Patent US5647962A successfully refreshed from Google Patents.
US5647962A
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Process for the preparation of xerogels
Assignee: Cabot Corp
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Filing: 1995-06-28
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Granted: 1997-07-15
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Expires: 2015-06-28
Abstract
Abstract The invention relates to modified SiO 2 gels (xerogels), the preparation thereof and the use thereof as thermal insulators. The xerogels are prepared by acidifying an aqueous waterglass solution, polycondensing the silicic acid produced thereby, by adding a base, to an SiO 2 gel, removing the water from the resulting gel by extractive distillation with an organic solvent which forms with water an azeotrope which separates on cooling into two phases, reacting the gel with a silylating agent, and then drying at pressures and temperatures which are below the critical pressure and/or the critical temperature of the organic solvent used for removing the water.
Inventors
- 👤 Rolf-Michael Jansen
- 👤 Andreas Zimmermann
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 01:47
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/113; C01B33/12; C01B33/14; C01B33/152; C01B33/154; C01B33/1543; C04; C04B; C04B30/00
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
129 words
A process for the preparation of xerogels, which comprises a) adjusting an aqueous waterglass solution to a pH≦3.0, using an acid ion exchange resin or a mineral acid, b) polycondensing the silicic acid produced thereby, by adding a base, to an SiO 2 gel c) removing the water from the gel obtained in step b) by extractive distillation with an organic solvent which forms with water an azeotrope which separates into two phases on cooling, until the water content of the gel is ≦5% by weight, d) reacting the gel obtained in step c) with a silylating agent, e) drying the silylated gel obtained in step d) at pressures and temperatures which are below the critical pressure and/or the critical temperature of the organic solvent used in step c).
Claim 2
Dependent Claim
129 words
A process for the preparation of xerogels, which comprises a) adjusting an aqueous waterglass solution to a pH≦3.0, using an acid ion exchange resin or a mineral acid, b) polycondensing the silicic acid produced thereby, by adding a base, to an SiO 2 gel c) removing the water from the gel obtained in step b) by extractive distillation with an organic solvent which forms with water an azeotrope which separates into two phases on cooling, until the water content of the gel is ≦5% by weight, d) reacting the gel obtained in step c) with a silylating agent, e) drying the silylated gel obtained in step d) at pressures and temperatures which are below the critical pressure and/or the critical temperature of the organic solvent used in step c).
Claim 3
Dependent Claim
18 words
The process as claimed in claim 1, wherein an acid ion exchange resin is employed in step a).
Claim 4
Dependent Claim
31 words
The process as claimed in claim 1, wherein the base in step b) is selected from the group consisting of NH 4 OH, NaOH, KOH, Al(OH) 3 and colloidal silicic acid.
Claim 5
Dependent Claim
51 words
The process as claimed in claim 1, wherein the SiO 2 gel obtained in step b) is allowed to age at 0° to 150° C. and at a pH of 4 to 11 for a period of from 10 seconds to 48 hours before the water is removed in step c).
Claim 6
Dependent Claim
28 words
The process as claimed in claim 1, wherein the organic solvent in step c) is selected from the group consisting of toluene, di-n-butyl ether and methyl isobutyl ketone.
Claim 7
Dependent Claim
28 words
The process as claimed in claim 1, wherein the silylating agent in step d) is selected from the group consisting of mono-, di- or trimethylchlorosilane, trimethylmethoxysilane and hexamethyldisilazane.
Claim 8
Dependent Claim
21 words
The process as claimed in claim 1, wherein the silylated gel is dried at -30° to 200° C. in step e).
Claim 9
Dependent Claim
21 words
The process as claimed in claim 1, wherein the silylated gel is dried under 0.001 to 20 bar in step e).
Claim 10
Dependent Claim
124 words
A process for the preparation of xerogels, which comprises a) adjusting an aqueous waterglass solution to a pH ≦3.0, using a mineral acid, b) polycondensing the silicic acid produced thereby, by adding a base, to an SiO 2 gel, c) removing the water from the gel obtained in step b) by extractive distillation with an organic solvent which forms with water an azeotrope which separates into two phases on cooling, until the water content of the gel is ≦5% by weight, d) reacting the gel obtained in step c) with a silylating agent, e) drying the silylated gel obtained in step d) at pressures and temperatures which are below the critical pressure and/or the critical temperature of the organic solvent used in step c).
Claim 11
Dependent Claim
124 words
A process for the preparation of xerogels, which comprises a) adjusting an aqueous waterglass solution to a pH ≦3.0, using a mineral acid, b) polycondensing the silicic acid produced thereby, by adding a base, to an SiO 2 gel, c) removing the water from the gel obtained in step b) by extractive distillation with an organic solvent which forms with water an azeotrope which separates into two phases on cooling, until the water content of the gel is ≦5% by weight, d) reacting the gel obtained in step c) with a silylating agent, e) drying the silylated gel obtained in step d) at pressures and temperatures which are below the critical pressure and/or the critical temperature of the organic solvent used in step c).
Claim 12
Dependent Claim
134 words
A process for the preparation of xerogels, which comprises a) adjusting an aqueous waterglass solution to a pH ≦3.0, using a mineral acid, b) polycondensing the silicic acid produced thereby, by adding a base, to an SiO 2 gel and washing the gel with water until free of electrolytes, c) removing the water from the gel obtained in step b) by extractive distillation with an organic solvent which forms with water an azeotrope which separates into two phases on cooling, until the water content of the gel is ≦5% by weight, d) reacting the gel obtained in step c) with a silylating agent, e) drying the silylated gel obtained in step d) at pressures and temperatures which are below the critical pressure and/or the critical temperature of the organic solvent used in step c).
Claim 13
Dependent Claim
134 words
A process for the preparation of xerogels, which comprises a) adjusting an aqueous waterglass solution to a pH ≦3.0, using a mineral acid, b) polycondensing the silicic acid produced thereby, by adding a base, to an SiO 2 gel and washing the gel with water until free of electrolytes, c) removing the water from the gel obtained in step b) by extractive distillation with an organic solvent which forms with water an azeotrope which separates into two phases on cooling, until the water content of the gel is ≦5% by weight, d) reacting the gel obtained in step c) with a silylating agent, e) drying the silylated gel obtained in step d) at pressures and temperatures which are below the critical pressure and/or the critical temperature of the organic solvent used in step c).
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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) | 2000-07-14 | 2001-01-13 | 2001-07-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-07-14 | 2005-01-13 | 2005-07-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-07-14 | 2009-01-13 | 2009-07-15 | $7700.00 | Window Closed / Lapsed |