The invention relates to the use of carboxylic acid during the preparation of precipitated silica or a suspension of precipitated silica and to the precipitated silicas thus obtained, particularly with low water uptake, which can be used, for example, as a reinforcing filler in silicon matrices.

The invention relates to a process for the preparation of a novel precipitated silica, wherein: a silicate is reacted with an acidifying agent, so as to obtain a silica suspension; said silica suspension is filtered, so as to obtain a filter cake; said filter cake is subjected to a liquefaction operation, in the absence of an aluminium compound; wherein a mixture of polycarboxylic acids is added to the filter cake, during or after the liquefaction operation. It also relates to novel precipitated silicas and to their uses.

The invention relates to a process for the preparation of a novel precipitated silica, wherein: a silicate is reacted with an acidifying agent, so as to obtain a silica suspension; said silica suspension is filtered, so as to obtain a filter cake; said filter cake is subjected to a liquefaction operation, in the absence of an aluminium compound; wherein a mixture of polycarboxylic acids is added to the filter cake, during or after the liquefaction operation. It also relates to novel precipitated silicas and to their uses.

The invention relates to a process for preparing a precipitated silica, to precipitated silicas, and to uses thereof. The process of the invention generally includes reacting a silicate with an acidifying agent, so as to obtain a suspension of precipitated silica; filtering the precipitated silica to obtain a filter cake; subjecting the filter cake to a liquefaction operation to form a second filter cake; and drying the second filter cake. In the process of the invention, at least one polycarboxylic acid is added to the filter cake, during or after the liquefaction operation

The invention relates to a process for preparing a precipitated silica, to precipitated silicas, and to uses thereof. The process of the invention generally includes reacting a silicate with an acidifying agent, so as to obtain a suspension of precipitated silica; filtering the precipitated silica to obtain a filter cake; subjecting the filter cake to a liquefaction operation to form a second filter cake; and drying the second filter cake. In the process of the invention, at least one polycarboxylic acid is added to the filter cake, during or after the liquefaction operation

The invention relates to a process for preparing a precipitated silica, to precipitated silicas, and to uses thereof. The process of the invention generally includes reacting a silicate with an acidifying agent, so as to obtain a suspension of precipitated silica; filtering the precipitated silica to obtain a filter cake; subjecting the filter cake to a liquefaction operation to form a second filter cake; and drying the second filter cake. In the process of the invention, at least one polycarboxylic acid is added to the filter cake, during or after the liquefaction operation.

The invention relates to a process for preparing a precipitated silica, to precipitated silicas, and to uses thereof. The process of the invention generally includes reacting a silicate with an acidifying agent, so as to obtain a suspension of precipitated silica; filtering the precipitated silica to obtain a filter cake; subjecting the filter cake to a liquefaction operation to form a second filter cake; and drying the second filter cake. In the process of the invention, at least one polycarboxylic acid is added to the filter cake, during or after the liquefaction operation.

The invention discloses a preparation method of high-absorptivity silica as lutein carrier. The method includes adding sodium silicate into a synthesis kettle, introducing steam for heating while stirring, adding water, stirring for reaction to obtain a reaction substrate A, and adding sulfuric acid to the reaction substrate A to obtain reaction solution B; simultaneously adding sulfuric acid and sodium silicate into the reaction solution B, performing synthesis reaction for a given period of time, stopping feeding of sodium silicate, adding sulfuric acid only for post-acidification, and aging to obtain dilute slurry D; and filtering the dilute slurry D, washing, slurrying, drying and packaging to obtain silica microspheres as lutein carrier. The invention accurately controls each process so that the prepared high-absorptivity silica as lutein carrier has high adsorption and good dispersibility and flowability after adsorbing lutein.

The invention discloses a preparation method of high-absorptivity silica as lutein carrier. The method includes adding sodium silicate into a synthesis kettle, introducing steam for heating while stirring, adding water, stirring for reaction to obtain a reaction substrate A, and adding sulfuric acid to the reaction substrate A to obtain reaction solution B; simultaneously adding sulfuric acid and sodium silicate into the reaction solution B, performing synthesis reaction for a given period of time, stopping feeding of sodium silicate, adding sulfuric acid only for post-acidification, and aging to obtain dilute slurry D; and filtering the dilute slurry D, washing, slurrying, drying and packaging to obtain silica microspheres as lutein carrier. The invention accurately controls each process so that the prepared high-absorptivity silica as lutein carrier has high adsorption and good dispersibility and flowability after adsorbing lutein.

A precipitated silica is provided having high compatibility with stannous and fluoride ions and good balance of abrasion properties. A precipitated silica characterised by a CTAB surface area S.sub.CTAB comprised between 5 and 50 m.sup.2/g; an abrasion value Hm between 3.5 and 14.0 μm; and a stannous ion compatibility of at least 40%.