MAGNETIC TONER

摘要

A magnetic toner capable of exhibiting stable changeability regardless of environmental change is formed of magnetic toner particles each comprising at least a binder resin, an iron oxide and a sulfur- containing polymer, and inorganic fine powder blended with the magnetic toner particles. The magnetic toner is also provided with good developing performance and high transferability by satisfying a weight-average particle size (D4) of 3 - 10 .mu.m, an average circularity of at least 0.970, and a magnetization of 10 - 50 Am2/kg (emu/g) at a magnetic field of 79.6 kA/m (1000 oersted). The magnetic toner is further characterized in that the magnetic toner particles retain carbon in an amount of A and iron in an amount of B at surfaces thereof as measured by X-ray photoelectron spectroscopy, satisfying: B/A < 0.001, and the magnetic toner contains at least 50 % by number of magnetic toner particles satisfying a relationship of D/C ~ 0.02, wherein C represents a projection area-equivalent circle diameter of each magnetic toner particle, and D represents a minimum distance between a surface of the magnetic toner particle and iron oxide particles contained in the magnetic toner particle.