US3902909A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Phototropic material and a method for its production
Assignee: Schott AG
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Filing: 1974-09-11
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Granted: 1975-09-02
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Expires: 1994-09-11
Abstract
Abstract A phototropic glass composition which is devoid of halogen, rare earths, tungsten and molybdenum and which comprises a phase separated melt-fused glass composition containing from about 70 to 95 weight percent CdO, from about 2 to 28 weight percent B2O3, and from about 2 to 28 weight percent of SiO2. Minor proportions of certain other metal oxides, such as the oxides of Ag, Au, Bi, Cu, Hg, In, Pb, Sb, Sn or Te may also be incorporated within the glass composition.
Inventors
- 👤 Georg Gliemeroth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 08:58
CPC Classifications
C; C03; C03C; C03C10/00; C03C10/0054; C03C4/00; C03C4/04; C03C4/06; C03C4/065
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
112 words
A PHOTOTROPIC GLASS COMPOSITION PREPARED FROM A STARTING COMPOSITION COMPRISING ON A 100 WEIGHT PERCENT BASIS, FROM ABOUT 70 TO 95 WEIGHT PERCENT CDO FROM ABOUT 2 TO 28 WEIGHT PERCENT SIO2 FROM ABOUT 2 TO 28 WEIGHT PERCENT B2O3. SAID GLASS COMPOSITION HAVING BEEN PREPARED BY THE STEPS OF: A. MELT-FUSING SAID STARTING COMPOSITION AT A TEMPERATURE OF FROM ABOUT 900* TO 1300*C., B. HEAT-TREATNG SAID MELT-FUSED, SUBSTANTIALLY NON-CRYSTALLINE PRODUCT AT A TEMPERATURE OF FROM ABOUT 350* TO 1100* C. FOR A TIME OF FROM ABOUT 0.4 TO 2.5 HOURS, AND C. COOLING THE RESULTING HEAT-TREATED COMPOSITION TO AMBIET TEMPERATURE AT A RATE OF FROM ABOUT 55* TO 78*C PER HOUR.
Claim 2
Dependent Claim
112 words
A PHOTOTROPIC GLASS COMPOSITION PREPARED FROM A STARTING COMPOSITION COMPRISING ON A 100 WEIGHT PERCENT BASIS, FROM ABOUT 70 TO 95 WEIGHT PERCENT CDO FROM ABOUT 2 TO 28 WEIGHT PERCENT SIO2 FROM ABOUT 2 TO 28 WEIGHT PERCENT B2O3. SAID GLASS COMPOSITION HAVING BEEN PREPARED BY THE STEPS OF: A. MELT-FUSING SAID STARTING COMPOSITION AT A TEMPERATURE OF FROM ABOUT 900* TO 1300*C., B. HEAT-TREATNG SAID MELT-FUSED, SUBSTANTIALLY NON-CRYSTALLINE PRODUCT AT A TEMPERATURE OF FROM ABOUT 350* TO 1100* C. FOR A TIME OF FROM ABOUT 0.4 TO 2.5 HOURS, AND C. COOLING THE RESULTING HEAT-TREATED COMPOSITION TO AMBIET TEMPERATURE AT A RATE OF FROM ABOUT 55* TO 78*C PER HOUR.
Claim 3
Dependent Claim
26 words
A phototropic glass composition as defined in claim 1 wherein the weight percent of CdO in the starting composition is about 73 to 79 weight percent.
Claim 4
Dependent Claim
40 words
A phototropic glass composition as defined in claim 1 which also includes up to 5 weight percent of an oxide of a metal selected from the group consisting of Ag, Au, Bi, Cu, Hg, In, Pb, Sb, Sn and Te.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-09-01 | 1979-03-03 | 1979-09-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-01 | 1983-03-03 | 1983-09-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-01 | 1987-03-03 | 1987-09-02 | $7700.00 | Window Closed / Lapsed |