Patent ID: 11958980
Assignee: RHODIA OPERATIONS
Field: Macromolecular chemistry, polymers (Chemistry)
Classification: CPC C | IPC C

Claim 7:
8. A process for preparing the precipitated silica of claim 1, which comprises:
(i) providing a starting solution comprising at least a portion of a total amount of at least one alkali metal alkyl siliconate, at least a portion of a total amount of a silicate involved in a precipitation reaction and optionally an electrolyte, the concentration of the silicate in the starting solution being less than 100 g/L;
(ii) adding an amount of an acid to said starting solution to obtain a reaction medium having a pH value for the reaction medium of at least 7.0; and
(iii) further adding an acid and, if appropriate, simultaneously the remaining portion of the silicate to the reaction medium to obtain a silica suspension;
wherein the remaining portion of the at least one alkali metal alkyl siliconate, if any, is metered into the reaction medium in at least one of steps (ii) or (iii), with the proviso that the total amount of the alkali metal siliconate is added to the reaction medium before 50% of the precipitation reaction has taken place.