A precipitated silica with the following physicochemical properties:
BET surface area
35 m2/g to 350 m2/g
BET/CTAB surface area ratio
0.8 to 1.1
Pore volume, PV
1.6 ml/g to 3.4 ml/g
Silanol group density
3 ml/(1.5 g) to 9.5 ml/(1.5 g)
(V2 = NaOH consumption)
Average aggregate size
250 nm to 1500 nm
CTAB surface area
30 m2/g to 350 m2/g
DBP value
150 ml/100 g to 300 ml/100 g
V2/V1 by Hg porosimetry
0.19 to 0.46
DBP/CTAB
1.2 to 3.5
is produced by reacting alkali silicate with mineral acids at temperatures of
60 C. to 95 C. while maintaining a pH of 7.5 to 10.5 and continuously
stirring, continuing the reaction to a solids concentration in the precipitation
suspension of 90 g/l to 120 g/l, adjusting the pH value to a value of less than
or equal to 5, filtering out, washing, drying and optionally grinding or granulating
the precipitated silica. The precipitated silica is used as a filler in vulcanizable
rubber compounds and vulcanizates.