| 摘要 |
PROBLEM TO BE SOLVED: To provide hydrophobized silica powders and the like suitable for an external additive for an electrophotographic toner and the like and excellent in the environmental stability of toner electrification quantity. SOLUTION: Surface-hydrophobized silica powders by a dry method are characterized by that silica powders by the dry method are surface-treated with hexamethyldisilazane for hydrophobization and that the ratio A/B of a single silanol group integration value A to a siloxane integration value B is less than 0.8. It is favorable that the ratio A/B of the integration value A to the integration value B is less than 0.7, silica powders are produced by the dry method and a specific surface area by a BET method is 5-500 m<SP>2</SP>/g. COPYRIGHT: (C)2007,JPO&INPIT
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