Toyo Ink Manufacturing Company

Toyo Ink Mgf. Co., Ltd.

Tomomi Yamazaki

Hirofumi Iemura

Nobuyuki Yoshimoto

Hirokazu Kambara

A pulverized starting material is supplied quantitatively from a quantitative feederto a first mechanical pulverizerwhere the material is pulverized moderately, the resulting moderately pulverized material is supplied quantitatively from a quantitative feederto a second mechanical pulverizerwhere the material is finely pulverized, and the resulting finely pulverized material is introduced into a coarse-powder classifierto classify coarse powder not smaller than a predetermined particle diameter. The finely pulverized material from which the coarse powder was removed by classification is further classified fine powder not larger than a predetermined size by a fine-powder classifierto produce a classified product, while the separated classified coarse powder is introduced into a returning-powder feeder. The classified coarse powder introduced into the returning-powder feederis again supplied quantitatively to the second mechanical pulverizer, upon which when it is detected that the weight of the coarse powder stored in the returning-powder feederis deviated from a predetermined range, the amount of the returning powder supplied to the second mechanical pulverizeris changed and regulated such that the powder is supplied in the above changed amount. The pulverization conditions in the first and second mechanical pulverizers are established such that the volume-average particle diameter D1 (&#x3bc;m) of the moderately pulverized material obtained by the first mechanical pulverizerand the volume-average particle diameter D2 (&#x3bc;m) of the finely pulverized material obtained by the second mechanical pulverizer satisfy: 3 &#x3bc;m&#x2266;D1&#x2212;D2 &#x2266;6 &#x3bc;m.

Method of producing an electrostatic charge image developing toner

A positively charging dry toner for developing an electrostatic latent image including a nigrosine dye or nigrosine pigment containing 500 ppm or less nitrobenzene and 800 ppm or less aniline as a charge controlling agent. The dye or pigment is prepared by dispersing the nigrosine dye or nigrosine pigment obtained by an usual method in a solvent, adding an oxidizing agent such as bleaching powder to the solvent dispersion to conduct oxidation treatment and, if necessary, removing the solvent by steam distillation.

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Tokyo, Japan

Tomomi Yamazaki