Method of making expandable styrene-type polymer beads

Abstract

Expandable styrene-type polymer beads having a short cooling time are obtained by a method wherein styrene-type polymer beads are impregnated with a blowing agent preferably as a step separate and independent of the polymerization step or in the same suspension polymerization reactor after a substantial completion of the polymerization, in an aqueous suspension comprising styrene-type polymer beads, a blowing agent, a suspending agent, at least 0.0001% of a halide salt of a transition metal selected from the group consisting of iron, titanium, vanadium, chromium, manganese, cobalt, nickel and copper, or a mixture thereof, and at least 0.001% of glycerol mono-, di-, or tri-ester of a fatty acid having 12-30 carbon atoms or a mixture thereof, said halide being bromide, chloride or iodide, and said percentages being based on the total weight of polymer beads subjected to the impregnation, with the proviso that if said glycerol ester is a tri-ester, there must be present at least 0.0001% of a bromide salt of said transition metal or a mixture thereof.

Dependencies are inferred from the claim text.