| abstract |
A room temperature crosslinking, one component (RTV 1C) silicone rubber formulation with hydrophobic, silica featuring extremely low water absorption, a high level of whiteness, and fine-tunable, storage-stable rheological properties with a high reinforcing action in the silicone rubber vulcanizate contains A) from 0.5 to 60% by weight of a hydrophobic silica having the following properties: a carbon content of >3.1%; a methanol wettability of >60%; a reflectance of >94%; a BET/CTAB ratio of from >1 to <3; a DBP absorption of <230 g/100 g; a BET surface area of from 50 to 110 m 2 /g; a CTAB surface area of >30 m 2 /g; a water vapor absorption at 30° C. at an ambient humidity of 30 of <1.3; a water vapor absorption at 30° C. at an ambient humidity of 70 of <1.7; and B) 40-99.5% by weight of an organopolysiloxane of the formula n Z n SiR 3−n —O—[SiR 2 O] x —SiR 3−n —Z′ n n wherein each R represents independently alkyl, acetoxy, oxime, alkoxy, amido, aryl or alkenyl radicals, each having from 1 to 50 carbon atoms, each unsubstituted or substituted identically or differently by O, S, F, Cl, Br or I; or R represents independently polystyrene, polyvinyl acetate, polyacrylate, polymethacrylate, or polyacrylonitrile radicals, each having 50-10 000 repeating units; wherein each Z represents independently OH, Cl, Br, acetoxy, amino, amido, amineoxy, oxime, alkoxy, alkenyloxy, acyloxy or phosphate radicals, wherein said acetoxy, amino, amido, amineoxy, oxime, alkoxy, alkenyloxy and acyloxy radicals each have up to 20 carbon atoms; wherein each Z′ represents independently oxime, alkoxy, amido or acetoxy radicals; wherein n is 1-3; and wherein x is 100-15 000. |