Patent ID: 7341967

Claim:
A glass for press molding, comprising 38% to 45% by weight of SiO 2 , 18% to 27% by weight of B 2 O 3 , 16% to 25% by weight Al 2 O 3 , 2% to 12% by weight of ZnO, no more than 3% by weight of MgO, no more than 3% by weight of CaO, no more than 3% by weight of BaO, 13% to 18% by weight of Li 2 O, no more than 3% by weight of K 2 O, and no more than 2% by weight of Na 2 O; wherein the glass has a deformation temperature of 520° C. or lower; and the glass has a water resistance of grade 2 or higher as measured according to the Japanese Optical Glass Industrial Standard method for measuring the chemical durability of an optical glass.