Color plus clear coatings employing polyepoxides and polyacid curing agents in the clear coat
AssigneePPG Industries, Inc.
InventorsDennis A. Simpson, Debra L. Singer, Rostyslaw Dowbenko, William P. Blackburn, Charles M. Kania
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Abstract
A color-plus-clear coating system is disclosed. A pigmented or colored base coat is first applied to a substrate followed by the application of a transparent top coat to the base coat. The transparent top coat composition is a liquid crosslinkable composition comprising a polyepoxide and a polyacid curing agent. The polyepoxide-polyacid curing agent in the transparent top coat provides a composite coating with outstanding gloss and distinctness of image making the composite coating particularly useful as an automotive top coat.
Claims33
A process for applying a composite coating to a substrate which comprises applying to the substrate a colored film-forming composition to form a base coat and applying to said base coat a clear film-forming composition to form a transparent top coat over the base coat characterized in that the clear film-forming composition is a liquid crosslinkable composition comprising a polyepoxide and a polyacid curing agent having at least two carboxyl groups per molecule, the equivalents of carboxyl per epoxy in the clear film-forming composition being from about 0.3 to 3.0 and sufficient to form a crosslinked coating.
A process for applying a composite coating to a substrate which comprises applying to the substrate a colored film-forming composition to form a base coat and applying to said base coat a clear film-foming composition to form a transparent top coat over the base coat characterized in that the clear film-forming composition is a liquid composition having a resin solids content of at least 50 percent by weight comprising a polyepoxide which is a copolymer of a glycidyl acrylate or methacrylate with at least one other coplymerizable ethylenically unsaturated monomer having a number average molecular weight between 1000 and 20,000 and a Tg of less than 50.degree. C. and a polyacid curing agent having at least two carboxyl groups per molecule;
- the equivalent ratio of carboxyl to epoxy in the clear film-forming composition being from 0.8 to 1.5:1 and sufficient to form a crosslinked coating.
Dependencies are inferred from the claim text.