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US 2025/0162887 A1Published application
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 an improved dispersability 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.
Claims33
A precipitated silica comprising:
- a CTAB surface area in a range from 40 to 525 m2/g;
- primary particles having an average size measured by SAXS below 15 nm;
- a rate of fines τf, that is to say a proportion (by weight) of particles of a size less than 1 m after deagglomeration by ultrasounds, which is of at least 91%;
- and
- a particle size distribution measured by centrifugal sedimentation using a CPS, such that for a given value of the CTAB surface area, a parameter FWHM is defined by relation (I):
- ❘
- "\[LeftBracketingBar]"
- FWHM
- ❘
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- >
- -
- 0.16
- ×
- ❘
- "\[LeftBracketingBar]"
- CTAB
- ❘
- "\[RightBracketingBar]"
- +
- 130
- (
- I
- )
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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 step (i) comprises the following steps:
- (ia) providing an aqueous medium eventually comprising an electrolyte as initial stock, (ib) simultaneously adding to this aqueous medium a silicate and an acid, such that the pH of the aqueous medium is maintained in the range from 7.00 to 10.00, wherein the amount of silicate added to the aqueous medium is between 1 and 10% of the total amount of silicate required for the reaction,
- (ic) stopping the addition of silicate while continuing the addition of the acid to the aqueous medium obtained in step (ib) in order to provide the starting solution having a pH from 2.00 to 5.50.
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Dependencies are inferred from the claim text.