METHOD FOR PRODUCING LIGHTWEIGHT THERMOPLASTIC RESIN MOLDING

PROBLEM TO BE SOLVED: To develop a method for producing a lightweight thermoplastic resin molding in which a mold cavity shape is reproduced clearly even in an end surface and which is excellent in appearance not only in the surface and back of the molding but also in the end surface. SOLUTION: In the method in which a molten thermoplastic resin to be a base material part is supplied between male and female molds of a pair of a mold, after the resin is packed in a mold cavity, part or the whole of the mold is opened in the thickness direction of the molding, and the molding is cooled with a cavity clearance kept to be a final molding thickness, the molding is produced through a process (process 1) in which a molten thermoplastic resin 1 is supplied/packed into a mold cavity, a process (process 2) in which part or the whole of the mold is opened in the thickness direction of the mold to be the final thickness of the molding, a process (process 3) in which the molding is cooled while the cavity clearance is kept to be the final thickness of the molding, a process (process 4) in which a molten thermoplastic resin 2 is supplied/packed into the space between the molding surface of the mold and the molding, and a process (process 5) in which the resin 2 is cooled and integrated with the molding of the resin 1.