Abstract: A carrier core material includes ferrite particles, contains CaSiO3, and has a true density at least equal to 3.5 g/cm3 and at most equal to 4.5 g/cm3. A particle strength index calculated from formula (1) is preferably at most equal to 1.5% by volume. (1): Particle strength index=V2?V1 (In the formula, V1: cumulative value (% by volume) of particle size 22 ?m or less in cumulative particle size distribution of carrier core material before crushing test, and V2: cumulative value (% by volume) of particle size 22 ?m or less in cumulative particle size distribution of carrier core material after crushing test) Crushing test conditions: 30 g of carrier core material crushed using a sample mill for 60 seconds at a rotational speed of 14000 rpm.

Abstract: 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 RL (?·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 RH (?·cm), formula (1) below is satisfied. 0.1?(log RL?log RH)?0.

Abstract: 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.

Abstract: 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 RL (?·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 RH (?·cm), formula (1) below is satisfied. 0.1?(log RL?log RH)?0.

Abstract: A carrier core material is represented by a composition formula MXFe3-XO4 (where M is at least one type of metal element selected from Mg, Mn, Ca, Ti, Cu, Zn and Ni, 0<X<1), in which part of M and/or Fe is substituted with Sr and formed of ferrite particles, and in the carrier core material, a Sr content is equal to or more than 2500 ppm but equal to or less than 12000 ppm, the amount of Sr eluted with pure water at a temperature of 25° C. is equal to or less than 50 ppm, an apparent density is equal to or more than 1.85 g/cm3 but equal to or less than 2.25 g/cm3 and magnetization ?1k when a magnetic field of 79.58×103 A/m (1000 oersteds) is applied is equal to or more than 63 Am2/kg but equal to or less than 75 Am2/kg.

Abstract: In a projection material for mechanical plating, a steel particle is used as a core, and the surrounding surface thereof is coated with a zinc alloy in which the content of Al is more than 5% by mass but equal to or less than 16% by mass, the content of Mg is equal to or more than 5.5% by mass but equal to or less than 15% by mass and the remaining portion is Zn and an impurity, and the content of Fe is equal to or more than 3% by mass but equal to or less than 80% by mass. In this way, the corrosion resistance of a zinc-based coating itself formed in mechanical plating is remarkably enhanced without dependence on protective coating formation treatment such as chromate treatment.

Abstract: A carrier core material formed with ferrite particles, the skewness Rsk of the particle is equal to or more than ?0.40 but equal to or less than ?0.20, and the kurtosis Rku of the particle is equal to or more than 3.20 but equal to or less than 3.50. Here, the maximum height Rz of the particle is equal to or more than 2.20 ?m but equal to or less than 3.50 ?m. Moreover, the ferrite particle contains at least either of Mn and Mg elements. In this way, cracking or chipping in a concave-convex portion of a particle surface is unlikely to occur, and moreover, the amount of coating resin used can be reduced without properties such as electrical resistance being lowered.

Abstract: A carrier core material is represented by a composition formula MXFe3-XO4 (where M is at least one type of metal element selected from Mg, Mn, Ca, Ti, Cu, Zn and Ni, 0<X<1), in which part of M and/or Fe is substituted with Sr and formed of ferrite particles, and in the carrier core material, a Sr content is equal to or more than 2500 ppm but equal to or less than 12000 ppm, the amount of Sr eluted with pure water at a temperature of 25° C. is equal to or less than 50 ppm, an apparent density is equal to or more than 1.85 g/cm3 but equal to or less than 2.25 g/cm3 and magnetization ?1k when a magnetic field of 79.58×103 A/m (1000 oersteds) is applied is equal to or more than 63 Am2/kg but equal to or less than 75 Am2/kg.

Abstract: A carrier core material formed with ferrite particles, the skewness Rsk of the particle is equal to or more than ?0.40 but equal to or less than ?0.20, and the kurtosis Rku of the particle is equal to or more than 3.20 but equal to or less than 3.50. Here, the maximum height Rz of the particle is equal to or more than 2.20 ?m but equal to or less than 3.50 ?m. Moreover, the ferrite particle contains at least either of Mn and Mg elements. In this way, cracking or chipping in a concave-convex portion of a particle surface is unlikely to occur, and moreover, the amount of coating resin used can be reduced without properties such as electrical resistance being lowered.

Abstract: A carrier core material is provided that is formed with ferrite particles which can uniformly adhere a coupling agent to the entire surface. A carrier core material is formed with ferrite particles, and the powder pH of the ferrite particles is equal to or more than 9. Here, the ferrite particles are preferably formed of Mn ferrite or Mn—Mg ferrite. The ferrite particles preferably contain 45 wt % or more but 65 wt % or less of Fe, 15 wt % or more but 30 wt % or less of Mn and 5 wt % or less of Mg.

Abstract: In a projection material for mechanical plating, a steel particle is used as a core, and the surrounding surface thereof is coated with a zinc alloy in which the content of Al is more than 5% by mass but equal to or less than 16% by mass, the content of Mg is equal to or more than 5.5% by mass but equal to or less than 15% by mass and the remaining portion is Zn and an impurity, and the content of Fe is equal to or more than 3% by mass but equal to or less than 80% by mass. In this way, the corrosion resistance of a zinc-based coating itself formed in mechanical plating is remarkably enhanced without dependence on protective coating formation treatment such as chromate treatment.

Abstract: A carrier core material includes, a main component, a material represented by a composition formula MnXMYFe3?(X+Y)O4 (where M is selected from Mg, Ti, Cu, Zn and Ni, 0<X, 0?Y, 0<X+Y<1), in which 0.1 to 1.0 mol % of at least one of Sr element and Ca element is contained as the total amount by conversion to SrO or CaO and in which the frequency of a grain whose length RSm is equal or more than 8.0 ?m among grains appearing on the surface of particles of the carrier core material is equal to or less than 2.0 number percent. In this way, the degradation of a carrier caused by long-term use such as the separation of a coating resin is significantly reduced, stable charging performance is maintained and the cracking or chipping of the particles is reduced.

Abstract: A carrier core material is represented by a composition formula MxFe3-xO4 (where M is Mn and/or Mg, and X is a total of Mn and Mg and is a substitution number of Fe by Mn and Mg, 0<X?1), in which 5 to 20 number percent of bound particles where 2 to 5 spherical particles are bound together are contained and in which the maximum peak-to-trough depth Rz of the surface of normal spherical particles other than the bound particles is equal to or more than 1.5 ?m but equal to or less than 2.1 ?m. In this way, it is possible to increase the amount of toner supplied to a development region, and the surface of a photosensitive member is prevented from being scratched by a magnetic brush.

Abstract: A carrier core material is represented by a composition formula MxFe3-xO4 (where M is Mn and/or Mg, and X is a total of Mn and Mg and is a substitution number of Fe by Mn and Mg, 0<X?1), in which 5 to 20 number percent of bound particles in which 2 to 5 spherical particles are bound together are contained, and in which the absolute value of a difference between lattice constants before and after milling which are calculated from a peak position of plane indices in a powder X-ray diffraction pattern is equal to or less than 0.005. In this way, it is possible to increase the amount of toner supplied to a development region, and even when cracking or chipping occurs in the carrier core material, an image failure such as black spots or white spots is prevented from being generated.

Abstract: A carrier core material is represented by a composition formula MxFe3-xO4 (where M is Mn and/or Mg, and X is a total of Mn and Mg and is a substitution number of Fe by Mn and Mg, 0<X?1), in which 5 to 20 number percent of bound particles where 2 to 5 spherical particles are bound together are contained and in which the maximum peak-to-trough depth Rz of the surface of normal spherical particles other than the bound particles is equal to or more than 1.5 ?m but equal to or less than 2.1 ?m. In this way, it is possible to increase the amount of toner supplied to a development region, and the surface of a photosensitive member is prevented from being scratched by a magnetic brush.

Abstract: A carrier core material includes, a main component, a material represented by a composition formula MnXMYFe3-(X+Y)O4 (where M is selected from Mg, Ti, Cu, Zn and Ni, 0<X, 0?Y, 0<X+Y<1), in which 0.1 to 1.0 mol % of at least one of Sr element and Ca element is contained as the total amount by conversion to SrO or CaO and in which the frequency of a grain whose length RSm is equal or more than 8.0 ?m among grains appearing on the surface of particles of the carrier core material is equal to or less than 2.0 number percent. In this way, the degradation of a carrier caused by long-term use such as the separation of a coating resin is significantly reduced, stable charging performance is maintained and the cracking or chipping of the particles is reduced.

Abstract: A carrier core material is provided that is formed with ferrite particles which can uniformly adhere a coupling agent to the entire surface. A carrier core material is formed with ferrite particles, and the powder pH of the ferrite particles is equal to or more than 9. Here, the ferrite particles are preferably formed of Mn ferrite or Mn—Mg ferrite. The ferrite particles preferably contain 45 wt % or more but 65 wt % or less of Fe, 15 wt % or more but 30 wt % or less of Mn and 5 wt % or less of Mg.

Abstract: Ferrite particles have, as a main component, a material represented by a composition formula MxFe3?xO4 (where M is at least one type of metal selected from a group made of Mg, Mn, Ca, Ti, Cu, Zn, Sr and Ni, 0<x<1), where the maximum height Rz of the particles falls within a range of 1.40 ?m to 1.90 ?m, and the degree of distortion Rsk of the particles falls within a range of ?0.25 to ?0.07. In this way, when the ferrite particles are used as the carrier of an electrophotographic image forming apparatus, even if an image formation speed is increased, the occurrence of a failure is reduced for a long period of time.

Abstract: This invention is directed to a method for manufacturing carrier core particles for electrophotographic developer containing iron, manganese, and calcium as a core composition. The method includes (A) a mixing step of mixing an iron-containing raw material, a manganese-containing raw material, and a calcium-containing raw material to prepare a mixture thereof, (C) a granulation step of granulating the mixture after the mixing step, and (D) a firing step of firing a powdery material, which is obtained by granulating the mixture in the granulation step, at a predetermined temperature to form a magnetic phase. The calcium-containing raw material is provided in a granular form, and primary particles of the calcium-containing raw material have a volume mean diameter of 1 ?m or less.

Abstract: There are provided ferrite particles in which Mn ferrite is used as the main phase and which contain Sr ferrite, where the degree of projections and recesses in the surface of the particles falls within a range of 2.5 to 4.5 ?m, and the standard deviation of the size of grains appearing on the surface of the particles falls within a range of 1.5 to 3.5 ?m. In this way, a coating resin is left on the surface of the particles even after long-term use and thus a decrease in the charging property is reduced.