Abstract: The present invention relates to a magnetic carrier for an electrophotographic developer comprising spherical composite core particles comprising at least ferromagnetic iron oxide fine particles and a cured phenol resin, and having an average particle diameter of 20 to 60 ?m, the magnetic carrier for an electrophotographic developer satisfying the formula (1): ?1??0=?2 to 0 wherein ?0 represents a saturation magnetization (Am2/kg) of the carrier particles having a particle diameter in the vicinity of the average particle diameter of the magnetic carrier for an electrophotographic developer; and ?1 represents a saturation magnetization (Am2/kg) of the carrier particles having a particle diameter of less than 20 ?m, and a two-component system developer using the magnetic carrier.

Abstract: The present invention relates to a magnetic carrier for an electrophotographic developer comprising spherical magnetic composite particles comprising a phenol resin as a binder and ferromagnetic iron oxide particles bonded to each other through the phenol resin, wherein the spherical magnetic composite particles have a ten-point mean roughness Rz of 0.3 to 2.0 ?m. The magnetic carrier for an electrophotographic developer according to the present invention exhibits an excellent durability against peeling-off and abrasion of coating resins formed thereon and a high stability to mechanical stress exerted onto the carrier, is free from occurrence of spent toner, can be stably held over a long period of time without occurrence of fogging and unevenness in density of toner images, and can keep high-quality images with an excellent gradation for a long period of time.

Abstract: 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 ?m, 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.

Abstract: The present invention relates to a magnetic carrier for an electrophotographic developer comprising spherical magnetic composite particles comprising a phenol resin as a binder and ferromagnetic iron oxide particles bonded to each other through the phenol resin, wherein the spherical magnetic composite particles have a ten-point mean roughness Rz of 0.3 to 2.0 ?m. The magnetic carrier for an electrophotographic developer according to the present invention exhibits an excellent durability against peeling-off and abrasion of coating resins formed thereon and a high stability to mechanical stress exerted onto the carrier, is free from occurrence of spent toner, can be stably held over a long period of time without occurrence of fogging and unevenness in density of toner images, and can keep high-quality images with an excellent gradation for a long period of time.

Abstract: The present invention relates to a magnetic carrier for an electrophotographic developer comprising spherical magnetic composite particles comprising a phenol resin as a binder and ferromagnetic iron oxide particles bonded to each other through the phenol resin, wherein the spherical magnetic composite particles have a ten-point mean roughness Rz of 0.3 to 2.0 ?m. The magnetic carrier for an electrophotographic developer according to the present invention exhibits an excellent durability against peeling-off and abrasion of coating resins formed thereon and a high stability to mechanical stress exerted onto the carrier, is free from occurrence of spent toner, can be stably held over a long period of time without occurrence of fogging and unevenness in density of toner images, and can keep high-quality images with an excellent gradation for a long period of time.

Abstract: Black magnetic iron oxide particles having an average particle diameter of 0.05 to 2.0 ?m and an electric resistance value at an applied voltage of 100 V of not less than 1×108 ?·cm. Also a magnetic carrier for electrophotographic developer having spherical magnetic composite particles obtained by dispersing black magnetic iron oxide particles in a binder resin. The magnetic carrier has an electric resistance value R100 at an applied voltage of 100 V of 1×108 to 1×1014 ?·cm, and an electric resistance value R300 at an applied voltage of 300 V which satisfies the relationship represented by the formula: 0.1?R300/R100?1.

Abstract: The present invention relates to a magnetic carrier for an electrophotographic developer comprising spherical composite core particles comprising at least ferromagnetic iron oxide fine particles and a cured phenol resin, and having an average particle diameter of 20 to 60 ?m, the magnetic carrier for an electrophotographic developer satisfying the formula (1): ?1??0=?2 to 0 wherein ?0 represents a saturation magnetization (Am2/kg) of the carrier particles having a particle diameter in the vicinity of the average particle diameter of the magnetic carrier for an electrophotographic developer; and ?1 represents a saturation magnetization (Am2/kg) of the carrier particles having a particle diameter of less than 20 ?m, and a two-component system developer using the magnetic carrier.

Abstract: The present invention relates to a magnetic carrier for an electrophotographic developer comprising spherical composite particles comprising spherical composite core particles comprising at least ferromagnetic iron oxide fine particles and a cured phenol resin and having an average particle diameter of 1 to 100 ?m, and a melamine resin coating layer formed on the respective core particles, wherein a ratio of R100 to R300 (R100/R300) in which R100 is an electric resistance value as measured when applying a voltage of 100 V to the magnetic carrier; and R300 is an electric resistance value as measured when applying a voltage of 300 V to the magnetic carrier, is controlled to lie within the range of 1 to 50.

Abstract: 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 ?m, 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.

Abstract: The present invention relates to a magnetic carrier for an electrophotographic developer comprising spherical magnetic composite particles comprising a phenol resin as a binder and ferromagnetic iron oxide particles bonded to each other through the phenol resin, wherein the spherical magnetic composite particles have a ten-point mean roughness Rz of 0.3 to 2.0 ?m. The magnetic carrier for an electrophotographic developer according to the present invention exhibits an excellent durability against peeling-off and abrasion of coating resins formed thereon and a high stability to mechanical stress exerted onto the carrier, is free from occurrence of spent toner, can be stably held over a long period of time without occurrence of fogging and unevenness in density of toner images, and can keep high-quality images with an excellent gradation for a long period of time.

Abstract: The present invention relates to a magnetic carrier for an electrophotographic developer comprising spherical composite particles comprising spherical composite core particles comprising at least ferromagnetic iron oxide fine particles and a cured phenol resin and having an average particle diameter of 1 to 100 ?m, and a melamine resin coating layer formed on the respective core particles, wherein a ratio of R100 to R300 (R100/R300) in which R100 is an electric resistance value as measured when applying a voltage of 100 V to the magnetic carrier; and R300 is an electric resistance value as measured when applying a voltage of 300 V to the magnetic carrier, is controlled to lie within the range of 1 to 50.

Abstract: The present invention relates to black magnetic iron oxide particles having an average particle diameter of 0.05 to 2.0 ?m and an electric resistance value at an applied voltage of 100 V of not less than 1×108 ?·m; and a magnetic carrier for electrophotographic developer comprising spherical magnetic composite particles obtained by dispersing black magnetic iron oxide particles in a binder resin, wherein the magnetic carrier has an electric resistance value R100 at an applied voltage of 100 V of 1×108 to 1×1014 ?·m, and an electric resistance value R300 at an applied voltage of 300 V which satisfies the relationship represented by the formula: 0.1?R300/R100?1.

Abstract: In a detector for spectrometry attached to an integrating sphere, a plurality of detection elements having different spectral sensitivity characteristics is arranged side by side in the same plane on a base, and a side cover is provided such that the detection elements receive light. Thus, the measurement light is directly irradiated to the respective detection elements. Accordingly, the detector for spectrometry has a fast response speed and is excellent in the sensitivity characteristics in a wide wavelength region in the near-infrared area.

Abstract: In a detector for spectrometry attached to an integrating sphere, a plurality of detection elements having different spectral sensitivity characteristics is arranged side by side in the same plane on a base, and a side cover is provided such that the detection elements receive light. Thus, the measurement light is directly irradiated to the respective detection elements. Accordingly, the detector for spectrometry has a fast response speed and is excellent in the sensitivity characteristics in a wide wavelength region in the near-infrared area.