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A method of producing an extruded plastics foam of enhanced physical strength includes intimately mixing a blowing agent incorporation CO.sub.2, the major portion of which is a natural gas, in a plastics resin melt to form a homogenous resin mix, and extruding the resin mix through an exit die into

A method of producing an extruded plastics foam of enhanced physical strength includes intimately mixing a blowing agent incorporation CO.sub.2, the major portion of which is a natural gas, in a plastics resin melt to form a homogenous resin mix, and extruding the resin mix through an exit die into a region of lower pressure. At the point of extrusion out of the exit die, the temperature of the resin mix is adjusted so that it is below the critical temperature.

대표청구항

[ What is claimed is:] [1.] An extruded polystyrene foam sheet incorporating a cellular structure in which the average cell diameter is less than 0.002 inches and which i-as a density less than or equal to 4.0 lbs/ft.sup.3.

[ What is claimed is:] [1.] An extruded polystyrene foam sheet incorporating a cellular structure in which the average cell diameter is less than 0.002 inches and which i-as a density less than or equal to 4.0 lbs/ft.sup.3.