WATER EXPANDED POLYSTYRENE PARTICLES

摘要

The invention relates to a process for the preparation of expanded polystyrene particles in which polystyrene beads containing water as the sole expanding agent are expanded. The process involves the following stages:A) the polystyrene beads are pre-expanded at temperatures above 100° C.,B) the pre-expanded particles are dried in dry air at temperatures between 20° and 95° C. over a period of from 1 to 10 hours,C) the dried expanded particles are further expanded with steam at temperatures ranging from 100° to 140° C., andD) the stages b and c are repeated as often as is necessary to achieve the desired bulk density.