JP7791735B2 - Electrophotographic photoreceptor, process cartridge, electrophotographic apparatus, and method for manufacturing electrophotographic photoreceptor - Google Patents

Description

This disclosure relates to an electrophotographic photoreceptor, a process cartridge and an electrophotographic apparatus having the electrophotographic photoreceptor, and a method for manufacturing the electrophotographic photoreceptor.

Electrophotographic photoreceptors containing organic photoconductive materials (charge-generating materials) are widely used in electrophotographic devices. In recent years, there has been a demand for improved mechanical durability (wear resistance) of electrophotographic photoreceptors in order to extend their lifespan and achieve higher image quality during repeated use.

One technique for improving the wear resistance of electrophotographic photoreceptors is to incorporate fluorine-containing resin particles into the surface layer of the electrophotographic photoreceptor, thereby reducing friction between the surface layer and a contact member such as a cleaning blade. Patent Document 1 discloses a technique for forming a surface layer using a dispersion of fluorine-containing resin particles, such as polytetrafluoroethylene resin particles, as a coating liquid for the surface layer.

Furthermore, when preparing a dispersion of fluorine-containing resin particles, a method is known in which a fluorine-containing (meth)acrylic polymer is used as a dispersant for the fluorine-containing resin particles in order to improve dispersibility. Patent Documents 2 and 3 disclose techniques for improving the dispersibility of fluorine-containing resin particles by using a fluorine-containing (meth)acrylic polymer with a specific structure as a dispersant.

Patent Document 4 discloses an electrophotographic photoreceptor having an outermost surface layer containing a fluorine-based graft polymer and fluorine-containing resin particles, in which the fluorine-based graft polymer contains structural units with acidic groups having a pKa of 3 or less.

Japanese Patent Application Publication No. 06-332219 JP 2012-189715 A JP 2009-104145 A Japanese Patent Application Laid-Open No. 2021-47236

However, while the techniques disclosed in Patent Documents 2 and 3 provide a surface layer with excellent dispersibility of fluorine-containing resin particles, they sometimes fail to sufficiently suppress potential fluctuations during repeated use of the electrophotographic photoreceptor. In particular, electrophotographic photoreceptors having a surface layer with excellent abrasion resistance, which is intended to extend the life of the electrophotographic photoreceptor, have the problem of large potential fluctuations during long-term repeated use. Therefore, there is room for improvement in suppressing potential fluctuations during repeated use of the electrophotographic photoreceptor.

One aspect of the present disclosure is to provide an electrophotographic photoreceptor in which potential fluctuations during repeated use are suppressed.
Another aspect of the present disclosure is directed to providing a process cartridge in which the electrophotographic photosensitive member is mounted, and an electrophotographic apparatus equipped with the process cartridge.
Another aspect of the present disclosure is directed to providing a method for producing the electrophotographic photoreceptor.

According to one aspect of the present disclosure, there is provided an electrophotographic photoreceptor having a surface layer, the surface layer containing fluorine atom-containing resin particles, a binder material, and a polymer A having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2) , wherein the polymer A does not have a structural unit having an acidic group having a pKa of 3 or less:
(In the above formula (1), R ¹¹ represents a hydrogen atom or a methyl group. R ¹² represents a single bond or a methylene group. Rf ¹ and Rf ² each independently represent a perfluoroalkylene group having 1 to 3 carbon atoms or a perfluoroalkylidene group having 1 to 3 carbon atoms. Rf ³ represents a perfluoroalkyl group having 1 to 3 carbon atoms.)
(In the above formula (2), Y ^represents an unsubstituted alkylene group; Y represents ^an unsubstituted alkylene group, an alkylene group substituted with a halogen atom, an alkylene group substituted with a hydroxy group, an ester bond (-COO-), an amide bond (-NHCO-), a urethane bond (-NHCOO-), or a divalent linking group derived by combining one or more selected from these groups and bonds with -O- or -S-, or a single bond; Z represents ^a structure represented by the following formula (2A) (Z represents an alkyl group having ¹ to 4 carbon atoms), a cyano group, or a phenyl group; R ^and R ^each independently represent a hydrogen atom or a methyl group; and m is an integer of 25 to 150.)
According to another aspect of the present disclosure, there is provided an electrophotographic photoreceptor having a surface layer, the surface layer containing fluorine atom-containing resin particles, a binder material, and a polymer A having a structural unit represented by the above formula (1), the content of the polymer A being 2% by mass or more and 10% by mass or less relative to the mass of the fluorine atom-containing resin particles in the surface layer, and the polymer A not having a structural unit having an acidic group with a pKa of 3 or less.
According to yet another aspect of the present invention, there is provided an electrophotographic photoreceptor having a surface layer, the surface layer comprising fluorine atom-containing resin particles, a binder material, and a polymer A having a structural unit represented by the above formula (1), wherein the content of the structural unit represented by the formula (1) in the polymer A is 5% by number or more and 95% by number or less based on the total structural units in the polymer A, and the polymer A does not have a structural unit having an acidic group having a pKa of 3 or less.

It is preferable that the surface layer does not contain a polymer having a structural unit with an acidic group having a pKa of 3 or less.

According to another aspect of the present disclosure, there is provided a process cartridge that integrally supports the electrophotographic photosensitive member and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, and is detachably attachable to the main body of an electrophotographic apparatus.
According to another aspect of the present disclosure, there is provided an electrophotographic apparatus having the electrophotographic photoreceptor, a charging unit, an exposure unit, a developing unit, and a transfer unit.
According to another aspect of the present disclosure, there is provided a method for producing the electrophotographic photoreceptor.

One aspect of the present disclosure provides an electrophotographic photoreceptor that has excellent dispersibility of fluorine-containing resin particles in the surface layer and suppresses potential fluctuations during repeated use.

FIG. 2 is a schematic diagram illustrating an example of the configuration of an electrophotographic photosensitive member. FIG. 1 is a diagram showing an example of a polishing machine using a polishing sheet. 1 is a diagram showing an example of a schematic configuration of a process cartridge in which an electrophotographic photosensitive member is mounted, and an electrophotographic apparatus including the process cartridge. FIG. 1 is a schematic view illustrating an example of a process cartridge having an electrophotographic photosensitive member. 1 is a schematic diagram illustrating an example of an electrophotographic apparatus having an electrophotographic photosensitive member.

As a result of investigations by the present inventors, it has been found that by incorporating fluorine atom-containing resin particles, a binder material, and a polymer A having a structural unit represented by the following formula (1) into the surface layer of an electrophotographic photoreceptor,
The surface layer has excellent dispersibility of fluorine-containing resin particles, and
It has been found that an electrophotographic photoreceptor can be obtained in which potential fluctuations during repeated use are suppressed.
(In formula (1), R ¹¹ represents a hydrogen atom or a methyl group. R ¹² represents a single bond or a methylene group. Rf ¹ and Rf ² each independently represent a perfluoroalkylene group having 1 to 3 carbon atoms or a perfluoroalkylidene group having 1 to 3 carbon atoms. Rf ³ represents a perfluoroalkyl group having 1 to 3 carbon atoms.)

The polymer A does not have a structural unit having an acidic group with a pKa of 3 or less.
The surface layer may or may not contain a polymer having a structural unit with an acidic group having a pKa of 3 or less, but it is preferable that the surface layer does not contain such a polymer.

The pKa of an acidic group can be determined by measurement using known methods such as titration. Examples of acidic groups with a pKa of 3 or less include sulfonic acid groups (methanesulfonic acid: -2.6), phosphonic acid groups (first dissociation: 1.5), phosphate groups (first dissociation: 2.12), and fluorinated alkylcarboxylic acid groups (e.g., trifluoroacetic acid: -0.25, difluoroacetic acid: 1.24, monofluoroacetic acid: 2.66).

The inventors believe that polymer A having the structural unit represented by formula (1) functions as a dispersant for fluorine-containing resin particles in the process of preparing a surface layer coating liquid for forming the surface layer of an electrophotographic photoreceptor.

The inventors speculate as follows about the reason why the electrophotographic photoreceptor of the present disclosure has excellent dispersibility of fluorine atom-containing resin particles in the surface layer and excellent suppression of potential fluctuations during repeated use.

An electrophotographic photoreceptor having a surface layer containing fluorine atom-containing resin particles and a dispersant tends to have large fluctuations in potential with repeated use. This is thought to be because charges tend to accumulate in the -(CF ₂ ) _n - chains of the dispersant attached to the fluorine atom-containing resin particles contained in the surface layer.

As a result of investigations by the present inventors, it was found that when a polymer having a structural unit containing a -(CF ₂ ) _n - chain is incorporated into a surface layer, the presence of an oxygen atom between the -(CF ₂ ) _n - chain and the -(CF ₂ ) _n - chain is effective in suppressing charge trapping. However, the greater the number of carbon atoms in the -(CF ₂ ) _n - chain, the more easily charge accumulates, and in some cases the effect of suppressing potential fluctuations cannot be fully achieved.

As a result of further investigations, the inventors have discovered that by incorporating polymer A having a structural unit represented by formula (1) into the surface layer, charge trapping is suppressed, and an electrophotographic photoreceptor can be obtained in which potential fluctuations during repeated use are suppressed.

In the formula (1), ^Rf1 and ^Rf2 are perfluoroalkylene groups having 1 to 3 carbon atoms or perfluoroalkylidene groups having 1 to 3 carbon atoms, and ^Rf3 is a perfluoroalkyl group having 1 to 3 carbon atoms. This is thought to prevent charge from accumulating in the structural unit represented by the formula (1). Furthermore, by making ^R12 in the formula (1) a single bond or a methylene group, the difference in surface energy between the structural unit represented by the formula (1) and the fluorine-containing resin particles is thought to be reduced, making it easier for the structural unit to adhere to the fluorine-containing resin particles.

<Fluorine atom-containing resin particles>
The surface layer of the electrophotographic photoreceptor of the present disclosure contains fluorine atom-containing resin particles. The content of the fluorine atom-containing resin particles in the surface layer is preferably 5% by mass or more and 40% by mass or less relative to the total mass of the surface layer.
Examples of resins contained in the fluorine atom-containing resin particles used in the present disclosure include polytetrafluoroethylene resin, polychlorotrifluoroethylene resin, polytetrafluoroethylenepropylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, and polydichlorodifluoroethylene resin. It is also preferable to use particles containing multiple types of the above resins. Among the above, from the viewpoint of improving dispersibility, it is more preferable that the fluorine atom-containing resin particles be polytetrafluoroethylene (PTFE) resin.

When observing the cross section of the surface layer, the fluorine atom-containing resin particles preferably have an arithmetic mean of the major axis of the primary particles (average primary particle size) measured from a secondary electron image taken with a scanning electron microscope of 150 nm or more and 300 nm or less, from the viewpoints of improving dispersibility and suppressing potential fluctuations. Furthermore, the fluorine atom-containing resin particles preferably have an average primary particle size of 180 nm or more and 250 nm or less.

It is preferable that the fluorine atom-containing resin particles have an average circularity (average circularity) of 0.75 or more, calculated from the area and perimeter of primary particles measured from secondary electron images taken with a scanning electron microscope.

To ensure that the average primary particle size and average circularity measurements of the fluorine atom-containing resin particles contained in the surface layer of the electrophotographic photoreceptor of the present disclosure fall within the above ranges, fluorine atom-containing resin particles can be used such that the average primary particle size and average circularity values calculated by the following methods fall within the above ranges.

(Method for measuring average primary particle size and average roundness)
That is, in the examples of the present disclosure, the average particle size and average circularity of the fluorine-containing resin particles contained in the surface layer of the electrophotographic photoreceptor were measured using a field emission scanning electron microscope (FE-SEM) as follows. The fluorine-containing resin particles were attached to commercially available carbon conductive tape, and the fluorine-containing resin particles not attached to the conductive tape were removed with compressed air, followed by platinum deposition. The deposited fluorine-containing resin particles were observed using an FE-SEM (S-4700) manufactured by Hitachi High-Technologies Corporation. The measurement conditions for the FE-SEM were as follows:
Acceleration voltage: 2 kV
WD: 5mm
Magnification: 20,000 times Number of pixels: 1280 pixels vertically, 960 pixels horizontally (size of one pixel: 5 nm)
From the obtained image, the Feret's diameters of 100 particles were determined using ImageJ (open source software manufactured by the National Institutes of Health (NIH)), and the average value was calculated to obtain the average particle size.
Similarly, the area and circumference were determined, and the circularity was calculated from the following formula (II), and the average value was calculated to obtain the average circularity.
Circularity = 4 × π × (area) ÷ (perimeter squared) Formula (II)

The fluorine atom-containing resin particles disclosed herein may be used alone or in combination of two or more types.

<Polymer A having a structural unit represented by formula (1)>
The surface layer of the electrophotographic photoreceptor of the present disclosure contains a polymer A having a structural unit represented by the following formula (1).

In the formula (1), R ¹¹ is a hydrogen atom or a methyl group. R ¹² is a single bond or a methylene group. When R ¹² is an alkylene group having 2 or more carbon atoms, the difference in surface energy between the structural unit represented by the formula (1) and the fluorine-containing resin particles becomes large, making it difficult for the structural unit to adhere to the fluorine-containing resin particles and resulting in insufficient dispersibility. Rf ¹ and Rf ² are each independently a perfluoroalkylene group having 1 to 3 carbon atoms or a perfluoroalkylidene group having 1 to 3 carbon atoms. Rf ³ is a perfluoroalkyl group having 1 to 3 carbon atoms. When Rf ¹ to Rf ³ each have 4 or more carbon atoms, charge accumulation in the structural unit represented by the formula (1) cannot be sufficiently suppressed, and potential fluctuations during repeated use of the electrophotographic photosensitive member cannot be sufficiently suppressed.

In addition, in the formula (1), the total number of carbon atoms of Rf ¹ to Rf ³ is preferably 6 or more and 9 or less from the viewpoint of improving the dispersibility of the fluorine atom-containing resin particles. Furthermore, from the viewpoint of suppressing potential fluctuations, the total number of carbon atoms of Rf ¹ to Rf ³ is more preferably 6 or more and 8 or less.

Examples of the structural unit represented by formula (1) contained in polymer A having the structural unit represented by formula (1) used in the present disclosure include the structures shown in Table 1 below.

From the viewpoint of improving the dispersibility of fluorine-containing resin particles, the content of the structural unit represented by formula (1) in polymer A contained in the surface layer of the electrophotographic photoreceptor of the present disclosure is preferably 5% by number or more and 95% by number or less (0.1% by mass or more and 80% by mass or less) of all structural units contained in polymer A. Furthermore, the content of the structural unit represented by formula (1) is more preferably 50% by number or more and 95% by number or less (1% by mass or more and 80% by mass or less) of all structural units contained in polymer A. Furthermore, the content of the structural unit represented by formula (1) is more preferably 70% by number or more and 90% by number or less (4% by mass or more and 66% by mass or less) of all structural units contained in polymer A.

The weight-average molecular weight of polymer A having the structural unit represented by formula (1) contained in the surface layer of the electrophotographic photoreceptor of the present disclosure is preferably 16,000 or more and 100,000 or less, from the viewpoints of improving the dispersibility of fluorine-containing resin particles and suppressing potential fluctuations. Furthermore, the weight-average molecular weight of polymer A having the structural unit represented by formula (1) is more preferably 18,000 or more and 80,000 or less.

The weight-average molecular weight of polymer A having the structural unit represented by formula (1) can be measured and calculated by the following method.

(Weight average molecular weight measurement by GPC)
The weight average molecular weight according to the present disclosure is measured by gel permeation chromatography (GPC) as follows.
First, a sample is dissolved in tetrahydrofuran (THF) at room temperature for 24 hours. The resulting solution is then filtered through a solvent-resistant membrane filter "Maesholidisc" (manufactured by Tosoh Corporation) with a pore size of 0.2 μm to obtain a sample solution. The sample solution is adjusted so that the concentration of components soluble in THF is approximately 0.8% by mass. This sample solution is used for measurements under the following conditions.
Apparatus: HLC8120 GPC (detector: RI) (manufactured by Tosoh Corporation)
Column: 7 columns of Shodex KF-801, 802, 803, 804, 805, 806, and 807 (manufactured by Showa Denko K.K.)
Eluent: tetrahydrofuran (THF)
・Flow rate: 1.0ml/min
Oven temperature: 40.0°C
Sample injection volume: 0.10 ml
In calculating the molecular weight of a sample, a molecular weight calibration curve prepared using standard polystyrene resins (for example, trade names "TSK Standard Polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500", manufactured by Tosoh Corporation) is used.

The content of polymer A having the structural unit represented by formula (1) relative to the fluorine atom-containing resin particles in the surface layer is preferably 2% by mass or more and 10% by mass or less, from the viewpoints of improving dispersibility and suppressing potential fluctuations. Furthermore, the content of polymer A having the structural unit represented by formula (1) relative to the fluorine atom-containing resin particles in the surface layer is more preferably 4% by mass or more and 8% by mass or less, from the viewpoints of improving dispersibility and suppressing potential fluctuations.

The polymer A is preferably a polymer having a structural unit represented by the formula (1) and a structural unit represented by the following formula (2).
(In formula (2),
Y ^A1 represents an unsubstituted alkylene group;
^YB represents an unsubstituted alkylene group, an alkylene group substituted with a halogen atom, an alkylene group substituted with a hydroxy group, an ester bond (—COO—), an amide bond (—NHCO—), a urethane bond (—NHCOO—), or a divalent linking group derived by combining one or more of these groups or bonds with —O— or —S—, or a single bond;
Z ^A represents a structure represented by formula (2A), a cyano group, or a phenyl group;
R ²¹ and R ²² each independently represent a hydrogen atom or a methyl group;
m is an integer of 25 or more and 150 or less.
(In formula (2A), ^Z represents an alkyl group having 1 to 4 carbon atoms.)

In formula (2), when Y ^B represents an ester bond, -Y ^A1 -Y ^B -CH ₂ - may be either -Y ^A1 -CO-O-CH ₂ - or -Y ^A1 -O-CO-CH ₂ -, and is preferably -Y ^A1 -CO-O-CH ₂ -. In addition, in formula (2), when Y ^B represents an amide bond, -Y ^A1 -Y ^B -CH ₂ - may be either -Y ^A1 -NH-CO-CH ₂ - or -Y ^A1 -CO-NH-CH ₂ -, and is preferably -Y ^A1 -NH-CO-CH ₂ -. In addition, in formula (2), when Y ^B is a urethane bond, -Y ^A1 -Y ^B -CH ₂ - may be either -Y ^A1 -NH-CO-O-CH ₂ - or -Y ^A1 -O-CO-NH-CH ₂ -, and is preferably -Y ^A1 -NH-CO-O-CH ₂ -.

In addition, -Y ^A1 -Y ^B - in the formula (2) preferably has a structure represented by -Y ^A1 -(Y ^A2 ) _b -(Y ^A3 ) _c -(Y ^A4 ) _d -(Y ^A5 ) _e -(Y ^A6 ) _f -.
(Y ^A1 represents an unsubstituted alkylene group,
Y ^A2 represents a methylene group substituted with at least one atom selected from the group consisting of a hydroxy group and a halogen atom;
Y ^A3 represents an unsubstituted alkylene group;
Y ^A4 represents an ester bond, an amide bond or a urethane bond;
Y ^A5 represents an unsubstituted alkylene group;
Y ^A6 represents an oxygen atom or a sulfur atom;
b, c, d, e and f each independently represent 0 or 1.

It is preferable that the polymer A has only the structural unit represented by formula (1) and the structural unit represented by formula (2) as structural units.

In the formula (2),
is preferably not an acidic group having a pKa of 3 or less.

In the formula (2),
is preferably not —SO ₃ H.

In polymer A having the structural unit represented by formula (1) and the structural unit represented by formula (2), the molar ratio of the structural unit represented by formula (1) to the structural unit represented by formula (2) is preferably 1:19 to 19:1, more preferably 1:1 to 19:1, and even more preferably 7:3 to 9:1.

Examples of the structural unit represented by the formula (2) include those having the structures shown in Table 2 below.

<Electrophotographic Photoreceptor>
An example of the layer structure of the electrophotographic photoreceptor of the present disclosure is shown in Figure 1. In Figure 1, an undercoat layer 102, a charge generation layer 103, a charge transport layer 104, and a surface layer 105 are laminated on a support 101. The photosensitive layer may be a laminated type photosensitive layer having a charge generation layer and a charge transport layer, or may be a single-layer type photosensitive layer containing a charge generation material and a charge transport material.

The surface layer of the electrophotographic photoreceptor of the present disclosure contains fluorine atom-containing resin particles and polymer A having a structural unit represented by formula (1) above.

A method for manufacturing the electrophotographic photoreceptor of the present disclosure includes preparing a coating liquid for each layer described below, applying the desired layers in order, and drying. In this case, methods for applying the coating liquid include dip coating, spray coating, inkjet coating, roll coating, die coating, blade coating, curtain coating, wire bar coating, and ring coating. Among these, dip coating is preferred from the standpoints of efficiency and productivity.

The configuration of the electrophotographic photoreceptor of the present disclosure will be described below.
<Support>
The support of the electrophotographic photoreceptor is preferably conductive (conductive support). The support may be cylindrical, belt-like, or sheet-like. Of these, a cylindrical support is preferred. The surface of the support may be subjected to electrochemical treatment such as anodizing, blasting, cutting, or the like.
The support is preferably made of a metal, a resin, or a glass.
Examples of metals include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof. Among these, an aluminum support using aluminum is preferred.
It is also preferable to impart electrical conductivity to the resin or glass by processing such as mixing or coating with an electrically conductive material.

<Conductive layer>
A conductive layer may be provided on the support, which can conceal scratches and irregularities on the surface of the support and control light reflection on the surface of the support.
The conductive layer preferably contains conductive particles and a resin.

Examples of materials for the conductive particles include metal oxides, metals, and carbon black.
Examples of metal oxides include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, strontium titanate, magnesium oxide, antimony oxide, bismuth oxide, etc. Examples of metals include aluminum, nickel, iron, nichrome, copper, zinc, silver, etc.
Among these, it is preferable to use metal oxide particles as the conductive particles, and it is particularly preferable to use titanium oxide particles, tin oxide particles, or zinc oxide particles.
When metal oxide particles are used as the conductive particles, the surfaces of the metal oxide particles may be treated with a silane coupling agent or the like, or the metal oxide particles may be doped with an element such as phosphorus or aluminum or an oxide thereof.
The conductive particles may have a laminated structure including a core particle and a coating layer covering the core particle. Examples of the core particle include titanium oxide particles, barium sulfate particles, and zinc oxide particles. Examples of the coating layer include metal oxide particles such as tin oxide.
When metal oxide particles are used as the conductive particles, the volume average particle size thereof is preferably 1 nm or more and 500 nm or less, and more preferably 3 nm or more and 400 nm or less.

Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, and alkyd resin.
The conductive layer may further contain silicone oil, resin particles, a masking agent such as titanium oxide, and the like.

The conductive layer can be formed by preparing a conductive layer coating solution containing the above materials and solvent, forming this coating film on a support, and drying it. Examples of solvents used in the conductive layer coating solution include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Methods for dispersing conductive particles in the conductive layer coating solution include methods using a paint shaker, sand mill, ball mill, or liquid collision-type high-speed disperser.

The thickness of the conductive layer is preferably 1 μm or more and 50 μm or less, and particularly preferably 3 μm or more and 40 μm or less.

<Undercoat layer>
In the present disclosure, an undercoat layer may be provided on the support or the conductive layer. By providing an undercoat layer, adhesion between layers can be improved and a charge injection blocking function can be imparted.

The undercoat layer preferably contains a resin. Alternatively, the undercoat layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group.
Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinylphenol resin, alkyd resin, polyvinyl alcohol resin, polyethylene oxide resin, polypropylene oxide resin, polyamide resin, polyamic acid resin, polyimide resin, polyamideimide resin, and cellulose resin.
Examples of the polymerizable functional group contained in the monomer having a polymerizable functional group include an isocyanate group, a blocked isocyanate group, a methylol group, an alkylated methylol group, an epoxy group, a metal alkoxide group, a hydroxy group, an amino group, a carboxy group, a thiol group, a carboxylic acid anhydride group, and a carbon-carbon double bond group.

Furthermore, for the purpose of improving electrical properties, the undercoat layer may further contain an electron transport material, metal oxide particles, metal particles, a conductive polymer, etc. Among these, it is preferable to use an electron transport material or metal oxide particles.
Examples of the electron transport substance include a quinone compound, an imide compound, a benzimidazole compound, a cyclopentadienylidene compound, a fluorenone compound, a xanthone compound, a benzophenone compound, a cyanovinyl compound, an aryl halide compound, a silole compound, a boron-containing compound, etc. An electron transport substance having a polymerizable functional group may be used as the electron transport substance, and the undercoat layer may be formed as a cured film by copolymerizing the electron transport substance with the above-mentioned monomer having the polymerizable functional group.
Examples of metal oxide particles include particles of indium tin oxide, tin oxide, indium oxide, titanium oxide, strontium titanate, zinc oxide, and aluminum oxide. Silicon dioxide particles can also be used. Examples of metal particles include particles of gold, silver, and aluminum.
The metal oxide particles contained in the undercoat layer may be surface-treated with a surface treatment agent such as a silane coupling agent.

The surface treatment of the metal oxide particles can be carried out by a common method, such as a dry method or a wet method.
In the dry method, metal oxide particles are stirred in a mixer capable of high-speed stirring, such as a Henschel mixer, and an alcohol aqueous solution, organic solvent solution, or aqueous solution containing a surface treatment agent is added to the metal oxide particles to uniformly disperse them, followed by drying.
In the wet method, metal oxide particles and a surface treatment agent are stirred in a solvent or dispersed in a sand mill using glass beads or the like, and after dispersion, the solvent is removed by filtration or vacuum distillation. After solvent removal, it is preferable to further bake the mixture at 100°C or higher.

The undercoat layer may further contain additives, such as known materials such as metal particles such as aluminum particles, conductive material particles such as carbon black, charge transport materials, metal chelate compounds, and organometallic compounds.

The undercoat layer can be formed by preparing a coating solution for the undercoat layer containing the above-mentioned materials and solvent, forming this coating film on the support or conductive layer, and then drying and/or curing it.

Solvents used in the coating solution for the undercoat layer include organic solvents such as alcohols, sulfoxides, ketones, ethers, esters, aliphatic halogenated hydrocarbons, and aromatic compounds. In the present disclosure, it is preferable to use alcohol-based and ketone-based solvents.

Dispersion methods for preparing the coating solution for the undercoat layer include methods using a homogenizer, ultrasonic disperser, ball mill, sand mill, roll mill, vibration mill, attritor, or liquid collision-type high-speed disperser.

The thickness of the undercoat layer is preferably 0.1 μm or more, more preferably 0.2 μm or more, and particularly preferably 0.3 μm or more. Furthermore, the thickness of the undercoat layer is preferably 50 μm or less, more preferably 40 μm or less, more preferably 30 μm or less, more preferably 10 μm or less, and particularly preferably 5 μm or less.

<Photosensitive layer>
Photosensitive layers of electrophotographic photoreceptors are mainly classified into (1) multi-layer photosensitive layers and (2) single-layer photosensitive layers. (1) Multi-layer photosensitive layers are photosensitive layers having a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. (2) Single-layer photosensitive layers are photosensitive layers containing both a charge generation material and a charge transport material.

(1) Multilayer Photosensitive Layer The multilayer photosensitive layer has a charge generating layer and a charge transport layer.

(1-1) Charge Generation Layer The charge generation layer preferably contains a charge generation substance and a resin.

Examples of charge-generating materials include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, and phthalocyanine pigments. Among these, azo pigments and phthalocyanine pigments are preferred. Among phthalocyanine pigments, oxytitanium phthalocyanine pigments, chlorogallium phthalocyanine pigments, and hydroxygallium phthalocyanine pigments are preferred.
The content of the charge generating material in the charge generating layer is preferably 40% by weight to 85% by weight, and more preferably 60% by weight to 80% by weight, based on the total weight of the charge generating layer.

Examples of resins include polyester resin, polycarbonate resin, polyvinyl acetal resin, polyvinyl butyral resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenolic resin, polyvinyl alcohol resin, cellulose resin, polystyrene resin, polyvinyl acetate resin, and polyvinyl chloride resin. Of these, polyvinyl butyral resin is more preferred.

The charge generating layer may also contain additives such as antioxidants and ultraviolet absorbers. Specific examples include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, and benzophenone compounds.

The charge generation layer can be formed by preparing a coating solution for the charge generation layer containing the above materials and solvent, forming this coating film on the undercoat layer, and drying it. Examples of solvents that can be used in the coating solution include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

The thickness of the charge generating layer is preferably 0.1 μm or more and 1 μm or less, and more preferably 0.15 μm or more and 0.4 μm or less.

(1-2) Charge Transport Layer The charge transport layer preferably contains a charge transport material and a binder material.
When a protective layer (described later) is not provided, the charge transport layer serves as the surface layer of the electrophotographic photoreceptor. In this case, the charge transport layer contains fluorine atom-containing resin particles, a binder material, and a polymer A having a structural unit represented by the formula (1).

Examples of the charge transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, triarylamine compounds, and resins having groups derived from these materials. Among these, triarylamine compounds are preferred.
The content of the charge transport material in the charge transport layer is preferably from 25% by weight to 70% by weight, and more preferably from 30% by weight to 55% by weight, based on the total weight of the charge transport layer.

As the binding material, a thermoplastic resin (hereinafter also referred to as "resin") is used.
Examples of thermoplastic resins include polyester resins, polycarbonate resins, acrylic resins, and polystyrene resins. Among these, polycarbonate resins and polyester resins are preferred. As the polyester resin, polyarylate resins are particularly preferred.
The content ratio (mass ratio) of the charge transport material to the resin is preferably 4:10 to 20:10, and more preferably 5:10 to 12:10.

The content of fluorine atom-containing resin particles in the charge transport layer is preferably 5% by weight or more and 15% by weight or less. Furthermore, the content of fluorine atom-containing resin particles in the charge transport layer is preferably 7% by weight or more and 10% by weight or less.

The charge transport layer may also contain additives such as antioxidants, UV absorbers, plasticizers, and leveling agents. Specific examples include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, polystyrene resin particles, polyethylene resin particles, and boron nitride particles.

The charge transport layer can be formed by preparing a coating solution for the charge transport layer containing the above materials and solvent, forming this coating film on the charge generation layer, and drying it. Examples of solvents used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Of these solvents, ether-based solvents and aromatic hydrocarbon-based solvents are preferred.

The thickness of the charge transport layer is preferably 5 μm or more and 50 μm or less, more preferably 8 μm or more and 40 μm or less, and particularly preferably 10 μm or more and 30 μm or less.

(2) Single-Layer Photosensitive Layer The single-layer photosensitive layer can be formed by preparing a coating solution for the photosensitive layer containing a charge generating material, a charge transport material, a resin, and a solvent, forming the coating film on the undercoat layer, and drying it. The charge generating material, charge transport material, and resin are the same as those exemplified in "(1) Multilayer Photosensitive Layer" above.

<Protective layer>
In the present disclosure, a protective layer may be provided on the photosensitive layer, which can improve durability.

When a protective layer is provided, the protective layer becomes the surface layer of the electrophotographic photoreceptor. In this case, the protective layer contains fluorine atom-containing resin particles, a binder material, and polymer A having a structural unit represented by formula (1) above.

The protective layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group, which is a raw material for the binder material. Examples of the reaction include thermal polymerization, photopolymerization, and radiation-induced polymerization. Examples of the polymerizable functional group possessed by the monomer having a polymerizable functional group include an isocyanate group, a blocked isocyanate group, a methylol group, an alkylmethylol group, an epoxy group, a metal alkoxyl group, a hydroxyl group, an amino group, a carboxyl group, a thiol group, a carboxylic acid anhydride group, and a group containing a carbon-carbon double bond. Examples of the group containing a carbon-carbon double bond include an acryloyl group and a methacryloyl group. A monomer having charge transport capability may also be used as the monomer having a polymerizable functional group.

Here, the cured product of the monomer having a polymerizable functional group is the binder material of the protective layer.
As the monomer having a polymerizable functional group, it is preferable to use a hole transporting compound having a chain-polymerizable functional group.

The hole transporting compound having a chain-polymerizable functional group is more preferably a compound represented by the following formula (CT-1) or (CT-2).
(In the formula (CT-1), Ar ¹¹ to Ar ¹³ each independently represent a substituted aryl group or an unsubstituted aryl group. The substituent that the substituted aryl group may have is an alkyl group having 1 to 6 carbon atoms, or a monovalent functional group represented by any one of the following formulae (P-1) to (P-3). However, the compound represented by the formula (CT-1) has at least one monovalent functional group represented by any one of the following formulae (P-1) to (P-3).)
(In the formula (CT-2), Ar ²¹ to Ar ²⁴ are each independently a substituted aryl group or an unsubstituted aryl group, and Ar ²⁵ is a substituted arylene group or an unsubstituted arylene group. The substituent that the substituted aryl group may have is an alkyl group having 1 to 6 carbon atoms, or a monovalent functional group represented by the following formulas (P-1) to (P-3). The substituent that the substituted arylene group may have is an alkyl group having 1 to 6 carbon atoms, or a monovalent functional group represented by the following formulas (P-1) to (P-3). However, the compound represented by the formula (CT-2) has at least one monovalent functional group represented by any of the following formulas (P-1) to (P-3).)
(In the formula (P-1), Z ¹¹ is a single bond or an alkylene group having 1 to 6 carbon atoms, and X ¹¹ is a hydrogen atom or a methyl group.)
(In the formula (P-2), ^Z21 is a single bond or an alkylene group having 1 to 6 carbon atoms.)
(In the formula (P-3), Z ³¹ is a single bond or an alkylene group having 1 to 6 carbon atoms.)

The content of fluorine-containing resin particles in the protective layer is preferably 20% by mass or more and 40% by mass or less. Furthermore, the content of fluorine-containing resin particles in the protective layer is preferably 25% by mass or more and 35% by mass or less.

The protective layer preferably contains a compound represented by the following formula (3): In addition, when preparing a coating liquid for the surface layer, the compound represented by the following formula (3) is preferably a liquid compound from the viewpoint of being used as a dispersion medium.
In the formula (3), R ³¹ is an alkyl group or a fluoroalkyl group, R ³² is a fluoroalkyl group, and R ³¹ is preferably a fluoroalkyl group.

Examples of compounds represented by formula (3) include methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether, 1,1,1,2,3,4,4,5,5,5-decafluoro-3-methoxy-2-(trifluoromethyl)pentane 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether, and the like. Among these, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether is preferred from the viewpoints of improving dispersibility and suppressing potential fluctuations.

From the viewpoint of suppressing potential fluctuations, the content of the compound represented by formula (3) in the protective layer is preferably 1 ppm or more and 10 ppm or less. Furthermore, it is more preferable that the compound represented by formula (3) is 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether.

Methods for measuring the content of the compound represented by formula (3) in the protective layer include, for example, GCMS analysis. A measurement sample is prepared by scraping off the surface layer on the electrophotographic photoreceptor with a razor or similar tool, and the film mass is used. By analyzing this measurement sample with GCMS, the content of the compound represented by formula (3) contained in the surface layer can be measured. An example of an apparatus that can be used for GCMS analysis is the GCMS-QP2000 (manufactured by Shimadzu Corporation). In the examples of the present disclosure, after obtaining a measurement sample using the above-described method, the content of the compound represented by formula (3) was measured using the above-described GCMS apparatus.

The protective layer may contain additives such as antioxidants, UV absorbers, plasticizers, and leveling agents. Specific examples include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, and silicone oils.

The protective layer can be formed by preparing a protective layer coating solution containing the above materials and solvent, forming this coating film on the photosensitive layer, and then drying and/or curing it. Examples of solvents that can be used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, sulfoxide-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

The thickness of the protective layer is preferably 0.5 μm or more and 10 μm or less, and more preferably 1 μm or more and 7 μm or less.

<Surface treatment of electrophotographic photoreceptor>
In the present disclosure, the surface of the electrophotographic photosensitive member may be subjected to surface treatment. By performing the surface treatment, the behavior of a cleaning means (cleaning blade) that comes into contact with the electrophotographic photosensitive member can be further stabilized. Examples of surface treatment methods include a method in which a mold having convex portions is pressed against the surface of the electrophotographic photosensitive member to transfer the shape, a method in which an uneven shape is imparted by mechanical polishing, or a method in which powder is collided with the surface of the electrophotographic photosensitive member to roughen the surface. In this way, by providing concave or convex portions on the surface layer of the electrophotographic photosensitive member, the behavior of a cleaning means that comes into contact with the electrophotographic photosensitive member can be further stabilized.

The recesses or protrusions may be formed over the entire surface of the electrophotographic photoreceptor, or may be formed only on a portion of the surface of the electrophotographic photoreceptor. If the recesses or protrusions are formed only on a portion of the surface of the electrophotographic photoreceptor, it is preferable that the recesses or protrusions are formed over at least the entire area of contact with the cleaning means (cleaning blade).

When forming recesses, a mold with protrusions corresponding to the recesses is pressed against the surface of the electrophotographic photosensitive member to transfer the shape, thereby forming the recesses on the surface of the electrophotographic photosensitive member.

<Polishing tool used for mechanical polishing>
Mechanical polishing can be performed by known means. Generally, an abrasive tool is brought into contact with an electrophotographic photosensitive member, and one or both of them are moved relatively to polish the surface of the electrophotographic photosensitive member. The abrasive tool is a polishing member having a substrate and a layer in which abrasive grains are dispersed in a binder resin.

Examples of abrasive grains include particles of aluminum oxide, chromium oxide, diamond, iron oxide, cerium oxide, corundum, silica, silicon nitride, boron nitride, molybdenum carbide, silicon carbide, tungsten carbide, titanium carbide, and silicon oxide. The particle size of the abrasive grains is preferably 0.01 to 50 μm, and more preferably 1 to 15 μm. If the particle size of the abrasive grains is too small, the polishing power will be weak and it will be difficult to increase the F/C ratio on the outermost surface of the electrophotographic photoreceptor. These abrasive grains can be used alone or in combination of two or more types. When two or more types are mixed, the materials and particle sizes may be different or the same.

The binder resin used to disperse the abrasive grains in the polishing tool can be any of the well-known thermoplastic resins, thermosetting resins, reactive resins, electron beam curable resins, ultraviolet curable resins, visible light curable resins, and antifungal resins. Examples of thermoplastic resins include vinyl chloride resin, polyamide resin, polyester resin, polycarbonate resin, amino resin, styrene-butadiene copolymer, urethane elastomer, and polyamide-silicone resin. Examples of thermosetting resins include phenolic resin, phenoxy resin, epoxy resin, polyurethane resin, polyester resin, silicone resin, melamine resin, and alkyd resin. An isocyanate-based curing agent may also be added to the thermoplastic resin.

The thickness of the layer of the abrasive tool, which has abrasive grains dispersed in the binder resin, is preferably 1 to 100 μm. If the layer is too thick, unevenness in the thickness is likely to occur, resulting in uneven surface roughness on the object being polished. On the other hand, if the layer is too thin, the abrasive grains are more likely to fall off.

The shape of the substrate of the abrasive tool is not particularly limited. In the examples of the present disclosure, a sheet-like substrate is used to efficiently abrade a cylindrical electrophotographic photoreceptor, but other shapes are also possible. (Hereinafter, the abrasive tool of the present disclosure will also be referred to as an abrasive sheet.) The material of the substrate of the abrasive tool is also not particularly limited. For example, examples of materials for the sheet-like substrate include paper, woven fabric, nonwoven fabric, and plastic film.

The abrasive tool can be obtained by applying a coating material made by mixing and dispersing the above-mentioned abrasive grains, binder resin, and a solvent capable of dissolving the binder resin onto a substrate and drying it.

<Polishing equipment>
An example of the polishing device for the electrophotographic photosensitive member of the present disclosure is shown in FIG.
FIG. 2 shows an apparatus for polishing a cylindrical electrophotographic photoreceptor using an abrasive sheet. In FIG. 2, an abrasive sheet 2-1 is wound around a hollow shaft 2-6, and a motor (not shown) is disposed to apply tension to the abrasive sheet 2-1 in the direction opposite to the direction in which the abrasive sheet 2-1 is fed around the shaft 2-6. The abrasive sheet 2-1 is fed in the direction indicated by the arrow, passing through guide rollers 2-2a and 2-2b and a backup roller 2-3. After polishing, the abrasive sheet 2-1 is wound around a winding means 2-5 by a motor (not shown) via guide rollers 2-2c and 2-2d. Polishing is performed by constantly pressing the abrasive sheet 2-1 against the workpiece (electrophotographic photoreceptor before polishing) 2-4. Because the abrasive sheet 2-1 is often insulating, it is preferable to use a grounded or conductive material for the area in contact with the abrasive sheet 2-1.

The feed speed of the abrasive sheet 2-1 is preferably in the range of 10 to 1000 mm/min. If the feed rate is too low, the binder resin may adhere to the surface of the abrasive sheet 2-1, which may cause deep scratches on the surface of the workpiece 2-4.

The workpiece 2-4 is placed opposite the backup roller 2-3 via the abrasive sheet 2-1. The backup roller 2-3 is preferably made of an elastic material, in order to improve the uniformity of the surface roughness of the workpiece 2-4. At this time, the workpiece 2-4 and the backup roller 2-3 are pressed against each other via the abrasive sheet 2-1 at a desired setting value for a predetermined time, and the surface of the workpiece 2-4 is polished. The rotation direction of the workpiece 2-4 may be the same as or opposite to the feed direction of the abrasive sheet 2-1. The rotation direction may also be changed during polishing.

The pressure of the backup roller 2-3 against the object 2-4 to be processed depends on the hardness of the backup roller 2-3 and the polishing time, but is preferably 0.005 to 15 N/m ² .

The surface roughness of the electrophotographic photoreceptor can be adjusted by appropriately selecting the feed speed of the abrasive sheet 2-1, the pressing pressure of the backup roller 2-3, the type of abrasive grains in the abrasive sheet, the film thickness of the binder resin in the abrasive sheet, the thickness of the substrate, etc.

<Measurement of maximum height Rmax according to JIS B0601 1982>
The surface roughness of the electrophotographic photosensitive member can be measured by known means, for example, the following.
Surface roughness meters such as the Surfcorder SE3500 surface roughness measuring instrument manufactured by Kosaka Laboratory Co., Ltd. The Micromap 557N non-contact 3D surface measuring instrument manufactured by Ryoka Systems Co., Ltd. Microscopes capable of obtaining 3D shapes such as the VK-8550 and VK-9000 ultra-deep shape measuring microscopes manufactured by Keyence Corporation.

In this disclosure, the maximum height Rmax specified by the Japanese Industrial Standards (JIS) B0601 1982, which is an index of surface roughness, is used as the polishing depth L (μm). Furthermore, in this disclosure, Rmax is measured in advance within a 5 mm square piece of an electrophotographic photoreceptor cut out as a specimen for X-ray photoelectron spectroscopy, which will be described later. Measurements are performed at three random locations within the 5 mm square area, and the average value is used as the polishing depth L (μm).

<Process cartridge, electrophotographic apparatus>
The electrophotographic photosensitive member of the present disclosure may be one of the components of a process cartridge or an electrophotographic apparatus. The process cartridge is characterized by integrally supporting the electrophotographic photosensitive member described above and at least one means selected from the group consisting of a charging means, a developing means, a transfer means, and a cleaning means, and is detachably mountable to the main body of the electrophotographic apparatus. The electrophotographic apparatus is characterized by having the electrophotographic photosensitive member, a charging means, an exposure means, a developing means, and a transfer means described above.

Figure 3 shows an example of the schematic configuration of an electrophotographic device having a process cartridge equipped with an electrophotographic photosensitive member.

The cylindrical (drum-shaped) electrophotographic photoreceptor 201 rotates around its axis 202 in the direction indicated by the arrow at a predetermined peripheral speed (process speed). During rotation, the surface of the electrophotographic photoreceptor 201 is charged to a predetermined positive or negative potential by a charging device 203. While Figure 3 shows a roller charging method using a roller-type charging member, other charging methods, such as corona charging, proximity charging, and injection charging, may also be used. Exposure light 204 from an exposure device (not shown) is irradiated onto the charged surface of the electrophotographic photoreceptor 201, forming an electrostatic latent image corresponding to the desired image information. The exposure light 204 is intensity-modulated in response to a time-series electrical digital image signal representing the desired image information, and is output from an image exposure device such as a slit exposure or laser beam scanning exposure device. The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 201 is developed (normally or reversely) with toner contained in a developing device 205, forming a toner image on the surface of the electrophotographic photoreceptor 201. The toner image formed on the surface of the electrophotographic photosensitive member 201 is transferred to a transfer material 207 by a transfer unit 206. At this time, a bias voltage of a polarity opposite to that of the charge held by the toner is applied to the transfer unit 206 from a bias power supply (not shown). When the transfer material 207 is paper, the transfer material 207 is taken out from a paper feed unit (not shown) and fed between the electrophotographic photosensitive member 201 and the transfer unit 206 in synchronization with the rotation of the electrophotographic photosensitive member 201. The transfer material 207 onto which the toner image has been transferred from the electrophotographic photosensitive member 201 is separated from the surface of the electrophotographic photosensitive member 201 and transported to a fixing unit 208, where the toner image is fixed, and the transferred material is printed out of the electrophotographic apparatus as an image-formed product (print, copy). The electrophotographic apparatus may also have a cleaning unit 209 for removing deposits such as toner remaining on the surface of the electrophotographic photosensitive member 201 after transfer. Alternatively, a so-called cleanerless system may be used in which the deposits are removed by the developing unit or the like without providing a separate cleaning unit. A process cartridge can be formed by housing a plurality of components selected from the electrophotographic photosensitive member 201, the charging unit 203, the developing unit 205, and the cleaning unit 209 in a container and supporting them together. This can also be configured to be detachable from the main body of the electrophotographic apparatus. For example, the cartridge can be configured as follows: At least one selected from the charging unit 203, the developing unit 205, and the cleaning unit 209 is supported together with the electrophotographic photosensitive member 201 to form a cartridge. This can be made into a process cartridge 211 detachable from the main body of the electrophotographic apparatus using guide units 212, such as rails, of the main body of the electrophotographic apparatus. The electrophotographic apparatus may have a charge-eliminating mechanism that performs a charge-eliminating process on the surface of the electrophotographic photosensitive member 201 using pre-exposure light 210 from a pre-exposure unit (not shown). Guide units 212, such as rails, may be provided for attaching and detaching the process cartridge 11 to and from the main body of the electrophotographic apparatus. The electrophotographic apparatus of the present disclosure is characterized by having an electrophotographic photoreceptor 201, a charging unit 203, an exposure unit, a developing unit 205, and a transfer unit 206.

Furthermore, Figure 4 shows the configuration of a process cartridge equipped with the electrophotographic photosensitive member of the present disclosure, and Figure 5 shows an example of the schematic configuration of an electrophotographic device equipped with the process cartridge of Figure 4.

In Figure 4, a cylindrical electrophotographic photoreceptor 1 is rotated in the direction of the arrow at a predetermined peripheral speed. The peripheral surface of the rotated electrophotographic photoreceptor 1 is uniformly charged to a predetermined positive or negative potential by charging means 2. The charged peripheral surface of electrophotographic photoreceptor 1 is then exposed to exposure light (image exposure light) 3 output from exposure means (not shown), such as slit exposure or laser beam scanning exposure. In this way, an electrostatic latent image corresponding to the desired image is sequentially formed on the peripheral surface of electrophotographic photoreceptor 1. The voltage applied to charging means (such as a charging roller) 2 may be a voltage in which an AC component is superimposed on a DC component, or a voltage consisting solely of a DC component.

The electrostatic latent image formed on the peripheral surface of the electrophotographic photoreceptor 1 is developed into a toner image using toner contained in the developer of the developing means 4. Next, the toner image formed and carried on the peripheral surface of the electrophotographic photoreceptor 1 is sequentially transferred to a transfer material (paper, intermediate transfer material, etc.) 6 by a transfer bias from a transfer means (transfer roller, etc.) 5. The transfer material 6 is fed in synchronization with the rotation of the electrophotographic photoreceptor 1.

After the toner image is transferred, the surface of the electrophotographic photoreceptor 1 is neutralized by pre-exposure light 7 from a pre-exposure means (not shown), and then the surface is cleaned by cleaning means 8 to remove any residual toner. The electrophotographic photoreceptor 1 can then be used repeatedly for image formation. The pre-exposure means may be placed before or after the cleaning process, and is not necessarily required.

The electrophotographic photoreceptor 1 may be mounted in an electrophotographic device such as a copying machine or a laser beam printer. Alternatively, a process cartridge 9 may be configured in which a plurality of components, such as the electrophotographic photoreceptor 1, charging means 2, developing means 4, and cleaning means 8, are housed in a container and supported together, and configured to be detachable from the main body of the electrophotographic device. In Figure 4, the electrophotographic photoreceptor 1, charging means 2, developing means 4, and cleaning means 8 are supported together to form a process cartridge 9 that is detachable from the main body of the electrophotographic device.

Next, an electrophotographic apparatus equipped with the electrophotographic photoreceptor of the present disclosure will be described.
An example of the configuration of the electrophotographic apparatus of the present disclosure is shown in Figure 5. A yellow process cartridge 17, a magenta process cartridge 18, a cyan process cartridge 19, and a black process cartridge 20 corresponding to the respective colors, yellow, magenta, cyan, and black, are arranged side by side along the intermediate transfer body 10. The diameter, constituent materials, developer, charging method, and other means of the electrophotographic photosensitive member do not necessarily need to be uniform for each color.

When the image formation operation begins, toner images of each color are sequentially superimposed on the intermediate transfer body 10 according to the image formation process described above. In parallel, transfer paper 11 is fed from paper feed tray 13 via paper feed path 12 and fed to secondary transfer means 14 in synchronization with the rotation of the intermediate transfer body. The toner image on the intermediate transfer body 10 is transferred to the transfer paper 11 by a transfer bias from secondary transfer means 14. The toner image transferred onto the transfer paper 11 is transported along paper feed path 12, fixed onto the transfer paper by fixing means 15, and then discharged from paper discharge section 16.

The electrophotographic photoreceptor of the present disclosure can be used in laser beam printers, LED printers, copiers, facsimiles, and multifunction devices thereof.

The present disclosure will be explained in more detail below using examples and comparative examples, but is not limited to these. In the following description of the examples, "parts" are by mass unless otherwise specified.

<Synthesis of polymer A having a structural unit represented by formula (1)>
Polymer A (hereinafter also referred to as "graft copolymer") having a structural unit represented by formula (1) in the present disclosure was synthesized as follows. The acrylate compound and macromonomer compound used in the synthesis examples below can be produced by referring to, for example, JP-A-2009-104145.

(Graft Copolymer 1)
50 parts of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanoyl)acrylate (Sigma-Aldrich), 75 parts of the macromonomer represented by the following formula (A) (number average molecular weight 6,000), 0.437 parts of 1,1'-azobis(1-acetoxy-1-phenylethane) (trade name: OTAZO-15, Otsuka Chemical Co., Ltd.), and 338 parts of n-butyl acetate were mixed in a glass flask equipped with a stirrer, reflux condenser, nitrogen gas inlet tube, thermostatic bath, and thermometer at 20 ° C. under a nitrogen atmosphere for 30 minutes, and then the reaction mixture was heated to 85-90 ° C. and reacted for 5 hours. The reaction was stopped by cooling with ice, and a precipitate was obtained by adding 1500 parts of 2-propanol. This precipitate was washed with a mixed solvent of n-butyl acetate:2-propanol=1:5 and dried at a temperature of 80° C. under reduced pressure of 1325 Pa or less for 3 hours, thereby obtaining graft copolymer 1.

(Graft Copolymer 2)
Graft copolymer 2 was obtained in the same manner as for graft copolymer 1, except that 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanoyl)acrylate was changed to 1H,1H-perfluoro(2,5-dimethyl-4,6-dioxanonanoyl)acrylate.

(Graft Copolymer 3)
Graft copolymer 3 was obtained in the same manner as for graft copolymer 1, except that 40 parts of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanoyl)acrylate was used instead of 1H,1H-perfluoro(4,7-dioxanonanoyl)acrylate.

(Graft Copolymer 4)
Graft copolymer 4 was obtained in the same manner as in graft copolymer 1, except that 55 parts of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanoyl)acrylate was used instead of 1H,1H-perfluoro(3,6-dimethyl-4,7-dioxadecanoyl)acrylate.

(Graft Copolymer 5)
Graft copolymer 5 was obtained in the same manner as in graft copolymer 1, except that the amounts of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanoyl)acrylate and the macromonomer represented by formula (A) were changed to 2.5 parts and 570 parts, respectively.

(Graft Copolymer 6)
Graft copolymer 6 was obtained in the same manner as in graft copolymer 1, except that the amount of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanoyl)acrylate was changed to 12.5 parts and the amount of the macromonomer represented by formula (A) was changed to 450 parts.

(Graft Copolymer 7)
Graft copolymer 7 was obtained in the same manner as in graft copolymer 1, except that the amounts of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanoyl)acrylate and the macromonomer represented by formula (A) were changed to 25 parts and 300 parts, respectively.

(Graft Copolymer 8)
Graft copolymer 8 was obtained in the same manner as in graft copolymer 1, except that the amounts of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanoyl)acrylate and the macromonomer represented by formula (A) were changed to 35 parts and 180 parts, respectively.

(Graft Copolymer 9)
Graft Copolymer 9 was obtained in the same manner as Graft Copolymer 1, except that 56.25 parts of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanoyl)acrylate was used.

(Graft Copolymer 10)
Graft copolymer 10 was obtained in the same manner as in the preparation of graft copolymer 1, except that 0.819 parts of 1,1'-azobis(1-acetoxy-1-phenylethane) was used.

(Graft Copolymer 11)
Graft copolymer 11 was obtained in the same manner as in the preparation of graft copolymer 1, except that 0.728 parts of 1,1'-azobis(1-acetoxy-1-phenylethane) was used.

(Graft Copolymer 12)
Graft copolymer 12 was obtained in the same manner as in the preparation of graft copolymer 1, except that 0.164 parts of 1,1'-azobis(1-acetoxy-1-phenylethane) was used.

(Graft Copolymer 13)
Graft copolymer 13 was obtained in the same manner as in the preparation of graft copolymer 1, except that 0.131 parts of 1,1'-azobis(1-acetoxy-1-phenylethane) was used.

(Graft Copolymer 14)
Graft copolymer 14 was obtained in the same manner as in the preparation of graft copolymer 1, except that 0.874 parts of 1,1'-azobis(1-acetoxy-1-phenylethane) was used.

(Graft Copolymer 15)
Graft Copolymer 15 was obtained in the same manner as Graft Copolymer 1, except that 0.119 parts of 1,1'-azobis(1-acetoxy-1-phenylethane) was used.

(Graft Copolymer 16)
Graft copolymer 16 was obtained in the same manner as in Graft copolymer 1, except that the amount of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanoyl)acrylate was changed to 20 parts and the amount of the macromonomer represented by formula (A) was changed to 360 parts.

(Graft Copolymer 17)
Graft copolymer 17 was obtained in the same manner as in Graft copolymer 1, except that 50 parts of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanoyl)acrylate and 30 parts of the macromonomer represented by formula (A) were used.

(Graft Copolymer 18)
Graft copolymer 18 was obtained in the same manner as for graft copolymer 1, except that 25 parts of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanoyl)acrylate was used instead of 1H,1H-perfluoro(3,5-dioxahexanoyl)acrylate.

(Graft Copolymer 19)
Graft copolymer 19 was obtained in the same manner as in Graft copolymer 1, except that 35 parts of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanoyl)acrylate was used instead of 1H,1H-perfluoro(3,6-dioxaoctanoyl)acrylate.

(Graft Copolymer 20)
Graft copolymer 20 was obtained in the same manner as for graft copolymer 1, except that 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanoyl)acrylate was changed to 1H,1H-perfluoro(4,7-dioxaundecanoyl)acrylate.

(Graft Copolymer 21)
Graft copolymer 21 was obtained in the same manner as graft copolymer 1, except that 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanoyl)acrylate was changed to 1H,1H,2H,2H-perfluoro(3,6-dimethyl-4,7-dioxadecanoyl)acrylate.

(Graft Copolymer 22)
Graft copolymer 22 was obtained in the same manner as for graft copolymer 1, except that 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanoyl)acrylate was changed to 1H,1H,2H,2H-perfluoro(4,7-dioxaundecanoyl)acrylate.

The resulting graft copolymers 1 to 22 were subjected to GPC measurement using the method described above, and the weight-average molecular weights were calculated. The results are shown in Table 3.

<Preparation of Electrophotographic Photoreceptor>
Example 1-1
(Support 1)
A cylindrical aluminum cylinder (JIS-A3003, aluminum alloy, outer diameter 30.6 mm, length 370 mm, wall thickness 1 mm) was used as a support (conductive support). It was subjected to ultrasonic cleaning in a cleaning solution containing pure water and detergent (product name: Chemicol CT, manufactured by Tokiwa Chemical Co., Ltd.), and after the cleaning solution was rinsed off, it was further subjected to ultrasonic cleaning in pure water and degreased. This was designated as support 1.

(Undercoat layer 1)
100 parts of zinc oxide particles (specific surface area: 19 m ² /g, powder resistivity: 4.7 × 10 ⁶ Ω·cm) were mixed with 500 parts of toluene under stirring, and 0.8 parts of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, product name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) was added thereto and stirred for 6 hours. Thereafter, the toluene was distilled off under reduced pressure, and the mixture was dried by heating at 130°C for 6 hours to obtain surface-treated zinc oxide particles A.

Next, 15 parts of butyral (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) as a polyol and 15 parts of blocked isocyanate (trade name: Duranate TPA-B80E, nonvolatile content 80% by mass, manufactured by Asahi Kasei Chemicals Corporation) were dissolved in a mixed solvent of 73.5 parts of methyl ethyl ketone and 73.5 parts of 1-butanol. To this solution, 80.8 parts of surface-treated zinc oxide particles A and 0.81 parts of 2,3,4-trihydroxybenzophenone (manufactured by Tokyo Chemical Industry Co., Ltd.) were added, and the mixture was dispersed in a sand mill using glass beads with a diameter of 0.8 mm in an atmosphere of 23±3°C for 3 hours.
After the dispersion treatment, 0.01 parts of silicone oil (trade name: SH28PA, manufactured by Dow Corning Toray Co., Ltd. (formerly Dow Corning Toray Silicone Co., Ltd.)) and 5.6 parts of crosslinked polymethyl methacrylate (PMMA) particles (trade name: Techpolymer SSX-103, manufactured by Sekisui Plastics Co., Ltd., average primary particle size: 3 μm) were added and stirred to prepare a coating liquid for an undercoat layer.
The obtained coating liquid for undercoat layer was dip-coated onto the support 1 to form a coating film, and the coating film was dried at 160° C. for 30 minutes to form an undercoat layer 1 having a thickness of 18 μm.

(Charge Generation Layer 1)
Four parts of hydroxygallium phthalocyanine crystals (charge generating material) having strong peaks at Bragg angles 2θ±0.2°, 7.4° and 28.1°, in CuKα characteristic X-ray diffraction, and 0.04 parts of a compound represented by the following formula (E) were added to a solution prepared by dissolving 2 parts of polyvinyl butyral (trade name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.) in 100 parts of cyclohexanone. The mixture was then dispersed for 1 hour in a sand mill using 1 mm diameter glass beads in an atmosphere of 23±3°C, and after the dispersion treatment, 100 parts of ethyl acetate was added to prepare a coating solution for a charge generating layer.
This charge generating layer coating liquid was dip coated onto the undercoat layer 1, and the resulting coating was dried at 90° C. for 10 minutes to form a charge generating layer 1 having a thickness of 0.15 μm.

(Charge transport layer 1)
A coating solution for a charge transport layer was prepared by dissolving 60 parts of a compound represented by the following formula (F), 30 parts of a compound represented by the following formula (G), 10 parts of a compound represented by the following formula (H), 100 parts of a bisphenol Z-type polycarbonate resin (trade name: Iupilon Z400, manufactured by Mitsubishi Engineering-Plastics Corporation), and 0.2 parts of a polycarbonate having a unit represented by the following formula (I) (viscosity average molecular weight Mv: 20,000) in a mixed solvent of 272 parts of o-xylene, 256 parts of methyl benzoate, and 272 parts of dimethoxymethane.
This charge transport layer coating liquid was dip coated onto the charge generating layer 1 to form a coating film, and the resulting coating film was dried at 115° C. for 50 minutes to form a charge transport layer 1 having a thickness of 18 μm.
(In formula (I), 0.95 and 0.05 are the molar ratios (copolymerization ratios) of the two units.)

(protective layer)
A dispersant solution was prepared by dissolving 2.20 parts of the above-mentioned graft copolymer 1 in a mixed solvent consisting of 100 parts of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (trade name: AE-3000, manufactured by AGC Inc.) and 100 parts of 1-propanol.
To the resulting dispersant solution, 40 parts of polytetrafluoroethylene resin particles (average primary particle size 210 nm, average circularity 0.85) were added, and the mixture was passed through a high-pressure disperser (product name: Microfluidizer M-110EH, manufactured by Microfluidics, Inc., USA) to obtain a polytetrafluoroethylene resin particle dispersion.

To the obtained polytetrafluoroethylene resin particle dispersion, 75.4 parts of a hole transport compound represented by the following formula (B), 21.9 parts of a compound represented by the following formula (C), and 100 parts of 1-propanol were added, followed by filtration with a Polyflon filter (trade name: PF-040, manufactured by Advantec Toyo Co., Ltd.) to prepare a polytetrafluoroethylene resin particle dispersion (coating liquid for protective layer).

This protective layer coating solution was dip-coated onto the charge transport layer to form a coating film, which was then dried for 5 minutes at 40°C. After drying, the coating film was irradiated with an electron beam for 1.6 seconds in a nitrogen atmosphere at an acceleration voltage of 70 kV and an absorbed dose of 15 kGy. It was then heat-treated for 15 seconds in a nitrogen atmosphere to bring the coating film to a temperature of 135°C. The oxygen concentration from electron beam irradiation to the 15-second heat treatment was 15 ppm. The coating film was then naturally cooled in the atmosphere to a temperature of 25°C, and then heat-treated for 1 hour to bring the coating film to 105°C, forming a surface layer (protective layer) with a thickness of 5 μm.

The content of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether in the surface layer was 5 ppm.

In this way, an electrophotographic photoreceptor having a support and a surface layer was produced before surface polishing.

<Surface treatment of electrophotographic photoreceptor>
(Polishing of Electrophotographic Photoreceptor Before Surface Polishing)
The surface of the electrophotographic photosensitive member before the surface texture formation was polished using the polishing apparatus shown in FIG.
Polishing sheet feed speed: 400 mm/min
Rotation speed of electrophotographic photosensitive member: 450 rpm
Pressing of electrophotographic photosensitive member into backup roller: 3.5 mm
Rotation direction of the abrasive sheet and electrophotographic photosensitive member: with backup roller; outer diameter 100 mm, Asker C hardness 25
The polishing sheet A to be attached to the polishing device was made by mixing the polishing grains used in GC3000 and GC2000 manufactured by Riken Corundum Co., Ltd.
GC3000 (abrasive sheet surface roughness Ra 0.83 μm)
GC2000 (abrasive sheet surface roughness Ra 1.45 μm)
Abrasive sheet A (abrasive sheet surface roughness Ra 1.12 μm)
The polishing time using the polishing sheet A was 20 seconds.

(Measurement of polishing depth L (μm))
The maximum height Rmax of the electrophotographic photosensitive member after polishing was measured in accordance with JIS B 0601 1982 using a surface roughness measuring instrument, Surfcorder SE3500, manufactured by Kosaka Laboratory Co., Ltd. The measurement conditions were set as follows. Measurement was carried out at three arbitrary locations within a 5 mm square area, and the average value was adopted as the polishing depth L (μm). The polishing depth L of the electrophotographic photosensitive member after surface polishing was 0.75 μm. In addition, in Examples 1-2 to 1-25 described later, the polishing depth L of the electrophotographic photosensitive member that was subjected to surface processing was all 0.75 μm.
(Measurement conditions)
Detector: R2 μm
Stylus: 0.7 mN diamond stylus Filter: 2CR
Cutoff value: 0.08 mm
Measurement length: 2.5 mm
Feed speed: 0.1 mm

[Examples 1-2 to 1-13, 1-22 to 1-27, Comparative Examples 1-1 to 1-3]
An electrophotographic photoreceptor was produced in the same manner as in Example 1-1, except that in forming the protective layer, graft copolymer 1 was changed to the graft copolymer shown in Table 4. The content of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether in the surface layer is shown in Table 4.

[Examples 1-14 to 1-15, 1-20 to 1-21]
An electrophotographic photoreceptor was produced in the same manner as in Example 1-1, except that in forming the protective layer, the amount of graft copolymer 1 was changed to the part by mass shown in Table 4. The content of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether in the surface layer is shown in Table 4.

Examples 1-16 to 1-19
An electrophotographic photoreceptor was produced in the same manner as in Example 1-1, except that in forming the protective layer, polytetrafluoroethylene resin particles having the average primary particle size and average circularity shown in Table 4 were used. The content of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether in the surface layer is shown in Table 4.

Example 2-1
(Support 2)
A cylindrical aluminum cylinder (JIS-A3003, aluminum alloy, outer diameter 30 mm, length 357.5 mm, wall thickness 0.7 mm) was used as a support (conductive support) by cutting. It was subjected to ultrasonic cleaning in a cleaning solution containing pure water and detergent (product name: Chemicol CT, manufactured by Tokiwa Chemical Co., Ltd.), and after the cleaning solution was rinsed off, it was further subjected to ultrasonic cleaning in pure water for degreasing. This was designated as support 2.

(Undercoat layer 2)
60 parts of zinc oxide particles (average particle size: 70 nm, specific surface area: 15 ^m /g) were mixed with 500 parts of tetrahydrofuran by stirring, and 0.75 parts of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, product name: KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.) was added thereto and stirred for 2 hours. Thereafter, tetrahydrofuran was distilled off under reduced pressure, and the mixture was dried by heating at 120°C for 3 hours to obtain surface-treated zinc oxide particles.

Next, 25 parts of butyral (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) as a polyol and 22.5 parts of blocked isocyanate (trade name: Sumidur BL-3173, manufactured by Sumitomo Bayer Urethane Co., Ltd.) were dissolved in 142 parts of methyl ethyl ketone. To this solution, 100 parts of the surface-treated zinc oxide particles and 1 part of alizarin were added, and the mixture was dispersed for 5 hours in a sand mill using glass beads with a diameter of 1 mm.
After the dispersion treatment, 0.008 parts of dioctyltin dilaurate and 6.5 parts of silicone resin particles (Tospearl 145, manufactured by GE Toshiba Silicones Co., Ltd.) were added and stirred to prepare a coating liquid for an undercoat layer.
The obtained coating liquid for undercoat layer was dip-coated onto the support 2 to form a coating film, and the coating film was dried at 190° C. for 24 minutes to form an undercoat layer 2 with a thickness of 15 μm.

(Charge Generation Layer 2)
Next, 15 parts of chlorogallium phthalocyanine crystals having strong diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.4°, 16.6°, 25.5°, and 28.3° with respect to CuKα characteristic X-rays, 10 parts of vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Union Carbide Co., Ltd.), and 300 parts of n-butyl alcohol were mixed and dispersed for 4 hours in a sand mill using glass beads with a diameter of 1 mm to prepare a coating solution for a charge generating layer.
This charge generating layer coating liquid was dip coated onto the undercoat layer 2, and the resulting coating was dried at 150° C. for 5 minutes to form a charge generating layer 2 having a thickness of 0.2 μm.

(charge transport layer)
Next, 10 parts of polytetrafluoroethylene resin particles (average primary particle size 210 nm, average circularity 0.85), 0.50 parts of the above-mentioned graft copolymer 1, and 24 parts of tetrahydrofuran were mixed and stirred for 48 hours while maintaining a liquid temperature of 20°C, to obtain Preparation A.
Next, 53.2 parts of N,N'-bis(3-methylphenyl)-N,N'-diphenylbenzidine, 14.1 parts of bisphenol Z-type polycarbonate resin (viscosity average molecular weight 40,000), and 0.26 parts of 2,6-di-t-butyl-4-methylphenol as an antioxidant were mixed, and 250 parts of tetrahydrofuran was added and dissolved to obtain Preparation B.
Preparation A was added to Preparation B and mixed with stirring, and then passed through a high-pressure disperser (trade name: Microfluidizer M-110EH, manufactured by Microfluidics, Inc., USA) to obtain a dispersion.

Thereafter, fluorine-modified silicone oil (product name: FL-100, manufactured by Shin-Etsu Silicones Co., Ltd.) was added to the dispersion to a concentration of 5 ppm, and the dispersion was filtered through a Polyflon filter (product name: PF-040, manufactured by Advantec Toyo Co., Ltd.) to prepare a coating liquid for the charge transport layer.
This charge transport layer coating liquid was dip coated onto the charge generating layer 2 to form a coating film, and the resulting coating film was dried at 150° C. for 25 minutes to form a charge transport layer with a thickness of 30 μm.
In this way, an electrophotographic photoreceptor was prepared.

[Examples 2-2 to 2-13, 2-22 to 2-27, Comparative Examples 2-1 to 2-3]
An electrophotographic photoreceptor was produced in the same manner as in Example 2-1, except that the graft copolymer 1 was changed to the graft copolymer shown in Table 5 in forming the charge transport layer.

[Examples 2-14 to 2-15, 2-20 to 2-21]
An electrophotographic photoreceptor was prepared in the same manner as in Example 2-1, except that the amount of graft copolymer 1 was changed to the parts by mass shown in Table 5 in forming the charge transport layer.

Examples 2-16 to 2-19
An electrophotographic photoreceptor was produced in the same manner as in Example 2-1, except that in forming the charge transport layer, the polytetrafluoroethylene resin particles were changed to polytetrafluoroethylene resin particles having the average primary particle size and average circularity shown in Table 5.

<Evaluation of Electrophotographic Photoreceptors>
The electrophotographic photoreceptors obtained in Examples 1-1 to 1-27, 2-1 to 2-27, and Comparative Examples 1-1 to 1-3, 2-1 to 2-3 were evaluated as follows.

[Evaluation Device 1-1]
The electrophotographic photoreceptors prepared in Examples 1-1 to 1-27 and Comparative Examples 1-1 to 1-3 were mounted on a copying machine, ImagePRESS C800 (product name), manufactured by Canon Inc., and evaluated.
Specifically, the evaluation device was placed in an environment of a temperature of 23°C and a relative humidity of 50% RH, and the prepared electrophotographic photosensitive member was mounted in a magenta process cartridge, which was then mounted in the station of the magenta process cartridge, and evaluation was performed.

[Evaluation Device 1-2]
The electrophotographic photoreceptors prepared in Examples 1-1 to 1-27 and Comparative Examples 1-1 to 1-3 were mounted on a modified copy machine, ImagePRESS C800 (product name), manufactured by Canon Inc. The charging means of the modified machine was a charging means of a type that applies a voltage in which an AC voltage is superimposed on a DC voltage to a roller-type contact charging member (charging roller), and the exposure means was an exposure means of a laser image exposure type (wavelength 680 nm).
Specifically, the evaluation device was placed in an environment of a temperature of 23°C and a relative humidity of 50% RH, and the prepared electrophotographic photosensitive member was mounted in a magenta process cartridge, which was then mounted in the station of the magenta process cartridge, and evaluation was performed.
The charging conditions were adjusted so that the charging potential was −800V and the exposure potential was −300V, and the charging potential and the exposure amount of the exposure means were adjusted.

The surface potential of the electrophotographic photosensitive member was measured by removing the developing cartridge from the evaluation device and inserting a potential measuring device therein. The potential measuring device was configured by placing a potential measuring probe (product name: model 6000B-8, manufactured by Trek Japan Co., Ltd.) at the development position of the developing cartridge. The potential measuring probe was positioned relative to the electrophotographic photosensitive member at the center in the generating line direction of the electrophotographic photosensitive member, with a gap of 3 mm from the surface of the electrophotographic photosensitive member. Furthermore, the potential at the center of the electrophotographic photosensitive member was measured using a surface potentiometer (product name: model 344, manufactured by Trek Japan Co., Ltd.).

[Evaluation Device 2-1]
The electrophotographic photoreceptors prepared in Examples 2-1 to 2-27 and Comparative Examples 2-1 to 2-3 were mounted on a copying machine imageRUNNER iR-ADV C5051 manufactured by Canon Inc. and evaluated.
Specifically, the evaluation device was placed in an environment of a temperature of 23° C. and a relative humidity of 50% RH, and the prepared electrophotographic photosensitive member was attached to a process cartridge for cyan color, which was then attached to the station of the cyan process cartridge, and evaluation was carried out.

[Evaluation Device 2-2]
The electrophotographic photoreceptors prepared in Examples 2-1 to 2-27 and Comparative Examples 2-1 to 2-3 were mounted on a modified copy machine imageRUNNER iR-ADV C5051 manufactured by Canon Inc. (charging means was a system in which a voltage in which an AC voltage was superimposed on a DC voltage was applied to a roller-type contact charging member (charging roller), and exposure means was a laser image exposure system (wavelength 780 nm)), and evaluations were carried out.
Specifically, the evaluation device was placed in an environment of a temperature of 23° C. and a relative humidity of 50% RH, and the prepared electrophotographic photosensitive member was attached to a process cartridge for cyan color, which was then attached to the station of the cyan process cartridge, and evaluation was carried out.
The charging conditions were adjusted so that the charging potential was −700V and the exposure potential was −200V, and the charging potential and the exposure amount of the exposure means were adjusted.
The surface potential of the electrophotographic photosensitive member was measured by removing the developing cartridge from the evaluation device and inserting a potential measuring device therein. The potential measuring device was configured by disposing a potential measuring probe (trade name: model 6000B-8, manufactured by Trek Japan Co., Ltd.) at the development position of the developing cartridge, and the position of the potential measuring probe relative to the electrophotographic photosensitive member was the center in the generatrix direction of the electrophotographic photosensitive member, with a gap of 3 mm from the surface of the electrophotographic photosensitive member. Furthermore, the potential at the center of the electrophotographic photosensitive member was measured using a surface potentiometer (trade name: model 344, manufactured by Trek Japan Co., Ltd.).

(Initial image evaluation)
Image evaluation was performed using the above-mentioned evaluation device 1-1 and evaluation device 2-1. A solid white image was output using A4-size gloss paper, and the number of image defects due to poor dispersion contained in the area of one circumference of the electrophotographic photosensitive member of the output image, i.e., the number of black dots, was visually evaluated according to the following evaluation ranks. The area of one circumference of the electrophotographic photosensitive member is a rectangular region whose length is 297 mm, which is the long side length of A4 paper, and whose width is 94.2 mm, which is one circumference of the electrophotographic photosensitive member. In addition, in the present disclosure, ranks A, B, C, and D represent levels at which the effects of the present disclosure are obtained, and among them, rank A was determined to be an excellent level. On the other hand, rank E was determined to be a level at which the effects of the present disclosure are not obtained.
A: No black dots at all B: 1 to 3 black dots less than 1.5 mm in diameter, and no black dots 1.5 mm or larger C: 1 to 3 black dots less than 1.5 mm in diameter, and 1 to 2 black dots 1.5 mm or larger D: 4 to 5 black dots less than 1.5 mm in diameter, and 2 or smaller black dots 1.5 mm or larger E: 6 or more black dots less than 1.5 mm in diameter, or 3 or more black dots 1.5 mm or larger The results of the evaluation are shown in Table 6.

(Evaluation of potential fluctuations during repeated use)
The evaluation of potential fluctuations during repeated use was carried out using the above-mentioned evaluation device 1-2 and evaluation device 2-2. A cartridge equipped with an electrophotographic photosensitive member was attached to the evaluation device, and the photosensitive member was repeatedly used by passing 10,000 sheets of paper. At the station where the electrophotographic photosensitive member was installed, 10,000 sheets of A4-sized plain paper were repeatedly image-formed with a monochrome character image at a printing rate of 1%. The initial dark potential at this time was compared with the dark potential after 10,000 sheets of repeated image formation, and this was taken as the potential fluctuation value (ΔVd). Furthermore, the initial light potential was compared with the light potential after 10,000 sheets of repeated image formation, and this was taken as the potential fluctuation value (ΔVl). After passing 10,000 sheets of paper, the cartridge was left for 5 minutes, the developing cartridge was replaced with a potential measuring device, and the light potential (Vlb) and dark potential (Vdb) after repeated use were measured. The difference between the dark potential after repeated use and the initial dark potential (Vda) was defined as the dark potential fluctuation (ΔVd = |Vdb| - |Vda|). The difference between the light potential after repeated use and the initial light potential (Vla) was defined as the light potential fluctuation (ΔVl = |Vlb| - |Vla|). In the evaluation using evaluation device 1-2, the light potential fluctuation was measured after repeated use of 100,000 sheets, 300,000 sheets, and 500,000 sheets. In the evaluation using evaluation device 2-2, the light potential fluctuation was measured after repeated use of 100,000 sheets.
In the present disclosure, when the change in bright area potential is within 40 V, it is determined that the effect of the present disclosure is achieved, and among these, when the change in bright area potential is within 15 V, it is determined that it is a particularly excellent level.
The results of the evaluation are shown in Table 6.

101 Support 102 Undercoat layer 103 Charge generating layer 104 Charge transport layer 105 Surface layer (protective layer)
201 Electrophotographic photosensitive member 202 Shaft 203 Charging means 204 Exposure light 205 Developing means 206 Transfer means 207 Transfer material 208 Fixing means 209 Cleaning means 210 Pre-exposure light 211 Process cartridge 212 Guide means 1 Electrophotographic photosensitive member 2 Charging means 3 Exposure light (image exposure light)
4 Developing means 5 Transfer means 6 Transfer material 7 Pre-exposure light 8 Cleaning means 9 Process cartridge 10 Intermediate transfer body 11 Transfer paper 12 Paper feed path 13 Paper feed tray 14 Secondary transfer means 15 Fixing means 16 Paper discharge section 17 Yellow process cartridge 18 Magenta process cartridge 19 Cyan process cartridge 20 Black process cartridge

Claims (21)

An electrophotographic photoreceptor having a surface layer,
The surface layer is
fluorine atom-containing resin particles;
A binding material;
A polymer A having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2) ,
Contains
the polymer A does not have a structural unit having an acidic group having a pKa of 3 or less;
An electrophotographic photoreceptor characterized by the above-mentioned.
(In formula (1),
R ¹¹ represents a hydrogen atom or a methyl group;
R ¹² represents a single bond or a methylene group;
^Rf1 and ^Rf2 each independently represent a perfluoroalkylene group having 1 to 3 carbon atoms or a perfluoroalkylidene group having 1 to 3 carbon atoms;
^Rf3 represents a perfluoroalkyl group having 1 to 3 carbon atoms.
(In formula (2),
Y ^A1 represents an unsubstituted alkylene group;
YB ^represents an unsubstituted alkylene group, an alkylene group substituted with a halogen atom, an alkylene group substituted with a hydroxy group, an ester bond (-COO-), an amide bond (-NHCO-), a urethane bond (-NHCOO-), or a divalent linking group derived by combining one or more selected from these groups and bonds with -O- or -S-, or a single bond;
Z ^A represents a structure represented by the following formula (2A), a cyano group, or a phenyl group:
R ²¹ and R ²² each independently represent a hydrogen atom or a methyl group;
m is an integer of 25 or more and 150 or less.
(In formula (2A), Z ^represents an alkyl group having 1 to 4 carbon atoms.) An electrophotographic photoreceptor having a surface layer,
The surface layer is
fluorine atom-containing resin particles;
A binding material;
A polymer A having a structural unit represented by the following formula (1),
Contains
the content of the polymer A is 2% by mass or more and 10% by mass or less relative to the mass of the fluorine atom-containing resin particles in the surface layer,
the polymer A does not have a structural unit having an acidic group having a pKa of 3 or less;
An electrophotographic photoreceptor characterized by:
(In formula (1),
R ¹¹ represents a hydrogen atom or a methyl group,
R ¹² represents a single bond or a methylene group,
Rf ¹ and Rf ² each independently represents a perfluoroalkylene group having 1 to 3 carbon atoms or a perfluoroalkylidene group having 1 to 3 carbon atoms,
Rf ³ represents a perfluoroalkyl group having 1 to 3 carbon atoms. An electrophotographic photoreceptor having a surface layer,
The surface layer is
fluorine atom-containing resin particles;
A binding material;
A polymer A having a structural unit represented by the following formula (1),
Contains
the content of the structural unit represented by formula (1) in the polymer A is 5% by number or more and 95% by number or less based on the total number of structural units in the polymer A,
the polymer A does not have a structural unit having an acidic group having a pKa of 3 or less;
An electrophotographic photoreceptor characterized by the above-mentioned.
(In formula (1),
R ¹¹ represents a hydrogen atom or a methyl group,
R ¹² represents a single bond or a methylene group,
Rf ¹ and Rf ² each independently represents a perfluoroalkylene group having 1 to 3 carbon atoms or a perfluoroalkylidene group having 1 to 3 carbon atoms,
Rf ³ represents a perfluoroalkyl group having 1 to 3 carbon atoms. The electrophotographic photoreceptor according to claim 1 or 2, wherein the content of the structural unit represented by formula (1) in polymer A is 5% by number or more and 95% by number or less of all structural units in polymer A. 4. The electrophotographic photoreceptor according to claim 1 , wherein the content of the polymer A in the surface layer is from 2% by mass to 10% by mass with respect to the mass of the fluorine atom-containing resin particles in the surface layer. The electrophotographic photoreceptor according to any one of claims 2 to 5 , wherein the polymer A further has a structural unit represented by the following formula (2):
(In formula (2),
Y ^A1 represents an unsubstituted alkylene group;
^YB represents an unsubstituted alkylene group, an alkylene group substituted with a halogen atom, an alkylene group substituted with a hydroxy group, an ester bond (-COO-), an amide bond (-NHCO-), a urethane bond (-NHCOO-), or a divalent linking group derived by combining one or more selected from these groups and bonds with -O- or -S-, or a single bond;
Z ^A represents a structure represented by the following formula (2A), a cyano group, or a phenyl group:
R ²¹ and R ²² each independently represent a hydrogen atom or a methyl group;
m is an integer of 25 or more and 150 or less.
(In formula (2A), ^Z represents an alkyl group having 1 to 4 carbon atoms.) Rf in the formula (1) ¹ ~Rf ³ 7. The electrophotographic photoreceptor according to claim 1, wherein the total number of carbon atoms is 6 or more and 9 or less. The electrophotographic photoreceptor according to any one of claims 1 to 7, wherein the content of the structural unit represented by formula (1) in the polymer A is 0.1% by mass or more and 80% by mass or less with respect to all structural units in the polymer A. 9. The electrophotographic photoreceptor according to claim 1, wherein the weight average molecular weight of the polymer A is 16,000 or more and 100,000 or less. 8. The electrophotographic photoreceptor according to claim 1, wherein the polymer A has, as structural units, only the structural unit represented by the formula (1) and the structural unit represented by the formula (2). 11. The electrophotographic photoreceptor according to claim 1, wherein the ratio of the structural unit represented by formula (1) to the structural unit represented by formula (2) in polymer A is 1:19 to 19:1 in terms of molar ratio. 12. The electrophotographic photoreceptor according to claim 1 , wherein the content of the fluorine atom-containing resin particles in the surface layer is 5% by mass or more and 40% by mass or less with respect to the total mass of the surface layer. 13. The electrophotographic photoreceptor according to claim 1, wherein the binder material is a cured product of a hole transporting compound having a chain-polymerizable functional group. 14. The electrophotographic photoreceptor according to claim 13 , wherein the hole transporting compound having a chain polymerizable functional group is a compound represented by the following formula (CT-1) or (CT-2):
(In the formula (CT-1), Ar ¹¹ to Ar ¹³ each independently represent a substituted aryl group or an unsubstituted aryl group, and the substituent that the substituted aryl group may have is an alkyl group having 1 to 6 carbon atoms, or a monovalent functional group represented by any one of the following formulae (P-1) to (P-3), with the proviso that the compound represented by the formula (CT-1) has at least one monovalent functional group represented by any one of the following formulae (P-1) to (P-3).)
(In the formula (CT-2), Ar ²¹ to Ar ²⁴ each independently represent a substituted aryl group or an unsubstituted aryl group; Ar ²⁵ represents a substituted arylene group or an unsubstituted arylene group; the substituent that the substituted aryl group may have is an alkyl group having 1 to 6 carbon atoms or a monovalent functional group represented by the following formulas (P-1) to (P-3); the substituent that the substituted arylene group may have is an alkyl group having 1 to 6 carbon atoms or a monovalent functional group represented by the following formulas (P-1) to (P-3); and the compound represented by the formula (CT-2) has at least one monovalent functional group represented by any of the following formulas (P-1) to (P-3).)
(In the formula (P-1), Z ¹¹ represents a single bond or an alkylene group having 1 to 6 carbon atoms, and X ¹¹ represents a hydrogen atom or a methyl group.)
(In the formula (P-2), Z ²¹ represents a single bond or an alkylene group having 1 to 6 carbon atoms.)
(In the formula (P-3), Z ³¹ represents a single bond or an alkylene group having 1 to 6 carbon atoms.) The electrophotographic photoreceptor according to any one of claims 1 to 14, wherein the content of the fluorine atom-containing resin particles in the surface layer is 20% by mass or more and 40% by mass or less with respect to the total mass of the surface layer. The electrophotographic photoreceptor according to any one of claims 1 to 15, wherein the surface layer further contains a compound represented by the following formula (3):
(In formula (3), R ³¹ represents an alkyl group or a fluoroalkyl group, and R ³² represents a fluoroalkyl group.) A process cartridge that integrally supports the electrophotographic photosensitive member according to any one of claims 1 to 16 and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, and is detachably mountable to the main body of an electrophotographic apparatus. An electrophotographic apparatus comprising the electrophotographic photoreceptor according to any one of claims 1 to 16, as well as a charging unit, an exposure unit, a developing unit, and a transfer unit. A method for manufacturing an electrophotographic photoreceptor having a surface layer, comprising:
The manufacturing method comprises:
a step of preparing a surface layer coating liquid containing a polymer A having a structural unit represented by the following formula (1) and a structural unit represented by the following formula (2) , at least one selected from a binder material and a raw material for the binder material, and fluorine atom-containing resin particles; and
a step of forming a coating film of the surface layer coating liquid and drying and/or curing the coating film to form the surface layer;
1. A method for producing an electrophotographic photoreceptor, comprising:
(In formula (1),
R ¹¹ represents a hydrogen atom or a methyl group;
R ¹² represents a single bond or a methylene group;
^Rf1 and ^Rf2 each independently represent a perfluoroalkylene group having 1 to 3 carbon atoms or a perfluoroalkylidene group having 1 to 3 carbon atoms;
^Rf3 represents a perfluoroalkyl group having 1 to 3 carbon atoms.
(In formula (2),
Y ^A1 represents an unsubstituted alkylene group;
YB ^represents an unsubstituted alkylene group, an alkylene group substituted with a halogen atom, an alkylene group substituted with a hydroxy group, an ester bond (-COO-), an amide bond (-NHCO-), a urethane bond (-NHCOO-), or a divalent linking group derived by combining one or more selected from these groups and bonds with -O- or -S-, or a single bond;
Z ^A represents a structure represented by the following formula (2A), a cyano group, or a phenyl group:
R ²¹ and R ²² each independently represent a hydrogen atom or a methyl group;
m is an integer of 25 or more and 150 or less.
(In formula (2A), Z ^represents an alkyl group having 1 to 4 carbon atoms.) A method for manufacturing an electrophotographic photoreceptor having a surface layer, comprising:
The manufacturing method comprises:
a step of preparing a surface layer coating liquid containing a polymer A having a structural unit represented by the following formula (1), at least one selected from a binder material and a raw material for the binder material, and fluorine atom-containing resin particles; and
a step of forming a coating film of the surface layer coating liquid and drying and/or curing the coating film to form the surface layer;
and
the content of the polymer A is 2% by mass or more and 10% by mass or less relative to the mass of the fluorine atom-containing resin particles in the surface layer;
10. A method for producing an electrophotographic photosensitive member, comprising:
(In formula (1),
R ¹¹ represents a hydrogen atom or a methyl group,
R ¹² represents a single bond or a methylene group,
Rf ¹ and Rf ² each independently represents a perfluoroalkylene group having 1 to 3 carbon atoms or a perfluoroalkylidene group having 1 to 3 carbon atoms,
Rf ³ represents a perfluoroalkyl group having 1 to 3 carbon atoms. A method for manufacturing an electrophotographic photoreceptor having a surface layer, comprising:
The manufacturing method comprises:
a step of preparing a surface layer coating liquid containing a polymer A having a structural unit represented by the following formula (1), at least one selected from a binder material and a raw material for the binder material, and fluorine atom-containing resin particles; and
a step of forming a coating film of the surface layer coating liquid and drying and/or curing the coating film to form the surface layer;
have
the content of the structural unit represented by formula (1) in the polymer A is 5% by number or more and 95% by number or less of all structural units in the polymer A;
10. A method for producing an electrophotographic photosensitive member, comprising:
(In formula (1),
R ¹¹ represents a hydrogen atom or a methyl group,
R ¹² represents a single bond or a methylene group,
Rf ¹ and Rf ² each independently represents a perfluoroalkylene group having 1 to 3 carbon atoms or a perfluoroalkylidene group having 1 to 3 carbon atoms,
Rf ³ represents a perfluoroalkyl group having 1 to 3 carbon atoms.