Waterborne primer with improved chip resistance
Patent No. U.S. 6,579,928 B2
BASF Corp. has been granted a patent for a composite coating. It is comprised of a substrate; at least one primer coating layer over the substrate that is obtained by curing a primer coating composition comprising a polyurethane polymer, the polyurethane polymer having a glass transition temperature of approximately 0° C or less; a dispersed acrylic polymer polymerized in the presence of the dispersed polyurethane polymer, the acrylic polymer having a glass transition temperature that is at least about 20° C higher than the glass transition temperature of the polyurethane polymer; and a crosslinking component that is reactive with at least one of the polyurethane polymer and the acrylic polymer; and at least one topcoat layer over the primer coating layer.