Canon Kabushiki Kaisha

Atsushi Kubo

Masanori Ito

Keita Nozawa

Kiyokazu Suzuki

Tomoaki Igarashi

Hitoshi Kanda

Yoshinori Tsuji

Takeshi Tsujino

Minoru Ohmura

An electrophotographic toner is formed as a blend of toner particles and external additives. The external additives include (1) first inorganic fine particles having an average primary particle size of 80-800 nm of oxide of a metal selected from the group consisting of titanium, aluminum, zinc and zirconium, (2) second inorganic fine particles other than silica having an average primary particle size of below 80 nm and (3) silica fine particles having an average primary particle size of below 30 nm. As a result, the toner can be made free from difficulties, such as melt-sticking onto an image-bearing member in a low humidity environment, roughening of halftone images in a low humidity environment, toner blot-down after storage at high temperatures or in continuous image formation on a large number of sheets, fog in continuous formations of images of low color area percentage in a low humidity environment, and re-transfer in multi-color image formation. Thus, the toner is suitably used in a multi-color image forming system.

Toner, process for producing a toner, image forming method and image forming apparatus

A process for producing a toner. The process has the steps of dispersing a fine-particle colorant in a liquid monomer mixture containing at least a liquid polymerizable monomer, dispersing the resulting colorant-dispersed liquid monomer mixture in an aqueous dispersion medium to form particles of a polymerizable monomer composition, and polymerizing polymerizable monomers present in the particles in the aqueous dispersion medium to form toner particles. In the dispersion step, a media particle agitation type wet-dispersion machine is used as a dispersion means. The dispersion machine has a cylindrical vessel having a first wall surface having a liquid-feed opening and a second wall surface having a liquid-discharge opening. The vessel is inside provided with an inner chamber and an outer chamber which are partitioned with a cylindrical separator having slits, a rotor set in the inner chamber rotatably by the rotary drive motion of a drive shaft, and a plurality of spherical media particles held in the inner chamber.

Process for producing toner

Growing community of inventors

Ibaraki-ken, Japan

Atsushi Kubo