| 摘要 |
PROBLEM TO BE SOLVED: To solve the problem associated with conventional positive charging silica particles in which plus charging is gradually reduced as being used as a toner external additive, due to mechanical stress by repeated contact with a toner for a long time, and due to thermal stress from long storage under a high temperature and high humidity environment, in a developer, and charging of the silica particle returns to minus charging original to the silica, resulting in insufficient long charging stability; and provide a novel positive charging silica particle that is excellent in long charging stability and can maintain stable image characteristics as the toner external additive.SOLUTION: A positive charging silica particle according to this invention is a surface-treated silica particle in which a group including an amino group and a hydrophobic substituted silyl group are introduced to a surface by covalent binding, and at least a part of the surface is coated by a silicon oil.SELECTED DRAWING: None |
