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US4088501A Expired / Lapsed US ⏱️ 0.0 years remaining

Photochromic alumino-phosphate glasses

Assignee: Pilkington Group Ltd
•
Filing: 1977-01-31
•
Granted: 1978-05-09
•
Expires: 1997-01-31
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Abstract

Abstract Fast-response photochromic boron-free aluminophosphate glasses which have silver halide crystals dispersed throughout the glass comprise, in weight percentages: ______________________________________ SiO 2 10 to 17% Al 2 O 3 20 to 29% P 2 O 5 30 to 40% R 2 O 8.5 to 17% R'O 4 to 18% ______________________________________ Where R 2 O represents Na 2 O and/or K 2 O; R'O represents CaO and/or BaO, the CaO content being at least 4% if BaO is absent and being from 0 to 7% if BaO is present, while the BaO content is from 0 to 18%; the total of SiO 2 + Al 2 O 3 + P 2 O 5 amounting to not less than 69% by weight of the glass. Preferably the total of SiO 2 + P 2 O 5 + Al 2 O 3 is not less than 72% by weight of the glass. The silver content of the glass, expressed as Ag 2 O, is preferably not less than 0.05%. Refractive index n D can be corrected to the standard ophthalmic value of 1.523 by additions of TiO 2 , ZrO 2 and/or PbO.

Inventors

  • 👤 Edric Ellis
  • 👤 Richard Gelder
  • 👤 Allan Hale

Bibliographic Details

Application Number —
Jurisdiction US
Data Source google_patents
Last Synchronized 2026-11-09 14:49
CPC Classifications
C; C03; C03C; C03C4/00; C03C4/04; C03C4/06; C03C3/00; C03C3/04; C03C3/062

Claims Analysis

Total Claims: 9
Claim 1
Independent Claim 159 words
A photochromic boron-free alumino-phosphate glass having silver halide crystals dispersed throughout the glass, the glass comprising, in weight percentages: ______________________________________ SiO.sub.2 10 to 17% Al.sub.2 O.sub.3 20 to 29% P.sub.2 O.sub.5 30 to 40% R.sub.2 O 8.5 to 17% R'O 4 to 18% ______________________________________ where R 2 O represents Na 2 O and/or K 2 O; R'O represents CaO and/or BaO, the CaO content being at least 4% if BaO is absent and being from 0 to 7% if BaO is present, while the BaO content is from 0 to 18%; the total of SiO 2 + Al 2 O 3 + P 2 O 5 amounting to not less than 69% by weight of the glass; and, in weight percentages, expressed as quantities over and above the 100% total of all other components: ______________________________________ Ag.sub.2 O 0.07 to 0.35% CuO 0.005 to 1.0% Cl + Br 0.4 to 2.0% Cl 0 to 1.0% Br 0.20 to 1.0%. ______________________________________
Claim 2
Dependent Claim 159 words
A photochromic boron-free alumino-phosphate glass having silver halide crystals dispersed throughout the glass, the glass comprising, in weight percentages: ______________________________________ SiO.sub.2 10 to 17% Al.sub.2 O.sub.3 20 to 29% P.sub.2 O.sub.5 30 to 40% R.sub.2 O 8.5 to 17% R'O 4 to 18% ______________________________________ where R 2 O represents Na 2 O and/or K 2 O; R'O represents CaO and/or BaO, the CaO content being at least 4% if BaO is absent and being from 0 to 7% if BaO is present, while the BaO content is from 0 to 18%; the total of SiO 2 + Al 2 O 3 + P 2 O 5 amounting to not less than 69% by weight of the glass; and, in weight percentages, expressed as quantities over and above the 100% total of all other components: ______________________________________ Ag.sub.2 O 0.07 to 0.35% CuO 0.005 to 1.0% Cl + Br 0.4 to 2.0% Cl 0 to 1.0% Br 0.20 to 1.0%. ______________________________________
Claim 3
Dependent Claim 32 words
A glass according to claim 1, wherein the total of SiO 2 + P 2 O 5 + Al 2 O 3 is not less than 72% by weight of the glass.
Claim 4
Dependent Claim 35 words
A glass according to claim 1, further comprising TiO 2 in an amount of up to 6% by weight, the amount of TiO 2 constituting part of the said 100% total of all other components.
Claim 5
Dependent Claim 17 words
A glass according to claim 3, wherein the TiO 2 content does not exceed 3% by weight.
Claim 6
Dependent Claim 35 words
A glass according to claim 1, further comprising ZrO 2 in an amount of up to 10% by weight, the amount of ZrO 2 constituting part of the said 100% total of all other components.
Claim 7
Dependent Claim 17 words
A glass according to claim 5, wherein the ZrO 2 content does not exceed 7% by weight.
Claim 8
Dependent Claim 33 words
A glass according to claim 1, further comprising PbO in an amount of up to 4% by weight, the amount of PbO constituting part of the said 100% total of all other components.
Claim 9
Dependent Claim 16 words
A glass according to claim 7, wherein the PbO content does not exceed 1.5% by weight.

References Cited (Backward Citations)

US3615761A Cited
US3876436A Cited

USPTO Annuity & Maintenance Windows

Annuity Stage Window Opens Payment Deadline Surcharge Period Until Estimated Fee Status
3.5 Years (Year 4) 1981-05-08 1981-11-07 1982-05-09 $2000.00 Window Closed / Lapsed
7.5 Years (Year 8) 1985-05-08 1985-11-07 1986-05-09 $3760.00 Window Closed / Lapsed
11.5 Years (Year 12) 1989-05-08 1989-11-07 1990-05-09 $7700.00 Window Closed / Lapsed

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