EP0227346A2
Expired / Lapsed
EP
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Spheroidal silica
Assignee: Unilever PLC
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Filing: 1986-12-03
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Granted: —
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Expires: 2006-12-03
Abstract
Abstract This invention relates to novel silica spheroids and to their production by a phase separation technique in which an aqueous alkaline stabilised silica sol and an aqueous solution of a non-adsorbing polymer are mixed and acidified to produce the new silica spheroids.
Inventors
- 👤 Michael Joseph Garvey
- 👤 Ian Charles Griffiths
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-02 21:39
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/113; C01B33/12; C01B33/16
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
61 words
A porous spheroidal silica having a particle size in the range l-400 microns, axial ratios of l:l to l:l2, a pore volume in the range 26 to 50% and a narrow pore size distribution in which more than 80% of the porosity is between 50 and 200% of the median pore diameter in the pore size range 20 to l000 Å.
Claim 2
Dependent Claim
61 words
A porous spheroidal silica having a particle size in the range l-400 microns, axial ratios of l:l to l:l2, a pore volume in the range 26 to 50% and a narrow pore size distribution in which more than 80% of the porosity is between 50 and 200% of the median pore diameter in the pore size range 20 to l000 Å.
Claim 3
Dependent Claim
29 words
A porous spheroidal silica as claimed in claim l in which the particle size range is between l and 200 microns and the axial ratios from l:l to l:4.
Claim 4
Dependent Claim
62 words
A process for the preparation of silica spheroids as claimed in claim l 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 5
Dependent Claim
23 words
A process as claimed in claim 3 in which the sol and polymer solutions are mixed at a pH in the range 8.5-10.5.
Claim 6
Dependent Claim
26 words
A process as claimed in claim 3 or claim 4 in which the pH reductions required in the process are carried out in a stepwide manner.
Claim 7
Dependent Claim
31 words
A process as claimed in claim 3, 4 or 5 in which the non-absorbing polymer is selected from sodium dextran sulphate, sodium polyacrylate, sodium carboxymethyl cellulose and mixtures of such polyelectrolytes.
Claim 8
Dependent Claim
33 words
A process as claimed in any one of the claims 3, 4, 5 and 6 in which the polymer concentration to induce phase separation is 0.0l to 20% by weight in the mixture.
Claim 9
Dependent Claim
30 words
A process as claimed in any one of the claims 3 to 7 in which the acidification of the system is carried out to the pH range 4 to 8.5.
References Cited (Backward Citations)
No citation records indexed.
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