Electrophotographic roller, process cartridge, electrophotographic image forming apparatus, and method for manufacturing electrophotographic roller

An electrophotographic roller, comprising:

• a substrate having a conductive outer surface;
• and
• a resin layer that is present on a side of the conductive outer surface of the substrate, wherein
• a volume resistivity is 1.0×106 Q·cm or higher when a metal film is directly provided on an outer surface of the electrophotographic roller and a direct voltage of 50 V is applied thereto under an environment of a temperature of 23° C. and a relative humidity of 50%,
• a maximum value of potentials is lower than 20.0 V when a corona discharger having a 3.0 mm-wide grid part is disposed under an environment of a temperature of 23° C. and a relative humidity of 50% such that a distance between the grid part and the outer surface of the electrophotographic roller reaches 1.0 mm and a width direction of the grid part and an axial direction of the electrophotographic roller coincide with each other, a voltage of 8 kV is applied to the grid part, the corona discharger is relatively moved along the axial direction of the electrophotographic roller at a rate of 400 mm/second to charge the outer surface of the electrophotographic roller, and potentials of the outer surface of the electrophotographic roller are measured 0.06 seconds after passage of the grid part,
• when an object is irradiated with an ultraviolet ray at a light intensity of 800 nW, and a threshold energy of photoelectron emission at which an ionization potential measurement curve rapidly rises is regarded as an ionization potential, the ionization potential of the outer surface of the electrophotographic roller is 5.0 to 5.6 eV, and
• an elastic modulus E1 in a region from the outer surface of the electrophotographic roller to a depth of 0.1 μm that is measured in a thickness-direction cross section of the resin layer of the electrophotographic roller is 200 MPa or higher.