US4915870A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for the manufacture of potassium stabilized silica sols
Assignee: Ecolab USA Inc
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Filing: 1988-10-07
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Granted: 1990-04-10
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Expires: 2008-10-07
Abstract
Abstract A method for producing a silica sols containing less than 150 ppm sodium haivng an average particle size of 2-110 nm, and a particle size distribution with a coefficient dispersion of 0.16-0.4. The silica sols are produced using a KOH heal to which aliquots of modified silicic acid containing acidic anions are added. The aliquots are added to maintain a substantially constant concentration of colloidal silica in the product. Subsequent to production, the sols may be concentrated by ultrafiltration. Preparation of low sodium silica sols utilizing a constant silica technique by heating the initial heel to a temperature greater than 80° C. and adding additional silica maintaining an approximately constant total silica. The stabilization is effected with a KOH.
Inventors
- 👤 Robert D. Jones
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 13:13
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/113; C01B33/12; C01B33/14; C01B33/146; C01B33/148
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
174 words
A method for producing a low sodium silica sol comprising the following steps: A. providing a 0.1%-5% aqueous solution of potassium hydroxide, B. heating the aqueous solution of the potassium hydroxide to at least 80° C., C. preparing a modified acid sol by mixing aqueous silicic acid and another acid in a weight ratio of silicic acid to the other acid within the range of from 10:1 to 150:1; D. Adding to the heated aqueous solution of the KOH a 2 to 10% by weight modified acid sol in a volume ratio of from 2:1 to 15:1, the mole ratio of Sio 2 : KOH being in the range of 1:1 to 150:1, at a rate which maintains a substantially constant, concentration of SiO 2 in the resultant mixture thereby producing the silica sol and then, E. concentrating the silica sol by either distillation or ultrafiltration so as to recover an aqueous colloidal silica sols which contains 5-55% by weight SiO 2 having a pH of 8-10.5 and containing less than 150ppm sodium metal.
Claim 2
Independent Claim
174 words
A method for producing a low sodium silica sol comprising the following steps: A. providing a 0.1%-5% aqueous solution of potassium hydroxide, B. heating the aqueous solution of the potassium hydroxide to at least 80° C., C. preparing a modified acid sol by mixing aqueous silicic acid and another acid in a weight ratio of silicic acid to the other acid within the range of from 10:1 to 150:1; D. Adding to the heated aqueous solution of the KOH a 2 to 10% by weight modified acid sol in a volume ratio of from 2:1 to 15:1, the mole ratio of Sio 2 : KOH being in the range of 1:1 to 150:1, at a rate which maintains a substantially constant, concentration of SiO 2 in the resultant mixture thereby producing the silica sol and then, E. concentrating the silica sol by either distillation or ultrafiltration so as to recover an aqueous colloidal silica sols which contains 5-55% by weight SiO 2 having a pH of 8-10.5 and containing less than 150ppm sodium metal.
Claim 3
Dependent Claim
23 words
The method of claim 1, where in Step B the aqueous solution is selected to a temperature within the range of 80°-130° C.
Claim 4
Dependent Claim
33 words
The method of claim 2 wherein the other acid specific in step C is a water-soluble acid having an anion selected from the group consisting of chloride, nitrate, sulfate, sulfite, phosphate, and acetate.
Claim 5
Dependent Claim
23 words
The method of claim 3, wherein in Step B the aqueous solution is heated to a temperature within the range of 90°-130° C.
Claim 6
Dependent Claim
37 words
The method of claim 3 wherein a constant concentration of 2 to 6 weight % SiO 2 is maintained in the mixture formed when modified acid sol is added to the aqueous heated solution of potassium hydroxide.
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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) | 1993-04-09 | 1993-10-09 | 1994-04-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-04-09 | 1997-10-09 | 1998-04-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-04-09 | 2001-10-09 | 2002-04-10 | $7700.00 | Window Closed / Lapsed |