Process for producing molded article of continuous length
AssigneeToyoda Gosei Co., Ltd.
InventorsJunji Koizumi, Haruyasu Mizutani, Koichi Ogiso, Atsushi Goto
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Abstract
A process for dimensionally stabilizing an article molded from a synthetic resin material, such as PVC. The molded article is subjected to a first cooling treatment to cool the article at a temperature lower than the glass transition temperature Tg of the synthetic resin followed by a heating treatment at a temperature higher than the glass transition temperature Tg and then is subjected to a second cooling treatment again at a temperature lower than the glass transition temperature Tg. Following such treatment steps, the molded article, such as side molding for automobiles, have less variation in dimensions and less shrinkage after molding in use.
Claims12
A process for producing dimensionally stable injection molded articles from synthetic resins, comprising the steps of:
- injection molding an article of a synthetic resin material having a glass transition temperature Tg;
- removing the article from a mold while maintaining the temperature of the article above Tg;
- subjecting the molded article, immediately after molding, to a first cooling treatment prior to the article reaching Tg and cooling the article to a temperature lower than Tg;
- subjecting the cooled article to a heating treatment and heating the article to a temperature higher than Tg;
- and
- subsequently subjecting the article to a second cooling treatment and cooling the article to a temperature lower than Tg so that the injection molded articles possess less dimensional and shrinkage variation in use after molding.
Dependencies are inferred from the claim text.