Electrophotographic photoreceptor, process cartridge having the electrophotographic photoreceptor, and electrophotographic apparatus

Abstract

To provide an electrophotographic photoreceptor comprising an undercoat layer that suppresses occurrence of cracks associated with long-term use, and to provide a process cartridge employing the electrophotographic photoreceptor and an electrophotographic device having the process cartridge.SOLUTION: An electrophotographic photoreceptor provided herein has an undercoat layer containing a perinone compound having a specific structure and carbon black.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. [Background technology]

[0002] Electrophotographic photoreceptors containing organic photoconductive materials (charge-generating materials) are widely used in electrophotographic devices. In recent years, as electrophotographic devices have become faster and produced higher image quality, high potential stability is required in electrophotographic photoreceptors.

[0003] Specifically, it is necessary to suppress potential fluctuations during repeated use and to improve the potential uniformity within the photoreceptor's peripheral surface, which is related to the uniformity of density within the plane of the output image.

[0004] One technique for suppressing potential fluctuations during repeated use is to include an electron-transporting compound in the undercoat of the electrophotographic photoreceptor. As a technique for improving potential uniformity, a technique is known to absorb or scatter the image exposure that reaches the undercoat in order to improve potential unevenness caused by interference of image exposure within the photoreceptor. One technique for absorbing the image exposure that reaches the undercoat is to include carbon black in the undercoat. Patent Document 1 describes a technique for including carbon black and a hydrazone compound as an electron-transporting compound. [Prior art documents] [Patent Documents]

[0005] [Patent Document 1] Japanese Patent Application Publication No. 1-113758 [Overview of the project] [Problems that the invention aims to solve]

[0006] However, while the electrophotographic photoreceptors of the prior art described above exhibited excellent suppression of potential fluctuations, there was room for improvement in terms of long-term repeated use. Specifically, there was a problem in that cracks tended to occur on the surface of the undercoat layer during prolonged use, which led to image defects when the goal was to achieve high image quality.

[0007] The object of the present invention is to provide an electrophotographic photoreceptor having an undercoat that suppresses the occurrence of cracks during prolonged use, and a method for manufacturing the same.

[0008] Another object of the present invention is to provide a process cartridge equipped with the electrophotographic photoreceptor, and an electrophotographic apparatus equipped with the process cartridge. [Means for solving the problem]

[0009] The above objectives are achieved by the present invention as follows: That is, the present invention is An electrophotographic photoreceptor having a support, an undercoat, and a photosensitive layer in this order, The lower layer , Linone compounds, and Contains carbon black. death, The perinone compound is the compound represented by the following formula (5) and the compound represented by the following formula (6), The content of the perinone compound in the undercoat is 30% by mass or more and 60% by mass or less relative to the total mass of the undercoat. The carbon black content in the undercoat is 0.5% by mass or more and 20% by mass or less relative to the total mass of the undercoat. The carbon black content in the undercoat is 1% by mass or more and 70% by mass or less relative to the perinone compound content in the undercoat. This is an electrophotographic photoreceptor characterized by the following features. [ka] [ka] (R in equation (5)) 51 ~R 56 Also, R in equation (6) 61 ~R 66 These independently represent a methyl group, an ethyl group, or a propyl group.

[0010] Furthermore, the present invention provides a process cartridge 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 detachably attached to the main body of an electrophotographic apparatus.

[0011] Furthermore, the present invention relates to an electrophotographic apparatus having the electrophotographic photoreceptor, charging means, exposure means, developing means, and transfer means. [Effects of the Invention]

[0012] According to the present invention, it is possible to provide an electrophotographic photoreceptor having an undercoat layer that suppresses the occurrence of cracks in the undercoat layer during prolonged use, and a method for manufacturing the same. Furthermore, according to the present invention, it is possible to provide a process cartridge having the electrophotographic photoreceptor, and an electrophotographic apparatus. [Brief explanation of the drawing]

[0013] [Figure 1] This is a schematic diagram showing an example of the configuration of the electrophotographic photoreceptor of the present invention. [Figure 2] This figure shows an example of a schematic configuration of a process cartridge equipped with the electrophotographic photoreceptor of the present invention, and an electrophotographic apparatus equipped with the process cartridge. [Modes for carrying out the invention]

[0014] The electrophotographic photoreceptor of the present invention comprises a support, an undercoat layer, and a photosensitive layer in this order. The undercoat layer comprises at least one perinone compound selected from the group consisting of the compound represented by formula (1) and the compound represented by formula (2) below, and carbon black. Furthermore, the method for manufacturing an electrophotographic photoreceptor having a support, an undercoat layer, and a photosensitive layer in this order according to the present invention includes a step of preparing a coating liquid for the undercoat layer, and a step of forming a coating film of the coating liquid for the undercoat layer and drying and / or curing the coating film to form the undercoat layer, wherein the coating liquid for the undercoat layer contains at least one perinone compound selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2), and carbon black.

[0015] As a result of intensive studies by the present inventors, it has been found that by including at least one perinone compound selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2), and carbon black in the undercoat layer, the occurrence of cracks in the undercoat layer during long-term use is suppressed.

Chemical formula

Chemical formula

[0016] Regarding the reason, the present inventors have speculated as follows. By including carbon black and a perinone compound with a specific structure in the undercoat layer, electrical degradation of the carbon black during prolonged use is suppressed because electrons are delocalized and stabilized between the perinone compound and the carbon black. In other words, it is hypothesized that cracks in the undercoat layer occurred due to the electrical degradation of the carbon black, but by combining it with the perinone compound, electrical degradation is suppressed, and as a result, the occurrence of cracks in the undercoat layer is suppressed.

[0017] Here, the content of the perinone compound in the undercoat is preferably 30% to 60% by mass relative to the total mass of the undercoat. Furthermore, the content of the carbon black in the undercoat is more preferably 0.5% to 20% by mass relative to the total mass of the undercoat. Moreover, the carbon black content is more preferably 1% to 70% by mass relative to the mass of the perinone compound.

[0018] Furthermore, the average primary particle size of the carbon black is preferably between 10 nm and 200 nm.

[0019] Furthermore, it is more preferable that the perinone compound has one perinone compound selected from the group consisting of compounds represented by the following formula (3) or formula (4). Furthermore, it is more preferable that the perinone compound has one perinone compound selected from the group consisting of compounds represented by the following formula (5) or formula (6). [ka] [ka] [ka] [ka]

[0020] R in equation (3) 31 and R32 , and R in equation (4) 41 and R 42 Each of these independently represents a branched alkyl group with a total number of carbon atoms between 3 and 10.

[0021] R in equation (5) 51 , R 52 , R 53 , R 54 , R 55 and R 56 , and R in equation (6) 61 , R 62 , R 63 , R 64 , R 65 and R 66 These independently represent a methyl group, an ethyl group, or a propyl group.

[0022] The embodiments for carrying out the present invention will be described in detail below. [Electrophotographic photoconductor] The electrophotographic photoreceptor according to the present invention has a support and a photosensitive layer in this order. The electrophotographic photoreceptor in this embodiment has a support, an undercoat, and a photosensitive layer in that order. A more preferred configuration is one in which a support, an undercoat layer, a charge generation layer, and a charge transport layer are laminated in this order, in which case the charge generation layer and the charge transport layer are photosensitive layers.

[0023] Figure 1 shows a stacked photosensitive layer having a photosensitive layer in which a charge generation layer and a charge transport layer are stacked in that order. In Figure 1, a conductive layer 102, an undercoat layer 103, a charge generation layer 104, a charge transport layer 105, and a protective layer 106 are laminated on a support 101. The charge generation layer 104, the charge transport layer 105, and the protective layer 106 together are called the photosensitive layer 107. In the present invention, the conductive layer 102 and the protective layer 106 may be omitted. The following describes each layer in the following order: support layer, conductive layer, undercoat layer, photosensitive layer, and protective layer.

[0024] <Support> The support is a conductive support. The support can take various shapes, including cylindrical, belt-shaped, and sheet-shaped. A cylindrical shape 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 their alloys. Of these, aluminum is preferred. Furthermore, when using resin or glass as the base material, it is preferable that the material is treated by mixing or coating it with a conductive material to impart conductivity.

[0025] <Conductive layer> A conductive layer is a layer that may be added if necessary. The conductive layer is a layer that may be placed on top of the conductive support and between the conductive support and the photosensitive layer, more specifically, in the order of conductive support, conductive layer, undercoat layer, and photosensitive layer. By providing a conductive layer, scratches and irregularities on the surface of the conductive support can be concealed, and light reflection on the support surface can be controlled. The conductive layer contains conductive particles and resin.

[0026] Examples of materials used for conductive particles include metal oxides and metals. 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. Among these, metals include aluminum, nickel, iron, nichrome, copper, zinc, and silver. Among the materials of the conductive particles, metal oxides are preferred, and titanium oxide, tin oxide, and zinc oxide are more preferred. Furthermore, with respect to metal oxides, the surface of the metal oxide may be treated with a silane coupling agent or similar, or it may be doped with the element itself, such as phosphorus or aluminum, or its oxides. Furthermore, the conductive particles may have a laminated structure comprising a core material and a coating layer covering it. Examples of core materials include titanium oxide, barium sulfate, and zinc oxide. Examples of coating layers include metal oxides such as tin oxide. The coating layer and the surface treated with the silane coupling agent are significantly thicker in the former than in the latter. Furthermore, when using metal oxides as conductive particles, their volume-average particle size is preferably 1 nm to 500 nm, and more preferably 3 nm to 400 nm.

[0027] 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 contain silicone oil, resin particles, a concealing agent such as titanium dioxide, and the like.

[0028] The conductive layer can be obtained by applying a coating film of a conductive layer coating solution containing the above-mentioned materials and solvents onto a support, and then drying the coating film.

[0029] Solvents used in coating solutions include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0030] Methods for dispersing conductive particles in a coating solution for a conductive layer include using a paint shaker, sand mill, ball mill, or liquid impaction type high-speed disperser.

[0031] The average thickness of the conductive layer is preferably 0.1 μm or more and 50 μm or less, and particularly preferably 3 μm or more and 40 μm or less.

[0032] <Underlayer> In the electrophotographic photoreceptor according to this embodiment, the undercoat layer is provided on a conductive support or conductive layer. Providing the undercoat layer enhances the interlayer adhesion function and improves the electrical properties. The undercoat layer according to the present invention contains a perinone compound and carbon black. The perinone compound and carbon black contained in the undercoat layer according to the present invention will be described below.

[0033] (Perinone compound) The underlayer according to the present invention contains a perinone compound as a charge transport compound (ETM). The perinone compound in the present invention is at least one compound selected from the group consisting of perinone compound (1) and perinone compound (2). Perinone compound (1) is a compound represented by the following formula (1). Perinone compound (2) is a compound represented by the following formula (2). [ka] [ka] R in equation (1) 11 ~R 18 , and R in equation (2) 21 ~R 28 Each of these independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted alkoxycarbonyl group, R 11 ~R 14 , R 15 ~R 18 , R 21 ~R 24 and R 25 ~R 28 Within each group, adjacent groups may be linked together to form a ring. Alkyl alkyl groups are linear or branched alkyl groups with 1 to 10 atoms in the main chain.

[0034] In particular, from the viewpoint of improving hole blocking properties and suppressing the increase in dark decay, it is preferable that the branched alkyl group has 3 to 10 carbon atoms. Specifically, in formula (1), R 11 , R 12 , R 13 , R 14 , R 15 , R 16 , R 17 and R 18 Preferably, each of the elements is a branched alkyl chain having 3 to 10 carbon atoms, as shown in formulas (3) and (4). Furthermore, it is even more preferable that the alkyl chain is divided into three branches, each having 1 to 3 carbon atoms, as shown in formulas (5) and (6). In equation (2), R 21 , R 22 , R 23 , R 24 , R 25 , R 26 , R 27 and R 28 Preferably, each of the elements is a branched alkyl chain having 3 to 10 carbon atoms, as shown in formulas (3) and (4). Furthermore, it is even more preferable that the alkyl chain is divided into three branches, each having 1 to 3 carbon atoms, as shown in formulas (5) and (6). [ka] [ka] [ka] [ka] R in equation (3) 31 and R 32 , and R in equation (4) 41 and R 42 Each of these independently represents a branched alkyl group with a total number of carbon atoms between 3 and 10. R in equation (5) 51 , R 52 , R 53 , R54 , R 55 and R 56 , and R in equation (6) 61 , R 62 , R 63 , R 64 , R 65 and R 66 These independently represent a methyl group, an ethyl group, or a propyl group.

[0035] Examples of substituents on alkyl groups include halogen atoms, aryl groups, and alkoxycarbonyl groups. Substituents for the aryl group include halogen atoms, alkyl groups, and alkoxycarbonyl groups, with aryl groups having 6 to 10 carbon atoms being preferred, and phenyl groups being particularly preferred. Substituents for the aryloxy group include halogen atoms, alkyl groups, and alkoxycarbonyl groups, with aryloxy groups having 6 to 10 carbon atoms being preferred, and phenyloxy groups being particularly preferred. Substituents for the alkoxycarbonyl group include halogen atoms, alkyl groups, and aryl groups, with alkoxycarbonyl groups having 1 to 10 carbon atoms being preferred, and particularly preferred are methoxycarbonyl groups, ethoxycarbonyl groups, and propoxycarbonyl groups.

[0036] In equations (1) and (2), R 11 ~R 14 , R 15 ~R 18 , R 21 ~R 24 and R 25 ~R 28 Within each group, adjacent substituents may be linked together to form a ring. It is particularly preferable that an aromatic ring is formed, and as the aromatic ring, a naphthalene ring and an anthracene ring are particularly preferred.

[0037] Specific examples of perinone compound (1) and perinone compound (2) are shown below, but this embodiment is not limited to these.

[0038] [ka] [ka]

[0039] In the undercoat layer, the carbon black content is preferably 1% by mass or more and 70% by mass relative to the mass of the perinone compound. If the carbon black content is less than 1% by mass relative to the mass of the perinone compound, the proportion of carbon black, which has excellent electron-carrying properties, decreases, and short-term potential fluctuations worsen. On the other hand, if the carbon black content exceeds 70% by mass relative to the mass of the perinone compound, the proportion of perinone compound that interacts in close proximity with the carbon black decreases, making it difficult for electrons to delocalize between the perinone compound and the carbon black, leading to instability, and it is expected that crack formation during long-term use will not be suppressed.

[0040] (Carbon Black) The undercoat layer according to the present invention contains carbon black (CB). The DBP oil absorption capacity of carbon black is, for example, 30 ml / 100g to 400 ml / 100g, and preferably 50 ml / 100g to 200 ml / 100g. DBP absorption is the amount of dibutyl phthalate (DBP) absorbed by 100g of carbon black, and is a value defined in ASTM (American Standard Test Procedure) D2414-6TT. Furthermore, when two or more types of carbon black are used in combination, the DBP oil absorption amount of the carbon black shall be the weighted average value of the respective carbon black content of each of the two or more types.

[0041] The pH of the carbon black is not particularly limited, but for example, it is between 2 and 10, and preferably between 5 and 9. The above pH is the pH of an aqueous solution obtained by adding 50g of carbon black to 1000ml of water at 20°C, and is a value measured according to the pH measurement method specified in JIS Z8802 (2011). When two or more types of carbon black are used in combination, the pH of the carbon black shall be the weighted average value based on the content of each of the two or more types of carbon black.

[0042] From the viewpoint of dispersibility, the average primary particle size of the carbon black is, for example, 10 nm to 200 nm, and preferably 20 nm to 50 nm. When the average primary particle size of carbon black is less than 10 nm, it is expected that the relatively small particle size will cause interactions with the perinone compound, and the electron transfer will not be efficient due to the close proximity of the carbon black to the compound. As a result, short-term potential fluctuations will worsen. Furthermore, when the average primary particle size of carbon black exceeds 200 nm, it is expected that electron delocalization between the perinone compound and carbon black will not be possible, which will become the starting point for crack formation during long-term use.

[0043] The average primary particle size of carbon black is measured by the following method. The intermediate layer of the photoreceptor is cut using a microtome, and a measurement sample with a thickness of 200 nm is taken. This measurement sample is then observed using a TEM (transmission electron microscope). The diameters of 50 primary carbon black particles are then measured, and the average value is defined as the average primary particle size.

[0044] In this invention, carbon black may be used alone or in combination of two or more types.

[0045] Although carbon black exhibits different conductivity due to differences in physical properties such as DBP oil absorption and specific surface area obtained by the BET method utilizing nitrogen adsorption, two or more types of carbon black with different conductivity may be used in combination. When adding two or more types of carbon black with different physical properties in this way, for example, a carbon black exhibiting high conductivity may be added preferentially, followed by the addition of a carbon black with lower conductivity to adjust the volume resistivity.

[0046] The carbon black content is preferably between 0.5% and 20% by mass relative to the total mass of the undercoat. If the carbon black content falls below 0.5% by mass relative to the total mass of the undercoat, the conductive paths decrease, resulting in insufficient electron transport and worsening of short-term potential fluctuations. Furthermore, if the carbon black content exceeds 20% by mass relative to the total mass of the undercoat, the likelihood of carbon black particles being adjacent to each other increases, which is predicted to become the starting point for crack formation during prolonged use.

[0047] The undercoat layer contains a resin. Alternatively, the resin may be obtained as a cured film by polymerizing a composition containing monomers having polymerizable functional groups in the coating solution (curing by monomer polymerization).

[0048] 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.

[0049] 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.

[0050] Furthermore, the undercoat layer may contain electron transport materials, metal oxides, metals, etc., for the purpose of improving electrical properties. 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 oxides include indium tin oxide, tin oxide, indium oxide, titanium oxide, zinc oxide, aluminum oxide, strontium titanate, and silicon dioxide. Examples of metals include gold, silver, and aluminum.

[0051] The metal oxides contained in the undercoat may be surface-treated using a surface treatment agent such as a silane coupling agent before use. Common methods for surface treatment of metal oxides include dry methods 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 a metal oxide while stirring it in a high-speed mixer such as a Henschel mixer, and then drying it after uniform dispersion. In the wet method, the metal oxide and surface treatment agent are stirred in a solvent or dispersed using glass beads or the like in a sand mill. After dispersion, the solvent is removed by filtration or reduced-pressure distillation. After solvent removal, it is preferable to further bake the product at 100°C or higher.

[0052] The undercoat layer may further contain additives, such as known materials including metal powders like aluminum, conductive materials like carbon black, metal chelate compounds, and organometallic compounds.

[0053] 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.

[0054] 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 the present invention, it is preferable to use alcohol-based or ketone-based solvents.

[0055] 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.

[0056] The average thickness of the undercoat layer is preferably 0.05 μm or more and 50 μm or less, and more preferably 0.3 μm or more and 25 μm or less.

[0057] <Photosensitive layer> The photosensitive layer of the electrophotographic photoreceptor of the present invention may be either (1) a multilayer photosensitive layer or (2) a single-layer photosensitive layer. (1) A multilayer photosensitive layer is a photosensitive layer having a configuration in which a charge generating layer containing a charge generating material, a charge transport layer containing a charge transport material, and a protective layer are arranged in order in the thickness direction. (2) A single-layer photosensitive layer is a photosensitive layer containing a charge generating material, a charge transport material, and a resin in a single layer.

[0058] (1) Stacked photosensitive layer The stacked photosensitive layer comprises a charge generation layer and a charge transport layer. A protective layer may be provided on the charge transport layer as needed.

[0059] (1-1) Charge generation layer The charge generation layer contains a charge generation material and a resin.

[0060] Examples of charge-generating materials include azo compounds, perylene compounds, polycyclic quinone compounds, indigo compounds, and phthalocyanine compounds. Among these, azo compounds and phthalocyanine compounds are preferred. Among phthalocyanine compounds, titanyl phthalocyanine compounds, chlorogallium phthalocyanine compounds, and hydroxygallium phthalocyanine compounds are more 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.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] The average thickness of the charge generation layer is preferably 0.01 μm or more and 5 μm or less, and more preferably 0.15 μm or more and 0.4 μm or less.

[0065] (1-2) Charge transport layer The charge transport layer is obtained by dispersing a charge transport material and, if necessary, a binder resin in a solvent to prepare a coating solution for the charge transport layer, forming a coating film of the charge transport layer coating solution, and then drying it.

[0066] Examples of charge transport materials include triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, and triallylmethane compounds. Polymers having groups derived from these compounds in their main chain or side chains are also examples. Among these, triarylamine compounds, styryl compounds, or benzidine compounds are preferred as charge transport materials, with triarylamine compounds being particularly preferred. Furthermore, the charge transport materials can be used individually or in combination of one or more types.

[0067] Examples of binder resins used in the charge transport layer include polyvinyl butyral resin, polyvinyl acetal resin, polyarylate resin, polycarbonate resin, polyester resin, polyvinyl acetate resin, polysulfone resin, polystyrene resin, phenoxy resin, polyvinyl acetate resin, acrylic resin, phenoxy resin, polyacrylamide resin, polyamide resin, polyvinylpyridine resin, cellulose resin, urethane resin, epoxy resin, agarose resin, cellulose resin, casein resin, polyvinyl alcohol resin, polyvinylpyrrolidone resin, vinylidene chloride resin, acrylonitrile copolymer, and polyvinylbenzal resin (insulating resins). Organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, and polyvinylpyrene can also be used. Among these, polycarbonate resin and polyarylate resin are preferred. Furthermore, only one type of binder resin may be used, or two or more types may be used in combination as a mixture or copolymer. The copolymerization form may be any of the following: block copolymer, random copolymer, alternating copolymer, etc. Furthermore, the molecular weights of these materials are preferably in the range of weight-average molecular weight (Mw) = 10,000 to 300,000.

[0068] The content of the charge transport material in the charge transport layer is preferably 20 to 80% by mass, and more preferably 30 to 60% by mass, relative to the total mass of the charge transport layer. The thickness of the charge transport layer is preferably 5 μm or more and 40 μm or less.

[0069] (1-3) Protective layer A protective layer may be provided on the charge transport layer as needed. The protective layer is obtained by dissolving a resin in an organic solvent to prepare a protective coating solution, forming a coating film of the protective coating solution, and then drying it. Alternatively, the protective layer can also be formed by curing the coating film with heat, electron beams, ultraviolet light, etc.

[0070] Examples of resins used in the protective layer include polyvinyl butyral resin, polyester resin, polycarbonate resin (such as polycarbonate Z resin and modified polycarbonate resin), nylon resin, polyimide resin, polyarylate resin, polyurethane resin, styrene-butadiene copolymer, styrene-acrylic acid copolymer, and styrene-acrylonitrile copolymer.

[0071] Furthermore, in order to give the protective layer charge transport ability, the protective layer may be formed by curing a monomer having charge transport ability using various polymerization and crosslinking reactions. Specifically, it is preferable to form the protective layer by polymerizing or crosslinking a charge transport compound having a chain polymerizable functional group and then curing it.

[0072] Furthermore, the protective layer may contain conductive particles, UV absorbers, lubricating particles such as fluorine atom-containing resin fine particles, etc. As conductive particles, metal oxide particles such as tin oxide particles are preferred. The thickness of the protective layer is preferably 0.05 to 20 μm.

[0073] For each layer, coating methods such as dipping, spray coating, spinner coating, bead coating, blade coating, and beam coating can be used. Among these, dipping is preferred from the viewpoint of efficiency and productivity.

[0074] (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.

[0075] [Process cartridges, electrophotographic equipment] The process cartridge of the present invention is characterized in that it integrally supports the electrophotographic photoreceptor of the present invention as described above, and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, and is detachably attached to the electrophotographic apparatus body.

[0076] Furthermore, the electrophotographic apparatus of the present invention is characterized by having the electrophotographic photoreceptor, charging means, exposure means, developing means, and transfer means described above.

[0077] Figure 2 shows an example of a schematic configuration of an electrophotographic apparatus having a process cartridge 11 equipped with an electrophotographic photoreceptor 1. The cylindrical (drum-shaped) electrophotographic photoreceptor 1 is driven to rotate around the axis 2 in the direction of the arrow at a predetermined peripheral speed (process speed). During the rotation process, the surface of the electrophotographic photoreceptor 1 is charged to a predetermined positive or negative potential by the charging means 3.

[0078] Although Figure 2 shows a roller charging method using a roller-type charging member, other charging methods such as corona charging, proximity charging, and injection charging may also be used. Exposure light 4 is irradiated onto the surface of the charged electrophotographic photoreceptor 1 from an exposure means (not shown), and an electrostatic latent image corresponding to the desired image information is formed.

[0079] The exposure light 4 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 1 is developed (normal development or inverted development) with toner contained in the developing means 5, and a toner image is formed on the surface of the electrophotographic photoreceptor 1.

[0080] The toner image formed on the surface of the electrophotographic photoreceptor 1 is transferred to the transfer material 7 by the transfer means 6. At this time, a bias voltage with the opposite polarity to the charge held by the toner is applied to the transfer means 6 from a bias power supply (not shown). If the transfer material 7 is paper, the transfer material 7 is taken out from the paper feed unit (not shown) and fed between the electrophotographic photoreceptor 1 and the transfer means 6 in synchronization with the rotation of the electrophotographic photoreceptor 1.

[0081] The transfer material 7, onto which the toner image has been transferred from the electrophotographic photoreceptor 1, is separated from the surface of the electrophotographic photoreceptor 1 and transported to the fixing means 8, where it undergoes a toner image fixing process and is printed out as an image-forming product (print, copy) outside the electrophotographic apparatus. The electrophotographic apparatus may also have a cleaning means 9 for removing any toner or other deposits remaining on the surface of the electrophotographic photoreceptor 1 after the transfer.

[0082] 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.

[0083] In the present invention, a process cartridge 11 can be formed by housing multiple components selected from the above-mentioned electrophotographic photoreceptor 1, charging means 3, developing means 5, and cleaning means 9 in a container and supporting them integrally. This process cartridge can then be configured to be detachably attached to the electrophotographic apparatus body.

[0084] For example, the system can be configured as follows: At least one selected from the charging means 3, developing means 5, and cleaning means 9 is integrally supported with the electrophotographic photoreceptor 1 to form a cartridge. This can then be used to create a process cartridge 11 that is detachable from the electrophotographic apparatus using guide means 12 such as rails on the electrophotographic apparatus body.

[0085] The electrophotographic apparatus may have a static elimination mechanism that removes static electricity from the surface of the electrophotographic photoreceptor 1 using pre-exposure light 10 from a pre-exposure means (not shown). Furthermore, guide means 12, such as rails, may be provided for attaching and detaching the process cartridge 11 of the present invention to the electrophotographic apparatus body.

[0086] The electrophotographic apparatus of the present invention is characterized by comprising an electrophotographic photoreceptor 1, and at least one means selected from the group consisting of a charging means 3, an exposure means, a developing means 5, and a transfer means 6.

[0087] The electrophotographic photoreceptor of the present invention can be used in laser beam printers, LED printers, copiers, facsimile machines, and multifunction devices thereof. [Examples]

[0088] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited in any way by the following examples unless it exceeds the gist of the invention. In the following examples, "parts" refers to mass unless otherwise specified. Furthermore, in the following description, Examples 2-16, 19, 20, 23, 24, 26, and 29 are for reference only.

[0089] <Carbon Black (CB) Adjustment Example 1> Carbon black #30 (product name: General-purpose color (RCF) #30, pH 8, volatile content 0.6% by mass, DBP oil absorption (granular): 104 ml / 100 g, volume average particle size: 30 nm, manufactured by Mitsubishi Chemical Corporation) was classified using an elbow jet classifier (product name: EJ-PURO, manufactured by Nippon Steel Mining Co., Ltd.). This yielded Classified Carbon Black 1 (Classified CB1) with a volume average particle size of 10 nm, and Classified Carbon Black 3 (Classified CB3) with a volume average particle size of 9 nm.

[0090] <Carbon Black (CB) Adjustment Example 2> Thermax N990 (manufactured by Cancarb, pH 11.0, ash 0.05%, DBP oil absorption 39cm) 3Classification was performed using an elbow jet classifier (product name: EJ-PURO, manufactured by Nippon Steel Mining Co., Ltd.) with a volume-average particle size of 280 nm (Classified Carbon Black 2, Classified CB2) and Classified Carbon Black 4,

[0091] (Example 1) (Support) 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) 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 the cylinder, which was then used as the support.

[0092] (Formation of the underlayer) A mixture was obtained by mixing 10 parts by mass of carbon black #30 (product name: General-purpose color (RCF) #30, pH 8, volatile content 0.6% by mass, DBP oil absorption (granular): 104 ml / 100 g, volume average particle size: 30 nm, manufactured by Mitsubishi Chemical Corporation), 23 parts by mass of blocked isocyanate (product name: TPA-B80E, 80% solution, manufactured by Asahi Kasei Corporation), 23 parts by mass of butyral resin (product name: Esrec BM-1, manufactured by Sekisui Chemical Co., Ltd.), and 78 parts by mass of methyl ethyl ketone / 155 parts by mass of 1-butanol. 22.5 parts by mass of perinone compound (1-13) and 22.5 parts by mass of perinone compound (2-13) were mixed into the obtained mixture, and the mixture was placed in a vertical sand mill using 180 glass beads with an average particle size of 1 mm. Dispersion treatment was carried out for 4 hours at a rotation speed of 1500 rpm (peripheral speed of 5.5 m / s) in an atmosphere of 23 ± 3 °C to obtain a dispersion. To this dispersion, 0.01 parts of silicone oil (product name: SH28 PAINT ADDITIVE, manufactured by Toray Dow Corning) was added as a leveling agent. The mixture was then stirred to prepare a coating solution for the undercoat layer. The obtained undercoating solution was applied to the support by immersion to form a coating film, and the coating film was dried at 160°C for 30 minutes to form an undercoat with a thickness of 15 μm.

[0093] (Formation of a charge generation layer) 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 formula (A) were added to a solution prepared by dissolving 2 parts of polyvinyl butyral (trade name: Esrec BX-1, manufactured by Sekisui Chemical Co., Ltd.) in 100 parts of cyclohexanone. These were placed in a sand mill using 1 mm diameter glass beads and dispersed for 1 hour in an atmosphere of 23±3°C. [ka] After dispersion treatment, a coating solution for the charge generation layer was prepared by adding 100 parts of ethyl acetate. This charge generation layer coating solution was applied by immersion onto the undercoat layer formed above to form a coating film, and the resulting coating film was dried at 90°C for 10 minutes to form a charge generation layer with a thickness of 0.19 μm.

[0094] (Formation of a charge transport layer) Next, 8 parts of the amine compound (hole transporter) shown in the following structural formula (7), [ka] Furthermore, 10 parts of polyester resin (P1) having repeating structural units shown in formulas (8) and (9) below in a molar ratio of 5 / 5, and having a weight-average molecular weight (Mw) of 100,000, [ka] [ka] A coating solution for the hole transport layer was prepared by dissolving it in a mixed solvent of 40 parts dimethoxymethane and 60 parts chlorobenzene. This hole transport layer coating solution was applied by immersion onto the charge generation layer formed above, and the resulting coating film was dried at 120°C for 40 minutes to form a charge transport layer with a thickness of 15 μm. In this way, an electrophotographic photoreceptor having an undercoat layer, a charge generation layer, and a charge transport layer in that order was fabricated on a support.

[0095] (Examples 2-29) An electrophotographic photoreceptor having an undercoat layer, a charge generation layer, and a charge transport layer in that order on a support was fabricated in the same manner as in Example 1, except that the type and amount of perinone compound used as a charge transport compound, the type and amount of carbon black used, and the amount of resin used were changed according to the conditions described in Table 3.

[0096] (Comparative Example 1) An electrophotographic photoreceptor having a base layer, a charge generation layer, and a charge transport layer in that order on a support was fabricated in the same manner as in Example 1, except that the base layer was modified as follows.

[0097] (Formation of the underlayer) Blocked isocyanate (product name: TPA-B80E, 80% solution, manufactured by Asahi Kasei Corporation) 35 parts by mass, butyral resin (product name: Esrec BM-1, manufactured by Sekisui Chemical Co., Ltd.) 35 parts by mass, N,N-diethylaminobenzaldehyde represented by the comparative compound (3-1) below, N,N-diphenylhydrazone represented by the comparative compound (3-2) below 20 parts by mass, and carbon black #30 (product name: General-purpose color (RCF) 10 parts by mass of (#30, pH 8, volatile content 0.6% by mass, DBP oil absorption (granular): 104 ml / 100 g, volume average particle size: 30 nm, manufactured by Mitsubishi Chemical Corporation) were mixed with 78 parts by mass of methyl ethyl ketone and 155 parts by mass of 1-butanol. The mixture was placed in a vertical sand mill using 180 parts of glass beads with an average particle size of 1 mm and dispersed for 4 hours at a rotation speed of 1500 rpm (peripheral speed 5.5 m / s) in an atmosphere of 23 ± 3 °C to obtain a dispersion. [ka] [ka] To this dispersion, 0.01 parts of silicone oil (product name: SH28 PAINT ADDITIVE, manufactured by Toray Dow Corning) was added as a leveling agent. The mixture was then stirred to prepare a coating solution for the undercoat layer. The obtained undercoat coating solution was applied by immersion onto the support used in Example 1 to form a coating film, and the coating film was dried at 100°C for 60 minutes to form an undercoat layer with a thickness of 15 μm.

[0098] (Comparative Example 2) An electrophotographic photoreceptor having a base layer, a charge generation layer, and a charge transport layer in that order on a support was fabricated in the same manner as in Example 1, except that the base layer was modified as follows.

[0099] (Formation of the underlayer) 30 parts by mass of blocked isocyanate (product name: TPA-B80E, 80% solution, manufactured by Asahi Kasei Corporation) and 30 parts by mass of butyral resin (product name: Esrec BM-1, manufactured by Sekisui Chemical Co., Ltd.) were dissolved in 78 parts by mass of methyl ethyl ketone and 155 parts by mass of 1-butanol. To this solution, 7.5 parts by mass of strontium titanate particles (average primary particle size 100 nm) and 45 parts by mass of perinone compound (1-1) were mixed and dispersed in a vertical sand mill using 180 parts of glass beads with an average particle size of 1 mm for 4 hours at a rotation speed of 1500 rpm (peripheral speed 5.5 m / s) in an atmosphere of 23 ± 3 °C to obtain a dispersion. To this dispersion, 0.01 parts of silicone oil (product name: SH28 PAINT ADDITIVE, manufactured by Toray Dow Corning) was added as a leveling agent. The mixture was then stirred to prepare a coating solution for the undercoat layer. The obtained undercoat coating solution was applied by immersion onto the support used in Example 1 to form a coating film, and then dried and cured at 160°C for 60 minutes to form an undercoat layer with a thickness of 20 μm.

[0100] (Comparative Example 3) An electrophotographic photoreceptor having a base layer, a charge generation layer, and a charge transport layer in that order on a support was fabricated in the same manner as in Example 1, except that the base layer was modified as follows.

[0101] (Formation of the lower layer) 30 parts by mass of blocked isocyanate (product name: TPA-B80E, 80% solution, manufactured by Asahi Kasei Corporation) and 30 parts by mass of butyral resin (product name: Esrec BM-1, manufactured by Sekisui Chemical Co., Ltd.) were dissolved in 78 parts by mass of methyl ethyl ketone and 155 parts by mass of 1-butanol. To this solution, 17 parts by mass of perinone compound (1-3), 17 parts by mass of perinone compound (2-3), and 20 parts by mass of alumina particles (manufactured by EM Japan, average primary particle size 200 nm) were mixed and dispersed in a vertical sand mill using 180 parts of glass beads with an average particle size of 1 mm for 4 hours at a rotation speed of 1500 rpm (peripheral speed 5.5 m / s) in an atmosphere of 23 ± 3 °C to obtain a dispersion. To this dispersion, 0.01 parts of silicone oil (product name: SH28 PAINT ADDITIVE, manufactured by Toray Dow Corning) was added as a leveling agent. The mixture was then stirred to prepare a coating solution for the undercoat layer. The obtained undercoat coating solution was applied by immersion onto the support used in Example 1 to form a coating film, and then dried and cured at 160°C for 60 minutes to form an undercoat layer with a thickness of 5 μm.

[0102] (Comparative Example 4) An electrophotographic photoreceptor having a base layer, a charge generation layer, and a charge transport layer in that order on a support was fabricated in the same manner as in Example 1, except that the base layer was modified as follows.

[0103] (Formation of the lower layer) 30 parts by mass of blocked isocyanate (product name: TPA-B80E, 80% solution, manufactured by Asahi Kasei Corporation) and 30 parts by mass of butyral resin (product name: Esrec BM-1, manufactured by Sekisui Chemical Co., Ltd.) were dissolved in 78 parts by mass of methyl ethyl ketone and 155 parts by mass of 1-butanol. 25 parts by mass of perinone compound (1-3) and 25 parts by mass of perinone compound (2-3) were mixed into this solution. The mixture was placed in a vertical sand mill using 180 glass beads with an average particle size of 1 mm and dispersed for 4 hours at a rotation speed of 1500 rpm (peripheral speed of 5.5 m / s) in an atmosphere of 23±3°C to obtain a dispersion. To this dispersion, 2 parts by mass of silicone resin particles (Tospar 145, manufactured by Momentive Performance Materials) and 0.01 parts of silicone oil (product name: SH28 PAINT ADDITIVE, manufactured by Toray Dow Corning) as a leveling agent were added. The mixture was then stirred to prepare a coating solution for the undercoat layer. The obtained undercoat coating solution was applied by immersion onto the support used in Example 1 to form a coating film, and then dried and cured at 160°C for 60 minutes to form an undercoat layer with a thickness of 7 μm.

[0104] <Evaluation of electrophotographic photoconductors> The electrophotographic photoreceptors prepared by the methods described in Examples 1 to 29 and Comparative Examples 1 to 4 were evaluated using the following methods.

[0105] (Evaluation of crack formation in the undercoat during prolonged use) In this evaluation, the electrophotographic photoconductor was mounted in a Canon imageRUNNER ADVANCE C5255 (registered trademark) multifunction printer. More specifically, the drum cartridge containing the electrophotographic photoconductor to be evaluated was mounted in a cyan station for evaluation. An electrophotographic apparatus equipped with the electrophotographic photoreceptor to be evaluated under normal temperature and humidity conditions of 23°C / 50%RH was subjected to repeated use of the electrophotographic photoreceptor through a paper feed durability test. 50,000 images of a single cyan color character with a print density of 1% were repeatedly formed on A4 size plain paper. The surface of an electrophotographic photoreceptor with depressions after 50,000 repeated image formations was observed using a laser microscope (Keyence Corporation, product name: VK-9500) with a 50x lens to determine the depressions and flat areas on the surface of the electrophotographic photoreceptor. During observation, the microscope was adjusted so that there was no tilt in the longitudinal direction of the electrophotographic photoreceptor, and in the circumferential direction, the focus was set to the apex of the arc of the electrophotographic photoreceptor. Images were then taken from a 1.5 cm (3 cm long) area around the longitudinal center of the electrophotographic photoreceptor, and these images were stitched together using an image stitching application to obtain information about the entire surface of the electrophotographic photoreceptor. The obtained results were then filtered using the included image analysis software, selecting the image processing height data and using the median filter type. Based on the results obtained, the locations and number of cracks on the surface of the electrophotographic photoreceptor with recesses after 50,000 repeated image formations were confirmed. The evaluation was performed according to the following criteria. In this invention, the following ranks were set and judged as follows. A: No cracks were found. B: Number of cracks: 1-5 (no problem in actual use) C: Number of cracks: 6-10 (no problem in actual use) D: Number of cracks found: 11 or more The results of this evaluation are shown in Table 3.

[0106] (Evaluation of potential fluctuations during repeated use) For this evaluation, we used the imageRUNNER ADVANCE C5255 (registered trademark) multifunction printer manufactured by Canon Inc. as the evaluation unit. The cyan developer cartridge was removed from the prepared evaluation machine, and a potential measuring device was attached to it. The potential measuring device is a device in which a potential measuring probe is placed at the development position of the developer cartridge. The potential measuring probe was positioned in the center in the direction of the busbar of the electrophotographic photoreceptor. Using this evaluation machine, a drum cartridge with the electrophotographic photoreceptor to be evaluated attached was mounted on a cyan station, and the surface potential of the electrophotographic photoreceptor was measured. For the measurement, the charging conditions were first adjusted so that the dark area potential was -600V for the initial electrophotographic photoreceptor, and the laser power was adjusted so that the bright area potential was -250V. Next, the potential measurement probe was removed, and the drum cartridge, which had the developing cartridge and the electrophotographic photoreceptor to be evaluated attached, was mounted on the cyan station. A paper feed durability test was then performed, and the potential of the electrophotographic photoreceptor was measured after durability testing. An electrophotographic apparatus equipped with the electrophotographic photoreceptor to be evaluated underwent repeated use of the electrophotographic photoreceptor in a paper-feed durability test at a normal temperature and humidity environment of 23°C / 50%RH. Using A4-sized plain paper, 10,000 images of cyan monochrome text with a print density of 1% were repeatedly formed, and the potential of the electrophotographic photoreceptor was measured after durability testing. At that time, the charging conditions were adjusted so that the dark area potential was -600V, and the laser power was adjusted to match the laser output adjusted during the initial potential measurement, and the bright area potential was measured. The difference between the measured light-area potential after endurance testing and the initial light-area potential (-250V) was calculated and defined as the change in light-area potential, ΔVl. This ΔVl was evaluated according to the following evaluation ranks. In this invention, ranks A, B, and C represent levels where the effects of the present invention are achieved, with rank A being judged to be an excellent level. On the other hand, rank D was judged to be a level where the effects of the present invention are not achieved. A: When the change in bright area potential is within 5V B: When the change in bright area potential is greater than 5V but less than or equal to 10V C: When the change in bright area potential is greater than 10V and within 20V. D: When the change in bright area potential is greater than 20V The results of this evaluation are shown in Table 1.

[0107] [Table 1]

[0108] As shown in Table 1, in the electrophotographic photoreceptor of the present invention, and in the process cartridge and electrophotographic apparatus using the electrophotographic photoreceptor of the present invention, it can be seen that good results are obtained in suppressing the occurrence of cracks during long-term use and suppressing potential fluctuations during repeated use. On the other hand, as in the comparative example, when the undercoat layer does not contain the perinone compound and carbon black of the present invention, it can be seen that many cracks occur during long-term use, the potential fluctuation during repeated use is large, and the object of the present invention cannot be achieved.

[0109] The disclosure of this embodiment includes the following configurations and methods. (Configuration 1) An electrophotographic photoreceptor having a support, an undercoat layer, and a photosensitive layer in this order, where the undercoat layer contains at least one perinone compound selected from the group consisting of a compound represented by the following formula (1) and a compound represented by the following formula (2), and carbon black, An electrophotographic photoreceptor characterized by this. [Chemical formula] [Chemical formula] (In formula (1), R 11 ~R 18 , and in formula (2), R 21 ~R 28 each independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group, a substituted or unsubstituted alkoxycarbonyl group, and among the groups of R 11 ~R 14 , R 15 ~R 18 , R 21 ~R 24 and R 25 ~R 28 in each group, adjacent groups may be linked together to jointly form a ring.) (Configuration 2) The electrophotographic photoreceptor according to configuration 1, wherein the content of the perinone compound in the undercoat layer is 30% by mass or more and 60% by mass or less relative to the total mass of the undercoat layer. (Composition 3) The electrophotographic photoreceptor according to configuration 1 or 2, wherein the carbon black content in the undercoat layer is 0.5% by mass or more and 20% by mass or less relative to the total mass of the undercoat layer. (Composition 4) An electrophotographic photoreceptor according to any one of configurations 1 to 3, wherein the average primary particle size of the carbon black is 10 nm or more and 200 nm or less. (Composition 5) An electrophotographic photoreceptor according to any one of configurations 1 to 4, wherein the carbon black content in the undercoat layer is 1% by mass or more and 70% by mass or less relative to the mass of the perinone compound. (Composition 6) The electrophotographic photoreceptor according to any one of configurations 1 to 5, wherein the undercoat contains, as the perinone compound, at least one perinone compound selected from the group consisting of the compound represented by the following formula (3) and the compound represented by the following formula (4). [ka] [ka] (R in equation (3)) 31 and R 32 , and R in equation (4) 41 and R 42 Each of these independently represents a branched alkyl group with a total number of carbon atoms between 3 and 10. (Composition 7) The electrophotographic photoreceptor according to any one of configurations 1 to 6, wherein the undercoat contains, as the perinone compound, at least one perinone compound selected from the group consisting of the compound represented by the following formula (5) and the compound represented by the following formula (6). [ka] [ka] (R in equation (5)) 51 , R 52 , R 53 , R 54 , R 55 and R 56 , and in equation (6), R 61 , R 62 , R 63 , R 64 , R 65 and R 66 These independently represent a methyl group, an ethyl group, or a propyl group. (Composition 8) The electrophotographic photoreceptor according to any one of configurations 1 to 7, wherein the undercoat layer is a layer formed by drying and / or curing a coating film of an undercoat coating liquid containing the perinone compound and the carbon black. (Composition 9) A process cartridge that integrally supports an electrophotographic photoreceptor as described in any one of configurations 1 to 8, and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, and is detachably attached to the main body of an electrophotographic apparatus. (Composition 10) An electrophotographic photoreceptor according to any one of configurations 1 to 8, and an electrophotographic apparatus having a charging means, an exposure means, a developing means, and a transfer means. (Method 1) A method for manufacturing an electrophotographic photoreceptor having a support, an undercoat layer, and a photosensitive layer in this order, The manufacturing method is A step of preparing a coating solution for the undercoat layer, and The process includes the steps of forming a coating film of the undercoat liquid, and forming the undercoat by drying and / or curing the coating film, The coating liquid for the undercoat layer is At least one perinone compound selected from the group consisting of the compound represented by formula (1) below and the compound represented by formula (2) below, Carbon Black A method for producing an electrophotographic photoreceptor, characterized by containing the following: [ka] [ka] (R in equation (1)) 11 ~R 18 , and R in equation (2) 21 ~R 28 Each of these independently represents a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, a substituted or unsubstituted aryl group, a substituted or unsubstituted aryloxy group, or a substituted or unsubstituted alkoxycarbonyl group, R 11 ~R 14 , R 15 ~R 18 , R 21 ~R 24 and R 25 ~R 28 Within each group, adjacent groups may be linked together to form a ring. [Explanation of Symbols]

[0110] 101 Support 102 Conductive layer 103 Lower layer 104 Charge generation layer 105 Charge transport layer 106 Protective layer 107 Photosensitive layer 1. Electrophotographic photoreceptor 2 axes 3. Charging means 4 Exposure light 5. Developing means 6. Transfer means 7 Transfer material 8 Fixing means 9. Cleaning methods 10 Pre-exposure light 11 Process Cartridges 12 Guidance methods

Claims

1. An electrophotographic photoreceptor having a support, an undercoat, and a photosensitive layer in this order, The lower layer is Perinone compounds, and Carbon black, It contains, The perinone compound is the compound represented by the following formula (5) and the compound represented by the following formula (6), The content of the perinone compound in the underlayer is 30% by mass or more and 60% by mass or less relative to the total mass of the underlayer. The carbon black content in the undercoat is 0.5% by mass or more and 20% by mass or less relative to the total mass of the undercoat. The carbon black content in the undercoat is 1% by mass or more and 70% by mass or less relative to the perinone compound content in the undercoat. An electrophotographic photoreceptor characterized by the following features. 【Chemistry 1】 【Chemistry 2】 (In formula (5), R 51 to R 56 and in formula (6), R 61 to R 66 each independently represent a methyl group, an ethyl group, or a propyl group.)

2. The electrophotographic photoreceptor according to claim 1, wherein the compound represented by formula (5) is the compound represented by the following formula (1-13), and the compound represented by formula (6) is the compound represented by the following formula (2-13). 【Transformation 3】 【Chemistry 4】

3. The electrophotographic photoreceptor according to claim 1, wherein the average primary particle size of the carbon black is 10 nm or more and 200 nm or less.

4. The electrophotographic photoreceptor according to claim 1, wherein the undercoat layer is a layer formed by drying and / or curing a coating film of an undercoat coating liquid containing the perinone compound and the carbon black.

5. A process cartridge that integrally supports an electrophotographic photoreceptor according to any one of claims 1 to 4 and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, and is detachably attached to the main body of an electrophotographic apparatus.

6. An electrophotographic photoreceptor according to any one of claims 1 to 4, and an electrophotographic apparatus having a charging means, an exposure means, a developing means, and a transfer means.

7. A method for manufacturing an electrophotographic photoreceptor having a support, an undercoat layer, and a photosensitive layer in this order, The manufacturing method is A step of preparing a coating solution for the undercoat layer, and A step of forming the undercoat by forming a coating film of the undercoat liquid and drying and / or curing the coating film, It has, The coating liquid for the undercoat layer is Perinone compounds, and Carbon black, It contains, The perinone compound is the compound represented by the following formula (5) and the compound represented by the following formula (6), The content of the perinone compound in the underlayer is 30% by mass or more and 60% by mass or less relative to the total mass of the underlayer. The carbon black content in the undercoat is 0.5% by mass or more and 20% by mass or less relative to the total mass of the undercoat. A method for manufacturing an electrophotographic photoreceptor, characterized in that the carbon black content in the undercoat layer is 1% by mass or more and 70% by mass or less relative to the perinone compound content in the undercoat layer. 【Transformation 5】 【Transformation 6】 (In formula (5), R 51 to R 56 and in formula (6), R 61 to R 66 each independently represent a methyl group, an ethyl group, or a propyl group.)

8. The method for producing an electrophotographic photoreceptor according to claim 7, wherein the compound represented by formula (5) is the compound represented by the following formula (1-13), and the compound represented by formula (6) is the compound represented by the following formula (2-13). 【Transformation 7】 【Transformation 8】

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