HYDROPHILIC SILICON DIOXIDE AS FILLING AGENT FOR SILICONE RUBBER COMPOSITIONS Russian patent published in 2014 - IPC C01B33/193 

FIELD: chemistry.

SUBSTANCE: invention can be applied in chemical industry. Precipitated silicon dioxide is obtained by interaction of alkali metal silicate and/or alkali earth metal silicate and acidifying reagent at temperature equal from 80 to 95°C, for from 60 to 90 min. After that, precipitated suspension is acidified and subjected to ageing for 5-50 minutes, filtered, washed and dried. Value Y, characterising concentration of alkali metal ion in reaction mixture solution, is supported for precipitated suspension at constant value, equal from 10 to 30, and deviates by not more than 3% from the initial Y value. Precipitated silicon dioxide has BET surface area from 185 to 260 m²/g; surface area, equal from 100 to 160 m²/g; BET/CTAB ratio, equal from 1.2 to 2.6; electric conductivity, equal less than 250 (µS); average size of particles d₅₀, equal from 5 to 25 mcm; and tap density, equal from 50 to 150 g/l.

EFFECT: claimed silicon dioxide is suitable for application in compositions of silicone rubber RTV-1, RTV-2, HTV and LSR to thicken and strengthen compositions.

15 cl, 4 tbl