Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
244 words
An essentially haze-free photochromic glass which, in a thickness of about 2 mm, will exhibit the following photochromic properties when measured by solar simulator: (a) over the range of about 0°-40° C. will darken to a luminous transmittance in the presence of actinic radiation of between about 40-60%; (b) over the range of about 0°-40° C. the difference in darkened luminous transmittance will be less than 15 percentage units of transmittance; and (c) over the range of about 25°-40° C. will fade at least 30 percentage units of transmittance after five minutes' removal from the actinic radiation; said glass having a composition suitable for refractive index adjustment and capable of being chemically strengthened without substantial loss of photochromic properties consisting essentially, expressed in terms of weight percent on the oxide basis, with the levels of Ag, Cu 2 O, Cl, and Br representing values as analyzed in the glass, of: ______________________________________
Li.sub.2 O 0-2.5 P.sub.2 O.sub.5
0-25
Na.sub.2 O 0-9 SiO.sub.2
20-65
K.sub.2 O 0-17 Ag 0.115-0.145
Cs.sub.2 O 0-6 Br 0.11-0.155
Li.sub.2 O + Na.sub.2 O + K.sub.2 O + Cs.sub.2 O
8-20
B.sub.2 O.sub.3 14-23 Cu.sub.2 O
0.007-0.011
Al.sub.2 O.sub.3 5-25 Cl 0.1-0.15
______________________________________ and wherein the molar ratio alkali metal oxide:B 2 O 3 ranges between about 0.55-0.85, the weight ratio Ag:(Cl+Br) ranges between about 0.65-0.95, and the sum of Ag+Br is at least 0.26%, when the Br content is 0.11%, and at least 0.25% when the Ag content is 0.115%.
Claim 2
Dependent Claim
244 words
An essentially haze-free photochromic glass which, in a thickness of about 2 mm, will exhibit the following photochromic properties when measured by solar simulator: (a) over the range of about 0°-40° C. will darken to a luminous transmittance in the presence of actinic radiation of between about 40-60%; (b) over the range of about 0°-40° C. the difference in darkened luminous transmittance will be less than 15 percentage units of transmittance; and (c) over the range of about 25°-40° C. will fade at least 30 percentage units of transmittance after five minutes' removal from the actinic radiation; said glass having a composition suitable for refractive index adjustment and capable of being chemically strengthened without substantial loss of photochromic properties consisting essentially, expressed in terms of weight percent on the oxide basis, with the levels of Ag, Cu 2 O, Cl, and Br representing values as analyzed in the glass, of: ______________________________________
Li.sub.2 O 0-2.5 P.sub.2 O.sub.5
0-25
Na.sub.2 O 0-9 SiO.sub.2
20-65
K.sub.2 O 0-17 Ag 0.115-0.145
Cs.sub.2 O 0-6 Br 0.11-0.155
Li.sub.2 O + Na.sub.2 O + K.sub.2 O + Cs.sub.2 O
8-20
B.sub.2 O.sub.3 14-23 Cu.sub.2 O
0.007-0.011
Al.sub.2 O.sub.3 5-25 Cl 0.1-0.15
______________________________________ and wherein the molar ratio alkali metal oxide:B 2 O 3 ranges between about 0.55-0.85, the weight ratio Ag:(Cl+Br) ranges between about 0.65-0.95, and the sum of Ag+Br is at least 0.26%, when the Br content is 0.11%, and at least 0.25% when the Ag content is 0.115%.
Claim 3
Dependent Claim
112 words
A photochromic glass according to claim 1 wherein to said composition are added up to 10% by weight total of the following extraneous components in the indicated proportions of up to 6% ZrO 2 , up to 3% TiO 2 , up to 0.5% PbO, up to 7% BaO, up to 4% CaO, up to 3% MgO, up to 6% Nb 2 O 5 , up to 4% La 2 O 3 , up to 0.25% As 2 O 3 and/or Sb 2 O 3 , and up to 2% F; and up to 1% total of transition metal oxides and up to 5% total of rare earth metal oxides as colorants.
Claim 4
Dependent Claim
44 words
A photochromic glass according to claim 2 having the following approximate composition: ______________________________________
SiO.sub.2
56.2 TiO.sub.2
2.3
B.sub.2 O.sub.3
18.2 ZrO.sub.2
5.0
Al.sub.2 O.sub.3
6.2 Ag 0.132
Li.sub.2 O
1.8 Cu.sub.2 O
0.007
Na.sub.2 O
4.1 Cl 0.107
K.sub.2 O
5.7 Br 0.124.
______________________________________