Process of producing polyolefin foam moldings

Abstract

A polyolefin foam article having a smooth, lustrous skin is produced by packing small pieces of polyolefin foam in the cavity formed between a male mold and a female mold of a mold assembly. One of the molds has no perforations for the passage of vapor and the other of the molds has: (1) perforations for the passage of a vapor; and (ii) at least two chambers which divide the perforations for the passage of vapor into perforations which permit the entrance of steam into the cavity and perforations which permit the exit of steam carrying entrained air present in and between the small pieces of polyolefin foam from the cavity. After compressing the small pieces of polyolefin foam in the mold cavity, the small pieces of polyolefin foam are heated by introducing steam into the chambers of the molds in such a manner that the time of introduction of steam to at least one of the chambers of the mold having perforations for the passage of vapor is subsequent to the time of introduction of steam into the other chamber or chambers thereof. In this manner, prior to heating to fuse and weld the small pieces of polyolefin foam steam is at least once passed therethrough to entrain and remove air present in and between the small pieces of polyolefin foam.