Patent ID: 9469760
Filing Date: 2016-10-18
CPC Classification: C08F,C08K,C08L,C09D

Claim Text:
1. A process comprising: a) contacting together sodium 4-vinylbenzene sulfonate, a phosphorous acid monomer, and a first acrylic monomer, under emulsion polymerization conditions to form a stable aqueous dispersion of first polymer particles, then; b) contacting the dispersion of the first polymer particles with sodium 4-vinylbenzene sulfonate; and a second acrylic monomer under emulsion polymerization conditions to form a stable aqueous dispersion of multistage polymer particles; wherein the weight percents of the first and second sulfur acid monomers are from 0.5 to 1.0 weight percent, based on the weight of the multistage polymer particles; the weight percent of the phosphorous acid monomer is from 0.4 to 2 weight percent, based on the weight of the multistage polymer particles; and the combined weight percents of the first and second acrylic monomers are from 30 to 99 weight percent, based on the weight of the multistage polymer particles; wherein the mole-mole ratio of the first sulfur acid monomer to the second sulfur acid monomer is from 0.5:1 to 3:1, and the multistage polymer has a T