US 5,962,574 A · Wet-on-wet primer with low film build U.V. light protection

Abstract

A sprayable, solvent-borne, primer composition for use as a first coat on light-sensitive, automotive plastic parts. The primer serves as a barrier to block ultraviolet light penetration to the underlying substrate and to prevent migration of substrate degradation and by-products up into the topcoat finishes. The primer is a solvent blend of a film-forming crosslinkable polymer resin, a crosslinker for the resin, a catalyst, carbon black pigments surface modified with a polymer dispersant and an organic pigment derivative co-dispersant, crosslinked polymer microgel particles, and U.V. absorbers and optional antioxidants. The surface modification on the carbon black pigments results in higher pigment loadings, which, in turn, imparts U.V. light protection at exceptionally low dry film builds. Furthermore, the microgel particles cause the primer to build in viscosity and set up a gel structure in its uncured state, which allows the primer to be overcoated wet-on-wet with automotive topcoat finishes and cured simultaneously in a single bake without diminishing the topcoat appearance and physical properties. The need for a separate primer bake prior to topcoat application is, therefore, eliminated.

Claims30

Dependent claims

A primer coating composition capable of protecting a substrate susceptible to degradation by ultraviolet light, said composition serving as a primary coat on said substrate beneath a multilayer color base coat/clear top coat finish, comprising a sprayable, continuous film-forming solvent blend of:

a) a film-forming polymer resin having crosslinkable functional groups;
b) a crosslinker for curing said resin;
c) a catalyst for accelerating said curing;
d) ultraviolet light-blocking pigments in an amount sufficient to achieve substantially complete ultraviolet light block out through a cured coating film formed from said composition at a dry film thickness of about 5 .mu.m, said pigments being treated with a dispersant in an amount sufficient to render said composition sprayable and flowable into a continuous film;
and,
e) polymer microgel particles in an amount sufficient to prevent intermixing and enable hold out of said color base coat or said color base coat/clear top coat finish upon being applied over said composition wet-on-wet and simultaneously cured therewith.

3 more elements

Dependencies are inferred from the claim text.

Wet-on-wet primer with low film build U.V. light protection

Life of this patent

Wet-on-wet primer with low film build U.V. light protection

Life of this patent

Abstract

Claims30