POSITIVE CHARGE TYPE TONER FOR DEVELOPING ELECTROSTATIC LATENT IMAGE

摘要

PROBLEM TO BE SOLVED: To obtain a positive charge type toner for developing an electrostatic latent image capable of attaining a remarkably prolonged service life of a developer. SOLUTION: Two or more additives are mixed and added to toner particles used for a two-component developer after it is mixed with a carrier and containing at least a colorant and a binder resin to obtain the objective positive charge type toner. The additives are at least negative charge type inorganic particles A of 80-800 nm number average diameter including <=20% by number of particles of >=1,000 nm diameter, and positive charge type inorganic particles B of 5-50 nm number average diameter. The release rates (d) of the inorganic particles A and B under the application of a certain level of ultrasonic energy to the toner are 20-50 wt.% each of the weight of the added particles. The weight ratio of the inorganic particles A to B contained in the toner is 2.5:7.5 to 8.5:1.5.