Aqueous coating compositions

Abstract

An aqueous coating composition containing: (a) an aqueous carrier medium: (b) a pigment having a pH below 7.0; (c) an AB block copolymer pigment dispersant resin of (1) an A block of a hydrophobic polymer having amine groups; and (2) a B block of a hydrophilic polymer having hydroxyl groups and carboxyl groups; the AB block copolymer has a number average molecular weight of 5,000-20,000 and contains 20-80% by weight of a polymeric A segment and correspondingly 80-20% by weight of a polymeric B segment; wherein the pigment and the dispersant are present in a pigment to dispersant weight ratio of 0.1/1-20/1; (d) a film forming polymeric binder containing carboxyl groups and (e) a crosslinking agent which on curing of the coating composition will react with the carboxyl and hydroxyl groups of the AB block copolymer and the carboxyl groups of the film forming polymeric binder. Pigment dispersions of the AB block copolymer and process for forming the dispersions also are part of this invention.

Dependencies are inferred from the claim text.