Patent ID: 6572800
Filing Date: 2003-06-03
Classification: B29C,C08J

Abstract:
Process for producing polystyrene foam, said process comprising:plastifying a mixture of polystyrene with nucleating agents, plasticisers and additives at a pressure and temperature respectively above atmospheric pressure and room temperature to form a melt, suddenly decompressing and cooling the melt to atmospheric pressure and room temperature, on being extruded through a final extrusion die, injecting a blowing agent designed to produce the desired foaming and only consisting of CO2 into the melt so that said blowing agent is dissolved in the melt, and also injecting a first and a second control agents into the melt, the first control agent being designed to dissolve and cool the melt and consisting of ethanol, while the second control agent is only designed to cool the melt and consists of H2O2, the injected amount of ethanol being such that it is just sufficient for achieving the highest possible dissolution of CO2 in the melt, and the injected amount of H2O2 being such that the foaming produced by ethanol is minimised.