Roller for electrphotography and production method thereof, and electrophotographic image forming apparatus
A roller for electrophotography that has a low electric resistance value and that is still further reduced in contaminating property of other member is provided. The roller includes an electro-conductive mandrel and a surface layer having an electro-conductive foam. The electro-conductive foam includes a vulcanized product of an unvulcanized rubber composition including an acrylonitrile-butadiene rubber and a hydrin rubber. The vulcanized product has a matrix-domain structure having a sea phase and an island phase, contains ethylene oxide of 8.0% by mass or more and 20.0% by mass or less based on a total amount of the vulcanized product, and has a spin-spin relaxation time T2 of 750 μs<T2<930 μs.
1. A roller for electrophotography comprising:
an electro-conductive mandrel; and
a surface layer having an electro-conductive foam, wherein
the electro-conductive foam comprises a vulcanized product of an unvulcanized rubber composition comprising an acrylonitrile-butadiene rubber and a hydrin rubber,
the hydrin rubber comprises an epichlorohydrin/ethylene oxide/allyl glycidyl ether terpolymer,
the vulcanized product has a matrix-domain structure comprising a sea phase and an island phase, the sea phase containing a vulcanized acrylonitrile-butadiene rubber, and the island phase containing a vulcanized hydrin rubber,
the vulcanized product contains ethylene oxide of 8.0% by mass or more and 20.0% by mass or less based on a total amount of the vulcanized product, and
the vulcanized product has a spin-spin relaxation time T2, determined by pulse NMR measurement with a hydrogen nucleus as a measurement nucleus, of: 750 μs<T2<930 μs.
2. The roller for electrophotography according to claim 1 , wherein the spin-spin relaxation time T2 is 800 μs≤T2≤900 μs.
3. The roller for electrophotography according to claim 1 , wherein, when an electric resistance value of the roller for electrophotography is defined as R [Ω], Log R is 6.9 or more and 7.7 or less in an environment of a temperature of 23° C. and a relative humidity of 55%.
4. The roller for electrophotography according to claim 1 , wherein an open cell rate of the electro-conductive foam is 70% or more.
5. An electrophotographic image forming apparatus comprising a roller for electrophotography, wherein
the roller for electrophotography comprises an electro-conductive mandrel and a surface layer having an electro-conductive foam,
the electro-conductive foam comprises a vulcanized product of an unvulcanized rubber composition comprising an acrylonitrile-butadiene rubber and a hydrin rubber,
the hydrin rubber comprises an epichlorohydrin/ethylene oxide/allyl glycidyl ether terpolymer,
the vulcanized product has a matrix-domain structure comprising a sea phase and an island phase, the sea phase containing a vulcanized acrylonitrile-butadiene rubber, and the island phase containing a vulcanized hydrin rubber,
the vulcanized product contains ethylene oxide of 8.0% by mass or more and 20.0% by mass or less based on a total amount of the vulcanized product, and
the vulcanized product has a spin-spin relaxation time T2, determined by pulse NMR measurement with a hydrogen nucleus as a measurement nucleus, of: 750 μs<T2<930 μs.
6. The electrophotographic image forming apparatus according to claim 5 , wherein the roller for electrophotography is a transfer roller.