US4590052A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Precipitated silica having improved morphological characteristics and process for the production thereof
Assignee: Rhone Poulenc Chimie de Base SA
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Filing: 1985-04-05
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Granted: 1986-05-20
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Expires: 2005-04-05
Abstract
Abstract A precipitated silica having improved morphological characteristics and a process for making precipitated silica. In the precipitated silica of the present invention, the ratio of DBP oil index/CTAB specific surface area is between: 7 and 4 for a range of CTAB of between 50-100 m2/g, 4 and 2.5 for a range of CTAB of between 100-200 m2/g, 2.5 and 2 for a range of CTAB of between 200-250 m2/g, 2 and 1.5 for a range of CTAB of between 250-300 m2/g, and 1.5 and 1.2 for a range of CTAB of between 300-350 m2/g.
Inventors
- 👤 Yvonick Chevallier
- 👤 Jean-Claude Morawski
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 15:07
CPC Classifications
C; C01; C01B; C01B33/00; C01B33/113; C01B33/12; C08; C08K; C08K3/00; C08K3/34; C08K3/36; C01B33/18; C01B33/187; C01B33/193; C01P; C01P2006/00; C01P2006/12; C01P2006/19; C01P2006/90
Claims Analysis
Total Claims: 20
Claim 1
Independent Claim
104 words
A precipitated silica having a BET surface area of between about 50 and 350 m 2 /g, a CTAB specific area between 50 and 350 m 2 /g and a value of oil absorption (DBP) such that the ratio of DBP/CTAB is between: 7 and 4 for a CTAB range between 50-100 m 2 /g; 4 and 2.5 for a CTAB range between 100-200 m 2 /g; 2.5 and 2 for a CTAB range between 200-250 m 2 /g; 2 and 1.5 for a CTAB range between 250-300 m 2 /g; and 1.5 and 1.2 for a CTAB range between 300-350 m 2 /g.
Claim 2
Dependent Claim
104 words
A precipitated silica having a BET surface area of between about 50 and 350 m 2 /g, a CTAB specific area between 50 and 350 m 2 /g and a value of oil absorption (DBP) such that the ratio of DBP/CTAB is between: 7 and 4 for a CTAB range between 50-100 m 2 /g; 4 and 2.5 for a CTAB range between 100-200 m 2 /g; 2.5 and 2 for a CTAB range between 200-250 m 2 /g; 2 and 1.5 for a CTAB range between 250-300 m 2 /g; and 1.5 and 1.2 for a CTAB range between 300-350 m 2 /g.
Claim 3
Dependent Claim
24 words
A precipitated silica according to claim 1 characterized in that it has a BET surface area/CTAB surface area ratio of between 1 and 1.2.
Claim 4
Dependent Claim
16 words
A precipitated silica according to claim 2 having a pH value of about 3.5 to 7.5.
Claim 5
Dependent Claim
16 words
A precipitated silica according to claim 1 having a pH value of about 3.5 to 7.5.
Claim 6
Dependent Claim
129 words
A process for producing a precipitated silica as recited in claim 1 which comprises: (a) forming a vessel bottoms containing from about 60 to 100% by weight of silicate; (b) adding acid until a gel appears, with time and temperature conditions during said addition being regulated to provide gelation between about 10 and 15 minutes; (c) stopping addition of said acid for about 5 to 30 minutes and aging said gel; (d) adding acid after said aging ends until the pH-value is at most equal to about 9; (e) effecting post-treatment; (f) filtering, washing and drying said gel and recovering the product obtained; and (g) introducing an electrolyte in an amount effective to improve the DBP/CTAB ratio in at least one of steps (a), (b), (c), (d) or (e).
Claim 7
Dependent Claim
20 words
A process according to claim 5 wherein said electrolyte is a salt of an alkali metal or alkaline earth metal.
Claim 8
Dependent Claim
31 words
A process according to claim 6 wherein said electrolyte is an alkali metal salt and is added at a concentration from about 0.05 to 0.7 moles per liter of reaction volume.
Claim 9
Dependent Claim
32 words
A process according to claim 6 wherein said electrolyte is an alkaline earth metal salt and is added at a concentration from about 0.001 to 0.01 moles per liter of reaction volume.
Claim 10
Dependent Claim
13 words
A process according to claim 5 wherein said electrolyte is introduced only once.
Claim 11
Dependent Claim
14 words
A process according to claim 5 wherein said electrolyte is introduced more than once.
Claim 12
Dependent Claim
15 words
A process according to claim 5 wherein said electrolyte is introduced before said gel appears.
Claim 13
Dependent Claim
17 words
A process according to claim 5 wherein said electrolyte is introduced at the appearance of said gel.
Claim 14
Dependent Claim
15 words
A process according to claim 5 wherein said electrolyte is introduced after the gel appears.
Claim 15
Dependent Claim
85 words
A process according to claim 5 characterized in that the drying operation is performed by forming a symmetrical vortex spinning flow configuration with a hot gas having a high level of momentum and introducing the silica suspension along the axis of rotation of said flow configuration into the relative depression region thereof, the momentum of the vortex-flow configuration which is symmetrical with respect to the axial flow of the suspension being sufficient to cause the axial flow to be broken down, dispersed and taken over.
Claim 16
Dependent Claim
12 words
A reinforcing agent for elastomers comprising the precipitated silica of claim 1.
Claim 17
Dependent Claim
10 words
A thickening agent comprising the precipitated silica of claim 1.
Claim 18
Dependent Claim
18 words
A process according to claim 5 wherein said post-treatment provides a pH-value of between about 7 and 9.
Claim 19
Dependent Claim
25 words
A process according to claim 17, wherein said post-treatment comprises simultaneous addition of acid and silicate at a pH-value of between about 7 and 9.
Claim 20
Dependent Claim
16 words
A process according to claim 5 wherein said post-treatment comprises treatment with acid at decreasing pH-value.
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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) | 1989-05-19 | 1989-11-18 | 1990-05-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-19 | 1993-11-18 | 1994-05-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-19 | 1997-11-18 | 1998-05-20 | $7700.00 | Window Closed / Lapsed |