Electrophotographic electro-conductive member, process cartridge, and electrophotographic image forming apparatus

A process for producing an electrophotographic electro-conductive member, comprising:

• a support having an electro-conductive outer surface;
• and
• an electro-conductive layer on the outer surface of the support;
• the electro-conductive layer having a matrix with domains dispersed therein;
• the matrix comprising a cross-linked product of a first rubber;
• the domains each including a cross-linked product of a second rubber and an electro-conductive particle, at least some of the domains being exposed to an outer surface of the electrophotographic electro-conductive member to constitute protrusions on the outer surface of the electrophotographic electro-conductive member;
• the outer surface of the electrophotographic electro-conductive member comprising the matrix and the domains that are exposed to the outer surface of the electrophotographic electro-conductive member, wherein
• the electrophotographic electro-conductive member has an impedance of 1.0×103 to 1.0×108Ω obtained by applying an alternating current voltage having an amplitude of 1 V and a frequency of 1.0 Hz between the outer surface of the support and a platinum electrode directly provided on the outer surface of the electrophotographic electro-conductive member under an environment of a temperature of 23° C. and a relative humidity of 50%, and
• when defining a length of the electro-conductive layer in a longitudinal direction as L and a thickness of the electro-conductive layer as T, obtaining cross sections of the electro-conductive layer in a thickness direction thereof at a center position of the electro-conductive layer in the longitudinal direction and two positions corresponding to L/4 from both ends of the electro-conductive layer to the center of the electro-conductive layer in the longitudinal direction, and assuming that three observation areas each having a m square are arbitrary put in a thickness region of each of the cross sections between a depth of 0.1T to 0.9T from the outer surface of the electro-conductive layer, 80% or more of domains observed in the respective nine observation areas in total satisfy the following requirements (1) and (2):
• (1) a proportion of a cross-sectional area of the electro-conductive particle included in a domain to be judged among the domains included in the observation areas to a cross-sectional area of the domain is 20% or more;
• and
• (2) A/B is 1.00 to 1.10, where A is a perimeter of the domain, and B is an envelope perimeter of the domain, the process comprising the steps of:
• providing a rubber mixture for forming the domains, including carbon black and the second rubber by kneading the carbon black and the second rubber;
• providing a rubber mixture for forming the matrix, including the first rubber;
• kneading the rubber mixture for forming the domains and the rubber mixture for forming the matrix to prepare a rubber composition having a matrix-domain structure;
• forming a layer of the rubber composition on a surface of the electroconductive support;
• and
• curing the layer of the rubber composition on the surface of the electroconductive support, and then grinding a surface of the layer of the rubber composition which has been cured so as to expose the domains to the outer surface of the electrophotographic electro-conductive member to constitute protrusions on the outer surface of the electrophotographic electro-conductive member.