MOLD FOR INJECTION MOLDING, METHOD FOR MANUFACTURING OPTICAL RECORDING MEDIUM, AND OPTICAL RECORDING MEDIUM

摘要

PROBLEM TO BE SOLVED: To manufacture an optical recording medium which has a uniform maximum shearing stress distribution in a substrate and in which a change in one circumference of a double refractive index is reduced such as, for example, a card type CD. SOLUTION: A mold for injection molding manufactures the card type CD. The mold comprises a fixed mirror 11 and a movable mirror 16 oppositely arranged via a predetermined distance so as to partition a space 15 for molding the substrate having a major axis and a minor axis. The mold further comprises a sprue bush 17 arranged at a center of the mirror 11 so that a tip of a resin flow inlet 17a is opposed to the center of the space 15. The mold also comprises a gate cutting punch 20 arranged movably in a rotating axial direction of the substrate at the mirror 16 side so that the tip is opposed to that of the bush 17. The mold also comprises a cylindrical gate 18 formed between the space 15 side end of the bush 17 and the tip of the punch 20 in such a manner that a thickness of the gate 18 in the major axis direction of the substrate is thicker than that of the substrate in the minor axis direction.