Patent ID: 8480853

Claim:
A method for making paper or paperboard comprising adding ionic crosslinked polymeric microparticles to a paper making pulp to form a treated pulp, and forming the treated pulp into paper or paperboard, wherein the ionic crosslinked polymeric microparticles comprise a crosslinked acrylic acid-acrylate copolymer, wherein the copolymer having the structure: where R is hydrogen or an alkyl group having 1-4 carbon atoms; R 1 is hydrogen or an alkyl group having 1-20 carbon atoms, an alkoxyl group having 1-20 carbon atoms, or an alkoxyalkyl group with alkoxy and alkyl independently having 1-20 carbon atoms; wherein x is a weight percent from 1%-99% by weight based on total weight of the copolymer and y is a weight percent from 99%-1% by weight based on total weight of the copolymer; and the copolymer having a number average molecular weight of from about 5,000 to about 1,000,000.