Process for foaming flame retardant polystyrene and polystyrene shaped articles

摘要

Polystyrene melts treated with flameproofing agents and nucleating agents are foamed by addition of alkanes, such as propane, butane or propane/butane mixtures, as blowing agents, such that the flame retardant properties of the polystyrene foams are achieved after a very short storage time, or at the latest after storage for three weeks at room temperature. Even after a storage time of one week, sufficient blowing agent is still present in the closed-cell pores of the polystyrene foams to be able to undertake adequate post-expansion of the foams with a foaming factor of 1.8 to 2.0.