Electro-conductive member for electrophotography, process cartridge for electrophotography, and electrophotographic image forming apparatus

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 1.0×108 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 1.0×101 to 1.0×104 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/cm3)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.

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 1.0×108 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 1.0×101 to 1.0×104 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/cm3)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.

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 1.0×108 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 1.0×101 to 1.0×104 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/cm3)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.