Nippon Aerosil Co., Ltd.

Degussa Aktiengesellschaft

Nippon Aerosil Co., Ltd. (nac)

Nippon Aersoil Co., Ltd.

Takeyoshi Shibasaki

Hirokuni Shirono

Naruyasu Ishibashi

Masamichi Murota

Kai Schumacher

Eiji Komai

Hauke Jacobsen

Matthias Rochnia

Ralph Brandes

Yuki Amano

Akira Inoue

Rikio Saito

Kazuyoshi Honda

Kazuhisa Konno

Pyrogenically produced silicon dioxide powder in the form of aggregates of primary particles having a BET surface area of 90&#xb1;15 m/g, wherein the aggregates display an average surface area of 10000 to 20000 nm, an average equivalent circle diameter (ECD) of 90 to 130 nm and an average circumference of 1000 to 1400 nm. It is produced by a pyrogenic process in which silicon tetrachloride and a second silicon component comprising HSiCl, HSiCl, HSiCl, CHSiCl, (CH)SiCl, (CH)SiCl and/or (n-CH)SiClare mixed with primary air and a combustion gas and burnt into a reaction chamber, secondary air also being introduced into the reaction chamber, and the feed materials being chosen such that an adiabatic flame temperature of 1810 to 1890&#xb0; C. is obtained. Dispersion containing the pyrogenically produced silicon dioxide powder.

Pyrogenically produced silicon dioxide powder and dispersion thereof

A high dispersible hydrophobic fine silica powder can be made, wherein the silica powder has hydrophobicity of more than 50%, triboelectrostatic charge of more than &#x2212;500 &#x3bc;C/g, decomposition rate of an organic group on the powder surface of less than 15%, transmittance of a 5% alcoholic dispersion liquid of more than 40% preferably, and a specific surface area of more than 200 m/g. This high dispersible hydrophobic fine silica powder can be made by mixing a hydrophobic agent comprising a volatile organic silicon compound in the gas state with a fine silica powder in a fluidized bed type reaction vessel at the time of a hydrophobic treatment, and controlling a gas flow rate to more than 5.0 cm/sec at the time of this mixing.

Highly dispersible fine hydrophobic silica powder and process for producing the same

A surface modified inorganic oxide powder is provided, which includes inorganic oxide particles having a surface modified with a mixed solution, which includes an organopoly-siloxane and a silane compound, in the presence of an acid or a base.

Surface-modified inorganic oxide powder, process for producing the same, and use thereof

The amorphous-silica particle having 0.1&#x2013;0.7 &#x3bc;m of the average particle diameter, 5&#x2013;30 m/g of the specific surface area, less than 40% of the dispersion coefficient, and 20 &#x3bc;C/mof the absolute value of the triboelectrostatic charge, can be obtained, by setting flame temperature to more than melting point of silica, raising the silica concentration in a flame, and staying the generated silica particle in the flame for a short time to be grew up. Since this silica particle has a particle shape being near a true sphere, and a particle size of said particle is remarkably uniform, so it is suitable for a filler of a semiconductor sealing agent or various materials, etc. In addition, since said particle has strong electrification, it is also suitable for an outer or an inner additional agent of a toner for an electronic photograph, a photo conductor material for a electronic photograph, and a material of an electric charge transportation layer, etc.

Amorphous, fine silica particles, and method for their production and their use

Firstly, a powder matrix is kept in a fluent state, said powder matrix consisting of a first oxide having an absorbed water amount of 0.1 to 50%, an averaged particle diameter of 0.005 to 0.5 &mgr;m and a surface hydroxyl group number of 0.1 to 25 &mgr;mol/m . Then, one or both of a halide and an alkoxide including metal or semi-metal identical with or different from the metal or semi-metal constituting said first oxide is allowed to contact with said powder matrix kept in the fluent state, by means of an inert carrier gas, and then they are heated at a temperature of from 25 to 800&deg; C., to thereby coat said powder matrix by a coating layer consisting of a second oxide. Further, a reaction by-product consisting of one or both of a hydrogen halide or an alcohol generated by said contacting is heated at a temperature of from 200 to 1000&deg; C. within the inert carrier gas to thereby eliminate the reaction by-product.

Oxide powder and method for preparing the same, and product using the same

An ultrafine particle silicon dioxide which comprises silicon dioxide powders in the range of ultrafine particles having a BET specific surface area of 350 m /g or more and has a ratio of BET/CTAB specific surface areas of 0.6 to 1.1, a number average of primary particle diameters of 1 to 20 nm, void volume measured with a mercury porosimeter of 0.1 to 1.0 ml/g and linseed oil absorption of 350 to 600 ml/100 g. According to the present invention, the ultrafine particle silicon dioxide can provide various kinds of polymers with excellent mechanical strength and transparency as a filler.

Ultrafine particle silicon dioxide and process for producing the same

By treating metal oxide fine particles having a specific surface area of 5 to 500 m.sup.2 /g with a silane coupling agent and then further treating the fine particles with a reactive group-terminated organopolysiloxane, the organopolysiloxane is stably bonded to the surface of the powder particles, to thereby improve stability of the modifying effect against the elapse of time and durability.

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Yokkaichi, Japan

Takeyoshi Shibasaki