초록 ▼

A method and apparatus for continually metering a gaseous blowing agent in an accurate and precise manner into a molten resin charge, such as polystyrene. This is accomplished by a free piston-cylinder combination which is actuated by the gas blowing agent and which continually meters discrete unifo

A method and apparatus for continually metering a gaseous blowing agent in an accurate and precise manner into a molten resin charge, such as polystyrene. This is accomplished by a free piston-cylinder combination which is actuated by the gas blowing agent and which continually meters discrete uniform volumetric charges of the gaseous agent into the molten resin. The blowing agent is uniformly distributed throughout the resin charge and extruded into a region of lower pressure to yield a foamed structure.

대표청구항 ▼

The method of preparing a thermoplastic resin foam structure comprising: introducing, to a molten resin charge under pressure, a gas blowing agent from a supply gas source of comparatively higher pressure, said introducing being by means of discrete uniform volumetric charges of gas into said resin,

The method of preparing a thermoplastic resin foam structure comprising: introducing, to a molten resin charge under pressure, a gas blowing agent from a supply gas source of comparatively higher pressure, said introducing being by means of discrete uniform volumetric charges of gas into said resin, wherein said discrete volumetric charges are introduced by means of a free piston-cylinder combination given motive power by said supply gas source; uniformly distributing said blowing agent throughout said resin charge; and extruding the combination into a region of lower pressure to yield a foam structure.