Powdertech Co., Ltd.

Kouichi Shimizu

Yuji Sato

Toshio Honjo

Masahiro Ogata

Kanao Kayamoto

Norio Takei

This invention provides a ferrite carrier for an electrophotographic developer characterized in that a core material is ferrite particle composed of 17.0 to 29.0 mol % of Li.sub.2 O and 71.0 to 83.0 mol % of Fe.sub.2 O.sub.3, exhibits a resistance of 2.5.times.10.sup.8 to 2.5.times.10.sup.9 .OMEGA. when a voltage of 250 V is applied, satisfies the relationship: a.sub.1 -a.sub.2 .ltoreq.1.5 when the resistance (R.sub.1) of the ferrite particle exhibited when a voltage of 250 V is applied thereto is taken as a.sub.1 .times.10.sup.b .OMEGA. and the resistance (R.sub.2) thereof exhibited when a voltage of 1000 V is applied thereto is taken as a.sub.2 .times.10.sup.b .OMEGA. (with the proviso that 1.0.ltoreq.a.sub.1 &lt;10, 0.1.ltoreq.a.sub.2, and b is an integer of 6 to 9), and the carrier prepared by coating the ferrite particle with a resin exhibits a resistance of 1.0.times.10.sup.9 to 1.0.times.10.sup.15 .OMEGA. when a voltage 250 V is applied thereto, and has a true specific gravity of 4.70 or below.

Ferrite carrier for electrophotographic developer and developer using

A ferrite carrier for electrophotographic developers which comprises a lithium-based ferrite having the general formula

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Kashiwa, Japan

Kouichi Shimizu