Patent ID: 6616868
Filing Date: 2003-09-09
Classification: B29C,B29L,Y10S

Abstract:
A method of producing an optically molded product of a thermoplastic resin by injection compression molding, the method comprising the steps:(1) expanding the volume of a cavity more than the volume of the optically molded product of interest; (2) injecting a molten thermoplastic resin into the cavity through an injection cylinder; (3) compressing the expanded cavity to a prescribed thickness of a center portion of the molded product or a thickness 200 &mgr;m smaller than the prescribed thickness; (4) changing resin pressure in the injection cylinder and compression pressure in the cavity in limits that the change width does not exceed 100 &mgr;m from the prescribed thickness of center portion of the molded product to achieve the prescribed thickness of the molded product in the end; (5) keeping the molten thermoplastic resin in the cavity until the molded product of interest is formed; and (6) taking out the obtained molded product from the cavity.