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AssigneeSumitomo Chemical Company, Limited
InventorsTeruyoshi Usamoto, Kenji Miyawaki, Toshiaki Shiota, Hideki Takeuchi, Yoshio Tadokoro
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An injection molding process for forming cross-linked, foamed moldings of an ethylenic polymer by passing a molding composition comprising an ethylenic polymer/cross-linking agent/foaming agent blend through the cylinder of an injection molding machine without substantially decomposing the cross-linking agent and the foaming agent, introducing the molding composition into a molding composition holding chamber provided at the exit end of the cylinder of the injection molding machine to decompose the cross-linking agent and the foaming agent therein, and injecting the molding composition into a mold. The invention also provides apparatus for carrying out the process comprising an injection molding cylinder for conveying and plasticizing the molding composition and a molding composition holding chamber provided at the exit end of the cylinder.
A process for injection molding a cross-linked foamed ethylenic polymer article, which comprises plasticizing a molding composition comprising an ethylenic polymer, a cross-linking agent, and a foaming agent without substantially decomposing the cross-linking agent and the foaming agent, transporting said plasticized composition to a holding chamber, holding and heating said molding composition temperature and time sufficient to decompose the cross-linking agent and the foaming agent in said holding chamber while maintaining sufficient pressure on said composition to prevent foaming thereof and to thereby cross-link said ethylenic polymer to a gel percentage of less than about 40%, and then injecting said molding composition into a mold to form said article.
Dependencies are inferred from the claim text.