Glass for spectacle lens

Abstract

Abstract PURPOSE: To provide the titled thin lightweight glass contg. SiO 2 , B 2 O 3 , Na 2 O, K 2 O, Li 2 O, TiO 2 , etc. in a specified weight ratio, having a high refractive index and low specific gravity, and covering a low diopter region having a great demand. CONSTITUTION: Starting materials such as silica powder, aluminum hydroxide, titanium oxide, borax, potassium carbonate and magnesium carbonate are blended so as to prepare a composition consisting of, by weight 56W67% SiO 2 , 0W7% B 2 O 3 , 0W5% AlO 3 , 0W11% Na 2 O, 0W10% K 2 O, 0W7% Li 2 O (11W18% Na 2 O+K 2 O+ Li 2 O), 13W19% TiO 2 , 0W4% MgO+CaO+SrO+ZnO and 0W2% La 2 O 3 +ZrO 2 + Nb 2 O 3 , and the blend is heated to a high temp. to obtain the titled glass. This glass has ≥1.59 refractive index, ≥36 Abbe's number and ≤2.6 specific gravity. COPYRIGHT: (C)1981,JPO&Japio

Inventors

• 👤 Kunio Takeuchi
• 👤 Toshiharu Yamashita

Bibliographic Details