PREPARATION OF BEAD-FORM EXPANDABLE STYRENE POLYMERS

摘要

- 11 - O.Z. 0050/40907 Bead-form expandable styrene polymers are obtained by suspension polymerization of styrene with addition of from 1 to 10 % by weight of C3to C6-hydrocarbons as blowing agents and, if desired, customary additives, where a) the polymerization is initiated by rapidly heating the polymerization batch to from 80 to 90.degree.C within a maximum of 2 hours, b) subsequently allowing the reaction temperature to increase to from 120.degree.C to 130.degree.C by from 8 to 17.degree.C per hour, and c) the conversion is from 30 to 60 % when 100.degree.C is reached, and d) the conversion is 80 % or more when the maximum temperature is reached, and e) the batch is subsequently kept at from 100 to 130.degree.C until the residual monomer content in the polymer has dropped to less than 0.1 %.