Mold for plastic lens, method for manufacturing plastic lens, and plastic lens for eyeglasses

A mold for a plastic lens, into a cavity of which molten raw material resin can be injected and filled so as to mold integrally with an insert member in the cavity a plastic lens having a predetermined shape, the mold comprising:

• a pair of halved molds forming the cavity therebetween;
• a gate, one end of which opens to the cavity and through which the molten raw material can be injected into the cavity;
• and
• the insert member, which is arranged on a molding surface on one of the halved molds, wherein
• a notch, which has a semicircular recess shape and is engaged with a positioning tab formed at a periphery of the insert member, is engraved on a parting surface on one of the halved molds so as to overlap with a width of the gate,
• the positioning tab of the insert member is engaged with the notch to position the insert member, and
• a protrusion to define an opening shape of the gate communicating with the cavity is formed on the parting surface of the one halved mold, the notch (i) being a recessed portion formed at a foot of the protrusion so as to open toward the cavity and receive the positioning tab and (ii) having a wall extending in a height direction of the protrusion so as to contact a tip end of the positioning tab, and a height of the protrusion not permitting the positioning tab received in the notch to protrude into the gate.