US3753674A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Thermal tempering of glass having short strain point-to-softening point interval
Assignee: PPG Industries Inc
•
Filing: 1971-01-18
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Granted: 1973-08-21
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Expires: 1991-01-18
Abstract
Abstract Thermal tempering propensity of alkali-alkaline earth-silica glass can be enhanced by changing the chemical composition such that the temperature interval between the softening point and the strain point is decreased. Addition of B2O3 and/or TiO2 in commercial alkali-alkaline earth-silica glass yields the abovementioned result.
Inventors
- 👤 S Ohlberg
- 👤 L Orr
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 23:10
CPC Classifications
C; C03; C03C; C03C3/00; C03C3/04; C03C3/076; C03C3/089; C03B; C03B27/00; C03C3/078; Y; Y02; Y02P; Y02P40/00; Y02P40/50; Y02P40/57
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
32 words
The process of claim 1 wherein sufficient quenching fluid is supplied to the flat glass article to develop in the surface a compressive stress of at least 18,000 pounds per square inch.
Claim 2
Dependent Claim
13 words
A thermally tempered flat glass article prepared by the process of claim 1.
Claim 3
Dependent Claim
19 words
The tempered flat glass article of claim 3 wherein the glass is not in excess of one-eighth inch thick.
Claim 4
Dependent Claim
25 words
The tempered flat glass article of claim 3 wherein compressive stress at the surface of the glass is at least 18,000 pounds per square inch.
References Cited (Backward Citations)
US2198739A
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US2285595A
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US2285596A
Cited
US2311846A
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US2418489A
Cited
US3595725A
Cited
US3620706A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-08-20 | 1977-02-19 | 1977-08-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-08-20 | 1981-02-19 | 1981-08-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-08-20 | 1985-02-19 | 1985-08-21 | $7700.00 | Window Closed / Lapsed |