Patent ID: 11098147

Abstract:
An aqueous polymer dispersion is produced by multistage emulsion polymerization, in which a monomer composition I comprising 19 to 29 wt % hard monomers and 64 to 74 wt % soft monomers is polymerized to produce a first polymer phase and then a monomer composition II comprising 65 to 95 wt % hard monomers and 5 to 35 wt % soft monomers is polymerized to produce a second polymer phase. Monomer composition I also comprises from 1 to 5 wt % of at least one monomer selected from ethylenically unsaturated sulfonic acids, phosphonic acids, phosphoric acids, carboxylic acids, carboxylic amides, carboxylic anhydrides and mixtures thereof and 1 to 7.5 wt % of ethylenically unsaturated monomers containing keto groups. The weight ratio of monomer composition I to monomer composition II ranges from 50:50 to 65:35 and the polymer dispersion also contains a water-soluble cross-linking component selected from polyfunctional carboxylic hydrazides and/or polyfunctional amines.