DEPOSITED SILICIC ACID, PROCESS FOR PREPARATION THEREOF AND VULCANIZABLE RUBBER MIX Russian patent published in 1997 - IPC

FIELD: rubber industry. SUBSTANCE: deposited silicic acid has the following physical and chemical parameters: surface area determined by BET is from 35 to 350 sq.m/g, the BET to STAB surface area ratio is from 0.8 to 1.1, the pore size is from 1.6 to 3.4 ml/g; the silanol group surface area (V₂= NaOH consumption) is from 6 to 20 ml; the average agressete value is from 250 to 1500 nm; the STAB surface area is from 30 to 350 sq.m/g; the DVR index is from 150-350 ml/100 g; the phase V₂/V₁ ratio as measured by mercury porosimetry is from 0.19 to 0.46; and the DVR/STAB ratio as from 1.2 to 2.4. Alkaline silicate is reacted with mineral acids at temperatures ranging from 60 to 95 C with pH value maintained within 7.5-10.5 under constant stirring. Reaction is carried out till concentration of solid in the precipitate suspension reaches from 90 to 120 g/l, pH value is adjusted to zero or less, precipitated silicic acid is washed, dried and optionally crushed or granulated. Precipitated silicic acid is used as filler in vulcanizable rubber mixes and vulcanizates. EFFECT: improved properties of the vulcanizable rubber mix. 5 cl, 6 dwg, 11 tbl