Process for producing beaded expansible styrene polymers with a reduced inner water content

摘要

A process is disclosed for producing beaded, expansible styrene polymers that contain: (a) polystyrene and/or styrene copolymer with at least 50 % by weight styrene incorporated by polymerization; (b) 0.001 to 0.2 % by weight, in relation to (a), of an organic tin compound; and (c) 2 to 10 % by weight, in relation to (a), of an aliphatic C3-C7-hydrocarbon and/or carbon dioxide as a blowing agent. Styrene and possibly other comonomers are polymerized in an aqueous suspension and before 50 % thereof are reacted 0.001 to 0.20 % by weight of an organic tin compound, and possibly 0.2 to 4 % by weight, in relation to the monomer weight, of an organic bromine compound, are added to the mixture; 2 to 10 % by weight of a C3-C7-hydrocarbon and/or carbon dioxide are added before, during or after polymerization as a blowing agent.