| 摘要 |
PURPOSE:To facilitate processing of a mold and to make the cost low and to reduce the manufacturing cost of a press lens by forming the mold for press- molding a glass lens by SiO2-Al2O3-ZnO-MgO glass having specified composition. CONSTITUTION:The following glass is prepared which has composition consisting of by weight 51-64% SiO2, 10-19% Al2O3, 2-15% ZnO, 2-14% MgO and 0-9% B2O3. A mold for press-molding a glass lens is manufactured by using this glass. The obtained mold for press-molding has about (35-55)X10<-7>/ deg.C low coefficient of thermal expansion and can be endured to rapid heating and quenching as the mold. The above-mentioned glass is high in surface hardness and strength and also excellent in workability and can be easily worked in the mold having optical specular surface.
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