Process for the preparation of polymer particles

The process of the present invention provides a process for the production of a vinyl aromatic polymer comprising a vinyl aromatic polymer comprising a) a vinyl aromatic monomer with a copolymerizable compound to produce a prepolymerisation monomer at a 20-70% conversion of the vinyl aromatic monomer, and a polar group and vinyl-containing copolymerizable compound and an emulsified water-containing prepolymerized mass; b) suspending the resulting polymerized mass in an aqueous medium and c) polymerizing the vinyl aromatic monomer in ascites-droplets to full monomer conversion. In the subject matter of the invention there are further expandable polymeric polymers based on a copolymerisable compound having from 0.001 to 5% by weight of a vinyl aromatic monomer and vinyl aromatic monomer, a polar group and a vinyl group.maznak. These granules can be used to produce a foamed product. ŕ