| 摘要 |
<p>1. A copolymer which consists essentially of polymerized units of a) from 31 to 64% by weight of one or more vinyl-aromatics, b) from 24 to 65% by weight of one or more esters, free from unesterified carboxyl groups, of an alpha,beta-ethylenically unsaturated monocarboxylic acid or dicarboxylic acid, of 3 to 5 carbon atoms, with a branched or straight-chain monoalkanol of 1 to 14 carbon atoms, c) from 4 to 30% by weight of one or more carboxyl-containing alpha,beta-ethylenically unsaturated compounds of 3 to 14 carbon atoms, and d) from 0 to 5% by weight of other alpha,beta-ethylenically unsaturated compounds, not mentioned under a) to c) with the proviso that the sum of the percentages mentioned under a) to d) is 100, which copolymer has a K value, determined by the Fikentscher method, of from 18 to 60 and contains components (a), (b), (c) and (d) as polymerized units in such a ratio that the copolymer has an A value of from 180 to 220, which value can be calculated according to the following equation 100 . log SZ + 1,6 . see diagramm : EP0044399,P10,F3 where SZ is the acid number in mg of KOH/g of copolymer and see diagramm : EP0044399,P10,F4 is the sum of the corrected contents E1 -En , each in % by weight based on the copolymer, of COO groups in the particular alkyl (meth)acrylate comonomers b)1 - b)n, these contents in percent by weight being corrected by multiplying them by a factor of 0.7 for esters (b) of alpha-branched alkanols and by a factor of 0.8 for esters (b) of beta-branched alkanols.</p> |
