Electrophotographic photosensitive member, process cartridge, and electrophotographic apparatus

1. An electrophotographic photosensitive member, comprising:

a support;

an undercoat layer;

a photosensitive layer; and

a surface layer,

the undercoat layer containing a binder resin and strontium titanate particles,

the surface layer being a cured film of a composition containing at least one compound selected from the group consisting of a guanamine compound and a melamine compound, and a charge transport material having at least one substituent selected from the group consisting of —OH, —OCH 3 , —NH 2 , —SH, and —COOH,

wherein in a cross-sectional backscattered electron image of the undercoat layer captured using a scanning electron microscope at an acceleration voltage of 2.0 kV, a region originating from the strontium titanate particles has an area of 0.001 μm 2 or more and 0.35 μm 2 or less, and the area of the region originating from the strontium titanate particles is 50% or more and 90% or less of an area of a region originating from the binder resin.

2. The electrophotographic photosensitive member according to claim 1 , wherein the guanamine compound is one selected from the group consisting of a compound represented by general formula (A) and its multimer:

where in general formula (A), R 1 is an alkyl group having 1 or more and 10 or less carbon atoms, a phenyl group having 6 or more and 10 or less carbon atoms, or an alicyclic hydrocarbon group having 4 or more and 10 or less, R 2 to R 5 are each independently a hydrogen atom or —CH 2 —O—R 6 , and where R 6 is a hydrogen atom or an alkyl group having 1 or more and 10 or less carbon atoms.

3. The electrophotographic photosensitive member according to claim 1 , wherein the melamine compound is one selected from the group consisting of a compound represented by general formula (B) and its multimer:

where in general formula (B), R 6 to R 11 are each independently a hydrogen atom, —CH 2 —OH, —CH 2 —O—R 12 , or —O—R 12 , where R 12 is an alkyl group having 1 or more and 5 or less.

4. The electrophotographic photosensitive member according to claim 1 , wherein in the composition, an amount of the at least one compound selected from the group consisting of the guanamine compound and the melamine compound is 0.1% or more by mass and 50.0% or less by mass based on an amount of the charge transport material.

5. A process cartridge attachable to and detachable from a main body of an electrophotographic apparatus, comprising:

an electrophotographic photosensitive member; and

at least one unit selected from the group consisting of a charging unit, a developing unit, a transfer unit, and a cleaning unit, the process cartridge integrally supporting the electrophotographic photosensitive member and the at least one unit,

wherein the electrophotographic photosensitive member comprises:

a support;

an undercoat layer;

a photosensitive layer; and

a surface layer,

wherein the undercoat layer contains a binder resin and strontium titanate particles, and the surface layer is a cured film of a composition containing at least one compound selected from the group consisting of a guanamine compound and a melamine compound, and a charge transport material having at least one substituent selected from the group consisting of —OH, —OCH 3 , NH 2 , —SH, and —COOH, and

wherein in a cross-sectional backscattered electron image of the undercoat layer captured using a scanning electron microscope at an acceleration voltage of 2.0 kV, a region originating from the strontium titanate particles has an area of 0.001 μm 2 or more and 0.35 μm 2 or less, and the area of the region originating from the strontium titanate particles is 50% or more and 90% or less of an area of a region originating from the binder resin.

6. An electrophotographic apparatus, comprising:

an electrophotographic photosensitive member;

a charging unit;

an exposure unit;

a developing unit; and

a transfer unit,

wherein the electrophotographic photosensitive member comprises:

a support;

an undercoat layer;

a photosensitive layer; and

a surface layer, and

wherein the undercoat layer contains a binder resin and strontium titanate particles, and the surface layer is a cured film of a composition containing at least one compound selected from the group consisting of a guanamine compound and a melamine compound, and a charge transport material having at least one substituent selected from the group consisting of —OH, —OCH 3 , —NH 2 , SH, and —COOH, and

wherein in a cross-sectional backscattered electron image of the undercoat layer captured using a scanning electron microscope at an acceleration voltage of 2.0 kV, a region originating from the strontium titanate particles has an area of 0.001 μm 2 or more and 0.35 μm 2 or less, and the area of the region originating from the strontium titanate particles is 50% or more and 90% or less of an area of a region originating from the binder resin.