Process for preparing precipitated silica

US4857289A · kind A · utility

Assignee

• Degussa AG · DE

Inventors

• Peter Nauroth · Wesseling, DE
• Robert Kuhlmann · Lechenich, DE
• Gunter Turk · Hanau, DE
• Adam Becker · New York, US

Key dates

• Filing date: May 5, 1988
• Grant date: Aug 15, 1989
• Expiry date: May 5, 2008

Classification

• Technology area (CPC C): Chemistry; Metallurgy
• CPC primary: C01P2006/90
• WIPO field: Pharmaceuticals
• WIPO sector: Chemistry

Abstract

Precipitated silicas which have the following physicochemical characteristics, depending on the manner in which they are milled: ______________________________________ Pendulum roller mill Jet mill ______________________________________ BET m.sup.2 /g 15-110 15-110 surface area Tamped g/l 150-750 90-650 den- sity Cu abrasion in 10% mg 5-30 5-30 strength glycerol dispersion Lightness % 86-96 90-96 value Particle size dis- as in FIG. 1 as in FIG. 2 tribution curve determined by a Coulter Counter "ALPINE screen retain- % by <1.5 <0.1 ings" >63 .mu.m weight Viscosity of a 30% mPa.s 30,000 to 60,000 strength dispersion in a 1:1 glycerol/water mixture (Brookfield RTV, Sp5) ______________________________________ are prepared by diluting a precipitated silica original suspension obtained according to German Published Application DAS 1,467,019 and simultaneously adding alkali metal silicate solution, sulfuric acid and water while keeping the pH constant between 7 and 9. The precipitated silica is then filtered off, washed, dried and milled using a pendulum roller mill or a jet mill. Because of their abrasiveness, the precipitated silicas can be employed as cleansing and abrasive agents and,…