| abstract |
(57) [Problem] To provide a magnetic toner capable of obtaining good developability and durability even in a system for developing at high speed. SOLUTION: In a magnetic toner having at least a binder resin and a magnetic material, the magnetic material contains silicon inside the particle, and the particle surface is coated with a composite iron oxide containing silicon and zinc, From the surface of the magnetic material, the mass ratio Zn / silicon contained in the iron element dissolution rate of 5% by mass was Zn / Si is 0.2 to 0.5, the number average particle diameter by SEM observation is 0.1 to 0.3 μm, and the number average particle diameter D 50 by laser diffraction scattering type particle size distribution measurement is 200 to 1. The magnetic toner has a dielectric loss tangent (tan δ) at 30 ° C. and a frequency of 5.0 × 10 3 Hz of 2.0 × 10 −3 to 1.0 × 10 × 10 nm. It is in the range of 10 -2 . |