Process for preparing aqueous coatings comprising dispersible epoxy resin-acid polymer ester

Claim 1

A process for preparing an aqueous dispersion composition comprising: A. copolymerizing a monomer mixture which includes at least 30 percent by weight of carboxyl-containing monomer to form a carboxyl containing copolymer in the presence of an epoxy resin containing aliphatic carbon atoms and 1,2-epoxy groups in which said epoxy resin constitutes at least 40 weight percent of the solids in the resulting composition; B. reacting the composition obtained in A under esterification conditions in the presence of a tertiary amine esterification catalyst wherein the equivalents of 1,2-epoxy groups in said epoxy resin are in excess of the equivalents of tertiary amine, to obtain a product substantially free of epoxy groups and containing hydroxy ester groups from the reaction between said carboxyl group and at least 5 percent of said 1,2-epoxy groups; and C. dispersing said composition in water with the addition of ammonia or amine neutralizing agent; in which a polymer different from said carboxyl containing copolymer of step A is prepared in situ prior to dispersing the mixture in water in step C.