US4581213A
Expired / Lapsed
US
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Crystalline silicic acid, its salts, and processes for their preparation
Assignee: Clariant Produkte Deutschland GmbH
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Filing: 1985-01-02
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Granted: 1986-04-08
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Expires: 2005-01-02
Abstract
Abstract Crystalline sodium silicates having a sheet structure and an ion exchange capacity of 83-130 mmol of Na + /mol of SiO 2 are prepared by a method in which an aqueous reaction mixture which contains sodium silicate, has a molar ratio SiO 2 /Na 2 O of 3.9:1 to 15:1 and a molar ratio H 2 O/(Na 2 O+SiO 2 ) of 3:1 to 80:1 and contains 0.01 to 30% by weight, relative to the amount of SiO 2 in the reaction mixture employed, of seed crystals of the desired crystalline sodium silicate is prepared, the mixture is heated to temperatures of 160° to 250° C., the reaction is carried out at least until, in the X-ray diffraction pattern of a sample filtered off under suction and dried at 120° C., the ratio of the intensity of the reflection at the interplanar spacing d 1 =(20±2)·10 -8 cm to the intensity of any reflection present at the interplanar spacing d 2 =(15.5±1.5)·10 -8 cm is at least 3:1, and the reaction is terminated before the intensity of the reflection at the interplanar spacing d 3 =(3.34±0.04)·10 -8 cm reaches or exceeds the intensity of the reflection at the interplanar spacing d 4 =(3.44±0.04)·10 -8 cm. A crystalline silicic acid having a sheet structure and the overall composition H 2 Si x O 2x+1 , wherein 15<x<24, and its sodium salt are described.
Inventors
- 👤 Hans-Peter Rieck
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 23:49
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/113; C01B33/12; C01B33/20; C01B33/36; C01B33/38
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
89 words
A synthetic crystalline silicic acid which has a sheet structure and an overall composition H 2 Si x O 2x+1 , wherein x denotes a number between 15 and 24, which exhibits a very strong first line in the X-ray diffraction pattern at (3.42±0.1)·10 -8 cm and a further line at (18±4)·10 -8 cm, the intensity of which is not more than 75% of the intensity of the first line, and which has a titratable acidity of 83 to 130 mmol of H + /mol of SiO 2 .
Claim 2
Dependent Claim
89 words
A synthetic crystalline silicic acid which has a sheet structure and an overall composition H 2 Si x O 2x+1 , wherein x denotes a number between 15 and 24, which exhibits a very strong first line in the X-ray diffraction pattern at (3.42±0.1)·10 -8 cm and a further line at (18±4)·10 -8 cm, the intensity of which is not more than 75% of the intensity of the first line, and which has a titratable acidity of 83 to 130 mmol of H + /mol of SiO 2 .
Claim 3
Dependent Claim
80 words
A synthetic crystalline sodium salt of the silicic acid as claimed in claim 1, which exhibits, in the X-ray diffraction pattern, at least one very strong line at (3.42±0.15)·10 -8 cm and a further line at (20±2)·10 -8 cm, the intensity of which is not more than 75% of the intensity of the first line, and has an exchange capacity, which can be determined by titration with sulfuric acid, of 83 to 130 mmol of sodium/mol of SiO 2 .
Claim 4
Dependent Claim
24 words
A sodium salt as claimed in claim 2, wherein the ion exchange capacity is 83 to 105 mmol of sodium/mmol of SiO 2 .
Claim 5
Dependent Claim
209 words
A process for the preparation of a crystalline sodium silicate having a sheet structure and an ion exchange capacity of 83-130 mmol of Na + /mol of SiO 2 , wherein an aqueous reaction mixture which contains sodium silicate, has a molar ratio of SiO 2 /Na 2 O of 3.9:1 to 15:1 and a molar ratio H 2 O/(Na 2 O+SiO 2 ) of 3:1 to 80:1 and contains 0.01 to 30% by weight, relative to the amount of SiO 2 in the reaction mixture employed, of seed crystals of the desired crystalline sodium silicate is prepared, this reaction mixture is heated to temperatures of 160° to 250° C., the reaction is carried out at least until, in the X-ray diffraction pattern of a sample filtered off under suction and dried at 120° C., the ratio of the intensity of the reflection at the inter-planar spacing d 1 =(20±2)·10 -8 cm to the intensity of any reflection present at the interplanar spacing d 2 =(15.5±1.5)·10 -8 cm is at least 3:1, and the reaction is terminated before the intensity of the reflection at the interplanar spacing d 3 =(3.34±0.04)·10 -8 cm reaches or exceeds the intensity of the reflection at the interplanar spacing d 4 =(3.44±0.04)·10 -8 cm.
Claim 6
Dependent Claim
209 words
A process for the preparation of a crystalline sodium silicate having a sheet structure and an ion exchange capacity of 83-130 mmol of Na + /mol of SiO 2 , wherein an aqueous reaction mixture which contains sodium silicate, has a molar ratio of SiO 2 /Na 2 O of 3.9:1 to 15:1 and a molar ratio H 2 O/(Na 2 O+SiO 2 ) of 3:1 to 80:1 and contains 0.01 to 30% by weight, relative to the amount of SiO 2 in the reaction mixture employed, of seed crystals of the desired crystalline sodium silicate is prepared, this reaction mixture is heated to temperatures of 160° to 250° C., the reaction is carried out at least until, in the X-ray diffraction pattern of a sample filtered off under suction and dried at 120° C., the ratio of the intensity of the reflection at the inter-planar spacing d 1 =(20±2)·10 -8 cm to the intensity of any reflection present at the interplanar spacing d 2 =(15.5±1.5)·10 -8 cm is at least 3:1, and the reaction is terminated before the intensity of the reflection at the interplanar spacing d 3 =(3.34±0.04)·10 -8 cm reaches or exceeds the intensity of the reflection at the interplanar spacing d 4 =(3.44±0.04)·10 -8 cm.
Claim 7
Dependent Claim
25 words
The process as claimed in claim 4, wherein the reaction mixture employed has a molar ratio SiO 2 /Na 2 O of 5:1 to 10:1.
Claim 8
Dependent Claim
40 words
A process for the preparation of the crystalline silicic acid as claimed in claim 1, wherein an alkali metal salt of the crystalline silicic acid is treated with a dilute mineral acid, and the silicic acid obtained is filtered off.
Claim 9
Dependent Claim
15 words
A crystalline sodium silicate having a sheet structure made by the process of claim 4.
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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) | 1989-04-07 | 1989-10-07 | 1990-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-04-07 | 1993-10-07 | 1994-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-04-07 | 1997-10-07 | 1998-04-08 | $7700.00 | Window Closed / Lapsed |