Core/shell copolymer dispersion whose shell comprises hydrolyzable organosilicon comonomers

A core/shell copolymer dispersion having a solid content of from 45 to 65% whose shell comprises hydrolyzable organosilicon comonomers, the proportion of the shell in the core-shell copolymer being from 2 to 25% by weight and the shell comprised of a copolymer consisting essentially of a) at least 70% by weight, based on the overall weight of the shell, of acrylic and/or methacrylic C.sub.1 to C.sub.10 alkyl esters of which from 20 to 80% by weight, based on the overall weight of a), have a water-solubility of not more than 2 g/l and from 80 to 20% by weight, based on the overall weight of a), have a water-solubility of at least 10 g/l, b) from 5 to 25% by weight, based on the overall weight of the shell, of one or more ethylenically unsaturated, functional and water-soluble monomers and wherein (b) is comprised of by weight, at least 25% and up to and including 100% of unsaturated carboxylic acids, and c) from 0.01 to 10% by weight, based on the overall weight of the shell, of one or more olefinically unsaturated, hydrolyzable silicon compounds of the general formula R.sup.1 --Si (OR.sup.2).sub.3 in which R.sup.1 is an organic radical which is olefinically unsaturated in the .omega.-position, and R.sup.2, which is identical or different at each occurrence, is a primary and/or secondary alkyl or acyl radical which is optionally substituted with alkoxy groups, and whose core, makes up a proportion of from 75 to 98% by weight of the overall weight of the core/shell copolymer, comprised of a polymer consisting essentially of d) one or more comonomers from the group consisting of vinyl esters, acrylic and/or methacrylic esters, vinyl chloride, aromatic vinyl compounds and ethylene.