Patent ID: 7151064

Claim:
An optical glass for molding, being excellent in chemical durability and having a transformation temperature (Tg) of at most 350° C., a chemical durability represented by a weight loss in distilled water in a range of at most 0.30%, and a specific gravity (Sg) of at most 3.1, which is represented, in term of elements for making up the glass, by the following chemical composition (wt % on oxide basis, calculated from the component composition): P 2 O 5 39 to 47%, Li 2 O 2 to 9%, Na 2 O 7 to 28%, K 2 O 3 to 27%, Sum of R 2 O 17 to 41% (R: Li, Na, K), Al 2 O 3 6.5 to 30%, ZnO 0 to 22%, BaO 0 to 17%, SrO 0 to 18%, CaO 0 to 16%, MgO 0 to 14%, Sum of R′O 0 to 34% (R′: Zn, Ba, Sr, Ca, Mg), ZrO 2 0 to 1.5% and F 1.5 to 32%.