| 摘要 |
A process for the preparation of vinylaromatic copolymer redispersion powders redispersible in water is by free-radical emulsion polymerization of a comonomer mixture including(a) one or more vinylaromatic comonomers,(b) one or more 1,3-diene comonomers (b1) or one or more comonomers (b2) from the group including the alkyl esters having 1 to 8 C atoms of acrylic acid or methacrylic acid and(c) 0.1 to 10% by weight, based on the total weight of the comonomer mixture, of one or more comonomers from the group including the ethylenically unsaturated mono- or dicarboxylic acids or the anhydrides thereof, the ethylenically unsaturated carboxamides, the ethylenically unsaturated sulfonic acid compounds and in each case the salts thereof,and drying of the aqueous copolymer dispersion obtainable thereby. One or more hydroxycarboxylic acids or the salts thereof are added to the aqueous copolymer dispersion in an amount of 3 to 40% by weight, based on the total weight of copolymer, before or during the polymerization or before the drying.
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