Patent ID: 9606467
Date: 2017-03-28
CPC Classifications: G03G

Claim:
1. 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, and further comprising on the spherical magnet particles a coating layer comprising at least one resin selected from the group consisting of a melamine resin, a silicone-based resin, a fluororesin, an acrylic resin and a styrene-acrylic resin, wherein the spherical magnetic composite particles before coating with the coating layer have a ten-point mean roughness Rz of 0.3 to 2.0 μm, a total content of the ferromagnetic iron oxide particles in the spherical magnetic composite particles is 80 to 99% by weight, the ferromagnetic iron oxide particles are constituted from ferromagnetic iron oxide particles (a) and ferromagnetic iron oxide particles (b) which are different in average particle diameter from each other, a ratio of an average particle diameter (ra) of the ferromagnetic iron oxide particles (a) having a larger average particle diameter to an average particle diameter (rb) of the ferromagnetic iron oxide particles (b) having a smaller average particle diameter (ra/rb) is more than 1, a content of the ferromagnetic iron oxide particles (a) is 1 to 50% by weight based on a total amount of the ferromagnetic iron oxide particles (a) and the ferromagnetic iron oxide particles (b), and the ferromagnetic iron oxide particles (a) and the ferromagnetic iron oxide particles (b) respectively have any shape selected from the group consisting of a spherical shape, a hexahedral shape, an octahedral shape, a polyhedral shape and an amorphous shape.