Residual monomer content of aqueous polymer dispersions is reduced

摘要

A process for the reduction in the residual monomer content of aqueous polymer dispersions is carried out by the addition of a radical redox initiator system. A process for the reduction of the non-chemically bound residual content of an aqueous polymer dispersion (I) that contains compounds having ethylenically unsaturated groups (residual monomers), comprises the post treatment of the dispersion (I) with a radical redox initiator system (II). (II) contains (A) an oxidising agent consisting of compounds liberating hydrogen peroxide and compounds of formula (1); and (B) a reducing agent consisting of alpha -hydroxycarboxylic acids containing a hydroxymethine group and corresponding salts. R<1> = H, 1-8C alkyl or 6-12C aryl. The addition of (II) to (I) is such that (i) at least a portion of (B) is added to (I) followed by the simultaneous but spatially separate addition of the remainder of (B) with the total amount of (A); or (ii) at least a portion of (A) is added to (I) followed by the simultaneous but spatially separate addition of the remainder of (A) with the total amount of (B); or (iii) the simultaneous but spatially separate addition of the total amounts of (A) and (B).