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

1 . 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 1.0×10 6 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 E 1 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.

2 . The electrophotographic roller according to claim 1 , wherein the resin layer comprises a crosslinked urethane resin and a crosslinked acrylic resin.

3 . The electrophotographic roller according to claim 2 , wherein the crosslinked acrylic resin comprises at least one member selected from the group consisting of silicone and fluorine in a molecule.

4 . The electrophotographic roller according to claim 3 , wherein at least one of a proportion of a detection value of Si and a proportion of a detection value of F based on a total of detection values of F, C, O, Si and N when an outer surface of the resin layer is measured by electron spectroscopy for chemical analysis is 5.0 to 15.0 Atomic %, and

neither the proportion of the detection value of Si nor the proportion of the detection value of F exceed 15.0 Atomic %.

5 . The electrophotographic roller according to claim 2 , wherein the crosslinked urethane resin and the crosslinked acrylic resin form an interpenetrating polymer network structure in the resin layer.

6 . The electrophotographic roller according to claim 1 , wherein an elastic modulus E 2 is 1 to 100 MPa in a region 1.0 to 1.1 μm deep from the outer surface of the electrophotographic roller measured in a thickness-direction cross section of the resin layer of the electrophotographic roller.

7 . The electrophotographic roller according to claim 1 , wherein an outer surface of the resin layer is the outer surface of the electrophotographic roller.

8 . The electrophotographic roller according to claim 1 , wherein the electrophotographic roller is a developing roller that is configured to supply a toner to an electrostatic latent image formed on a photosensitive member.

9 . A process cartridge that is configured to be detachable from a main body of an electrophotographic image forming apparatus, the process cartridge comprising:

a toner;

a developing roller;

a toner layer thickness-regulating member that is at least partially conductive, and is configured to contact the developing roller, and regulate a layer thickness of the toner that is carried on the developing roller, and

a contact point electrically connected to the toner layer thickness-regulating member, wherein

the contact point is electrically connected to a main body contact point of the main body of the electrophotographic image forming apparatus and is configured to enable providing a predetermined voltage to the toner layer thickness-regulating member when the process cartridge has been mounted in the main body of the electrophotographic image forming apparatus, and

the developing roller is the electrophotographic roller according to claim 1 .

10 . The process cartridge according to claim 9 , wherein the toner is a negatively-charged toner.

11 . An electrophotographic image forming apparatus, comprising:

a photosensitive member;

a toner; and

a developing roller configured to supply the toner to an electrostatic latent image formed on the photosensitive member, wherein

the developing roller is the electrophotographic roller according to claim 1 .

12 . The electrophotographic image forming apparatus according to claim 11 , wherein the toner is a negatively-charged toner.

13 . A method for manufacturing the electrophotographic roller according to claim 1 , comprising the steps of:

preparing the substrate having a conductive outer surface; and

forming the resin layer on a side of the outer surface of the substrate, comprising applying and curing an urethane raw material mixture comprising an urethane raw material that forms the crosslinked urethane resin and a surface modifier, to obtain a crosslinked urethane resin, wherein

the surface modifier has a weight-average molecular weight Mw of 200 to 3000.