| 摘要 |
<p>Disclosed is a lead-free optical glass for mold press molding which has characteristics required for optical glasses for mold press molding, especially a refractive index (nd) of 1.57-1.62 and an Abbe number (?d) of not less than 55, while being excellent in weather resistance. The lead-free optical glass for mold press molding is characterized by having a composition containing, in mass%, 41-56% of SiO<SUB>2</SUB>, 1.5-5% of Al<SUB>2</SUB>O<SUB>3</SUB>, 7-16% of B<SUB>2</SUB>O<SUB>3</SUB>, 0.1-10% of CaO, 0-10% of BaO, 0-10% of SrO, 0-5% of ZnO, 1-10% of Li<SUB>2</SUB>O, 0-5% of Na<SUB>2</SUB>O and 5-15% of La<SUB>2</SUB>O<SUB>3</SUB>. Preferably, the composition of the optical glass further satisfies the following conditions: MgO + CaO + BaO + SrO is 10-20%, Li<SUB>2</SUB>O + Na<SUB>2</SUB>O + K<SUB>2</SUB>O is 5-12% and 3.2 = SiO<SUB>2</SUB>/La<SUB>2</SUB>O<SUB>3</SUB> = 15.0.</p> |
