Verfahren zur Herstellung oberflaechenmodifizierter, Kieselsaeure enthaltender Fuellstoffe

摘要

Finely divided silica e.g. diatomaceous earth, precipitated silica, silica aerogel and fume silica s surface modified by treating with a mixture of (1) a liquid cyclic siloxane, and (2) an organic silicon compound of general formula where R is an alkyl group of not more than 3 carbon atoms R1 and R11, which may be the same or different, are phenyl groups, alkyl or alkoxy groups containing not more than 3 carbon atoms; n is 0, 1, 2 or 3 and not more than two aryl groups are attached to any one silicon atom. The mixture, which may contain from 5% to 95% of the liquid cyclic siloxane, can be added to the silica, in an amount from 5% to 40% by weight of the silica, by any suitable method provided the treating medium is evenly distributed throughout the total bulk of the silica. The preferred method is to form the silica into a fluidized bed and introduce the mixture via an atomizer at a point well below the apparent surface of the bed usually at ambient temperature. The product is used as a filler for organopolysiloxane elastomers. The cyclic siloxanes (1) mentioned are octamethyl cyclo tetrasiloxane, decamethyl cyclo pentasiloxane, duodecamethyl cyclohexasiloxane and tetramethyl tetravinyl cyclo-tetrasiloxane, and the compounds (2) are exemplified as diphenyl dimethoxy silane, diphenyl-diethoxy silane, diphenyl di-n-propoxy silane, phenyl trimethoxy silane, phenyl methyl dimethoxy silane, dimethyl diphenyl dimethoxy disiloxane, diphenyl tetramethoxydisiloxane, and dimethyl triphenyltrimethoxy trisiloxane.ALSO:A filler for organo-polysiloxane elastomers is produced by treating finely divided silica (particle size not greater than 10 micron) with a mixture of (1) a liquid cyclic siloxane, and (2) an organic silicon compound of the general formula where R is an alkyl group of not more than 3 carbon atoms, R1 and R11, which may be the same or different, are phenyl groups, alkyl or alkoxy groups of not more than 3 carbon atoms; n is 0, 1, 2, or 3, and not more than two aryl groups are attached to one silicon atom. The cyclic siloxane is present in amounts of from 5 to 95%, preferably 40-60% by weight of the mixture and the silica is usually treated (see Group III) with from 5 to 40% preferably 10-25% of its own weight of the mixture. Samples of elastomer compositions were prepared by mixing various amounts of filler with 100 parts by weight of a linear methyl vinyl polysiloxane and one part of red iron oxide. The compositions can be stored, for periods up to eight weeks and after storing freshen easily to mix with 0,5 parts of dichlorbenzoyl peroxide and cure by pressing at 400 lbs. per square inch at 115 DEG C. for 10 mins. The compositions are then given a further heating in air.