The invention relates to a composition for production of a thermoplastic moulding compound, wherein the composition comprises or consists of the following constituents, A) at least one polymer selected from the group consisting of aromatic polycarbonate, aromatic polyester carbonate and aromatic polyester, B) polymer free of epoxy groups, consisting of B.1) rubber-modified vinyl (co)polymer prepared by the emulsion polymerization method and B.2) optionally, a rubber-free vinyl (co)polymer, C) a block or graft polymer comprising structural elements deriving from styrene and at least one epoxy-comprising vinyl monomer, D) one or more further additives, and to a process for producing a moulding compound from the composition, to the moulding compound itself, to the use of the composition or the moulding compound for production of mouldings, and to the mouldings themselves.