Patent ID: 8530574

Claim:
An aqueous polymer dispersion obtained by a process comprising: (a) polymerizing, in the presence of at least one emulsifier and a free-radical initiator, a monomer composition I comprising in an aqueous polymerization medium: 0.1% to 10% by weight of a monomer A, a monomer B, or both; and 0.1% to 10% by weight of a hydrophilic monomer of formula (1) wherein n represents 0 to 2, R 1 , R 2 and R 3 independently represent hydrogen or a methyl group, X represents oxygen or an imino group (NH), and Y represents hydrogen, an alkali metal, or ammonium, to form an in situ seed, comprising hydrophilic and hydrophobic monomers; then (b) polymerizing a a monomer composition II comprising: 40%-60% by weight of the monomer A, a homopolymer of which has a glass transition temperature below 20° C.; 15%-30% by weight of the monomer B, a homopolymer of which has a glass transition temperature above 50° C.; 0.1%-5% by weight of a monomer C comprising an α,β-unsaturated carboxylic, sulfonic, phosphonic acid, carboxamide, or mixture thereof, which is copolymerizable with the monomer B; 0%-5% by weight of a monomer D comprising an ethylenically unsaturated monomer comprising a keto group, a non-C, ethylenically unsaturated, and nitrogen-comprising adhesion monomer, or both; and 0%-5% by weight of an ethylenically unsaturated monomer E; and (c) polymerizing a monomer composition III comprising: 0%-5% by weight of the monomer A, a homopolymer of which has a glass transition temperature below 20° C.; 10%-30% by weight of the monomer B, a homopolymer of which has a glass transition temperature above 50° C.; 0.1%-5% by weight of the monomer C comprising an α,β-unsaturated carboxylic, sulfonic, phosphonic acid, carboxamide, or mixture thereof, which is copolymerizable with the monomer B; 0%-5% by weight of the monomer D comprising an ethylenically unsaturated monomer comprising a keto group, a non-C, ethylenically unsaturated, and nitrogen-comprising adhesion monomer, or both; and 0%-5% by weight of the ethylenically unsaturated monomer E, wherein the sum of the monomer compositions I+II+III equals 100%.