MAGNETIC TONER

摘要

PURPOSE: To obtain such a magnetic toner that high picture quality with high image density and low fog in the base is obtd. and filming can be prevented by using a magnetic toner containing inorg. fine particles and silica fine particles. CONSTITUTION: This magnetic toner is used for an electrophotographic method using an electrostatic latent image holding body 1 which houses a fixed magnet 2 and rotates and a toner recovering electrode roller 8 having a magnet 9 inside. The toner consists of at least a binder resin, magnetic material and external additive. The external additive consists of at least inorg. fine particles and hydrophobic silica fine particles. The inorg. fine particles are obtd. by hydrothermal synthesis and has 0.05-4μm average particle diameter and 0.1-40m<2> /g BET specific surface area by adsorption of nitrogen. The hydrophilic silica fine particles are subjected to surface treatment with silicone oil and has 50-350m<2> /g BET specific surface area by adsorption of nitrogen. By this method, a magnetic toner showing high negative electrification property is obtd. and an image of high picture quality with sharp characters can be obtd.