Process for the preparation of precipitated silica.

摘要

Precipitated silica having a BET surface area of 10-130 m<2>/g, a CTAB surface area of 10-70 m<2>/g, a mean particle diameter of 5-20 mu m, a Cu abrasion in 10% strength glycerol (glycerine) dispersion of 4-50 mg and a thickening behaviour in CMC solution (20% strength dispersion) of 300-3500 mPa.s is prepared by simultaneously adding alkali metal silicate (weight ratio SiO2: alkali metal oxide = 2.5-3.9:1) and a mineral acid to an initial charge of water which has been adjusted to a pH of from 7.0 to 9.9 or from 10.0 to 10.7 by addition of water, keeping the pH constant between 7.0 and 9.9 or 10.0 and 10.7, with the initial precipitation temperature being 50-90 DEG C and a viscosity increase commencing at the latest after 25% of the precipitation time, setting the pH to /= 160 g/l to 240 g/l, separating off the solid by filtration and washing, drying and milling it. The precipitated silica can be used as abrasive and/or thickening component in toothpastes.