Mitsui Minings & Melting Co., Ltd.

Powdertech Co., Ltd.

Takashi Nakashima

Hiromichi Kobayashi

Yuji Sato

Yoichi Kamikoriyama

Kenji Suzuoka

Kazuya Kinoshita

Takeshi Gondo

Takashi Hikichi

Shoichi Fujiyasu

Koichi Katsuyama

Tomoyuki Hoshino

A carrier for electrophotographic developer comprises a resin carrier core comprising a binder resin and magnetic powder dispersed in the binder resin, and a coating layer comprising a coating resin on a surface of the core, the binder resin being a silicone resin obtained by curing of a polysiloxane compound (A) having an epoxy group and a polysiloxane compound (B) having a group capable of reacting with the epoxy group, due to a ring-opening addition reaction; the binder resin containing a functional group which is an epoxy group and/or a group capable of reacting with an epoxy group; the coating resin containing a functional group capable of reacting with the functional group of the binder resin; the functional group of the coating resin and the function group of the binder resin forming a chemical bond.

Carrier for electrophotographic developer and two-component electrophotographic developer

Disclosed is a black pigment having adequate degree of blackness and high electrical resistance at the same time. Specifically disclosed is a granular black pigment containing cobalt which is characterized in that it is composed of an oxide containing at least cobalt and the divalent cobalt content accounts for 40-70% of the total cobalt content. It is preferable that the total cobalt content in a whole particle is 60-80% by mass, and the divalent cobalt content in a whole particle is 20-50% by mass. It is also preferable that the primary particle diameter is 0.02-0.6 &#x3bc;m.

Cobalt-containing black pigment particulates

Provided are a carrier for electrophotography developers prepared by generating a slight amount of byproducts such as water, alcohol, etc, which carrier is free from release of a magnetic powder, has excellent mechanical strength and durability, and good environmental stability, and further can restrain occurrence of toner spent condition and has favorable fluidity and excellent capability of imparting charging to a toner, a two-component developer comprising the carrier and a method for forming an image using the developer. The carrier for electrophotography developers comprises a magnetic powder dispersed binder resin, the binder resin material comprises (A) a polysiloxane compound having an epoxy group as a functional group and (B) a polysiloxane compound having a group capable of ring-opening addition reaction with the epoxy group of the polysiloxane compound (A), and the binder resin is a silicone resin prepared by curing with ring-opening addition reaction of the epoxy resin. The developer comprises the carrier for electrophotography developers and the toner particle. The method for forming an image comprises developing a static latent image by the developer with an alternating electric field.

Carrier for electrophotography developers, developer prepared by using the carrier and method for forming image

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Ageo, Japan

Takashi Nakashima