MANUFACTURE OF POLYURETHANE LENS

摘要

PURPOSE:To enhance the heat resistance of a polyurethane lens by casting a liquid mixture prepared by adding polyisocyanate to a reaction product obtained by reacting polyol with a specific ratio of polyisocyanate in a lens manufacturing mold to polymerize the same. CONSTITUTION:A reaction product is obtained by reacting polyol with polyisocyanate in a ratio of 0.001 - 0.3 equivalent per one equivalent of polyol. Further, polyisocyanate is added to the reaction product to obtain a liquid mixture. The mixing amount of polyisocyanate is pref. set to such a range that the equivalent ratio of polyisocyanate to polyol is set to 0.5 - 3.0 in the sum amount containing the amount of polyisocyanate to be used. The liquid mixture is cast in a lens manufacturing mold and polymerized to obtain a polyurethane lens. With respect to the polymerization temp. in casting polymerization, initial temp. is pref. 5 - 40 deg.C and may be raised to 100 - 130 deg.C over 10 - 70hr.