Abstract: A magnetic carrier is provided which uses a toner having high coloring power and enables development to be performed at low electric field intensity and can form high quality images while keeping gradation characteristics. The magnetic carrier includes magnetic carrier particles including at least porous magnetic core particles and a resin. The electric field intensity just before the break-down of the magnetic carrier is 1,300 V/cm or more and 5,000 V/cm or less.

Abstract: A magnetic carrier which has magnetic carrier particles each having at least porous magnetic core particles and a resin, in which, in a backscattered electron image of the magnetic carrier particles, photographed with a scanning electron microscope as taken at an accelerating voltage of 2.0 kV, magnetic carrier particles having area proportion S1 found from a specific expression (1) of from 0.5 area % or more to 8.0 area % or less are in a proportion of 80% by number or more in the magnetic carrier, an average proportion Av1 of the total area of portions having a high luminance which come from a metal oxide on the magnetic carrier particles to the total projected area of the magnetic carrier particles is from 0.5 area % or more to 8.0 area % or less, and an average proportion Av2 found from a specific expression (2) is 10.0 area % or less.

Abstract: Provided is a magnetic carrier giving a high quality image free of density variation without the occurrence of fogging or carrier adhesion and having excellent dot reproducibility even during long-term use. The magnetic carrier has magnetic carrier particles produced by filling pores of porous magnetic core particles with a resin. The magnetic carrier contains 80% by number or more of the magnetic carrier particles satisfying the specific conditions (a) and (b) when 18 straight lines passing through a reference point of a cross section of the magnetic carrier particle are drawn at intervals of 10° in a reflected electron image of the cross section of the magnetic carrier particle photographed by a scanning electron microscope.

Abstract: A magnetic carrier and a two-component developer are provided which have remedied blank areas, fog after leaving, carrier sticking during running, and image density variations before and after running. The magnetic carrier has magnetic carrier particles having at least porous magnetic core particles and a resin. The magnetic carrier particles satisfying the specific conditions (a), (b) and (c) where, in a reflected electron image of cross sections of the magnetic carrier particles as photographed with a scanning electron microscope, straight lines that divide a cross section of a magnetic carrier particle into 72 at intervals of 5° are drawn from a reference point of the cross section thereof toward the surface of the magnetic carrier particle; the magnetic carrier particles being contained in an amount of 60% by number or more.

Abstract: A magnetic carrier and two-component developer are provided alleviating coarse images, fogging when printing is done after a copier body is left standing for one week in a high temperature and high humidity environment and carrier adhesion after extensive operation in a low image ratio. The magnetic carrier includes magnetic carrier particles including porous magnetic core particles and a resin, wherein in a mercury intrusion method applied to the porous magnetic core particles, a pore diameter in which a differential pore volume in the specific pore diameter range becomes maximum is in a specific range, and when the maximum value of a differential pore volume in the specific pore diameter range is defined as P1 and the maximum value of a differential pore volume in the specific pore diameter range is defined as P2, P1 is in a specific range and the ratio P2/P1 is in a specific range.

Abstract: Provided a toner including at least: toner particles each containing at least a binder resin, a release agent, and a colorant; and an inorganic fine powder, in which: a degree of aggregation Y1 at a time of compression (200 kpa) of the toner satisfies a relationship of 15?Y1?35, and a degree of aggregation Y2 at a time of non-compression of the toner satisfies a relationship of 7?Y2?15; and a highest endothermic peak of the toner is present in a temperature range of 30 to 200° C. in an endothermic curve measured with a differential scanning calorimeter (DSC), and a peak temperature Tsc (° C.) of the highest endothermic peak satisfies a relationship of 60?Tsc?130.

Abstract: An object of the present invention is to suppress the adhesion of a carrier to an image bearing member and the generation of a flaw in the surface layer of the image bearing member, and to improve the dot reproducibility of an electrostatic latent image, and so on. The object is achieved by a two-component developer containing a magnetic carrier, which contains resin-containing magnetic particles, in which the packed bulk density ?1 is 0.80 to 2.40 and ?1/?2 (?2 represents true density) is 0.20 to 0.42 of the porous magnetic core particles, and a specific resistance of the porous magnetic core particles, an average breaking strength of the magnetic carrier and a toner surface tension constant in a 45-vol % aqueous solution of methanol measured by a capillary suction time method fall into the specific range, respectively.

Abstract: Provided is a toner including: toner particles each containing at least a binder resin and a wax; and an external additive, in which surfaces of the toner particles have an average surface roughness (Ra) measured with a scanning probe microscope of 1.0 nm or more and 30.0 nm or less; and the toner has a surface tension index I for a 45-vol % aqueous solution of methanol measured by a capillary suction time method and calculated from the following equation (1) of 5.0×10?3 N/m or more and 1.0×10?1 N/m or less: I=P?/(A×B×106)??Eq. (1) where I represents the surface tension index (N/m) of the toner, P? represents a capillary pressure (N/m2) of the toner for the 45-vol % aqueous solution of methanol, A represents a specific surface area (m2/g) of the toner, and B represents a true density (g/cm3) of the toner.

Abstract: An object of the present invention is to suppress the adhesion of a carrier to an image bearing member and the generation of a flaw in the surface layer of the image bearing member, and to improve the dot reproducibility of an electrostatic latent image, and soon. The object is achieved by a two-component developer containing a magnetic carrier, which contains resin-containing magnetic particles, in which the packed bulk density ?1 is 0.80 to 2.40 and ?1/?2 (?2 represents true density) is 0.20 to 0.42 of the porous magnetic core particles, and a specific resistance of the porous magnetic core particles, an average breaking strength of the magnetic carrier and a toner surface tension constant in a 45-vol % aqueous solution of methanol measured by a capillary suction time method fall into the specific range, respectively.

Abstract: In a carrier comprising carrier particles; each carrier particle comprising a carrier core and a coat layer for coating the carrier core, the carrier core has a ferrite component containing i) a metal oxide having at least one of metallic elements Mg, Li and Ca, the total-sum content of which is 10 to 40 mole % based on the whole ferrite component, and ii) a metal oxide having at least one of metallic elements Mn, Cu, Cr and Zn, the total-sum content of which is 50 to 4,000 ppm based on the whole ferrite component. The carrier has a volume distribution based 50% particle diameter (D50) of from 15.0 to 55.0 ?m and a degree of surface unevenness of from 1.05 to 1.30, and the coat layer contains particles; the particles having a number-average primary particle diameter of from 10 to 500 nm.

Abstract: A color toner that comprises at least a binder resin, a colorant and a release agent, wherein the binder resin has at least a polyester unit and is synthesized in the presence of a tin compound as a catalyst represented by the general formula (1): (RCOO)2Sn??(1) wherein, R is an alkyl group of 5 to 15 carbon atoms. The toner is excellent in charge build-up, resistance to high temperature offset, color reproducibility and transparency.

Abstract: A yellow toner in which, in a spectral-distribution diagram in which the reflectance (%) is plotted as ordinate and the wavelength (nm) as abscissa, the reflectance determined for a toner in a state of powder ranges from 15% to 20% at a wavelength of 500 nm and ranges from 75% to 80% at a wavelength of 600 nm, a cyan toner in which, in the like spectral-distribution diagram, the reflectance determined for a toner in a state of powder ranges from 30% to 35% at a wavelength of 450 nm and ranges from 35% to 40% at a wavelength of 475 nm, and a magenta toner in which, in the like spectral-distribution diagram, the reflectance determined for a toner in a state of powder ranges from 5% to 10% at a wavelength of 425 nm and ranges from 65% to 70% at a wavelength of 675 nm. These color toners each contain corresponding pigments in specific combination, and promise color reproduction which can ensure the color tones of process inks.

Abstract: To provide a black toner having excellent charging property and transferring property against a severe environmental change. The black toner includes toner particle containing at least a binder resin, carbon black and a releasing agent, wherein: the toner particles have a weight-average particle diameter of 3.5 to 8.0 ?m; total amount of acid value and hydroxyl value of the toner is 30 to 75 mgKOH/g; average circularity of particles contained in the toner having circle-equivalent diameter of 2 ?m or more is 0.915 to 0.960; loss tangent tan? (103 to 104 Hz) of the toner is represented by the following expression: tan? (103 to 104 Hz)?0.0060 where the loss tangent tan? is represented by ??/?? where ?? denotes dielectric loss factor and ?? denotes dielectric constant, and tan? (103 to 104 Hz) denotes the loss tangent in a frequency range of 103 to 104 Hz; and a ratio of tan? (105 Hz) to tan? (5×104 Hz) is represented by the following expression: 1.05?tan? (105 Hz)/tan? (5×104 Hz)?1.

Abstract: In a color toner having toner particles which have toner base particles containing a binder resin, a colorant and a wax, and inorganic fine particles, (i) in the toner base particles, particles having a circle-equivalent diameter of 3.00 ?m or more as measured with a flow type particle image analyzer have an average circularity of from 0.920 or more to less than 0.950, (ii) in the particles having a circle-equivalent diameter of 3.00 ?m or more in the toner base particles, particles having a circularity of 0.960 or more are in a number frequency cumulative value of 40% or less; and (iii) in the particles having a circle-equivalent diameter of 3.00 ?m or more in the toner base particles, particles having a circularity of 0.920 or less are in a number frequency cumulative value of 30% or less. Also disclosed is a full-color image forming method making use of the toner.

Abstract: A yellow toner in which, in a spectral-distribution diagram in which the reflectance (%) is plotted as ordinate and the. wavelength (nm) as abscissa, the reflectance determined for a toner in a state of powder ranges from 15% to 20% at a wavelength of 500 nm and ranges from 75% to 80% at a wavelength of 600 nm, a cyan toner in which, in the like spectral-distribution diagram, the reflectance determined for a toner in a state of powder ranges from 30% to 35% at a wavelength of 450 nm and ranges from 35% to 40% at a wavelength of 475 nm, and a magenta toner in which, in the like spectral-distribution diagram, the reflectance determined for a toner in a state of powder ranges from 5% to 10% at a wavelength of 425 nm and ranges from 65% to 70% at a wavelength of 675 nm. These color toners each contain corresponding pigments in specific combination, and promise color reproduction which can ensure the color tones of process inks.

Abstract: Provided a toner including at least: toner particles each containing at least a binder resin, a release agent, and a colorant; and an inorganic fine powder, in which: a degree of aggregation Y1 at a time of compression (200 kpa) of the toner satisfies a relationship of 15?Y1?35, and a degree of aggregation Y2 at a time of non-compression of the toner satisfies a relationship of 7?Y2?15; and a highest endothermic peak of the toner is present in a temperature range of 30 to 200° C. in an endothermic curve measured with a differential scanning calorimeter (DSC), and a peak temperature Tsc (° C.) of the highest endothermic peak satisfies a relationship of 60?Tsc?130.

Abstract: A yellow toner in which, in a spectral-distribution diagram in which the reflectance (%) is plotted as ordinate and the wavelength (nm) as abscissa, the reflectance determined for a toner in a state of powder ranges from 15% to 20% at a wavelength of 500 nm and ranges from 75% to 80% at a wavelength of 600 nm, a cyan toner in which, in the like spectral-distribution diagram, the reflectance determined for a toner in a state of powder ranges from 30% to 35% at a wavelength of 450 nm and ranges from 35% to 40% at a wavelength of 475 nm, and a magenta toner in which, in the like spectral-distribution diagram, the reflectance determined for a toner in a state of powder ranges from 5% to 10% at a wavelength of 425 nm and ranges from 65% to 70% at a wavelength of 675 nm. These color toners each contain corresponding pigments in specific combination, and promise color reproduction which can ensure the color tones of process inks.

Abstract: To provide a color toner which is effective in mitigating contamination of a charging member, which is good at low temperature fixing in high-speed copying, and which is excellent in blocking resistance and electrification stability in continuous copying. Provided is a color toner containing at least a binder resin, a colorant, and a releasing agent, in which: (i) the binder resin contains at least a polyester unit; (ii) a weight average particle diameter of the color toner is greater than 6.5 ?m and equal to or less than 11 ?m; (iii) an average circularity A of particles in the color toner each having a circle-equivalent diameter of 3 ?m or more satisfies the relationship of 0.915?A?0.960; (iv) a permeability B (%) of the color toner in a 45 vol % aqueous solution of methanol satisfies the relationship of 10?B?70; and (v) an endothermic curve obtained through differential thermal analysis (DSC) measurement of the color toner has one or multiple endothermic peaks in the temperature range of 30 to 200° C.

Abstract: In a carrier comprising carrier particles; each carrier particle comprising a carrier core and a coat layer for coating the carrier core, the carrier core has a ferrite component containing i) a metal oxide having at least one of metallic elements Mg, Li and Ca, the total-sum content of which is 10 to 40 mole % based on the whole ferrite component, and ii) a metal oxide having at least one of metallic elements Mn, Cu, Cr and Zn, the total-sum content of which is 50 to 4,000 ppm based on the whole ferrite component. The carrier has a volume distribution based 50% particle diameter (D50) of from 15.0 to 55.0 ?m and a degree of surface unevenness of from 1.05 to 1.30, and the coat layer contains particles; the particles having a number-average primary particle diameter of from 10 to 500 nm.

Abstract: To provide a black toner having excellent charging property and transferring property against a severe environmental change. The black toner includes toner particle containing at least a binder resin, carbon black and a releasing agent, wherein: the toner particles have a weight-average particle diameter of 3.5 to 8.0 ?m; total amount of acid value and hydroxyl value of the toner is 30 to 75 mgKOH/g; average circularity of particles contained in the toner having circle-equivalent diameter of 2 ?m or more is 0.915 to 0.960; loss tangent tan ? (103 to 104 Hz) of the toner is represented by the following expression: tan ?(103 to 104 Hz)?0.0060 where the loss tangent tan ? is represented by ??/?? where ?? denotes dielectric loss factor and ?? denotes dielectric constant, and tan ? (103 to 104 Hz) denotes the loss tangent in a frequency range of 103 to 104 Hz; and a ratio of tan ? (105 Hz) to tan ? (5×104 Hz) is represented by the following expression: 1.05?tan ?(105 Hz)/tan ?(5×104 Hz)?1.