| abstract |
An open-cell polystyrene resin foam having an organic volatile content lower than 100 ppm. It is suitable for use as a core material for soundproofing materials or vacuum heat insulation materials. The open-cell foam can be produced by melt-kneading a polystyrene resin having an organic volatile content of 100 ppm or higher in an extruder together with water to cause the organic volatiles to undergo azeotropy, sucking up the resultant vapor through the vent, injecting a foaming agent, kneading the resultant mixture, and then extruding the mixture at a low pressure to foam it. |