PROCESS FOR THE PREPARATION OF EXPANDABLE VINYL AROMATIC POLYMERS WITH A REDUCED THERMAL CONDUCTIVITY BY POLYMERIZATION IN SUSPENSION

摘要

Process for the preparation of beads of expandable vinyl aromatic polymers by polymerization in aqueous suspension which comprises:
a. polymerizing at least one vinyl aromatic monomer in aqueous suspension in the presence of a peroxide initiator system active at a temperature higher than 80°C and an expanding agent, optionally in the presence of:
an amine having the general formula
€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒ€ƒR1-N-R2R3€ƒ€ƒ€ƒ€ƒ€ƒ(I)
and
a flame-retardant system comprising a brominated additive with a bromine content higher than 30% by weight;
b. cooling the aqueous suspension, at the end of the polymerization, with a cooling rate of 0.2-0.3°C/min.