Minolta Company, Ltd.

Yutaka Tsujishita

Akihiro Nakamura

Choichiro Tanigawa

Kinya Sonoda

Katsuji Nagasawa

Yasunori Sakuda

An air classifying system that can produce toner particles having a desired particle size is disclosed. The air classifying system contains a supplying pipe for supplying raw materials; a truncated cone-like breather pipe that has a ratio of minimal opening sectional area S.sub.1 to a maximum opening sectional area S.sub.0 being between 0.2 and 0.5, and an angle .theta. formed between axis and generatrix being between 10.degree. and 35.degree.; a classifying means for classifying the raw materials supplied through the supplying pipe; and an air flow-generating means for generating air-flow for transporting the raw materials in the classifying system.

Air classifier with specified truncated cone-like breather pipe

The present invention relates to a toner comprising toner particles which include at least a colorant, a binder resin, particles of metal oxide having a BET specific surface area of 80.about.300 m.sup.2 /g, and an organic boron compound represented by the structural formal (I) below. ##STR1## (Where Z is a residue forming a ring with an adjacent oxygen atom and carbon atom, X is a cation, and n is an integer of either 1 or 2.) The present invention further relates to a method of manufacturing a toner comprising a process of mixing at least a colorant, a binder resin, particles of metal oxide having a BET specific surface area of 80.about.300 m.sup.2 /g, and an organic boron compound represented by the structural formal (I); a process of melting and kneading the obtained mixture; a process of cooling the kneaded mixture; a process of pulverizing said mixture to produce particles having a predetermined particles size; and a process of classifying said pulverized particles to obtain toner particles which are removed undesired small toner particles.

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Takarazuka, Japan

Yutaka Tsujishita