Electro-conductive member, manufacturing method thereof, process cartridge, and electrophotographic image forming apparatus
The electro-conductive member has an electro-conductive support, and an electro-conductive layer, in which the electro-conductive layer has a matrix including a first rubber cross-linked product and domains dispersed in the matrix, each of the domains includes a second rubber cross-linked product and electro-conductive particles, an outer surface of the electro-conductive member has concave portions, a surface of at least a part of the domains is exposed to the outer surface of the electro-conductive member at bottom portions of the concave portions, a volume resistivity of the matrix is greater than 1×10 12 Ωcm, a volume resistivity of the electro-conductive layer is 1×10 5 Ωcm to 1×10 8 Ωcm, and A2 is 20 times or more of A1.
1. An electro-conductive member comprising:
an electro-conductive support; and
an electro-conductive layer,
wherein the electro-conductive layer is a surface layer of the electro-conductive member, and is constituted by a single layer,
the electro-conductive layer has a matrix including a first rubber cross-linked product and domains dispersed in the matrix,
each of the domains includes a second rubber cross-linked product and electro-conductive particles,
an outer surface of the electro-conductive member has concave portions,
a surface of at least a part of the domains is exposed to the outer surface of the electro-conductive member at bottom portions of the concave portions,
a volume resistivity of the matrix is greater than 1.0×10 12 Ωcm,
a volume resistivity of the electro-conductive layer is 1.0×10 5 Ωcm or more to 1.0×10 8 Ωcm or less, and wherein
A2 is 20 times or more of A1
where A1 is a current value when a DC voltage of 80 V is applied between the electro-conductive support and a cantilever of an atomic force microscope which is in contact with a surface of the matrix, constituting the outer surface of the electro-conductive member, and
A2 is a current value when a DC voltage of 80 V is applied between the electro-conductive support and a cantilever of an atomic force microscope which is in contact with surfaces of the domains, constituting the outer surface of the electro-conductive member.
2. The electro-conductive member according to claim 1 ,
wherein among the domains present on the outer surface, a ratio of the domains exposed on the outer surface of the electro-conductive member at the bottom portions of the concave portion is 50% or more.
3. The electro-conductive member according to claim 1 ,
wherein the first rubber is styrene-butadiene rubber.
4. An electrophotographic image forming apparatus comprising:
an electrophotographic photosensitive member; and
a charging member arranged to enable charging of the electrophotographic photosensitive member,
wherein the charging member is an electro-conductive member comprising:
an electro-conductive support; and
an electro-conductive layer,
wherein the electro-conductive layer is a surface layer of the electro-conductive member, and is constituted by a single layer,
the electro-conductive layer has a matrix including a first rubber cross-linked product and domains dispersed in the matrix,
each of the domains includes a second rubber cross-linked product and electro-conductive particles,
an outer surface of the electro-conductive member has concave portions,
a surface of at least a part of the domains is exposed to the outer surface of the electro-conductive member at bottom portions of the concave portions,
a volume resistivity of the matrix is greater than 1.0×10 12 Ωcm,
a volume resistivity of the electro-conductive layer is 1.0×10 5 Ωcm or more to 1.0×10 8 Ωcm or less, and wherein
A2 is 20 times or more of A1
where A1 is a current value when a DC voltage of 80 V is applied between the electro-conductive support and a cantilever of an atomic force microscope which is in contact with a surface of the matrix, constituting the outer surface of the electro-conductive member, and
A2 is a current value when a DC voltage of 80 V is applied between the electro-conductive support and a cantilever of an atomic force microscope which is in contact with surfaces of the domains, constituting the outer surface of the electro-conductive member.
5. A process cartridge which is attachable to and detachable from a main body of an electrophotographic image forming apparatus, the process cartridge comprising:
an electrophotographic photosensitive member; and
a charging member arranged to enable charging of the electrophotographic photosensitive member,
wherein the charging member is an electro-conductive member comprising:
an electro-conductive support; and
an electro-conductive layer,
wherein the electro-conductive layer is a surface layer of the electro-conductive member, and is constituted by a single layer,
the electro-conductive layer has a matrix including a first rubber cross-linked product and domains dispersed in the matrix,
each of the domains includes a second rubber cross-linked product and electro-conductive particles,
an outer surface of the electro-conductive member has concave portions,
a surface of at least a part of the domains is exposed to the outer surface of the electro-conductive member at bottom portions of the concave portions,
a volume resistivity of the matrix is greater than 1.0×10 12 Ωcm,
a volume resistivity of the electro-conductive layer is 1.0×10 5 Ωcm or more to 1.0×10 8 Ωcm or less, and wherein
A2 is 20 times or more of A1
where A1 is a current value when a DC voltage of 80 V is applied between the electro-conductive support and a cantilever of an atomic force microscope which is in contact with a surface of the matrix, constituting the outer surface of the electro-conductive member, and
A2 is a current value when a DC voltage of 80 V is applied between the electro-conductive support and a cantilever of an atomic force microscope which is in contact with surfaces of the domains, constituting the outer surface of the electro-conductive member.
6. A manufacturing method of an electro-conductive member, the method comprising the following steps (A) to (D):
(A) providing a rubber composition for forming a domain including the electro-conductive particles and the second rubber;
(B) providing a rubber composition for forming a matrix including the first rubber;
(C) kneading the rubber composition for forming a domain and the rubber composition for forming a matrix to prepare a rubber composition having a matrix-domain structure; and
(D) extruding the rubber composition having the matrix-domain structure together with an electro-conductive support from a crosshead to coat a periphery of the electro-conductive support with the rubber composition having the matrix-domain structure,
wherein, a ratio of die swell values DS(m)/DS(d) is greater than 1.00, where DS(d) is a die swell value of the rubber composition for forming a domain, and DS(m) is a die swell value of the rubber composition for forming a matrix, and
wherein the electro-conductive member comprising:
an electro-conductive support; and
an electro-conductive layer,
wherein the electro-conductive layer is a surface layer of the electro-conductive member, and is constituted by a single layer,
the electro-conductive layer has a matrix including a first rubber cross-linked product and domains dispersed in the matrix,
each of the domains includes a second rubber cross-linked product and electro-conductive particles,
an outer surface of the electro-conductive member has concave portions,
a surface of at least a part of the domains is exposed to the outer surface of the electro-conductive member at bottom portions of the concave portions,
a volume resistivity of the matrix is greater than 1.0×10 12 Ωcm,
a volume resistivity of the electro-conductive layer is 1.0×10 5 Ωcm or more to 1.0×10 8 Ωcm or less, and wherein
A2 is 20 times or more of A1
where A1 is a current value when a DC voltage of 80 V is applied between the electro-conductive support and a cantilever of an atomic force microscope which is in contact with a surface of the matrix, constituting the outer surface of the electro-conductive member, and
A2 is a current value when a DC voltage of 80 V is applied between the electro-conductive support and a cantilever of an atomic force microscope which is in contact with surfaces of the domains, constituting the outer surface of the electro-conductive member.
7. The method for manufacturing an electro-conductive member according to claim 6 ,
wherein DS(m)/DS(d) is 1.15 or more.