom bonded to the carbon atom at the 1-position or 2-position of an alkoxyl group, and an amino group. A coating agent obtained by incorporating the acrylic resin having the curable composition according to any one of claims 1 to 3.