US 12,077,444 B2
Precipitated silica with improved processing properties
Frédéric Colbeau-Justin, Collonges au Mont d'Or (FR); Cédric Boivin, Chasselay (FR); Cyril Chomette, Mérignac (FR); Thomas Chaussee, Cailloux-sur-Fontaines (FR); and Laurent Guy, Sathonay-Camp (FR)
Assigned to RHODIA OPERATIONS, Aubervilliers (FR)
Appl. No. 17/253,197
Filed by RHODIA OPERATIONS, Aubervilliers (FR)
PCT Filed Jul. 12, 2019, PCT No. PCT/EP2019/068836
§ 371(c)(1), (2) Date Dec. 17, 2020,
PCT Pub. No. WO2020/011984, PCT Pub. Date Jan. 16, 2020.
Claims priority of application No. 18305945 (EP), filed on Jul. 13, 2018; and application No. 18209037 (EP), filed on Nov. 29, 2018.
Prior Publication US 2021/0114889 A1, Apr. 22, 2021
Int. Cl. C08K 3/36 (2006.01); C01B 33/193 (2006.01); C08L 9/06 (2006.01); C08L 23/22 (2006.01); B60C 1/00 (2006.01)
CPC C01B 33/193 (2013.01) [C08L 9/06 (2013.01); C08L 23/22 (2013.01); B60C 1/0016 (2013.01); B60C 2200/04 (2013.01); C01P 2004/51 (2013.01); C01P 2006/12 (2013.01); C08K 3/36 (2013.01)] 19 Claims
 
1. A process for preparing a precipitated silica, comprising the steps of:
(i) providing a starting solution having a pH from 2.0 to 5.0,
(ii) simultaneously adding a silicate and an acid to said starting solution such that the pH of the reaction medium is maintained in the range from 2.0 to 5.0,
(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 7.0 to 10.0,
(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 7.0 to 10.0,
(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 5.5 and obtaining a first suspension of precipitated silica,
(vi) submitting said first suspension of precipitated silica to filtration to provide a filter cake;
(vii) submitting said filter cake to a liquefaction step in the presence of a mineral acid such that the pH of the resulting precipitated silica is less than 5.5, to obtain a second suspension of precipitated silica; and
(viii) optionally, drying the precipitated silica obtained after the liquefaction step, wherein the so prepared precipitated silica has
a CTAB surface area SCTAB greater than 140 m2/g;
a width of the aggregate size distribution Ld, measured by centrifugal sedimentation, of at least 1.2;
a pH of less than 5.5; and
a carbon content of less than 1500 ppm.