Method of forming coating films
AssigneeKansai Paint Co., Ltd.
InventorsAkira Kasari, Satoru Ito, Shigeru Nakamura
Life of this patent
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Abstract
A method for forming a coating film by sequentially forming a pigmented base coat and a clear top coat on a substrate. The pigmented base coat composition includes (1) an OH-containing resin, (2) an amino resin, (3) a polyorganosiloxane resin a number average molecule weight of at least 1,000 and having at least two groups per molecule selected from a silanol group and an alkoxysilane group and (4) a flaky metal or a mica powder in (5) an organic solvent. The clear top coat composition includes (1) an OH- and epoxy-containing base resin which additionally contains at least one of a silanol group and a hydrolyzable group bound directly to a silicon atom, (2) a curing catalyst and (3) an organic solvent.
Claims8
A method of forming a coating film by forming in sequence a pigmented base coat and a clear top coat on a substrate followed by finishing by the two-coat one-bake technique, the method being characterized by using, as a coating composition for pigmented base coat formation, an organic solvent-based coating composition comprising,
- (1) an OH-containing resin,
- (2) an amino resin,
- (3) a crosslinking agent which has, on an average, at least two groups, per molecule, each selected from the group consisting of a silanol group and an alkoxysilane group and which has a number average molecular weight of at least 1,000, said crosslinking agent being (A) or (B) as defined below;
- (A) a polyorganosiloxane which is prepared by subjecting silane compound(s) comprising not less than 30% by weight, based on the total weight of silane compound, of trifunctional silane of the general formula
- R.sup.1.sub.x Si(OR.sup.2).sub.4-x (I)
- wherein R.sup.1 and R.sup.2 may be the same or different and each is a hydrocarbon group containing 1 to 13 carbon atoms and x is 1, to hydrolysis condensation,
- (B) an epoxy-containing polyorganosiloxane which is prepared by subjecting to hydrolysis cocondensation a silane represented by the general formula (I) wherein x is 1, 2 or 3 and an epoxy-containing silane of the general formula ##STR8## wherein R.sup.3 and R.sup.4 may be the same or different and each is a hydrocarbon group containing 1 to 13 carbon atoms, y is 1, 2 or 3, G is a group of the formula (III) or (IV) given below:
- ##STR9## wherein R.sup.5 is a bivalent hydrocarbon group containing 1 to 13 carbon atoms and the R.sup.6 groups may be the same or different and each is a hydrogen atom or a methyl group, providing that the silane of formula (I) in which x is 1 and the silane of formula (II) in which y is 1 combinedly account for not less than 30% by weight in the total weight of the hydrolyzed silane compounds,
- (4) a flaky metal powder and/or a mica powder, and
- (5) an organic solvent,
- and using, as a coating composition for clear top coat formation, a composition comprising,
- (1) a base resin, wherein the base resin is (i) a resin mixture comprising three component resins comprising (a) an OH-containing resin, (b) an epoxy-containing resin and (c) a resin containing one or more groups each selected from the group consisting of a silanol group and a hydrolyzable group bound directly to a silicon atom, (ii) a resin mixture comprising two component resins comprising (a) an epoxy-containing resin and (b) a resin containing one or more groups each selected from the group consisting of a silanol group and a hydrolyzable group bound directly to a silicon atom, either one or both of the resins being OH-containing resins, or (iii) an OH- and epoxy-containing base resin which further contains at least one group selected from the group consisting of a silanol group and a hydrolyzable group bound directly to a silicon atom,
- (2) a curing catalyst, and
- (3) an organic solvent.
Dependencies are inferred from the claim text.