Electrophotographic electro-conductive member, electrophotographic image forming apparatus, and process cartridge
An electro-conductive member for an electrophotographic image forming apparatus for which a change in resistance value is small even when a large current is applied at a high voltage for a long period of time is provided. The electro-conductive member includes a support having an electro-conductive outer surface and an electro-conductive layer on the outer surface of the support, in which the electro-conductive layer has a matrix including a cross-linked product of a first rubber and domains dispersed in the matrix, the domains include a cross-linked product of a second rubber different from the first rubber and an electrically conductive agent, and the cross-linked product of the second rubber has, in a molecule, a structural unit represented by Structural Formula (I). [—(CH 2 ) n —O—] Structural Formula (I) In Structural Formula (I), n is an integer of 1 to 3.
1. 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 comprising a matrix including a cross-linked product of a first rubber, and domains dispersed in the matrix;
the domains comprising a cross-linked product of a second rubber different from the first rubber and carbon black; and
the cross-linked product of the second rubber comprising, in a molecule, a structural unit represented by formula (I)
[—(CH 2 ) n —O—] (I), where n is an integer of 1 to 3, wherein
when L is a longitudinal direction length of the electro-conductive layer is denoted and T is a thickness of the electro-conductive layer is denoted, for each cross-section of the electro-conductive layer in a thickness direction at three locations of a center of the electro-conductive layer in a longitudinal direction and L/4 from both ends toward the center of the electro-conductive layer, and
when 15 μm square observation regions are placed at three arbitrary locations in a thickness region from an outer surface of the electro-conductive layer to a depth of 0.1-0.9 T, at least 80% of the number of the domains observed in each of the total of nine observation regions satisfy (1) and (2)
(1) a ratio of a cross-sectional area of the carbon black included in the domain with respect to a cross-sectional area of the domain is at least 20%, and
(2) A/B is 1.00 or more to 1.10 or less when A is a perimeter of the domain and B is an envelope perimeter of the domain.
2. The electrophotographic electro-conductive member according to claim 1 , wherein ρd is 1.0×10 1 to 1.0×10 4 Ω·cm and ρ is 1.0×10 5 to 1.0×10 8 Ω·cm when ρd is a volume resistivity of the domain and ρ is a volume resistivity of the electro-conductive layer.
3. The electrophotographic electro-conductive member according to claim 1 , wherein a volume resistivity μm of the matrix is 1.0×10 8 to 1.0×10 17 Ω·cm.
4. The electrophotographic electro-conductive member according to claim 1 , wherein the cross-linked product of the second rubber comprises a structural unit derived from allyl glycidyl ether.
5. The electrophotographic electro-conductive member according to claim 1 , wherein the cross-linked product of the second rubber is a cross-linked product of an epichlorohydrin-alkylene oxide-allyl glycidyl ether ternary copolymer.
6. The electrophotographic electro-conductive member according to claim 1 , wherein the structural unit represented by formula (I) comprises at least one of an ethylene oxide structural unit and a propylene oxide structural unit.
7. The electrophotographic electro-conductive member according to claim 1 , wherein a DBP absorption amount of the carbon black is 40 to 200 cm 3 /100 g.
8. The electrophotographic electro-conductive member according to claim 1 , wherein an average of a maximum Feret diameter D f of the domains included in each of the domains satisfying (1) and (2) is in a range of 0.1 to 5.0 μm.
9. The electrophotographic electro-conductive member according to claim 1 , wherein an average number of the domains present in the observation regions is 20 to 300.
10. The electrophotographic electro-conductive member according to claim 1 , wherein a ratio of a cross-sectional area of the carbon black with respect to a cross-sectional area of the domains is 30% or less.
11. The electrophotographic electro-conductive member according to claim 1 , wherein the first rubber is acrylonitrile-butadiene rubber.
12. The electrophotographic electro-conductive member according to claim 11 , wherein an acrylonitrile content ratio in the cross-linked product of the first rubber is 15 to 25% by mass.
13. The electrophotographic electro-conductive member according to claim 1 , wherein the electro-conductive member has a roller shape.
14. The electrophotographic electro-conductive member according to claim 1 , wherein the electro-conductive member is a transfer member.
15. An electrophotographic image forming apparatus comprising an electrophotographic electro-conductive member, the 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 comprising a matrix including a cross-linked product of a first rubber, and domains dispersed in the matrix;
the domains comprising a cross-linked product of a second rubber different from the first rubber and carbon black; and
the cross-linked product of the second rubber comprising, in a molecule, a structural unit represented by formula (I)
[—(CH 2 ) n —O—] (I), where n is an integer of 1 to 3, wherein
when L is a longitudinal direction length of the electro-conductive layer is denoted and T is a thickness of the electro-conductive layer is denoted, for each cross-section of the electro-conductive layer in a thickness direction at three locations of a center of the electro-conductive layer in a longitudinal direction and L/4 from both ends toward the center of the electro-conductive layer, and
when 15 μm square observation regions are placed at three arbitrary locations in a thickness region from an outer surface of the electro-conductive layer to a depth of 0.1-0.9 T, at least 80% of the number of the domains observed in each of the total of nine observation regions satisfy (1) and (2)
(1) a ratio of a cross-sectional area of the carbon black included in the domain with respect to a cross-sectional area of the domain is at least 20%, and
(2) A/B is 1.00 or more to 1.10 or less when A is a perimeter of the domain and B is an envelope perimeter of the domain.
16. The electrophotographic image forming apparatus according to claim 15 , wherein the electro-conductive member is configured to function as a transfer member.
17. An electrophotographic process cartridge which is attachable to and detachable from a main body of an electrophotographic image forming apparatus, comprising an electro-conductive member, the 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 comprising a matrix including a cross-linked product of a first rubber, and domains dispersed in the matrix;
the domains comprising a cross-linked product of a second rubber different from the first rubber and carbon black; and
the cross-linked product of the second rubber comprising, in a molecule, a structural unit represented by formula (I)
[—(CH 2 ) n —O—] (I), where n is an integer of 1 to 3, wherein
when L is a longitudinal direction length of the electro-conductive layer is denoted and T is a thickness of the electro-conductive layer is denoted, for each cross-section of the electro-conductive layer in a thickness direction at three locations of a center of the electro-conductive layer in a longitudinal direction and L/4 from both ends toward the center of the electro-conductive layer, and
when 15 μm square observation regions are placed at three arbitrary locations in a thickness region from an outer surface of the electro-conductive layer to a depth of 0.1-0.9 T, at least 80% of the number of the domains observed in each of the total of nine observation regions satisfy (1) and (2)
(1) a ratio of a cross-sectional area of the carbon black included in the domain with respect to a cross-sectional area of the domain is at least 20%, and
(2) A/B is 1.00 or more to 1.10 or less when A is a perimeter of the domain and B is an envelope perimeter of the domain.