Abstract: An image forming apparatus includes a magnetic toner, an image bearing member, and a development device. The image bearing member is an amorphous silicon photosensitive drum. The magnetic toner includes toner particles. The toner particles each include a toner mother particle containing a binder resin and a magnetic powder and alumina particles attached to a surface of the toner mother particle. The alumina particles each include a core containing alumina and a conductive layer covering the core. The conductive layer contains antimony tin oxide. The alumina particles have a number average primary particle diameter of at least 0.15 ?m and no greater than 0.50 ?m. The alumina particles have a specific resistance of no greater than 250 ?·cm. The alumina particles have an X-ray intensity ratio of at least 0.25 and no greater than 0.35.

Abstract: A magnetic toner includes toner particles. The toner particles each include a toner mother particle and an external additive attached to a surface of the toner mother particle. The toner mother particles contain a binder resin and a magnetic powder. The external additive includes resin particles as external additive particles. The resin particles have a blocking rate of no greater than 40% by mass. The resin particles have a number average primary particle diameter of at least 40 nm and no greater than 120 nm. A resin constituting the resin particles is a vinyl resin including repeating units represented by general formulas (1) and (2), and a repeating unit derived from a sulfo group-containing vinyl compound. The content of the repeating unit derived from the sulfo group-containing vinyl compound in the vinyl resin is at least 0.1 mol % and no greater than 3.

Abstract: A magnetic toner includes toner particles. The toner particles each include a toner mother particle and an external additive attached to a surface of the toner mother particle. The toner mother particles contain a binder resin and a magnetic powder. The external additive includes resin particles as external additive particles. The resin particles have a blocking rate of no greater than 40% by mass. The resin particles have a number average primary particle diameter of at least 40 nm and no greater than 120 nm. A resin constituting the resin particles is a vinyl resin including repeating units represented by general formulas (1) and (2), and a repeating unit derived from a sulfo group-containing vinyl compound. The content of the repeating unit derived from the sulfo group-containing vinyl compound in the vinyl resin is at least 0.1 mol % and no greater than 3.

Abstract: A toner includes toner particles each including a toner mother particle. The toner mother particles contain a binder resin, a magnetic powder, and conductive titanium oxide particles. The conductive titanium oxide particles have an aspect ratio of at least 5.0. The amount of the conductive titanium oxide particles is at least 2 parts by mass and no greater than 10 parts by mass relative to 100 parts by mass of the binder resin.

Abstract: 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 ?S/m and no greater than 6.0 ?S/m. A degree of aggregation Y160 of the resin particles represented by expression (1) “Y160=100×M160A/M160B” is at least 15% by mass and no greater than 40% by mass.

Abstract: 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 ?S/m and no greater than 6.0 ?S/m. A degree of aggregation Y160 of the resin particles represented by expression (1) “Y160=100×M160A/M160B” is at least 15% by mass and no greater than 40% by mass.

Abstract: A positively chargeable electrostatic latent image developing toner includes a plurality of toner particles each including a toner mother particle and an external additive adhering to a surface of the toner mother particle. The external additive includes metal oxide particles and coat layers that are each disposed over a surface of a corresponding one of the metal oxide particles. The coat layers contain a nitrogen-containing resin. The metal oxide particles contain metal ions having an electronegativity of no greater than 11.

Abstract: The present disclosure relates to an electrostatic latent image developing toner containing a toner particle including a toner core containing a binder resin and a shell layer coating a surface of the toner core. The shell layer contains a unit derived from a monomer of a thermosetting resin, and a unit derived from a thermoplastic resin. The thermosetting resin is one or more resins selected from the group of amino resins consisting of a melamine resin, a urea resin, and a glyoxal resin. The toner particle contains fine particles in an interfacial portion between the toner core and the shell layer, and the fine particles have a charge property opposite to that of the toner, or have a volume resistivity lower than both a volume resistivity of the binder resin and a volume resistivity of the shell layer.

Abstract: A positively chargeable electrostatic latent image developing toner includes a plurality of toner particles each including a toner mother particle and an external additive adhering to a surface of the toner mother particle. The external additive includes metal oxide particles and coat layers that are each disposed over a surface of a corresponding one of the metal oxide particles. The coat layers contain a nitrogen-containing resin. The metal oxide particles contain metal ions having an electronegativity of no greater than 11.

Abstract: The present disclosure relates to an electrostatic latent image developing toner containing a toner particle including a toner core containing a binder resin and a shell layer coating a surface of the toner core. The shell layer contains a unit derived from a monomer of a thermosetting resin, and a unit derived from a thermoplastic resin. The thermosetting resin is one or more resins selected from the group of amino resins consisting of a melamine resin, a urea resin, and a glyoxal resin. The toner particle contains fine particles in an interfacial portion between the toner core and the shell layer, and the fine particles have a charge property opposite to that of the toner, or have a volume resistivity lower than both a volume resistivity of the binder resin and a volume resistivity of the shell layer.

Abstract: In a positively chargeable toner, calcium carbonate fine particles having a certain average primary particle diameter are attached to the surface of toner base particles. The toner base particles contain at least a binder resin and a colorant. The calcium carbonate fine particles are ones which had been subjected to a surface treatment with a positively chargeable surface treating agent and a silicone oil. A mass ratio of the positively chargeable surface treating agent to the silicone oil attached to the surface of the calcium carbonate fine particles is set to be 7:3 to 3:7 in terms of the positively chargeable surface treating agent:the silicone oil.

Abstract: In a positively chargeable toner, calcium carbonate fine particles having a certain average primary particle diameter are attached to the surface of toner base particles. The toner base particles contain at least a binder resin and a colorant. The calcium carbonate fine particles are ones which had been subjected to a surface treatment with a positively chargeable surface treating agent and a silicone oil. A mass ratio of the positively chargeable surface treating agent to the silicone oil attached to the surface of the calcium carbonate fine particles is set to be 7:3 to 3:7 in terms of the positively chargeable surface treating agent:the silicone oil.

Abstract: A non-magnetic monocomponent toner is provided for use in a developing device of a non-contact developing method, and is obtained by externally adding an external additive to cylindrical toner particles having a ratio of a cylindrical length (L) to a cylindrical diameter (D), (L/D), within a range from 1 to 2. The non-magnetic monocomponent toner having excellent developability for use in an electrophotograhic apparatus employing a non-contact developing method.

Abstract: A magnetic toner contains, as a magnetic powder, magnetic iron oxide having an octahedral particle shape and an average particle diameter of 0.21 ?m or larger and containing 18% or more by weight of FeO. The magnetic toner is so prepared as to have a bulk density A (g/cm3) and a magnetic powder content B (% by weight) that fulfill the formulae 0.8?A/B×100?1.6 and 35?B?50. This alleviates the reddishness of images produced with the magnetic toner, and alleviates the disturbance of a thin toner layer on a developing sleeve and thus the fogging resulting therefrom.

Abstract: The magnetic one-component toner of the present invention is used for a developing device having a stainless-steel development sleeve and satisfies the following formulas (i), (ii), (iii) and (iv). The magnetic one-component development is to develop by using the magnetic one-component toner and rotating a stainless-steel development sleeve at a circumferential velocity of not less than 360 mm/second. Thereby, it is possible to inhibit the occurrence of layer irregularity. A ? 11 ( i ) 4 ? B ( ii ) 0.4 ? B A ? 0.8 ( iii ) A × C ? 800 ( iv ) wherein A represents a frictional charge amount (?C/g) after agitating 5 parts by weight of magnetic one-component toner and 95 parts by weight of non-coated ferrite carrier for one minute, B represents a frictional charge amount (?C/g) after agitating 5 parts by weight of magnetic one-component toner and 95 parts by weight of non-coated ferrite carrier for 30 minutes, and C represents a passage rate of toner (%).

Abstract: A magnetic toner contains, as a magnetic powder, magnetic iron oxide having an octahedral particle shape and an average particle diameter of 0.21 ?m or larger and containing 18% or more by weight of FeO. The magnetic toner is so prepared as to have a bulk density A (g/cm3) and a magnetic powder content B (% by weight) that fulfill the formulae 0.8?A/B×100?1.6 and 35?B?50. This alleviates the reddishness of images produced with the magnetic toner, and alleviates the disturbance of a thin toner layer on a developing sleeve and thus the fogging resulting therefrom.

Abstract: A magnetic toner contains, as a magnetic powder, magnetic iron oxide having an octahedral particle shape and an average particle diameter of 0.21 ?m or larger and containing 18% or more by weight of FeO. The magnetic toner is so prepared as to have a bulk density A (g/cm3) and a magnetic powder content B (% by weight) that fulfill the formulae 0.8?A/B×100?1.6 and 35?B?50. This alleviates the reddishness of images produced with the magnetic toner, and alleviates the disturbance of a thin toner layer on a developing sleeve and thus the fogging resulting therefrom.

Abstract: A developing apparatus has a developer supporting member 41 with a surface roughness RZ in the range from 3.0 to 5.5 &mgr;m and a one-component developer T with a bulk density in the range from 0.35 to 0.55 g/ml, and an image is developed by forming a layer of the developer T on the developer supporting member 41. This makes it possible to form a thin toner layer stably despite changes in ambient conditions, and to prevent low image density and fogging. The absolute value of the amount of electric charge with which the developer T is charged is preferably in the range from 3.0 to 10.0 &mgr;C/g. The developer supporting member 41 is made preferably of stainless steel.

Abstract: A magnetic toner contains, as a magnetic powder, magnetic iron oxide having an octahedral particle shape and an average particle diameter of 0.21 &mgr;m or larger and containing 18% or more by weight of FeO. The magnetic toner is so prepared as to have a bulk density A (g/cm3) and a magnetic powder content B (% by weight) that fulfill the formulae 0.8≦A/B×100≦1.6 and 35≦B≦50. This alleviates the reddishness of images produced with the magnetic toner, and alleviates the disturbance of a thin toner layer on a developing sleeve and thus the fogging resulting therefrom.

Abstract: A developing apparatus has a developer supporting member 41 with a surface roughness RZ in the range from 3.0 to 5.5 &mgr;m and a one-component developer T with a bulk density in the range from 0.35 to 0.55 g/ml, and an image is developed by forming a layer of the developer T on the developer supporting member 41. This makes it possible to form a thin toner layer stably despite changes in ambient conditions, and to prevent low image density and fogging. The absolute value of the amount of electric charge with which the developer T is charged is preferably in the range from 3.0 to 10.0 &mgr;C/g. The developer supporting member 41 is made preferably of stainless steel.