| 摘要 |
Building materials containing copolymers derived from vinyl ester, (meth)acrylic ester and optionally ethylene comonomers, stabilized with a polyvinylalcohol protective colloid, as their aqueous dispersions or as redispersible polymer powders which are redispersible in water, exhibit improved processing properties and set properties. The copolymers are obtained by emulsion or suspension copolymerization in an at least two step process wherein a) the vinyl ester component is polymerized, optionally with ethylene and further copolymerizable comonomers, to a conversion of from 90 to 100% by weight in a first step, and b) the ester(s) of (meth)acrylic acid are subsequently added and polymerized in a second step. The copolymer dispersion obtained may be dried to form a redispersible copolymer powder.
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