| 摘要 |
Process and apparatus for producing a partially foamed thermoplastic polymer product in a single screw extruder by dividing an initial melt stream of the polymer into separate partial melt streams conveyed individually by the extruder to a shaping or forming die, uniformly mixing a foaming agent with at least one but not all of the separate and individually conveyed partial melt streams, and then rejoining all of said melt streams in the die in abutting core and shell layers with foaming of at least one but not all of said layers. |
