| 摘要 |
PROBLEM TO BE SOLVED: To provide a production method by which hydrophobed associated silica microparticles particularly useful as an external toner additive are obtained.SOLUTION: A method for producing associated silica in which two or more primary particles having an average particle diameter within a range of 5-500 nm are associated includes agglomerating hydrophobic spherical silica microparticles having a carbon content of 2-5 mass%, an alkoxy group content of 0.3-10 mass% and an average particle diameter of primary particles of 0.01-200 nm at a temperature of 100-500°C under a humidified atmosphere, wherein the hydrophobic spherical silica microparticles are obtained by a hydrophobing treatment of hydrophilic silica comprising SiOunits obtained by hydrolyzing and condensing at least one compound selected from the group consisting of a tetraalkoxysilane represented by the formula (1): Si(OR)(1) (Ris an alkyl group) and a partial hydrolysis-condensation product thereof, wherein the hydrophobizing treatment is performed by introducing an RSiOunit (Ris a monovalent hydrocarbon group) into the surface of the hydrophilic silica and further introducing an RSiOunit (Ris a monovalent hydrocarbon group). |
