US4640900A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Low expansion glass
Assignee: AGC Inc
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Filing: 1984-07-27
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Granted: 1987-02-03
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Expires: 2004-07-27
Abstract
Abstract A low expansion glass comprising, all by weight, from 55 to 65% of SiO2, from 10 to 20% of Al2O3, from 2 to 10% of B2O3, from 3 to 10% of MgO, from 1 to 8% of CaO, from 2 to 10% of ZnO, from 0 to 4% of R2O where R is an alkali metal atom, and from 0 to 4% of ZrO2.
Inventors
- 👤 Yoshinori Kokubu
- 👤 Makoto Moriyasu
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 22:57
CPC Classifications
C; C03; C03C; C03C3/00; C03C3/04; C03C3/076; C03C3/089; C03C3/091; C03C3/093
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
190 words
A low expansion transparent glass substrate consisting of, all by weight, from 55 to 65% of SiO 2 , from 10 to 20% of Al 2 O 3 , from 2 to 10% of B 2 O 3 , from 3 to 10% of MgO, from 1 to 8% CaO, from 2 to 10% of ZnO, from 1 to 4% of R 2 O where R is an alkali metal atom and of which at least 1% is Na 2 O, from 0.1 to 4% of ZrO 2 , from 0 to 5% of at least one component of refining agent selected from the group consisting of Cl 2 , F 2 , Sb 2 O 3 and As 2 O 3 , and SO 3 , and from 0 to 3% of R'O where R' is alkaline earth metal atom selected from Ba, Sr and Pb, and said low expansion transparent glass substrate has an expansion coefficient of from 30 to 45×10 -7 /°C. (from 50° to 350° C.), said glass having a temperature at the softening point of from about 890° C. to not higher than 930° C.
Claim 2
Dependent Claim
190 words
A low expansion transparent glass substrate consisting of, all by weight, from 55 to 65% of SiO 2 , from 10 to 20% of Al 2 O 3 , from 2 to 10% of B 2 O 3 , from 3 to 10% of MgO, from 1 to 8% CaO, from 2 to 10% of ZnO, from 1 to 4% of R 2 O where R is an alkali metal atom and of which at least 1% is Na 2 O, from 0.1 to 4% of ZrO 2 , from 0 to 5% of at least one component of refining agent selected from the group consisting of Cl 2 , F 2 , Sb 2 O 3 and As 2 O 3 , and SO 3 , and from 0 to 3% of R'O where R' is alkaline earth metal atom selected from Ba, Sr and Pb, and said low expansion transparent glass substrate has an expansion coefficient of from 30 to 45×10 -7 /°C. (from 50° to 350° C.), said glass having a temperature at the softening point of from about 890° C. to not higher than 930° C.
Claim 3
Dependent Claim
88 words
The low expansion transparent glass substrate according to claim 1, which consists of, all by weight, from 58 to 63% of SiO 2 , from 12 to 15% of Al 2 O 3 , from 3 to 5% of B 2 O 3 , from 5 to 8% of MgO, from 2 to 5% of CaO, from 5 to 9% of ZnO, from 1 to 3% of R 2 O of which at least 1% is Na 2 O, and from 0.1 to 2% of ZrO 2 .
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1990-02-02 | 1990-08-04 | 1991-02-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-02 | 1994-08-04 | 1995-02-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-02 | 1998-08-04 | 1999-02-03 | $7700.00 | Window Closed / Lapsed |