ANTI-LUMPING COMPOUNDS FOR USE WITH EXPANDABLE POLYSTYRENES

摘要

An anti-lumping agent for use with expandable polystyrene beads is disclosed. The expandable polystyrene beads comprise a styrene or styrene derivative polymer in combination with a blowing agent. Typical blowing agents are C3-C6 hydrocarbons, with pentane being especially preferred. The anti-lumping agents include block copolymers formed from blocks of ethylene oxide and propylene oxide. Preferably, the copolymers have a number average molecular weight of from about 4,000 to 15,000 g/mol, and a hydrophilic-lipophilic balance number of from about 16 to 29. The anti-lumping agents significantly reduce the lumping potential of the expandable polystyrene beads, especially when they are expanded to low densities of from about 12.0 - 24.0 g/l (1.5 to 0.75 lbs. per cubic foot), and more preferably to densities of from about 13.6 - 19.2 g/l (1.2 to 0.85 pcf).