Cerium containing precipitated silica, process for its production

摘要

Cerium containing precipitated silica is disclosed as well as a process for its production as well as compositions hardenable to elastomers which contain the cerium containing precipitated silica. The precipitated silica -BET-surface area according -to DIN 66 131 m2/g 140 +/- 40 -Loss on drying according -to DIN 55 921 Wt.-% 2.0-4.0 -Loss on ignition according -to DIN 55 921 Wt.-% 2.5-12.5 -pH-according to DIN 53 200 3.0-7.0 -Conductivity in 4% aqueous -dispersion at 20 DEG C. mu s 500 -Packed density according -to DIN 53 194 g/l 80 +/- 40 -CeO2-content, based on the -material dried for 2 -hours at 105 DEG C. Wt.-% 0.3-50 -Sieve residue according -to Mocker 45 mu m -(DIN 53 580) Wt.-% 0.2 - They are prepared by adding a cerium (IV) salt solution to the original precipitated suspension of a precipitated silica. The compositions produced with the cerium containing precipitated silica hardenable elastomers based on diorganopolysiloxanes exhibit excellent heat stability. Additionally, the cerium containing precipitated silica acts as a fire retardant agent.