US 2017/0160664 A1 · MAGNETIC CARRIER FOR ELECTROPHOTOGRAPHIC DEVELOPER AND PROCESS FOR PRODUCING THE SAME, AND TWO-COMPONENT SYSTEM DEVELOPER

Abstract

The present invention relates to a magnetic carrier for an electrophotographic developer comprising spherical magnetic composite particles comprising a phenol resin as a binder and ferromagnetic iron oxide particles bonded to each other through the phenol resin, wherein the spherical magnetic composite particles have a ten-point mean roughness Rz of 0.3 to 2.0 μm. The magnetic carrier for an electrophotographic developer according to the present invention exhibits an excellent durability against peeling-off and abrasion of coating resins formed thereon and a high stability to mechanical stress exerted onto the carrier, is free from occurrence of spent toner, can be stably held over a long period of time without occurrence of fogging and unevenness in density of toner images, and can keep high-quality images with an excellent gradation for a long period of time.

Claims13

Dependent claims

A magnetic carrier for an electrophotographic developer comprising spherical magnetic composite particles comprising a phenol resin as a binder and ferromagnetic iron oxide particles bonded to each other through the phenol resin, wherein the spherical magnetic composite particles have a ten-point mean roughness Rz of 0.3 to 2.0 μm, wherein

the spherical magnetic composite particles further comprise dielectric particles having a relative dielectric constant of not less than 50,
a total content of the dielectric particles and the ferromagnetic iron oxide particles in the spherical magnetic composite particles is 80 to 99% by weight, and
a content of the dielectric particles in the spherical magnetic composite particles is 1 to 50% by weight based on a total amount of the ferromagnetic iron oxide particles and the dielectric particles.

Dependencies are inferred from the claim text.

Facts

Application

15/434,300Filed 16 Feb 2017

Priority

JP 2009-1354174 Jun 2009

Published

8 Jun 2017

Term ends

Not estimatedThe source records don’t support an estimate.

Classification13 codes

G03G 9/1075
Having magnetic components: structural characteristics of the carrier particles, e.g. shape or crystallographic structure
G03G 9/0819
With toner particles: characterised by the dimensions of the particles
G03G 9/0827
With toner particles: characterised by their shape, e.g. degree of sphericity
G03G 9/08755
Comprising macromolecular compounds obtained otherwise than by reactions only involving carbon-to-carbon unsaturated bonds: polyesters

Magnetic carrier for electrophotographic developer and process for producing the same, and two-component system developer

Life of this patent

Magnetic carrier for electrophotographic developer and process for producing the same, and two-component system developer

Life of this patent

Abstract

Claims13