METHOD OF PRODUCTION OF AN OBJECT MADE OF A THERMOPLASTIC POLYMER ADMIXED WITH AT LEAST ONE GAS AT THE SUPERCRITICAL STATE

摘要

Method of production of an object made of a thermoplastic polymer admixed with at least one gat at the supercritical state, with a hot block (3) provided with hot mixing channels (4) having injectors (6-6 '-6 "-...) connected to a control unit (12), in turn connected to a gas tank (5); each injection nozzle (8-8'), located downstream of the hot mixing channels (4), having a third shutter (9-9') adapted to introduce a mixture of thermoplastic polymer and supercritical gas inside the interspace (13) of an injection-compression mold (20); said method consisting of: (A) extrusion of the polymer from the first shutter (2) of the feed duct (1) into the hot block (3); with the mold (20) in closed configuration; (B) injection of the supercritical gas from the injectors (6-6 '-6"-...) of the hot mixing channels (4) while the mold (20) is still in closed configuration; (C) distribution of the mixture to the injection nozzles (8-8'); (D) injection of the mixture inside the interspace (13) of the mold (20) while still closed configuration; (E) cooling of the mixture; opening of the mold and extraction of the object just produced and start of a new production cycle.