Electrophotographic image forming apparatus having charge transport layer with matrix-domain structure and charging member having concavity and protrusion

1. An electrophoto graphic image forming apparatus comprising:

an electrophotographic photosensitive member,

a charging unit in contact with the electrophotographic photosensitive member so as to charge the electrophotographic photosensitive member with a charging member, and

a developing unit which supplies toner to the electrophotographic photosensitive member on which an electrostatic latent image is formed, to form a toner image on the electrophotographic photosensitive member;

wherein,

the electrophotographic photosensitive member comprises:

a support,

a charge generation layer disposed on the support, and

a charge transport layer disposed on the charge generation layer;

the charge transport layer is a surface layer of the electrophotographic photosensitive member,

the charge transport layer has a matrix-domain structure comprising a matrix and a domain,

the domain comprises a polyester resin A having:

a structural unit represented by the following Formula (A) and

a structural unit represented by the following Formula (B), and

the matrix comprises:

at least one resin selected from the group consisting of a polyester resin C having a structural unit represented by the following Formula (C) and a polycarbonate resin D having a structural unit represented by the following Formula (D) and

a charge transport substance,

wherein,

the charging member comprises

an electro-conductive substrate, and

an electro-conductive elastic layer;

the electro-conductive elastic layer comprising a binder, and holding a bowl-shaped resin particle having an opening, so that at least a part of the bowl-shaped resin particle is exposed, and

the charging member has

a concavity derived from the opening of the bowl-shaped resin particle on the surface thereof, and a protrusion derived from an edge of the opening of the bowl-shaped resin particle on the surface thereof;

the protrusion on the surface of the charging member coming into contact with the electrophotographic photosensitive member:

wherein,

X 1 represents a m-phenylene group, a p-phenylene group, or a bivalent group having two p-phenylene groups bonded to an oxygen atom;

R 11 to R 14 each independently represent a methyl group, an ethyl group, or a phenyl group; and

n represents the number of repetitions of a structure in brackets, an average value of n in the polyester resin A is 20 or more and 120 or less;

wherein,

X 2 represents a m-phenylene group, a p-phenylene group, or a bivalent group having two p-phenylene groups bonded to an oxygen atom;

wherein,

R 31 to R 38 each independently represent a hydrogen atom or a methyl group;

X 3 represents a m-phenylene group, a p-phenylene group, or a bivalent group having two p-phenylene groups bonded to an oxygen atom; and

Y 3 represents a single bond, a methylene group, an ethylidene group, or a propylidene group;

wherein,

R 41 to R 48 each independently represent a hydrogen atom or a methyl group; and

Y 4 represents a methylene group, an ethylidene group, a propylidene group, a phenylethylidene group, a cyclohexylidene group, or an oxygen atom.

2. The electrophotographic image forming apparatus according to claim 1 , wherein the content of the structural unit represented by Formula (A) based on the total mass of the polyester resin A in the domain is 6% by mass or more and 40% by mass or less.

3. The electrophotographic image forming apparatus according to claim 1 , wherein the content of the structural unit represented by Formula (B) based on the total mass of the polyester resin A in the domain is 60% by mass or more and 94% by mass or less.

4. The electrophotographic image forming apparatus according to claim 1 , wherein the weight average molecular weight of the polyester resin A in the domain is 30,000 or more and 200,000 or less.

5. The electrophotographic image forming apparatus according to claim 1 , wherein the number average particle size of the domain containing the polyester resin A is 100 nm or more and 1,000 nm or less.

6. The electrophotographic image forming apparatus according to claim 1 , wherein the bowl-shaped resin particle to form the protrusion of the charging member is selected from the group consisting of an acrylonitrile resin, a vinyl chloride resin, a vinylidene chloride resin, a methacrylic acid resin, a styrene resin, an urethane resin, an amide resin, a methacrylonitrile resin, an acrylic acid resin, an acrylic acid ester resin, and a methacrylic acid ester resin.

7. The electrophotographic image forming apparatus according to claim 1 , wherein the difference in height between the apex of the protrusion derived from the edge of the opening of the bowl-shaped resin particle and the bottom of the concavity derived from the opening of the bowl-shaped resin particle of the charging member is 5 μm or more and 100 μm or less.

8. The electrophotographic image forming apparatus according to claim 1 , wherein the bowl-shaped resin particle of the charging member has a maximum diameter of 5 μm or more and 150 μm or less.

9. The electrophotographic image forming apparatus according to claim 1 , wherein the bowl-shaped resin particle of the charging member has a ratio of the maximum diameter of the bowl-shaped resin particle to the minimum diameter of the opening ([maximum diameter]/[minimum diameter of opening]) of 1.1 or more and 4.0 or less.

10. The electrophotographic image forming apparatus according to claim 1 , wherein the charging member has a ratio of the maximum diameter of the bowl-shaped resin particle to the difference in height between the apex of the protrusion derived from the edge of the opening of the bowl-shaped resin particle and the bottom of the concavity derived from the opening of the bowl-shaped resin particle ([maximum diameter]/[difference in height]) of 0.8 or more and 3.0 or less.

11. The electrophotographic image forming apparatus according to claim 1 , wherein the bowl-shaped resin particle of the charging member has a shell thickness of 0.1 μm or more and 3 μm or less.

12. The electrophotographic image forming apparatus according to claim 1 , wherein the content of the polyester resin A is 10% by mass or more and 40% by mass or less based on the total mass of all the resins in the charge transport layer.

13. The electrophotographic image forming apparatus according to claim 1 , wherein the surface of the charging member has a ten-point average roughness (Rzjis) of 5 μm or more and 65 μm or less.

14. The electrophotographic image forming apparatus according to claim 1 , wherein the charging member has an average interval of surface irregularities (Sm) of 20 μm or more and 200 μm or less.