| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide an external additive for toner which causes no reaction and no interaction with an organic photoreceptor and consequently causes no deterioration and no crack of the photoreceptor, and which has excellent flowability and consequently causes no sticking of the toner to the photoreceptor and consists of fine silica particles. SOLUTION: The electrostatic charge image developing toner external additive is distinguished by being consisting of spherical hydrophobia fine silica particle which is obtained by introducing a R13SiO1/2 unit (in which R1 is univalent hydrocarbon group of 1-6C having substituents of the same kinds or different kinds or having no substituent) on a surface of a hydrophilic fine silica particle constituted of SiO2 unit, which satisfies conditions (i) and (ii) described below, of which average grain size of primary particles is 0.01 to 5μm. (i) When the fine silica particles are blended with an organic compound which is liquid at room temperature and has 1 to 40 F/m dielectric constant at 5:1 weight ratio and are shaked, the fine silica particles uniformly disperse in the organic compound. (ii) When the fine silica particles are kept at 100 deg.C for 2 hours after evaporating methanol by an evaporator under heating from a dispersion obtained by dispersing the fine silica particles into methanol, ratio of primary particle quantity left as the primary particle to primary particle quantity present at first is >=20%.</p> |
