Toner supply roller, developing apparatus, electrophotographic image forming apparatus and process cartridge

An electrophotographic roller, which is a toner supply roller, comprising:

• a conductive substrate;
• and a foamed layer on an outer circumferential surface of the substrate;
• the foamed layer being a surface layer of the electrophotographic roller and having a skeleton including a binder resin which is polyurethane, and at least one conductive particle in the binder resin;
• the polyurethane being a reaction product of polyol and isocyanate, the polyol comprising polyether polyol and the isocyanate comprising at least one member selected from the group consisting of 2,4-tolylenediisocyanate, 2,6-tolylenediisocyanate and 4,4′-diphenylmethane diisocyanate;
• and
• the foamed layer being formed using a temperature-sensitive urethanization catalyst, and having a communication structure with at least one gap opening in an outer surface of the foamed layer, and extending in a thickness direction of the foamed layer, wherein
• at least a portion of an inner wall of the gap is constituted of the skeleton,
• at least a portion of the at least one conductive particle is exposed at the inner wall,
• a thickness T of the foamed layer is 2.0 mm or more,
• an average elastic modulus measured at a surface of the inner wall is 1300 to 2000 MPa, and
• with L being a length in the longitudinal direction of the foamed layer, at respective 4 sites rotated by 90 degrees in a circumferential direction of the foamed layer, at each of 3 sites of a midpoint in a longitudinal direction of the foamed layer, and points each at a distance of L/4 from each opposite end toward the midpoint, a cross section with a total thickness of the foamed layer—in a direction along a circumferential direction of the electrophotographic roller is exposed, where
• for each of the cross sections at a total of 12 sites, the inner wall of the at least one gap present in a region to a depth of 1.0 mm from the outer surface of the foamed layer is observed by a scanning electron microscope, thereby acquiring a secondary electronic image at a magnification of 5000 times, and a resolution of 18 nm/pixel, having 256 gradation steps with the lowest gradation of 0 and the highest gradation of 255, having a contrast of 1200, and an average brightness of 128±16, and in a case where a ratio Rs of a total sum of a number of pixels belonging to brightness of 200 to 255 to a total number of pixels in the secondary electronic image is determined, an average value of Rs at the 12 sites is 0.5% or more, and
• for each of the cross sections at the total of 12 sites, the inner wall of the at least one gap present in a region to a thickness of 1.0 mm from a surface on a side of the foamed layer opposed to the substrate toward the outer surface of the foamed layer is observed by a scanning electron microscope, thereby acquiring a secondary electronic image at a magnification of 5000 times, and a resolution of 18 nm/pixel, having 256 gradation steps with the lowest gradation of 0 and the highest gradation of 255, having a contrast of 1200, and an average brightness of 128±16, and in a case where a ratio Rt of a total sum of a number of pixels belonging to brightness of 200 to 255 to a total number of pixels in the secondary electronic image is determined, an average value of Rt at the 12 sites is 0.5% or more.