Phototropic glass with a refractive index greater than or equal to 1.59, an abbe number greater than or equal to 44 and a density less than or equal to 3.0 g/cm3

Claim 2

A phototropic glass in which the carriers of phototropism are precipitates containing silver, halogens and optional phototropy sensitizers and which has a refractive index n d equal to or higher than 1.59, an Abbe number equal to or greater than 44 and a density equal to or less than 3.0 g/cm 3 , consisting essentially of in % by weight on an oxide basis: ______________________________________ SiO.sub.2 42-56 B.sub.2 O.sub.3 11-18 Al.sub.2 O.sub.3 0-5 sum of SiO.sub.2, B.sub.2 O.sub.3, and Al.sub.2 O.sub.3 55-75 Li.sub.2 O 3-9 Na.sub.2 O 0-7.98 K.sub.2 O 0-8.22 sum of alkali metal oxides 7-15 MgO 3-12 CaO 0-3 SrO 0-3 BaO 0-6 ZnO 0-2 sum alkali earth metal 3-12 oxides and ZnO TiO.sub.2 3.06-6.74 ZrO.sub.2 2-11 Nb.sub.2 O.sub.5 2.28-8 La.sub.2 O.sub.3 0-3 PbO 0-2 Er.sub.2 O.sub.3 0-1 ______________________________________ the total of the foregoing oxides being 100 wt. %, and in addition, phototropically effective amounts of Ag 2 O, a halogen and optional phototropy sensitizers.

Claim 3

A phototropic glass of claim 1, consisting essentially of, in % by weight on an oxide basis: ______________________________________ SiO.sub.2 42 to 56 B.sub.2 O.sub.3 11 to 18 Al.sub.2 O.sub.3 0 to 5 sum of SiO.sub.2, B.sub.2 O.sub.3, Al.sub.2 O.sub.3 : 55 to 74 Li.sub.2 O 6 to 9 Na.sub.2 O 0 to 6 K.sub.2 O 0 to 6 sum of the alkali metal 7 to 15 oxides: MgO 3 to 10 CaO 0 to 3 SrO 0 to 3 ZnO 0 to 2 sum of the alkaline earth 3 to 10 metal oxides and ZnO: TiO.sub.2 3.06 to 5 ZrO.sub.2 2 to 5 Nb.sub.2 O.sub.5 4 to 8 ______________________________________

Claim 4

A phototropic glass in which the carriers of phototropism are precipitates containing silver, halogens and optional phototropy sensitizers and which has a refractive index n d equal to or higher than 1.59, an Abbe number equal to or greater than 44 and a density equal to or less than 3.0 g/cm 3 , consisting essentially of, in % by weight on an oxide basis: ______________________________________ SiO.sub.2 40-50 B.sub.2 O.sub.3 15-18 Al.sub.2 O.sub.3 2.9-3.5 Li.sub.2 O 6.0-7.5 Na.sub.2 O 0.06-0.08 K.sub.2 O 2.7-3.0 MgO 4.0-5.0 CaO 1.5-2.0 SrO 0.0-0.1 BaO 4.5-5.5 ZnO 0.0-0.1 TiO.sub.2 4.5-5.5 ZrO.sub.2 3.0-3.5 Nb.sub.2 O.sub.5 5.0-7.0 La.sub.2 O.sub.3 0.0-0.1 PbO 0.1-0.5 Er.sub.2 O.sub.3 0.1-0.3 ______________________________________ the total of the foregoing oxides being 100 wt. %, and in addition, phototropically effective amounts of Ag 2 O, a halogen and optional phototropy sensitizers.

Claim 5

A phototropic glass in which the carriers of phototropism are precipitates containing silver, halogens and optional phototropy sensitizers and which has a refractive index n d equal to or higher than 1.59, an Abbe number equal to or greater than 44 and a density equal to or less than 3.0 g/cm 3 , consisting essentially of, in % by weight on an oxide basis: ______________________________________ SiO.sub.2 40-50 B.sub.2 O.sub.3 15-18 Al.sub.2 O.sub.3 2.9-3.5 Li.sub.2 O 6.0-7.5 Na.sub.2 O 0.06-0.08 K.sub.2 O 2.7-3.0 MgO 4.0-5.0 CaO 1.5-2.0 SrO 0.0-0.1 BaO 4.5-5.5 ZnO 0.0-0.1 TiO.sub.2 4.5-5.5 ZrO.sub.2 3.0-3.5 Nb.sub.2 O.sub.5 5.0-7.0 La.sub.2 O.sub.3 0.0-0.1 PbO 0.1-0.5 Er.sub.2 O.sub.3 0.1-0.3 ______________________________________ the total of the foregoing oxides being 100 wt. %, and in addition, phototropically effective amounts of Ag 2 O, a halogen and optional phototropy sensitizers.

Claim 6

A phototropic glass of claim 1, wherein the phototropic components are at least 0.05 wt. % of Ag 2 O, at least 0.25 wt. % of halogens, and 0 to 0.1 wt. % of copper oxide or an equivalent amount of another phototropy sensitizer.

Claim 7

A phototropic glass of claim 2, wherein the phototropic components are at least 0.05 wt. % of Ag 2 O, at least 0.25 wt. % of halogens, and 0 to 0.1 wt. % of copper oxide or an equivalent amount of another phototropy sensitizer.

Claim 8

A phototropic glass of claim 1, which is doped with an amount of a noble metal effective for achieving brown coloration when the phototropic glass is exposed to actinic radiation.

Claim 9

A phototropic glass of claim 1, whose carrier of the phototropism, in addition to the basic glass composition, consists essentially of: ______________________________________ Ag.sub.2 O at least 0.05% by weight, bromine at least 0.09% by weight, chlorine at least 0.09% by weight, and copper oxide at least 0.003% by weight. ______________________________________

Claim 10

A phototropic glass of claim 2, whose carrier of the phototropism, in addition to the basic glass composition, consists essentially of: ______________________________________ Ag.sub.2 O at least 0.05% by weight, bromine at least 0.09% by weight, chlorine at least 0.09% by weight, and copper oxide at least 0.003% by weight. ______________________________________

Claim 11

A phototropic glass of claim 4, whose carrier of the phototropism, in addition to the basic glass composition, consists essentially of: ______________________________________ Ag.sub.2 O at least 0.05% by weight, bromine at least 0.09% by weight, chlorine at least 0.09% by weight, and copper oxide at least 0.003% by weight. ______________________________________

Claim 12

A phototropic glass of claim 2, which is doped with an amount up to 2% by weight of a coloring oxide effective to color the glass in the unirradiated state.

Claim 13

A spectacle lens consisting essentially of the phototropic glass of claim 1.

Claim 14

A spectacle lens consisting essentially of the phototropic glass of claim 2.

Claim 15

A spectacle lens consisting essentially of the phototropic glass of claim 3.

Claim 16

A spectacle lens consisting essentially of the phototropic glass of claim 4.

Claim 17

A phototropic glass of claim 1, consisting essentially of the following composition: ______________________________________ SiO.sub.2 about 45.03 B.sub.2 O.sub.3 about 16.87 Na.sub.2 O about 0.07 K.sub.2 O about 2.95 Li.sub.2 O about 6.67 CaO about 1.59 MgO about 4.57 ZnO about -- BaO about 5.0 Al.sub.2 O.sub.3 about 3.21 TiO.sub.2 about 4.82 ZrO.sub.2 about 3.10 Nb.sub.2 O.sub.5 about 6.04 La.sub.2 O.sub.3 about -- PbO about 0.35 Er.sub.2 O.sub.3 about 0.19 Ag.sub.2 O about 0.19 CuO about 0.050 Cl about 1.69 Br about 0.25 [PbO about 0.35 ErO about 0.19] ______________________________________

Claim 18

A phototropic glass of claim 1, consisting essentially of the following composition: ______________________________________ SiO.sub.2 about 45.97 B.sub.2 O.sub.3 about 16.73 Na.sub.2 O.sub.[3] about 0.13 K.sub.2 O about 2.62 Li.sub.2 O about 6.57 CaO about 1.54 MgO about 4.05 ZnO about -- BaO about 5.10 Al.sub.2 O.sub.3 about 3.06 TiO.sub.2 about 4.80 ZrO.sub.2 about 3.01 Nb.sub.2 O.sub.5 about 5.86 La.sub.2 O.sub.3 about -- PbO about 0.27 Er.sub.2 O.sub.3 about 0.21 Ag.sub.2 O about 0.13 CuO about 0.046 Cl about 1.18 Br about 0.18 [PbO about 0.27 Er.sub.2 O.sub.3 about 0.21] ______________________________________

Claim 19

A spectacle lens consisting essentially of the phototropic glass of claim 15.

Claim 20

A spectacle lens consisting essentially of the phototropic glass of claim 16.