Extrudable, low-migration organic silicone copolymers of high transparency, their preparation and use

A process for preparing organic silicone copolymers by polymerizing, by free-radical initiated polymerization, monomers comprising:

• a) from 30 to 99% by weight, based on the total weight of components a) and b), of one or more monomers selected from the group consisting of vinylaromatics, (meth)acrylic esters of C1-15 alcohols, vinyl esters of branched or unbranched C1-15 alkylcarboxylic acids, olefins, dienes, and vinyl halides, and
• b) from 1 to 70% by weight, based on the total weight of components a) and b), of a silicone component composed of a mixture of at least two diorganopolysiloxanes having the general formula R1aR3-aSiO(SiR2O)nSiR3-aR1a, in which each R is identical or different and denotes a monovalent, optionally substituted, C1-18 alkyl or C1-18 alkoxy radical, R1 denotes a polymerizable group, a is identical or different and denotes 0 or 1, at least one a being 1, and n is an integer, where
• b1) from 5 to 65% by weight of the silicone component b) is composed of one or more diorganopolysiloxanes with n≦30 and only one terminal polymerizable group R1, and
• b2) from 35 to 95% by weight of the silicone component b) is composed of one or more diorganopolysiloxanes with n≧55 and with one or two terminal polymerizable groups R1.