There is provided a process cartridge detachably attachable to a main body of an electrophotographic apparatus, the process cartridge including an electrophotographic photosensitive member and a charging member, wherein an outer surface of the charging member is composed of at least a matrix and at least a part of domains, a volume resistivity of the matrix is 1.0×10.sup.5 times or more of a volume resistivity of the domain, an average value Sd of circle equivalent diameters of the domains observed on the outer surface of the charging member is in a predetermined range, the electrophotographic photosensitive member contains a support, a photosensitive layer, and a protective layer in this order and when a surface roughness of the protective layer is measured, each of a protruding valley portion Rvk, a load length ratio Mr2, and Sd/Rvk is in a predetermined range.

A charging roller comprising an electroconductive mandrel and an electroconductive layer as a surface layer, the electroconductive layer including a matrix containing a cross-linked product of a first rubber and domains dispersed in the matrix, each of the domains containing a cross-linked product of a second rubber and an electroconductive particle, the domains each having a volume resistivity lower than a volume resistivity of the matrix, and when sampling a cubic sample of the electroconductive layer having a side of 20.0 μm from a region from an outer surface of the electroconductive layer to a depth of 20.0 μm, 50 number % or more of all the domains in the cubic sample satisfy a specific condition.

Described herein is a liquid electrostatic ink developer assembly comprising a developer roller having a surface coating, the surface coating comprising a polyurethane resin formed from a polyol; a hydroxyl-terminated polysiloxane; and a polyisocyanate. Also, described herein is a liquid electrostatic printing apparatus comprising the liquid electrostatic ink developer assembly.

The electro-conductive member has an electro-conductive support, and an electro-conductive layer, in which the electro-conductive layer has a matrix including a first rubber cross-linked product and domains dispersed in the matrix, each of the domains includes a second rubber cross-linked product and electro-conductive particles, an outer surface of the electro-conductive member has concave portions, a surface of at least a part of the domains is exposed to the outer surface of the electro-conductive member at bottom portions of the concave portions, a volume resistivity of the matrix is greater than 1×10.sup.12 Ωcm, a volume resistivity of the electro-conductive layer is 1×10.sup.5 Ωcm to 1×10.sup.8 Ωcm, and A2 is 20 times or more of A1.

The developing member includes a substrate having an electroconductive outer surface; an insulating resin layer on the outer surface of the substrate; and electrically insulating domains on an outer surface of insulating resin layer, and has an outer surface including a surface of the insulating resin layer and surfaces of the domains, wherein a potential decay time constant of each of the surfaces of the domains is ≥60.0 seconds, and a potential decay time constant of the surface of the electrically insulating resin layer is <6.0 seconds, and assuming that the electrically insulating domains are orthographically projected onto the outer surface of the substrate, to obtain projection images of the respective domains, each of areas of the projection images is defined as S, and each of areas of convex envelopes of the projection images is defined as H, at least one of the domains satisfies 0.05≤S/H≤0.80.

Provided are a developing roll for an electrophotographic device and a method for manufacturing a developing roll for an electrophotographic device, with which toner fusion and toner filming are suppressed. A developing roll for an electrophotographic device includes a shaft body and an elastic body layer formed on an outer circumference of the shaft body. The surface of the elastic body layer has a plurality of large protruding parts having a width of 3.0 to 12 μm and a height of 3.0 to 12 μm, and the side surface of the large protruding part 16 has a plurality of small protruding parts which form convex-concavity having a ten-point average roughness Rz of 2.0 to 4.0 μm.

A developer bearing member including: a rotational shaft; and an elastic layer on an outer circumference surface of the rotational shaft, developer being borne on a surface of the elastic layer, wherein the elastic layer is configured such that a load per unit area of a contact portion between one surface of a flat glass plate and the surface of the elastic layer is to be 5.8 N/mm.sup.2 or more, in a state that the one surface of the flat glass plate being parallel with an axis direction of the rotational shaft and the one surface of the flat glass plate coming into contact with the surface of the elastic layer with a predetermined penetration level, and wherein a ten-point average roughness Rzjis on the surface of the elastic layer is greater than a volume-average particle diameter of a particle of the developer.

The present disclosure relates to a liquid electrophotographic ink developer unit. The unit comprises a developer roller comprising a layer formed from a polymer composition containing a conductive filler, whereby the polymer composition has a specific resistivity of less than 1×10.sup.6 Ω.Math.cm. The unit also comprises a secondary roller that co-operates with the developer roller.

There is provided a process cartridge detachably attachable to a main body of an electrophotographic apparatus, the process cartridge including an electrophotographic photosensitive member and a charging member, wherein an outer surface of the charging member is composed of at least a matrix and at least a part of domains, a volume resistivity of the matrix is 1.010.sup.5 times or more of a volume resistivity of the domain, an average value Sd of circle equivalent diameters of the domains observed on the outer surface of the charging member is in a predetermined range, the electrophotographic photosensitive member contains a support, a photosensitive layer, and a protective layer in this order and when a surface roughness of the protective layer is measured, each of a protruding valley portion Rvk, a load length ratio Mr2, and Sd/Rvk is in a predetermined range.

The developing member includes a substrate having an electroconductive outer surface; an insulating layer on the outer surface of the substrate; and electrically insulating domains on an outer surface of insulating layer, and has an outer surface including a surface of the insulating resin layer and surfaces of the domains, wherein a potential decay time constant of each of the surfaces of the domains is 60.0 seconds, and a potential decay time constant of the surface of the electrically insulating layer is <6.0 seconds, and assuming that the electrically insulating domains are orthographically projected onto the outer surface of the substrate, to obtain projection images of the respective domains, each of areas of the projection images is defined as S, and each of areas of convex envelopes of the projection images is defined as H, at least one of the domains satisfies 0.05S/H0.80.