METHOD FOR INJECTION MOLDING AND MANUFACTURE OF SUBSTRATE FOR OPTICAL INFORMATION RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To produce a substrate of an optical disk by setting stable conditions by largely shortening a time of taking the setting of injection molding conditions in the case of manufacturing the board by injection molding. SOLUTION: The method for injection molding to manufacture a substrate of an optical disk by injecting a molten resin in a cavity formed of molding surfaces of a horizontally moving movable mold and a fixed mold opposed to the movable mold comprises the steps of initially clamping the molds in the case of injecting the resin in the cavity, obtaining a first suitable range (refer to a broken line (a)) for previously causing no transfer fault from occurring and a second suitable range for causing no mold release fault from occurring in the relationship between a holding time of an initial mold clamping and a second mold clamping force when defining the mold clamping at an initial cooling stage as the second mold clamping, and injection molding according to the holding time of the initial mold clamping and the second mold clamping force to satisfy at least both the first and second ranges.