A toner comprising a toner particle that contains a toner base particle and an organosilicon polymer on a surface of the toner base particle, wherein the organosilicon polymer forms protruded portions with a prescribed structure on the surface of the toner base particle, and in the toner cross section, when the protrusion width w is the length of the segment where a protruded portion and the toner base particle form a continuous interface, the protrusion diameter D is the maximum length of a protruded portion, and the protrusion height H is the length from the peak of the protruded portion to the line along the circumference of the toner base particle surface, the numerical proportion of these protruded portions having a ratio D/w of the protrusion diameter D to the protrusion width w from 0.33 to 0.80, is a least 70 number %.

It is a two-component developer for electrostatic charge image development, which contains toner containing at least a binder resin and an external additive on a surface and a carrier containing a resin layer at least on a surface of a core material. The binder resin contains a crystalline polyester resin, the external additive contains alumina particles, and the resin layer contains a silicone resin.

A carrier for forming an electrophotographic image is provided. The carrier includes a core particle comprising a manganese-based ferrite particle having an apparent density of from 2.0 to 2.2 g/cm.sup.3 and a magnetization of from 44 to 52 emu/g in a magnetic field of 500 Oe; and a coating layer coating a surface of the core particle. The coating layer contains a carbon black, an inorganic particle A, and an inorganic particle B. The inorganic particle A and the carbon black each have a concentration gradient in a thickness direction of the coating layer. A concentration of the inorganic particle A increases toward a surface of the coating layer, and a concentration of the carbon black decreases toward the surface of the coating layer.

A carrier includes carrier particles. The carrier particles include first carrier particles and second carrier particles. The first carrier particles each include a first carrier core and a first coat layer covering a surface of the first carrier core. The second carrier particles each include a second carrier core and a second coat layer covering a surface of the second carrier core. The first coat layers contain no fatty acid metal salt. The second coat layer contains a coat layer binder resin and a fatty acid metal salt. The second coat layers contain the fatty acid metal salt in a proportion of from 85 mass % to 95 mass % relative to a total mass of the second coat layers. The second carrier particles are contained in a proportion of from 7 mass % to 15 mass % relative to a total mass of the first carrier particles and the second carrier particles.

A carrier for forming an electrophotographic image is provided. The carrier comprises carrier particles each comprising a core particle and a coating layer. The coating layer comprises a coating resin and inorganic particles comprising chargeable particles A and conductive particles B. The amount of the inorganic particles is from 195 to 350 parts by mass with respect to 100 parts by mass of the coating resin. The carrier particles consist of small carrier particles (D125 m), medium carrier particles (25 m<D238 m), and large carrier particles (38 m<D3). A constituent element variation, that is a ratio of an amount of a constituent element of the inorganic particles contained in the coating layer of the small carrier particles to an amount of the same constituent element of the inorganic particles contained in the coating layer of the medium carrier, is from 10.0% to 10.0%.

An electrostatic charge image developer contains a carrier including a core and, on the core, a silicone resin-containing layer serving as a lower layer, and an acrylic resin-containing layer serving as an upper layer, or a carrier including a silicone resin-containing core and an acrylic resin-containing layer on the silicone resin-containing core; strontium titanate particles having an average primary particle size of 20 nm or more and 100 nm or less; and a toner. The percentage of a silicone resin exposed on a surface of the carrier is 0.5 area % or more and 20 area % or less.

A magnetic carrier includes a magnetic carrier particle including a magnetic carrier core particle having an amino group on a surface thereof and a resin covering layer disposed on the surface of the magnetic carrier core particle, in which the resin covering layer contains a vinyl-based copolymer and a trialkoxyalkylsilane.

The present invention provides: a ferrite carrier core material for an electrophotographic developer, the material having a mesh passing amount of 3 wt % or less as indicated by the ratio of the weight of particles passing through a 16 m-mesh to the weight of whole particles constituting a powder, and having a particle strength index of 2 wt % or less as indicated by a difference between the mesh passing amounts before and after crushing; a ferrite carrier which is for an electrophotographic developer and in which the surface of the ferrite carrier core material is coated with a resin; and an electrophotographic developer which includes the ferrite carrier and a toner.

A toner comprises a toner particle and an external additive, the toner satisfies a certain relationship with regard to l (C/m.sup.2) and s (C/m.sup.2). The toner is divided into two groups i.e. a first group and a second group with inertial classifier, the first group including a larger size of the toner particles, and the second group including a smaller size of the toner particles, and the number of the toner particles in the first group being substantially equal to the number of the toner particles in the second group. Then, al (C/m.sup.2) represents an absolute value of average surface charge density of the toner included in the first group, and s (C/m.sup.2) represents an absolute value of average surface charge density of the toner included in the second group.

An object of the present invention is to provide a ferrite carrier core material for an electrophotographic developer having desired resistance properties and charging properties with small environmental variation of resistivity and charge amount while maintaining the advantages of ferrite carriers, a ferrite carrier for an electrophotographic developer, an electrophotographic developer using the ferrite carrier, and a method for manufacturing the ferrite carrier core material for an electrophotographic developer. In order to solve the problem, a ferrite carrier core material comprising ferrite particles containing 15 mass % or more and 25 mass % or less of Mn, 0.5 mass % or more and 5.0 mass % or less of Mg, 0.05 mass % or more and 4.0 mass % of Sr, and 45 mass % or more and 55 mass % or less of Fe, with Zr localized in the surface thereof is used.