Toda Kogyo Corporation

Canon Kabushiki Kaisha

Masaaki Fukugauchi

Kazuyuki Hayashi

Nanao Horiishi

Koso Aoki

Tomoyuki Imai

Toshiyuki Hakata

Hiroomi Kakihara

Yushi Mikuriya

Kazumi Yoshizaki

Kenji Okada

A magnetic carrier exhibiting excellent durability against mechanical impact as exerted by vibration and capable of exhibiting a stable charging performance in electrophotography is provided. The magnetic carrier is formed through a process including steps of: surface treating inorganic compound particles with a lipophilizing agent having a functional group (A) selected from epoxy group, amino group, mercapto group, organic acid group, ester group, ketone group, halogenated alkyl group and aldehyde group; forming composite particles from the surface-treated inorganic compound particles and a binder resin; and then surface-coating the composite particles with a coupling agent having a functional group (B) different from the functional group (A) of the lipophilizing agent and selected from epoxy group, amino group and mercapto group, or with a coating resin having a functional group (C) different from the functional group (A) of the lipophilizing agent and selected from epoxy group, amino group, organic acid group, ester group, ketone group and halogenated alkyl group.

Magnetic carrier

The disclosure describes a magnetic carrier for electrophotography having a number-average particle diameter of 1 to 1000 .mu.m, and comprising ferromagnetic iron compound particles, non-magnetic metal oxide particles and a phenol-based resin as a binder resin, the total amount of said ferromagnetic iron compound particles and said non-magnetic metal oxide particles being 80 to 99 wt %, and the ratio of the number-average particle diameter of said non-magnetic metal oxide particles and the number-average particle diameter of said ferromagnetic iron compound particles being more than 1.0.

Magnetic carrier for electrophotography

Disclosed herein is superparamagnetic fine particles of iron oxide having an unsaturated fatty acid adsorbed on the surface of superparamagnetic fine particles and having a magnetization of not less than 50 emu/g, the rate of change of the magnetization of not more than 10%, and an Fe.sup.2+ content (calculated as Fe.sup.2+ /Fe.sup.3+ molar ratio) of 0.16-0.5.

Superparamagnetic fine particles of iron oxide and magnetic recording

Disclosed herein is superparamagnetic fine particles of iron oxide having an unsaturated fatty acid adsorbed on the surface of superparamagnetic fine particles, and having a magnetization of not less than 50 emu/g, the rate of change of the magnetization of not more than 10%, and an Fe.sup.2+ content (calculated as Fe.sup.2+ /Fe.sup.3+ molar ratio) of 0.16-0.5.

Growing community of inventors

Hiroshima, Japan

Masaaki Fukugauchi