JP3247369B2 - Coating composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Industrial applications]

The present invention relates to a coating composition for low-temperature curing.

[0002]

[Prior art]

Synthetic resins containing an oxirane ring, such as epoxy resins and polymers containing a vinyl monomer having a glycidyl ether group, are subject to acid-catalyzed or base-catalyzed cleavage of the oxirane ring with a nucleophile or electrophile. It has been used for various applications focusing on low-temperature curability based on it. Conventionally, phthalic anhydride, maleic anhydride, p-toluenesulfonic acid, tris (dimethylaminomethyl) phenol, polyamine, polyamide, benzyldimethylamine, boron fluoride, etherate, sodium alkoxide and the like have been used as the acid catalyst and the base catalyst. ing.

[0003]

However, with the above-mentioned conventional catalyst, the low-temperature curability of the synthetic resin containing the oxirane ring is not sufficient, and there remains a problem in various physical properties such as weather resistance and chemical resistance. ing.

[0004]

[Means for Solving the Problems]

The present invention provides, as a means for solving the above-mentioned conventional problems, one or more kinds of vinyl monomers having an oxirane ring and other vinyl monomers copolymerizable with the vinyl monomer having an oxirane ring. A copolymer of one or two or more kinds of monomers, and a polymer A containing 5 to 20 parts by weight of a vinyl monomer having an oxirane ring in 100 parts by weight of the copolymer, and pKa3 99: 1 to 50:50 with the following carboxylic acid B
An object of the present invention is to provide a coating composition comprising 5 to 50 parts by weight of a compound C having a hydrolyzable silyl group per 100 parts by weight of a mixture in a weight ratio. Hereinafter, the present invention will be described in more detail.

[Vinyl monomer having an oxirane ring] Examples of the vinyl monomer having an oxirane ring used in the present invention include vinyl having a glycidyl group such as glycidyl acrylate, glycidyl methacrylate and allyl glycidyl ether. Monomer or the following structural formula

Embedded image Wherein R is H or CH ₃ . And a vinyl monomer having an alicyclic oxirane ring.

[Polymer A] The polymer A of the present invention is generally one or more of the above-mentioned vinyl monomers having an oxirane ring, or one of the above-mentioned vinyl monomers having an oxirane ring. Or a mixture of two or more and one or two or more other vinyl monomers copolymerizable with the vinyl monomer, methanol, ethanol, isopropanol, n-butanol,
Ethyl acetate, n-butyl acetate, toluene, xylene, acetone, methyl ethyl ketone, in a solvent mixture of one or more organic solvents such as methyl isobutyl ketone,
It can be obtained by polymerization using an oil-soluble polymerization initiator such as benzoyl peroxide, lauroyl peroxide, cumene hydroperoxide, and azobisisobutyronitrile. Other vinyl monomers copolymerizable with the vinyl monomer having an oxirane ring include, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl propyl acrylate, n-butyl acrylate, iso- Butyl acrylate, 2-ethylhexyl acrylate, cyclohexyl acrylate, tetrahydrofurfuryl acrylate, methyl methacrylate, ethyl methacrylate, n-butyl methacrylate, iso-butyl methacrylate, 2-ethylhexyl methacrylate, stearyl methacrylate, lauryl methacrylate, methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, iso-butyl vinyl ether, n-butyl vinyl ether, styrene, α-methylstyrene, acrylic Nitrile, methacrylonitrile, vinyl acetate, vinyl chloride, vinylidene chloride, vinyl fluoride, vinylidene fluoride, ethylene, propylene, isopropylene, chloroprene, butadiene and the like are exemplified, further acrylic acid, methacrylic acid, itaconic acid,
2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, allyl alcohol, N-methylol acrylamide, N-methylol methacrylamide, dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, acrylamide And monomers having a functional group such as methacrylamide. The above examples do not limit the invention. When the other vinyl monomer is used in combination with the vinyl monomer having an oxirane ring, the resulting polymer
5 to 20 parts by weight of the vinyl monomer having an oxirane ring is contained in 100 parts by weight of A.

[Carboxylic acid B] The carboxylic acid used in the present invention is a carboxylic acid having a pKa of 3 or less, and is preferably a polybasic acid. Examples thereof include oxalic acid, maleic acid, phthalic acid, fumaric acid, and malonic acid. Acid, citric acid, trimellitic acid, pyromellitic acid,
Aconitic acid, citraconic acid and the like.

[Compound C] Examples of the compound C containing a hydrolyzable silyl group include a usual silane coupling agent and its oligomer, a polymerizable silane coupling agent, and the like. , Ethyltrichlorosilane, n-propyltrichlorosilane, methyltrimethoxysilane, phenyltrimethoxysilane, aminopropyltrimethoxysilane, mercaptopropyltrimethoxysilane,

Embedded image

Embedded image γ-methacryloxypropyltrimethoxysilane, vinyltriacetoxysilane, vinyltrimethoxysilane,
A condensation product obtained by condensing a compound having a hydrolyzable silyl group with an acid catalyst, or a hydrolyzable compound having an unsaturated double bond among the compounds having a hydrolyzable silyl group. In the case of a vinyl monomer containing a decomposable silyl group, one or more of these polymers, or one or more of the vinyl monomers containing a hydrolyzable silyl group, and A copolymer of one or two or more other monomers copolymerizable with the monomer can be used. The other monomer copolymerizable with the vinyl monomer containing a hydrolyzable silyl group is the same as the vinyl monomer copolymerizable with the vinyl monomer having an oxirane ring described above. There is something.

[Blending] In the present invention, as described above, a polymer A containing a vinyl monomer having an oxirane ring, a carboxylic acid B, and a compound C further containing a hydrolyzable silyl group
The compounding ratio of the polymer A and the carboxylic acid B should be adjusted based on a desired curing speed. Since the curing speed is also affected by the number of carboxyl groups contained in the carboxylic acid B and the pKa, the type of the carboxylic acid B should be selected according to the desired curing speed. However, in general, the mixing ratio of the polymer A and the carboxylic acid B is 99: 1 to 50:50 by weight. As described above, the compound C is further added to the polymer A and the carboxylic acid B. In this case, the compound C is added to 100 parts by weight of the mixture of the polymer A and the carboxylic acid B. Add up to 50 parts by weight. If desired, a third component such as a pigment, a dye, an antioxidant, or a pH adjuster may be added to the above-mentioned composition.

[0010]

In the coating composition of the present invention, the carboxylic acid has the same catalytic action as the Lewis acid, and a polyether crosslinked chain of —COC— is formed from the oxirane ring by an electrophilic reaction. It is considered that the hydrolyzable silyl group is accelerated in the presence of the carboxylic acid B, and a silanol group is formed, followed by silane crosslinking to cure. This curing reaction proceeds smoothly even at a low temperature.

[0011]

【Example】

Synthesis Example 1 (Synthesis of Polymer A-1) A reactor equipped with a stirrer, a condenser, and a thermometer was charged with 50 parts by weight of toluene and 50 parts by weight of n-butyl acetate, and was heated at 80 ° C.
, And the monomer mixture having the following formulation was continuously added dropwise over 3 hours. Methyl methacrylate 40 parts by weight Butyl acrylate 30 ２− 2-hydroxyethyl methacrylate 10 ジ ル glycidyl methacrylate 20 〃 AIBN (azobisisobutyronitrile) 1 後 After dropwise addition, the reaction was maintained at 80 ° C. for 3 hours, and then cooled to room temperature. Thus, a polymer A-1 was obtained. The obtained polymer A-1 had a solid content of 50% by weight and a viscosity U (Gardner Holtz).

Synthesis Example 2 (Synthesis of Polymer A-2) In a reactor similar to Synthesis Example 1, 50 parts by weight of toluene and 50 parts by weight of n-butyl acetate were placed, and heated and stirred at 80 ° C. to obtain the following formulation Was continuously added dropwise over 3 hours. Methyl methacrylate 40 parts by weight Butyl acrylate 30 〃 2-hydroxyethyl methacrylate 10 〃 METHB 20 〃 (methacrylate containing an alicyclic epoxy group (manufactured by Daicel Chemical Co., Ltd.)) AIBN (azobisisobutyronitrile) 1 後After continuing the reaction for 3 hours while maintaining the temperature, the mixture was cooled to room temperature to obtain a polymer A-2. The obtained polymer A-2 had a solid content of 50% by weight and a viscosity V.

Synthesis Example 3 (Synthesis of Compound C-1) Into the reactor used in Synthesis Example 1, 50 parts by weight of toluene and 50 parts by weight of isopropyl alcohol were added, and the mixture was heated and stirred at 80 ° C. The body mixture was dropped continuously over 3 hours. Methyl methacrylate 40 parts by weight Butyl acrylate 40 ２− 2-hydroxyethyl methacrylate 10 γ γ-methacryloxypropyltrimethoxysilane 10 〃 AIBN 1 後 After dropping, maintain the reaction at 80 ° C. for 3 hours, then cool to room temperature and add water. Compound C-1, which is a polymer containing a decomposable silyl group, was obtained. The obtained compound C-1 had a solid content of 50% by weight and a viscosity of U.

Synthesis Example 4 (Synthesis of Compound C-2) The following composition was charged into a reaction vessel, reacted at 10 ° C. for 2 hours, and further continued at 50 ° C. for 3 hours to obtain a hydrolyzable silyl group. A solution containing compound C-2 containing

Embedded image 236 parts by weight isopropyl alcohol 100〃water 36〃1% aqueous hydrochloric acid solution 1 は The resulting solution containing compound C-2 was purified by distillation under reduced pressure to obtain a viscous, colorless and transparent compound C-2 having a viscosity Z. .

Examples and Comparative Examples Table 1 shows the formulations of the coating compositions of Examples 1 to 4 and Comparative Examples 1 to 3. Table 1 shows the results of a coating test performed on the coating composition. According to Table 1, all of the coating compositions of the present invention have high hardness and good weather resistance and adhesion, but Comparative Example 1 which does not contain the compound C containing a hydrolyzable silyl group is compared with Example 2. As a result, the gel fraction was slightly inferior, and Comparative Examples 2 and 3 using a carboxylic acid catalyst having a pKa of 3 or more had lower hardness and lower weather resistance and adhesion than the coating composition of the present invention.

[0016]

[Table 1]

[0017]

【The invention's effect】

Therefore, in the present invention, since the curing of the coating film of the coating composition proceeds smoothly at normal temperature or low temperature, a coating film having high coating film hardness and good weather resistance, chemical resistance and adhesion can be obtained.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Toshie Kariya 8-3 Ninocho, Mizuho-ku, Nagoya-shi, Aichi Pref. Inside Natlab Paint Co., Ltd. (72) Inventor Yutaka Sakai 8 Ninocho, Mizuho-ku, Nagoya-shi, Aichi No. 3 Inside Natco Paint Co., Ltd. (72) Susumu Kawakami 8-3, Ninocho, Mizuho-ku, Nagoya City, Aichi Prefecture Inside No. 3 Natco Paint Co., Ltd. (72) Inventor, Hironori Hatano, Hiroshima No. 8-3, Natoco Paint Co., Ltd. (56) References JP-A-60-217230 (JP, A) JP-A-2-289642 (JP, A) JP-A-62-175928 (JP, A) 57-21465 (JP, A) JP-A-3-277646 (JP, A) JP-A-4-149289 (JP, A) Kunio Ito "Silicone Handbook First Edition No. 1""Shu" (August 31, 1990) Published by Nikkan Kogyo Shimbun, page 55, bottom line 5-page 57, line 2; page 65, bottom line 5-2 Compact Edition 32nd Edition "(1989), published by Kyoritsu Shuppan Co., Ltd., Vol. 8, p. 793 (58) Fields investigated (Int. Cl. ⁷ , DB name) C09D 163/00-163/10

Claims (1)

(57) [Claims] (1) one or more kinds of vinyl monomers having an oxirane ring and one or more kinds of other vinyl monomers copolymerizable with the vinyl monomer having an oxirane ring; Of a copolymer A containing 5 to 20 parts by weight of a vinyl monomer having an oxirane ring in 100 parts by weight of the copolymer, and 99: 1 of a carboxylic acid B having a pKa of 3 or less.
A coating composition comprising 5 to 50 parts by weight of a compound C having a hydrolyzable silyl group, based on 100 parts by weight of a mixture having a weight ratio of about 50:50.