Patent ID: 7888439
Filing Date: 2011-02-15
Classification: C08F,C08L,C09D

Abstract:
1. 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 mixture A of olefinically unsaturated, free-radically polymerizable monomers, comprising at least one olefinically monounsaturated monomer with at least one acid group in a proportion corresponding to an acid value of mixture A of 10 to 100 mg of KOH/g and 0.5 to 5 wt. % of at least one olefinically polyunsaturated monomer, in the aqueous phase, 2) neutralization of acid groups of the polymer formed in process step 1) and 3) free-radical polymerization of at least one mixture B of olefinically unsaturated, free-radically polymerizable monomers, comprising at least one olefinically monounsaturated monomer with at least one acid group in a proportion corresponding to an acid value of mixture B or each of the mixtures B of 0 to below 5 mg of KOH/g, at least one olefinically monounsaturated monomer with at least one hydroxyl group in a proportion corresponding to a hydroxyl value of mixture B or each of the mixtures B of 0 to below 5 mg of KOH/g and at least one olefinically polyunsaturated monomer in a proportion of 0.5 to 5 wt. %, relative to mixture B or each of the mixtures B, in the presence of the product obtained in process step 2), wherein the monomer composition of mixtures A and B is selected in such a manner that the calculated glass transition temperature (Tg) of a copolymer composed of a combination of only the olefinically monounsaturated monomers of mixtures A and B is in the range from 30 to 100° C., 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.