Ricoh Company, Ltd.

Osamu Kouzu

Shigeru Emoto

Tomoyuki Satoh

Noboru Kuroda

Masahiro Kawamoto

Nobutaka Kinoshita

Kenichi Uehara

Yasushi Nakamura

Hiroyuki Yoshikawa

Junya Koeda

A method of producing a toner composition, including stirring and mixing toner particles comprising a binder resin, a colorant and a release agent with a charge controlling agent in a fluidizing and stirring mixer comprising a rotor having a stirring blade to fix the charge controlling agent on a surface of the toner particles, wherein the stirring and mixing comprises rotating the rotor at a peripheral speed of from 65 to 120 m/s at an environmental temperature (T) in the fluidizing and stirring mixer, satisfying the relationship,Tg-10&#x3e;T&#x3e;Tg-35(&#xb0; C.), where the Tg represents a glass transition temperature of the binder resin.

Method and apparatus for producing toner for electrophotography

A toner for developing an electrostatic image, including a binder, a coloring agent and a charge controlling agent. When that portion of the toner which has a particle diameter of 5.04 &mgr;m or less accounts for 15-60% of the total number N of the toner, that portion of the toner which provides a number average particle diameter of 4.0 to 4.5 &mgr;m has such a content C1% by weight of the charge controlling agent that gives a ratio of C1/CT of 1.00 to 1.10, where CT is a total amount, in terms of % by weight, of the charge controlling agent in the toner. When that portion of the toner which has a particle diameter of 5.04 &mgr;m or less accounts for 15% or less of the total number N, that portion of the toner which provides a number average particle diameter of 4.2 to 4.8 &mgr;m has such a content C2% by weight of the charge controlling agent that gives a ratio of C2/CT of 1.02 to 1.15.

Toner for developing electrostatic image and process of preparing same

Growing community of inventors

Fuji, Japan

Osamu Kouzu