| CPC G03G 9/09725 (2013.01) [G03G 9/0819 (2013.01); G03G 15/0808 (2013.01); G03G 21/1814 (2013.01)] | 7 Claims |
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1. A process cartridge detachably attachable to an electrophotographic apparatus main body, the process cartridge comprising:
an electrophotographic photosensitive member;
a toner comprising a toner particle and an external additive A, the external additive A being a silica particle having a major diameter of 40 to 400 nm, with a coverage of the external additive A with respect to a surface of the toner particle being at least 3.0%; and
a developing roller comprising an electroconductive substrate and a single-layered surface layer containing a binder resin on the substrate, wherein
a surface layer of the electrophotographic photosensitive member has a Martens hardness of 245 to 300 N/mm2 as measured with an indentation force of 7 mN,
E1≥200 MPa and 10 MPa≤E2≤150 MPa, when E1 is an elastic modulus of the binder resin in a first region, the first region being a region from an outer surface of the single-layered surface layer to a depth of 0.1 μm, and E2 is an elastic modulus of the binder resin in a second region, the second region being a region from a depth of 1.0 to 1.1 μm from the outer surface as measured in a cross section in a thickness direction of the single-layered surface layer, and
the elastic modulus in the second region continuously decreases from that in the first region.
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