US3765859A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of liquid quenching glass sheets
Assignee: PPG Industries Inc
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Filing: 1972-05-15
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Granted: 1973-10-16
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Expires: 1992-05-15
Abstract
Abstract An improved method of quenching heated flat glass is described which involves applying to a surface on or adjacent at least one peripheral edge of the glass prior to heating it, an edge protecting composition taken from the class of compositions having a low coefficient of expansion compared to glass and/or a heat transfer coefficient not greater than glass while maintaining the major surfaces inwardly of each of said surfaces on or adjacent said peripheral edge substantially free of said protective composition. The glass with its edge so treated is then heated to above its strain point and below its softening point (at which temperature range said composition fuses to the glass) and subsequently quenched using a liquid medium having a high heat transfer coefficient.
Inventors
- 👤 S Seymour
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 13:23
CPC Classifications
C; C03; C03B; C03B27/00; C03B27/02; C03B27/022; C03C; C03C4/00
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
76 words
A method of quenching heated flat glass to provide tempered flat glass according to the method of claim 1, comprising applying to at least the peripheral surface of at least one edge of the glass prior to heating a frit having a low melting point and a coefficient of thermal expansion of approximately 7.6 X 10 6 per degree centigrade or less, heating the glass And subsequently quenching the heated glass in a liquid quenching medium.
Claim 2
Dependent Claim
86 words
A method of tempering flat glass according to the method of claim 1, comprising applying to at least the peripheral surface of at least one edge of the flat glass a low melting frit having a coefficient of thermal expansion of approximately 6.8 X 10 6 per degree Centigrade or lower, heating the glass to near its softening point and quenching the glass so heated by contacting it with a liquid heat transfer fluid to rapidly chill the glass to a temperature below its strain point.
Claim 3
Dependent Claim
24 words
The method of claim 1 wherein the quenching liquid is taken from the group consisting of oxyalkylene polymers, silicones, hydrocarbon oils and mixtures thereof.
Claim 4
Dependent Claim
32 words
The method of claim 1, wherein the glass is heated to temperatures above its strain point and near its softening point and is chilled during quenching to temperatures below the strain point.
Claim 5
Dependent Claim
28 words
The method of claim 2 wherein the frit has on a weight percent basis the composition: SiO2 33.8 Al2O3 3.61 Li2O 3.34 PbO 46.50 B2O3 4.45 Na2O 8.30
Claim 6
Dependent Claim
24 words
The method of claim 2 wherein the frit has on a weight percent basis the composition: SiO2 18.52 Al2O3 40.08 Cr2O3 4.52 PbO 35.04
Claim 7
Dependent Claim
26 words
The method of claim 2 wherein the frit has on a weight percent basis the composition: SiO2 36.87 Al2O3 3.94 Li2O 3.64 PbO 50.71 B2O3 4.85
Claim 8
Dependent Claim
20 words
The method of claim 3 wherein the frit has a coefficient of thermal expansion of approximately 6.8 X 10 6.
Claim 9
Dependent Claim
28 words
The method of claim 3, wherein the liquid heat transfer fluid is taken from the group consisting of silicones, oxyalkylene oxides, oxyalkylene glycols, hydrocarbon oils and mixtures thereof.
Claim 10
Dependent Claim
20 words
The method of claim 1, wherein the liquid quenching medium is at temperature of between about 200*F. to about 450*F.
Claim 11
Dependent Claim
32 words
The method of claim 1, wherein the composition applied to the glass edge surface is taken from the group of compositions having a heat transfer coefficient not greater than that of glass.
Claim 12
Dependent Claim
48 words
The method of claim 1, wherein said composition is taken from the group of compositions consisting of dispersions or pastes of one or more pulverulent materials taken from the class consisting of lime, magnesia, magnesium carbonate, mica, calcium sulfate, silica, chalk, diatomaceous earth, lamp black and cerium oxide.
Claim 13
Dependent Claim
31 words
The method of claim 1, wherein the composition applied to the glass edge surface is taken from the group of compositions having a low coefficient of thermal expansion compared to glass.
Claim 14
Dependent Claim
23 words
The method of claim 4, wherein said composition is a glassy frit having a melting point less than that of said flat glass.
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) | 1976-10-15 | 1977-04-16 | 1977-10-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-10-15 | 1981-04-16 | 1981-10-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-10-15 | 1985-04-16 | 1985-10-16 | $7700.00 | Window Closed / Lapsed |