THERMOPLASTIC RESIN FOAMED INJECTION-MOLDED BODY AND MANUFACTURE THEREOF

PROBLEM TO BE SOLVED: To make it possible to obtain a uniform and fine cell diameter even when a large-sized molded article is dealt with by a method wherein the inner layer of the molded body is made of a foamed part having a specified cell side and a specified average cell density and its skin layer having a foamed portion with a specified thickness and a non-foamed portion integral with the foamed portion. SOLUTION: In a mold 8, in which high pressure gas is filled, a molten resin composition, in which a thermoplastic resin composition and carbon dioxide and/or nitrogen are under a state compatible with each other, is injected. By quickly degassing the high pressure gas filled in the mold 8 after the injection, a quick pressure depression is developed in the mold 8. By means of this above-mentioned process, the gas impregnated in a resin becomes a supersaturated state, resulting in developing a large number of nuclei. A cell size can be controlled through the temperature of the mold 8, the internal pressure of the mold 8 and a pressure depression speed so as to obtain the cell size of 0.01-50μm and the average cell density of 10 -10 /cm . A skin layer has a non-foamed portion, in which no cell having its size of 1μm or more is present and the thickness of which is 10-1,000μm.