INJECTION MOLDING METHOD AND INJECTED MOLDING HAVING HOLLOW

摘要

PROBLEM TO BE SOLVED: To provide an injection molding method which can restrain a surface of a hollow from smoothing and generation of a part where thickness is abnormally deformed in the hollow. SOLUTION: A first thermoplastic resin composition pellet contains 10-50vol.% of fiber filler consisting of either a glass fiber having an average fiber diameter of 3-23μm and a weight average length which is not less than 10 times the average fiber diameter and not more than a length of pellet or a carbon fiber having an average fiber diameter of 5-13μm, a weight average length which is not less than 10 times the average fiber diameter and not more than the length of the pellet, or a mixture of these. A second thermoplastic resin composition pellet contains 0-5vol.% of fiber filler. The first thermoplastic resin composition pellet and the second thermoplastic resin composition pellet are mixed at a weight ratio of 4:1 to 1:4, kneaded and plasticized so as to make a melted resin. Thereafter, the melted resin is injected into a cavity of a mold. During the injection of the melted resin or after completion of the injection, a pressure liquid is injected into the melted resin in the cavity so as to form a hollow.