US4738839A
Expired / Lapsed
US
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Process for the preparation of precipitated silica
Assignee: Honeywell Riedel de Haen AG
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Filing: 1986-11-19
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Granted: 1988-04-19
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Expires: 2006-11-19
Abstract
Abstract Crystalline precipitated silica is produced by hydrolyzing silicon tetrachloride in the presence of fluoride ions at a temperature of up to 60° C.
Inventors
- 👤 Bernd Schonfeld
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 08:42
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/113; C01B33/12; C01B33/18; C03; C03C; C03C1/00; C01P; C01P2006/00; C01P2006/80
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
45 words
The process for the preparation of crystalline precipitated silica which comprises hydrolyzing silicon tetrachloride at at temperature of up to 60° C. in the presence of a fluoride ion donator, separating the crystalline hydrolysis product from the reaction mixture and then drying the crystalline silica.
Claim 2
Dependent Claim
45 words
The process for the preparation of crystalline precipitated silica which comprises hydrolyzing silicon tetrachloride at at temperature of up to 60° C. in the presence of a fluoride ion donator, separating the crystalline hydrolysis product from the reaction mixture and then drying the crystalline silica.
Claim 3
Dependent Claim
24 words
The process according to claim 1 wherein the silicon tetrachloride starting material has a degree of purity of at least 99.9 percent by weight.
Claim 4
Dependent Claim
14 words
The process according to claim 1 wherein hydrogen fluoride is the fluoride ion donator.
Claim 5
Dependent Claim
30 words
The process according to claim 1 wherein hydrolysis is in an aqueous medium in which fluoride ions are present in an amount of 0.3 to 3 per cent by weight.
Claim 6
Dependent Claim
19 words
The process according to claim 1 wherein hydrolysis is carried out at a temperature of 20° to 50° C.
Claim 7
Dependent Claim
35 words
The process according to claim 1 wherein drying is in two stages, the first stage at a temperature of 100° to 130° C. and the second stage at a temperature of 600° to 900° C.
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) | 1991-04-19 | 1991-10-19 | 1992-04-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-04-19 | 1995-10-19 | 1996-04-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-04-19 | 1999-10-19 | 2000-04-19 | $7700.00 | Window Closed / Lapsed |