A developing member includes a substrate, an elastic layer, and a surface layer in that order. The surface layer contains a urethane resin and a filler. The urethane resin has: the structure represented by structural formula (1) and at least one of the structures represented by structural formula (2) and structural formula (3), between two adjacent urethane linkages; and the structure represented by structural formula (4) and the structure represented by structural formula (5), between two adjacent urethane linkages. The structural formulas (1) to (5) are as follows:

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Provided is a developer carrying member that can stably form a high-quality electrophotographic image. The developer carrying member includes an electroconductive support and a surface layer in the stated order, wherein the surface layer contains a binder resin and electroconductive particles, and a content of the electroconductive particles in a region from a surface of the surface layer opposite to an outer surface thereof on a side facing the electroconductive support to a depth of 150 nm is 1% or more and 25% or less, and wherein the surface layer has a volume resistivity of 1.0×10.sup.−2 Ω.Math.cm or more and 1.0×10.sup.2Ω.Math.cm or less.

A semiconductive roller of the present invention includes a crosslinked product of a rubber composition containing just the two types of rubber of butadiene rubber and epichlorohydrin rubber as rubber components.

Provided is a roller, in particular a conductive roller, capable of suppressing generation of cut debris from a cut surface of an end part of a foam layer in the roller axial direction over a long period of time, and an image forming device using the roller. A roller includes a shaft 1, a foam layer 2 and at least one film layer 3 sequentially provided on the outer periphery of the shaft. Both end parts in the roller axial direction of the foam layer and the film layer are cut, a filler layer 4 is provided on the cut surface of the cut foam layer and the cut film layer, at least the cut surface of the foam layer is covered with the filler layer, and the filler layer contains a water-based urethane resin.

A developer carrying member is disposed below a storage chamber of a frame and has a surface configured such that a plurality of dielectric portions are dispersed on a conductive portion, an upper region of the storage chamber of the frame is enlarged further in a horizontal direction than a lower region in which the developer carrying member is disposed, and the frame has a lower guide surface and includes a curved surface having a tangent plane inclined at a first angle equal to or greater than a degree of an angle of repose of the developer and less than 90 degrees, in an inner wall of the lower region, and an upper guide surface includes a curved surface having a tangent plane inclined at a second angle that is less than the first angle relative to a horizontal plane in an inner wall of the upper region.

A development device includes a development housing, a development roller, a supply roller and a layer thickness regulating member. The development housing stores a nonmagnetic one-component toner. The development roller is formed by a cylindrical elastic body, and moves in a same direction as a rotational direction of a rotatable photosensitive drum at a development nip area while coming into contact with the photosensitive drum. The supply roller is formed by a cylindrical elastic body, and supplies the toner to the development roller and collects the toner from the development roller. The development roller has a surface free energy within a range of 5 mJ/m.sup.2 or more and 27 mJ/m.sup.2 or less.

It is directed to providing a developing roller capable of forming a high-quality electrophotographic image. The developing roller includes a substrate, an electro-conductive elastic layer on the substrate, and a plurality of electrical insulating domains on the electro-conductive elastic layer. The developing roller has a length L of 200 mm or more in a longitudinal direction orthogonal to the circumferential direction thereof. The surface of the developing roller includes the surfaces of the domains and an exposed portion of the electro-conductive elastic layer, the exposed portion being uncovered with the domains. The developing roller has protrusions on the surface thereof, the protrusion being formed by the domains. The electro-conductive elastic layer has a plurality of protrusions at the exposed portion. The developing roller has an Asker C hardness of 50 degrees or more and 90 degrees or less.

A developing apparatus includes a sleeve for carrying a developer including toner and magnetic carrier, the sleeve having a plurality of grooves extending in a longitudinal direction; a magnet provided inside the sleeve, a non-magnetic regulating member, provided spaced from the sleeve, wherein an amount M/S (mg/mm.sup.2) of the developer carried on a unit area of the sleeve after passing by the regulating member, a gap SB (mm) between a free end of the regulating member and the sleeve, a density G (mg/mm.sup.3) of the developer, and a groove ratio α which is a ratio of the grooves in the surface of the sleeve satisfy,
0.1≤M/S (mg/mm.sup.2)≤0.5,
0.2≤SB (mm), and
m/S (mg/mm.sup.2)×¼≤α×{SB (mm)+D (mm)}×G (mg/mm.sup.3)<M/S (mg/mm.sup.2).

The conductive member of this disclosure is formed of a UV cure resin obtained by curing under ultraviolet ray radiation a composition containing a urethane (meth)acrylate oligomer (A), a photo polymerization initiator (B) and an ionic conductive agent (C), wherein: the ionic conductive agent (C) contains an organic boron complex salt and a compound having a structure expressed with the following general formula(1), and a compounding amount of the organic boron complex salt is 0.2 parts by mass or more per 100 parts by mass of a curing component in the composition.

—SO2—NX—SO2—   (1)

(In the general formula (1), X represents an alkali metal.)

Provided is an electrophotographic electroconductive member including an electroconductive support and an electroconductive layer on the support, an electroconductive member is used, in which an electroconductive layer has a matrix comprising a first rubber, and domains dispersed in the matrix, the domains each comprising a second rubber and an electronic electroconductive agent, and for impedance measured by applying an AC voltage with an amplitude of 1 V to the electroconductive layer while varying frequencies between 1.0×10.sup.−2 Hz to 1.0×10.sup.7 Hz under a specific environment, when a double logarithmic plot with a frequency on an abscissa and an impedance on an ordinate is obtained, a slope on a high frequency side is −0.8 or more and —0.3 or less, and the impedance a low frequency side is from 1.0×10.sup.3 to 1.0×10.sup.7Ω.