| 摘要 |
PURPOSE:To obtain an external additive with which electrification of the toner to be used can be controlled and the toner admix property can be improved, by using surface-treated inorg. fine particles treated with the amino group-contg. coupling agent by a specified proportion to a hydrophobic treating agent. CONSTITUTION:The external additive consists of surface-treated inorg. fine particles treated with a hydrophobic treating agent and amino group-contg. coupling agent which compounded by <=0.1 pt.wt to 1 pt.wt. of the hydrophobe. This additive is added to the toner to obtain a developer for electrophotography. As for the inorg. fine particles, such a powder is used that can be negatively electrified by itself or by triboelectricity with iron powder. For example, metal oxides such as silica, titanium oxide, zirconium oxide, etc., can be used. As for the hydrophobic/treating agent, silane couplingagent, aluminum coupling agent, zircoaluminate coupling, etc., are used. As for the amino group-contg. coupling agent, org. silicon compds. having amino groups are preferably used.
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