Abstract: A toner comprising a toner particle, wherein the toner particle includes a toner base particle containing a binder resin and includes a protruded portion on a surface of the toner base particle; the protruded portion comprises an organosilicon polymer and a polyhydric acid metal salt; and the polyhydric acid metal salt is present on a surface of the protruded portion.

Abstract: A toner having both of excellent low-temperature fixability and such high durable developability as to be free from causing any development stripe. The toner is a toner including a toner particle containing a crystalline resin as a binder resin. When a relative permittivity obtained at a time of impedance measurement of the toner under an environment at a temperature of 25° C. and a relative humidity of 50% is represented by ?r, a difference ??r between a relative permittivity ?r(0.01 Hz) at a frequency of 0.01 Hz and a relative permittivity ?r(383 kHz) at a frequency of 383 kHz satisfies a relationship of 0.21?{?r(0.01 Hz)??r(383 kHz)}?0.48.

Abstract: A toner comprising a toner particle, wherein the toner particle includes a toner base particle containing a binder resin and includes a protruded portion on a surface of the toner base particle; the protruded portion comprises an organosilicon polymer and a polyhydric acid metal salt; and the polyhydric acid metal salt is present on a surface of the protruded portion.

Abstract: Provided is a process cartridge detachably attachable to a main body of an electrophotographic apparatus, the process cartridge including: a developing unit including a toner; and an electrophotographic photosensitive member, wherein the toner includes a toner particle, the toner particle has a surface containing a polyvalent acid metal salt particle, and a surface layer of the electrophotographic photosensitive member contains at least one metal oxide particle among an aluminum oxide particle, a silicon dioxide particle, and a tin oxide particle.

Abstract: An external additive for a toner comprising a silica particle surface-treated with a polyhydric acid metal salt particle, wherein the polyhydric acid metal salt particle is particle of a salt of a polyhydric acid and a titanium compound, and a toner comprising a toner particle, and an external additive for a toner on the surface of the toner particle, wherein the external additive for a toner is the above external additive for a toner.

Abstract: A toner comprising a toner particle, wherein the toner particle includes a toner base particle containing a binder resin and includes a protruded portion on a surface of the toner base particle; the protruded portion comprises an organosilicon polymer and a polyhydric acid metal salt; and the polyhydric acid metal salt is present on a surface of the protruded portion.

Abstract: In an image forming apparatus, a fixing member has a surface layer having conductivity. A developer is a toner having a toner particle including a binder resin, a reactant of a polyhydric acid and a compound containing a group 4 element is present on a surface of the toner particle, and Tv/Fv>100 is satisfied where Tv represents a volume resistivity upon being unfixed, and Fv represents a volume resistivity after fixing. A bias applying unit can selectively apply a bias of a positive polarity and a bias of a negative polarity, and applies a bias of the same polarity as the charged polarity of a filler included in a recording material when the recording material passes through a fixing nip portion, and when the recording material does not pass through the fixing nip portion, respectively.

Abstract: A toner containing a toner particle, wherein, when a dielectric loss tangent measured at a frequency of 10 kHz in an impedance measurement on the toner in an environment having a temperature of 50° C. and a relative humidity of 50% RH is designated by tan?50° C.(1), and a dielectric loss tangent measured at a frequency of 10 kHz in an impedance measurement on the toner in an environment having a temperature of 30° C. and a relative humidity of 50% RH after the impedance measurement on the toner in an environment having a temperature of 50° C. and a relative humidity of 50% RH is designated by tan?30° C.(2), tan?50° C.(1) is from 0.015 to 0.050, the relationship tan?50° C.(1)>tan?30° C.(2) is satisfied, and tan?30° C.(2)/tan?50° C.(1) is from 0.25 to 0.66.

Abstract: A toner comprising a toner particle, wherein the toner has G1 of from 5.0×10?13 to 1.0×10?10, and a ratio G2/G1 of G2 to G1 is from 0.10 to 0.60, when a conductivity of the toner measured at a frequency of 0.01 Hz under a pressure of 1,000 kPa is designated by G1 in S/m, and a conductivity of the toner measured at a frequency of 0.01 Hz under a pressure of 100 kPa is designated by G2 in S/m.

Abstract: A developing apparatus comprising a toner and a toner bearing member for bearing the toner, wherein the volume resistivity of the toner is from 1.0×1010 ?·cm to 1.0×1014 ?·cm, a toner bearing member exhibits multiple elementary processes, the volume resistance value Rdr per unit area of the toner bearing member is from 5.0×105 ?/cm2 to 2.0×108 ?/cm2, the capacitance Cdr per unit area of the toner bearing member is from 300 pF/cm2 to 900 pF/cm2, and the capacitance per unit area and volume resistance value of the toner as converted by a parallel plate capacitor model at a thickness of 1.5 times the weight-average particle diameter of the toner are in specific relationships.

Abstract: The present disclosure provides a process cartridge and an electrophotographic apparatus in which fogging is reduced so as to reduce an amount of toner consumed. A process cartridge configured to be detachably attachable to a main body of an electrophotographic apparatus includes a developing unit containing a toner, and an electrophotographic photosensitive member, wherein the toner is a toner that has a toner particle, and has a metal salt of a polyvalent acid at least on a part of a surface of the toner particle; wherein the metal salt of the polyvalent acid includes at least one kind of metal element selected from metal elements belonging to from Group 3 to Group 13, and a surface layer of the electrophotographic photosensitive member contains an acrylic resin or a methacrylic resin.

Abstract: A toner containing a toner particle, wherein, when a dielectric loss tangent measured at a frequency of 10 kHz in an impedance measurement on the toner in an environment having a temperature of 50° C. and a relative humidity of 50% RH is designated by tan ?50° C.(1), and a dielectric loss tangent measured at a frequency of 10 kHz in an impedance measurement on the toner in an environment having a temperature of 30° C. and a relative humidity of 50% RH after the impedance measurement on the toner in an environment having a temperature of 50° C. and a relative humidity of 50% RH is designated by tan ?30° C.(2), tan ?50° C.(1) is from 0.015 to 0.050, the relationship tan ?50° C.(1)>tan ?30° C.(2) is satisfied, and tan ?30° C.(2)/tan ?50° C.(1) is from 0.25 to 0.66.

Abstract: Provided are a process cartridge and an electrophotographic apparatus each of which is reduced in fogging for reducing a toner consumption. Specifically, provided is a process cartridge, which is removably mounted onto a main body of an electrophotographic apparatus, the process cartridge including: a developing unit containing a toner; and an electrophotographic photosensitive member, wherein the toner is a toner including a toner particle, and has a polyvalent acid metal salt on at least part of a surface of the toner particle, wherein the polyvalent acid metal salt includes at least one kind of metal element selected from metal elements belonging to from Group 3 to Group 13, and wherein a surface layer of the electrophotographic photosensitive member contains a resin including a siloxane segment.

Abstract: In an image forming apparatus, a fixing member has a surface layer having conductivity. A developer is a toner having a toner particle including a binder resin, a reactant of a polyhydric acid and a compound containing a group 4 element is present on a surface of the toner particle, and Tv/Fv>100 is satisfied where Tv represents a volume resistivity upon being unfixed, and Fv represents a volume resistivity after fixing. A bias applying unit can selectively apply a bias of a positive polarity and a bias of a negative polarity, and applies a bias of the same polarity as the charged polarity of a filler included in a recording material when the recording material passes through a fixing nip portion, and when the recording material does not pass through the fixing nip portion, respectively.

Abstract: A toner comprising a toner particle, wherein the toner particle includes a binder resin, where a volume resistivity ?·cm of an unfixed solid image on a recording material on which the solid image has been formed using the toner at a toner laid-on level of 0.4 mg/cm2 is denoted by Tv, and a volume resistivity ?·cm of the solid image after fixing by applying heat and pressure to the recording material is denoted by Fv, Tv/Fv?8 is satisfied.

Abstract: A toner including a toner particle, wherein the toner particle includes a toner base particle containing a binder resin, and a shell on the surface of the toner base particle; the shell contains a metal compound and an organosilicon polymer; the shell has at least an exposed portion of the metal compound and an exposed portion of the organosilicon polymer, on the surface of the toner particle; and in an analysis of a cross section of the toner particle by TEM-EDX, Ha (nm) and Hb (nm) which are average distances from the interface of the toner base particle and the shell up to the toner particle surface at the exposed portion of the metal compound and at the exposed portion of the organosilicon polymer, respectively, on the toner particle surface, satisfy Expression (1) below: Hb>Ha+20.0??(1).

Abstract: A toner comprising a toner particle, wherein the toner has G1 of from 5.0×10?13 to 1.0×10?10, and a ratio G2/G1 of G2 to G1 is from 0.10 to 0.60, when a conductivity of the toner measured at a frequency of 0.01 Hz under a pressure of 1,000 kPa is designated by G1 in S/m, and a conductivity of the toner measured at a frequency of 0.01 Hz under a pressure of 100 kPa is designated by G2 in S/m.

Abstract: Provided is a process cartridge detachably attachable to a main body of an electrophotographic apparatus, the process cartridge including: a developing unit including a toner; and an electrophotographic photosensitive member, wherein the toner includes a toner particle, the toner particle has a surface containing a polyvalent acid metal salt particle, and a surface layer of the electrophotographic photosensitive member contains at least one metal oxide particle among an aluminum oxide particle, a silicon dioxide particle, and a tin oxide particle.

Abstract: A toner comprising a toner particle, wherein the toner particle includes a toner base particle containing a binder resin and includes a protruded portion on a surface of the toner base particle; the protruded portion comprises an organosilicon polymer and a polyhydric acid metal salt; and the polyhydric acid metal salt is present on a surface of the protruded portion.

Abstract: A toner comprising a toner particle, wherein the toner particle includes a binder resin, where a volume resistivity ?·cm of an unfixed solid image on a recording material on which the solid image has been formed using the toner at a toner laid-on level of 0.4 mg/cm2 is denoted by Tv, and a volume resistivity ?·cm of the solid image after fixing by applying heat and pressure to the recording material is denoted by Fv, Tv/Fv?8 is satisfied.