Preparing precipitated silicic acid, used e.g. in elastomer mixture, comprises subjecting aqueous solution of e.g. alkali and/or alkaline-earth silicate, simultaneously adding e.g. alkali and/or alkaline-earth silicate and drying

摘要

Preparation of precipitated silicic acid comprises (a) subjecting an aqueous solution of an alkali- and/or earth alkaline silicate and/or an organic or inorganic base; (b) simultaneously adding an alkali- and/or alkaline-earth silicate and an acidifying agent to increase the viscosity; (c) terminating the reaction after 35-85 minutes; (d) simultaneously adding an alkali- and/or alkaline-earth silicate and an acidifying agent to attain a solid content; (e) stirring the obtained suspension; (f) adjusting the pH by adding the acidifying agent; and (g) filtering and (h) drying. Preparation of precipitated silicic acid comprises: (a) subjecting an aqueous solution of an alkali- and/or earth alkaline silicate and/or an organic or inorganic base, where the subjected mixture exhibits the alkali number of 20-40; (b) simultaneously adding an alkali- and/or earth alkaline silicate under stirring at 55-85[deg]C and an acidification agent to increase the viscosity of the mixture; ( (c) terminating the reaction after the addition of mixture that takes place for 35-85 minutes, preferably after reacting the temperature of step (b); (d) simultaneously adding an 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) stirring the obtained suspension for 1-120 minutes at 80-98[deg]C; (f) adjusting the pH of the solution to 2.5-5 by adding the acidifying agent; (g) filtering; and (h) drying. Independent claims are included for: (1) a precipitated silicic acid exhibiting physical-chemical parameters such as relative width (gamma ) of the pore size distribution of 4-10 (g nm)/ml, Brunauer, Emmett and Teller (BET)-surface 90-320 m 2>/g, cetylammonium bromide (CTAB) surface area of 100-200 m 2>/g, sears number (V2) of 25-40 ml/(5 g) and sears number (V2/CTAB) ratio of 0.18-0.28 ml/(5 m 2>); (2) a precipitated silicic acid, obtained by the above process; (3) a vulcanizable rubber mixtures and vulcanizate comprising the precipitated silicic acid as filler material; and (4) a tire, comprising at least a precipitated silicic acid.