The invention relates to a polymer mixture which comprises the following constituents: Ai) a graft copolymer built up from a rubber-like graft base consisting substantially of a butadiene rubber, on which one or more vinylaromatic monomeric compounds and one or more unsaturated nitrile monomeric compounds have been grafted or Aii) a mixture of Ai and an aromatic polycarbonate, and B) a copolyether ester block copolymer having a polyether block which is derived from an ethylene-oxide-capped poly-(propylene oxide)glycol, having an ethylene oxide content of 15-35% by weight and a number-averaged molecular weight of 1,500-3,000.