GLASS FOR PRESS MOLDING

摘要

A glass for press molding, characterized in that it contains 38 to 45 wt % of SiO2, 18 to 27 wt % of B2O3, 16 to 25 wt % of Al2O3, 2 to 12 wt % of ZnO, 3 wt % or less of MgO, 3 wt % or less of CaO, 3 wt % or less of BaO, 13 to 18 wt % of Li2O, 3 wt % or less of K2O, and 2 wt % or less of Na2O, has a deformation temperature of 520°C or less, and exhibits the resistance to water of the second class or higher, as measured according to the method for measuring the chemical durability of an optical glass in Japanese Optical Glass Industrial Standard. The above glass is a novel glass material which allows the production of a glass product being excellent in chemical durability and also having high precision by means of a press molding process.