The Aerosil 200 silica used in accordance with the invention

The Aerosil® 200 silica used by the invention, with a BET surface area, differs from the known Aerosil® 300, which has a surface area of 300 m2/g, not only in the surface size but also in the average primary particle size. The Aerosil® 300 has an average primary particle size of 7 nm. Based on these differences, these silicas have different performance properties. The fumed silica of the invention contains no hydrophobic fractions. Despite this, the silica of the invention shows no propensity to agglomerate. The goniometer value is below 30. The fumed silica of the invention can be used as a filler in silicone rubber compounds. Silicone rubber compounds and fumed silica (AEROSIL®) used in silicone rubber compounds are known (Ullmann's Encyclopaedia of Industrial Chemistry, Volume A 23, Rubber, 1, 221 ff.; Rubber 3, 3.6 ff.; Volume A 24, Silicones 57 ff. 1993). Fumed silica is used for its excellent thickening effect (thixotropic) in silicone sealants; this is desirable in the context of use as a jointing compound. Where, however, the silicone rubber compounds are to be used as coating materials, a low level of thickening is desired (U.S. Pat. No. 6,268,300). Of decisive importance in both cases is the optical quality of the surface of the silicone vulcanizates. Therefore, it is an object of the present invention to provide silicone rubber compounds that exhibit an optically high-grade surface after vulcanization through fumed silica as filler. If you are looking for high quality, high purity, and cost-effective Fumed silica, or if you require the latest price of Fumed silica, please feel free to email contact mis-asia.