US5417951A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the hydrothermal production of crystalline sodium disilicate
Assignee: Henkel AG and Co KGaA
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Filing: 1991-11-22
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Granted: 1995-05-23
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Expires: 2011-11-22
Abstract
Abstract The invention is a process for the hydrothermal production of crystalline sodium disilicate by heating an aqueous mixture of quartz sand and sodium hydroxide or an aqueous solution of sodium disilicate with a solids content of at least 50% by weight or more than 75% by weight at a temperature above 235° C. and under autogenous pressure to form crystalline sodium disilicate.
Inventors
- 👤 Guenther Just
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 06:24
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/20; C01B33/36; C01B33/38
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
138 words
A process for the hydrothermal production of solid, crystalline sodium disilicate in the β form with a molar ratio of Na 2 O to SiO 2 of 1:2, said process comprising steps of: (a) reacting a mixture of quartz sand and sodium hydroxide, and, optionally, an aqueous solution of amorphous sodium disilicate in a pressure vessel at a temperature of at least 235° C. and under the water vapor pressure corresponding to that temperature, (a) said mixture having a molar ratio of Na 2 O to SiO 2 of 1:2 and a total solids concentration of more than 75% by weight, for a sufficient time to form crystalline sodium disilicate; (b) concentrating the total solids content of the mixture of step (a) by removal of water from the mixture; and (c) cooling the solid crystalline sodium disilicate produced.
Claim 2
Dependent Claim
138 words
A process for the hydrothermal production of solid, crystalline sodium disilicate in the β form with a molar ratio of Na 2 O to SiO 2 of 1:2, said process comprising steps of: (a) reacting a mixture of quartz sand and sodium hydroxide, and, optionally, an aqueous solution of amorphous sodium disilicate in a pressure vessel at a temperature of at least 235° C. and under the water vapor pressure corresponding to that temperature, (a) said mixture having a molar ratio of Na 2 O to SiO 2 of 1:2 and a total solids concentration of more than 75% by weight, for a sufficient time to form crystalline sodium disilicate; (b) concentrating the total solids content of the mixture of step (a) by removal of water from the mixture; and (c) cooling the solid crystalline sodium disilicate produced.
Claim 3
Dependent Claim
18 words
A process as claimed in claim 1, wherein a ball-containing roller autoclave is used as the pressure vessel.
Claim 4
Dependent Claim
20 words
A process as claimed in claim 2, wherein the reaction temperature is in the range from 250° to 280° C.
Claim 5
Dependent Claim
25 words
A process as claimed in claim 3, wherein concentration is carried out by removal of water during the heating of the mixture of step (a).
Claim 6
Dependent Claim
20 words
A process as claimed in claim 2, wherein the reaction temperature is in the range from 235° to 300° C.
Claim 7
Dependent Claim
20 words
A process as claimed in claim 1, wherein the reaction temperature is in the range from 235° to 300° C.
Claim 8
Dependent Claim
20 words
A process as claimed in claim 6, wherein the reaction temperature is in the range from 250° to 280° C.
Claim 9
Dependent Claim
25 words
A process as claimed in claim 7, wherein concentration is carried out by removal of water during the heating of the mixture of step (a).
Claim 10
Dependent Claim
25 words
A process as claimed in claim 6, wherein concentration is carried out by removal of water during the heating of the mixture of step (a).
Claim 11
Dependent Claim
25 words
A process as claimed in claim 5, wherein concentration is carried out by removal of water during the heating of the mixture of step (a).
Claim 12
Dependent Claim
25 words
A process as claimed in claim 2, wherein concentration is carried out by removal of water during the heating of the mixture of step (a).
Claim 13
Dependent Claim
25 words
A process as claimed in claim 1, wherein concentration is carried out by removal of water during the heating of the mixture of step (a).
References Cited (Backward Citations)
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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) | 1998-05-22 | 1998-11-21 | 1999-05-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-05-22 | 2002-11-21 | 2003-05-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-05-22 | 2006-11-21 | 2007-05-23 | $7700.00 | Window Closed / Lapsed |