PROCESS FOR THE PREPARATION OF EXPANDABLE POLYSTYRENE BEADS

摘要

Expandable monovinylidene aromatic polymer, e.g., polystyrene, beads are prepared by a suspension polymerization process comprising polymerizing monovinylidene aromatic monomer, e.g., styrene, under suspension polymerization conditions with, based on the weight of the monomer: A. 0.05 to 0.60 percent by weight (wt%) of tricalcium phosphate, B. Greater than 0 to 0.1 wt% of calcium carbonate, C. 0.0002 to 0.005 wt% of co-stabilizer, D. 0.0001 to 0.01 wt% of a low molecular weight polyethylene wax, E. 0.4 to 0.9 wt% of a flame retardant, and F. 2 to 10 wt% of a C3-6 hydrocarbon blowing agent. The expandable beads are converted to foam having a low thermal conductivity by contacting the separated and dried expandable beads at foaming conditions with, based on the weight of the monomer: A. 0.05 to 0.65 wt% of a glyceride comprising units of fatty acids with a C8-26 chain length, and B. 0.005 to 0.30 wt% of a metal stearate.