Asahi-dow Limited

Asahi Kasei Kogyo Kabushiki Kaisha

Tsukasa Yamagishi

Seizaburo Watanabe

Akira Fujie

Eiya Sato

The present disclosure is directed to foam particles of a linear, uncrosslinked ethylenic resin which can be expansion molded by heating in its uncrosslinked state. The present disclosure is also concerned with a process for preparing foam particles of a linear uncrosslinked ethylenic resin and a process for the in-mold foam molding of said resin particles.

Preparation of foam particles of ethylenic resin and foam moldings

An expansion-molded product made from expanded cross-linked polyethylene particles each of which has an outer skin and inner cellular core, said outer skin each being fused and welded together to form an interfacial membrane whose average thickness is as thick as at least three times that of a cell membrane of the inner cellular core, is prepared by charging a lot of the particles into a mold, heating the particles therein to such an extent that the space among the particles is filled and then aging thus obtained molded product. The expanded particle each has a structure having an outer skin on an inner cellular core, the outer skin being as thick as at least three times cell membrane of the inner cellular core. The expandable particles are prepared by impregnating a foaming agent into the cross-linked polyethylene particles and heating so that the expandable particles are subjected to a step in which the foaming agent existing in the surface thereof is preferentially forced to evaporate.

Expanded cross-linked polyethylene particle, a molded product thereof

Polyolefin foam having small, uniform cell size is prepared (1) by mixing a polyolefin resin with (a) a volatile organic blowing agent and (b) from about 0.1 to about 5 weight percent, based upon the polyolefin resin weight, of a cell control agent (e.g., such as amorphous silica having a pH of from 3.5 to 4.5), said cell control agent being in the form of nonporous microspheres having an average particle size of from about 5 to about 100 m.mu. and (2) by thereafter extrusion-expanding the resultant mixture.

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Suzuka, Japan

Tsukasa Yamagishi