Abstract: A waterborne coating composition having a total solids content at application of greater than 30 percent, contains pigment and a dispersion of polymeric microparticles in an aqueous medium. The microparticles contain greater than 30 percent by weight based on the microparticles of a substantially hydrophobic polymer which is essentially free of repeating acrylic or vinyl units in the backbone, has a molecular weight greater than 300 and is adapted to be chemically bound into the cured coating composition. The aqueous medium of the microparticle dispersion is substantially free of water soluble polymer.

Abstract: A method for preparing polymer microparticles which are stably dispersed in a nonaqueous medium involves:(a) mixing into a nonaqueous medium a polymerizable component at least 20 percent of which is insoluble in the nonaqueous medium, said polymerizable component comprising at least one polymerizable species;(b) subjecting the mixture of (a) to stress sufficient to particulate the mixture;(c) polymerizing the polymerizable component within each particle under conditions sufficient to produce polymer microparticles stably dispersed in the nonaqueous medium, said polymer microparticles being insoluble in the nonaqueous medium and the nonaqueous medium being substantially free of dissolved polymer, said polymer microparticles further characterized in that less than 20 percent of the polymer microparticles have a mean diameter greater than 5 microns.

Abstract: A stable, nonaqueous polyurethane microparticle dispersion is characterized in that less than 20 percent of the polymer microparticles have a mean diameter greater than 5 microns, further characterized in that at a total solids content of 60 percent the Brookfield viscosity is less than 1000 centipoise measured at 50 RPM using a number 3 spindle at 25.degree. C., the polyurethane being prepared from reactants which are substantially free of acrylic polymer and the polyurethane being further characterized in that it is substantially free of unreacted polyisocyanate monomer.