According to the present invention, there is provided a carrier core material that is formed of ferrite particles in which 48 to 52 mass % of Fe, 16 to 22 mass % of Mn, 1.0 to 3.5 mass % of Mg and 0.05 to 0.5 mass % of Ca are included, and when an electrical resistance value with an applied voltage of 500 V in an environment (in an L/L environment) in which the temperature is 10° C. and the relative humidity is 35% is R.sub.L (Ω.Math.cm), and an electrical resistance value with an applied voltage of 500 V in an environment (in an H/H environment) in which the temperature is 30° C. and the relative humidity is 70% is R.sub.H (Ω.Math.cm), formula (1) below is satisfied.
0.1≤(log R.sub.L−log R.sub.H)≤0.3  (1)

Provided is an electrophotographic developer set having a toner and a powder adhesive, wherein the toner comprises a thermoplastic resin A; the powder adhesive comprises a thermoplastic resin B and a wax A; the wax A has two or more ester groups in the molecule; the thermoplastic resin B has an ester group; and in a viscoelasticity measurement, with Gt′(100) (Pa) being a storage elastic modulus at 100° C. of the toner, and Gb′(100) (Pa) being a storage elastic modulus at 100° C. of the powder adhesive, Gb′(100) is 1.00×10.sup.5 Pa or less, and Gt′(100)/Gb′(100) is 1.20 or more, as well as a method for producing a bonded product using the above electrophotographic developer set.

Provided is an electrophotographic developer set having a toner and a powder adhesive, wherein the toner comprises a thermoplastic resin A; the powder adhesive comprises a thermoplastic resin B and a wax A; the wax A has two or more ester groups in the molecule; the thermoplastic resin B has an ester group; and in a viscoelasticity measurement, with Gt′(100) (Pa) being a storage elastic modulus at 100° C. of the toner, and Gb′(100) (Pa) being a storage elastic modulus at 100° C. of the powder adhesive, Gb′(100) is 1.00×10.sup.5 Pa or less, and Gt′(100)/Gb′(100) is 1.20 or more, as well as a method for producing a bonded product using the above electrophotographic developer set.

An object of the present invention is to provide a ferrite particle having a low apparent density, filling a specified volume with a low weight with various properties maintained in a controllable state, a ferrite carrier core material composed of the ferrite particle, and a ferrite carrier using the ferrite core material and an electrophotographic developer. To achieve the object, the ferrite particle having the outer shell structure containing the Ti oxide for the ferrite carrier core material, and the ferrite carrier using the ferrite particle as the ferrite carrier core material and the electrophotographic developer are employed.

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.

An object of the present invention is to provide an electrostatic charge image developing toner, a two-component developer, and an image forming method, each capable of employing a two-component trickle touchdown developing system which ensures excellent image density stability and no occurrence of ghost and is used in an electrophotographic copier or an electrostatic recording device. The present invention provides an electrostatic charge image developing toner having positive chargeability; containing a styrene acrylic resin as the binding resin; and containing a nigrosine-containing positive charge control agent and a negative charge control agent as the charge control agent, in which the percentage content of the percentage content of the negative charge control agent in all charge control agents is not less than the percentage content of the positive charge control agent.

An electrostatic charge image developing carrier includes: magnetic particles; and a resin layer coating the magnetic particles and containing inorganic particles, in which an exposed area ratio of the magnetic particles is 0.1% or more and 4.0% or less, an average particle diameter of the inorganic particles is 5 nm or more and 90 nm or less, and a ratio B/A of a surface area B of the electrostatic charge image developing carrier to a plan view area A of the electrostatic charge image developing carrier is 1.020 or more and 1.100 or less when a surface of the electrostatic charge image developing carrier is three-dimensionally analyzed.

In a carrier core material according to the present invention, the volume moment mean D [4, 3] of O. Bluntness measured with an injection type image analysis particle size distribution meter is equal to or greater than 65% and equal to or less than 80%, and the volume moment mean D [4, 3] of ISO Roundness is equal to or greater than 80% and equal to or less than 86%. In this way, it is possible to suppress development memory and carrier adherence.

A carrier for developing an electrostatic image includes a magnetic particle and a resin layer with which the magnetic particle is coated and which contains silica particles having an average particle diameter of 50 nm or more and 200 nm or less. In the carrier, a silicon element ratio Si1 in a region in which a distance from a surface of the resin layer in a direction toward an inside is 0.1 μm or more and 0.2 μm or less and a silicon element ratio Si2 in a region in which a distance from a surface of the magnetic particle in a direction toward the surface of the resin layer is 0.0 μm or more and 0.1 μm or less satisfy formula 1-1 and formula 2-1 below.

0.005≤Si1≤2  Formula 1-1

1≤Si1/Si2≤1000  Formula 2-1

Provided is a two-component developer for electrostatic charge image development including: toner particles containing toner base particles and an external additive disposed on a surface of the toner base particles; and carrier particles having a core material particle and a shell portion disposed on a surface of the core material particle, wherein the external additive contains inorganic particles surface-modified with a surface modifier represented by the following Formula (1); and a value of an iron element content (atomic %) measured by X-ray photoelectron spectroscopy (XPS) on a surface of the carrier particles satisfies the following Expression (1),

(R.sub.1).sub.4-n—Si—(X).sub.n  Formula (1):

4.0≤{A.sub.Fe/(A.sub.c+A.sub.o+A.sub.Fe)}×100≤15.0  Expression (1):