An electrostatic image developer includes a toner including toner particles that include a binder resin and a release agent and have an exposure ratio of the release agent of 15% or more and 30% or less, and a carrier including magnetic particles and resin cover layers covering the magnetic particles and including inorganic particles, wherein the inorganic particles have an arithmetic average particle size of 5 nm or more and 90 nm or less, the resin cover layers have an average thickness of 0.6 μm or more and 1.4 μm or less, and a fine-irregularity-structure surface roughness of surfaces of the carrier three-dimensionally analyzed has, in an analysis region, a ratio B/A of an irregularity-surface area B to a plan-view area A of 1.020 or more and 1.100 or less.

A toner for developing an electrostatic charge image contains toner particles containing at least one binder resin, a release agent, and a coloring agent, and a cross-sectional image of the toner particles meets requirements (1) and (2): requirement (1), an average of ten or more domains, per toner particle, of the release agent have an area of 0.5% or more and 5.0% or less of the area of the toner particle; requirement (2), in a Voronoi tessellation generated from the centroids of the domains of the coloring agent, the mean area of the Voronoi cells is 0.020 μm.sup.2 or more and 0.060 μm.sup.2 or less, and the standard deviation of the areas of the Voronoi cells is 0.010 μm.sup.2 or less.

A toner for developing an electrostatic charge image contains toner particles containing at least one binder resin, a release agent, and a coloring agent, and a cross-sectional image of the toner particles meets requirements (1) and (2): requirement (1), an average of ten or more domains, per toner particle, of the release agent have an area of 0.5% or more and 5.0% or less of the area of the toner particle; requirement (2), in a Voronoi tessellation generated from the centroids of the domains of the coloring agent, the mean area of the Voronoi cells is 0.020 μm.sup.2 or more and 0.060 μm.sup.2 or less, and the standard deviation of the areas of the Voronoi cells is 0.010 μm.sup.2 or less.

A toner for developing an electrostatic charge image contains toner particles containing at least one binder resin, a release agent, and a coloring agent, and a cross-sectional image of the toner particles meets requirements (1) and (2): requirement (1), an average of ten or more domains, per toner particle, of the release agent have an area of 0.5% or more and 5.0% or less of the area of the toner particle; requirement (2), in a Voronoi tessellation generated from the centroids of the domains of the coloring agent, the mean area of the Voronoi cells is 0.020 μm.sup.2 or more and 0.060 μm.sup.2 or less, and the standard deviation of the areas of the Voronoi cells is 0.010 μm.sup.2 or less.

A toner for developing an electrostatic charge image contains toner particles containing at least one binder resin, a release agent, and a coloring agent, and a cross-sectional image of the toner particles meets requirements (1) and (2): requirement (1), an average of ten or more domains, per toner particle, of the release agent have an area of 0.5% or more and 5.0% or less of the area of the toner particle; requirement (2), in a Voronoi tessellation generated from the centroids of the domains of the coloring agent, the mean area of the Voronoi cells is 0.020 μm.sup.2 or more and 0.060 μm.sup.2 or less, and the standard deviation of the areas of the Voronoi cells is 0.010 μm.sup.2 or less.

An electrostatic image developer includes a toner containing toner particles, a carrier, and an external additive containing titanium dioxide particles of two types having different refractive indexes, fatty acid metal salt particles, and an abrasive.

The present invention relates to a ferrite particle containing a crystal phase component containing a perovskite crystal represented by a compositional formula: RZrO.sub.3 (provided that R represents an alkaline earth metal element), having a surface roughness Rz of 0.8 .Math.m or more and 3.5 .Math.m or less, and having a standard deviation Rzσ of the surface roughness Rz falling in a range represented by the following formula 0.15 × Rz ≤ Rzσ ≤ 0.60 × Rz. The ferrite particle can be used as an electrophotographic developer carrier core material. In addition, an electrophotographic developer carrier and an electrophotographic developer can be obtained.

The present invention relates to a ferrite particle containing a crystal phase component containing a perovskite crystal represented by a compositional formula: RZrO.sub.3 (provided that R represents an alkaline earth metal element), having a surface roughness Rz of 2.0 μm or more and 4.5 μm or less, and satisfying the following formulas: 6.5≤log H.sub.1000≤8.5 and 0.80≤log H.sub.1000/log H.sub.100≤1.00. The ferrite particle can be used as an electrophotographic developer carrier core material. In addition, an electrophotographic developer carrier and an electrophotographic developer can be obtained.

The present invention relates to a ferrite particle containing a crystal phase component containing a perovskite crystal represented by a compositional formula: RZrO.sub.3 (provided that R represents an alkaline earth metal element), having a surface roughness Rz of 2.0 μm or more and 4.5 μm or less, and satisfying the following formulas: 6.5≤log H.sub.1000≤8.5 and 0.80≤log H.sub.1000/log H.sub.100≤1.00. The ferrite particle can be used as an electrophotographic developer carrier core material. In addition, an electrophotographic developer carrier and an electrophotographic developer can be obtained.

According to one embodiment, a toner having excellent heat roller life performance, low-temperature offset resistance, and high-temperature offset resistance, and a toner cartridge and an image forming apparatus, in each of which the toner is stored, are provided.

A toner according to an embodiment contains a colorant, an amorphous polyester resin A, and an amorphous polyester resin B. The amorphous polyester resin A has an Mw.sub.A of 0.9×10.sup.4 to 1.5×10.sup.4. The amorphous polyester resin B has an Mw.sub.B of 4.0×10.sup.4 to 11.0×10.sup.4. The amorphous polyester resin A has an Mn.sub.A of 3.0×10.sup.3 to 4.0×10.sup.3. Mw.sub.A/Mn.sub.A is between 3.1 and 4.0. The amorphous polyester resin B has an Mn.sub.B of 2.2×10.sup.3 to 3.5×10.sup.3. Mw.sub.B/Mn.sub.B is between 11.4 and 50. The content of the amorphous polyester resin A is between 50 and 60 mass %. The content of the amorphous polyester resin B is between 20 and 30 mass %.