Electrophotographic photosensitive member, process cartridge, and image forming apparatus

1. An electrophotographic photosensitive member comprising a conductive substrate and a photosensitive layer, wherein

the photosensitive layer is a single-layer photosensitive layer and contains a charge generating material, a hole transport material, an electron transport material, and a binder resin,

the binder resin includes a polyarylate resin,

the polyarylate resin is represented by general formula (1) shown below,

the hole transport material is represented by general formula (HTM1), general formula (HTM2), general formula (HTM3), general formula (HTM4), general formula (HTM5), general formula (HTM6), or general formula (HTM7) shown below,

a scratch resistant depth of the photosensitive layer is no greater than 0.50 μm, and

a Vickers hardness of the photosensitive layer is at least 17.0 HV,

where in general formula (1),

Q 1 , Q 2 , Q 3 , and Q 4 each represent, independently of one another, a methyl group or a hydrogen atom,

r, s, t, and u each represent, independently of one another, a number greater than or equal to 15 and less than or equal to 35,

r+s+t+u=100,

r+t=s+u,

X and Y each represent, independently of one another, a divalent group represented by chemical formula (2A), chemical formula (2B), chemical formula (2C), or chemical formula (2D) shown below, and

X and Y are different from each other,

in general formula (HTM1),

R 1 , R 2 , R 3 , and, R 4 each represent, independently of one another, an alkyl group having a carbon number of at least 1 and no greater than 6,

a1, a2, a3, and a4 each represent, independently of one another, an integer of at least 0 and no greater than 5,

when a1 represents an integer of at least 2 and no greater than 5, chemical groups R 1 may be the same as or different from one another,

when a2 represents an integer of at least 2 and no greater than 5, chemical groups R 2 may be the same as or different from one another,

when a3 represents an integer of at least 2 and no greater than 5, chemical groups R 3 may be the same as or different from one another, and

when a4 represents an integer of at least 2 and no greater than 5, chemical groups R 4 may be the same as or different from one another,

in general formula (HTM2), R 5 , R 6 , R 7 , and R 8 each represent, independently of one another, a hydrogen atom or an alkyl group having a carbon number of at least 1 and no greater than 6,

in general formula (HTM3),

R 9 , R 10 , R 11 , and R 12 each represent, independently of one another, an alkyl group having a carbon number of at least 1 and no greater than 6,

b1, b2, b3, and b4 each represent, independently of one another, an integer of at least 0 and no greater than 5,

when b1 represents an integer of at least 2 and no greater than 5, chemical groups R 9 may be the same as or different from one another,

when b2 represents an integer of at least 2 and no greater than 5, chemical groups R 10 may be the same as or different from one another,

when b3 represents an integer of at least 2 and no greater than 5, chemical groups R 11 may be the same as or different from one another, and

when b4 represents an integer of at least 2 and no greater than 5, chemical groups R 12 may be the same as or different from one another,

in general formula (HTM4),

R 13 , R 14 , R 15 , and R 16 each represent, independently of one another, an alkyl group having a carbon number of at least 1 and no greater than 6,

c1, c2, c3, and c4 each represent, independently of one another, an integer of at least 0 and no greater than 5,

when c1 represents an integer of at least 2 and no greater than 5, chemical groups R 13 may be the same as or different from one another,

when c2 represents an integer of at least 2 and no greater than 5, chemical groups R 14 may be the same as or different from one another,

when c3 represents an integer of at least 2 and no greater than 5, chemical groups R 15 may be the same as or different from one another, and

when c4 represents an integer of at least 2 and no greater than 5, chemical groups R 16 may be the same as or different from one another,

in general formula (ETM5), R 17 , R 18 , R 19 , R 20 , and R 21 each represent, independently of one another, a hydrogen atom or an alkyl group having a carbon number of at least 1 and no greater than 6,

in general formula (HTM6),

R 22 , R 23 , and R 24 each represent, independently of one another, an alkyl group having a carbon number of at least 1 and no greater than 6,

d1, d2, and d3 each represent, independently of one another, an integer of at least 0 and no greater than 5,

when d1 represents an integer of at least 2 and no greater than 5, chemical groups R 22 may be the same as or different from one another,

when d2 represents an integer of at least 2 and no greater than 5, chemical groups R 23 may be the same as or different from one another,

when d3 represents an integer of at least 2 and no greater than 5, chemical groups R 24 may be the same as or different from one another, and

R 25 represents a hydrogen atom or an alkyl group having a carbon number of at least 1 and no greater than 6, and

in general formula (HTM7),

R 26 , R 27 , and R 28 each represent, independently of one another, an alkyl group having a carbon number of at least 1 and no greater than 6,

e1, e2, and e3 each represent, independently of one another, an integer of at least 0 and no greater than 5,

when e1 represents an integer of at least 2 and no greater than 5, chemical groups R 26 may be the same as or different from one another,

when e2 represents an integer of at least 2 and no greater than 5, chemical groups R 27 may be the same as or different from one another,

when e3 represents an integer of at least 2 and no greater than 5, chemical groups R 28 may be the same as or different from one another, and

R 29 , R 30 , and R 31 each represent, independently of one another, a hydrogen atom or an aryl group having a carbon number of at least 6 and no greater than 14.

2. The electrophotographic photosensitive member according to claim 1 , wherein

in general formula (1), X and Y each represent, independently of one another, the divalent group represented by chemical formula (2A), chemical formula (2B), or chemical formula (2D).

3. The electrophotographic photosensitive member according to claim 2 , wherein

in general formula (1), X represents the divalent group represented by chemical formula (2D), and Y represents the divalent group represented by chemical formula (2A) or chemical formula (2B).

4. The electrophotographic photosensitive member according to claim 1 , wherein

in general formula (1), Q 1 , Q 2 , Q 3 , and Q 4 each represent a methyl group.

5. The electrophotographic photosensitive member according to claim 1 , wherein

in general formula (1), r, s, t, and u each represent, independently of one another, a number greater than or equal to 20 and less than or equal to 30.

6. The electrophotographic photosensitive member according to claim 1 , wherein

the polyarylate resin is represented by chemical formula (R-1), chemical formula (R-2), chemical formula (R-3), chemical formula (R-4), chemical formula (R-5), chemical formula (R-6), chemical formula (R-7), chemical formula (R-8), or chemical formula (R-9) shown below

7. The electrophotographic photosensitive member according to claim 1 , wherein

the hole transport material is represented by general formula (HTM1), general formula (HTM2), or general formula (HTM6).

8. The electrophotographic photosensitive member according to claim 1 , wherein

in general formula (HTM1), a1 and a3 each represent 1, and a2 and a4 each represent 0,

in general formula (HTM2), R 5 and R 6 each represent, independently of one another, an alkyl group having a carbon number of at least 1 and no greater than 6, and R 7 and R 8 each represent a hydrogen atom,

in general formula (HTM3), b1 and b3 each represent 1, and b2 and b4 each represent 0,

in general formula (HTM4), c1 and c2 each represent 1, and c3 and c4 each represent 0,

in general formula (ETM5), R 17 , R 18 , R 19 , R 20 , and R 21 each represent, independently of one another, an alkyl group having a carbon number of at least 1 and no greater than 6,

in general formula (HTM6), d1, d2, and d3 each represent 0, and R 25 represents a hydrogen atom, and

in general formula (HTM7), e1, e2, and e3 each represent, independently of one another, 0 or 1.

9. The electrophotographic photosensitive member according to claim 8 , wherein

the hole transport material is represented by chemical formula (HTM1-1), chemical formula (HTM2-1), chemical formula (HTM3-1), chemical formula (HTM4-1), chemical formula (HTM5-1), chemical formula (HTM6-1), chemical formula (HTM7-1), or chemical formula (HTM7-2) shown below

10. The electrophotographic photosensitive member according to claim 1 , wherein

the charge generating material includes X-form metal-free phthalocyanine.

11. A process cartridge comprising the electrophotographic photosensitive member according to claim 1 .

12. An image forming apparatus comprising:

an image bearing member;

a charger configured to charge a surface of the image bearing member;

a light exposure section configured to expose the charged surface of the image bearing member to light to form an electrostatic latent image on the surface of the image bearing member;

a development section configured to develop the electrostatic latent image into a toner image; and

a transfer section configured to transfer the toner image from the image bearing member to a transfer target, wherein

the image bearing member is the electrophotographic photosensitive member according to claim 1 ,

the charger has a positive charging polarity, and

the transfer section transfers the toner image from the image bearing member to the transfer target while bringing the transfer target into contact with the surface of the image bearing member.

13. The image forming apparatus according to claim 12 , wherein

the transfer target is a recording medium.

14. The image forming apparatus according to claim 12 , wherein

the development section develops the electrostatic latent image into a toner image while in contact with the surface of the image bearing member.

15. The image forming apparatus according to claim 12 , wherein

the development section cleans the surface of the image bearing member.