Tokuyama Corporation

Tadaharu Komatsubara

Kenichi Ishizu

Yuya Yamano

Hiroshi Kato

Hiroaki Taira

Takayuki Maehara

Yohei Chikashige

Makoto Sato

Masahiro Nakamura

Toru Iwata

Provided is a novel spherical polymethylsilsesquioxane particle having an unprecedentedly large specific surface area ratio. The spherical polymethylsilsesquioxane particle includes a particle main body containing at least: a network structure formed by silicon atoms (n) and oxygen atoms (n) bonded to the silicon atoms (n); a methyl group bonded to at least one of the silicon atoms (n); and an alkoxyl group bonded to at least one of the silicon atoms (n), wherein the spherical polymethylsilsesquioxane particle satisfies the following expression (1): Expression (1) S/S≥8.0, in the expression (1), Srepresents a specific surface area (m/g) measured by a nitrogen adsorption BET one-point method, Srepresents 6/(ρ×D50) and a unit thereof is (m/g), ρ represents a particle density (g/m), and D50 represents a volume-based 50% cumulative diameter (m) measured by a laser diffraction/scattering method.

Spherical polymethylsilsesquioxane particles

A silicone oil-treated silica particle according to the present invention includes a silica particle body and silicone oil. The silica particle body has a BET specific surface area of 70 m/g to 120 m/g. The silica particle body has been surface-treated with the silicone oil. The amount of free silicone oil liberated from the surface of the silica particle body in the silicone oil accounts for 2.0 mass % to 5.0 mass % with respect to the silica particle body. A surface-treated styrene acrylic resin particle, in which 2 parts by mass of the silicone oil-treated silica particle has been added to 100 parts by mass of a styrene acrylic resin particle having a particle size median of 5 &#x3bc;m to 8 &#x3bc;m, has a degree of agglomeration of 18% or less.

Silicone oil-treated silica particles and toner for electrophotography

Provided are a poly alkylsilsesquioxane fine particle having hydrophobicity and having a small particle diameter, an external additive for toner and a dry toner for electrophotography each using the same, and a method of manufacturing a hydrophobized spherical polyalkylsilsesquioxane fine particle. The hydrophobized spherical poly alkylsilsesquioxane fine particle has a mass-based median diameter in a centrifugal sedimentation method within the range of from 0.05 &#x3bc;m to 0.3 &#x3bc;m. The fine particle is produced through, for example, at least a process involving: mixing a raw material solution prepared using an alkyl trialkoxysilane with an alkaline aqueous medium to obtain a polycondensation reaction liquid; mixing the polycondensation reaction liquid with an aqueous solution to obtain a fine particle dispersion liquid; and blending a hydrophobizing agent in the fine particle dispersion liquid.

Hydrophobized spherical polyalkylsilsesquioxane fine particle, external additive for toner, dry toner for electrophotography, and method of manufacturing hydrophobized spherical polyalkylsilsesquioxane fine particle

The present invention relates to a method for producing inorganic oxide particles, comprising at least the following steps of: The inorganic oxide particles obtained by the method of the present invention have high purity and are excellent in flowability.

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Shunan, Japan

Tadaharu Komatsubara