Electrophotographic apparatus, process cartridge, and cartridge set
An electrophotographic apparatus having an electrophotographic photosensitive member, a charging unit, and a developing unit for forming a toner image, wherein the charging unit has a conductive member disposed to be contactable with the electrophotographic photosensitive member, a conductive layer at the surface of the conductive member has a matrix-domain structure, at least a portion of the domains is exposed at the outer surface of the conductive member, the outer surface of the conductive member is constituted at least of the matrix and these domains, a volume resistivity R1 of the matrix is greater than 1.00×10 12 Ω·cm, a volume resistivity R2 of the domains is less than R1, Martens hardness G1 of the matrix and Martens hardness G2 of the domains satisfy a prescribed relationship, and an onset temperature T(A) for a storage elastic modulus E′ of the toner is not more than 80.0° C.
1. An electrophotographic apparatus, comprising:
an electrophotographic photosensitive member;
a charging unit configured to charge a surface of the electrophotographic photosensitive member, the charging unit comprising a conductive member disposed to be contactable with the electrophotographic photosensitive member; and
a developing unit configured to develop an electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a toner to form a toner image on the surface of the electrophotographic photosensitive member, the developing unit containing toner comprising a toner particle that contains a binder resin, a colorant and a crystalline material, wherein
the conductive member comprises a support having a conductive outer surface, and a conductive layer disposed on the outer surface of the support,
the conductive layer comprises a matrix containing a first rubber, and a plurality of domains dispersed in the matrix,
each of the domains contains a second rubber and an electronic conductive agent, at least a portion of the domains being exposed at the outer surface of the conductive member,
the outer surface of the conductive member comprises the matrix and the domains exposed therein,
the matrix has a volume resistivity R1 of at least 2.00×10 12 Ω·cm,
the domains have a volume resistivity R2 that is smaller than R1,
G1<G2, and G1 and G2 are both within 1.0 to 10.0 N/mm 2 where G1 is Martens hardness measured on the matrix that is exposed at the outer surface of the conductive member, and G2 is Martens hardness measured on the domains that are exposed at the outer surface of the conductive member, and
T(A) is not more than 80.0° C. where T(A) is an onset temperature of the storage elastic modulus E′ of the toner according to powder dynamic viscoelastic measurement.
2. The electrophotographic apparatus according to claim 1 , wherein R1 is at least 1.0×10 5 times R2.
3. The electrophotographic apparatus according to claim 1 , wherein an arithmetic average value Dm of distances between adjacent walls of the domains in the conductive layer is 0.15 to 2.00 μm observed in a cross section of the conductive member.
4. The electrophotographic apparatus according to claim 1 , wherein T(A) is at least 45.0° C.
5. The electrophotographic apparatus according to claim 1 , wherein the crystalline material is present at 1 to 60 mass parts per 100 mass parts of the binder resin.
6. The electrophotographic apparatus according to claim 1 , wherein an ester group concentration in the crystalline material is 2.00 to 10.00 mmol/g defined by
[number of moles of ester groups in the crystalline material]/[molecular weight of the crystalline material].
7. The electrophotographic apparatus according to claim 1 , wherein the toner has a relative permittivity εr of at least 2.00.
8. The electrophotographic apparatus according to claim 1 , wherein the first rubber is at least one member selected from the group consisting of butyl rubber, styrene-butadiene rubber and ethylene-propylene-diene rubber, and
the second rubber is at least one member selected from the group consisting of styrene-butadiene rubber, butyl rubber and acrylonitrile-butadiene rubber.
9. The electrophotographic apparatus according to claim 1 , wherein the crystalline material comprises at least one member selected from the group consisting of an ester wax and a crystalline polyester.
10. A process cartridge disposed detachably to a main body of an electrophotographic apparatus, the process cartridge comprising:
a charging unit configured to charge a surface of an electrophotographic photosensitive member, the charging unit comprising a conductive member disposed to be contactable with the electrophotographic photosensitive member; and
a developing unit configured to develop an electrostatic latent image formed on the surface of the electrophotographic photosensitive member with a toner to form a toner image on the surface of the electrophotographic photosensitive member, the developing unit containing toner comprising a toner particle that contains a binder resin, a colorant and a crystalline material, wherein
the conductive member comprises a support having a conductive outer surface, and a conductive layer disposed on the outer surface of the support,
the conductive layer comprises a matrix containing a first rubber, and a plurality of domains dispersed in the matrix,
each of the domains contains a second rubber and an electronic conductive agent, at least a portion of the domains being exposed at the outer surface of the conductive member,
the outer surface of the conductive member comprises the matrix and the domains exposed therein,
the matrix has a volume resistivity R1 of at least 2.00×10 12 Ω·cm,
the domains have a volume resistivity R2 that is smaller than R1,
G1<G2, and G1 and G2 are both within 1.0 to 10.0 N/mm 2 where G1 is Martens hardness measured on the matrix that is exposed at the outer surface of the conductive member, and G2 is Martens hardness measured on the domains that are exposed at the outer surface of the conductive member, and
T(A) is not more than 80.0° C. where T(A) is an onset temperature of the storage elastic modulus E of the toner according to powder dynamic viscoelastic measurement.
11. A cartridge set, comprising:
a first cartridge and a second cartridge that are disposed detachably to a main body of an electrophotographic apparatus;
the first cartridge comprising a charging unit configured to charge a surface of an electrophotographic photosensitive member and having a first frame supporting the charging unit, the charging unit comprises a conductive member disposed to be contactable with the electrophotographic photosensitive member; and
the second cartridge comprising a toner container that accommodates a toner for forming a toner image on the surface of the electrophotographic photosensitive member by developing an electrostatic latent image formed on the surface of the electrophotographic photosensitive member, wherein
the conductive member comprises a support having a conductive outer surface, and a conductive layer disposed on the outer surface of the support,
the conductive layer comprises a matrix containing a first rubber, and a plurality of domains dispersed in the matrix,
each of the domains contains a second rubber and an electronic conductive agent, at least a portion of the domains being exposed at the outer surface of the conductive member,
the outer surface of the conductive member comprising the matrix and the domains exposed therein,
the matrix has a volume resistivity R1 of at least 2.00×10 12 Ω·cm,
the domains have a volume resistivity R2 that is smaller than R1,
G1<G2, and G1 and G2 are both within 1.0 to 10.0 N/mm 2 where G1 is Martens hardness measured on the matrix that is exposed at the outer surface of the conductive member, and G2 is Martens hardness measured on the domains that are exposed at the outer surface of the conductive member, and
T(A) is not more than 80.0° C. where T(A) is an onset temperature of the storage elastic modulus E′ of the toner according to powder dynamic viscoelastic measurement.