An electrophotographic image forming carrier includes core particles and a coating layer coating a surface of the core particles. The coating layer contains antimony-containing particles comprising inorganic fine particles A and antimony-doped tin oxide disposed on a surface of the inorganic fine particles A. The electrophotographic image forming carrier has an apparent density of 2.0 g/cm.sup.3 or more and 2.5 g/cm.sup.3 or less.

An electrostatic charge image developing carrier contains a magnetic particle and a resin coating layer coating the magnetic particle, in which the resin coating layer contains inorganic particles, a ratio B/A of a surface area B of the carrier to a plan view area A of the carrier that are obtained by three-dimensional analysis of a surface of the carrier is 1.020 or more and 1.100 or less, a volume average particle diameter of the magnetic particle is 25 ?m or more and 34 ?m or less, and a fluidity of the magnetic particle is 28 s/50 g or more and 36 s/50 g or less.

A two-component developer includes toner particles and carrier particles. The toner particles each include a toner mother particle and first resin particles. The carrier particles each include a carrier mother particle and second resin particles. An amount of the second resin particles is at least 0.010 parts by mass and no greater than 0.100 parts by mass relative to 100 parts by mass of the carrier mother particles. The first resin particles and the second resin particles have a number average primary particle diameter of at least 40 nm and no greater than 100 nm and a blocking rate (measurement temperature: 160 C.) of less than 30% by mass. A difference in blocking rate between the first resin particles and the second resin particles is no greater than 5% by mass, and a difference in number average primary particle diameter therebetween is no greater than 5 nm.

To provide a magnetic core material for electrophotographic developer and carrier for electrophotographic developer which are excellent in a rising-up of charge amount, can suppress a carrier scattering, and can stably provide good images; a developer containing the carrier; a method for producing the magnetic core material for electrophotographic developer; a method for producing the carrier for electrophotographic developer; and a method for producing the developer.

The magnetic core material for electrophotographic developer, containing a sulfur component in a content of from 1 to 45 ppm in terms of a sulfate ion.

The present invention provides a two-component developer for developing an electrostatic charge image, which includes a toner and a carrier, wherein the toner contains an amorphous resin and a crystalline resin as binder resins and an inorganic particle as external additive particle, and the carrier has a surface to which silica particles having a number average particle diameter of 10 to 30 nm are attached in an amount in the range of the following Equation (1): 5 at %S110 at %, wherein S1 represents a concentration of Si element as measured by XPS and indicates an amount of silica on the surface of the carrier.

Provided are a ferrite carrier core material for an electrophotographic developer having a full length L.sub.1 of grain boundary and a circumference length L.sub.2 of the core material in a cross-section of the core material, and satisfying a relationship of 2L.sub.1/L.sub.29; a carrier for an electrophotographic developer including the ferrite carrier core material and a coating layer containing a resin provided on a surface of the ferrite carrier core material; and an electrophotographic developer including the carrier and a toner.

An electrostatic charge image developing carrier, containing: a magnetic particle; and a resin coating layer that coats the magnetic particle and contains inorganic particles, and the electrostatic charge image developing carrier has a surface roughness satisfying a ratio B/A of a surface area B to a plan view area A of 1.020 or more and 1.100 or less, the plan view area A and the surface area B being obtained by three-dimensional analysis of the surface, and the magnetic particle has a surface roughness satisfying 0.5 ?m?Sm?2.5 ?m and 0.3 ?m?Ra?1.2 ?m, and Sm represents an average ruggedness interval and Ra represents an arithmetic average surface roughness.

In a two-component developer, toner particles include toner mother particles and external additive particles including strontium titanate particles. A first percentage content being a percentage content of the strontium titanate particles to the mass of the toner mother particles is 0.30-0.90% by mass. The carrier particles include carrier cores and coat layers. The coat layers contain barium titanate particles and a coating resin including a silicone resin. The barium titanate particles have a number average primary particle diameter of 100-500 nm. A second percentage content being a percentage content of the coat layers to the mass of the carrier cores is 2.0-4.0% by mass. A third percentage content being a percentage content of the barium titanate to the mass of the coating resin satisfies formula (1) (X?10)?Z?45.0. In formula (1), X represents the first percentage content and Z represents the third percentage content.

Provided is a two-component developer for developing an electrostatic latent image incorporating: toner particles each containing a toner mother particle having an external additive on a surface of the toner mother particle; and carrier particles each having a core material particle and a covering layer containing a resin on a surface of the core material particle, wherein the external additive contains inorganic particles; the inorganic particles are subjected to surface modification with silicone oil; a carbon content remained on a surface of the inorganic particle after the surface modification is within 3.0 to 10.0 mass %; a free carbon ratio on the surface of the inorganic particle is 70.0% or more; the carrier particles have a resistance in the range of 1.010.sup.9 to 5.010.sup.10 .Math.cm; and the resin in the covering layer contains a resin formed from a monomer containing an alicyclic methacrylic acid ester monomer.

An object of the present invention is to provide ferrite particles for supporting a catalyst having a small apparent density, various properties are maintained in a controllable state and a specified volume is filled with a small weight, and a catalyst using the ferrite particles for supporting a catalyst. To achieve the object, ferrite particles for supporting a catalyst provided with an outer shell structure containing Ti oxide, a catalyst using the ferrite particles for supporting a catalyst are employed.