The present invention provides a magnetic carrier for an electrophotographic developer which has an excellent durability and a stable charging property and is free from occurrence of spent toner thereonto, and a two-component system developer comprising the magnetic carrier for an electrophotographic developer and a toner. The present invention relates to a core material of a magnetic carrier for an electrophotographic developer comprising spherical composite particles comprising at least ferromagnetic iron oxide fine particles and a cured phenol resin and having an average particle diameter of 1 to 100 μm, a resin index of the spherical composite particles being within the range of 35 to 80%, and a magnetic carrier obtained by coating a surface of respective particles of the magnetic carrier core material with a resin.

According to one embodiment, a colorable material capable of achieving a high image density during coloration is provided. A colorable material according to an embodiment contains: colorable particles including porous particles as a color developing agent composed of an inorganic oxide and a color developable agent carried on the porous particles; and a thermoplastic resin coating the colorable particles.

A carrier for two-component developer includes a magnetic particle and a resin coating layer that covers the magnetic particle and contains a resin, wherein a weight average molecular weight of the resin contained in the resin coating layer is from 1,800,000 to 5,000,000.

A developer includes a toner including toner particles and a carrier including carrier particles. The carrier particles each include a carrier core and a carrier coating layer covering the carrier core. The carrier coating layer contains a fluorine-containing resin. The toner particles each include a toner mother particle and resin particles located on a surface of the toner mother particle. The resin particles have a number average primary particle diameter of at least 70 nm and no greater than 200 nm. A dispersion obtained by dispersing 0.1 g of the resin particles in 100 mL of distilled water has an electrical conductivity of at least 2.5 μS/m and no greater than 6.0 μS/m. A degree of aggregation Y.sub.160 of the resin particles represented by expression (1) “Y.sub.160=100×M.sub.160A/M.sub.160B” is at least 15% by mass and no greater than 40% by mass.

A magnetic carrier including a magnetic core and a coating resin configured to coat the surface of the magnetic core. The coating resin contains a graft resin A and a graft resin B. The coating resin (i) contains 1.0 mass % or more and 50.0 mass % or less of the graft resin A, and (ii) contains 50.0 mass % or more and 99.0 mass % or less of the graft resin B. The graft resin A has a unit Y1 represented by formula (1) and a unit Y2 represented by formula (2). The graft resin B (i) is a comb-shaped polymer having, as a branch, at least one moiety selected from, for example, a styrene-based polymer moiety and a (meth)acrylate-based polymer moiety, and (ii) contains the polysiloxane structure moiety at a content of 0.1 mass % or less.

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The present invention relates to a carrier including: a magnetic core material; and a resin coating layer coating a surface of the magnetic core material, in which the resin coating layer contains a binder resin, and fluorine element-containing resin particles dispersed in the binder resin, the resin coating layer has a coefficient of variation of a film thickness of 25% or less, and the resin coating layer has an average value of the number of the fluorine element-containing resin particles being 3 particles/μm.sup.2 or more and 350 particles/μm.sup.2 or less per unit area in a cross section of the resin coating layer, and has a coefficient of variation thereof being 20% or less.

A carrier for electrostatic image development includes: a core material; and a resin coating layer that contains nitrogen-containing silica particles and nitrogen-containing resin fine particles and covers the core material. The content of the nitrogen-containing silica particles is from 10% by mass to 55% by mass inclusive based on the total mass of the resin coating layer. The nitrogen-containing resin fine particles have a volume average particle diameter of from 100 nm to 250 nm inclusive. The mass ratio P/S of the mass P of the nitrogen-containing resin fine particles to the mass S of the nitrogen-containing silica particles is from 0.15 to 0.55 inclusive.

An electrostatic charge image developer contains toner particles, silica particles that are added to an exterior of the toner particles and contain a nitrogen element-containing compound, and a carrier that has a core material and a nitrogen element-containing coating resin layer, in which a content of the nitrogen element-containing compound with respect to the silica particles is 0.005% by mass or more and 0.5% by mass or less in terms of a nitrogen element, and in a case where A represents a pore volume of pores that the silica particles include and have a diameter of 1 nm or more and 50 nm or less, which is determined from a pore size distribution curve obtained by a nitrogen adsorption method before baking of the silica particles at 350° C., and B represents a pore volume of pores that the silica particles include and have a diameter of 1 nm or more and 50 nm or less, which is determined from a pore size distribution curve obtained by a nitrogen adsorption method after baking of the silica particles at 350° C., B/A is 1.2 or more and 5 or less and B is 0.2 cm.sup.3/g or more and 3 cm.sup.3/g or less.

A method for producing a carrier for developing an electrostatic charge image, the method includes: adding a coating liquid containing a resin, conductive particles, and a solvent and magnetic particles to a mixer having a stirring blade, and mixing the coating liquid and the magnetic particles to obtain a mixture; and evaporating and drying the solvent from the mixture to produce a carrier having a resin coating layer on surfaces of the magnetic particles, wherein a viscosity μ of the coating liquid when being added to the mixer is more than 60 mPa.Math.s and 1,000 mPa.Math.s or less, and a value of a ratio μ/W of the viscosity μ(mPa.Math.s) to an amount W (parts by mass) of the resin coating layer with respect to 100 parts by mass of the magnetic particles in the carrier is 20 or more and 500 or less.

There is provided a carrier including a magnetic core material having a surface coated with a surfactant-containing resin mixture of an elemental fluorine-containing resin and a polyimide resin. The carrier has an elution amount of an eluted material into water in an elution test ranging from 180 ppm to 3,500 ppm.