Aqueous binder compositions

Abstract

The present invention relates to aqueous binder compositions which are based on aqueous multistage polymer dispersions, to the uses of such binder compositions, and to coating compositions comprising them. The aqueous binder composition comprises: a) a polymer P in the form of an aqueous multistage polymer dispersion of dispersed polymer particles, where the polymer particles comprise a first polymer having a glass transition temperature of at least 30° C. and being made of ethylenically unsaturated monomers M-A, and a second polymer having a glass transition temperature of not more than 20° C. and being made of ethylenically unsaturated monomers M-B, where the ethylenically unsaturated monomers M-A and M-B together comprise: i. 85% to 99.45% by weight, preferably 87.5% to 97% by weight and in particular 90% to 95.5% by weight, based in each case on the total amount of monomers M-A+M-B, of at least one neutral, monoethylenically unsaturated monomer M1 having a solubility in water of at most 50 g/l at 25° C. and 1 bar; ii. 0.5% to 10% by weight, preferably 1% to 7.5% by weight and in particular 1.5% to 6.5% by weight, based in each case on the total amount of monomers M-A+M-B, of at least one neutral, monoethylenically unsaturated monomer M2 having a solubility in water of at least 100 g/l at 25° C. and 1 bar; iii. 0.05 to 0.5% by weight, preferably 0.15% to 0.5% by weight and in particular 0.3% to 0.5% by weight, based in each case on the total amount of monomers M-A+M-B, of one or more monoethylenically unsaturated monomers M3 having an acidic group; and iv. optionally from 0 to 5% by weight and in particular from 0 to 4.5% by weight, based in each case on the total amount of monomers M-A+M-B, of one or more monomers M4 having at least two non-conjugated ethylenically unsaturated double bonds; and b) at least one carbodiimide having at least two carbodiimide moieties, which are bound to an aliphatic carbon atom.