Finely divided divided precipitated silica having a high structure, process for producing same and its use

Abstract From the Canadian patent

A finely divided precipitated silica having a structure with a BET surface area (DIN 60132) of between 150 and 350 sq.m/g, tamped density (DIN 53194) of between 60 and 120 g/litre, DBP number of between 3.0 and 4.0 ml/g and particle size distribution of at least 70% of 1 to 6 µm. It can be produced by heating a mixture of water and sodium silicate to a temperature of 70 to 80°C while stirring by metered addition of concentrated sulphuric acid until one half of the alkali present is neutralized, by treating the reaction mixture with a shear unit while simultaneously increasing the temperature to 86~5°C, when required, by adding concentrated sulphuric acid at a higher rate during a period of …