Electrophotographic photoreceptor, process cartridge, and electrophotographic apparatus

Abstract

To provide an electrophotographic photoreceptor that can prevent unevenness in a surface direction of an output image through repeated image formation.SOLUTION: In an electrophotographic photoreceptor having a cylindrical support and a photosensitive layer formed on the support, the support contains at least one of aluminum and an aluminum alloy. When A(μm2) is the area at the maximum frequency calculated from an area distribution curve of crystal grains of aluminum on a surface of the support, and B(μm2) is the half width of the maximum peak in the area distribution curve, the support satisfies the following formula (1). (1) B / A≤1.0.SELECTED DRAWING: Figure 1

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] In recent years, the users of electrophotographic devices have become more diverse, and there is a growing need for higher image quality in the output images. Patent Document 1 describes a technique for improving image quality in which the stress value of a conductive support is set to a range of -30 MPa to 5 MPa. Patent Document 2 describes a technique for improving image quality from the standpoint of precision in which an aluminum alloy tube is heated to 190°C to 550°C before machining. Furthermore, Patent Document 3 describes a technique for setting the average area of ​​the crystal grains of an aluminum alloy having a specific composition to 3 μm 2 More than 100μm 2 The following technologies are described. [Prior art documents] [Patent Documents]

[0003] [Patent Document 1] International Publication No. 2019 / 077705 [Patent Document 2] Japanese Patent Publication No. 2009-150958 [Patent Document 3] Japanese Patent Publication No. 2017-111409 [Overview of the project] [Problems that the invention aims to solve]

[0004] According to the inventors' research, the electrophotographic photoreceptors described in Patent Documents 1 to 3 have the problem that repeated image formation tends to cause surface-direction unevenness in the output image. Therefore, the object of the present invention is to provide an electrophotographic photoreceptor that can suppress surface-direction unevenness in the output image through repeated image formation. [Means for solving the problem]

[0005] The above object is achieved by the following present invention. That is, in an electrophotographic photoreceptor having a cylindrical support and a photosensitive layer formed on the support, the support is made of It contains silicon at a concentration of 0.6% by mass or less, iron at a concentration of 0.7% by mass or less, copper at a concentration of 0.05% to 0.2% by mass, manganese at a concentration of 1.0% to 1.5% by mass, and zinc at a concentration of 0.1% by mass or less, with the remainder being... aluminum and Contains impurities an aluminum alloy A support comprising the above, or a support comprising an aluminum alloy containing 0.2% to 0.6% by mass of silicon, 0.35% by mass or less of iron, 0.1% by mass or less of copper, 0.1% by mass or less of manganese, 0.45% to 0.9% by mass of magnesium, 0.1% by mass or less of chromium, 0.1% by mass or less of zinc, and 0.1% by mass or less of titanium, with the remainder being aluminum and impurities. , and when the area at the maximum frequency calculated from the area distribution curve of the crystal grains of aluminum on the surface of the support is defined as A (μm 2 ), and the half-value width of the maximum peak in the area distribution curve is defined as B (μm 2 ), the support satisfies the following formula (1) 、 B / A≦1.0 formula (1) An electrophotographic photoreceptor characterized by the following features.

Advantages of the Invention

[0006] It is possible to provide an electrophotographic photoreceptor capable of suppressing unevenness in the plane direction of the output image through repeated image formation.

Brief Description of the Drawings

[0007] [Figure 1] (a) Schematic diagram of an observation screen when the surface of the support of the electrophotographic photoreceptor of the present invention is observed with an electron microscope. (b) Diagram illustrating the area distribution curve of crystal grains. [Figure 2] An example of the schematic configuration of the electrophotographic apparatus of the present invention is shown.

Embodiments for Carrying Out the Invention

[0008] Hereinafter, the present invention will be described in detail with reference to preferred embodiments. As a result of investigations by the present inventors, in the electrophotographic photoreceptor of the prior art, when repeated image formation is performed, slight variations occur in the potential of the exposed portion due to minute resistance unevenness in the conductive aluminum support itself, and for this reason, there is a possibility that unevenness in the plane direction occurs in the output image. To solve this problem, the inventors of the present invention examined the crystal grains on the surface of the aluminum support.

[0009] As a result of the examination, in an electrophotographic photoreceptor having a cylindrical support and a photosensitive layer formed on the support, the support contains at least one of aluminum and an aluminum alloy, and the area at the maximum frequency calculated from the area distribution curve of the crystal grains of aluminum on the surface of the support is A (μm 2 ), and when the half-value width of the maximum peak in the area distribution curve is B (μm 2 ), it has been found that when the support satisfies the following formula (1), the unevenness in the plane direction of the output image generated in the conventional electrophotographic photoreceptor can be reduced. B / A≦1.0 ···(1)

[0010] The inventors of the present invention consider the mechanism for reducing the unevenness in the plane direction of the output image as follows based on the configuration of the present invention. The crystal grains of aluminum usually have random sizes. The inventors of the present invention推测 that due to the size of the crystal grains of aluminum, the ease of electron flow in the crystal is slightly different, that is, the smaller the crystal grains, the more affected by the grain boundaries, and thus the more difficult it is for electrons to flow.

[0011] In the aluminum support used in the conventional electrophotographic photoreceptor, the crystal grains of aluminum have random sizes. Therefore, the ease of electron flow is different for each crystal grain. By repeatedly performing image formation, the difference in the ease of electron flow for each crystal grain becomes prominent, generating unevenness in the plane direction of the potential. Since image formation is performed according to the potential, the magnitude of the unevenness of the potential and the output image is in a proportional relationship. As a result, it is considered that unevenness in the plane direction is generated in the output image. Therefore, it is believed that by making the size of the aluminum crystal grains forming the surface of the aluminum support more uniform, the current flowing through the aluminum support can be made more uniform, improving potential unevenness and thus reducing planar unevenness in the output image. The uniformity of the size of the aluminum crystal grains forming the surface of the aluminum support can be determined from the area of ​​the aluminum crystal grains. As described above, the effects of the present invention can be achieved through the synergistic effects of each component.

[0012] [Electrophotographic photoconductor] The electrophotographic photoreceptor of the present invention is characterized by having a support whose surface is formed of at least one of aluminum and an aluminum alloy, and a photosensitive layer. A film of aluminum hydroxide and / or aluminum oxide may be formed on the surface of the support. One method for manufacturing the electrophotographic photoreceptor of the present invention is to prepare coating solutions for each layer, as described later, apply them in the desired order, and then dry them. Methods for applying the coating solutions include immersion coating, spray coating, inkjet coating, roll coating, die coating, blade coating, curtain coating, wire bar coating, and ring coating. Among these, immersion coating is preferred from the viewpoint of efficiency and productivity. The support structure and each layer will be described below.

[0013] <Support> The electrophotographic photoreceptor of the present invention has a cylindrical support whose surface is formed of at least one of aluminum and an aluminum alloy. Furthermore, the surface of the support may be subjected to hot water treatment, blasting, cutting, or the like.

[0014] (1) Regarding the area distribution curve of crystal grains A(μm) is the area of ​​aluminum crystal grains at maximum frequency, calculated from the area distribution curve of aluminum crystal grains on the support surface. 2 ), the full width at half maximum of the maximum peak in the area distribution curve of aluminum crystal grains is B (μm). 2When [condition], B / A is 1.0 or less. From the viewpoint of making the ease of electron flow uniform for each crystal grain, it is preferable that B / A is 0.7 or less. Furthermore, when B / A is 0.5 or less, the effects of the present invention can be obtained better.

[0015] (2) Regarding the average area of crystal grains The average area of aluminum crystal grains is preferably 10 μm 2 or more. When the average area of aluminum crystal grains is 10 μm 2 or more, the ease of electron flow is less affected by grain boundaries, and the occurrence of initial charge retention on the support can be suppressed. As a result, short-term potential fluctuations can be reduced.

[0016] (Method for measuring the area of crystal grains) The measurement of the area of crystal grains can be performed as follows, for example. The area of crystal grains can be observed and measured with an electron microscope (for example, the VE series manufactured by Keyence Corporation, etc.). At positions 40 mm from both ends in the axial direction of the end of the photoreceptor and at the central position in the axial direction of the photoreceptor, for 4 locations (a total of 4×3 = 12 locations) every 90 degrees in the circumferential direction, a 10 mm square section is cut out together with the support. As the ends of the photoreceptor, specifically, when the length of the support is 297 mm, positions 40 mm, 18.5 mm, 8.5 mm, etc. from both ends in the axial direction of the photoreceptor can be mentioned. The protective layer is removed by polishing the section with a polishing sheet, and the photosensitive layer is removed using methyl ethyl ketone. Then, the surface of the support is exposed and mirror-finished by buff polishing. Next, a sample for measuring the area of crystal grains is obtained by immersing the section in an aqueous sodium hydroxide solution for 1 minute. A 100 μm square area of ​​the surface of the above sample is observed using an electron microscope, and the area of ​​the crystal grains is calculated using the standard image processing software. Since crystal grains of aluminum hydroxide and / or aluminum oxide are present on the sample surface, the observed crystal grains may be these crystal grains. However, because the film of aluminum hydroxide and / or aluminum oxide on the sample surface is very thin, the electron beam can penetrate it during electron microscope observation, allowing the observation of aluminum crystal grains. Therefore, in this invention, the aluminum crystal grains include not only aluminum crystal grains but also aluminum hydroxide and aluminum oxide crystal grains. At this stage, any crystal grains that are not fully visible within the observation screen, as indicated by the diagonal lines in Figure 1(a), are manually excluded.

[0017] (Method for creating area distribution curves of crystal grains) First, calculate the average area of ​​the crystal grains observed in the samples obtained from the 12 locations mentioned above. Then, calculate the frequency of the crystal grain area in increments of 1 / 20 of the average area to create a crystal grain area distribution. Specifically, calculate the frequency of the crystal grain area in increments of 1 / 20 of the average area, moving toward the smaller and larger areas around the average area, to create a crystal grain area distribution. For example, if the average area of ​​the crystal grain is 50 μm 2 In that case, 50 μm 2 With the center as the edge, towards the smaller and larger areas, 2.5 μm 2 The frequency of the crystal grain area is calculated at each step, and the area distribution curve shown in Figure 1(b) is created. The area distribution curve shown in Figure 1(b) is a normal distribution curve that best fits the frequency of the crystal grain area. The area at the highest frequency, calculated from this area distribution curve, is A(μm). 2 Let B (μm) be the range of the area where the maximum frequency in the area distribution curve is half the value (width on the horizontal axis), i.e., the half-width of the peak at the maximum value in the area distribution curve (half-width of the peak top of the normal distribution curve). 2 )

[0018] (3) Regarding aluminum alloys When the support material contains an aluminum alloy, 3000 series aluminum alloys and 6000 series aluminum alloys are preferred. For example, a 3000 series aluminum alloy is the JIS designated 3003 alloy, specifically an aluminum alloy containing 0.6% by mass or less of silicon, 0.7% by mass or less of iron, 0.05% to 0.2% by mass of copper, 1.0% to 1.5% by mass of manganese, and 0.1% by mass or less of zinc, with the remainder being aluminum and impurities. Furthermore, as an example of a 6000 series aluminum alloy, there is the JIS designated 6063 alloy, specifically an aluminum alloy containing 0.2% to 0.6% by mass of silicon, 0.35% or less by mass of iron, 0.1% or less by mass of copper, 0.1% or less by mass of manganese, 0.45% to 0.9% by mass of magnesium, 0.1% or less by mass of chromium, 0.1% or less by mass of zinc, and 0.1% or less by mass of titanium, with the remainder being aluminum and impurities. Such a 3000 series aluminum alloy or 6000 series aluminum alloy is preferable for controlling the crystal area distribution of the crystal grains.

[0019] (4) Regarding the manufacturing method of the support The method for manufacturing the support is not particularly limited, as long as the manufactured support satisfies the requirements of the present invention. A method for manufacturing a support includes, for example, a step of preparing aluminum or a specific aluminum alloy; a first step of obtaining a molded body by hot extrusion; a second step of subjecting the molded body obtained in the first step to cold drawing; a third step of annealing after the second step; and a step of cutting the surface after the third step. In the above method, the area of ​​the crystal grains can be controlled by the heating time, temperature, holding time, and cooling time during the third step of annealing. In particular, setting the annealing temperature to 405-450°C can ensure a uniform grain area distribution. Furthermore, since the grain area changes depending on the heating and cooling rates, it is preferable to control the heating rate to 40°C / min or less and the cooling rate to 5°C / min or less. To ensure sufficient recrystallization, the maintenance time should preferably be 2 hours or more. Furthermore, since thermal history is important for controlling the area of ​​the crystal grains, it is preferable to manufacture the support by annealing the material that has gone through the first and second steps described above.

[0020] <Conductive layer> In the electrophotographic photoreceptor of the present invention, a conductive layer may be provided on the support. By providing a conductive layer, scratches and irregularities on the surface of the support can be concealed and light reflection on the surface of the support can be controlled. Preferably, the conductive layer contains conductive particles and a resin.

[0021] Examples of conductive particle materials 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, and bismuth oxide. Examples of metals include aluminum, nickel, iron, nichrome, copper, zinc, and silver. Among these, it is preferable to use metal oxides as conductive particles, and it is more preferable to use titanium oxide, tin oxide, or zinc oxide. When using metal oxides as conductive particles, the surface of the metal oxide may be treated with a silane coupling agent or doped with elements such as phosphorus or aluminum, or their oxides. Furthermore, the conductive particles may have a laminated structure comprising core material particles and a coating layer covering those particles. Examples of core material particles include titanium oxide, barium sulfate, and zinc oxide. Examples of the coating layer include metal oxides such as tin oxide. Furthermore, when using metal oxides as conductive particles, their volume-average particle diameter is preferably 1 nm or more and 500 nm or less, and more preferably 3 nm or more and 400 nm or less.

[0022] Examples of resins include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenolic resin, and alkyd resin. Furthermore, the conductive layer may further contain silicone oil, resin particles, a concealing agent such as titanium dioxide, etc.

[0023] The average thickness of the conductive layer is preferably 1 μm or more and 50 μm or less, and particularly preferably 3 μm or more and 40 μm or less.

[0024] A conductive layer can be formed by preparing a coating solution for a conductive layer containing the above-mentioned materials and solvents, forming a coating film, 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. Methods for dispersing conductive particles in the coating solution for a conductive layer include using a paint shaker, sand mill, ball mill, or liquid impaction type high-speed disperser.

[0025] <Underlayer> In the electrophotographic photoreceptor of the present invention, an undercoat layer may be provided on the support or conductive layer. By providing an undercoat layer, the adhesion function between layers is enhanced, and a charge injection blocking function can be provided. The undercoat layer preferably contains a resin. Alternatively, the undercoat layer may be formed as a cured film by polymerizing a composition containing a monomer having polymerizable functional groups. Examples of resins include polyester resins, polycarbonate resins, polyvinyl acetal resins, acrylic resins, epoxy resins, melamine resins, polyurethane resins, phenolic resins, polyvinylphenol resins, alkyd resins, polyvinyl alcohol resins, polyethylene oxide resins, polypropylene oxide resins, polyamide resins, polyamic acid resins, polyimide resins, polyamide-imide resins, and cellulose resins. Examples of polymerizable functional groups found in monomers having 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.

[0026] Furthermore, the undercoat layer may further contain electron transport materials, metal oxides, metals, conductive polymers, etc., for the purpose of improving electrical properties. Among these, electron transport materials and metal oxides are preferred. Examples of electron transport materials include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienylidene compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, aryl halides, silole compounds, and boron-containing compounds. An electron transport material having polymerizable functional groups may be used as the electron transport material, and a base layer may be formed as a cured film by copolymerizing it with the above-mentioned monomers having polymerizable functional groups. Examples of metal oxides include indium tin oxide, tin oxide, indium oxide, titanium oxide, zinc oxide, aluminum oxide, and silicon dioxide. Examples of metals include gold, silver, and aluminum. Furthermore, the underlayer may contain additional additives.

[0027] The average thickness of the undercoat layer is preferably 0.1 μm or more and 50 μm or less, more preferably 0.2 μm or more and 40 μm or less, and particularly preferably 0.3 μm or more and 30 μm or less.

[0028] The undercoat can be formed by preparing an undercoat coating solution containing the above-mentioned materials and solvents, forming a coating film, and then drying and / or curing it. Examples of solvents used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0029] <Photosensitive layer> In the electrophotographic photoreceptor of the present invention, the photosensitive layer may be mainly (1) a stacked photosensitive layer or (2) a single-layer photosensitive layer. (1) The stacked photosensitive layer has a charge generating layer containing a charge generating material and a charge transport layer containing a charge transport material. (2) The single-layer photosensitive layer has a photosensitive layer containing both a charge generating material and a charge transport material.

[0030] (1) Stacked photosensitive layer The stacked photosensitive layer comprises a charge generation layer and a charge transport layer.

[0031] (1-1) Charge generation layer The charge generation layer preferably contains a charge generation material and a resin.

[0032] Examples of charge-generating materials include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, and phthalocyanine pigments. Among these, azo pigments and phthalocyanine pigments are preferred. Among phthalocyanine pigments, oxytitanium phthalocyanine pigments, chlorogallium phthalocyanine pigments, and hydroxygallium phthalocyanine pigments are preferred. The content of the charge generating material in the charge generating layer is preferably 40% to 85% by mass, and more preferably 60% to 80% by mass, relative to the total mass of the charge generating layer.

[0033] Examples of resins include polyester resin, polycarbonate resin, polyvinyl acetal resin, polyvinyl butyral resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenolic resin, polyvinyl alcohol resin, cellulose resin, polystyrene resin, polyvinyl acetate resin, and polyvinyl chloride resin. Among these, polyvinyl butyral resin is more preferred.

[0034] 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.

[0035] The average thickness of the charge generation layer is preferably 0.1 μm or more and 1 μm or less, and more preferably 0.15 μm or more and 0.4 μm or less.

[0036] 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 a coating film, 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.

[0037] (1-2) Charge transport layer The charge transport layer preferably contains a charge transport material and a resin.

[0038] Examples of charge transport materials include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these substances. Among these, triarylamine compounds and benzidine compounds are preferred. The content of the charge transport material in the charge transport layer is preferably 25% to 70% by mass, and more preferably 30% to 55% by mass, relative to the total mass of the charge transport layer.

[0039] Examples of resins include polyester resin, polycarbonate resin, acrylic resin, and polystyrene resin. Among these, polycarbonate resin and polyester resin are preferred. Polyarylate resin is particularly preferred among polyester resins. The content ratio (mass ratio) of the charge transport material to the resin is preferably 4:10 to 20:10, and more preferably 5:10 to 12:10.

[0040] Furthermore, the charge transport layer may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, lubrication agents, and wear resistance enhancers. Specifically, examples 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. The average thickness of the charge transport layer is preferably 5 μm to 50 μm, more preferably 8 μm to 40 μm, and particularly preferably 10 μm to 30 μm.

[0041] The charge transport layer can be formed by preparing a coating solution for the charge transport layer containing the above-mentioned materials and solvents, forming a coating film, and drying it. Examples of solvents used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, ether-based solvents or aromatic hydrocarbon-based solvents are preferred.

[0042] (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, and drying it. The charge generating substance, charge transporting substance, and resin are the same as the materials used in "(1) Multilayer Photosensitive Layer" described above.

[0043] <Protective layer> In the electrophotographic photoreceptor of the present invention, a protective layer may be provided on the photosensitive layer. Providing a protective layer can improve durability. The protective layer preferably contains conductive particles and / or charge transport material and a resin.

[0044] Examples of conductive particles include metal oxide particles such as titanium oxide, zinc oxide, tin oxide, and indium oxide.

[0045] Examples of charge transport materials include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these substances. Among these, triarylamine compounds and benzidine compounds are preferred.

[0046] Examples of resins include polyester resin, acrylic resin, phenoxy resin, polycarbonate resin, polystyrene resin, phenolic resin, melamine resin, and epoxy resin. Among these, polycarbonate resin, polyester resin, and acrylic resin are preferred.

[0047] Furthermore, the protective layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group. Examples of reactions in this case include thermal polymerization, photopolymerization, and radiation polymerization. Examples of polymerizable functional groups in monomers having a polymerizable functional group include acrylic groups and methacrylic groups. Materials with charge transport ability may be used as monomers having a polymerizable functional group.

[0048] The protective layer may contain additives such as antioxidants, UV absorbers, plasticizers, leveling agents, lubrication agents, and wear resistance enhancers. Specifically, examples 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.

[0049] The average thickness of the protective layer is preferably 0.5 μm to 10 μm, and more preferably 1 μm to 7 μm.

[0050] The protective layer can be formed by preparing a protective coating solution containing the above-mentioned materials and solvents, forming a coating film, and then drying and / or curing it. Examples of solvents used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, sulfoxide-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0051] [Process cartridges, electrophotographic equipment] The process cartridge of the present invention is characterized by integrally supporting the electrophotographic photoreceptor 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. Furthermore, the electrophotographic apparatus of the present invention is characterized by comprising an electrophotographic photoreceptor as described above, and at least one means selected from the group consisting of a charging means, an exposure means, a developing means, and a transfer means.

[0052] Figure 2 shows an example of a schematic configuration of an electrophotographic apparatus having a process cartridge equipped with an electrophotographic photoreceptor. The cylindrical electrophotographic photoreceptor 1 is rotated at a predetermined peripheral speed in the direction of the arrow around the axis 2. The surface of the electrophotographic photoreceptor 1 is charged to a predetermined positive or negative potential by the charging means 3. In the figure, a roller charging method using a roller-type charging member is shown, but other charging methods such as corona charging, proximity charging, and injection charging may 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. The electrostatic latent image formed on the surface of the electrophotographic photoreceptor 1 is developed with toner contained in the 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 with the transferred toner image is transported to a fixing means 8, undergoes toner image fixing processing, and is printed out outside the electrophotographic device. The electrophotographic device may have a cleaning means 9 for removing toner and other deposits remaining on the surface of the electrophotographic photoreceptor 1 after transfer. Furthermore, 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. The electrophotographic apparatus may also have a static elimination mechanism that removes static electricity from the surface of the electrophotographic photoreceptor 1 by pre-exposure light 10 from a pre-exposure means (not shown). In addition, 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.

[0053] The electrophotographic photoreceptor of the present invention can be used in laser beam printers, LED printers, photocopiers, facsimile machines, and multifunction devices thereof. [Examples]

[0054] 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.

[0055] [Method for preparing the support] The support was prepared using the following method.

[0056] (Example of manufacturing support A-1) A hot-extruded extruded tube made of JIS nominal 3003 alloy was cold-drawn to obtain a drawn tube with an outer diameter of 30.8 mm, an inner diameter of 28.5 mm, and a length of 370 mm. Next, the drawn tubes were placed in an electric furnace and annealed at a heating rate of 5°C / min at 450°C for 2.5 hours. After that, they were cooled at 1°C / min and removed after 24 hours. Details are shown in Table 1. After annealing, a mirror-finish machining process was performed on the surface to obtain a support A-1 with an outer diameter of 30.5 mm, an inner diameter of 28.5 mm, and a length of 370 mm. Elemental analysis of the drawn tubes used revealed that they contained 0.16 mass% silicon, 0.2 mass% iron, 0.08 mass% copper, 1.3 mass% manganese, and 0.02 mass% zinc, with the remainder being an aluminum alloy containing aluminum and impurities.

[0057] (Manufacturing examples of supports A-2 to A-13) In the example of manufacturing support A-1, the support was prepared in the same manner as in the example of manufacturing support A-1, except that the same drawn tube was used and the annealing conditions were changed as shown in Table 1. The obtained supports were designated as supports A-2 to A-13.

[0058] (Example of manufacturing support A-14) A hot-extruded extruded tube made of JIS nominal 3003 alloy was cold-drawn to obtain a drawn tube with an outer diameter of 30.8 mm, an inner diameter of 28.5 mm, and a length of 370 mm. Next, the drawn tubes were placed in an electric furnace and annealed at a heating rate of 5°C / min at 435°C for 2.5 hours. After that, they were cooled at 1°C / min and removed after 24 hours. Details are shown in Table 1. After annealing, a mirror-finish machining process was performed on the surface to obtain a support A-14 with an outer diameter of 30.5 mm, an inner diameter of 28.5 mm, and a length of 370 mm. Elemental analysis of the drawn tubes used revealed that they contained 0.5 mass% silicon, 0.6 mass% iron, 0.15 mass% copper, 1.2 mass% manganese, and 0.08 mass% zinc, with the remainder being an aluminum alloy containing aluminum and impurities.

[0059] (Example of manufacturing support B-1) A hot-extruded extruded tube made of JIS designated 6063 alloy was cold-drawn to obtain a drawn tube with an outer diameter of 30.8 mm, an inner diameter of 28.5 mm, and a length of 370 mm. Next, the drawn tubes were placed in an electric furnace and annealed at a heating rate of 5°C / min at 450°C for 2.5 hours. After that, they were cooled at 1°C / min and removed after 24 hours. Details are shown in Table 1. After annealing, a mirror-finish machining of the surface was performed to obtain support B-1 with an outer diameter of 30.5 mm, an inner diameter of 28.5 mm, and a length of 370 mm. Elemental analysis of the drawn tube used revealed that it contained 0.5 mass% silicon, 0.3 mass% iron, 0.07 mass% copper, 0.08 mass% manganese, 0.7 mass% magnesium, 0.04 mass% chromium, 0.08 mass% zinc, and 0.06 mass% titanium, with the remainder being an aluminum alloy containing aluminum and impurities.

[0060] (Manufacturing examples of supports B-2 to B-13) In the example of manufacturing support B-1, the support was prepared in the same manner as in the example of manufacturing support B-1, except that the same drawn tube was used and the annealing conditions were changed as shown in Table 1. The obtained supports were designated as supports B-2 to B-13.

[0061] (Manufacturing examples of support C-1 to C-11) In the example of manufacturing support A-1, a drawn tube with an outer diameter of 30.8 mm, an inner diameter of 28.5 mm, and a length of 370 mm was used, obtained by cold drawing an extruded tube made of JIS nominal 3003 alloy that had been hot extruded. The support was manufactured in the same manner as in the example of manufacturing support A-1, except that the annealing conditions were changed as shown in Table 1. The resulting supports were designated as supports C-1 to C-11.

[0062] (Manufacturing examples of support C-12 to support C-13) A drawn tube with an outer diameter of 30.8 mm, an inner diameter of 28.5 mm, and a length of 370 mm, made of an aluminum-magnesium (Al-Mg) alloy containing 2.5 mass% magnesium, was annealed under the conditions shown in Table 1. After annealing, the surface was mirror-cut to obtain supports C-12 and C-13, with an outer diameter of 30.5 mm, an inner diameter of 28.5 mm, and a length of 370 mm.

[0063] (Manufacturing examples of support D-1 to D-11) In the manufacturing example of support B-1, a drawn tube with an outer diameter of 30.8 mm, an inner diameter of 28.5 mm, and a length of 370 mm was used, obtained by cold drawing an extruded tube made of JIS nominal 6063 alloy that had been hot extruded. The support was manufactured in the same manner as in the manufacturing example of support A-1, except that the annealing conditions were changed as shown in Table 1. The obtained supports are designated as supports D-1 to D-11.

[0064] [Table 1]

[0065] <Manufacturing of electrophotographic photoconductors> (Manufacturing example of photoreceptor A-1) Support A-1 was used as the support, and the undercoat layer, charge generation layer, charge transport layer, and protective layer were formed as shown below.

[0066] <Formation of the underlayer> 100 parts of zinc oxide particles (specific surface area: 19 m² / g, powder resistance: 3.6 × 10⁶ Ω·cm) were mixed with 500 parts of toluene by stirring. 0.8 parts of N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane (trade name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) was added as a silane coupling agent, and the mixture was stirred for 6 hours. Subsequently, the toluene was removed by distillation under reduced pressure, and the mixture was heated and dried at 130°C for 6 hours to obtain surface-treated zinc oxide particles. Next, 15 parts of butyral resin (product name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) and 15 parts of blocked isocyanate (product name: Sumijule 3175, manufactured by Sumika Bayer Urethane Co., Ltd.) were dissolved in a mixed solution of 73.5 parts of methyl ethyl ketone and 73.5 parts of 1-butanol. To this solution, 80.8 parts of the surface-treated zinc oxide particles obtained above and 0.8 parts of 2,3,4-trihydroxybenzophenone (manufactured by Tokyo Chemical Industry Co., Ltd.) were added, and the mixture was dispersed for 3 hours in a sand mill apparatus using glass beads with a diameter of 0.8 mm at an atmosphere of 23±3°C. After dispersion, 0.01 parts of silicone oil (product name: SH28PA, manufactured by Toray Dow Corning Silicone Co., Ltd.) and 5.6 parts of cross-linked polymethyl methacrylate particles (product name: TECHPOLYMER SSX-102, manufactured by Sekisui Chemical Co., Ltd., average primary particle size 2.5 μm) were added and stirred to prepare a coating solution for the undercoat layer. This undercoat layer coating solution was applied to support A-1 by immersion, and the resulting coating film was dried at 160°C for 40 minutes to form an undercoat layer with a thickness of 18 μm.

[0067] <Formation of a charge generation layer> 20 parts of hydroxygallium phthalocyanine crystals (charge-generating material) in a crystalline form having peaks at 7.4° and 28.2° of the Bragg angle 2θ±0.2° in CuKα characteristic X-ray diffraction, and 0.2 parts of a calixarene compound represented by the following formula (A). [ka] Ten parts of polyvinyl butyral (product name: S-Rec BX-1, manufactured by Sekisui Chemical Co., Ltd.) and 600 parts of cyclohexanone were placed in a sand mill using 1 mm diameter glass beads and dispersed for 4 hours. Subsequently, 700 parts of ethyl acetate were added to prepare a coating solution for the charge generation layer. This coating solution for the charge generation layer was applied to the undercoat layer by immersion, and the resulting coating film was dried at 80°C for 15 minutes to form a charge generation layer with a thickness of 0.17 μm.

[0068] <Formation of charge transport layer> 30 parts of the compound represented by formula (B) below (charge transport material), 60 parts of the compound represented by formula (C) below (charge transport material), 10 parts of the compound represented by formula (D) below (charge transport material), [ka] 100 parts of polycarbonate resin (product name: Yupiron Z400, manufactured by Mitsubishi Engineering Plastics Corporation, bisphenol Z type polycarbonate), and 0.02 parts of polycarbonate represented by the following formula (E) (viscosity-average molecular weight Mv: 20000). [ka] A coating solution for the charge transport layer was prepared by dissolving it in a mixed solvent of 600 parts xylene and 200 parts dimethoxymethane. This coating solution for the charge transport layer was applied to the charge generating layer by immersion to form a coating film, and the resulting coating film was dried at 100°C for 30 minutes to form a charge transport layer with a thickness of 18 μm.

[0069] <Formation of a protective layer> A mixed solvent of 20 parts 1,1,2,2,3,3,4-heptafluorocyclopentane (trade name: Zeolora H, manufactured by Nippon Zeon Co., Ltd.) and 20 parts 1-propanol was filtered through a polyflon filter (trade name: PF-040, manufactured by Advantec Toyo Co., Ltd.). Then, 90 parts of a hole transport compound represented by the following formula (F) were added. [ka] 70 parts of 1,1,2,2,3,3,4-heptafluorocyclopentane and 70 parts of 1-propanol were added to the above mixed solvent. This was filtered again using a polyflon filter (product name: PF-020, manufactured by Advantec Toyo Co., Ltd.) to prepare a protective layer coating solution. This protective layer coating solution was applied to the charge transport layer by immersion, and the resulting coating film was dried in air at 50°C for 6 minutes. Subsequently, the coating film was irradiated with an electron beam for 1.6 seconds under the conditions of an accelerating voltage of 70kV and an absorbed dose of 8000Gy while rotating the support (irradiated object) at 200 rpm in nitrogen. Subsequently, the coating film was heated in nitrogen from 25°C to 125°C over 30 seconds. The oxygen concentration in the atmosphere during electron beam irradiation and subsequent heating was 15 ppm. Next, a protective layer with a thickness of 5 μm, cured by electron beam, was formed by heat treatment at 100°C for 30 minutes in air.

[0070] <Processing of the photoreceptor surface> The surface of the protective layer was polished using an abrasive sheet (product name: GC3000, manufactured by Riken Corundum Co., Ltd.). The feed speed of the abrasive sheet was set to 40 mm / min, the rotation speed of the workpiece to 240 rpm, and the pressure of the abrasive sheet against the protective layer to 7.5 N / m2. The feed direction of the abrasive sheet and the rotation direction of the photoreceptor were the same. A backup roller with an outer diameter of 40 cm and an Asker C hardness of 40 was used. Under these conditions, linear grooves were formed on the circumferential surface of the protective layer over 10 seconds to produce photoreceptor A-1.

[0071] (Manufacturing examples of photoreceptors A-2 to A-14) Except for using the support structures shown in Table 2, the electrophotographic photoreceptors were manufactured in the same manner as photoreceptor A-1. The obtained electrophotographic photoreceptors were designated "photoreceptors A-2 to A-14".

[0072] (Manufacturing examples of photoreceptors B-1 to B-13) Except for using the support structures shown in Table 2, the electrophotographic photoreceptors were manufactured in the same manner as photoreceptor A-1. The resulting electrophotographic photoreceptors were designated "photoreceptors B-1 to B-13".

[0073] (Manufacturing examples of photoreceptors C-1 to C-13) Except for using the support shown in Table 2, the electrophotographic photoreceptors were manufactured in the same manner as photoreceptor A-1. The obtained electrophotographic photoreceptors were designated "photoreceptors C-1 to C-13".

[0074] (Manufacturing examples of photoreceptors D-1 to D-11) Except for using the support structures shown in Table 2, electrophotographic photoreceptors were prepared in the same manner as photoreceptor A-1. The obtained electrophotographic photoreceptors were designated "photoreceptors D-1 to D-11".

[0075] [evaluation] (Example A-1) <Evaluation of surface directional uniformity> Photoreceptor A-1 was mounted in the cyan station of the evaluation device, an electrophotographic device (copier) (product name: imagePRESS C910, manufactured by Canon Inc.). First, 30,000 sheets of paper were passed through the paper under a 27°C / 60%RH environment, and then the surface potential was measured. The surface potential of photoreceptor A-1 was measured by removing the developing cartridge from the evaluation device, setting a potential probe (product name: model6000B-8, manufactured by Trek) in it, and using a surface potential meter (model344, manufactured by Trek). First, the dark area potential (Vd) of photoreceptor A-1 was adjusted to -600V at its axial center. Next, the bright area potential (Vl) of the surface of photoreceptor A-1 was evaluated under constant exposure light conditions of the exposure apparatus. Bright area potential measurements were taken at the axial center of photoreceptor A-1 and at 12 points every 30 degrees in the circumferential direction at 40 mm from both ends of photoreceptor A-1 (total: 3 points in the axial direction × 12 points in the circumferential direction = 36 points). Subsequently, the maximum and minimum surface potential values ​​at each of the 12 circumferential points of photoreceptor A-1 at each axial position were calculated. Of the obtained maximum and minimum surface potential values ​​at each axial position, the largest potential difference (V) was defined as the surface uniformity and evaluated according to the rank shown below. The evaluation results are shown in Table 2. Of the following ranks A to D, rank A is the best evaluation, and if the photoreceptor is rank C or higher, it will achieve the effects of the present invention. On the other hand, rank D is the same level of surface directional uniformity evaluation as conventional photoreceptors. Rank A: Surface directional unevenness is less than 10V Rank B: Surface directional unevenness is between 10V and 15V Rank C: Surface directional unevenness is between 15V and 20V Rank D: Surface directional unevenness is 20V or more

[0076] <Short-term potential fluctuation evaluation> A separate photoreceptor, A-1, was prepared in addition to the photoreceptor used for evaluating surface uniformity, and was mounted in the cyan station of the electrophotographic device (copier) (product name: imagePRESS C910, manufactured by Canon Inc.), which was used as the evaluation device. The surface potential of photoreceptor A-1 was measured by removing the developing cartridge from the evaluation device, setting a potential probe (product name: model6000B-8, manufactured by Trek) in it, and using a surface potential meter (model344, manufactured by Trek). First, the dark area potential (Vd) of photoreceptor A-1 was adjusted to -600V. Next, under constant exposure light conditions in the exposure apparatus, the bright area potential (Vl) of the surface of photoreceptor A-1 was evaluated. Bright area potential measurements were taken at the axial center of photoreceptor A-1 and at 12 points every 30 degrees in the circumferential direction at 40 mm from both ends of photoreceptor A-1 (total: 3 points in the axial direction × 12 points in the circumferential direction = 36 points). Subsequently, the average value of the circumferential bright area potential of photoreceptor A-1 at each axial position was calculated and used as the initial potential for each axial position. Next, the developing cartridge was returned to its original position, and 1,000 sheets were fed through under conditions of 27°C / 60%RH. Afterward, the potential probe was re-set, and the average value of the circumferential bright area potential of photoreceptor A-1 at each axial position was calculated as described above. This was then defined as the endurance potential at each axial position. Finally, the absolute difference between the initial potential and the endurance potential was calculated at each axial position, and the average value of these differences was calculated as the short-term potential fluctuation value. This was then evaluated using the ranks shown below. The evaluation results are shown in Table 3. In the following ranks A and B, rank A indicates that the photoreceptor achieves the effects of the present invention. On the other hand, rank B results in a short-term potential fluctuation value evaluation at the same level as conventional photoreceptors. Rank A: Short-term potential fluctuation less than 10V Rank B: Short-term potential fluctuation of 10V or more

[0077] <Area A (μm) at maximum frequency 2 ), half-width B (μm 2 ), and calculation of B / A > For photoreceptor A-1, which was used to evaluate short-term potential fluctuations, approximately 10 mm square sections were cut from four locations at 90-degree intervals in the circumferential direction (4 × 3 = 12 locations in total) 40 mm from both ends in the axial direction and at the center of the support in the axial direction. After removing the protective layer by polishing the sections with an abrasive sheet, the photosensitive layer was removed using methyl ethyl ketone. Subsequently, the support surface was exposed and mirror-finished by buff polishing. Next, a sample for measuring the area of ​​the crystal grains was obtained by immersion in an aqueous sodium hydroxide solution for 1 minute. A 100 μm square area of ​​the surface of the obtained sample was observed using the method described above, and the area of ​​the crystal grains was calculated. Subsequently, a crystal grain area distribution curve was created using the method described above, and the area A (μm²) at maximum frequency was calculated from the crystal grain area distribution curve. 2 ), the full width at half maximum B (μm) of the maximum peak in the area distribution curve. 2 The ratio () was calculated, and the B / A ratio was also calculated. The evaluation results are shown in Table 2.

[0078] (Examples A-2 to A-14 and Examples B-1 to B-13) Examples A-2 to A-14 and Examples B-1 to B-13 were conducted in the same manner as Example A-1, except that the photoreceptor A-1 used in Example A-1 was replaced with the photoreceptor shown in Table 2, and the planar unevenness and short-term potential fluctuations were evaluated, as well as the area A (μm²) at maximum frequency calculated from the area distribution curve of the crystal grains. 2 ), half-width B (μm 2 The following calculations were performed: ) and B / A.

[0079] (Comparative Examples C-1 to C-13 and D-1 to D-11) Except for replacing the photoreceptor A-1 used in Example A-1 with the photoreceptor shown in Table 2, the procedure was the same as in Example A-1, and in Comparative Examples C-1 to C-13 and D-1 to D-11, the planar unevenness was evaluated, and the area A (μm²) at maximum frequency was calculated from the area distribution curve of the crystal grains. 2 ), half-width B (μm 2 The following calculations were performed: ) and B / A. Furthermore, the area A (μm²) at the maximum frequency is calculated from the area distribution curve of the crystal grains. 2 ), half-width B (μm 2 The calculation of ), and B / A was performed using photoreceptors C-1 to C-13 and D-1 to D-11, which were prepared separately from the photoreceptor used for directional uniformity evaluation.

[0080] [Table 2]

[0081] [Table 3]

[0082] As can be seen from the description in Table 2, the photoreceptor of the present invention with a B / A ratio of 1.0 or less exhibits an effect of suppressing surface-direction unevenness in the output image. Furthermore, it can be seen that the photoreceptor with a B / A ratio of 0.7 or less, and even more so with a B / A ratio of 0.5 or less, exhibits an even stronger effect of suppressing surface-direction unevenness in the output image.

[0083] Furthermore, as can be seen from the information in Table 3, the average area of ​​the aluminum crystal grains is 10 μm². 2 This shows that it has the effect of reducing short-term potential fluctuations. This effect is due to the average area of ​​the aluminum crystal grains being 10 μm 2 This is thought to be because the ease of electron flow becomes less affected by grain boundaries, thereby suppressing the occurrence of initial charge stagnation on the support. [Explanation of Symbols]

[0084] 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. In an electrophotographic photoreceptor having a cylindrical support and a photosensitive layer formed on the support, The support is A support made of an aluminum alloy containing 0.6% by mass or less of silicon, 0.7% by mass or less of iron, 0.05% by mass or more and 0.2% by mass of copper, 1.0% by mass or more and 1.5% by mass of manganese, and 0.1% by mass or less of zinc, with the remainder being aluminum and impurities, or A support made of an aluminum alloy containing 0.2% to 0.6% by mass of silicon, 0.35% or less of iron, 0.1% or less of copper, 0.1% or less of manganese, 0.45% to 0.9% of magnesium, 0.1% or less of chromium, 0.1% or less of zinc, and 0.1% or less of titanium, with the remainder being aluminum and impurities. And, The area at maximum frequency, calculated from the area distribution curve of aluminum crystal grains on the surface of the support, is A (μm²). ２ Let B be the full width at half maximum of the maximum peak in the area distribution curve (μm). ２ When this is the case, the support satisfies the following formula (1): B / A≦1.0 Formula (1) An electrophotographic photoreceptor characterized by the following features.

2. The average area of ​​the aluminum crystal grains calculated from the aforementioned area distribution curve is 10 μm. ２ The electrophotographic photoreceptor according to claim 1, as described above.

3. The support satisfies the following formula (3): B / A≦0.5 Formula (3) The electrophotographic photoreceptor according to claim 1 or 2.

4. A process cartridge that integrally supports an electrophotographic photoreceptor according to any one of claims 1 to 3 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.

5. An electrophotographic photoreceptor according to any one of claims 1 to 3, and an electrophotographic apparatus having a charging means, an exposure means, a developing means, and a transfer means.

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