| 摘要 |
PURPOSE:To shorten the curing time and prevent the deformation and internal strain of a lens from developing by a method wherein infrared heater or far infrared heater is used as the heat source for curing thermosetting resin. CONSTITUTION:A deformation- and internal strain-free lens can be obtained in a short time by using infrared rays or far infrared rays excellent in deep penetrability as the heat source for curing thermosetting resin in order to reduce the temperature difference between the surface and the interior of the lens at setting. For example, 100g of hexamethylene diisocyanate and 54g of 1,4- butanediol are poured in a glass mold. An infrared heater is used as heat source in order to raise the temperature at the center of the lens from 20 deg. to 80 deg.C in one hour and, after that, the temperature being keep at constant temperature of 80 deg.C for thirty minutes for setting by changing the power and distance of the heat source. The thus-obtained lens shows no internal strain when observed with a polarimeter. |
