Homogeneous composition of expandable styrene polymer, process for preparing said composition, process for pre-expansion or prefoaming, expanded beads and expanded moulded parts

摘要

A homogeneous composition of an expandable styrene polymer in the form of beads comprising (a) 100 parts by weight of a styrene polymer having a weight-average molecular mass of 150 000 to 300 000 and a residual monomer content of less than 2 000 ppm, (b) from 2 to 9 parts by weight of at least one blowing agent comprising n-pentane, (c) from 0.1 to less than 1.0 part by weight of a petroleum wax comprising a mixture of C18 to C80 alkanes, and (d) from 0 to 1.0 part by weight of a nucleating agent chosen from synthetic Fisher-Tropsch or polyolefin waxes. It is described a process for its preparation comprising an aqueous suspension polymerization, an expanded beads and an expanded moulded parts obtained from the composition of the expandable styrene polymer.