초록 ▼

A continuous foam production system is disclosed wherein a molten thermoplastic resin is mixed with volatile blowing agent at elevated pressure to form an extrusion mass. A helical screw extruder means is adapted to extrude the molten resin with volatile blowing agent into a low pressure foaming zon

A continuous foam production system is disclosed wherein a molten thermoplastic resin is mixed with volatile blowing agent at elevated pressure to form an extrusion mass. A helical screw extruder means is adapted to extrude the molten resin with volatile blowing agent into a low pressure foaming zone to form a foam sheet, tube or other shape. An improved fluid handling system includes storage means for holding at least one of a plurality of disparate volatile liquids under pressure sufficient to maintain a normally gaseous blowing agent in liquified state and cooling means for receiving a pressurized first stream of liquified thermally-gaseous blowing agent and cooling below its autogenous temperature. A pump operatively connected between the cooling means and extruder means increases pressure of the first stream higher than the elevated pressure of the extruder, where it may be combined with a pressurized stream of second liquid blowing agent. Flow control means is provided for injecting a predetermined amount of disparate liquid blowing agents from the first and second streams into the extruder means at elevated pressure to form an extrusion mass.

대표청구항 ▼

A system for producing foamable thermoplastic resin mixture comprising: extruder means for transporting resin under pressure from a feed point to a discharge point through a heating zone, fluid injection zone and mixing zone; resin supply means for introducing resin to the extruder means at the fee

A system for producing foamable thermoplastic resin mixture comprising: extruder means for transporting resin under pressure from a feed point to a discharge point through a heating zone, fluid injection zone and mixing zone; resin supply means for introducing resin to the extruder means at the feed point for melting in the heating zone; storage means for maintaining a plurality of diverse volatile liquids under the autogeneous pressure of the material, at least one of said volatile liquids being normally gaseous; fluid handling means for pressurizing said iquids from said storage means to the fluid injection zone of the extruder means; heat exchange means operatively connected between said storage means and said fluid handling means for cooling the normally-gaseous material to prevent flashing thereof during pumping; and flow metering means operatively connected with the fluid handling means for supplying predetermined amounts of the diverse volatile liquids.