Patent ID: 8754151

Claim:
An aqueous multistage polymer dispersion, comprising: a soft phase having a glass transition temperature ranging from −30° C. to 0° C.; and a hard phase having a glass transition temperature ranging from 20° C. to 60° C., said soft phase and said hard phase each comprising at least one monomer of formula (I): wherein: n represents an integer of 0 to 2; R1, R2, R3 independently represent hydrogen or methyl group; X represents O or NH Y represents H, an alkali metal, or NH 4 ; a hard-to-soft stage ratio of the aqueous multistage polymer dispersion ranges from 25:75 to 95:5 based on relative weights; and the soft phase is a soft-phase copolymer comprising, to an extent of at least 80% and up to 99% by weight, at least one principal monomer selected from the group consisting of a C 1 to C 10 alkyl (meth)acrylate, an amide of an α,β-unsaturated C 3 -C 6 carboxylic acid, and a hydroxyalkyl ester of an α,β-unsaturated C 3 -C 6 carboxylic acid.