| abstract |
A process for the preparation of stable aqueous polymer dispersions which contain an alkenyl-aromatic compound as copolymerized units, by polymerizing monomer mixtures which contain n (a) not less than 2% by weight of an alkenyl-aromatic compound and n (b) from 0.5 to 10% by weight of an ethylenically unsaturated C 3 -C 5 -carboxylic acid and/or its amide and/or its nitrile and/or an ethylenically unsaturated monomer containing sulfonic acid groups, with or without n (c) acrylic acid esters, methacrylic acid esters and/or butadiene n in aqueous emulsion in the presence of a polymerization initiator, with or without an emulsifier and with or without a polymerization regulator, at a pH below 7, in the presence of from 0.2 to 2% by weight of formaldehyde. |