Patent ID: 6020435
Filing Date: 2000-02-01
Classification: C08F,Y10S

Abstract:
A process for preparing emulsion polymer particles comprising:(a) providing an aqueous emulsion of(i) multi-stage emulsion polymer, comprising a core stage polymer and a shell stage polymer,wherein the core stage polymer comprises, as polymerized units, from 5 to 100 percent by weight, based on the weight of the core stage polymer, of hydrophilic monoethylenically unsaturated monomer, and from 0 to 95 percent by weight, based on the weight of the core stage polymer, of at least one nonionic monoethylenically unsaturated monomer; andwherein the shell stage polymer comprises, as polymerized units, at least 50 percent by weight of nonionic monoethylenically unsaturated monomer;(ii) monomer at a level of at least 0.5 percent by weight based on the weight of the multi-stage emulsion polymer; and(iii) swelling agent under conditions wherein there is no substantial polymerization of the monomer; and(b) reducing the level of monomer by at least fifty percent.