Free-radical polymerization process

A process for free-radically initiated heterophase polymerization, comprising polymerization of one or more ethylenically unsaturated monomers in a phase dispersed in the continuous phase, characterized in that, before or during the polymerization, one or more additives which are soluble in the continuous phase and insoluble in the dispersed phase are added which terminate the polymerization of the ethylenically unsaturated monomers in the continuous phase additives added, the one or more additives being selected from the group consisting of styryl-group-bearing polar or salt-like compounds which have unfavorable copolymerization characteristics with the monomers of the disperse phase;

• wherein the ethylenically unsaturated monomers are selected from the group consisting of one or more vinyl esters of unbranched or branched alkylcarboxylic acids having 1 to 15 C atoms;
• mixtures consisting of vinyl acetate and ethylene;
• mixtures consisting of vinyl acetate, ethylene, and a vinyl ester of α-branched monocarboxylic acids having 9 to 11 C atoms;
• and mixtures consisting of vinyl acetate and one or more monomers from the group consisting of methyl acrylate, ethyl acrylate, propyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, and optionally ethylene;
• wherein the ethylenically unsaturated monomers may optionally include macromers and/or 0.1% to 20% by weight of one or more auxiliary monomers, based on the total weight of the monomers.