Process for preparing rubber-modified moulding compounds

A process for preparing rubber-modified molding compositions, which comprises

• a1) anionic polymerization of a mixture (A) comprising acrylate derivatives or methacrylate derivatives or acrylate derivatives and methacrylate derivatives and a solvent, and comprising olefinically unsaturated compounds which are not acrylate derivatives or methacrylate derivatives, to give a (co)polymer comprising acrylate monomers whose homopolymers have a glass transition temperature below 0° C., or
• a2) sequential anionic polymerization of acrylate derivatives or methacrylate derivatives or acrylate derivatives and methacrylate derivatives in the presence of a solvent which comprises olefinically unsaturated compounds, to give block copolymers having at least one block made from monomers whose homopolymers have a glass transition temperature below 0° C., and
• b) subjecting the reaction mixture obtained in a1) or a2) or a1) and a2) to a free-radical-initiated polymerization, optionally after adding further unsaturated compounds.