Asahi-dow Limited

Kaoru Toyouchi

Akio Yasuike

Hiroshi Kataoka

Susumu Imai

Takehiro Shibuya

Foamable synthetic resin materials are plastified and injected into a mold cavity in an amount less than the volume of mold cavity and a body of gas under pressure is charged in the mold cavity in such manner that it is enclosed by said resin materials. When the injected resin materials sets at least at its outer surface layer, the gas is discharged out of the mold cavity so that the foamable resin materials can be expanded in the hollow portion formed by the pressure of the charged gas. Said foamable resin materials may be surrounded by unfoamable resin materials in the mold cavity.

Method for producing foamed moldings from synthetic resin materials

A first thermoplastic resin for forming the shell of an article is charged into the front portion of an injection cylinder and a second thermoplastic resin for forming the core of the article is charged into the rear portion of the injection cylinder. Both resins are substantially separated, being in contact only a central area of the cross-sectional plane of the injection cylinder. These thermoplastic resins are injected in a mass into a mold cavity with the second resin enveloped by the first resin, and finally solidified in the mold cavity resulting in a molded article having sandwich construction. Various sandwich articles can be obtained easily by means of a single injection molding machine. The process also allows repeated injection operations without exposure of the core material on the surface of the molded article.

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Yokohama, Japan

Kaoru Toyouchi