Patent ID: 7682531

Claim:
A method of manufacturing a plastic lens, comprising: mixing components (A) and (B), the component (A) comprising an isocyanate terminal prepolymer in a form of a reaction product of an aliphatic diisocyanate having an intramolecular cyclic structure and a diol having an average molecular weight of 300-2,500, the component (B) comprising at least one aromatic diamine denoted by a formula (I) having a structure, where in the formula (I), R 1 , R 2 and R 3 are each independently one of a methyl, ethyl and thiomethyl group; casting a mixture of said components (A) and (B) into a casting mold; and polymerizing the mixture to obtain a molded article, wherein the mixing of the following components (A) and (B) is carried out after heating said component (A) to reduce viscosity of said component (A), said casting mold has a mold for forming one side of the lens and a mold for forming the other side thereof that are positioned opposite at a prescribed interval, a circular gasket is positioned around said molds, and a cavity is formed by said molds and gasket, said gasket has a casting hole for casting the mixture of said components (A) and (B) into said cavity and a discharge hole for discharging gas and said mixture in said cavity to an exterior of the casting mold, that are positioned opposite in a diameter direction, said casting into the casting mold is carried out in a state that said casting mold is tilted from or perpendicular to a horizontal plane as well as said discharge hole is positioned at a top, and said polymerizing comprises leaving the casting mold in a low-temperature atmosphere to polymerize said mixture in the casting mold by a self heating of said mixture and leaving the casting mold in a high-temperature atmosphere to further proceed polymerization of said mixture after a temperature of the self heating reaches a maximum peak.