Electrophotographic photoreceptor, process cartridge, and electrophotographic apparatus

Abstract

To provide an electrophotographic photoreceptor that has excellent surface wear resistance and can also maintain excellent electric characteristics while preventing the occurrence of ghost even under high-temperature and high-humidity environment.SOLUTION: An electrophotographic photoreceptor includes a support, a photosensitive layer, and a surface layer in this order. The surface layer contains: a cured product of a composition containing a specific charge transporting compound; and polytetrafluoroethylene particles. Primary particles of the polytetrafluoroethylene particles have a number average particle size of 110 nm or more and 130 nm or less. In the surface layer, a content of the polytetrafluoroethylene particles relative to a total mass of the surface layer is 16 mass% or more.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to an electrophotographic photoreceptor, a process cartridge having the electrophotographic photoreceptor, and an electrophotographic apparatus having the electrophotographic photoreceptor. [Background technology]

[0002] The electrophotographic photoreceptor mounted on an electrophotographic device includes an organic electrophotographic photoreceptor (hereinafter referred to as "electrophotographic photoreceptor") that contains an organic photoconductive material (charge generating material). In recent years, there has been a demand for a longer life for electrophotographic photoreceptors and an increase in the number of prints that can be output per unit time from electrophotographic devices, and accordingly, there is a demand for the surface layer of the electrophotographic photoreceptor to have excellent abrasion resistance while maintaining good electrical properties.

[0003] Patent Document 1 discloses a technology in which the surface layer of an electrophotographic photoreceptor is made of a crosslinked product of a specific compound, and the surface layer of the electrophotographic photoreceptor maintains good electrical properties while improving the wear resistance of the electrophotographic photoreceptor. As the specific compound constituting the crosslinked product, a charge transporting compound having a hydroxyalkyl group and an alkoxyalkyl group as polymerizable functional groups is disclosed.

[0004] On the other hand, as the wear resistance of the electrophotographic photoreceptor increases, the removal of the chemically deteriorated surface layer caused by the rubbing with the cleaning blade (hereinafter also referred to as "blade") on the surface of the electrophotographic photoreceptor becomes difficult. As a result, the frictional force between the blade and the surface of the electrophotographic photoreceptor increases over a long period of use, so it is more necessary to suppress the increase in the frictional force.

[0005] In order to reduce the frictional force on the surface of an electrophotographic photoreceptor, for example, Patent Document 2 discloses a technique in which polytetrafluoroethylene particles are contained in the surface layer. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] JP 2011-8117 A [Patent Document 2] Japanese Patent Application Publication No. 06-332219 Summary of the Invention [Problem to be solved by the invention]

[0007] As a result of the study by the present inventors, by incorporating the polytetrafluoroethylene particles described in Patent Document 2 into the surface layer of the electrophotographic photoreceptor described in Patent Document 1, the surface of the electrophotographic photoreceptor has wear resistance and the frictional force with the blade can be reduced. However, on the other hand, in a high-temperature and high-humidity environment, ghosts (positive ghosts in which only the parts of the output image that were irradiated with light during the previous rotation have high density, or negative ghosts in which only the parts of the output image that were irradiated with light during the previous rotation have low density) may occur. In addition, in a high-temperature and high-humidity environment, electrical properties may deteriorate.

[0008] Therefore, an object of the present invention is to provide an electrophotographic photoreceptor which has excellent surface abrasion resistance, and which can maintain good electrical characteristics while suppressing the occurrence of ghosts even in a high-temperature and high-humidity environment. Another object of the present invention is to provide a process cartridge having the electrophotographic photoreceptor having the above characteristics, and an electrophotographic apparatus having the electrophotographic photoreceptor having the above characteristics. [Means for solving the problem]

[0009] The above object is achieved by the present invention. That is, an electrophotographic photoreceptor according to one embodiment of the present invention is an electrophotographic photoreceptor having a support, a photosensitive layer, and a surface layer in this order, characterized in that the surface layer contains a cured product of a composition containing a charge transporting compound represented by the following formula (1), a charge transporting compound represented by the following formula (2), and polytetrafluoroethylene particles, the number average particle diameter of the primary particles of the polytetrafluoroethylene particles is 110 nm or more and 130 nm or less, the content ratio of the charge transporting compound represented by the following formula (1) to the charge transporting compound represented by the following formula (2) in the composition is within a range of 40:60 to 60:40, and the content ratio of the polytetrafluoroethylene particles in the surface layer to the total mass of the surface layer is 16 mass% or more. [ka] (In formula (1), Ar 11 ~Ar 13 Each of Ar independently represents a phenyl group which may have a substituent. 11 ~Ar 13 The substituent that the phenyl group represented by the formula (I) may have is a group selected from the group consisting of a methyl group, an ethyl group, a methoxy group, a hydroxyalkyl group, and an alkoxyalkyl group, and when a plurality of substituents are present, the plurality of substituents may be the same or different from each other. 11 ~Ar 13 Two of the phenyl groups represented by the formula (1) have a hydroxyalkyl group or an alkoxyalkyl group as a substituent, and the total number of the hydroxyalkyl groups and the alkoxyalkyl groups contained in the charge transporting compound represented by the formula (1) is 2. [ka] (In formula (2), Ar 21 ~Ar 24 each independently represents a phenyl group having a substituent, Ar 25 ~Ar 26 Each of Ar independently represents a phenylene group which may have a substituent. 21 ~Ar 24The phenyl group represented by the formula (I) has one hydroxyalkyl or alkoxyalkyl group as a substituent, and Ar 21 ~Ar 24 The phenyl group represented by the formula (I) may further have one or more substituents selected from the group consisting of a methyl group, an ethyl group, and a methoxy group. 25 ~Ar 26 The substituent that the phenylene group represented by the formula (I) may have is a group selected from the group consisting of a methyl group and an ethyl group.

[0010] Furthermore, a process cartridge according to another aspect of the present invention is characterized in that it integrally supports the above-mentioned electrophotographic photosensitive member and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, and is detachably attachable to the main body of the electrophotographic apparatus.

[0011] Further, an electrophotographic apparatus according to still another aspect of the present invention comprises the above electrophotographic photosensitive member, a charging means, an exposing means, a developing means and a transferring means. Effect of the Invention

[0012] According to the present invention, it is possible to provide an electrophotographic photoreceptor having excellent surface abrasion resistance, capable of suppressing the occurrence of ghosts even in a high-temperature and high-humidity environment, and capable of maintaining good electrical properties. Also, according to the present invention, it is possible to provide a process cartridge having the electrophotographic photoreceptor, and an electrophotographic apparatus having the electrophotographic photoreceptor. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a diagram showing an example of a layer structure of an electrophotographic photoreceptor. [Diagram 2] FIG. 1 is a diagram showing an example of a schematic configuration of an electrophotographic apparatus provided with a process cartridge having an electrophotographic photosensitive member. [Diagram 3]FIG. 13 is a schematic diagram showing an image for evaluating ghosts used in the examples, where (a) is a diagram showing the overall configuration of the image for evaluating ghosts, and (b) is a diagram showing a one-dot knight pattern image in the image for evaluating ghosts. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The present invention will be described in detail below with reference to preferred embodiments. The electrophotographic photoreceptor according to the present invention has a support, a photosensitive layer, and a surface layer in this order, wherein the surface layer contains a cured product of a composition containing a charge transport compound represented by the following formula (1), a charge transport compound represented by the following formula (2), and polytetrafluoroethylene particles, the number average particle diameter of primary particles of the polytetrafluoroethylene particles is 110 nm or more and 130 nm or less, the content ratio of the charge transport compound represented by the following formula (1) to the charge transport compound represented by the following formula (2) in the composition is within a range of 40:60 to 60:40, and the content ratio of the polytetrafluoroethylene particles in the surface layer to the total mass of the surface layer is 16 mass% or more. [ka] (In formula (1), Ar 11 ~Ar 13 Each of Ar independently represents a phenyl group which may have a substituent. 11 ~Ar 13 The substituent that the phenyl group represented by the formula (I) may have is a group selected from the group consisting of a methyl group, an ethyl group, a methoxy group, a hydroxyalkyl group, and an alkoxyalkyl group, and when a plurality of substituents are present, the plurality of substituents may be the same or different from each other. 11 ~Ar 13 Two of the phenyl groups represented by the formula (1) have a hydroxyalkyl group or an alkoxyalkyl group as a substituent, and the total number of the hydroxyalkyl groups and the alkoxyalkyl groups contained in the charge transporting compound represented by the formula (1) is 2. [ka] (In formula (2), Ar 21 ~Ar 24 each independently represents a phenyl group having a substituent, Ar 25 ~Ar 26 Each of Ar independently represents a phenylene group which may have a substituent. 21 ~Ar 24 The phenyl group represented by the formula (I) has one hydroxyalkyl or alkoxyalkyl group as a substituent, and Ar 21 ~Ar 24 The phenyl group represented by the formula (I) may further have one or more substituents selected from the group consisting of a methyl group, an ethyl group, and a methoxy group. 25 ~Ar 26 The substituent that the phenylene group represented by the formula (I) may have is a group selected from the group consisting of a methyl group and an ethyl group.

[0015] The present inventors speculate as follows why the electrophotographic photoreceptor having the specific configuration according to the present invention can suppress image defects and maintain good electrical characteristics without impairing mechanical durability.

[0016] In the cured film of the charge transport compound having hydroxyalkyl group and alkoxyalkyl group as polymerizable functional group, unreacted hydroxyalkyl group and alkoxyalkyl group are present. Therefore, in a high temperature and high humidity environment, moisture is adsorbed to the highly polar hydroxyalkyl group and alkoxymethyl group, and the charge tends to remain in the photosensitive layer. This makes ghosts more likely to occur and the electrical properties tend to deteriorate.

[0017] In the present invention, the surface layer of the electrophotographic photoreceptor has a cured product of a composition containing a charge transporting compound having two polymerizable functional groups and a charge transporting compound having four polymerizable functional groups in a specific ratio. It is considered that the cured product has gaps large enough to accommodate particles of 110 to 130 nm.

[0018] The hydrophobic polytetrafluoroethylene particles have a particle size that allows them to easily reside in the gaps between the molecules of the cured material, which is believed to prevent moisture from being adsorbed onto the hydroxyalkyl and alkoxyalkyl groups, and thus suppress the retention of electric charges in the photosensitive layer.

[0019] From the above, it is presumed that the electrophotographic photoreceptor according to the present invention not only has excellent abrasion resistance, but also exhibits the effect of suppressing the occurrence of ghosts and the deterioration of electrical properties.

[0020] The combined content of the charge transport compound represented by formula (1) and the charge transport compound represented by formula (2) in the surface layer is preferably 50% by mass or more and 84% by mass or less based on the total mass of the surface layer.

[0021] The charge transport compound represented by formula (2) is Ar 21 ~Ar 24 It is more preferable that each of the formulas is a charge transporting compound having one hydroxymethyl group as a substituent.

[0022] Specific examples of the charge transporting compound represented by formula (1) are listed below, but the invention is not limited thereto. [ka]

[0023] As the charge transporting compound represented by formula (1), among the compounds represented by formulas (1-1) to (1-14), the compounds represented by formulas (1-1) to (1-4) and (1-9) to (1-12) are particularly preferred.

[0024] Specific examples of the charge transporting compound represented by formula (2) are listed below, but the invention is not limited thereto. [ka]

[0025] As the charge transporting compound represented by formula (2), among the compounds represented by formulae (2-1) to (2-16), the compounds represented by formulae (2-1) to (2-3) are particularly preferred.

[0026] In the surface layer of the electrophotographic photoreceptor, the proportion of polytetrafluoroethylene particles having a primary particle diameter of 140 nm or more is preferably 10% or less by number relative to the total number of polytetrafluoroethylene particles, which increases the proportion of polytetrafluoroethylene particles present in the gaps of the cured material in the surface layer, thereby making it possible to obtain a higher effect of suppressing the retention of electric charges.

[0027] The content of polytetrafluoroethylene particles in the surface layer of the electrophotographic photoreceptor is preferably 16% by mass or more and 45% by mass or less, based on the total mass of the surface layer, and more preferably 20% by mass or more and 40% by mass or less, in order to suppress electrical characteristics.

[0028] It is preferable for the polytetrafluoroethylene particles to have a crystallinity of 70% or more and 75% or less in order to suppress charge retention. The reason for this is presumed to be as follows. If the crystallinity of the polytetrafluoroethylene particles is too high, the dispersant is less likely to be adsorbed, and the dispersibility of the polytetrafluoroethylene particles is reduced. Therefore, the polytetrafluoroethylene particles are less likely to enter the gaps between the molecules of the cured product. This makes it easier for moisture to be adsorbed to the hydroxyalkyl group and alkoxyalkyl group of the charge transport compound in a high-temperature, high-humidity environment, and it is thought that charge retention is more likely to occur. On the other hand, if the crystallinity of the polytetrafluoroethylene particles is too low, the gaps in the polytetrafluoroethylene particles increase, making it easier for moisture to be adsorbed in the particles, and charge retention is more likely to occur. Due to this balance, it is preferable for the crystallinity of the polytetrafluoroethylene particles to be 70% or more and 75% or less in order to suppress charge retention.

[0029] In the present invention, the cured product of the composition containing the charge transporting compound represented by formula (1), the charge transporting compound represented by formula (2), and polytetrafluoroethylene particles means a product obtained by curing the composition. The composition may have elements other than the charge transporting compound represented by formula (1), the charge transporting compound represented by formula (2), and polytetrafluoroethylene particles.

[0030] Next, the configuration of the electrophotographic photoreceptor according to the present invention will be described. [Electrophotographic photoreceptor] The electrophotographic photoreceptor has a support, a photosensitive layer, and a surface layer in this order. FIG. 1 is a diagram showing an example of a layer structure of an electrophotographic photoreceptor. In FIG. 1, the electrophotographic photoreceptor has a support 111 , an undercoat layer 112 , a charge generating layer 113 , a charge transport layer 114 , and a surface layer 115 . The surface layer of the electrophotographic photoreceptor contains a cured product of a composition containing a charge transport compound represented by formula (1), a charge transport compound represented by formula (2), and polytetrafluoroethylene particles, as described above.

[0031] As a method for manufacturing an electrophotographic photoreceptor, a method of preparing the coating liquid for each layer described later, coating the coating liquid on a support in the desired layer order, and drying the coating liquid can be mentioned. In this case, as a method for coating the coating liquid, dip coating, spray coating, inkjet coating, roll coating, die coating, blade coating, curtain coating, wire bar coating, ring coating, spinner coating, bead coating, beam coating, etc. can be mentioned. Among these, dip coating is preferred from the viewpoint of efficiency and productivity.

[0032] The support and each layer will be described below. <Support> In the present invention, the electrophotographic photoreceptor has a support. The support is preferably one having electrical conductivity (conductive support). The shape of the support may be cylindrical, belt-like, sheet-like, or the like. Among them, a cylindrical support is preferable. In addition, the surface of the support may be subjected to electrochemical treatment such as anodization, blasting, cutting, or the like. The material of the support is preferably metal, resin, glass, or the like. Examples of the metal include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof. Among them, an aluminum support using aluminum is preferable. Furthermore, the resin or glass may be made conductive by a process such as mixing or coating with a conductive material.

[0033] <Conductive layer> In the present invention, a conductive layer may be provided on the support. By providing the 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.

[0034] Examples of materials for the conductive particles include metal oxides, metals, and carbon black. Examples of metal oxides include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, bismuth oxide, etc. Examples of metals include aluminum, nickel, iron, nichrome, copper, zinc, silver, etc. Among these, it is preferable to use metal oxides as the conductive particles, and it is particularly preferable to use titanium oxide, tin oxide, or zinc oxide. When a metal oxide is used as the conductive particles, the surface of the metal oxide may be treated with a silane coupling agent or the like, or the metal oxide may be doped with an element such as phosphorus or aluminum or an oxide thereof. The conductive particles may have a laminated structure having a core particle and a coating layer that covers the core particle. Examples of the core particle include titanium oxide, barium sulfate, zinc oxide, etc. Examples of the coating layer include metal oxides such as tin oxide. When a metal oxide is used as the conductive particles, the 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.

[0035] Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, and alkyd resin. The conductive layer may further contain silicone oil, resin particles, a masking agent such as titanium oxide, and the like.

[0036] The thickness of the conductive layer is preferably from 1 μm to 50 μm, and particularly preferably from 3 μm to 40 μm.

[0037] The conductive layer can be formed by preparing a conductive layer coating solution containing the above-mentioned materials and solvent, forming a coating film of this, and drying it. Examples of the solvent 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. Examples of the dispersion method for dispersing the conductive particles in the conductive layer coating solution include a method using a paint shaker, a sand mill, a ball mill, and a liquid collision type high-speed disperser.

[0038] <Undercoat layer> In the present invention, an undercoat layer may be provided on the support or the conductive layer. By providing an undercoat layer, the adhesion between layers can be improved and a charge injection blocking function can be imparted. The undercoat layer preferably contains a resin. Alternatively, the undercoat layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group.

[0039] Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinyl phenol resin, alkyd resin, polyvinyl alcohol resin, polyethylene oxide resin, polypropylene oxide resin, polyamide resin, polyamic acid resin, polyimide resin, polyamideimide resin, and cellulose resin.

[0040] Examples of the polymerizable functional group contained in the monomer having a polymerizable functional group include an isocyanate group, a blocked isocyanate group, a methylol group, an alkylated methylol group, an epoxy group, a metal alkoxide group, a hydroxyl group, an amino group, a carboxyl group, a thiol group, a carboxylic anhydride group, and a carbon-carbon double bond group.

[0041] For the purpose of improving electrical properties, the undercoat layer may further contain an electron transporting material, a metal oxide, a metal, a conductive polymer, etc. Among these, it is preferable to use an electron transporting material or a metal oxide. Examples of the electron transport substance include a quinone compound, an imide compound, a benzimidazole compound, a cyclopentadienylidene compound, a fluorenone compound, a xanthone compound, a benzophenone compound, a cyanovinyl compound, an aryl halide compound, a silole compound, a boron-containing compound, etc. An electron transport substance having a polymerizable functional group may be used as the electron transport substance, and the undercoat layer may be formed as a cured film by copolymerizing the electron transport substance with the monomer having the polymerizable functional group. Examples of metal oxides include indium tin oxide, tin oxide, indium oxide, titanium oxide, zinc oxide, aluminum oxide, silicon dioxide, etc. Examples of metals include gold, silver, aluminum, etc. The undercoat layer may further contain an additive.

[0042] The thickness of the undercoat layer is preferably from 0.1 μm to 50 μm, more preferably from 0.2 μm to 40 μm, and particularly preferably from 0.3 μm to 30 μm.

[0043] The undercoat layer can be formed by preparing a coating solution for the undercoat layer containing the above-mentioned materials and solvent, forming the coating film on the support or the conductive layer, and drying and / or curing the coating film. Examples of the solvent used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0044] <Photosensitive layer> The photosensitive layer of an electrophotographic photoreceptor is mainly classified into (1) a multi-layer type photosensitive layer and (2) a single-layer type photosensitive layer. (1) The multi-layer type photosensitive layer has a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. (2) The single-layer type photosensitive layer has a photosensitive layer containing both a charge generation material and a charge transport material.

[0045] (1) Laminated photosensitive layer The laminated type photosensitive layer has a charge generating layer and a charge transport layer.

[0046] (1-1) Charge generation layer The charge generating layer preferably contains a charge generating material and a resin.

[0047] Examples of the charge generating material 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 from 40% by mass to 85% by mass, and more preferably from 60% by mass to 80% by mass, based on the total mass of the charge generating layer.

[0048] Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, polyvinyl butyral resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinyl alcohol resin, cellulose resin, polystyrene resin, polyvinyl acetate resin, polyvinyl chloride resin, etc. Among these, polyvinyl butyral resin is more preferable.

[0049] The charge generating layer may further contain additives such as an antioxidant and an ultraviolet absorbing agent, etc. Specific examples of such additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, and benzophenone compounds.

[0050] The thickness of the charge generating layer is preferably from 0.1 μm to 1 μm, and more preferably from 0.15 μm to 0.4 μm.

[0051] The charge generating layer can be formed by preparing a coating solution for the charge generating layer containing the above-mentioned materials and solvent, forming the coating film on, for example, the above-mentioned undercoat layer, and drying it. Examples of the solvent 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.

[0052] (1-2) Charge transport layer The charge transport layer preferably contains a charge transport material and a resin.

[0053] Examples of the charge transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these materials. The content of the charge transport material in the charge transport layer is preferably from 25% by weight to 70% by weight, and more preferably from 30% by weight to 55% by weight, based on the total weight of the charge transport layer.

[0054] Examples of the resin include polyester resin, polycarbonate resin, acrylic resin, polystyrene resin, etc. Among these, polycarbonate resin and polyester resin are preferable. As the polyester resin, polyarylate resin is particularly preferable. The content ratio (mass ratio) of the charge transport material to the resin is preferably from 4:10 to 20:10, and more preferably from 5:10 to 12:10.

[0055] The charge transport layer may also contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slipping agents, and abrasion resistance improvers. Specific examples of such additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles.

[0056] The thickness of the charge transport layer is preferably from 5 μm to 50 μm, more preferably from 8 μm to 40 μm, and particularly preferably from 10 μm to 30 μm.

[0057] The charge transport layer can be formed by preparing a coating solution for the charge transport layer containing the above-mentioned materials and solvent, forming the coating film on, for example, the above-mentioned charge generating layer, and drying it. Examples of the solvent 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.

[0058] (2) Single-layer photosensitive layer The single-layer type photosensitive layer can be formed by preparing a coating solution for the photosensitive layer containing a charge generating material, a charge transporting material, a resin and a solvent, forming the coating film on, for example, the above-mentioned undercoat layer, and drying it. The charge generating material, the charge transporting material and the resin are the same as the examples of materials in the above "(1) Multi-layer type photosensitive layer".

[0059] <Surface layer> In the present invention, in the case of a laminated type photosensitive layer, a surface layer may be provided on the charge transport layer of the laminated type photosensitive layer, and in the case of a single-layer type photosensitive layer, a surface layer may be provided on the photosensitive layer. The configuration of the surface layer of the electrophotographic photoreceptor according to the present invention is as described above.

[0060] In addition to the above-mentioned components, the surface layer may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slippage imparting agents, abrasion resistance improvers, etc. Specific examples of the additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, boron nitride particles, etc. The content of the additive in the surface layer is preferably 0.02% by mass or more and 30% by mass or less based on the total mass of the surface layer.

[0061] Furthermore, the charge transporting compound may contain a charge transporting compound other than the charge transporting compound represented by formula (1) and the charge transporting compound represented by formula (2).The charge transporting compound may be a polycyclic aromatic compound, a heterocyclic compound, a hydrazone compound, a styryl compound, an enamine compound, a benzidine compound, a triarylamine compound, or a resin having a group derived from these substances.Among these, triarylamine compounds and benzidine compounds are preferred.

[0062] Furthermore, the surface layer preferably contains a copolymer containing a fluoroalkyl group as a dispersant for the tetrafluoroethylene particles. In particular, the dispersant for the tetrafluoroethylene particles is preferably a polymer having a structural unit represented by the following formula (3) and a structural unit represented by the following formula (4). [ka] (R in Equation (3) 31 R represents a hydrogen atom or a methyl group. 32 R represents an alkylene group. 33represents a perfluoroalkyl group having 4 to 7 carbon atoms. [ka] (In formula (4), R 41 represents a hydrogen atom or a methyl group; Y represents a divalent organic group having at least the structure represented by the following formula (5); Z has a structure represented by the following formula (6). [ka] (In formula (5), Y 1 and Y 2 each independently represents an alkylene group which may have a substituent; Y 2 is bonded to the oxygen atom in formula (4), and the sulfur atom is bonded to the structure shown in formula (6) below. [ka] (R in Equation (6) 61 R represents a hydrogen atom or a methyl group. 62 represents a hydrogen atom or an alkyl group.

[0063] In the structural unit represented by formula (3), R 32 Examples of the alkylene group represented by the formula (I) include linear alkylene groups such as methylene, ethylene, propylene, butylene, pentylene, and hexylene, and branched alkylene groups such as isopropylene and isobutylene. 32 The alkylene group represented by the formula: is preferably a methylene group, an ethylene group, a propylene group, or a butylene group.

[0064] In addition, in the structural unit represented by formula (5), Y 1 and Y 2 Examples of the alkylene group represented by the formula (I) include a methylene group, an ethylene group, a propylene group, a butylene group, a pentylene group, and a hexylene group. 1 and Y 2The alkylene group represented by Y is preferably a methylene group, an ethylene group, or a propylene group. 1 and Y 2 Examples of the substituent that the alkylene group represented by the formula (I) may have include an alkyl group, an alkoxyl group, a hydroxyl group, and an aryl group. 1 and Y 2 Examples of the alkyl group as a substituent that may be possessed by the alkylene group represented by the formula: include a methyl group, an ethyl group, a propyl group, and a butyl group. Among these, a methyl group and an ethyl group are preferred. 1 and Y 2 Examples of the alkoxyl group as a substituent that may be possessed by the alkylene group represented by the formula: include a methoxy group, an ethoxy group, and a propoxyl group. Among these, a methoxy group is preferred. 1 and Y 2 Examples of the aryl group as a substituent that may be possessed by the alkylene group represented by the formula: include a phenyl group and a naphthyl group. Among these, a phenyl group is preferable. In particular, 1 and Y 2 The substituents which the alkylene group represented by the formula (I) may have are preferably a methyl group and a hydroxy group.

[0065] In addition, in the structural unit represented by formula (6), R 62 Examples of the alkyl group represented by R include a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, a hexyl group, a heptyl group, an octyl group, and a nonyl group. 62 The alkyl group represented by the formula (I) is preferably a hydrogen atom, a methyl group, an ethyl group, a propyl group, a butyl group, a pentyl group, or a hexyl group.

[0066] The copolymerization form in the polymer having the structural unit represented by formula (3) and the structural unit represented by formula (4) is arbitrary, but it is preferably a comb-type graft structure having the structural unit represented by formula (4) in the side chain. The fluoroalkyl moiety of the structural unit represented by formula (3) in the dispersant has high affinity with polytetrafluoroethylene particles, and adsorbs to the polytetrafluoroethylene particles to disperse them. Furthermore, the structural unit represented by formula (4) in the dispersant is in the side chain of the comb-type graft structure, which increases the steric repulsion between the polytetrafluoroethylene particles to which the dispersant is adsorbed. This can further increase the dispersibility of the polytetrafluoroethylene particles.

[0067] The copolymerization ratio of the structural unit represented by formula (3) to the structural unit represented by formula (4) (structural unit represented by formula (3):structural unit represented by formula (4)) is preferably within a range of 99:1 to 20:80 in terms of molar ratio, and more preferably within a range of 95:5 to 30:70.

[0068] The weight average molecular weight of the polymer having the structural unit represented by formula (3) and the structural unit represented by formula (4) is preferably 50,000 or more and 150,000 or less, and more preferably 80,000 or more and 130,000 or less.

[0069] Specific examples of the structural unit represented by formula (3) are listed below, but the present invention is not limited thereto. [ka]

[0070] Specific examples of the structural unit represented by formula (4) are given below, but the present invention is not limited thereto. [ka] [ka]

[0071] The content of the dispersant for the polytetrafluoroethylene particles in the surface layer is preferably 2.0% by mass or more and 15.0% by mass or less, more preferably 3.0% by mass or more and 10.0% by mass or less, based on the total mass of the polytetrafluoroethylene particles.

[0072] Furthermore, the surface layer may contain a guanamine compound having a hydroxymethyl group or an alkoxymethyl group, a melamine compound, or a homopolymer thereof. In particular, the surface layer preferably contains a guanamine compound represented by the following formula (A), a melamine compound represented by the following formula (B), or a homopolymer thereof. [ka] (In formula (A), R 101 ~R 104 represents a hydrogen atom, a hydroxymethyl group, or an alkoxymethyl group; R 101 ~R 104 At least one of R is a hydroxymethyl group or an alkoxymethyl group. 105 represents an alkyl group which may have a substituent, a phenyl group which may have a substituent, or a cycloalkyl group which may have a substituent. In formula (A), R 105 The substituents which the alkyl group, phenyl group and cycloalkyl group represented by the formula (I) may have include an alkyl group and an alkoxy group. [ka] (In formula (B), R 201 ~R 206 represents a hydrogen atom, a hydroxymethyl group, an alkoxymethyl group, or an alkoxy group; R 201 ~R 206 At least one of is a hydroxymethyl group, an alkoxymethyl group, or an alkoxy group.

[0073] The surface layer contains a guanamine compound, a melamine compound, or a homopolymer thereof having a hydroxymethyl group or an alkoxymethyl group, thereby improving the film strength. Furthermore, these compounds contain nitrogen atoms that contribute to electron transport, thereby improving the electron transport in the surface layer. The content of the guanamine compound and / or melamine compound, or a homopolymer thereof in the surface layer is preferably 0.5% by mass or more and 20% by mass or less based on the total mass of the surface layer.

[0074] Commercially available guanamine compounds include Super Beckamine L-148-55, Super Beckamine 13-535, Super Beckamine L-145-60, and Super Beckamine TD-126 (all manufactured by DIC Corporation), Nikalac BL-60, and Nikalac BX-4000 (all manufactured by Sanwa Chemical Co., Ltd.).

[0075] Commercially available melamine compounds include Super Melami No. 90 (manufactured by NOF Corporation), Super Beckamin TD-139-60 (manufactured by DIC Corporation), U-Ban 2020 (manufactured by Mitsui Chemicals, Inc.), Sumitex Resin M-3 (manufactured by Sumitomo Chemical Co., Ltd.), and Nikalac MW-30 (manufactured by Sanwa Chemical Co., Ltd.).

[0076] The thickness of the surface layer is preferably 0.5 μm or more and 10.0 μm or less, and more preferably 1.0 μm or more and 7.0 μm or less.

[0077] The surface layer can be formed by preparing a coating solution for the surface layer containing the materials and solvent described above, forming this coating film on the photosensitive layer, and drying and / or curing it.

[0078] When forming a cured film, a curing catalyst can be contained in the surface layer coating liquid.As the curing catalyst, aliphatic carboxylic acids such as acetic acid, chloroacetic acid, trichloroacetic acid, trifluoroacetic acid, oxalic acid, maleic acid, malonic acid, lactic acid, etc., aromatic carboxylic acids such as benzoic acid, phthalic acid, terephthalic acid, trimellitic acid, etc., aliphatic and aromatic sulfonic acids such as methanesulfonic acid, dodecylsulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, naphthalenesulfonic acid, etc., and their derivatives are preferably used.

[0079] Examples of the solvent used in the coating liquid include alcohol-based solvents, ketone-based solvents, ether-based solvents, sulfoxide-based solvents, ester-based solvents, aliphatic halogenated hydrocarbon-based solvents, and aromatic hydrocarbon-based solvents.

[0080] The coating of the surface layer coating liquid can be cured by heat, ultraviolet light, and / or electron beams. When irradiating with electron beams, examples of accelerators include scanning type, electrocurtain type, broad beam type, pulse type, laminar type, etc. The acceleration voltage of the electron beam is preferably 120 kV or less from the viewpoint of suppressing deterioration of material properties caused by the electron beam without impairing polymerization efficiency. In addition, the electron beam absorbed dose on the surface of the coating film of the surface layer coating solution is preferably 1 kGy or more and 50 kGy or less, more preferably 5 kGy or more and 10 kGy or less.

[0081] In addition, when the composition is cured (polymerized) using an electron beam, it is preferable to irradiate the composition with the electron beam in an inert gas atmosphere and then heat the composition in an inert gas atmosphere, from the viewpoint of suppressing the polymerization inhibition action caused by oxygen. Examples of the inert gas include nitrogen, argon, and helium.

[0082] After irradiation with ultraviolet rays or electron beams, the electrophotographic photoreceptor is preferably heated to 100° C. or higher and 140° C. or lower, thereby obtaining a surface layer that has even higher durability and suppresses image defects.

[0083] The surface of the surface layer may be subjected to surface treatment using an abrasive sheet, a shape transfer member, glass beads, zirconia beads, etc. Also, unevenness may be formed on the surface using a constituent material of the coating liquid.

[0084] [Process cartridges, electrophotographic devices] The process cartridge according to the present invention integrally supports the electrophotographic photosensitive member described above and at least one means selected from the group consisting of charging means, developing means, and cleaning means, and is detachably attachable to the main body of the electrophotographic apparatus. The electrophotographic apparatus according to the present invention comprises the electrophotographic photosensitive member, charging means, exposure means, developing means, and transfer means described above.

[0085] FIG. 2 shows an example of a schematic configuration of an electrophotographic apparatus having a process cartridge equipped with an electrophotographic photosensitive member. Reference numeral 1 denotes a cylindrical electrophotographic photoreceptor, which is driven to rotate around an axis 2 in the direction of the arrow at a predetermined peripheral speed. The surface of the electrophotographic photoreceptor 1 is charged to a predetermined positive or negative potential by a charging means 3. In the figure, a roller charging method using a roller-type charging member is shown, but a charging method such as a corona charging method, a proximity charging method, or an injection charging method may be adopted. Exposure light 4 is irradiated from an exposure means (not shown) onto the charged surface of the electrophotographic photoreceptor 1, and an electrostatic latent image corresponding to the target image information is formed. The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 1 is developed with toner contained in a developing means 5, and a toner image is formed on the surface of the electrophotographic photoreceptor 1. The toner image formed on the surface of the electrophotographic photoreceptor 1 is transferred to a transfer material 7 by a transfer means 6. The transfer material 7 to which the toner image has been transferred is transported to a fixing means 8, where the toner image is fixed, and the transfer material is printed out outside the electrophotographic device. The electrophotographic device may have a cleaning means 9 for removing deposits such as toner remaining on the surface of the electrophotographic photoreceptor 1 after transfer. Also, a so-called cleanerless system may be used in which the above-mentioned deposits are removed by the developing means 5 or the like, without providing a separate cleaning means 9. The electrophotographic apparatus may have a charge eliminating mechanism that eliminates charge on the surface of the electrophotographic photoreceptor 1 by pre-exposure light 10 from a pre-exposure means (not shown). Also, in order to mount and remove the process cartridge 11 according to the present invention to the main body of the electrophotographic apparatus, guide means 12 such as a rail may be provided.

[0086] The electrophotographic photoreceptor according to the present invention can be used in laser beam printers, LED printers, copiers, facsimiles, and combination machines thereof. EXAMPLES

[0087] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited to the following examples without departing from the gist of the present invention. In the following examples, "parts" are based on mass unless otherwise specified. In the examples, the polytetrafluoroethylene particles were prepared based on JP 2009-1745 A and JP 2010-180364 A, and the number average particle size of the primary particles (hereinafter also referred to as primary particle size), the abundance ratio, and the degree of crystallinity were calculated by the following measurement methods.

[0088] (Measurement of primary particle size and abundance ratio of polytetrafluoroethylene particles) The primary particle size and abundance ratio of polytetrafluoroethylene particles were measured using a field emission scanning electron microscope (FE-SEM). The polytetrafluoroethylene particles were attached to a commercially available carbon conductive tape, and the polytetrafluoroethylene particles not attached to the conductive tape were removed with compressed air, followed by platinum deposition. The deposited polytetrafluoroethylene particles were observed using a Hitachi High-Technologies Corporation FE-SEM (S-4700). The longest diameter was calculated by performing ellipse fitting on 200 primary particles using ImageJ (open source software from the National Institutes of Health (NIH)) from the obtained images. The longest diameter obtained was taken as the primary particle diameter, and the abundance ratio of polytetrafluoroethylene particles to the primary particle diameter was calculated from the obtained results.

[0089] (Measurement of crystallinity of polytetrafluoroethylene particles) The crystallinity of the polytetrafluoroethylene particles was measured by wide-angle X-ray diffraction under the following conditions. X-ray diffraction equipment: Bruker AXS D8 ADVANCE X-ray source: Cu-Kα ray (wavelength 0.15418nm) Output: 40kV, 40mA Slit system: Slit DS, SS=1°, RS=0.2mm Measurement range: 2θ=5°~60° Step interval: 0.02° Scan speed: 1° / min The wide-angle X-ray diffraction profile obtained under the above measurement conditions was separated into a crystal peak and an amorphous scattering peak, and the degree of crystallinity was calculated from their areas according to the following formula (a-1). Crystallinity (%)=Ic / (Ic+Ia)×100 Formula (a-1) Ic: Total area of ​​crystal peaks detected in the range of 5≦2θ≦60 Ia: Total area of ​​amorphous scattering detected in the range of 5≦2θ≦60

[0090] Example 1 An aluminum cylinder having a diameter of 30 mm, a length of 370.0 mm, and a wall thickness of 1 mm was used as a support (conductive support).

[0091] <Undercoat layer> Zinc oxide particles (specific surface area: 19 m) as metal oxide 2 / g, powder resistance: 4.7×10 6 100 parts of the solubility in water (Ω·cm) was mixed with 500 parts of toluene and stirred. 0.8 parts of a silane coupling agent, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane (product name: KBM603, Shin-Etsu Chemical Co., Ltd.), was added and stirred for 6 hours. After that, the toluene was distilled off under reduced pressure, and the mixture was dried by heating at 130°C for 6 hours to obtain surface-treated zinc oxide particles. Next, the following materials were prepared: - 15 parts of butyral resin (product name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) as polyol resin Blocked isocyanate (product name: Sumidur 3175, manufactured by Sumitomo Bayer Urethane Co., Ltd.) 15 parts These were dissolved in a mixed solution of 73.5 parts of methyl ethyl ketone and 73.5 parts of 1-butanol. 80.8 parts of the surface-treated zinc oxide particles and 0.81 parts of alizarin were added to this solution, and the mixture was dispersed in a sand mill using glass beads with a diameter of 0.8 mm under an atmosphere of 23±3° C. for 3 hours. Next, the following materials were prepared. Silicone oil (product name: SH28PA, manufactured by Toray Dow Corning Silicone Co., Ltd.) 0.01 part 0.007 parts by weight of dioctyltin dilaurate as a catalyst Silicone resin particles (Tospearl 145, manufactured by GE Toshiba Silicones) 5.4 parts by weight These were added to the above-mentioned dispersed solution and stirred to obtain a coating solution for the undercoat layer, which was then dip-coated onto the above-mentioned support, and the resulting coating was dried at 160° C. for 30 minutes to form an undercoat layer with a thickness of 18 μm.

[0092] <Charge generation layer> Hydroxygallium phthalocyanine having diffraction peaks at Bragg angles 2θ±0.2° at least 7.3°, 16.0°, 24.9°, and 28.0° in CuKα characteristic X-ray diffraction was prepared. 15 parts of this hydroxygallium phthalocyanine was mixed with 10 parts of vinyl chloride-vinyl acetate copolymer resin (VMCH, manufactured by Nippon Union Carbide Co., Ltd.) and 300 parts of n-butyl acetate. The mixture was dispersed for 4 hours in a sand mill using glass beads with a diameter of 1 mm under an atmosphere of 23±3°C. The coating liquid was dip-coated on the above undercoat layer and dried by heating at 100°C for 10 minutes to form a charge generating layer with a thickness of 0.20 μm.

[0093] <Charge transport layer> The following materials were prepared: Two parts of a compound represented by the following structural formula (A): Polycarbonate resin (product name: Iupilon Z400, manufactured by Mitsubishi Engineering Plastics Corporation, bisphenol Z type polycarbonate) 2.5 parts 0.05 parts of 2,6-di-t-butyl-4-methylphenol as an antioxidant These were dissolved in 35 parts of chlorobenzene to prepare a coating solution for the charge transport layer. The coating solution for the charge transport layer was dip-coated onto the charge generating layer to form a coating film, and the resulting coating film was dried at 120° C. for 40 minutes to form a charge transport layer with a thickness of 20 μm. [ka]

[0094] <Surface layer> The following materials were prepared: 52 parts of a charge-transporting compound represented by formula (2-2) 36 parts of a charge transport compound represented by formula (1-1) 12 parts of a charge transport compound represented by formula (1-9) Benzoguanamine resin (Nicalac BL-60, Sanwa Chemical Co., Ltd.) 1.5 parts 2.23 parts of a polymer having a structural unit represented by formula (3-9) and a structural unit represented by formula (4-2) (copolymerization ratio: formula (3-9) / formula (4-2)=1 / 1 (molar ratio), weight average molecular weight: 100,000) 500 parts cyclopentanone These were mixed and dissolved. Then, 44.5 parts of polytetrafluoroethylene particles (the proportion of particles with a primary particle diameter of 140 nm or more and the degree of crystallinity are shown in Table 2) were added and mixed by stirring. Then, the mixture was passed through a high-pressure disperser (product name: Microfluidizer M-110EH, manufactured by Microfluidics, Inc., USA) to obtain a dispersion liquid. Next, 0.2 parts of dodecylbenzenesulfonic acid catalyst (NACURE5225, manufactured by King Industries) was mixed and dissolved to obtain a prepared liquid. The dispersion was added to this mixture, stirred and mixed, and then filtered through a polytetrafluoroethylene filter (product name: PF-040, manufactured by Advantec Toyo Co., Ltd.) to prepare a coating solution for the surface layer. This coating solution was dip-coated onto the charge transport layer, and the resulting coating film was heat-treated at 155°C for 60 minutes to form a surface layer with a thickness of 5.0 μm. In this manner, an electrophotographic photoreceptor having an undercoat layer, a charge generating layer, a charge transport layer, and a surface layer in this order on a support (conductive support) was produced.

[0095] Example 2 In Example 1, the polymer having the structural unit represented by formula (3-9) and the structural unit represented by formula (4-2) used in the preparation of the surface layer coating liquid was changed to a polymer having the structural unit represented by formula (3-5) and the structural unit represented by formula (4-6). The polymer having the structural unit represented by formula (3-5) and the structural unit represented by formula (4-6) had a copolymerization ratio of formula (3-5) / formula (4-6)=1 / 1 (molar ratio) and a weight average molecular weight of 110,000. Except for this, an electrophotographic photoreceptor was produced in the same manner as in Example 1.

[0096] Example 3 In Example 1, 1.5 parts of the benzoguanamine resin (Nikarak BL-60, manufactured by Sanwa Chemical Co., Ltd.) used in the preparation of the surface layer coating liquid was changed to 1.5 parts of a melamine compound (Nikarak MW-30HM, manufactured by Sanwa Chemical Co., Ltd.). Otherwise, an electrophotographic photoreceptor was produced in the same manner as in Example 1.

[0097] (Examples 4 to 19, Comparative Examples 1 to 7) In Example 1, the types and amounts of the charge transport compound represented by formula (1) and the charge transport compound represented by formula (2) in the surface layer coating liquid were as shown in Table 1. The abundance ratio of polytetrafluoroethylene particles having a primary particle diameter of 140 nm or more, the degree of crystallinity, and the content in the surface layer were as shown in Table 2. Except for this, an electrophotographic photoreceptor was produced in the same manner as in Example 1.

[0098] [Table 1]

[0099] [Table 2]

[0100] [evaluation] The electrophotographic photoreceptors produced in Examples 1 to 19 and Comparative Examples 1 to 7 were evaluated for ghost images and electrical characteristics as follows.

[0101] (Ghost image evaluation) A copying machine (product name: imagePRESS C910, manufactured by Canon Inc.) was used as the electrophotographic apparatus for evaluation. The electrophotographic photoreceptor was left together with the copier in a high-temperature and high-humidity environment of 32°C and 82%RH for 3 days. After that, the laser light quantity and applied voltage were adjusted so that the initial light potential was -300 [V] and the dark potential was -800 [V]. Then, 10,000, 30,000, and 50,000 sheets were passed through in the same environment. Under the above laser light quantity conditions, ghost images were evaluated immediately after passing through the sheets, and immediately after passing through the sheets of 10,000, 30,000, and 50,000. The electrophotographic photoreceptor was used in an intermittent mode in which 50 sheets were continuously fed and then the feeding was stopped for 10 seconds, and this was repeated under the condition that 0.5 mm wide lines were printed vertically at 10 mm intervals. The ghost image evaluation was performed as follows. After the paper was passed through the paper feed tray, an image for evaluating the ghost image and an all-white image were printed. As the image for evaluating the ghost image, as shown in FIG. 3(a), a square solid image 32 was printed on a white background (white image 31) at the beginning of the image, and then a one-dot knight pattern image 33 was produced. The one-dot knight pattern image in FIG. 3(a) is a pattern image as shown in FIG. 3(b). In FIG. 3(a), the ghost evaluation section 34 is a section for evaluating the presence or absence of a ghost caused by the solid image. If a ghost appears, it appears in the ghost evaluation section 34 in FIG. 3(a). In the evaluation of the ghost image, the density difference between the image density of the one-dot knight pattern image 33 and the image density of the ghost evaluation part 34 was measured with a spectrodensitometer (product name: X-Rite504 / 508, manufactured by X-Rite). The smaller the value of this density difference, the smaller the degree of the ghost phenomenon and the better it is. The ghost image evaluation was performed according to the following criteria according to the density difference. Rank 5: Image density difference is greater than 0.000 and less than or equal to 0.015 Rank 4: Image density difference is 0.016 to 0.025 Rank 3: Image density difference is 0.026 to 0.035 Rank 2: Image density difference is 0.036 to 0.050 Rank 1: Image density difference is 0.051 or more The evaluation results obtained are shown in Table 3.

[0102] (Electrical property evaluation) The above-mentioned copying machine was used as the electrophotographic apparatus for evaluation. An electrophotographic photoreceptor was attached to the drum cartridge of this copying machine, and the following evaluation was performed. In a high-temperature and high-humidity environment with a temperature of 32° C. and a humidity of 82% RH, images with an image printing ratio of 5% were continuously formed on 20,000, 30,000, and 50,000 sheets of A4-sized plain paper. After outputting 20,000 images, the applied voltage condition (applied voltage setting C) and the exposure light amount condition (exposure light amount C) of the exposure device were set so that the dark area potential (Vd) of the obtained electrophotographic photoconductor was −850 [V] and the light area potential (Vl) was −300 [V]. The surface potential of the electrophotographic photoconductor was measured by removing the developing cartridge from the copier, fixing a potential probe (product name: model 60006-8, manufactured by Trek Corporation) thereto, and using a surface potential meter (model 344, manufactured by Trek Corporation). The developing cartridge was replaced with a potential measuring device consisting of the above potential probe and surface potential meter, the above applied voltage setting C was applied, and the light area potential (Vla) of the surface of the electrophotographic photosensitive member when exposed to the above exposure light amount C was measured. Thereafter, while maintaining the applied voltage condition (applied voltage setting C) and the exposure light amount condition (exposure light amount C) of the exposure device, 1000 sheets were continuously output with a solid black image setting. Thereafter, the bright area potential fluctuation difference |ΔVl| during the continuous output of 1000 sheets was calculated from the difference between the maximum value (ΔVlmax) and the minimum value (ΔVlmin) of the bright area potential on the surface during the continuous output of 1000 sheets. After outputting 30,000 and 50,000 images, the same operation as that after outputting 20,000 images was carried out. The smaller the bright area potential fluctuation difference, the smaller the degree of potential fluctuation and the better the result. The electrical characteristics were evaluated according to the bright area potential fluctuation difference |ΔVl| using the following criteria. Rank 4: |ΔVl| is within 10 Rank 3: |ΔVl| is greater than 10 and less than 15 Rank 2: |ΔVl| is greater than 15 and less than 20 Rank 1: |ΔVl| is greater than 20

[0103] The evaluation results obtained are shown in Table 3. [Table 3] [Explanation of symbols]

[0104] 111 Support 112 Undercoat layer 113 Charge generation layer 114 Charge transport layer 115 Surface layer 1. Electrophotographic photoreceptor 2-axis 3. Charging means 4 Exposure light 5. Developing method 6 Transfer Method 7 Transfer material 8 Fixing Method 9 Cleaning Method 10 Pre-exposure light 11 Process cartridge 12 Guidance means

Claims

1. An electrophotographic photoreceptor having a support, a photosensitive layer, and a surface layer in this order, The surface layer is A charge transporting compound represented by the following formula (1): A charge transporting compound represented by the following formula (2): Polytetrafluoroethylene particles; The composition contains a cured product of the composition, the content ratio of the charge transporting compound represented by the following formula (1) to the charge transporting compound represented by the following formula (2) in the composition (charge transporting compound represented by formula (1):charge transporting compound represented by formula (2)) is within a range of 40:60 to 60:40, The number average particle diameter of the primary particles of the polytetrafluoroethylene particles is 110 nm or more and 130 nm or less, The content of the polytetrafluoroethylene particles in the surface layer is 16% by mass or more based on the total mass of the surface layer.

1. An electrophotographic photoreceptor comprising: 【Chemistry 1】 (In formula (1), Ar １１ ~Ar １３ each independently represents a phenyl group which may have a substituent. １１ ~Ar １３ The substituent that the phenyl group represented by the formula (I) may have is a group selected from the group consisting of a methyl group, an ethyl group, a methoxy group, a hydroxyalkyl group, and an alkoxyalkyl group, and when a plurality of substituents are present, the plurality of substituents may be the same or different from each other. １１ ~Ar １３ Two of the phenyl groups represented by the formula (1) have a hydroxyalkyl group or an alkoxyalkyl group as a substituent, and the total number of the hydroxyalkyl groups and the alkoxyalkyl groups contained in the charge transporting compound represented by the formula (1) is 2. 【Chemistry 2】 (In formula (2), Ar ２１ ~Ar ２４ each independently represents a phenyl group having a substituent; Ar ２５ ~Ar ２６ Each of Ar independently represents a phenylene group which may have a substituent. ２１ ~Ar ２４ Each of the phenyl groups represented by the formula (I) has one of a hydroxyalkyl group or an alkoxyalkyl group as a substituent, and Ar ２１ ~Ar ２４ The phenyl group represented by the formula (I) may further have one or more substituents selected from the group consisting of a methyl group, an ethyl group, and a methoxy group. ２５ ~Ar ２６ The substituent that the phenylene group represented by the formula (I) may have is a group selected from the group consisting of a methyl group and an ethyl group.

2. Ar in the formula (2) ２１ ~Ar ２４ 2. The electrophotographic photoreceptor according to claim 1, wherein each of the groups is a phenyl group having one hydroxymethyl group as a substituent.

3. 3. The electrophotographic photoreceptor according to claim 1, wherein a content ratio of the polytetrafluoroethylene particles in the surface layer is from 20% by mass to 40% by mass with respect to a total mass of the surface layer.

4. 4. The electrophotographic photoreceptor according to claim 1, wherein the polytetrafluoroethylene particles having a primary particle diameter of 140 nm or more in the surface layer have an abundance ratio of 10% by number or less relative to the total number of the polytetrafluoroethylene particles.

5. 5. The electrophotographic photoreceptor according to claim 1, wherein the polytetrafluoroethylene particles have a degree of crystallinity of 70% or more and 75% or less.

6. 6. A process cartridge which integrally supports the electrophotographic photosensitive member according to any one of claims 1 to 5 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.

7. 6. An electrophotographic apparatus comprising the electrophotographic photoreceptor according to claim 1, a charging means, an exposing means, a developing means and a transferring means.

Images