Process for producing expanded article of thermoplastic resin

Abstract

A process for producing an expanded article of a thermoplastic resin by extruding and expanding a foamable resin using an extruder equipped, on a resin channel in a die, with a nozzle having a number of apertures, which comprises flowing a resin mixture stream through an expansion zone while maintaining the resin mixture at a temperature above the melting point thereof, dividing the resin mixture stream into a plurality of separate streams, exiting these streams from the extrusion zone directly into a confined zone, thereby forming a plurality of soft expanded resin strands corresponding in number to the number of strands, bringing the strands into surface contact with each other to fuse and bond them together to form a bonded expanded resin mass while simultaneously removing gases generated in the course of extrusion and expansion, passing the bonded mass into an unconfined zone to permit the mass to further expand while still in a softened condition, passing the further expanded mass into a confined receiving zone of a smaller cross-sectional area than the further expanded mass, and cooling the mass to form an expanded article.