Electrophotographic photoreceptor, process cartridge, electrophotographic device, and method of manufacturing electrophotographic photoreceptor

Abstract

To provide an electrophotographic photoreceptor which comprises a surface layer that features superior dispersibility of fluorine atom-containing resin particles and suppresses electric potential variations associated with repetitive use.SOLUTION: An electrophotographic photoreceptor is provided, comprising a surface layer containing fluorine atom-containing resin particles, a binder resin, and a polymer having a specific repeating unit.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present disclosure relates to an electrophotographic photoreceptor, a process cartridge having the electrophotographic photoreceptor, an electrophotographic apparatus, and a method for manufacturing the electrophotographic photoreceptor.

Background Art

[0002] As an electrophotographic photoreceptor mounted in an electrophotographic apparatus, those containing an organic photoconductive substance (charge generating substance) are widely used. In recent years, for the purpose of extending the life of the electrophotographic photoreceptor and improving the image quality during repeated use, an improvement in the mechanical durability (abrasion resistance) of the electrophotographic photoreceptor has been demanded.

[0003] As a technique for improving the abrasion resistance of an electrophotographic photoreceptor, there is a method of reducing the friction between the surface layer of the electrophotographic photoreceptor and a contact member such as a cleaning blade by incorporating fluorine atom-containing resin particles into the surface layer. In Patent Document 1, a technique for forming a surface layer by using a dispersion liquid of fluorine atom-containing resin particles such as polytetrafluoroethylene resin particles as a coating liquid for the surface layer is disclosed.

[0004] Further, when preparing a dispersion liquid of fluorine atom-containing resin particles, a method of using a (meth)acrylic polymer containing fluorine atoms as a dispersant for the fluorine atom-containing resin particles for the purpose of enhancing the dispersibility is known. In Patent Document 2 and Patent Document 3, techniques for improving the dispersibility of fluorine atom-containing resin particles by using a fluorine atom-containing (meth)acrylic polymer having a specific structure as a dispersant are disclosed.

[0005] Patent Document 4 discloses an electrophotographic photoreceptor having a outermost surface layer containing a fluorine-based graft polymer and fluorine-containing resin particles, and the fluorine-based graft polymer contains a structural unit having an acidic group with a pKa of 3 or less.

Prior Art Documents

Patent Documents

[0006] [Patent Document 1] Japanese Patent Application Publication No. 06-332219 [Patent Document 2] Japanese Patent Publication No. 2012-189715 [Patent Document 3] Japanese Patent Publication No. 2009-104145 [Patent Document 4] Japanese Patent Publication No. 2021-47236 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] However, while the technologies disclosed in Patent Documents 2 and 3 yield a surface layer with excellent dispersibility of fluorine atom-containing resin particles, potential fluctuations were sometimes not sufficiently suppressed during repeated use of the electrophotographic photoreceptor. In particular, electrophotographic photoreceptors with a surface layer that has excellent abrasion resistance, intended for extended lifespan, faced the problem of large potential fluctuations during long-term repeated use. Therefore, there was room for improvement in suppressing potential fluctuations during repeated use of electrophotographic photoreceptors.

[0008] One aspect of this disclosure is aimed at providing an electrophotographic photoreceptor in which potential fluctuations during repeated use are suppressed. Another aspect of this disclosure relates to a process cartridge equipped with the electrophotographic photoreceptor, and an electrophotographic apparatus equipped with the process cartridge. Another aspect of this disclosure is toward providing a method for manufacturing the electrophotographic photoreceptor. [Means for solving the problem]

[0009] According to one aspect of the present disclosure, an electrophotographic photoreceptor having a surface layer, wherein the surface layer contains fluorine atom-containing resin particles, a binder material, and a polymer A having structural units represented by the following formula (1), and the polymer A does not have structural units having acidic groups with a pKa of 3 or less. [ka] (In formula (1), R 11 R represents a hydrogen atom or a methyl group. 12 Rf indicates a single bond or a methylene group. 1 and Rf 2 Each of these independently represents either a perfluoroalkylene group having 1 to 3 carbon atoms, or a perfluoroalkylidene group having 1 to 3 carbon atoms. Rf 3 (This represents a perfluoroalkyl group with 1 to 3 carbon atoms.) An electrophotographic photoreceptor is provided, characterized by the following features.

[0010] Preferably, the surface layer does not contain polymers having structural units with acidic groups having a pKa of 3 or less.

[0011] Furthermore, according to another aspect of the present disclosure, a process cartridge is provided that integrally supports the electrophotographic photoreceptor and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, and is detachable from the body of an electrophotographic apparatus. Furthermore, according to other aspects of this disclosure, an electrophotographic apparatus is provided having the electrophotographic photoreceptor, as well as a charging means, an exposure means, a developing means, and a transfer means. Furthermore, according to other aspects of this disclosure, a method for manufacturing the electrophotographic photoreceptor is provided. [Effects of the Invention]

[0012] According to one aspect of this disclosure, an electrophotographic photoreceptor can be provided that exhibits excellent dispersibility of fluorine atom-containing resin particles in the surface layer and suppresses potential fluctuations during repeated use. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram showing an example of the configuration of an electrophotographic photoreceptor. [Figure 2] This figure shows an example of a polishing machine using abrasive sheets. [Figure 3]It is a diagram showing an example of a schematic configuration of a process cartridge equipped with an electrophotographic photoreceptor and an electrophotographic apparatus equipped with the process cartridge. [Figure 4] It is a schematic diagram showing an example of a process cartridge having an electrophotographic photoreceptor. [Figure 5] It is a schematic diagram showing an example of an electrophotographic apparatus having an electrophotographic photoreceptor.

Embodiments for Carrying Out the Invention

[0014] As a result of the studies by the present inventors, by including fluorine atom-containing resin particles, a binder material, and a polymer A having a structural unit represented by the following formula (1) in the surface layer of the electrophotographic photoreceptor, excellent in the dispersibility of the fluorine atom-containing resin particles in the surface layer, and an electrophotographic photoreceptor in which potential fluctuations during repeated use are suppressed has been found to be obtained.

Chemical Formula

[0015] 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 having an acidic group with a pKa of 3 or less, but it is preferably not contained.

[0016] 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 alkyl fluoride carboxylic acid groups (e.g., trifluoroacetic acid: -0.25, difluoroacetic acid: 1.24, monofluoroacetic acid: 2.66).

[0017] Here, the inventors believe that polymer A having the structural unit shown in formula (1) acts as a dispersant for fluorine atom-containing resin particles in the process of preparing a coating solution for the surface layer of an electrophotographic photoreceptor.

[0018] The inventors speculate that the electrophotographic photoreceptor of this disclosure exhibits excellent dispersibility of fluorine atom-containing resin particles in the surface layer and excellent suppression of potential fluctuations during repeated use, as follows.

[0019] Electrophotographic photoreceptors having a surface layer containing fluorine atom-containing resin particles and a dispersant tend to exhibit large potential fluctuations during repeated use. This is due to the dispersant adhering to the fluorine atom-containing resin particles contained in the surface layer, which has a (CF2) property. n -This is thought to be because electric charge tends to accumulate in the chain.

[0020] Based on the inventors' investigations, -(CF2) n -When incorporating a polymer having structural units including chains into the surface layer, -(CF2) n -Chains and- (CF2) n -We found that the presence of oxygen atoms between the chain and the oxygen atom has the effect of suppressing charge trapping. However, -(CF2) n - The more carbon atoms in the chain, the easier it is for charge to accumulate, and in some cases, the effect of suppressing potential fluctuations may not be sufficiently obtained.

[0021] As a result of further investigation by the present inventors, it was found that by incorporating polymer A having the structural unit shown in formula (1) into the surface layer, charge trapping is suppressed and an electrophotographic photoreceptor with suppressed potential fluctuations during repeated use can be obtained.

[0022] Rf in equation (1) above 1 and Rf 2 Let Rf be a perfluoroalkylene group having 1 to 3 carbon atoms or a perfluoroalkylidene group having 1 to 3 carbon atoms. 3 The R in formula (1) is set to a perfluoroalkyl group having 1 to 3 carbon atoms. This is thought to suppress the accumulation of charge in the structural unit represented by formula (1). 12 By using a single bond or a methylene group, the difference in surface energy between the structural unit shown in formula (1) and the fluorine atom-containing resin particles is reduced, making it easier for the fluorine atom-containing resin particles to adhere to the structural unit.

[0023] <Fluorine atom-containing resin particles> The surface layer of the electrophotographic photoreceptor of this disclosure contains fluorine atom-containing resin particles. Preferably, the content of fluorine atom-containing resin particles in the surface layer is 5% by mass or more and 40% by mass or less based on the total mass of the surface layer. Examples of resins contained in the fluorine atom-containing resin particles used in this disclosure include: polytetrafluoroethylene resin, polychlorotrifluoroethylene resin, polytetrafluoroethylene propylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, or 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 made of polytetrafluoroethylene (PTFE) resin.

[0024] In cross-sectional observation of the surface layer, it is preferable that the arithmetic mean of the major axis of the primary particles (average primary particle size) measured from the secondary electron image obtained by scanning electron microscopy is between 150 nm and 300 nm, from the viewpoint of improving dispersibility and suppressing potential fluctuations. Furthermore, it is preferable that the average primary particle size of the fluorine atom-containing resin particles is between 180 nm and 250 nm.

[0025] It is preferable that the fluorine atom-containing resin particles have an average roundness (average roundness) of 0.75 or higher, calculated from the area and circumference of primary particles measured from secondary electron images obtained by scanning electron microscopy.

[0026] To bring the measured values ​​of the average primary particle size and average roundness of the fluorine atom-containing resin particles contained in the surface layer of the electrophotographic photoreceptor of this disclosure within the above range, fluorine atom-containing resin particles can be used such that the average primary particle size and average roundness values ​​measured and calculated by the following method fall within the above range.

[0027] (Measurement method for average primary particle size and average roundness) In other words, in the embodiments of this disclosure, the average particle size and average roundness of the fluorine atom-containing resin particles to be incorporated into the surface layer of the electrophotographic photoreceptor were measured using a field emission scanning electron microscope (FE-SEM) as follows. Fluorine atom-containing resin particles were attached to a commercially available carbon conductive tape, and fluorine atom-containing resin particles not attached to the conductive tape were removed with compressed air, followed by platinum deposition. The deposited fluorine atom-containing resin particles were observed using a Hitachi High-Technologies Corporation FE-SEM (S-4700). The measurement conditions for the FE-SEM were as follows. Acceleration voltage: 2kV WD: 5mm Magnification: 20,000 times Pixel count: 1280 pixels vertically, 960 pixels horizontally (size of each pixel: 5nm) The Ferret diameter of 100 particles was determined from the obtained images using ImageJ (open-source software from the National Institutes of Health (NIH)), and the average value was calculated to determine the average particle size. Similarly, the area and perimeter were determined, the roundness was calculated using the following formula (II), and the average value was calculated and defined as the average roundness. Roundness = 4 × π × (area) ÷ (perimeter squared) Equation (II)

[0028] The fluorine atom-containing resin particles of this disclosure may be used alone or in combination of two or more types.

[0029] <Polymer A having the structural unit shown in formula (1)> The surface layer of the electrophotographic photoreceptor of this disclosure contains polymer A having a structural unit represented by the following formula (1). [ka]

[0030] In equation (1) above, R 11 R is a hydrogen atom or a methyl group. 12 R is a single bond or a methylene group. 12 When the atom is changed to an alkylene with 2 or more carbon atoms, the surface energy difference between the structural unit shown in formula (1) and the fluorine atom-containing resin particles becomes large, making it difficult for the atom to adhere sufficiently to the fluorine atom-containing resin particles, and resulting in insufficient dispersibility. 1 and Rf 2 Each of these is independently a perfluoroalkylene group having 1 to 3 carbon atoms or a perfluoroalkylidene group having 1 to 3 carbon atoms. Rf 3 Rf is a perfluoroalkyl group having 1 to 3 carbon atoms. 1 ~Rf 3 If the number of carbon atoms is increased to four or more, the accumulation of charge in the structural unit shown in formula (1) cannot be sufficiently suppressed, and potential fluctuations cannot be sufficiently suppressed when the electrophotographic photoreceptor is repeatedly used.

[0031] Furthermore, in formula (1) above, Rf 1 ~Rf 3 The total number of carbon atoms 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, Rf 1 ~Rf3 The total number of carbon atoms is more preferably 6 or more and 8 or less.

[0032] Examples of structural units represented by formula (1) used in this disclosure include those shown in Table 1 below.

[0033] [Table 1]

[0034] Of the polymer A contained in the surface layer of the electrophotographic photoreceptor of this disclosure, the content of the structural unit represented by formula (1) is preferably 5% to 95% (0.1% to 80% by mass) of the total structural units of polymer A, from the viewpoint of improving the dispersibility of fluorine atom-containing resin particles. Furthermore, it is more preferable that the structural unit represented by formula (1) is 50% to 95% (1% to 80% by mass) of the total structural units of polymer A. Furthermore, it is more preferable that the structural unit represented by formula (1) is 70% to 90% (4% to 66% by mass) of the total structural units of polymer A.

[0035] 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 this disclosure, is preferably 16,000 to 100,000, from the viewpoint of improving the dispersibility of fluorine atom-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 to 80,000.

[0036] The weight-average molecular weight of polymer A having the structural unit shown in formula (1) above can be measured and calculated by the following method.

[0037] (Weight-average molecular weight measurement by GPC) The weight-average molecular weight relating to this disclosure is measured by gel permeation chromatography (GPC) as follows. First, the sample is dissolved in tetrahydrofuran (THF) at room temperature for 24 hours. Then, the resulting solution is filtered through a solvent-resistant membrane filter, "Maeshori Disc" (manufactured by Tosoh Corporation), with a pore diameter of 0.2 μm, to obtain the 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 then used for measurement under the following conditions. • Equipment: HLC8120 GPC (Detector: RI) (Manufactured by Tosoh Corporation) • Columns: Shodex KF-801, 802, 803, 804, 805, 806, 807 (7 columns, manufactured by Showa Denko) • Eluent: Tetrahydrofuran (THF) ·Flow rate: 1.0ml / min Oven temperature: 40.0℃ • Sample injection volume: 0.10 ml For calculating the molecular weight of the sample, a molecular weight calibration curve prepared using standard polystyrene resin (for example, "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.

[0038] The content of polymer A having the structural unit represented by formula (1) in the surface layer relative to the fluorine atom-containing resin particles is preferably 2% by mass or more and 10% by mass or less, from the viewpoint of improving dispersibility and suppressing potential fluctuations. Furthermore, the content of polymer A having the structural unit represented by formula (1) in the surface layer relative to the fluorine atom-containing resin particles is more preferably 4% by mass or more and 8% by mass or less, from the viewpoint of improving dispersibility and suppressing potential fluctuations.

[0039] The polymer A is preferably a polymer having the structural unit represented by formula (1) and the structural unit represented by formula (2) below. [ka] (In formula (2), Y A1 This shows an unsubstituted alkylene group, Y B This refers to an unsubstituted alkylene group, a halogen-substituted alkylene group, a hydroxyl-substituted alkylene group, an ester bond (-COO-), an amide bond (-NHCO-), or a urethane bond (-NHCOO-), or a divalent linking group that can be derived by combining one or more of these groups or bonds with -O- or -S-, or a single bond. Z A This represents the structure represented by formula (2A), a cyano group, or a phenyl group. R 21 , R 22 Each of these independently represents either a hydrogen atom or a methyl group. m is an integer between 25 and 150 (inclusive). [ka] (In formula (2A), Z A1 This represents an alkyl group having 1 to 4 carbon atoms.

[0040] In formula (2), Y B If it shows an ester bond, -Y A1 -Y B -CH2- is -Y A1 -CO-O-CH2- and -Y A1 Either -O-CO-CH2- is acceptable, preferably -Y A1 It is -CO-O-CH2-. Also, in equation (2), Y B If it shows an amide bond, -Y A1 -Y B -CH2- is -Y A1 -NH-CO-CH2- and -Y A1 Either -CO-NH-CH2- is acceptable, preferably -Y A1 It is -NH-CO-CH2-. Also, in equation (2), Y B If it is a urethane bond, -Y A1 -Y B -CH2- is -YA1 -NH-CO-O-CH2- and -Y A1 Either -O-CO-NH-CH2- is acceptable, preferably -Y A1 It is -NH-CO-O-CH2-.

[0041] Also, -Y in equation (2) A1 -Y B - is, -Y A1 -(Y A2 ) b -(Y A3 ) c -(Y A4 ) d -(Y A5 ) e -(Y A6 ) f It is preferable to have the structure shown by -. (Y A1 This shows an unsubstituted alkylene group, Y A2 This represents a methylene group substituted with at least one selected from the group consisting of hydroxyl groups and halogen atoms. Y A3 This shows an unsubstituted alkylene group, Y A4 These represent ester bonds, amide bonds, or urethane bonds. Y A5 This shows an unsubstituted alkylene group, Y A6 This indicates an oxygen atom or a sulfur atom. b, c, d, e, and f each independently represent either 0 or 1.

[0042] It is preferable that polymer A has only the structural unit represented by formula (1) and the structural unit represented by formula (2) as structural units.

[0043] In equation (2) above [ka] It is preferable that the group is not an acidic group with a pKa of 3 or less.

[0044] In equation (2) above [ka] It is preferable that it is not -SO3H.

[0045] In polymer A having structural units represented by formula (1) and structural units represented by formula (2), the ratio of structural units represented by formula (1) to structural units represented by formula (2) is preferably 1:19 to 19:1 in molar ratio, more preferably 1:1 to 19:1, and even more preferably 7:3 to 9:1.

[0046] Examples of structural units represented by formula (2) include those having the structures shown in Table 2 below. [Table 2-1] [Table 2-2]

[0047] <Electrophotographic photoconductor> Figure 1 shows an example of the layer structure of the electrophotographic photoreceptor of this disclosure. In Figure 1, a base 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 composed of a laminated photosensitive layer having a charge generation layer and a charge transport layer, or it may be composed of a single-layer photosensitive layer containing a charge generation material and a charge transport material.

[0048] The surface layer of the electrophotographic photoreceptor of this disclosure contains fluorine atom-containing resin particles and polymer A having a structural unit represented by formula (1).

[0049] A method for manufacturing the electrophotographic photoreceptor according to this disclosure includes preparing coating solutions for each layer, applying the desired layers in order, and drying them. Examples of coating methods include immersion coating, spray coating, inkjet coating, roll coating, die coating, blade coating, curtain coating, wire bar coating, and ring coating. Among these, immersion coating is preferred from the viewpoint of efficiency and productivity.

[0050] The configuration of the electrophotographic photoreceptor described herein will be explained below. <Support> The support for the electrophotographic photoreceptor is preferably conductive (a conductive support). The support can take various shapes, such as cylindrical, belt-shaped, or sheet-shaped. A cylindrical support is preferred. The surface of the support may also be subjected to electrochemical treatments such as anodizing, blasting, or cutting. Suitable materials for the support include metal, resin, and glass. Examples of metals include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof. Among these, an aluminum support made of aluminum is preferred. Furthermore, it is preferable to impart conductivity to resins and glass by processing them, such as by mixing or coating them with conductive materials.

[0051] <Conductive layer> A conductive layer may be provided on the support. By providing a conductive layer, scratches and irregularities on the surface of the support can be concealed, and light reflection on the surface of the support can be controlled. The conductive layer preferably contains conductive particles and a resin.

[0052] Examples of materials for 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, and bismuth oxide. Examples of metals include aluminum, nickel, iron, nichrome, copper, zinc, and silver. Among these, it is preferable to use metal oxide particles as conductive particles, and it is more preferable to use titanium oxide particles, tin oxide particles, or zinc oxide particles. When using metal oxide particles as conductive particles, the surface 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 elements such as phosphorus or aluminum, or their oxides. Furthermore, the conductive particles may have a laminated structure comprising core material particles and a coating layer covering those particles. Examples of core material particles include titanium oxide particles, barium sulfate particles, and zinc oxide particles. Examples of coating layer particles include metal oxide particles such as tin oxide. Furthermore, when metal oxide particles are used as conductive particles, their volume-average particle size is preferably 1 nm or more and 500 nm or less, and more preferably 3 nm or more and 400 nm or less.

[0053] Examples of resins include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenolic resin, and alkyd resin. Furthermore, the conductive layer may further contain silicone oil, resin particles, a concealing agent such as titanium dioxide, etc.

[0054] A conductive layer can be formed by preparing a coating solution for a conductive layer containing the above-mentioned materials and solvents, forming this coating film on a support, and drying it. Examples of solvents used in the coating solution for a conductive layer 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 coating solution for a conductive layer include using a paint shaker, sand mill, ball mill, or liquid impaction type high-speed disperser.

[0055] 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.

[0056] <Underlayer> In this disclosure, an undercoat layer may be provided on the support or conductive layer. Providing an undercoat layer enhances the interlayer adhesion function and imparts a charge injection blocking function.

[0057] 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 polymerizable functional groups. Examples of resins include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, epoxy resin, melamine resin, polyurethane resin, phenolic resin, polyvinylphenol resin, alkyd resin, polyvinyl alcohol resin, polyethylene oxide resin, polypropylene oxide resin, polyamide resin, polyamic acid resin, polyimide resin, polyamide-imide resin, and cellulose resin. Polymerizable functional groups found in monomers possessing polymerizable functional groups include isocyanate groups, blocked isocyanate groups, methylol groups, alkylated methylol groups, epoxy groups, metal alkoxide groups, hydroxyl groups, amino groups, carboxyl groups, thiol groups, carboxylic acid anhydride groups, and carbon-carbon double bond groups.

[0058] Furthermore, the undercoat layer may further contain electron transport materials, metal oxide particles, metal particles, conductive polymers, etc., for the purpose of improving electrical properties. Among these, electron transport materials and metal oxide particles are preferred. Examples of electron transport materials include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienylidene compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, aryl halides, silole compounds, and boron-containing compounds. An electron transport material having polymerizable functional groups may be used as the electron transport material, and a base layer may be formed as a cured film by copolymerizing it with the above-mentioned monomers having polymerizable functional groups. Examples of metal oxide particles include 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 gold, silver, and aluminum. The metal oxide particles contained in the undercoat may be surface-treated using a surface treatment agent such as a silane coupling agent before use.

[0059] Common methods are used for surface treatment of metal oxide particles. Examples include dry and wet methods. The dry method involves adding an aqueous alcohol solution, an organic solvent solution, or an aqueous solution containing a surface treatment agent to metal oxide particles while stirring them in a high-speed mixer such as a Henschel mixer, then uniformly dispersing them and drying them. In the wet method, metal oxide particles and a surface treatment agent are stirred in a solvent or dispersed using a sand mill with glass beads or the like. 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.

[0060] The undercoat layer may further contain additives, such as known materials including metal particles like aluminum particles, conductive material particles like carbon black, charge transport materials, metal chelate compounds, and organometallic compounds.

[0061] The undercoat layer can be formed by preparing an undercoat coating solution containing the above-mentioned materials and solvents, forming this coating film on a support or conductive layer, and then drying and / or curing it.

[0062] Examples of solvents used in the coating liquid for the undercoat include organic solvents such as alcohols, sulfoxides, ketones, ethers, esters, aliphatic halogenated hydrocarbons, and aromatic compounds. In this disclosure, it is preferable to use alcohol-based or ketone-based solvents.

[0063] Dispersion methods for preparing coating liquids for the undercoat include methods using homogenizers, ultrasonic dispersers, ball mills, sand mills, roll mills, vibratory mills, attritors, and liquid impact type high-speed dispersers.

[0064] 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.

[0065] <Photosensitive layer> The photosensitive layers of electrophotographic photoreceptors are mainly classified into (1) multilayer photosensitive layers and (2) single-layer photosensitive layers. (1) A multilayer photosensitive layer is a photosensitive layer having a charge generating layer containing a charge generating material and a charge transport layer containing a charge transport material. (2) A single-layer photosensitive layer is a photosensitive layer containing both a charge generating material and a charge transport material.

[0066] (1) Stacked photosensitive layer The stacked photosensitive layer comprises a charge generation layer and a charge transport layer.

[0067] (1-1) Charge generation layer The charge generation layer preferably contains a charge generation material and a resin.

[0068] 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% to 85% by mass, and more preferably 60% to 80% by mass, relative to the total mass of the charge generating layer.

[0069] 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. Among these, polyvinyl butyral resin is more preferred.

[0070] Furthermore, the charge generation layer may contain additives such as antioxidants and ultraviolet absorbers. Specifically, examples include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, and benzophenone compounds.

[0071] The charge generation layer can be formed by preparing a coating solution for the charge generation layer containing the above-mentioned materials and solvents, forming this coating film on the undercoat layer, and drying it. Examples of solvents 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.

[0072] The thickness of the charge generation 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.

[0073] (1-2) Charge transport layer The charge transport layer preferably contains a charge transport material and a binder material. If the protective layer described later is not provided, the charge transport layer becomes the surface layer of the electrophotographic photoreceptor. In this case, the charge transport layer contains fluorine atom-containing resin particles, a binder material, and polymer A having the structural unit shown in formula (1).

[0074] Examples of charge transport materials include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, triarylamine compounds, and resins having groups derived from these substances. Among these, triarylamine compounds are preferred. The content of the charge transport material in the charge transport layer is preferably 25% by mass or more and 70% by mass or less, and more preferably 30% by mass or more and 55% by mass or less, based on the total mass of the charge transport layer.

[0075] Thermoplastic resin (hereinafter also referred to as "resin") is used as the binding material. Examples of thermoplastic resins include polyester resin, polycarbonate resin, acrylic resin, and polystyrene resin. Among these, polycarbonate resin and polyester resin are preferred. Polyarylate resin is particularly preferred among polyester resins. 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.

[0076] The content of fluorine atom-containing resin particles in the charge transport layer is preferably 5% by mass or more and 15% by mass or less. Furthermore, the content of fluorine atom-containing resin particles in the charge transport layer is preferably 7% by mass or more and 10% by mass or less.

[0077] Furthermore, the charge transport layer may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, and leveling agents. Specifically, 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.

[0078] The charge transport layer can be formed by preparing a coating solution for the charge transport layer containing the above-mentioned materials and solvents, forming this coating film on the charge generating 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. Among these solvents, ether-based solvents or aromatic hydrocarbon-based solvents are preferred.

[0079] The thickness of the charge transport layer is preferably 5 μm to 50 μm, more preferably 8 μm to 40 μm, and particularly preferably 10 μm to 30 μm.

[0080] (2) Single-layer photosensitive layer A single-layer photosensitive layer can be formed by preparing a coating solution for a photosensitive layer containing a charge generating substance, a charge transporting substance, a resin, and a solvent, forming this coating film on an undercoat layer, and drying it. The charge generating substance, charge transporting substance, and resin are the same as the examples of materials in "(1) Multilayer Photosensitive Layer" above.

[0081] <Protective layer> In this disclosure, a protective layer may be provided on the photosensitive layer. Providing a protective layer can improve durability.

[0082] 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 the structural unit represented by formula (1).

[0083] The protective layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group, which serves as a raw material for the binder. Examples of reactions include thermal polymerization, photopolymerization, and radiation polymerization. Examples of polymerizable functional groups in monomers having polymerizable functional groups include isocyanate groups, blocked isocyanate groups, methylol groups, alkylmethylol groups, epoxy groups, metal alkoxyl groups, hydroxyl groups, amino groups, carboxyl groups, thiol groups, carboxylic acid anhydride groups, and groups containing carbon-carbon double bonds. Examples of groups containing carbon-carbon double bonds include acryloyl groups and methacryloyl groups. Monomers having charge transport ability may be used as monomers having polymerizable functional groups.

[0084] Here, the cured product of a monomer having polymerizable functional groups serves as the binder for the protective layer. As monomers having polymerizable functional groups, it is preferable to use hole-transporting compounds having chain-polymerizable functional groups.

[0085] As a hole-transporting compound having a chain-polymerizable functional group, it is more preferable that the compound is represented by the following formula (CT-1) or (CT-2). [ka] (In the above formula (CT-1), Ar 11 ~Ar 13 Each of these is independently a substituted aryl group or an unsubstituted aryl group. The substituents that the substituted aryl group may have are alkyl groups having 1 to 6 carbon atoms, or monovalent functional groups represented by any of the following formulas (P-1) to (P-3). However, the compound represented by formula (CT-1) has at least one monovalent functional group represented by any of the following formulas (P-1) to (P-3). [ka] (In the above formula (CT-2), Ar 21 ~Ar 24These are, independently, a substituted aryl group or an unsubstituted aryl group, and Ar 25 This is a substituted aryl group or an unsubstituted aryl group. The substituents that the substituted aryl group may have are alkyl groups having 1 to 6 carbon atoms, or monovalent functional groups represented by the following formulas (P-1) to (P-3). The substituents that the substituted aryl group may have are alkyl groups having 1 to 6 carbon atoms, or monovalent functional groups represented by the following formulas (P-1) to (P-3). However, the compound represented by formula (CT-2) has at least one monovalent functional group represented by any of the following formulas (P-1) to (P-3). [ka] (In the above formula (P-1), Z 11 X is a single bond or an alkylene group having 1 to 6 carbon atoms. 11 (This is either a hydrogen atom or a methyl group.) [ka] (In the above formula (P-2), Z 21 (This refers to a single bond or an alkylene group having 1 to 6 carbon atoms.) [ka] (In the above formula (P-3), Z 31 (This refers to a single bond or an alkylene group having 1 to 6 carbon atoms.)

[0086] The content of fluorine atom-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 atom-containing resin particles in the protective layer is preferably 25% by mass or more and 35% by mass or less.

[0087] The protective layer preferably contains the compound represented by formula (3) below. Furthermore, when preparing the coating solution for the surface layer, the compound represented by formula (3) below is preferably a liquid compound, from the viewpoint of using it as a dispersion medium. [ka] In equation (3) above, R 31 R is an alkyl group or fluoroalkyl group. 32 R is a fluoroalkyl group. 31 It is preferable that it be a fluoroalkyl group.

[0088] Examples of compounds represented by formula (3) include methyl nonafluorobutyl ether, ethyl nonafluorobutyl ether, and 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. Among these, 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether is preferred from the viewpoint of improving dispersibility and suppressing potential fluctuations.

[0089] In the protective layer, it is preferable that the content of the compound represented by formula (3) is 1 ppm or more and 10 ppm or less, from the viewpoint of suppressing potential fluctuations. Furthermore, it is more preferable that the compound represented by formula (3) is 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether.

[0090] One method for measuring the content of the compound represented by formula (3) in the protective layer is, for example, GCMS analysis. As the measurement sample, the film mass is taken from the surface layer of the electrophotographic photoreceptor scraped off with a razor or the like. By analyzing this measurement sample with GCMS, the content of the compound represented by formula (3) contained in the surface layer can be measured. For example, the GCMS-QP2000 (manufactured by Shimadzu Corporation) can be used as the instrument for GCMS analysis. In the embodiment of this disclosure, after obtaining the measurement sample by the method described above, the content of the compound represented by formula (3) was measured using the GCMS instrument described above.

[0091] The protective layer may contain additives such as antioxidants, UV absorbers, plasticizers, and leveling agents. Specifically, these include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, and silicone oils.

[0092] The protective layer can be formed by preparing a protective coating solution containing the above-mentioned materials and solvents, forming this coating film on the photosensitive layer, and drying and / or curing it. Examples of solvents 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.

[0093] The thickness of the protective layer is preferably 0.5 μm to 10 μm, and more preferably 1 μm to 7 μm.

[0094] <Surface treatment of electrophotographic photoreceptors> In this disclosure, the surface of the electrophotographic photoreceptor may be processed. By processing the surface, the behavior of the cleaning means (cleaning blade) that comes into contact with the electrophotographic photoreceptor can be made more stable. Methods of surface processing include pressing a mold having protrusions onto the surface of the electrophotographic photoreceptor to transfer the shape, creating an uneven shape by mechanical polishing, or roughening the surface of the electrophotographic photoreceptor by impacting it with powder. By providing recesses or protrusions on the surface layer of the electrophotographic photoreceptor in this way, the behavior of the cleaning means that comes into contact with the electrophotographic photoreceptor can be made more stable.

[0095] The recesses or protrusions may be formed over the entire surface of the electrophotographic photoreceptor, or on a portion of the surface of the electrophotographic photoreceptor. If the recesses or protrusions are formed 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 contact area with the cleaning means (cleaning blade).

[0096] When forming a recess, a mold having a convex portion corresponding to the recess is pressed against the surface of the electrophotographic photoreceptor, and the shape is transferred, thereby forming a recess on the surface of the electrophotographic photoreceptor.

[0097] <Abrasive tools used for mechanical polishing> Mechanical polishing can be performed using known methods. Generally, a polishing tool is brought into contact with an electrophotographic photoreceptor, and either one or both of the tools are moved relative to each other to polish the surface of the electrophotographic photoreceptor. The polishing tool is a polishing member having a layer on a base material in which abrasive particles are dispersed in a binder resin.

[0098] Examples of abrasive particles include 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 particles is preferably 0.01 to 50 μm, and more preferably 1 to 15 μm. If the particle size of the abrasive particles is too small, the polishing power will be weak, and it will be difficult to increase the F / C ratio of the outermost surface of the electrophotographic photoreceptor. These abrasive particles can be used individually or in mixtures of two or more types. When mixing two or more types, the material and particle size may be different or the same.

[0099] As the binder resin for dispersing abrasive particles used in polishing tools, known thermoplastic resins, thermosetting resins, reactive resins, electron beam curing resins, ultraviolet curing resins, visible light curing resins, and antifungal resins can be used. 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.

[0100] The thickness of the layer formed by dispersing abrasive grains in the binder resin of the polishing tool is preferably 1 to 100 μm. If the thickness is too thick, unevenness in thickness is likely to occur, resulting in uneven surface roughness of the workpiece. On the other hand, if the thickness is too thin, the abrasive grains are more likely to fall off.

[0101] The shape of the base material of the polishing tool is not particularly limited. In the embodiments of this disclosure, a sheet-like base material was used to efficiently polish a cylindrical electrophotographic photoreceptor, but other shapes may also be used. (Hereafter, the polishing tool of this disclosure will also be referred to as a polishing sheet.) The material of the base material of the polishing tool is also not particularly limited. For example, the material of the sheet-like base material may be paper, woven fabric, nonwoven fabric, or plastic film.

[0102] The polishing tool can be obtained by coating a substrate with a paint mixture in which the above-mentioned abrasive grains, binder resin, and solvent capable of dissolving the binder resin are mixed and dispersed, and then drying the mixture.

[0103] <Polishing equipment> An example of the polishing apparatus for electrophotographic photoreceptors described herein is shown in Figure 2. Figure 2 shows an apparatus for polishing a cylindrical electrophotographic photoreceptor using a polishing sheet. In Figure 2, the polishing sheet 2-1 is wound around a hollow shaft 2-6, and a motor (not shown) is positioned so that tension is applied to the polishing sheet 2-1 in the opposite direction to the direction in which the polishing sheet 2-1 is fed to the shaft 2-6. The polishing sheet 2-1 is fed in the direction of the arrow, passes through guide rollers 2-2a and 2-2b to a backup roller 2-3, and after polishing, the polishing sheet 2-1 is wound onto 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 polishing sheet 2-1 against the workpiece (electrophotographic photoreceptor before polishing) 2-4. Since the polishing sheet 2-1 is often insulating, it is preferable to use a material that is grounded or conductive at the contact points of the polishing sheet 2-1.

[0104] The feed speed of the polishing sheet 2-1 is preferably in the range of 10 to 1000 mm / min. If the feed amount is small, the binder resin may adhere to the surface of the polishing sheet 2-1, and as a result, deep scratches may occur on the surface of the workpiece 2-4.

[0105] The workpiece 2-4 is placed at a position facing the backup roller 2-3 through the polishing sheet 2-1. From the viewpoint of improving the surface roughness uniformity of the workpiece 2-4, the backup roller 2-3 is preferably an elastic body. At this time, the workpiece 2-4 and the backup roller 2-3 are pressed against each other through the polishing sheet 2-1 at a desired set 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 direction in which the polishing sheet 2-1 is fed. Also, the rotation direction may be changed during polishing.

[0106] The pressing pressure of the backup roller 2-3 against the workpiece 2-4 is preferably 0.005 to 15 N / m, although it depends on the hardness of the backup roller 2-3 and the polishing time. 2 is preferred.

[0107] The surface roughness of the electrophotographic photoreceptor can be adjusted by appropriately selecting the feed speed of the polishing sheet 2-1, the pressing pressure of the backup roller 2-3, the abrasive grain type of the polishing sheet, the film thickness of the binder resin of the polishing sheet, the thickness of the substrate, etc.

[0108] <Measurement of the maximum height Rmax in JIS B0601 1982> The surface roughness of the electrophotographic photoreceptor can be measured by known means. For example, the following can be mentioned. Surface roughness meters such as the Surf Coater SE3500 type surface roughness measuring instrument manufactured by Kosaka Laboratory Ltd. Non-contact three-dimensional surface measuring machines such as the Micro Map 557N manufactured by Hishikawa System Co., Ltd. Microscopes capable of obtaining three-dimensional shapes such as the ultra-depth shape measuring microscopes VK-8550 and VK-9000 manufactured by Keyence Corporation.

[0109] In this disclosure, the maximum height Rmax specified in JIS B0601 1982, a Japanese Industrial Standard (JIS), is used as the polishing depth L (μm) among the surface roughness indicators. In this disclosure, Rmax is measured in advance within the range of a 5 mm square section of the electrophotographic photoreceptor to be cut out as a sample for X-ray photoelectron spectroscopy, as described later. Measurements are taken at three arbitrary locations within the 5 mm square range, and the average value is adopted as the polishing depth L (μm).

[0110] <Process cartridges, electrophotographic equipment> The electrophotographic photoreceptor of this disclosure may be a process cartridge or one of the components of an electrophotographic apparatus. The process cartridge is characterized by integrally supporting the electrophotographic photoreceptor described herein 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 attached to the main body of the electrophotographic apparatus. The electrophotographic apparatus is characterized by having the electrophotographic photoreceptor, charging means, exposure means, developing means, and transfer means described herein.

[0111] Figure 3 shows an example of a schematic configuration of an electrophotographic apparatus having a process cartridge equipped with an electrophotographic photoreceptor.

[0112] The cylindrical (drum-shaped) electrophotographic photoreceptor 201 is rotated at a predetermined peripheral speed (process speed) in the direction of the arrow around the axis 202. During the rotation process, the surface of the electrophotographic photoreceptor 201 is charged to a predetermined positive or negative potential by the charging means 203. Although 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 employed. Exposure light 204 is irradiated onto the surface of the charged electrophotographic photoreceptor 201 from an exposure means (not shown), and an electrostatic latent image corresponding to the target image information is formed. The exposure light 204 is light whose intensity is modulated in accordance with the time-series electrodigital image signal of the target image information, and is output from an image exposure means such as slit exposure or laser beam scanning exposure. The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 201 is developed (normal development or inverted development) with toner contained in the developing means 205, and a toner image is formed on the surface of the electrophotographic photoreceptor 201. The toner image formed on the surface of the electrophotographic photoreceptor 201 is transferred to the transfer material 207 by the transfer means 206. At this time, a bias voltage with the opposite polarity to the charge held by the toner is applied to the transfer means 206 from a bias power supply (not shown). If the transfer material 207 is paper, the transfer material 207 is taken out from the paper feed unit (not shown) and fed between the electrophotographic photoreceptor 201 and the transfer means 206 in synchronization with the rotation of the electrophotographic photoreceptor 201. The transfer material 207, onto which the toner image has been transferred from the electrophotographic photoreceptor 201, is separated from the surface of the electrophotographic photoreceptor 201 and transported to the fixing means 208, where it undergoes a toner image fixing process and is printed out as an image-forming product (print, copy) outside the electrophotographic device. The electrophotographic device may also have a cleaning means 209 for removing toner and other deposits remaining on the surface of the electrophotographic photoreceptor 201 after transfer. Alternatively, a so-called cleanerless system may be used, in which the above-mentioned adhering substances are removed by developing means or the like, without providing a separate cleaning means. A process cartridge can be formed by housing multiple components selected from the above-mentioned electrophotographic photoreceptor 201, charging means 203, developing means 205, and cleaning means 209 in a container and supporting them as a single unit. Furthermore, it can be configured to be detachably attached to the electrophotographic apparatus body.For example, the system may be configured as follows: At least one selected from the charging means 203, developing means 205, and cleaning means 209 is integrally supported with the electrophotographic photoreceptor 201 to form a cartridge. This can be made into a process cartridge 211 that can be attached to and detached from the electrophotographic apparatus body using guide means 212 such as rails on the electrophotographic apparatus body. The electrophotographic apparatus may have a static elimination mechanism that removes static electricity from the surface of the electrophotographic photoreceptor 201 with pre-exposure light 210 from a pre-exposure means (not shown). Guide means 212 such as rails may also be provided for attaching and detaching the process cartridge 11 to and from the electrophotographic apparatus body. The electrophotographic apparatus of this disclosure is characterized by having an electrophotographic photoreceptor 201, as well as a charging means 203, an exposure means, a developing means 205, and a transfer means 206.

[0113] Figure 4 shows a process cartridge configuration equipped with the electrophotographic photoreceptor of this disclosure, and Figure 5 shows an example of a schematic configuration of an electrophotographic apparatus having the process cartridge of Figure 4.

[0114] In Figure 4, the cylindrical electrophotographic photoreceptor 1 is driven to rotate at a predetermined peripheral speed in the direction of the arrow. The peripheral surface of the rotating electrophotographic photoreceptor 1 is uniformly charged to a predetermined positive or negative potential by the charging means 2. Next, the charged peripheral surface of the electrophotographic photoreceptor 1 receives exposure light (image exposure light) 3 output from an 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 the electrophotographic photoreceptor 1. The voltage applied to the charging means (charging roller, etc.) 2 may be either a voltage with an AC component superimposed on a DC component, or a voltage with only a DC component.

[0115] The electrostatic latent image formed on the circumferential surface of the electrophotographic photoreceptor 1 is developed by the toner contained in the developer of the developing means 4 to form a toner image. Next, the toner image formed and supported on the circumferential surface of the electrophotographic photoreceptor 1 is sequentially transferred to the transfer material (paper, intermediate transfer material, etc.) 6 by the transfer bias from the transfer means (transfer roller, etc.) 5. The transfer material 6 is fed in synchronization with the rotation of the electrophotographic photoreceptor 1.

[0116] After toner image transfer, the surface of the electrophotographic photoreceptor 1 is treated to remove static electricity by pre-exposure light 7 from a pre-exposure means (not shown), and then cleaned by a cleaning means 8 to remove any remaining toner. The electrophotographic photoreceptor 1 is then repeatedly used for image formation. The pre-exposure means may be performed before or after the cleaning process, and is not necessarily required.

[0117] The electrophotographic photoreceptor 1 may be mounted in an electrophotographic device such as a copier or a laser beam printer. Alternatively, a process cartridge 9 may be constructed by housing and supporting multiple components, such as the electrophotographic photoreceptor 1, charging means 2, developing means 4, and cleaning means 8, in a container, and making it detachable from the electrophotographic device body. In Figure 4, the electrophotographic photoreceptor 1, charging means 2, developing means 4, and cleaning means 8 are supported as a single unit in a process cartridge 9 that is detachable from the electrophotographic device body.

[0118] Next, an electrophotographic apparatus equipped with the electrophotographic photoreceptor of this disclosure will be described. Figure 5 shows an example of the configuration of the electrophotographic apparatus of this disclosure. Process cartridges 17 for yellow, 18 for magenta, 19 for cyan, and 20 for black, corresponding to yellow, magenta, cyan, and black respectively, are arranged side by side along the intermediate transfer body 10. The diameter and constituent materials of the electrophotographic photoreceptor, developer, charging method, and other means do not necessarily have to be the same for each color.

[0119] 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, the transfer paper 11 is fed from the paper tray 13 by the paper feed path 12 and is fed to the secondary transfer means 14 in time 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 the transfer bias from the secondary transfer means 14. The toner image transferred onto the transfer paper 11 is transported along the paper feed path 12, fixed onto the transfer paper by the fixing means 15, and then discharged from the paper discharge unit 16.

[0120] The electrophotographic photoreceptor of this disclosure can be used in laser beam printers, LED printers, copiers, facsimile machines, and multifunction devices thereof. [Examples]

[0121] The present disclosure will be described in further detail below using examples and comparative examples, but will not be limited thereto. In the following descriptions of examples, "parts" refers to mass unless otherwise specified.

[0122] <Synthesis of polymer A having the structural unit shown in formula (1)> The polymer A having the structural unit represented by formula (1) in this disclosure (hereinafter also referred to as "graft copolymer") was synthesized as follows. The acrylate compound and macromonomer compound used in the following synthesis example can be produced, for example, by referring to Japanese Patent Application Publication No. 2009-104145.

[0123] (Graft copolymer 1) 50 parts of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonoyl) acrylate (manufactured by 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, manufactured by 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, constant temperature bath, and thermometer at 20°C under a nitrogen atmosphere for 30 minutes. The reaction was then heated to 85-90°C and allowed to proceed 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 and 2-propanol in a ratio of 1:5, and dried at a temperature of 80°C under reduced pressure of 1325 Pa or less for 3 hours to obtain graft copolymer 1. [ka]

[0124] (Graft copolymer 2) Graft copolymer 2 was obtained in the same manner as graft copolymer 1, except that 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanyl)acrylate was replaced with 1H,1H-perfluoro(2,5-dimethyl-4,6-dioxanonanyl)acrylate.

[0125] (Graft copolymer 3) Graft copolymer 3 was obtained in the same manner as graft copolymer 1, except that 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanyl)acrylate was replaced with 40 parts of 1H,1H-perfluoro(4,7-dioxanonanyl)acrylate.

[0126] (Graft copolymer 4) Graft copolymer 4 was obtained in the same manner as graft copolymer 1, except that 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanyl)acrylate was replaced with 55 parts of 1H,1H-perfluoro(3,6-dimethyl-4,7-dioxadecanoyl)acrylate.

[0127] (Graft copolymer 5) Graft copolymer 5 was obtained in the same manner as graft copolymer 1, except that 2.5 parts of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanyl)acrylate and 570 parts of the macromonomer represented by formula (A) were replaced.

[0128] (Graft copolymer 6) Graft copolymer 6 was obtained in the same manner as graft copolymer 1, except that 12.5 parts of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanyl)acrylate and 450 parts of the macromonomer represented by formula (A) were replaced.

[0129] (Graft copolymer 7) Graft copolymer 7 was obtained in the same manner as graft copolymer 1, except that 25 parts of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanyl)acrylate and 300 parts of the macromonomer represented by formula (A) were replaced.

[0130] (Graft copolymer 8) Graft copolymer 8 was obtained in the same manner as graft copolymer 1, except that 35 parts of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanyl)acrylate and 180 parts of the macromonomer represented by formula (A) were replaced.

[0131] (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-dioxanonanyl)acrylate were added.

[0132] (Graft copolymer 10) Graft copolymer 10 was obtained in the same manner as graft copolymer 1, except that 0.819 parts of 1,1'-azobis(1-acetoxy-1-phenylethane) were added.

[0133] (Graft copolymer 11) Graft copolymer 11 was obtained in the same manner as graft copolymer 1, except that 0.728 parts of 1,1'-azobis(1-acetoxy-1-phenylethane) were added.

[0134] (Graft copolymer 12) Graft copolymer 12 was obtained in the same manner as graft copolymer 1, except that 0.164 parts of 1,1'-azobis(1-acetoxy-1-phenylethane) were added.

[0135] (Graft copolymer 13) Graft copolymer 13 was obtained in the same manner as graft copolymer 1, except that 0.131 parts of 1,1'-azobis(1-acetoxy-1-phenylethane) were added.

[0136] (Graft copolymer 14) Graft copolymer 14 was obtained in the same manner as graft copolymer 1, except that 0.874 parts of 1,1'-azobis(1-acetoxy-1-phenylethane) were added.

[0137] (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) were added.

[0138] (Graft copolymer 16) Graft copolymer 16 was obtained in the same manner as graft copolymer 1, except that 20 parts of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanyl)acrylate and 360 parts of the macromonomer represented by formula (A) were replaced.

[0139] (Graft copolymer 17) Graft copolymer 17 was obtained in the same manner as graft copolymer 1, except that 50 parts of 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanyl)acrylate and 30 parts of the macromonomer represented by formula (A) above were replaced.

[0140] (Graft copolymer 18) Graft copolymer 18 was obtained in the same manner as graft copolymer 1, except that 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanyl)acrylate was replaced with 25 parts of 1H,1H-perfluoro(3,5-dioxahexanoyl)acrylate.

[0141] (Graft copolymer 19) Graft copolymer 19 was obtained in the same manner as graft copolymer 1, except that 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanyl)acrylate was replaced with 35 parts of 1H,1H-perfluoro(3,6-dioxaoctanoyl)acrylate.

[0142] (Graft copolymer 20) Graft copolymer 20 was obtained in the same manner as graft copolymer 1, except that 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanyl)acrylate was replaced with 1H,1H-perfluoro(4,7-dioxaundecanoyl)acrylate.

[0143] (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-dioxanonanyl)acrylate was replaced with 1H,1H,2H,2H-perfluoro(3,6-dimethyl-4,7-dioxadecanoyl)acrylate.

[0144] (Graft copolymer 22) Graft copolymer 22 was obtained in the same manner as graft copolymer 1, except that 1H,1H-perfluoro(2,5-dimethyl-3,6-dioxanonanyl)acrylate was replaced with 1H,1H,2H,2H-perfluoro(4,7-dioxaundecanoyl)acrylate.

[0145] The obtained graft copolymers 1-22 were subjected to GPC measurement using the method described above, and their weight-average molecular weight was calculated. The results are shown in Table 3.

[0146] [Table 3]

[0147] <Fabrication of electrophotographic photoreceptors> [Example 1-1] (Support 1) As a support (conductive support), a cylindrical aluminum cylinder (JIS-A3003, aluminum alloy, outer diameter 30.6 mm, length 370 mm, wall thickness 1 mm) that had been machined was used. Ultrasonic cleaning was performed in a cleaning solution containing detergent (product name: Chemicol CT, manufactured by Tokiwa Chemical Co., Ltd.) in pure water, followed by rinsing off the cleaning solution, and then further ultrasonic cleaning in pure water to degrease it, and this was used as support 1.

[0148] (Bottom layer 1) Zinc oxide particles (specific surface area: 19 m²) 2 / g, powder resistance: 4.7×10 6 100 parts of (Ω·cm) were mixed with 500 parts of toluene and stirred. 0.8 parts of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) were added, and the mixture was stirred for 6 hours. Subsequently, the toluene was removed by distillation under reduced pressure, and the mixture was heated and dried at 130°C for 6 hours to obtain surface-treated zinc oxide particles A.

[0149] Next, 15 parts of butyral (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) and 15 parts of blocked isocyanate (trade name: Duranate TPA-B80E, non-volatile 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 for 3 hours at a 23±3°C atmosphere using a sand mill apparatus with glass beads with a diameter of 0.8 mm. After dispersion treatment, 0.01 parts of silicone oil (product name: SH28PA, manufactured by Toray Dow Corning Co., Ltd. (formerly Toray Dow Corning Silicone Co., Ltd.)) and 5.6 parts of cross-linked polymethyl methacrylate (PMMA) particles (product name: Techpolymer SSX-103, manufactured by Sekisui Chemical Co., Ltd., average primary particle size: 3 μm) were added and stirred to prepare a coating solution for the undercoat layer. The obtained undercoating solution for the undercoat layer was applied to the support 1 by immersion to form a coating film, and the coating film was dried at 160°C for 30 minutes to form an undercoat layer 1 with a thickness of 18 μm.

[0150] (Charge generation layer 1) Four parts of hydroxygallium phthalocyanine crystals (charge-generating material) in a crystalline form having strong peaks at 7.4° and 28.1° of the Bragg angle 2θ±0.2° in CuKα characteristic X-ray diffraction, and 0.04 parts of the compound represented by the following formula (E) were added to a solution prepared by dissolving 2 parts of polyvinyl butyral (trade name: S-Rec BX-1, manufactured by Sekisui Chemical Co., Ltd.) in 100 parts of cyclohexanone. Subsequently, the mixture was dispersed for 1 hour in a sand mill using 1 mm diameter glass beads under an atmosphere of 23±3°C. After dispersion, 100 parts of ethyl acetate were added to prepare a coating solution for the charge-generating layer. This charge generation layer coating solution was applied to the undercoat layer 1 by immersion, and the resulting coating film was dried at 90°C for 10 minutes to form a charge generation layer 1 with a thickness of 0.15 μm. [ka]

[0151] (Charge transport layer 1) A coating solution for the charge transport layer was prepared by dissolving 60 parts of the compound represented by formula (F) below, 30 parts of the compound represented by formula (G) below, 10 parts of the compound represented by formula (H) below, 100 parts of bisphenol Z type polycarbonate resin (product name: Yupiron Z400, manufactured by Mitsubishi Engineering Plastics Corporation), and 0.2 parts of polycarbonate having the unit represented by formula (I) below (viscosity-average molecular weight Mv: 20000) in a mixed solvent of 272 parts o-xylene, 256 parts methyl benzoate, and 272 parts dimethoxymethane. This charge transport layer coating solution was applied to the above-mentioned charge generating layer 1 by immersion 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 with a thickness of 18 μm. [ka] [ka] [ka] [ka] (In equation (I), 0.95 and 0.05 are the molar ratios (copolymerization ratios) of the two units.)

[0152] (protective layer) A dispersant solution was prepared by dissolving 2.20 parts of the aforementioned 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. 40 parts of polytetrafluoroethylene resin particles (average primary particle size 210 nm, average roundness 0.85) were added to the obtained dispersant solution. Then, 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.

[0153] To the obtained polytetrafluoroethylene resin particle dispersion, 75.4 parts of a hole-transporting compound represented by formula (B) below, 21.9 parts of a compound represented by formula (C) below, and 100 parts of 1-propanol were added. Subsequently, the mixture was filtered using a polyflon filter (product name: PF-040, manufactured by Advantec Toyo Co., Ltd.) to prepare a polytetrafluoroethylene resin particle dispersion (coating solution for protective layer). [ka] [ka]

[0154] This protective coating solution was applied to the charge transport layer by immersion to form a coating film, and the resulting film was dried at 40°C for 5 minutes. After drying, the coating film was irradiated with an electron beam for 1.6 seconds under conditions of an accelerating voltage of 70kV and an absorbed dose of 15kGy in a nitrogen atmosphere. Subsequently, the coating film was heat-treated for 15 seconds under conditions of a nitrogen atmosphere to reach a temperature of 135°C. The oxygen concentration from electron beam irradiation to the 15-second heat treatment was 15ppm. Next, the coating film was allowed to cool naturally in air until its temperature reached 25°C, and then heat-treated for 1 hour to reach a temperature of 105°C to form a surface layer (protective layer) with a thickness of 5μm.

[0155] The content of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether in the surface layer was 5 ppm.

[0156] In this way, an electrophotographic photoreceptor having a support and a surface layer before surface polishing was fabricated.

[0157] <Surface treatment of electrophotographic photoreceptors> (Polishing of the electrophotographic photoreceptor before surface polishing) The surface of the electrophotographic photoreceptor was polished before surface shaping was formed. Polishing was performed using the polishing apparatus shown in Figure 2 under the following conditions. Abrasive sheet feed speed: 400 mm / min Rotation speed of the electrophotographic photoreceptor: 450 rpm Pressing the electrophotographic photoreceptor onto the backup roller; 3.5 mm Rotation direction of the polishing sheet and electrophotographic photoreceptor; with Backup roller; outer diameter 100mm, Asker C hardness 25 Polishing sheet A, which is attached to the polishing device, was made by mixing the abrasive grains used in GC3000 and GC2000, manufactured by Riken Corundum Co., Ltd. GC3000 (Abrasive sheet surface roughness Ra0.83μm) GC2000 (Abrasive sheet surface roughness Ra1.45μm) Abrasive sheet A (Surface roughness of abrasive sheet Ra 1.12 μm) The polishing time using polishing sheet A was set to 20 seconds.

[0158] (Measurement of polishing depth L (μm)) The maximum height Rmax of the electrophotographic photoreceptor after polishing was measured according to 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. Measurements were taken 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 photoreceptor after surface polishing was 0.75 μm. Furthermore, in Examples 1-2 to 1-25 described later, the polishing depth L of the electrophotographic photoreceptors that underwent surface processing was all 0.75 μm. (Measurement conditions) Pixel: R2μm Stylus: 0.7mN diamond needle Filter: 2CR Cutoff value: 0.08mm Measurement length: 2.5mm Feed speed: 0.1mm

[0159] [Examples 1-2 to 1-13, 1-22 to 1-27, Comparative Examples 1-1 to 1-3] In the formation of the protective layer, an electrophotographic photoreceptor was produced in the same manner as in Example 1-1, except that the graft copolymer 1 was changed to the graft copolymers 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.

[0160] 〔Examples 1-14 to 1-15, 1-20 to 1-21〕 In the formation of the protective layer, an electrophotographic photoreceptor was produced in the same manner as in Example 1-1, except that the graft copolymer 1 was changed to the parts 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.

[0161] 〔Examples 1-16 to 1-19〕 In the formation of the protective layer, an electrophotographic photoreceptor was produced in the same manner as in Example 1-1, except that the polytetrafluoroethylene resin particles having the average primary particle diameter and average roundness 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.

[0162]

Table 4

[0163] 〔Example 2-1〕 (Support 2) As the support (conductive support), a cylindrical aluminum cylinder (JIS-A3003, aluminum alloy, outer diameter 30 mm, length 357.5 mm, wall thickness 0.7 mm) obtained by cutting was used. It was ultrasonically cleaned in a cleaning liquid containing a detergent (trade name: Chemicol CT, manufactured by Tokiwa Chemical Co., Ltd.) in pure water, and then the cleaning liquid was rinsed off. Subsequently, it was ultrasonically cleaned in pure water for degreasing treatment, and this was used as Support 2.

[0164] (Undercoat layer 2) Zinc oxide particles (average particle diameter: 70 nm, specific surface area value: 15 m 260 parts of / g) were stirred and mixed with 500 parts of tetrahydrofuran, and 0.75 parts of a silane coupling agent (chemical name: N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, trade name: KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.) were added thereto, followed by stirring 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.

[0165] Subsequently, 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: Sumidule 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 using a sand mill with glass beads having a diameter of 1 mm for 5 hours. After the dispersion treatment, 0.008 parts of dioctyltin dilaurate and 6.5 parts of silicone resin particles (Tospearl 145, manufactured by GE Toshiba Silicone Co., Ltd.) were added and stirred to prepare a coating solution for the undercoat layer. The obtained coating solution for the undercoat layer was dip-coated on 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 having a film thickness of 15 μm.

[0166] (Charge generation layer 2) Next, 15 parts of chlorogallium phthalocyanine crystals having strong diffraction peaks at at least 7.4 °, 16.6 °, 25.5 ° and 28.3 ° of the Bragg angle (2θ ± 0.2 °) 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 using a sand mill with glass beads having a diameter of 1 mm for 4 hours to prepare a coating solution for the charge generation layer. This coating solution for the charge generation layer was dip-coated on the undercoat layer 2, and the obtained coating film was dried at 150 °C for 5 minutes to form a charge generation layer 2 having a film thickness of 0.2 μm.

[0167] (Charge transport layer) Next, 10 parts of polytetrafluoroethylene resin particles (average primary particle size: 210 nm, average roundness: 0.85), 0.50 part of the above graft copolymer 1, and 24 parts of tetrahydrofuran were stirred and mixed while maintaining the liquid temperature at 20°C for 48 hours to obtain a formulation liquid 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 part of 2,6-di-t-butyl-4-methylphenol as an antioxidant were mixed, and 250 parts of tetrahydrofuran was mixed and dissolved therein to obtain a formulation liquid B. After adding the formulation liquid A to the formulation liquid B and stirring and mixing them, the mixture was passed through a high-pressure disperser (trade name: Microfluidizer M-110EH, manufactured by Microfluidics Corporation, USA) to obtain a dispersion liquid.

[0168] Thereafter, fluorine-modified silicone oil (trade name: FL-100, manufactured by Shin-Etsu Silicone Co., Ltd.) was added to the dispersion liquid so as to be 5 ppm, and the mixture was filtered with a polytetrafluoroethylene filter (trade name: PF-040, manufactured by Advantec Toyo Co., Ltd.) to prepare a coating liquid for the charge transport layer. This coating liquid for the charge transport layer was dip-coated on the charge generation layer 2 to form a coating film, and the obtained coating film was dried at 150°C for 25 minutes to form a charge transport layer having a film thickness of 30 μm. In this manner, an electrophotographic photoreceptor was produced.

[0169] 〔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 copolymers shown in Table 5 in the formation of the charge transport layer.

[0170] 〔Examples 2-14 to 2-15, 2-20 to 2-21〕 An electrophotographic photoreceptor was produced in the same manner as in Example 2-1, except that the graft copolymer 1 was changed to the parts by mass shown in Table 5 in the formation of the charge transport layer.

[0171] [Examples 2-16 to 2-19] An electrophotographic photoreceptor was fabricated in the same manner as in Example 2-1, except that the polytetrafluoroethylene resin particles used in the formation of the charge transport layer were changed to polytetrafluoroethylene resin particles with the average primary particle size and average roundness shown in Table 5.

[0172] [Table 5]

[0173] <Evaluation of electrophotographic photoconductors> 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.

[0174] [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 in a Canon imagePRESS C800 copier (product name) and evaluated. For further details, the evaluation apparatus was set up in an environment with a temperature of 23°C and a relative humidity of 50%RH. The fabricated electrophotographic photoreceptor was mounted onto a magenta process cartridge, which was then placed in the magenta process cartridge station for evaluation.

[0175] [Evaluation device 1-2] The electrophotographic photoreceptors prepared in Examples 1-1 to 1-27 and Comparative Examples 1-1 to 1-3 were installed in a modified Canon imagePRESS C800 copier (product name) and evaluated. The charging means of the modified copier is a method of applying a voltage obtained by superimposing an AC voltage on a DC voltage to a roller-type contact charging member (charging roller), and the exposure means is a laser image exposure method (wavelength 680 nm). For further details, the evaluation apparatus was set up in an environment with a temperature of 23°C and a relative humidity of 50%RH. The fabricated electrophotographic photoreceptor was mounted onto a magenta process cartridge, which was then placed in the magenta process cartridge station for evaluation. The charging conditions were adjusted so that the charging potential was -800V and the exposure potential was -300V, by adjusting the charging potential and the exposure amount of the exposure means.

[0176] The surface potential of the electrophotographic photoreceptor was measured by removing the developing cartridge from the evaluation apparatus described above, inserting a potential measuring device into its place, and then measuring the potential. The potential measuring device consists of a potential measuring probe (product name: model6000B-8, manufactured by Trek Japan Co., Ltd.) placed at the developing position of the developing cartridge. The position of the potential measuring probe relative to the electrophotographic photoreceptor was set to the center in the direction of the electrograph line of the electrophotographic photoreceptor, with a gap of 3 mm from the surface of the electrophotographic photoreceptor. Furthermore, the potential of the central part of the electrophotographic photoreceptor was measured using a surface potential meter (product name: model344, manufactured by Trek Japan Co., Ltd.).

[0177] [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 Canon imageRUNNER iR-ADV C5051 copier and evaluated. For further details, the evaluation apparatus was set up in an environment with a temperature of 23°C and a relative humidity of 50%RH. The fabricated electrophotographic photoreceptor was mounted on a cyan process cartridge, and then the cartridge was placed in the cyan process cartridge station for evaluation.

[0178] [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 Canon imageRUNNER iR-ADV C5051 copier (the charging method involves applying a voltage obtained by superimposing an AC voltage on a DC voltage to a roller-type contact charging element (charging roller), and the exposure method is a laser image exposure method (wavelength 780 nm)) and evaluated. For further details, the evaluation apparatus was set up in an environment with a temperature of 23°C and a relative humidity of 50%RH. The fabricated electrophotographic photoreceptor was mounted on a cyan process cartridge, and then the cartridge was placed in the cyan process cartridge station for evaluation. The charging conditions were adjusted so that the charging potential was -700V and the exposure potential was -200V, by adjusting the charging potential and the exposure amount of the exposure means. The surface potential of the electrophotographic photoreceptor was measured by removing the developing cartridge from the evaluation apparatus described above and inserting a potential measuring device into it. The potential measuring device consisted of a potential measuring probe (product name: model6000B-8, manufactured by Trek Japan Co., Ltd.) placed at the developing position of the developing cartridge. The position of the potential measuring probe relative to the electrophotographic photoreceptor was set to the center in the direction of the electrograph line of the electrophotographic photoreceptor, with a gap of 3 mm from the surface of the electrophotographic photoreceptor. Furthermore, the potential of the central part of the electrophotographic photoreceptor was measured using a surface potential meter (product name: model344, manufactured by Trek Japan Co., Ltd.).

[0179] (Initial image evaluation) Image evaluation was performed using evaluation apparatus 1-1 and evaluation apparatus 2-1 described above. Using A4 size gloss paper, a completely white image was output, and the number of image defects due to dispersion defects, i.e., black dots, contained in the area of ​​one circumference of the electrophotographic photoreceptor in the output image was visually evaluated according to the following evaluation ranks. The area of ​​one circumference of the electrophotographic photoreceptor is a rectangular area with a vertical dimension of 297 mm (the length of the long side of the A4 paper) and a horizontal dimension of 94.2 mm (the circumference of one circumference of the electrophotographic photoreceptor). In this disclosure, ranks A, B, C, and D represent levels where the effects of this disclosure are obtained, with rank A being judged to be an excellent level. On the other hand, rank E was judged to be a level where the effects of this disclosure are not obtained. A: There are no black spots at all. B: There are 1 to 3 black spots less than 1.5 mm in diameter, and no black spots larger than 1.5 mm in diameter. C: One to three black dots less than 1.5 mm in diameter, AND one to two black dots 1.5 mm or larger in diameter. D: There are 4 to 5 black spots with a diameter of less than 1.5 mm, AND 2 or fewer black spots with a diameter of 1.5 mm or more. E: Six or more black spots less than 1.5 mm in diameter, or three or more black spots 1.5 mm or larger in diameter. The results of this evaluation are shown in Table 6.

[0180] (Evaluation of Potential Variation during Repeated Use) The evaluation of potential variation during repeated use was carried out using the above-described evaluation device 1-2 and evaluation device 2-2. A cartridge equipped with the electrophotographic photoreceptor was attached to the evaluation device, and the photoreceptor was repeatedly used for 10,000 sheets of paper passing. At the station where the electrophotographic photoreceptor was installed, a character image with a printing rate of 1% in monochrome was formed repeatedly 10,000 times on A4-sized plain paper. 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 value of potential variation (ΔVd). Also, the initial bright potential was compared with the bright potential after 10,000 sheets of repeated image formation, and this was taken as the value of potential variation (ΔVl). After 10,000 sheets of paper passing were completed, it was left for 5 minutes, the developing cartridge was replaced with the potential measuring device, and the bright 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 taken as the dark potential variation amount (ΔVd = |Vdb| - |Vda|). Also, the difference between the bright potential after repeated use and the initial bright potential (Vla) was taken as the bright potential variation amount (ΔVl = |Vlb| - |Vla|). In the evaluation using the evaluation device 1-2, the bright potential variation amounts during repeated use of 100,000 sheets, 300,000 sheets, and 500,000 sheets were further measured. Also, in the evaluation using the evaluation device 2-2, the bright potential variation amount during repeated use of 100,000 sheets was further measured. In the present disclosure, when the change in the bright potential was within 40 V, it was determined that the effect of the present disclosure was obtained, and among them, when the change in the bright potential was within 15 V, it was determined that it was a particularly excellent level. In this way, the evaluation results are shown in Table 6.

[0181] [ [Table 6] [Explanation of Reference Numerals]

[0182] 101 Support 102 Undercoat Layer 103 Charge generation layer 104 Charge transport layer 105 Surface layer (protective layer) 201 Electrophotographic photoreceptor 202 axis 203 Charging means 204 Exposure light 205 Developing means 206 Transfer means 207 Transfer material 208 Fixing means 209 Cleaning methods 210 Pre-exposure light 211 Process Cartridge 212 Guidance methods 1. Electrophotographic photoreceptor 2. Charging means 3. Exposure light (image exposure light) 4. Developing means 5. Transfer means 6 Transfer material 7. Pre-exposure light 8. Cleaning methods 9 Process Cartridges 10 Intermediate Transfer 11 Transfer paper 12 Paper feed path 13 Paper feed tray 14. Secondary transfer means 15 Fixing means 16 Paper output section 17 Process cartridge for yellow color 18 Magenta Process Cartridges 19 Cyan process cartridge 20 Process cartridges for black color

Claims

1. 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.

1. An electrophotographic photoreceptor comprising: 【Chemistry 1】 (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. 【Chemistry 2】 (In formula (2), Y A1 represents an unsubstituted alkylene group; Y B represents an unsubstituted alkylene group, an alkylene group substituted with a halogen atom, an alkylene group substituted with a hydroxyl 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 between 25 and 150. 【Chemistry 3】 (In formula (2A), Z A1 represents an alkyl group having 1 to 4 carbon atoms.)

2. 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 based on 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.

1. An electrophotographic photoreceptor comprising: 【Chemistry 4】 (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.

3. 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 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.

1. An electrophotographic photoreceptor comprising: 【Chemistry 5】 (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.

4. 3. The electrophotographic photoreceptor according to claim 1, wherein 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 all structural units in the polymer A.

5. 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.

6. 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): 【Chemistry 6】 (In formula (2), Y Ａ１ represents an unsubstituted alkylene group, Y Ｂ represents an unsubstituted alkylene group, an alkylene group substituted with a halogen atom, an alkylene group substituted with a hydroxyl 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 represents a hydrogen atom or a methyl group, m is an integer between 25 and 150. 【Chemistry 7】 (In formula (2A), Z Ａ１ represents an alkyl group having 1 to 4 carbon atoms.

7. The electrophotographic photoreceptor according to claim 1, wherein the total number of carbon atoms in Rf 1 to Rf 3 in formula (1) is 6 or more and 9 or less.

8. An electrophotographic photoreceptor described in 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 mass % or more and 80 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.

10. 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 any one of claims 1, 6, 7 and 10, wherein the ratio of the structural unit represented by the formula (1) to the structural unit represented by the formula (2) in the polymer A is from 1:19 to 19:1 in terms of a molar ratio.

12. 12. The electrophotographic photoreceptor according to claim 1, wherein the content of the fluorine atom-containing resin particles in the surface layer is from 5% by mass to 40% by mass with respect to the total mass of the surface layer.

13. The electrophotographic photoreceptor according to any one of claims 1 to 12, 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): 【Chemistry 8】 (In the above formula (CT-1), Ar １１ ~Ar １３ each independently represents 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 formulas (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 formulas (P-1) to (P-3). 【Chemistry 9】 (In the above formula (CT-2), Ar ２１ ~Ar ２４ each independently represents a substituted aryl group or an unsubstituted aryl group; Ar ２５ represents a substituted arylene group or an unsubstituted arylene group, a substituent which 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), a substituent which 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 formula (CT-2) has at least one monovalent functional group represented by any of the following formulas (P-1) to (P-3). 【Chemistry 10】 (In the formula (P-1), Z １１ represents a single bond or an alkylene group having 1 to 6 carbon atoms; X １１ represents a hydrogen atom or a methyl group.) 【Chemistry 11】 (In the formula (P-2), Z ２１ represents a single bond or an alkylene group having 1 to 6 carbon atoms. 【Chemistry 12】 (In the formula (P-3), Z ３１ represents a single bond or an alkylene group having 1 to 6 carbon atoms.

15. 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 from 20% by mass to 40% by mass with respect to the total mass of the surface layer.

16. 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): 【Chemistry 13】 (In formula (3), R ３１ represents an alkyl group or a fluoroalkyl group; R ３２ represents a fluoroalkyl group.

17. 17. A process cartridge which 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 a main body of an electrophotographic apparatus.

18. 17. An electrophotographic apparatus comprising: the electrophotographic photoreceptor according to claim 1; a charging unit, an exposing unit, a developing unit, and a transferring unit.

19. A method for producing an electrophotographic photoreceptor having a surface layer, comprising the steps of: The manufacturing method comprises: A step of preparing a coating liquid for a surface layer, the 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, forming a coating film of the surface layer coating liquid and drying and / or curing the coating film to form the surface layer; have 2. A method for producing an electrophotographic photoreceptor comprising the steps of: 【Chemistry 14】 (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. 【Chemistry 15】 (In formula (2), Y A1 represents an unsubstituted alkylene group; Y B represents an unsubstituted alkylene group, an alkylene group substituted with a halogen atom, an alkylene group substituted with a hydroxyl 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 between 25 and 150. 【Chemistry 16】 (In formula (2A), Z A1 represents an alkyl group having 1 to 4 carbon atoms.)

20. A method for producing an electrophotographic photoreceptor having a surface layer, comprising the steps of: The manufacturing method comprises: A step of preparing a coating liquid for a surface layer, the 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; forming a coating film of the surface layer coating liquid and drying and / or curing the coating film to form the surface layer; having 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; 2. A method for producing an electrophotographic photoreceptor comprising the steps of: 【Chemistry 17】 (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.

21. A method for producing an electrophotographic photoreceptor having a surface layer, comprising the steps of: The manufacturing method comprises: A step of preparing a coating liquid for a surface layer, the 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; 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 with respect to all structural units in the polymer A; 2. A method for producing an electrophotographic photoreceptor comprising the steps of: 【Chemistry 18】 (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.

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