Degussa Aktiengesellschaft

Mattias Neumueller

Robert Kuhlmann

Heinz Esch

Ralf Rausch

Karin Otto

Precipitated silica which has a BET surface area of 10-130 m.sup.2 /g, a CTAB surface area of 10-70 m.sup.2 /g , an average particle diameter of 5-20 .mu.m, a Cu abrasion value in a 10% glycerol dispersion of 4-50 mg and thickening behavior in a CMC solution (20% dispersion) of 300-3500 mPa.multidot.s, is produced by simultaneously adding alkali silicate (weight modulus SiO.sub.2 :alkali oxide=2.5-3.9:1) and a mineral acid to an initial amount of water which has been adjusted to a pH value of 7.0 to 9.9 or 10.0 to 10.7 by the addition of water glass, holding the pH value constant between 7.0 and 9.9 or 10.0 to 10.7 during addition, wherein the initial precipitation temperature is 50.degree.-90.degree. C. and an increase in viscosity occurs after at most 25% of the duration of precipitation, adjusting the pH value to .ltoreq.6, preferably 3.5, once a silica content of greater than 120 g/l or greater than 150 g/l, preferably .gtoreq.160 g/l to 240 g/l, has been reached, separating the solid by filtration, washing, drying and grinding it. The precipitated silica may be used as an abrasive and/or thickening component in toothpastes.

Growing community of inventors

Hasselroth, Germany

Mattias Neumueller