Thermoplastisches Harzprodukt und seine Herstellung

摘要

A thermoplastic resin is melted in a continuous plasticator (1), supercritical carbon dioxide and/or nitrogen is added as a blowing agent, and the blowing agent and the thermoplastic resin are formed into a mutually-dissolved state. The resultant molten resin composition is cooled within the plasticator while maintaining a pressure equal to or higher than a critical pressure of the blowing agent. The thus-cooled molten resin composition is metered by an injector (7) and is filled in a mold (8). An internal pressure of the mold is lowered beyond the critical pressure of the blowing agent to produce cell nuclei, whereby the cell diameter is controlled. The blowing agent is maintained in a supercritical state up to the metering and injection step. The expanded product has, as an inner layer, an expanded portion of a fine average cell diameter and a uniform average cell population and, as a surface layer, an unexpanded portion integral with the expanded portion, and presents a good surface appearance.