Process for making cationic structured particle latexes using reactive polymeric surfactants

Claim 1

In a process for preparing a latex by free radical catalyzed emulsion polymerization in an aqueous medium in at least one stage, the improvement of introducing a reactive polymeric surfactant in at least one stage of the polymerization process to prepare a structured particle latex; said reactive polymeric surfactant being a substantially linear synthetic water-soluble surfactant whose polymeric backbone is derived from the polymerization of one or more ethylenically unsaturated monomers and which polymeric surfactant has a number average molecular weight of from about 500 to about 40,000 and bears, per gram of such reactive polymeric surfactant, from about 1 to about 4 milliequivalents of pH independent randomly distributed ionic groups and, per polymeric surfactant molecule, and average of at least one water-insensitive reactive fractional group selected from the group consisting of ethylenically unsaturated groups, sulfhydryl groups and epoxy groups; said ethylenically unsaturated monomers being (a) one or more hydrophobic monomers or (b) one or more hydrophobic monomers together with at least one hydrophilic nonionic monomer or ionic monomer or mixtures thereof in such proportions that the amount of the hydrophilic nonionic monomer is less than about 15 percent by weight, based on the weight of the reactive polymeric surfactant; said functional group being either in the polymer backbone or pendant therefrom and providing a crosslinking or grafting site; and said structural particle latex having structured particles consisting of a water-insoluble, non-ionic organic polymer core encapsulated with a layer of a copolymer having pH independent ionic groups chemically bound at or near the outer surface of the structured particle; the amount of said ionic groups being sufficient to provide at least a major portion of the colloidal stability but insufficient to make the polymer water-soluble.