Abstract: Polymers are prepared from olefinically unsaturated monomers in an aqueous medium using a free radical initiator system which is soluble in this medium and consists of an oxidizing agent, a reducing agent and an iron salt, by a process in which a corresponding redox initiator system which contains a vanadium salt is used in addition to this iron-containing redox initiator system, and the content of olefinically unsaturated residual monomers in aqueous polymer mixtures or solutions is reduced by this process.

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(a) not less than 2% by weight of an alkenyl-aromatic compound and(b) from 0.5 to 10% by weight of an ethylenically unsaturated C.sub.3 -C.sub.5 -carboxylic acid and/or its amide and/or its nitrile and/or an ethylenically unsaturated monomer containing sulfonic acid groups, with or without(c) acrylic acid esters, methacrylic acid esters and/or butadienein 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.

Abstract: Emulsion copolymerization of acrylic or methacrylic acid esters with from 0.3 to 10% by weight of .alpha.,.beta.-monoolefinically unsaturated monocarboxylic acids and/or dicarboxylic acids and/or their amides, with or without up to 25% by weight of styrene, acrylonitrile, vinyl acetate and/or vinyl chloride, using the emulsion feed process, gives particularly concentrated copolymer dispersions if an emulsifier system of 0.01-5.0% by weight of a sulfuric acid half-ester of an oxyalkylated alkylphenol and 0.01-1% by weight of a dialkyl sulfosuccinate, where alkyl is of 6 to 18 carbon atoms, is employed and the polymerization is carried out at pH 2-6.