US4956167A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Silicas
Assignee: Ineos Silicas Ltd
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Filing: 1989-03-22
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Granted: 1990-09-11
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Expires: 2009-03-22
Abstract
Abstract An amorphous silica, especially precipitated silica, suitable for use in toothpastes, has a high abrasivity represented by a perspex abrasion value in the range from about 23 to about 35.
Inventors
- 👤 Derek Aldcroft
- 👤 John R. Newton
- 👤 James P. Quinn
- 👤 Peter W. Stanier
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 16:42
CPC Classifications
A; A61; A61Q; A61Q11/00; A61K; A61K8/00; A61K8/18; A61K8/19; A61K8/25; C; C01; C01B; C01B33/00; C01B33/113; C01B33/12; C01B33/18; C01B33/187; C01B33/193; C01P; C01P2002/00; C01P2002/02; C01P2004/00; C01P2004/60; C01P2004/61; C01P2006/00; C01P2006/10; C01P2006/12; C01P2006/19; C01P2006/80; C01P2006/82; C01P2006/90
Claims Analysis
Total Claims: 3
Claim 1
Independent Claim
208 words
A method of preparing an amorphous precipitated silica, suitable for use as a toothpaste abrasive, and having (i) a BET surface area in the range from about 10 to about 450 pl m 2 /g, (ii) a weight mean particle size in the range from about 3 to about 20 microns, and (iii) a perspex abrasion value in the range from about 23 to about 35, which is produced by the reaction of sodium silicate, having a silica:Na 2 O ratio in the range from 1.8 to 3.5:1, with mineral acid at a temperature of about 95° C. to 100° C., with the concentration and volume of the reactants controlled to give a reaction in the pH range from about 10 to about 10.5, in the presence of a water soluble electrolyte comprising a cation selected from the group comprising aluminium, magnesium, calcium, sodium and potassium with an associated anion selected from the group comprising bromide, carbonate, chloride, nitrate, acetate and sulphate wherein the electrolyte:silica weight ratio is from about 0.1 to 1 to about 2 to 1, adding mineral acid to lower the pH to the range of 3.0-3.5, while at least maintaining the reaction temperature and thereafter filtering the resultant slurry and recovering the precipitated silica.
Claim 2
Independent Claim
208 words
A method of preparing an amorphous precipitated silica, suitable for use as a toothpaste abrasive, and having (i) a BET surface area in the range from about 10 to about 450 pl m 2 /g, (ii) a weight mean particle size in the range from about 3 to about 20 microns, and (iii) a perspex abrasion value in the range from about 23 to about 35, which is produced by the reaction of sodium silicate, having a silica:Na 2 O ratio in the range from 1.8 to 3.5:1, with mineral acid at a temperature of about 95° C. to 100° C., with the concentration and volume of the reactants controlled to give a reaction in the pH range from about 10 to about 10.5, in the presence of a water soluble electrolyte comprising a cation selected from the group comprising aluminium, magnesium, calcium, sodium and potassium with an associated anion selected from the group comprising bromide, carbonate, chloride, nitrate, acetate and sulphate wherein the electrolyte:silica weight ratio is from about 0.1 to 1 to about 2 to 1, adding mineral acid to lower the pH to the range of 3.0-3.5, while at least maintaining the reaction temperature and thereafter filtering the resultant slurry and recovering the precipitated silica.
Claim 3
Dependent Claim
30 words
A method according to claim 1 wherein the reaction medium is subjected to a hydrothermal ageing step during the acid addition which lowers the pH to the range of 3.0-3.5.
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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) | 1993-09-10 | 1994-03-12 | 1994-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-09-10 | 1998-03-12 | 1998-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-09-10 | 2002-03-12 | 2002-09-11 | $7700.00 | Window Closed / Lapsed |