| abstract |
(57) [Summary] [Objective] To provide a hydrated silicic acid having a high pore volume and a fine particle size, and a method for producing the same. [Constitution] (1) Hydrated silicic acid obtained by neutralizing an aqueous solution of sodium silicate with a mineral acid and having an oil absorption of 250 to 350 ml / 100. g, total pore volume 4.0-6.0cc / g, average pore radius 200 -400 angstroms and average particle size of 3.0-15 μm by laser method, 2.0-4.0 μm by Coulter method or 0.3-3 by centrifugal sedimentation method. Hydrated silicic acid with particle properties in the range of 5 μm. (2) Wet grinding treatment by strong shearing during the aging period by adding 30 to 50% of the neutralization equivalent of mineral acid to sodium silicate having a silica concentration of SiO 2 of 6 to 10 wt% at a temperature of 70 ° C or less. The second step of adding and aging the remaining amount of mineral acid above the temperature of the previous step to precipitate the total amount of silica, and further adding mineral acid to adjust the pH of the slurry to the range of 5 to 3. A method for producing hydrated silicic acid, which comprises the third step of adjusting. |