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

1. 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 1.0×10 3 to 1.0×10 8 Ω 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 15 μm square are arbitrary put in a thickness region of each of the cross sections between a depth of 0.1 T to 0.9 T 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) AB 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.

2. The process for forming an electrophotographic electro-conductive member according to claim 1 , wherein a difference in an absolute value of solubility parameter between the first rubber and the second rubber, is 0.4 to 4.0 (J/cm 3 ) 0.5 .

3. The process for forming an electrophotographic electro-conductive member according to claim 1 , wherein the matrix has a volume resistivity ρm of 1.0×10 8 to 1.0×10 17 Ω·cm.

4. The process for forming an electrophotographic electro-conductive member according to claim 1 , wherein the domains satisfying requirements (1) and (2) have an average maximum Feret's diameter Df of 0.1 to 5.0 μm.

5. The process for forming an electrophotographic electro-conductive member according to claim 1 , wherein the proportion satisfying requirement (1) is 25 to 30%.

6. The process for forming an electrophotographic electro-conductive member according to claim 1 , wherein the electro-conductive particle is carbon black.

7. The process for forming an electrophotographic electro-conductive member according to claim 6 , wherein the carbon black has a DBP adsorption amount of 40 to 80 cm 3 /100 g.

8. The process for forming an electrophotographic electro-conductive member according to claim 6 , wherein the carbon black included in each of the domains satisfying requirements (1) and (2) have an arithmetic mean wall-to-wall distance C of 110 to 130 nm, and

σ·m/C is 0.0 to 0.3 where a standard deviation of a wall-to-wall distance of the carbon black is defined as σ·m.

9. The process for forming an electrophotographic electro-conductive member according to claim 1 , wherein each of the protrusions has a height of 50 to 200 nm.

10. The process for forming an electrophotographic electro-conductive member according to claim 1 , wherein an arithmetic mean wall-to-wall distance Dm of the domains exposed to an outer surface of the electrophotographic electro-conductive member to constitute the protrusions is 2.00 μm or less.

11. The process for forming an electrophotographic electro-conductive member according to claim 1 , wherein the matrix has a volume resistivity ρm of 1.0×10 10 to 1.0×10 17 Ω·cm.

12. The process for forming an electrophotographic electro-conductive member according to claim 1 , wherein the matrix has a volume resistivity ρm of 1.0×10 12 to 1.0×10 17 Ω·cm.