Magnetic toner using magnetic iron oxide particles, magnetic toner for magnetic iron oxide particles and magnetic iron oxide particles composed mainly of particles

摘要

PROBLEM TO BE SOLVED: To obtain magnetic iron oxide particles capable of preventing their dropping from toner particles and imparting good fluidity and uniform antistaticity to the toner by specifying the particle diameter, Si content, particle shape and surface projection number of the magnetic particles. SOLUTION: The magnetic iron oxide particles comprise magnetite particles, contains Si in an amount of 0.9-6.5atom% based on Fe, and has a particle diameter range of 0.05-0.50μm, a crenated shape based on a particulate shape and 2-30 projections on the surface of the particle on a projection chart. The surfaces of the particles are coated with either one of the oxide, hydroxide, hydrous oxide or their mixture of one or more kinds of elements selected from Al, Ti, Mg, Si, Co, Zr, Mn and Zn. The surfaces of the particles are preferably further coated with a hydrophobic treatment agent. When the particles are used for a toner, the particles are preferably used in a particle number rate of =60%.