Electroconductive member, process cartridge, and electrophotographic image forming apparatus

A process cartridge removably detachable to a main body of an electrophotographic image forming apparatus, the process cartridge comprising:

• an electrophotographic photosensitive member;
• and
• a charging member arranged to be able to charge the electrophotographic photosensitive member,
• wherein the charging member is the electroconductive member comprising:
• a support having electro-conductivity;
• and
• an electroconductive layer arranged on an outer surface of the support,
• the electroconductive layer including:
• a matrix containing:
• a crosslinked product of a first rubber;
• and
• first electroconductive particles;
• and
• domains each containing:
• a crosslinked product of a second rubber;
• and
• second electroconductive particles,
• at least a part of the first electroconductive particles being present as a primary particle in the crosslinked product of the first rubber, wherein
• when defining a length of the electroconductive layer in a longitudinal direction as L and defining a thickness of the electroconductive layer as T, and when 15-micrometer square observation regions are put at arbitrary three positions in a thickness region from an outer surface of the electroconductive layer to a depth of 0.1 to 0.9T on each of cross-sections in a thickness direction of the electroconductive layer at three positions including a center of the electroconductive layer in the longitudinal direction and positions of L/4 from both ends of the electroconductive layer to the center,
• an average primary particle diameter d1 of the first electroconductive particles present as a primary particle in the matrix observed in each of the nine observation regions in total is 200 nm or more, and
• an average primary particle diameter d2 of the second electroconductive particles in the domains observed in each of the observation regions is 50 nm or less, and wherein
• 80 number % or more of the domains observed in each of the observation regions satisfy the following requirement (i) and requirement (ii)
• requirement (i)
• a ratio of cross-sectional areas of the second electroconductive particles included in a domain with respect to a cross-sectional area of the domain is 20% or more;
• requirement (ii)
• a circle-equivalent diameter of a domain is 4×d2 or more.

An electrophotographic image forming apparatus comprising:

• an electrophotographic photosensitive member;
• and
• a charging roller arranged to be able to charge the electrophotographic photosensitive member,
• wherein the charging roller is the electroconductive member comprising:
• a support having electro-conductivity;
• and
• an electroconductive layer arranged on an outer surface of the support,
• the electroconductive layer including:
• a matrix containing:
• a crosslinked product of a first rubber;
• and
• first electroconductive particles;
• and
• domains each containing:
• a crosslinked product of a second rubber;
• and
• second electroconductive particles,
• at least a part of the first electroconductive particles being present as a primary particle in the crosslinked product of the first rubber, wherein
• when defining a length of the electroconductive layer in a longitudinal direction as L and defining a thickness of the electroconductive layer as T, and when 15-micrometer square observation regions are put at arbitrary three positions in a thickness region from an outer surface of the electroconductive layer to a depth of 0.1 to 0.9T on each of cross-sections in a thickness direction of the electroconductive layer at three positions including a center of the electroconductive layer in the longitudinal direction and positions of L/4 from both ends of the electroconductive layer to the center,
• an average primary particle diameter d1 of the first electroconductive particles present as a primary particle in the matrix observed in each of the nine observation regions in total is 200 nm or more, and
• an average primary particle diameter d2 of the second electroconductive particles in the domains observed in each of the observation regions is 50 nm or less, and wherein
• 80 number % or more of the domains observed in each of the observation regions satisfy the following requirement (i) and requirement (ii)
• requirement (i)
• a ratio of cross-sectional areas of the second electroconductive particles included in a domain with respect to a cross-sectional area of the domain is 20% or more;
• requirement (ii)
• a circle-equivalent diameter of a domain is 4×d2 or more.