Patent ID: 8536279

Claim:
A block copolymer or graft copolymer, comprising a) at least one block S comprising from 95 to 100% by weight of vinylaromatic monomers and from 0 to 5% by weight of dienes, and b) at least one copolymer block (S/B) A comprising from 63 to 80% by weight of vinylaromatic monomers and from 20 to 37% by weight of dienes, with a glass transition temperature Tg A in the range from 5 to 30° C., and c) optionally at least one copolymer block (S/B) B comprising from 20 to 60% by weight of vinylaromatic monomers and from 40 to 80% by weight of dienes, with a glass transition temperature Tg B in the range from 0 to −110° C., wherein the proportion by weight of the entirety of all of the blocks S is in the range from 50 to 70% by weight, based on the block copolymer or graft copolymer and the proportion by weight of the entirety of all of the blocks (S/B) A and (S/B) B is in the range from 30 to 50% by weight, based in each case on the block copolymer or graft copolymer; wherein if component c) is present the block copolymer has a linear structure having the block sequence S 1 -(S/B) A -S 2 -(S/B) B -S 3 and if component c) is not present the block copolymer has a linear structure having the block sequence S 1 -(S/B) A -S 2 -(S/B) A -S 3 where each of S 1 , S 2 , and S 3 is a block S; and wherein the proportion by weight of blocks S 1 and S 2 , based on the block copolymer, is from 50% to 67% by weight and the total weight-average molar mass M w of the block copolymer or graft copolymer is in the range from 260,000 to 350,000 g/mol.