MANUFACTURE OF INJECTION MOLDED PRODUCT WITH HOLLOW STRUCTURE

摘要

PURPOSE:To inject pressurized gas smoothly into molten resin in a mold cavity by disposing a check valve at the end of a gas injection opening and heating the end of the gas injection opening by means of a heating device provided separately. CONSTITUTION:For instance, modified polyphenylene ether resin is melted up to the resin temperature and plasticized in an injection molding cylinder 3, and then injected and cast into a mold cavity 4. The end of a gas injection nozzle is heated and heat insulated by a ring heater 16, and then injection is stopped after the given several seconds after the start of injection, and simultaneously compressed nitrogen gas metered by a gas metering cylinder 8 is fed forcibly out of the pressurized gas injection nozzle by a piston (a). A check valve at the end of nozzle is operated normally and heat insulation of a gas injection opening section including the check valve is carried out sufficiently.