| abstract |
A particulate polymer A having a mean particle size of less than 1000 nm consists of a1: up to 99.8% by weight of at least one vinylaromatic monomer a1, a2: up to 99.8% by weight of at least one alkyl methacrylate a2 where the alkyl radical is of 1 to 8 carbon atoms, a3: up to 50% by weight of at least one polar, copolymerizable, ethylenically unsaturated monomer a3, a4: from 0.1 to 10% by weight of at least one polyfunctional, crosslinking monomer a4 and a5: from 0.1 to 15, preferably from 0.5 to 10, % by weight of at least one monomer a5 containing one or more acidic, basic or epoxy groups, the sum of the components a1, a2 and a3 being from 75 to 99.8% by weight, based on A, and the sum of a1, a2, a3, a4 and a5 being 100% by weight, based on A. |