Electrophotographic conductive roller, process cartridge, and electrophotographic image forming apparatus
An electrophotographic conductive roller including, in this order, a conductive substrate, an ion-conductive elastic layer, and a surface layer, the surface layer includes a resin and carbon black, and the carbon black in the surface layer has an arithmetic mean Rc of circle-equivalent diameters of 60.0 nm or less and a σc/Rc of 0.000 to 0.650, where σc (nm) is a standard deviation of the circle-equivalent diameter. The carbon black in the surface layer has an arithmetic mean d of inter-wall distances of 80.0 to 150.0 nm and a σd/d of 0.000 to 0.600, where σd (nm) is a standard deviation of inter-wall distances.
1 . An electrophotographic conductive roller comprising, in this order, a conductive substrate, an ion-conductive elastic layer, and a surface layer,
the surface layer comprising a resin and carbon black;
the carbon black in the surface layer having an arithmetic mean Rc of circle-equivalent diameters of 60.0 nm or less and a σc/Rc of 0.000 to 0.650, where σc (nm) is a standard deviation of the circle-equivalent diameters; and
the carbon black in the surface layer having an arithmetic mean d of inter-wall distances of 80.0 to 150.0 nm and a σd/d of 0.000 to 0.600, where σd (nm) is a standard deviation of the inter-wall distances.
2 . The electrophotographic conductive roller according to claim 1 , wherein the resin comprises a polyurethane having a polycarbonate structure.
3 . The electrophotographic conductive roller according to claim 2 , wherein the polyurethane satisfies at least one selected from the group consisting of the following (A), (B), and (C):
(A) having a structure represented by formula (1) below in a molecule;
(B) having one or both structures of a structure represented by formula (2) below and a structure represented by formula (3) below in a molecule; and
(C) having a structure represented by formula (4) below in a molecule:
in formula (1),
R11, R12 and R13 each independently represent a divalent C3-9 hydrocarbon group;
R11 and R12 are hydrocarbon groups different from each other;
R13 is a hydrocarbon group identical to R11 or R12;
m and n are average numbers of moles added, each independently representing a number of 1.0 or greater;
in formula (2),
o and p are average numbers of moles added, each independently representing a number of 1.0 or greater;
in formula (3),
R31 and R32 each independently represent a divalent C3-8 hydrocarbon group, and
q and r are average numbers of moles added, each independently representing a number of 1.0 or greater; and
in formula (4),
R41 represents a divalent C6-9 hydrocarbon group, and
s is an average number of moles added, representing a number of 1.0 or greater.
4 . The electrophotographic conductive roller according to claim 1 , wherein
the surface layer further comprises at least one selected from the group consisting of a compound represented by formula (5) below, a compound represented by formula (6) below, and a compound represented by formula (7) below:
in formula (5), R51 represents a monovalent C1-12 hydrocarbon group, and t and u are average numbers of moles added, each independently representing a number of 1.0 or greater;
in formula (6), R61 represents a monovalent C1-8 hydrocarbon group, and v and w are average numbers of moles added, each independently representing a number of 1.0 or greater; and
in formula (7), R71 represents a monovalent C1-12 hydrocarbon group, and x represents an average number of moles added, representing a number of 1.0 or greater.
5 . The electrophotographic conductive roller according to claim 1 , wherein
when a corona discharger having a grid portion with 3.0 mm in width is placed under an environment at a temperature of 23° C. and a relative humidity of 50% such that a distance between the grid portion and an outer surface of the electrophotographic conductive roller be 1.0 mm and a direction of the width of the grid be aligned with an axial direction of the electrophotographic conductive roller, then a voltage of 8 kV is applied to the grid portion and the corona discharger is relatively moved along the axial direction of the electrophotographic conductive roller at a speed of 400 mm/sec to charge the outer surface of the electrophotographic conductive roller, and a potential of the outer surface at 0.06 seconds after passage of the grid is measured, a maximum value of the potential is less than 20.0 V.
6 . A process cartridge configured to be attachable to and detachable from a main body of an electrophotographic image forming apparatus, comprising:
the electrophotographic conductive roller according to claim 1 .
7 . An electrophotographic image forming apparatus comprising a photoreceptor and a developing roller that supplies a developer to an electrostatic latent image formed on the photoreceptor, wherein
the developing roller is the electrophotographic conductive roller according to claim 1 .