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US 8,075,862 B2Granted
Hydrophobic fumed silica and silicone rubber materials containing the fumed silica
AssigneeEvonik Degussa GmbH
InventorsJuergen Meyer, Horst Zeizinger, Mario Scholz, Uwe Ellenbrand
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Abstract
The present invention relates to a hydrophobic, fumed silica which is obtained by milling a fumed silica which has fixed dimethylsilyl and/or monomethylsilyl groups on the surface due to silanization; and to a process for the preparation of the silica according to the invention, and to silicone rubber materials containing the silica according to the invention.
Claims17
A hydrophobic fumed silica obtained by milling a fumed silica with a pinned-disk mill or an air-jet mill, which has fixed thereon at least one of dimethylsilyl and monomethylsilyl groups on a surface due to silanization,
- wherein said hydrophobic fumed silica has
- a grindometer value which is reduced by more than 60% compared with said fumed silica
- a tamped density of 10 to 80 g/l,
- a BET specific surface area of 150 to 200 m2/g,
- an average particle size according to Cilas of 3.0 to 20.0 μm,
- a pH in the range from 4.0 to 5.0, and
- a carbon content of 0.1 to 10% by weight.
4 more elements
Dependencies are inferred from the claim text.