Electro-conductive member for electrophotography, process cartridge for electrophotography, and electrophotographic image forming apparatus
The electro-conductive member has an electro-conductive support, and an electro-conductive layer in this order, the electro-conductive layer including a matrix and domains, the matrix constituted by a first rubber composition containing a cross-linked product of a first rubber, the domains having electro-conductivity, and dispersed in the matrix, each of the domains constituted by a second rubber composition containing a cross-linked product of a second rubber and an electro-conductive particle, the first rubber and the second rubber being diene-based rubbers, the first rubber having at least one monomer unit, the second rubber having at least one monomer unit different from the monomer unit which the first rubber has; a difference of absolute values of SP values between the first rubber and the second rubber is 0.2 (J/cm 3 ) 0.5 to 4.0 (J/cm 3 ) 0.5 ; and a tan δ1/tan δ2 is 0.45 to 2.00.
1. An electro-conductive member for electrophotography, comprising:
an electro-conductive support and an electro-conductive layer in this order;
the electro-conductive layer comprising a matrix and domains, the matrix having a volume resistivity of 1.0×10 8 Ω·cm or higher, and comprising a first rubber composition that contains a cross-linked product of a first rubber; and
the domains being electro-conductive and dispersed in the matrix, each of the domains having a volume resistivity of 1.0×10 1 to 1.0×10 4 Ω·cm, and comprising a second rubber composition that contains a cross-linked product of a second rubber and an electro-conductive particle, wherein
the first rubber is acrylonitrile-butadiene rubber and the second rubber is styrene-butadiene rubber, or the first rubber is styrene-butadiene rubber and the second rubber is acrylonitrile-butadiene rubber,
a difference of absolute values of solubility parameters (SP values) between the first and second rubbers is 0.2 to 4.0 (J/cm 3 ) 0.5 ,
tan δ1/tan δ2 is 0.45 to 2.00, where tan δ1 and tan δ2 are respectively loss factors of the first and second rubber compositions measured at 23° C., a relative humidity of 50% and a frequency of 80 Hz, and
the amount of the electro-conductive particles in the domains is 50 to 150 parts by mass per 100 parts by mass of the second rubber.
2. The electro-conductive member according to claim 1 , wherein a content ratio of a monomer unit derived from styrene in the styrene-butadiene rubber is 18 to 40% by mass.
3. The electro-conductive member according to claim 1 , wherein a content ratio of a monomer unit derived from acrylonitrile in the acrylonitrile-butadiene rubber is 18 to 40% by mass.
4. The electro-conductive member according to claim 1 , wherein a volume fraction of the domain in the electro-conductive layer is 10 to 40% by volume.
5. The electro-conductive member according to claim 1 , wherein the electro-conductive particle is carbon black.
6. The electro-conductive member according to claim 1 , wherein the electro-conductive layer comprises a cross-linked body of a rubber mixture for forming the electro-conductive layer, the rubber mixture comprising the first and second rubbers, the electro-conductive particle, sulfur and a vulcanization accelerator, and
the vulcanization accelerator comprises a thiazole-based compound.
7. The electro-conductive member according to claim 6 , wherein the thiazole-based compound is a sulfenamide-based compound.
8. A process cartridge that is detachably attachable to a main body of an electrophotographic image forming apparatus, comprising:
an electrophotographic photosensitive member;
an electro-conductive member for electrophotography, the electro-conductive member comprising an electro-conductive support and an electro-conductive layer in this order;
the electro-conductive layer comprising a matrix and domains, the matrix having a volume resistivity of 1.0×10 8 Ω·cm or higher, and comprising a first rubber composition that contains a cross-linked product of a first rubber; and
the domains being electro-conductive; and dispersed in the matrix, each of the domains having a volume resistivity of 1.0×10 1 to 1.0×10 4 Ω·cm, and comprising a second rubber composition that contains a cross-linked product of a second rubber and an electro-conductive particle, wherein
the first rubber is acrylonitrile-butadiene rubber and the second rubber is styrene-butadiene rubber, or the first rubber is styrene-butadiene rubber and the second rubber is acrylonitrile-butadiene rubber,
a difference of absolute values of solubility parameters (SP values) between the first and second rubbers is 0.2 to 4.0 (J/cm 3 ) 0.5 ,
tan δ1/tan δ2 is 0.45 to 2.00, where tan δ1 and tan δ2 are respectively loss factors of the first and second rubber compositions measured at 23° C., a relative humidity of 50% and a frequency of 80 Hz, and
the amount of the electro-conductive particles in the domains is 50 to 150 parts by mass per 100 parts by mass of the second rubber.
9. The process cartridge according to claim 8 , wherein the electro-conductive member is a charging member that is configured to charge the electrophotographic photosensitive member.
10. An electrophotographic image forming apparatus, comprising:
an electro-conductive member, the electro-conductive member comprising an electro-conductive support and an electro-conductive layer in this order;
the electro-conductive layer comprising a matrix and domains, the matrix having a volume resistivity of 1.0×10 8 Ω·cm or higher, and comprising a first rubber composition that contains a cross-linked product of a first rubber; and
the domains being electro-conductive and dispersed in the matrix, each of the domains having a volume resistivity of 1.0×10 1 to 1.0×10 4 Ω·cm, and comprising a second rubber composition that contains a cross-linked product of a second rubber and an electro-conductive particle, wherein
the first rubber is acrylonitrile-butadiene rubber and the second rubber is styrene-butadiene rubber, or the first rubber is styrene-butadiene rubber and the second rubber is acrylonitrile-butadiene rubber,
a difference of absolute values of solubility parameters (SP values) between the first and second rubbers is 0.2 to 4.0 (J/cm 3 ) 0.5 ,
tan δ1/tan δ2 is 0.45 to 2.00, where tan δ1 and tan δ2 are respectively loss factors of the first and second rubber compositions measured at 23° C., a relative humidity of 50% and a frequency of 80 Hz, and
the amount of the electro-conductive particles in the domains is 50 to 150 parts by mass per 100 parts by mass of the second rubber.
11. An electro-conductive member for electrophotography, comprising:
an electro-conductive support and an electro-conductive layer in this order;
the electro-conductive layer comprising a matrix and domains, the matrix having a volume resistivity of 1.0×10 8 Ω·cm or higher, and comprising a first rubber composition that contains a cross-linked product of a first rubber; and
the domains being electro-conductive and dispersed in the matrix, each of the domains having a volume resistivity of 1.0×10 1 to 1.0×10 4 Ω·cm, and comprising a second rubber composition that contains a cross-linked product of a second rubber and an electro-conductive particle, wherein
the first rubber is styrene-butadiene rubber and the second rubber is acrylonitrile-butadiene rubber,
a difference of absolute values of solubility parameters (SP values) between the first and second rubbers is 0.2 to 4.0 (J/cm 3 ) 0.5 , and
tan δ1/tan δ2 is 0.45 to 2.00, where tan δ1 and tan δ2 are respectively loss factors of the first and second rubber compositions measured at 23° C., a relative humidity of 50% and a frequency of 80 Hz.