Precipitated silicas with a particular pore size distribution

摘要

Precipitated silicic exhibiting physical-chemical properties such as relative width (gamma ) of the pore size distribution of 4-10 (g nm)/ml, sears number (V2) of 28-40 ml/(5 g), sears number (V2/CTAB) ratio of 0.18-0.28 ml/(5 m 2>) and cetylammonium bromide (CTAB) surface area of 100-200 m 2>/g. Independent claims are included for: (1) the preparation of precipitated silicic acid, comprising (a) subjecting an aqueous solution of alkali or alkaline-earth silicate and/or an organic or an inorganic base, where the submittal exhibited an alkali number of 20-40, (b) adding alkaline and/or alkaline-earth silicate and acidifying agent into the submittal under intensive stirring at 55-85[deg]C to increase viscosity of the solution, (c) terminating the reaction after the addition that takes place for 35-85 minutes, preferably after reaching the temperature of step (b), (d) again adding alkali and/or alkaline-earth silicate and an acidifying agent under agitation at 55-85[deg]C to attain a solid content of 90-140 g/l, (e) adjusting pH of the solution to 2.5-5 by adding the acidifying agent and (f) filtering and drying; (2) vulcanizable rubber mixture and vulcanizate comprising the precipitated silicic acid as filler; and (3) a tire comprising at least a precipitated silicic acid.