Process for making a corrugation-free foam

摘要

A method for extruding a corrugation-free polystyrene foam with up to 100% carbon dioxide as the blowing agent by extruding the extrudate through an annular die opening so that it contacts a choke ring inner surface. A foam made with the apparatus according to the invention will have no visible corrugations and an average cell size of less than 0.35 mm.