Precipitated Silica and Process for Its Manufacture
AssigneeRhodia Operations
InventorsCédric Feral-Martin, Emmanuelle Allain Najman, Pascaline Lauriol-Garbey, Thomas Chaussee, Laurent Guy
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Abstract
The present invention relates to precipitated silica having small sized particles and to a process for its manufacture. The invention further relates to the use of precipitated silica as reinforcing filler in polymeric compositions, preferably elastomeric compositions.
Claims27
A precipitated silica having:
- a CTAB surface area in the range from 40 to 300 m2/g;
- primary particles having an average size dzs measured by SAXS below 11 nm;
- a median particle size d50 measured by centrifugal sedimentation such that:
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- d
- 50
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- <
- -
- 0.782
- ×
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- CTAB
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- +
- 255.
- (
- I
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The precipitated silica according to claim 21, having a CTAB surface area greater than 150 m2/g and lower than 210 m2/g.
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A process for preparing a precipitated silica, said process comprising:
- (i) providing a starting solution having a pH from 2.00 to 5.50,
- (ii) simultaneously adding a silicate and an acid to said starting solution to obtain a reaction medium of which the pH is maintained in the range from 2.00 to 5.50,
- (iii) stopping the addition of the acid and of the silicate and adding a base to the reaction medium to raise the pH of said reaction medium to a value from 7.00 to 10.00,
- (iv) simultaneously adding to the reaction medium a silicate and an acid, such that the pH of the reaction medium is maintained in the range from 7.00 to 10.00,
- (v) stopping the addition of the silicate while continuing the addition of the acid to the reaction medium to reach a pH of the reaction medium of less than 6.00 and obtaining a suspension of precipitated silica,
- wherein a point of gel is reached during step (ii) and wherein the amount of silicate added during step (ii) after the point of gel is reached is between 5% and 55% of the total amount of silicate added at the end of step (ii).
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23-25. (canceled)
28-34. (canceled)
Dependencies are inferred from the claim text.