Coating composition containing cross-linked microparticles

Claim 1

A coating composition for the preparation of coatings on substrates, consisting essentially of: (a) 10 to 60% by weight of a film-forming synthetic resin selected from the group consisting of acrylic polymers, vinyl ester copolymers, alkyd resins, polyester resins, nitrogen containing condensation resins, mixtures thereof, and mixtures thereof with cellulose esters; (b) 40 to 80% by weight of an organic solvent in which said synthetic resin is soluble; (c) 2.5 to 25% by weight of polymer microparticles having ionic or a mixture of polar and ionic groups on their surfaces and having a diameter of 0.01 to 5 microns prepared by emulsion-polymerizing ethylene-unsaturated monomers in an aqueous phase, at least one of said monomers selected from the group consisting of acrylic acid, methacrylic acid, and --OH substituted alkyl esters thereof and containing polar functional groups selected from hydroxy groups, tertiary amine, sulfonic acid, and carboxylic acid groups, and at least another of said monomers selected from the group consisting of an alkyl ester of acrylic acid, an alkyl ester of methacrylic acid, styrene and methyl styrene, said another of said monomers being free from said polar functional groups and a multifunctional cross-linking agent present in an amount greater than about 10% to 70% by weight of the total weight of said ethlenically unsaturated monomers and cross-linking agent, said cross-linking agent cross-linking said microparticles to a degree that said polar and said ionic groups are fixed on the surface of said microparticles, and subsequently removing water from said aqueous phase, said microparticles being insoluble in the solution of said synthetic resin in said organic solvent and having said polar and ionic groups fixed on the surfaces, rearrangement of said polar and ionic groups into the particle interior being prevented by the cross-linking from said cross-linking agent; and (d) 2 to 40% by weight of pigments.