Method and apparatus for preparing thermoplastic foam.

摘要

Thermoplastic foam is prepared by a continuous process comprising melt mixing thermoplastic resin; pressurizing the resin melt; introducing blowing agent; cooling and depressurizing the resultant gel; and either foaming and forming the gel to form a solid foam or forming the gel to form a foamable composition. The process temperature is maintained substantially independently of the flow rate of the resin melt and gel at below that at which substantial degredation of the resin gel occurs. The process has particular application to rubber-modified polystyrene or rubber-modified polyethylene resin foam compositions containing a fire retardant.