Patent ID: 8552126

Claim:
A process for preparing an aqueous polymer dispersion, the process comprising: free-radical aqueous emulsion polymerizing a reaction mixture comprising a polar monomer having a water solubility of greater than 50 g/liter, measured at 20° C., to obtain an aqueous dispersion comprising an addition polymer P, wherein the dispersed addition polymer P comprises, in free-radically copolymerized form, at least one polar monomer having a water solubility of greater than 50 g/liter (measured at 20° C.), and wherein the polar monomer is metered during the polymerization process at a gradient, wherein the addition polymer P comprises, copolymerized in free-radically polymerized form: (A) at least one monomer selected from the group consisting of an ethylenically unsaturated acid and a conjugated base of the ethylenically unsaturated acid; (B) at least one monomer of formula (I) wherein n is 0 to 2, R1, R2, and R3 are, independently of one another, hydrogen, or a methyl group, X is O or NH, and Y is H, an alkali metal, or NH 4 ; and (C) at least one free-radically polymerizable monomer which comprises, copolymerized in free-radically polymerized form, at least two COOX groups, where X is H or a metal, wherein at least one selected from the group consisting of monomers (B) and monomer (C) is metered into the reaction mixture during polymerization at a gradient rate, wherein the reaction mixture of the addition polymer P comprises no molecular weight regulator; and wherein the addition polymer P comprises no vinyl aromatic monomers.