CAKE OF EASILY DISPERSIBLE PRECIPITATED SILICA AND PROCESS FOR PRODUCING THE SAME

摘要

A silica cake formed of easily dispersible precipitated silica having small primary particle size is provided, from which highly transparent silica dispersion can be effectively obtained. This silica cake is <Bold>characterized by</Bold> being a cake of precipitated silica having BET specific surface area of at least 220 m<Sup>2</Sup>/g, and when it is dispersed in ion-exchange water to provide an aqueous dispersion of the silica of 5% by weight in concentration and further diluted to reduce the silica concentration to 1.5% by weight, the dispersion having a light-scattering index (n-value) of at least 2. This silica cake can be obtained by simultaneously adding an alkali silicate and a mineral acid to a reaction liquid whose pH is being maintained at a fixed value within a range of 7.5 - 11.5 and whose temperature is being maintained at not lower than 90°C, whereby forming precipitated silica through their reaction, and separating said precipitated silica from the reaction liquid in wet state.