Process for the production of aqueous binder latices

摘要

A process for the production of aqueous binder latices by multistage emulsion polymerization in the aqueous phase, comprising the successive steps:
1) free-radical polymerization of a monomer mixture A comprising acidic monomers in a proportion corresponding to an acid value of 10 to 100 mg of KOH/g and olefinically polyunsaturated monomers in a proportion of 0.5 to 5 wt%,
2) neutralization of acid groups of the polymer formed in process step 1) and
3) free-radical polymerization of at least one monomer mixture B comprising acidic monomers in a proportion corresponding to an acid value of mixture(s) B of 0 to below 5 mg of KOH/g, hydroxyl-functional monomers in a proportion corresponding to a hydroxyl value of mixture(s) B of 0 to below 5 mg of KOH/g and olefinically polyunsaturated monomers in a proportion of 0.5 to 5 wt%,
wherein mixture A and/or the at least one mixture B comprise at least one aromatic monomer in a total proportion of 10 to 50 wt.-% relative to the sum of the weights of mixtures A and B, wherein the ratio by weight of mixture A to the at least one mixture B is from 15:85 to 85:15 and wherein neutralization is not begun in process step 2) until at least 90 wt.% of the monomers of mixture A have been polymerized to completion.