Cerium containing precipitated silica, process for its production

Abstract

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 m.sup.2 /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.degree. C. .mu.s 500 Packed density according to DIN 53 194 g/l 80 .+-. 40 CeO.sub.2 -content, based on the material dried for 2 hours at 105.degree. 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.

Dependencies are inferred from the claim text.