Patent ID: 8883880

Claim:
A soluble shell polymer composition comprising from 5 to 20 weight percent of an alkali soluble emulsion polymer shell and from 80 to 95 weight percent of an alkali insoluble emulsion polymer core, wherein: the alkali soluble emulsion polymer shell comprises from 85 to 95 weight percent structural units of an acrylic monomer and from 5 to 15 weight percent structural units an acrylic acid monomer, based on the weight of the alkali soluble emulsion polymer; and wherein: the alkali insoluble emulsion polymer core comprises from 0.1 to 5 weight percent structural units of a phosphorus acid monomer and from 80 to 99.9 weight percent structural units of an acrylic monomer, based on the weight of the alkali insoluble emulsion polymer; wherein the soluble shell polymer composition is stabilized by 0.5 to 5 weight percent, based on the weight of the soluble shell polymer, of a surfactant of the formula R—(OCH 2 CH 2 ) 2-6 OSO 3 − M + , where R is a linear, branched, or cyclic C 8 -C 24 alkyl or C 12 -C 30 aralkyl group and M + is a counterion.