US4778667A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Spheroidal silica
Assignee: Unilever Patent Holdings BV
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Filing: 1986-12-02
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Granted: 1988-10-18
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Expires: 2006-12-02
Abstract
Abstract This invention relates to novel silica spheroids and to their production by a phase separation technique in which an aqueous alkaline stabilized silica sol and an aqueous solution of a non-adsorbing polymer are mixed and acidified to produce the new silica spheroids.
Inventors
- 👤 Michael J. Garvey
- 👤 Ian C. Griffiths
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-05 15:37
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/113; C01B33/12; C01B33/16
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
57 words
A process for the preparation of silica spheroids comprising mixing together under alkaline conditions an aqueous alkali stabilised silica sol and an aqueous solution of a non-adsorbing polymer to form a phase separated system comprising silica droplets in a polymer rich continuous aqueous phase and acidifying the system to aggregate the droplets to form the silica spheroids.
Claim 2
Dependent Claim
57 words
A process for the preparation of silica spheroids comprising mixing together under alkaline conditions an aqueous alkali stabilised silica sol and an aqueous solution of a non-adsorbing polymer to form a phase separated system comprising silica droplets in a polymer rich continuous aqueous phase and acidifying the system to aggregate the droplets to form the silica spheroids.
Claim 3
Dependent Claim
23 words
A process as claimed in claim 1 in which the sol and polymer solutions are mixed at a pH in the range 8.5-10.5.
Claim 4
Dependent Claim
23 words
A process as claimed in claim 1, in which the pH reductions required in the process are carried out in a stepwide manner.
Claim 5
Dependent Claim
28 words
A process as claimed in claim 1, in which the non-absorbing polymer is selected from sodium dextran sulphate, sodium polyacrylate, sodium carboxymethyl cellulose and mixtures of such polyelectrolytes.
Claim 6
Dependent Claim
25 words
A process as claimed in claim 1 in which the polymer concentration to induce phase separation is 0.01 to 20% by weight in the mixture.
Claim 7
Dependent Claim
24 words
A process as claimed in claim 1 in which the acidification of the system is carried out to the pH range 4 to 8.5.
References Cited (Backward Citations)
FR1529058A
Cited
GB1433242A
Cited
GB1452896A
Cited
GB1506114A
Cited
US4255286A
Cited
GB2127002A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1991-10-18 | 1992-04-18 | 1992-10-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1995-10-18 | 1996-04-18 | 1996-10-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1999-10-18 | 2000-04-18 | 2000-10-18 | $7700.00 | Window Closed / Lapsed |