Method for producing modified precipitated silica and a composition containing the same
Modified precipitated silica is produced in a one pot synthesis by forming precipitated silica and modifying with an organosiliconate. The modified precipitated silica is washed following preparation, affording a modified precipitated silica with low levels of ionic substances.
1. A process for modifying precipitated silica to produce a modified precipitated silica, comprising:
i) modifying the precipitated silica in a reaction mixture comprising
1) acid,
2) at least one of precipitated silica and/or [SiO 4/2 ] starting material(s), and
3) at least one organosiliconate as a modifying agent,
wherein modifying is effected during or directly after production of the precipitated silica,
ii) filtering and washing the reaction mixture, and
iii) optionally, drying the reaction mixture,
wherein the [SiO 4/2 ] starting materials comprise alkoxysilanes, alkali metal silicates, or mixtures thereof.
2. The process of claim 1 , wherein the modifying agent is added at a constant dosage rate.
3. The process of claim 1 , wherein the temperature is kept constant during process step i).
4. The process of claim 1 , wherein the pH is kept constant during process step i).
5. The process of claim 1 , wherein the modifying agent is added to the reaction mixture in parallel with the acid and the [SiO 4/2 ] starting materials.
6. The process of claim 1 , wherein the modifying agent is added to the reaction mixture at a different time.
7. The process of claim 1 , wherein the organosiliconate is a methylsiliconate.
8. The process of claim 1 , wherein the process is effected in a batchwise operation.
9. The process of claim 1 , wherein the process is a continuous operation.