Electrophotographic photosensitive member, process cartridge, and electrophotographic apparatus
There is provided an electrophotographic photosensitive member in which the variation in potential during repeated use is reduced. The electrophotographic photosensitive member is the electrophotographic photosensitive member of which an undercoat layer comprises a urethane resin and titanium oxide particles whose primary particle and secondary particle diameters are defined.
1. An electrophotographic photosensitive member, comprising:
an electro-conductive support;
an undercoat layer on the electro-conductive support, the undercoat layer comprising a urethane binder resin and titanium oxide secondary particles, said titanium oxide secondary particles being an aggregate of titanium oxide primary particles; and
a photosensitive layer on the undercoat layer, wherein
the number average particle diameter of the titanium oxide primary particles is 1 to 10 nm, and
the number average particle diameter of the titanium oxide secondary particles is 200 to 500 nm.
2. The electrophotographic photosensitive member according to claim 1 , wherein the titanium oxide primary particles are surface-treated with a silane coupling agent having an amino group.
3. The electrophotographic photosensitive member according to claim 1 , wherein the undercoat layer contains at least one compound selected from the group consisting of Formulae (1) and (2) below
where R a1 to R a8 independently represent a hydrogen atom, a hydroxy group, a halogen atom, an alkyl group, an alkoxy group, a phenyl group, or an amino group), and R b1 to R b10 independently represent a hydrogen atom, a hydroxy group, a halogen atom, an alkyl group, an alkoxy group, a phenyl group, or an amino group.
4. The electrophotographic photosensitive member according to claim 3 , wherein the compound represented by Formulae (1) or (2) is an anthraquinone compound having two or more hydroxy groups or a benzophenone compound having three or more hydroxy groups.
5. The electrophotographic photosensitive member according to claim 1 , wherein a mass ratio (PB) is from 0.5/1.0 to 4.0/1.0, when (P) is the mass of titanium oxide primary particles in the undercoat layer and (B) is the mass of urethane resin in the undercoat layer.
6. The electrophotographic photosensitive member according to claim 1 , wherein a mass ratio (P/B) is from 0.5/1.0 to 3.0/1.0 when (P) is the mass of titanium oxide primary particles in the undercoat layer and (B) is the mass of urethane resin in the undercoat layer.
7. The electrophotographic photosensitive member according to claim 1 , wherein a mass ratio (P/B) is from 1.0/1.0 to 3.0/1.0 when (P) is the mass of titanium oxide primary particles in the undercoat layer and (B) is the mass of urethane resin in the undercoat layer.
8. The electrophotographic photosensitive member according to claim 1 , wherein the thickness of the undercoat layer is 0.5 to 30 μm.
9. The electrophotographic photosensitive member according to claim 1 , wherein the thickness of the undercoat layer is 2 to 30 μm.
10. The electrophotographic photosensitive member according to claim 1 , wherein the thickness of the undercoat layer is 2 to 10 μm.
11. A process cartridge and at least one unit selected from the group consisting of a charging unit, a developing unit, a transferring unit and a cleaning unit, said process cartridge being detachably attachable from a main body of an electrophotographic apparatus and integrally supporting an electrophotographic photosensitive member, the electrophotographic photosensitive member comprises:
an electro-conductive support;
an undercoat layer on the electro-conductive support, the undercoat layer comprising a urethane binder resin and titanium oxide secondary particles, said titanium oxide secondary particles being an aggregate of titanium oxide primary particles; and
a photosensitive layer on the undercoat layer, wherein
the number average particle diameter of the titanium oxide primary particles is 1 to 10 nm, and
the number average particle diameter of the titanium oxide secondary particles is 200 to 500 nm.
12. An electrophotographic apparatus comprising:
a charging unit;
an exposing unit;
a developing unit;
a transferring unit; and
an electrophotographic photosensitive member, the electrophotographic photosensitive member comprising an electro-conductive support, an undercoat layer on the electro-conductive support, and a photosensitive layer on the undercoat layer, wherein
the undercoat layer comprises a urethane binder resin, and titanium oxide secondary particles, said titanium oxide secondary particles being an aggregate of titanium oxide primary particles,
the number average particle diameter of the titanium oxide primary particles is 1 to 10 nm, and
the number average particle diameter of the titanium oxide secondary particles is 200 to 500 nm.
13. The electrophotographic apparatus according to claim 12 , wherein the charging unit is configured to charge the electrophotographic photosensitive member by applying only a direct current voltage to a charging roller disposed so as to abut the electrophotographic photosensitive member.