| 摘要 |
PURPOSE:To enable a high-speed copying machine to be used by incorporating magnetic toner particles specified in the particle diameter distribution, a fine inorganic powder having a BET specific surface area of 40 - 400m<2>/g by adsorption of nitrogen, and a ferroelectric substance having a BET specific surface area of 0.5 - 30m<2>/g. CONSTITUTION:The negatively chargeable insulating magnetic toner contains the magnetic toner particles of <=5mum diameter in an amount of 17 - 80 number %, those of 6.35 - 12.7mum diameter in an amount of 5 - 50 number %, and those of >=16mum diameter in an amount of <=2.0 volume %, and it has a volume average particle diameter of 4.5 - 9mum, and the particle diameter distribution of the magnetic toner particles of <=5.0mum diameter satisfies expression I in which N is the number % of the magnetic toner particles of <=5mum diameter, V is the volume 5% of them, k is a positive number of 4.5 - 6.5, and N is that of 17 - 80, and the toner comprises the magnetic toner particles and the fine inorganic powder having a specific surface area of 40 - 400m<2>/g, and the ferroelectric substance having that of 0.5 - 30m<2>/g, thus permitting the obtained developer to be used for high-speed copying machines. |
