| 摘要 |
A magnetic black toner comprising magnetic black toner particles containing at least a binder resin and a magnetic material. The toner has a weight-average particle diameter of from 5 mum to 12 mum, and the toner has, in its particles of 3 mum or more in diameter, at least 90% by number of particles with a circularity of 0.900 or more and has an average circularity of from 0.940 to 0.970. The magnetic material comprises iron oxide particles which have an average particle diameter of from 0.10 mum to 0.30 mum, contain titanium or a titanium compound in an amount of from 0.3% by weight to 1.5% by weight in terms of titanium, based on the total weight of the iron oxide particles, and have the ratio of the proportion of FeO to the total Fe content in 10% by weight from the particle surface, A%, to the proportion of FeO to the total Fe content in the remainder 90% by weight, B%, which satisfies the expression: 0.7<=A/B<=1.0. Also, an inorganic fine powder is externally added to the toner particle surfaces.
|
