Okamoto Industries, Inc.

Asahi Denka Kogyo Kabushiki Kaisha

Itaru Horiguchi

Akinori Watanabe

Hiroshige Kohno

Atsushi Sato

Kenji Ikeda

Toshihiro Hayashi

Osamu Tsuchiya

Satoru Hamada

Tsuguyo Ando

Yujiro Iwasaki

In charging a fluid molding material in an elastic molding die composed of a die body having an opening and a die support portion extending from the opening to the outside by pouring the molding material from the opening into time die body, the molding material in an amount of 1/5 to 3/5 of a volume of the die body is first charged, a molding material-charged portion of the die body is then crumpled or pinched, and then the entire die body is filled up with the molding material. The crumpling or pinching operation is achieved by such means as a blade shutter, pressing plates, air bags, or passing between two plates or conveyor belts, thereby charging the fluid molding material in the die body of the elastic-molding die without occurrence of air voids.

Method for charging molding material in elastic molding die

A method of manufacturing hollow molded articles having a beautiful surface at a low cost and by a simple and efficient process includes providing a hollow elastic molding die made of an elastic film and having an opening port, feeding a material to be molded of an amount smaller than the internal volume of the elastic molding die into the elastic molding die through the opening port, closing the opening port, solidifying the material to be molded while the elastic molding die is rotated to all directions, and parting the solidified hollow molded article from the elastic molding die. Arrangement for preventing the elastic molding die from being deformed while it is rotated to all directions includes holding it firm by a solid holding member conforming to the external shape thereof or by positioning it in a fluid or powdery material holding member.

Method of manufacturing hollow molded articles

A surface coating agent to be coated on the surface of an elastic molding die, which is a solvent solution of a polyurethane obtained by reacting a polyol with an aromatic polyisocyanate. The surface coating agent can be coated on the inside surface of the elastic molding die to form a coating layer, thereby obtaining a molding with surface gloss. Further, the surface coating agent can be incorporated with silicone and/or a fluorine compound to improve oil resistance of the elastic molding die, preventing the elastic molding die from being swollen by oil components of a molding material and improving durability. When a polyether type polyol is used as the polyol, water resistance of the elastic molding die can be even further improved. The surface coating agent using polycarbonatepolyol as the polyol has improved adhesion to the elastic molding die, thereby improving the durability. Further, the surface coating layer can be even more securely bonded to the surface of the elastic molding die by coating the surface coating agent after primer coating, or after acid treatment, or after acid treatment and primer coating.

Surface coating agent and surface coating method for elastic molding die

An elastic molding die is composed of an elastomer laminate film, of which the innermost layer is formed of an elastomer not containing fillers. The innermost layer elastomer is preferably an oil-resistant elastomer. Alternatively, an oil-repellent agent may be contained in the innermost layer elastomer. The outer layer may be formed of an elastomer containing fillers. Furthermore, an oil blocking layer can be provided between the inner layer and the outer layer. A master model is dipped in an elastomer solution not containing fillers, heat dried to form a gelled elastomer film, the film is coated with a coagulant, dipped again in an elastomer solution, taken out, gelation treated, and the elastomer film is peeled from the master model to obtain an elastic molding die. In another method, a once-formed hollow elastic molding die is turned inside out, pressed in with a gas to swell, the swollen die is coated with an elastomer solution not containing fillers, heat dried, and turned it again inside out.

Elastic molding die

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Ryugasaki, Japan

Itaru Horiguchi