Image forming apparatus

Abstract

To provide an image forming apparatus that prevents variations in image density by preventing variations in bright part potential of photoconductor drums during repeated use for long period.SOLUTION: An image forming apparatus has a photoconductor drum, and a plurality of light emitting devices for emitting exposure light with which the surface of the photoconductor drum is irradiated. An undercoat layer of the photoconductor drum contains zinc oxide particles and a compound with a specific structure, and the light emitting device is an organic EL device.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an image forming apparatus. [Background technology]

[0002] In electrophotographic image forming devices such as laser beam printers and digital copiers, a solid-state exposure head is used as an exposure device for exposing a photosensitive drum. A solid-state exposure head has multiple light-emitting points, such as LEDs or organic EL elements, arranged in a substantially linear fashion in a direction parallel to the rotation axis of the photosensitive drum (the main scanning direction), and exposes the photosensitive drum all at once in the main scanning direction. This type of exposure device is smaller in volume and does not have a drive unit compared to laser scanning exposure devices that use a polygon mirror for scanning, making it advantageous for miniaturizing and reducing noise in the image forming device. Patent Document 1 discloses an image forming device that uses an LED as a solid-state exposure head.

[0003] Furthermore, photosensitive drums (drum-shaped electrophotographic photoreceptors) used in electrophotographic image forming devices are widely used that have an undercoat layer and a photosensitive layer on a support (conductive support). The undercoat layer plays roles such as concealing defects in the support and suppressing interference fringes, as well as preventing charge injection from the support and transporting electrons generated in the photosensitive layer.

[0004] The metal oxide particles used in the undercoat layer are surface-treated with a coupling agent to prevent black dot-like image defects (hereinafter also referred to as "black spots") caused by charge injection from the support to the photosensitive layer. Patent Document 2 discloses a technology in which metal oxide particles that have been surface-treated with a silane coupling agent having a substituted or unsubstituted amino group are contained in the undercoat layer. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2001-42554 [Patent Document 2] Japanese Patent Application Laid-Open No. 2004-191868 Summary of the Invention [Problem to be solved by the invention]

[0006] However, when organic EL elements are used as light-emitting elements in a solid-state exposure head and a photosensitive drum having an undercoat layer and a photosensitive layer on a support is used, potential fluctuations cannot be sufficiently suppressed during long-term repeated use, resulting in fluctuations in image density. In particular, there is a problem that the potential fluctuations and image density fluctuations are large during long-term repeated use. In other words, there is room for improvement in suppressing image density fluctuations during long-term repeated use of an image forming apparatus.

[0007] One aspect of the present disclosure is to provide an image forming apparatus in which fluctuations in image density are suppressed by suppressing fluctuations in the potential of light areas of a photosensitive drum during long-term repeated use. [Means for solving the problem]

[0008] According to one aspect of the present disclosure, there is provided an image forming apparatus having a photosensitive drum and a plurality of light-emitting elements for emitting exposure light to be irradiated onto the surface of the photosensitive drum, wherein an undercoat layer of the photosensitive drum contains zinc oxide particles and a compound represented by the following formula (BP), and the light-emitting elements are organic EL elements.

[0009] [ka]

[0010] (In formula (BP), R 1 ~R 10 each independently represents a hydrogen atom, a halogen atom, a hydroxy group, an alkyl group, an alkoxy group, or an amino group. 1 ~R 10 At least one of X is an amino group or a hydroxy group. 1 represents a carbonyl group or a dicarbonyl group. [Effects of the Invention]

[0011] According to one aspect of the present disclosure, it is possible to provide an image forming apparatus in which fluctuations in image density are suppressed by suppressing fluctuations in the potential of bright areas of a photosensitive drum during long-term repeated use. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 2 is a schematic diagram illustrating an example of a configuration of a photosensitive drum according to the present disclosure. [Figure 2] 1 is a diagram illustrating an example of a schematic configuration of an image forming apparatus according to the present disclosure. [Figure 3] FIG. 1 illustrates an example of a solid-state exposure head used in the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0013] The present disclosure will be described in detail below by way of preferred embodiments.

[0014] The image forming apparatus of the present disclosure includes a photosensitive drum and a plurality of light-emitting elements for emitting exposure light to irradiate the surface of the photosensitive drum, the light-emitting elements being organic EL elements. By incorporating zinc oxide particles and a compound represented by formula (BP) into the undercoat layer of the photosensitive drum, it is possible to obtain an image forming apparatus in which fluctuations in image density are suppressed by suppressing fluctuations in the light-area potential of the photosensitive drum during long-term repeated use.

[0015] The present inventors speculate as follows about the reason why the image forming apparatus of the present disclosure suppresses fluctuations in image density by suppressing fluctuations in the potential of the light areas of the photosensitive drum during long-term repeated use.

[0016] When organic EL elements are used as light-emitting elements, the light emission intensity gradually decreases with long-term repeated use of the image forming apparatus. As the light emission intensity decreases, the potential of the bright area on the photosensitive drum gradually increases from the initial level (hereinafter also referred to as "potential fluctuation").

[0017] On the other hand, when zinc oxide particles and the compound represented by formula (BP) are contained in the undercoat layer of a photosensitive drum, the dark potential gradually decreases with long-term repeated use. This is thought to be due to the fact that the undercoat layer containing zinc oxide particles is prone to dielectric relaxation. As the dark potential of the photosensitive drum decreases with long-term repeated use, the light potential also decreases accordingly.

[0018] By using an organic EL element as a light-emitting element in combination with a photosensitive drum containing zinc oxide particles in its undercoat layer, a rise in the bright area potential occurs due to a decrease in the luminous intensity of the organic EL element. Furthermore, a fall in the bright area potential occurs due to the photosensitive drum containing zinc oxide particles in its undercoat layer. It is presumed that by combining these bright area potential rises and bright area potential falls, the image forming apparatus as a whole can reduce the bright area potential fluctuations from the initial stage. In this way, the image forming apparatus of the present disclosure is believed to be able to suppress the bright area potential fluctuations of the photosensitive drum during long-term repeated use, and thus suppress image density fluctuations.

[0019] The configuration of the image forming apparatus of the present disclosure will be described below.

[0020] <Image forming device> The electrophotographic image forming apparatus of the present disclosure will be briefly described. The overall configuration of the apparatus is shown in Figure 2. This image forming apparatus is composed of a scanner unit 100, an image creating unit 103, a fixing unit 104, a paper feed / transport unit 105, and a printer control unit (not shown) that controls these units.

[0021] The scanner unit 100 illuminates a document placed on a platen, optically reads the document image, and converts the image into an electrical signal to create image data. The image-creating unit 103 rotates and drives the photosensitive drum 102, and charges the photosensitive drum 102 with a charger 107. The exposure head 106 (in the figure, 106a, b, c, and d indicate the arrangement of four exposure heads for full-color printing) emits light in accordance with the image data, and the light emitted from the chip surfaces of the arrayed light-emitting element group is focused onto the photosensitive drum 102 with a rod lens array to form an electrostatic latent image. The developer 108 develops the electrostatic latent image formed on the photosensitive drum 102 with toner. The developed toner image is transferred onto paper transported on a transfer belt 111.

[0022] The imaging unit has four imaging units that perform the electrophotographic process (charging, exposure, development, and transfer). These units are arranged in the order of cyan (C), magenta (M), yellow (Y), and black (K) to form a full-color image. After a predetermined time has passed since the start of image formation at the cyan station, the four imaging units sequentially perform image formation operations for magenta, yellow, and black. Paper feed / transport unit 105 feeds paper from a pre-selected paper feed unit among internal paper feed units 109a and 109b, external paper feed unit 109c, and manual paper feed unit 109d. The fed paper is transported to registration rollers 110. Registration rollers 110 transport the paper onto transfer belt 111 at the timing when the toner image formed by imaging unit 103 is transferred onto the paper. An optical sensor 113 is positioned opposite the transfer belt 111, and detects the position of a test chart printed on the transfer belt 111 to calculate the amount of color misregistration between each station. The calculated amount of color misregistration is notified to an image controller (not shown), which corrects the image position of each color. This control ensures that a full-color toner image is transferred onto the paper without color misregistration. The fixing unit 104 is made up of a combination of rollers and has a built-in heat source such as a halogen heater. It uses heat and pressure to melt and fix the toner on the paper onto which the toner image has been transferred from the transfer belt 111, and the paper is then discharged outside the image forming apparatus by paper discharge rollers 112.

[0023] The printer control unit (not shown) communicates with the MFP control unit (not shown) that controls the entire MFP, and executes control in accordance with its instructions, while managing the status of the aforementioned scanner, imaging, fixing, and paper feed / transport units, and issuing instructions to ensure that the entire unit operates smoothly and in harmony.

[0024] <Solid-state exposure head> FIG. 3 shows a cross-sectional view of a solid-state exposure head 201 as an example. A solid-state exposure head is also simply referred to as an exposure head. A light-emitting substrate 202, on which multiple light-emitting element chips are mounted and aligned in the main scanning direction (the direction of the rotation axis of the photosensitive drum), and a lens array 206, on which multiple cylindrical gradient index lenses are aligned in the same direction, are held in a housing 205. The light-emitting substrate 202 has multiple light-emitting elements for emitting exposure light to irradiate the surface of the photosensitive drum. The housing 205 is made of a galvanized steel plate or cold-rolled steel plate that has been plated afterward. The lens array 206 has a light-incident surface facing the light-emitting elements and a light-exiting surface facing the photosensitive drum. It is composed of multiple lenses aligned in the direction of the rotation axis for focusing the exposure light emitted from the light-emitting elements onto the surface of the photosensitive drum. The lens array 206 forms an erect image at 1:1 magnification on the photosensitive drum 102 using the light beams emitted from the light-emitting points 203. At this time, the distance from the light emitting point to the incident surface of the lens array 206 and the distance from the exit surface of the lens array 206 to the surface of the photosensitive drum 102 are approximately equal.

[0025] The distance between the light-emitting point 203 and the incident surface of the lens array 206 must be highly accurate on the order of μm, and after this distance is precisely adjusted, the light-emitting substrate 202 and the lens array 206 are fixed to the housing 205 by adhesive. In this embodiment, an organic EL element is used as the solid-state exposure light source, and the light-emitting substrate 202, lens array 206, and housing 205 integrated into one unit is called the solid-state exposure head 201.

[0026] In the solid-state exposure head of the image forming apparatus of the present disclosure, the light-emitting elements are organic EL elements.

[0027] Examples of light-emitting materials used in the organic EL device of the present disclosure, which are primarily involved in the light-emitting function, include fused ring compounds (e.g., fluorene derivatives, naphthalene derivatives, pyrene derivatives, perylene derivatives, tetracene derivatives, anthracene derivatives, rubrene, etc.), quinacridone derivatives, coumarin derivatives, stilbene derivatives, organoaluminum complexes such as tris(8-quinolinolato)aluminum, iridium complexes, platinum complexes, rhenium complexes, copper complexes, europium complexes, ruthenium complexes, and polymer derivatives such as poly(phenylenevinylene) derivatives, poly(fluorene) derivatives, and poly(phenylene) derivatives. Among these, perylene derivatives are preferred. Specific examples of compounds used as light-emitting materials are listed below, but the present invention is not limited to these.

[0028] [ka]

[0029] [ka]

[0030] Specific examples of the host or assist contained in the light-emitting layer include aromatic hydrocarbon compounds and their derivatives. Other examples include carbazole derivatives, azine derivatives, xanthone derivatives, dibenzofuran derivatives, dibenzothiophene derivatives, organoaluminum complexes such as tris(8-quinolinolato)aluminum, and organoberyllium complexes. However, these are not limiting. Specific examples are shown below.

[0031] [ka]

[0032] <Photosensitive drum> An example of the layer structure of a photosensitive drum according to the present disclosure is shown in Fig. 1. In Fig. 1, an undercoat layer 12, a charge generation layer 13, a charge transport layer 14, and a surface layer 15 are laminated on a support 11. The photosensitive layer may be a laminated photosensitive layer having a charge generation layer and a charge transport layer, or may be a single-layer photosensitive layer containing a charge generation material and a charge transport material.

[0033] A method for manufacturing the photosensitive drum of the present disclosure includes preparing a coating liquid for each layer described below, coating the desired layers in order, and drying the coating liquid. Examples of methods for applying the coating liquid include dip coating, spray coating, inkjet coating, roll coating, die coating, blade coating, curtain coating, wire bar coating, and ring coating. Among these, dip coating is preferred from the viewpoints of efficiency and productivity.

[0034] The configuration of the photosensitive drum of the present disclosure will be described below.

[0035] <Support> The support of the photosensitive drum is preferably conductive (conductive support). The support of the present disclosure has a drum (cylindrical) shape. The surface of the support may be subjected to electrochemical treatment such as anodization, blasting, cutting, or the like.

[0036] The support is preferably made of a metal, a resin, or a glass.

[0037] Examples of metals include aluminum, iron, nickel, copper, gold, stainless steel, and alloys thereof. Among these, an aluminum support using aluminum is preferred.

[0038] It is also preferable to impart electrical conductivity to the resin or glass by processing such as mixing or coating with an electrically conductive material.

[0039] <Undercoat layer> In the present disclosure, an undercoat layer is provided on the support or the conductive layer. The undercoat layer is provided for the purposes of improving the adhesion of the photosensitive layer, improving coating properties, improving charge injection from the support, protecting the photosensitive layer from electrical breakdown, and suppressing interference fringes due to scattering of image exposure. The undercoat layer may be a single undercoat layer containing one of the materials listed below, or two or more different undercoat layers containing the materials listed below may be laminated together.

[0040] At least one undercoat layer of the present disclosure contains zinc oxide particles. By installing a photosensitive drum having an undercoat layer containing zinc oxide particles in an image forming apparatus of the present disclosure that uses organic EL elements as light-emitting elements, it is possible to suppress fluctuations in image density during long-term repeated use.

[0041] The undercoat layer may further contain metal oxide particles or metal particles other than zinc oxide particles.

[0042] Examples of metal oxide particles other than zinc oxide particles include particles of indium tin oxide, tin oxide, indium oxide, titanium oxide, strontium titanate, and aluminum oxide. Silicon dioxide particles can also be used. Examples of metal particles include particles of gold, silver, and aluminum.

[0043] The primary particle size of metal oxide particles such as zinc oxide particles is preferably 0.1 μm or less in number average particle size from the viewpoint of dispersibility in the coating liquid for the undercoat layer and electrical properties of the photosensitive drum.

[0044] Two or more types of metal oxide particles such as zinc oxide particles may be used in combination, such as particles with different types of surface treatment, particle diameters, or specific surface areas.

[0045] In order to prevent black dot-like image defects caused by charge injection from the support to the photosensitive layer, the surfaces of metal oxide particles such as zinc oxide particles are preferably treated with a surface treatment agent such as a silane coupling agent.

[0046] Examples of silane coupling agents include N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, 3-aminopropylmethyldiethoxysilane, and (phenylaminomethyl)methyldimethoxysilane. Examples include N-2-(aminoethyl)-3-aminoisobutylmethyldimethoxysilane, N-ethylaminoisobutylmethyldiethoxysilane, and N-methylaminopropylmethyldimethoxysilane. Other examples include vinyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, methyltrimethoxysilane, and 3-glycidoxypropyltrimethoxysilane. Examples include 3-methacryloxypropyltrimethoxysilane, 3-chloropropyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane.

[0047] Among the various metal oxide particles described above, from the viewpoint of the electrical properties of the photosensitive drum, surface-treated zinc oxide particles are preferred, and zinc oxide particles surface-treated with N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane are most preferred.

[0048] The surface of metal oxide particles such as zinc oxide particles can be treated by a common method, such as a dry method or a wet method.

[0049] In the dry method, metal oxide particles such as zinc oxide particles are stirred in a mixer capable of high-speed stirring, such as a Henschel mixer, and an alcohol aqueous solution, organic solvent solution, or aqueous solution containing a surface treatment agent is added to the particles to uniformly disperse them, followed by drying.

[0050] In the wet method, metal oxide particles such as zinc oxide particles and a surface treatment agent are stirred in a solvent or dispersed in a sand mill using glass beads or the like, and the solvent is then removed by filtration or vacuum distillation. After the solvent is removed, the mixture is preferably baked at 100°C or higher.

[0051] The undercoat layer of the present disclosure also contains a compound represented by the following formula (BP): By containing an electron transport material represented by the following formula (BP), the electrical properties of the photosensitive drum can be improved.

[0052] [ka]

[0053] In formula (BP), R 1 ~R 10 each independently represents a hydrogen atom, a halogen atom, a hydroxy group, an alkyl group, an alkoxy group, or an amino group. 1 ~R 10 At least one of X is an amino group or a hydroxy group. 1 represents a carbonyl group or a dicarbonyl group.

[0054] Specific exemplary compounds represented by formula (BP) are shown below, but the present disclosure is not limited to these.

[0055] [ka]

[0056] [ka]

[0057] Furthermore, for the purpose of improving electrical properties, the undercoat layer may further contain, in addition to the compound represented by formula (BP), an electron transporting substance, metal particles, a conductive polymer, etc. Among these, it is preferable to use an electron transporting substance.

[0058] Examples of electron transport substances include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienylidene compounds, fluorenone compounds, oxadiazole compounds, diphenoquinone compounds, xanthone compounds, alizarin compounds, benzophenone compounds, cyanovinyl compounds, aryl halide compounds, silole compounds, and boron-containing compounds.

[0059] The undercoat layer preferably contains a resin. Alternatively, the undercoat layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group.

[0060] Examples of resins include acrylic resins, allyl resins, alkyd resins, ethyl cellulose resins, ethylene-acrylic acid copolymers, epoxy resins, casein resins, and silicone resins. Examples include gelatin resins, phenolic resins, urethane resins, butyral resins, polyacrylate resins, polyacetal resins, polyamide-imide resins, polyamide resins, polyallyl ethers, polyimide resins, polyester resins, and polyethylene resins. Other examples include polycarbonate resins, polystyrene resins, polysulfone resins, polyvinyl alcohol resins, polybutadiene resins, and polypropylene resins. Among these, urethane resins with low hygroscopicity are preferred from the viewpoint of suppressing potential fluctuations in high-temperature, high-humidity environments.

[0061] Examples of the polymerizable functional group include an isocyanate group, a blocked isocyanate group, a methylol group, an alkylated methylol group, an epoxy group, a metal alkoxide group, a hydroxy group, an amino group, a carboxy group, a thiol group, a carboxylic anhydride group, and a carbon-carbon double bond group.

[0062] The urethane resin preferably used for the undercoat layer is made of a polymer of a composition of an isocyanate compound or a blocked isocyanate compound and a polyol resin.

[0063] Examples of polyol resins include polyvinyl acetal resins and polyphenol resins.

[0064] Examples of blocked isocyanate compounds include 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and diphenylmethane-4,4'-diisocyanate blocked with a blocking agent. Examples of blocked isocyanate compounds include 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, IPDI) blocked with a blocking agent. Examples of blocked isocyanate compounds include hexamethylene diisocyanate (HDI), HDI-trimethylolpropane adduct, HDI-isocyanurate, and HDI-biuret blocked with a blocking agent.

[0065] Examples of blocking agents for blocked isocyanate compounds include oxime-based compounds such as formaldehyde oxime, acetaldoxime, methyl ethyl ketoxime, cyclohexanone oxime, acetone oxime, and methyl isobutyl ketoxime. Examples of active methylene-based compounds include Meldrum's acid, dimethyl malonate, diethyl malonate, di-n-butyl malonate, ethyl acetate, and acetylacetone. Examples of other blocking agents include amine-based compounds such as diisopropylamine, diphenylaniline, aniline, and carbazole, and imine-based compounds such as ethyleneimine and polyethyleneimine. Examples of other blocking agents include acid imide-based compounds such as succinimide and maleimide, and imidazole-based compounds such as malonate, imidazole, benzimidazole, and 2-methylimidazole. Examples of other blocking agents include triazole-based compounds such as 1,2,3-triazole, 1,2,4-triazole, 4-amino-1,2,4-triazole, and benzotriazole. Other examples include acid amide compounds such as acetanilide, N-methylacetamide, and acetic acid amide; lactam compounds such as ε-caprolactam, δ-valerolactam, and γ-butyrolactam; and urea compounds such as urea, thiourea, and ethyleneurea. Examples include sulfites such as sodium bisulfite; mercaptan compounds such as butyl mercaptan and dodecyl mercaptan; and phenolic compounds such as phenol and cresol. Other examples include pyrazole compounds such as pyrazole, 3,5-dimethylpyrazole, and 3-methylpyrazole; and alcohol compounds such as methanol, ethanol, 2-propanol, and n-butanol. Blocked isocyanate compounds may also be prepared by combining one or more of these blocking agents.

[0066] The mass ratio (P / B) of the metal oxide particles (P) to the binder resin (B) in the undercoat layer is preferably 1.0 / 1.0 or more and 3.0 / 1.0 or less.

[0067] The undercoat layer may be formed as a cured film by using an electron transporting substance having a polymerizable functional group as the electron transporting substance and copolymerizing it with the above-mentioned monomer having a polymerizable functional group.

[0068] The undercoat layer may further contain organic resin particles or a leveling agent for the purposes of, for example, adjusting surface roughness, promoting light scattering, or reducing cracking. The organic resin particles may be hydrophobic organic resin particles such as silicone particles or hydrophilic organic resin particles such as crosslinked polymethacrylate resin (PMMA) particles.

[0069] The undercoat layer may further contain additives, such as particles of conductive materials such as carbon black, charge transport materials, metal chelate compounds, organometallic compounds, and other known materials.

[0070] The undercoat layer can be formed by preparing a coating solution for the undercoat layer containing the above-mentioned materials and solvent, forming a coating film of this on the support or the conductive layer, and drying and / or curing it.

[0071] Examples of solvents used in the coating liquid for the undercoat layer include organic solvents such as alcohols, sulfoxides, ketones, ethers, esters, halogenated aliphatic hydrocarbons, aromatic compounds, etc. In the present disclosure, it is preferable to use alcohol-based and ketone-based solvents.

[0072] Dispersion methods for preparing the coating liquid for the undercoat layer include methods using a homogenizer, ultrasonic disperser, ball mill, sand mill, roll mill, vibration mill, attritor, and liquid collision type high-speed disperser.

[0073] The thickness of the undercoat layer is preferably 0.1 μm or more, more preferably 0.2 μm or more, and particularly preferably 0.3 μm or more, and is preferably 50 μm or less, more preferably 40 μm or less, and even more preferably 30 μm or less.

[0074] <Photosensitive layer> The photosensitive layer of a photosensitive drum is mainly classified into (1) a multi-layer type photosensitive layer and (2) a single-layer type photosensitive layer. (1) A multi-layer type photosensitive layer is a photosensitive layer having a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. (2) A single-layer type photosensitive layer is a photosensitive layer containing both a charge generation material and a charge transport material.

[0075] (1) Laminated photosensitive layer The laminated photosensitive layer has a charge generating layer and a charge transport layer.

[0076] (1-1) Charge generation layer The charge generating layer preferably contains a charge generating material and a resin.

[0077] 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.

[0078] The content of the charge generating material in the charge generating layer is preferably 40% by mass or more and 85% by mass or less, and more preferably 60% by mass or more and 80% by mass or less, based on the total mass of the charge generating layer.

[0079] Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, polyvinyl butyral resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinyl alcohol resin, cellulose resin, polystyrene resin, polyvinyl acetate resin, polyvinyl chloride resin, etc. Among these, polyvinyl butyral resin is more preferred.

[0080] The charge generating layer may further contain additives such as antioxidants and ultraviolet absorbers, etc. Specific examples include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, and benzophenone compounds.

[0081] The charge generating layer can be formed by preparing a coating solution for the charge generating layer containing the above-mentioned materials and solvent, forming a coating film of this on the undercoat layer, and drying it. Examples of the solvent used in the coating solution include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0082] The thickness of the charge generating layer is preferably 0.1 μm or more and 1 μm or less, and more preferably 0.15 μm or more and 0.4 μm or less.

[0083] (1-2) Charge transport layer The charge transport layer preferably contains a charge transport material and a binder material.

[0084] Examples of the charge transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, triarylamine compounds, and resins having groups derived from these materials. Among these, triarylamine compounds are preferred.

[0085] The content of the charge transport material in the charge transport layer is preferably 25% by mass to 70% by mass, and more preferably 30% by mass to 55% by mass, based on the total mass of the charge transport layer.

[0086] As the binding material, a thermoplastic resin (hereinafter also referred to as "resin") is used.

[0087] Examples of thermoplastic resins include polyester resins, polycarbonate resins, acrylic resins, and polystyrene resins. Among these, polycarbonate resins and polyester resins are preferred. As the polyester resin, polyarylate resins are particularly preferred.

[0088] 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.

[0089] The charge transport layer may also contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, etc. Specific examples of such additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, polystyrene resin particles, polyethylene resin particles, and boron nitride particles.

[0090] The charge transport layer can be formed by preparing a coating solution for the charge transport layer containing the above-mentioned materials and solvent, forming a coating film of this on the charge generation layer, and drying it. Examples of solvents used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, ether-based solvents and aromatic hydrocarbon-based solvents are preferred.

[0091] The thickness of the charge transport layer is preferably from 5 μm to 50 μm, more preferably from 8 μm to 40 μm, and particularly preferably from 10 μm to 30 μm.

[0092] (2) Single-layer photosensitive layer The single-layer photosensitive layer can be formed by preparing a coating solution for the photosensitive layer containing a charge generating material, a charge transport material, a resin, and a solvent, forming the coating on the undercoat layer, and drying the coating. The charge generating material, charge transport material, and resin are the same as those exemplified in "(1) Multilayer Photosensitive Layer" above.

[0093] <Protective layer> In the present disclosure, a protective layer is provided on the photosensitive layer, which can improve durability.

[0094] The protective layer may be formed as a cured film by polymerizing a composition containing, for example, a monomer having a polymerizable functional group, which is a raw material for the binder material. Examples of the reaction include thermal polymerization, photopolymerization, and radiation polymerization. Examples of the polymerizable functional group possessed by the monomer having the polymerizable functional group include an isocyanate group, a blocked isocyanate group, a methylol group, an alkylmethylol group, an epoxy group, a metal alkoxyl group, a hydroxyl group, an amino group, a carboxyl group, a thiol group, a carboxylic anhydride group, and a group containing a carbon-carbon double bond. Examples of the group containing a carbon-carbon double bond include an acryloyl group and a methacryloyl group. A monomer having charge transport capability may be used as the monomer having the polymerizable functional group.

[0095] Here, the cured product of the monomer having a polymerizable functional group is the binder material of the protective layer.

[0096] The polymerizable functional group is preferably a chain-polymerizable functional group. As the monomer having a polymerizable functional group, it is preferable to use a hole transporting compound having a chain-polymerizable functional group.

[0097] The hole transporting compound having a chain-polymerizable functional group is more preferably a compound represented by the following formula (CT-1) or (CT-2).

[0098] [ka]

[0099] In the formula (CT-1), Ar 11 ~Ar 13 are each independently a substituted aryl group or an unsubstituted aryl group. The substituent that the substituted aryl group may have is an alkyl group having from 1 to 6 carbon atoms, or a monovalent functional group represented by any one of the following formulae (P-1) to (P-3). However, the compound represented by formula (CT-1) has at least one monovalent functional group represented by any one of the following formulae (P-1) to (P-3).

[0100] [ka]

[0101] In the formula (CT-2), Ar 21 ~Ar 24 each independently represents a substituted aryl group or an unsubstituted aryl group, Ar 25 represents a substituted arylene group or an unsubstituted arylene group. The substituent that the substituted aryl group may have is an alkyl group having 1 to 6 carbon atoms, or a monovalent functional group represented by any of the following formulae (P-1) to (P-3). The substituent that the substituted arylene group may have is an alkyl group having 1 to 6 carbon atoms, or a monovalent functional group represented by any of the following formulae (P-1) to (P-3). However, the compound represented by formula (CT-2) has at least one monovalent functional group represented by any of the following formulae (P-1) to (P-3).

[0102] [ka]

[0103] In the formula (P-1), Z 11 represents a single bond or an alkylene group having 1 to 6 carbon atoms, and X 11 represents a hydrogen atom or a methyl group.

[0104] [ka]

[0105] In the formula (P-2), Z 21 represents a single bond or an alkylene group having 1 to 6 carbon atoms.

[0106] [ka]

[0107] In the formula (P-3), Z31 represents a single bond or an alkylene group having 1 to 6 carbon atoms.

[0108] The protective layer may contain organic resin particles, which can improve the abrasion resistance of the protective layer.

[0109] Examples of organic resin particles include fluorine atom-containing resin particles, silicone resin particles, polystyrene resin particles, and polyethylene resin particles.

[0110] Among these, fluorine atom-containing resin particles are preferred from the viewpoint of dispersibility.

[0111] Examples of resins contained in the fluorine atom-containing resin particles include polytetrafluoroethylene resin, polychlorotrifluoroethylene resin, polytetrafluoroethylenepropylene resin, polyvinyl fluoride resin, polyvinylidene fluoride resin, and polydichlorodifluoroethylene resin. It is also preferable to use particles containing multiple types of the above resins. Among the above, from the viewpoint of improving dispersibility, it is more preferable that the fluorine atom-containing resin particles be polytetrafluoroethylene (PTFE) resin.

[0112] In cross-sectional observation of the surface layer, the fluorine atom-containing resin particles preferably have an arithmetic mean of the major axes of the primary particles (average primary particle size) measured from a secondary electron image taken with a scanning electron microscope of 150 nm to 300 nm, from the viewpoints of improving dispersibility and suppressing potential fluctuations.More preferably, the fluorine atom-containing resin particles have an average primary particle size of 180 nm to 250 nm.

[0113] The content of the fluorine atom-containing resin particles in the protective layer is preferably from 5 to 40% by mass, more preferably from 25 to 35% by mass, based on the total mass of the protective layer.

[0114] The protective layer may also contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, etc. Specific examples of such additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, polystyrene resin particles, polyethylene resin particles, and boron nitride particles.

[0115] The protective layer can be formed by preparing a coating solution for the protective layer containing the above-mentioned materials and solvent, forming a coating film of this on the photosensitive layer, and drying and / or curing it. Examples of the solvent 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.

[0116] The thickness of the protective layer is preferably 0.50 μm or more and 10 μm or less, and more preferably 1 μm or more and 7 μm or less.

[0117] As described above, the protective layer may have charge transport capability. When the photosensitive layer is a laminated photosensitive layer having a charge generation layer and a charge transport layer, the protective layer having charge transport capability may also be called a second charge transport layer.

[0118] <Surface treatment of photosensitive drum> In the present disclosure, the surface of the photosensitive drum may be processed. By performing the surface processing, the behavior of the cleaning means (cleaning blade) that comes into contact with the photosensitive drum can be more stabilized. Examples of surface processing methods include a method in which a mold having convex portions is pressed against the surface of the photosensitive drum to transfer the shape, and a method in which an uneven shape (for example, multiple grooves formed in the approximately circumferential direction of the peripheral surface of the photosensitive drum) is imparted by mechanical polishing. Another example is a method in which powder is collided with the surface of the photosensitive drum to roughen the surface. In this way, by providing concave or convex portions on the surface layer of the photosensitive drum, the behavior of the cleaning means that comes into contact with the photosensitive drum can be more stabilized.

[0119] The above concave or convex portion may be formed over the entire surface of the photosensitive drum, or may be formed on a part of the surface of the photosensitive drum. When the concave or convex portion is formed on a part of the surface of the photosensitive drum, it is preferable that the concave or convex portion is formed over the entire contact area with at least the cleaning means (cleaning blade).

[0120] When forming a concave portion, a concave portion can be formed on the surface of the photosensitive drum by pressing a mold having a convex portion corresponding to the concave portion against the surface of the photosensitive drum and performing shape transfer.

[0121] <Measurement of maximum height Rmax in JIS B0601 1982> The surface roughness of the photosensitive drum can be measured by known means. For example, the following can be mentioned. Surface roughness meters such as the Surf Coader SE3500 type surface roughness measuring instrument manufactured by Kosaka Laboratory Ltd. Non-contact three-dimensional surface measuring machine Micromap 557N manufactured by Hishikawa System Co., Ltd. Microscopes capable of acquiring three-dimensional shapes such as the ultra-depth shape measuring microscope VK-8550 and VK-9000 manufactured by Keyence Corporation.

[0122] In the present disclosure, among the indexes of surface roughness, the maximum height Rmax in JIS B0601 1982 defined by the Japanese Industrial Standard JIS is used as the polishing depth L (μm). Further, in the present disclosure, the Rmax is measured in advance for the range of the 5 mm square section of the photosensitive drum cut out as a specimen for X-ray photoelectron spectroscopy described later. The measurement is performed arbitrarily at three locations in the range of the 5 mm square of the cut-out photosensitive drum, and the average value is adopted as the polishing depth L (μm).

Examples

[0123] Hereinafter, the technology of the present disclosure will be described in more detail using examples and comparative examples, but it is not limited thereto. In the description of the following examples, "parts" means on a mass basis unless otherwise specified.[[ID=……]] [[ID=……]]

[0124] [[ID=……]] [[ID=……]]<0感光ドラムの作製>[[ID=……]] [Photosensitive drum 1] (Support 1) A cylindrical aluminum cylinder (JIS-A3003, aluminum alloy, outer diameter 30 mm, length 357.5 mm, wall thickness 0.7 mm) was used as the support (conductive support). It was ultrasonically cleaned in a cleaning solution containing pure water and detergent (product name: Chemicol CT, manufactured by Tokiwa Chemical Co., Ltd.), and after the cleaning solution was rinsed off, it was further ultrasonically cleaned in pure water and degreased. This was designated Support 1.

[0125] (Undercoat layer 1) Zinc oxide particles (average primary particle size 50 nm, specific surface area: 19 m 2 / g, powder resistance: 4.7×10 6 100 parts of the sol-gel (Ω·cm) was mixed with 500 parts of toluene and stirred, to which 0.8 parts of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, product name: KBM602, manufactured by Shin-Etsu Chemical Co., Ltd.) was added and stirred for 6 hours. Thereafter, the toluene was distilled off under reduced pressure, and the particles were dried by heating at 130°C for 6 hours to obtain surface-treated zinc oxide particles A.

[0126] Next, 15 parts of butyral (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) as a polyol and 15 parts of blocked isocyanate (trade name: Duranate TPA-B80E, nonvolatile content 80% by mass, manufactured by Asahi Kasei Chemicals Corp.) were dissolved in a mixed solvent of 73.5 parts of methyl ethyl ketone and 73.5 parts of 1-butanol. To this solution, 80.8 parts of surface-treated zinc oxide particles A and 0.81 parts of 2,3,4-trihydroxybenzophenone (manufactured by Tokyo Chemical Industry Co., Ltd.) were added, and the mixture was dispersed in a sand mill using glass beads with a diameter of 0.8 mm in an atmosphere of 23±3°C for 3 hours.

[0127] After the dispersion process, 0.01 parts of silicone oil (trade name: SH28PA, manufactured by Toray Dow Corning Co., Ltd. (formerly Toray Dow Corning Silicones Co., Ltd.)) and 5.6 parts of cross-linked polymethyl methacrylate (PMMA) particles (trade name: Techpolymer SSX-103, manufactured by Sekisui Plastics Co., Ltd., average primary particle size: 3 μm) were added and stirred to prepare a coating solution for the undercoat layer.

[0128] The obtained coating liquid for undercoat layer was dip-coated onto the support 1 to form a coating film, and the coating film was dried at 160° C. for 30 minutes to form an undercoat layer 1 with a film thickness of 18 μm.

[0129] (Charge generation layer 1) Four parts of hydroxygallium phthalocyanine crystals (charge generating material) in a crystalline form having strong peaks at Bragg angles 2θ±0.2° (7.4° and 28.1°) in CuKα characteristic X-ray diffraction and 0.04 parts of a compound represented by the following formula (K) were added to a solution prepared by dissolving 2 parts of polyvinyl butyral (trade name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.) in 100 parts of cyclohexanone. The mixture was then dispersed for 1 hour in a sand mill using 1 mm diameter glass beads in an atmosphere of 23±3°C, and after the dispersion process, 100 parts of ethyl acetate was added to prepare a coating solution for a charge generating layer.

[0130] This charge generating layer coating liquid was dip coated onto the undercoat layer 1, and the resulting coating was dried at 90° C. for 10 minutes to form a charge generating layer 1 having a thickness of 0.15 μm.

[0131] [ka]

[0132] (Charge transport layer 1) A coating solution for a charge transport layer was prepared by dissolving 60 parts of a compound represented by the following formula (L), 30 parts of a compound represented by the following formula (M), 10 parts of a compound represented by the following formula (N), 100 parts of a bisphenol Z-type polycarbonate resin (trade name: Iupilon Z400, manufactured by Mitsubishi Engineering-Plastics Corporation), and 0.2 parts of a polycarbonate having a structural unit represented by the following formula (O) (viscosity average molecular weight Mv: 20,000) in a mixed solvent of 272 parts of o-xylene, 256 parts of methyl benzoate, and 272 parts of dimethoxymethane.

[0133] This charge transport layer coating liquid was dip coated onto the charge generating layer 1 to form a coating film, and the resulting coating film was dried at 115° C. for 50 minutes to form a charge transport layer 1 having a thickness of 18 μm.

[0134] [ka]

[0135] [ka]

[0136] [ka]

[0137] [ka]

[0138] (In formula (I), 0.95 and 0.05 are the molar ratios (copolymerization ratios) of the two structural units.)

[0139] (Protective layer 1) A dispersant solution was prepared by dissolving 2.20 parts of a resin (weight average molecular weight: 130,000) having a structural unit represented by the following structural formula (A) in a mixed solvent consisting of 100 parts of 1,1,2,2,3,3,4-heptafluorocyclopentane (trade name: Zeorora H, manufactured by Nippon Zeon Co., Ltd.) and 100 parts of 1-propanol.

[0140] To the obtained dispersant solution, 40 parts of polytetrafluoroethylene resin microparticles (trade name: Lubron L-2, average primary particle size 200 nm, manufactured by Daikin Industries, Ltd.) were added, and the mixture was passed through a high-pressure disperser (trade name: Microfluidizer M-110EH, manufactured by Microfluidics, Inc., USA) to obtain a polytetrafluoroethylene resin microparticle dispersion.

[0141] [ka]

[0142] (In formula (A), 0.5 is the molar ratio (copolymerization ratio) of the two structural units.)

[0143] To the obtained polytetrafluoroethylene resin microparticle dispersion, 75.4 parts of a hole transport compound represented by the following structural formula (B) and 100 parts of 1-propanol were added and mixed, and the mixture was filtered through a Polyflon filter (trade name: PF-040, manufactured by Advantech Toyo Co., Ltd.) to prepare a polytetrafluoroethylene resin microparticle dispersion (coating liquid for surface layer).

[0144] [ka]

[0145] This protective layer coating solution was dip-coated onto the charge transport layer 1 to form a coating film, and the resulting coating film was dried at 40°C for 5 minutes. After drying, the coating film was irradiated with an electron beam for 1.6 seconds under a nitrogen atmosphere at an acceleration voltage of 70 kV and an absorbed dose of 15 kGy. Then, a heat treatment was performed for 15 seconds under a nitrogen atmosphere to bring the coating film temperature to 135°C. The oxygen concentration from the electron beam irradiation to the 15-second heat treatment was 15 ppm. Next, the coating film was naturally cooled in the atmosphere to 25°C, and then heat-treated for 1 hour under conditions to bring the coating film temperature to 105°C, forming a protective layer 1 with a thickness of 5 μm.

[0146] In this way, a photosensitive drum having a support and a surface layer before surface polishing was prepared.

[0147] <Surface treatment of photosensitive drum> (Photosensitive drum polishing before surface polishing) The surface of the photosensitive drum before the surface shape formation was polished under the following conditions. Abrasive sheet feed speed: 400mm / min Photosensitive drum rotation speed: 450 rpm Pressing of the photosensitive drum onto the backup roller: 3.5 mm Rotation direction of the abrasive sheet and photosensitive drum; Backup roller; outer diameter 100 mm, Asker C hardness 25

[0148] The polishing sheet A to be attached to the polishing device was made by mixing the polishing grains used in GC3000 and GC2000 manufactured by Riken Corundum Co., Ltd. GC3000 (abrasive sheet surface roughness Ra0.83μm) GC2000 (abrasive sheet surface roughness Ra1.45μm) Polishing sheet A (polishing sheet surface roughness Ra1.12μm)

[0149] The polishing time using the polishing sheet A was 20 seconds.

[0150] By the above-described polishing, a plurality of grooves were formed in the approximately circumferential direction on the peripheral surface of the photosensitive drum. The same applies to photosensitive drums 2 to 7, which will be described later.

[0151] (Measurement of polishing depth L (μm)) The maximum height Rmax of the polished photosensitive drum was measured in accordance with JIS B 0601 1982 using a surface roughness measuring instrument, Surfcorder SE3500, manufactured by Kosaka Laboratory Co., Ltd. The measurement conditions were set as follows. Measurements were performed at three random locations within a 5 mm square area of ​​the polished photosensitive drum, and the average value was used as the polishing depth L (μm). The polishing depth L of the photosensitive drum after surface polishing was 0.75 μm. Furthermore, for photosensitive drums 2 to 7 described below, the polishing depth L of the surface-treated photosensitive drums was all 0.75 μm.

[0152] (Measurement conditions) Detector: R2μm Stylus: 0.7mN diamond stylus Filter: 2CR Cutoff value: 0.08 mm Measurement length: 2.5 mm Feed speed: 0.1 mm

[0153] In this way, a photosensitive drum 1 with a polished surface was produced.

[0154] [Photosensitive drum 2] Photosensitive drum 2 was produced in the same manner as photosensitive drum 1, except that in the formation of the protective layer, protective layer 2 was formed as follows.

[0155] (Protective layer 2) 3.31 parts of 1H,1H,2H,2H-perfluorohexyl methacrylate (Fujifilm Wako Pure Chemical Industries, Ltd.), 180 parts of a macromonomer (number average molecular weight 6,000) represented by the following formula (A-1), 8.51 parts of 1,1'-azobis(1-acetoxy-1-phenylethane) (trade name: OTAZO-15, Otsuka Chemical Co., Ltd.), and 900 parts of n-butyl acetate were mixed in a glass flask equipped with a stirrer, reflux condenser, nitrogen gas inlet tube, thermostatic bath, and thermometer at 20°C under a nitrogen atmosphere for 30 minutes, and then the reaction mixture was heated to 85-90°C and reacted for 5 hours. The reaction was stopped by cooling with ice, and 4500 parts of 2-propanol was added to obtain a precipitate. The precipitate was washed with a mixed solvent of n-butyl acetate:2-propanol=1:5 and dried at a temperature of 50° C. under reduced pressure of 1325 Pa or less for 2 hours to obtain graft copolymer X.

[0156] [ka]

[0157] The resulting graft copolymer X was subjected to GPC measurement by the following method, and the weight average molecular weight (Mw) was calculated to be Mw 250,000.

[0158] (Weight average molecular weight measured by GPC) The weight average molecular weight according to the present disclosure is measured by gel permeation chromatography (GPC) as follows.

[0159] First, the sample is dissolved in tetrahydrofuran (THF) at room temperature for 24 hours. The resulting solution is then filtered through a solvent-resistant membrane filter "Maesholidisc" (Tosoh Corporation) with a pore size of 0.2 μm to obtain a sample solution. The sample solution is prepared so that the concentration of components soluble in THF is approximately 0.8 mass%. This sample solution is used for measurements under the following conditions. Apparatus: HLC8120 GPC (detector: RI) (Tosoh Corporation) Column: Shodex KF-801, 802, 803, 804, 805, 806, 807 (7 columns, manufactured by Showa Denko Co., Ltd.) Eluent: tetrahydrofuran (THF) ·Flow rate: 1.0ml / min Oven temperature: 40.0℃ Sample injection volume: 0.10 ml

[0160] To calculate the molecular weight of a sample, a molecular weight calibration curve prepared using standard polystyrene resins (e.g., trade names "TSK Standard Polystyrene F-850, F-450, F-288, F-128, F-80, F-40, F-20, F-10, F-4, F-2, F-1, A-5000, A-2500, A-1000, A-500", manufactured by Tosoh Corporation) is used.

[0161] A dispersant solution was prepared by dissolving 2.8 parts of the graft copolymer X in a mixed solvent consisting of 100 parts of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (product name: AE-3000, manufactured by AGC Corporation) and 100 parts of 1-propanol.

[0162] To the resulting dispersant solution, 40 parts of polytetrafluoroethylene resin particles (average primary particle size 210 nm, average circularity 0.85) were added, and the mixture was passed through a high-pressure disperser (product name: Microfluidizer M-110EH, manufactured by Microfluidics, Inc., USA) to obtain a polytetrafluoroethylene resin particle dispersion.

[0163] To the obtained polytetrafluoroethylene resin particle dispersion, 75.4 parts of the hole transport compound represented by the above formula (B), 21.9 parts of the compound represented by the following formula (C), and 100 parts of 1-propanol were added, and then the mixture was filtered with a Polyflon filter (trade name: PF-040, manufactured by Advantec Toyo Co., Ltd.) to prepare a polytetrafluoroethylene resin particle dispersion (coating liquid for protective layer).

[0164] [ka]

[0165] This protective layer coating solution was dip-coated onto the charge transport layer 1 to form a coating film, and the resulting coating film was dried at 40°C for 5 minutes. After drying, the coating film was irradiated with an electron beam for 1.6 seconds under a nitrogen atmosphere at an acceleration voltage of 70 kV and an absorbed dose of 15 kGy. Then, a heat treatment was performed for 15 seconds under a nitrogen atmosphere to bring the coating film temperature to 135°C. The oxygen concentration from the electron beam irradiation to the 15-second heat treatment was 15 ppm. Next, the coating film was naturally cooled in the atmosphere to a temperature of 25°C, and then heat-treated for 1 hour under conditions to bring the coating film temperature to 105°C, forming a protective layer 2 with a thickness of 5 μm.

[0166] [Photosensitive drum 3] A photosensitive drum 3 was produced in the same manner as the photosensitive drum 1, except that in the formation of the protective layer, a protective layer 3 was formed as follows.

[0167] (Protective layer 3) 16.25 parts of the compound represented by formula (B), 8.75 parts of a hole-transporting compound represented by formula (D) below, and 0.1 parts of a siloxane-modified acrylic compound (trade name: US270, manufactured by Toagosei Co., Ltd.) were dissolved in a mixed solvent consisting of 12 parts of 1-propanol and 27 parts of cyclohexane, and the mixture was stirred. The mixture was then filtered through a Polyflon filter (trade name: FP-022, manufactured by Sumitomo Electric Fine Polymer Co., Ltd.) to prepare a coating solution for a protective layer.

[0168] This protective layer coating solution was dip-coated onto the charge transport layer 1 to form a coating film, which was then dried at 40°C for 5 minutes. After drying, the coating film was irradiated with an electron beam for 1.6 seconds under a nitrogen atmosphere at an acceleration voltage of 70 kV and an absorbed dose of 15 kGy. The coating film was then heat-treated for 15 seconds under a nitrogen atmosphere to a temperature of 135°C. The oxygen concentration from the electron beam irradiation to the 15-second heat treatment was 15 ppm. The coating film was then naturally cooled in the atmosphere to a temperature of 25°C, and then heat-treated for 1 hour to a temperature of 105°C, forming a protective layer 3 with a thickness of 5 μm.

[0169] [ka]

[0170] [Photosensitive drum 4] Photosensitive drum 4 was produced in the same manner as photosensitive drum 1, except that the formation of the undercoat layer was changed to undercoat layer 2 formed as follows, and the formation of the protective layer was changed to protective layer 4 formed as follows.

[0171] (Undercoat layer 2) Zinc oxide particles (average particle size: 70 nm, specific surface area: 15 m 2 Sixty parts of zinc oxide particles (60 parts by weight / g) were mixed with 500 parts of tetrahydrofuran by stirring, and 0.75 parts of a silane coupling agent (compound name: N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, product name: KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.) was added thereto and stirred for 2 hours. Thereafter, the tetrahydrofuran was distilled off under reduced pressure, and the mixture was dried by heating at 120°C for 3 hours to obtain surface-treated zinc oxide particles.

[0172] Next, 25 parts of butyral (trade name: BM-1, manufactured by Sekisui Chemical Co., Ltd.) as a polyol and 22.5 parts of blocked isocyanate (trade name: Sumidur BL-3173, manufactured by Sumitomo Bayer Urethane Co., Ltd.) were dissolved in 142 parts of methyl ethyl ketone. To this solution, 100 parts of the surface-treated zinc oxide particles and 1 part of alizarin were added, and the mixture was dispersed for 5 hours in a sand mill using glass beads with a diameter of 1 mm.

[0173] After the dispersion treatment, 0.008 parts of dioctyltin dilaurate and 6.5 parts of silicone resin particles (product name: Tospearl 145, manufactured by GE Toshiba Silicones) were added and stirred to prepare a coating liquid for an undercoat layer.

[0174] The obtained coating liquid for undercoat layer was dip-coated onto the support 1 to form a coating film, and the coating film was dried at 190° C. for 24 minutes to form an undercoat layer 2 with a thickness of 15 μm.

[0175] (Protective layer 4) 115 parts of a charge transporting compound represented by the following formula (E), 8 parts of a triazine compound represented by the following formula (F), 2.2 parts of 3,5-di-t-butyl-4-hydroxytoluene (BHT), and 0.3 parts of dodecylbenzenesulfonic acid were dissolved in a mixed solvent consisting of 120 parts of cyclopentanone and 120 parts of cyclopentanol. The solution was then filtered through a Polyflon filter (trade name: PF-020, manufactured by Advantec Toyo Co., Ltd.) to prepare a coating solution for a protective layer.

[0176] This protective layer coating liquid was dip-coated onto the charge transport layer 1 to form a coating film, and the resulting coating film was subjected to a curing (crosslinking) reaction at 150°C for 60 minutes in a thermal dryer to form a protective layer 4 with a thickness of 6 μm.

[0177] [ka]

[0178] [ka]

[0179] [Photosensitive drum 5] Photosensitive drum 5 was produced in the same manner as photosensitive drum 1, except that in the formation of the protective layer, a protective layer 5 was formed as follows.

[0180] (Protective layer 5) A coating solution for a protective layer was prepared by mixing 14.5 parts of a hole transporting compound represented by the following formula (G), 5.5 parts of a compound represented by the following formula (H), 0.20 parts of a compound represented by the following formula (I), 0.5 parts of a photopolymerization initiator 1-hydroxycyclohexyl phenyl ketone, and 80 parts of tetrahydrofuran.

[0181] [ka]

[0182] [ka]

[0183] [ka]

[0184] This protective layer coating solution was dip-coated onto the charge transport layer 1 to form a coating film, and the resulting coating film was dried for 5 minutes at 60° C. After drying, the coating film was irradiated with light at an irradiation intensity of 700 mW / cm using a metal halide lamp with an output of 160 W / cm. 2 The coated film was irradiated with ultraviolet light at 130° C. for 120 seconds, and then heat-treated at 130° C. for 30 minutes to form a protective layer 5 having a thickness of 5.0 μm.

[0185] [Photosensitive drum 6] Photosensitive drum 6 was produced in the same manner as photosensitive drum 5, except that in the formation of the undercoat layer, undercoat layer 3 and undercoat layer 4 were formed as follows.

[0186] (Undercoat layer 3) Five parts of N-methoxymethylated nylon (FR101, manufactured by Lead City Co., Ltd.), 70 parts of methanol, and 30 parts of n-butanol were mixed together to prepare a coating liquid for an undercoat layer.

[0187] This coating solution for undercoat layer 1 was dip-coated onto the support 1 to form a coating film, and the resulting coating film was dried by heating at 130° C. for 10 minutes to form an undercoat layer 3 with a thickness of 0.7 μm.

[0188] (Undercoat layer 4) 24 parts of alkyd resin (Beckolite M6401-50, manufactured by DIC Corporation), 16 parts of melamine resin (Amidia L-150-60, manufactured by DIC Corporation), 160 parts of titanium oxide particles (CR-EL, average primary particle size 0.25 μm, manufactured by Ishihara Sangyo Kaisha, Ltd.), and 500 parts of methyl ethyl ketone were mixed. The mixture was then dispersed for 10 hours using a sand mill equipped with 0.8 mm diameter glass beads to prepare a coating solution for an undercoat layer. This coating solution for an undercoat layer was dip-coated onto the undercoat layer 3 to form a coating film. The resulting coating film was then dried by heating at 130°C for 20 minutes to form an undercoat layer 4 with a thickness of 3.5 μm.

[0189] [Photosensitive drum 7] A photosensitive drum 7 was produced in the same manner as the photosensitive drum 1, except that the protective layer was changed to a protective layer 6 formed as follows.

[0190] (Protective layer 6) 100 parts by mass of tin oxide particles (number average primary particle size 15 nm), 30 parts by mass of a silane coupling agent (trade name: KBM-503, manufactured by Shin-Etsu Silicones Co., Ltd.), and 900 parts by mass of methyl ethyl ketone were placed in a wet sand mill, and glass beads with a diameter of 0.5 mm were added and dispersed for 6 hours. Thereafter, the methyl ethyl ketone and glass beads were filtered off and dried at 60°C to obtain tin oxide particles M1 surface-treated with a silane coupling agent having a methacryloyloxy group.

[0191] 15 parts of the tin oxide particles M1, 85 parts of a compound represented by the following formula (J), a polymerization initiator (product name: Irgacure 819, manufactured by BASF Japan Ltd.), 320 parts of 2-butanol, and 40 parts of tetrahydrofuran were mixed together, and then the mixture was dispersed in a sand mill using glass beads with a diameter of 0.5 mm in an atmosphere of 23±3°C for 6 hours to prepare a surface layer coating liquid.

[0192] This surface layer coating solution was dip-coated onto the charge transport layer 1 to form a coating film, which was then irradiated with ultraviolet light for 1 minute using a metal halide lamp under a nitrogen atmosphere at a distance of 50 mm from the light source to the surface of the photosensitive drum and a lamp output of 4 kW. The resulting coating film was dried at 80°C for 70 minutes to form a protective layer 6 with a thickness of 7 μm.

[0193] [ka]

[0194] [Photosensitive drum 8] A photosensitive drum 8 was produced in the same manner as the photosensitive drum 7, except that the undercoat layer was changed to an undercoat layer 5 formed as follows.

[0195] (Undercoat layer 5) One part of polyamide resin (product name: CM8000, manufactured by Toray Industries, Inc.) was dissolved in 10 parts of methanol. To this solution, three parts of titanium oxide particles (product name: SMT500SAS, average primary particle size 35 μm, manufactured by Teika Corporation) were added, and the mixture was dispersed in a sand mill using glass beads with a diameter of 0.8 mm in an atmosphere of 23±3°C for 10 hours to prepare a coating solution for the undercoat layer.

[0196] The obtained coating liquid for undercoat layer was dip-coated onto the support 1 to form a coating film, and the coating film was dried at 110° C. for 20 minutes to form an undercoat layer 5 with a thickness of 2.0 μm.

[0197] [Photosensitive drum 9] A photosensitive drum 9 was produced in the same manner as the photosensitive drum 1, except that the undercoat layer was changed to an undercoat layer 6 formed as follows.

[0198] (Undercoat layer 6) An undercoat layer coating solution was prepared by dissolving 10 parts of a copolymer nylon resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) and 30 parts of a methoxymethylated nylon resin (trade name: Toresin EF30T, manufactured by Teikoku Chemical Industries Co., Ltd.) in a mixed solvent of 500 parts of methanol and 250 parts of butanol. This undercoat layer coating solution was dip-coated onto the support 1 and dried for 22 minutes in a hot air dryer adjusted to 100°C, thereby forming an undercoat layer 6 with a film thickness of 0.45 μm.

[0199] <Photosensitive drum evaluation> The obtained photosensitive drums 1 to 9 were evaluated as follows.

[0200] [Example 1] A modified Canon Inc. imageRUNNER ADVANCE C5870F (registered trademark) multifunction printer was used, with the solid-state exposure head described above installed in the area where the exposure section had been removed. An organic EL element using a perylene derivative as the light-emitting material was used as the light-emitting element for the light-emitting substrate of the solid-state exposure head. This evaluation device was placed in an environment with a temperature of 23°C and a relative humidity of 5% RH, and the photosensitive drum 1 was attached to it for evaluation. In this evaluation, the voltage applied to the charging member and the current applied to the organic EL element were kept constant.

[0201] (Evaluation of potential fluctuations during repeated use) The potential fluctuation evaluation during repeated use was performed using the above-mentioned evaluation device. A cartridge equipped with a photosensitive drum was attached to the evaluation device, and the photosensitive drum was repeatedly used by passing 100,000 sheets of paper. At the station where the photosensitive drum was installed, 100,000 sheets of A4-size plain paper were repeatedly imaged with a single-color text image at a 1% print rate. The initial dark potential at this time was compared with the dark potential after 100,000 sheets of repeated image formation, and this was taken as the potential fluctuation value (ΔVd). The initial light potential was also compared with the light potential after 100,000 sheets of repeated image formation, and this was taken as the potential fluctuation value (ΔVl). After passing 100,000 sheets of paper, the device was left for 5 minutes, and the developing cartridge was replaced with a potential measuring device. The light potential (Vlb) and dark potential (Vdb) after repeated use were measured. The difference between the dark potential after repeated use and the initial dark potential (Vda) was defined as the dark potential fluctuation (ΔVd = |Vdb| - |Vda|). The difference between the light potential after repeated use and the initial light potential (Vla) was defined as the light potential fluctuation (ΔVl = |Vlb| - |Vla|). In the evaluation using evaluation device 1-2, the light potential fluctuation was measured after repeated use of 300,000 sheets and 500,000 sheets.

[0202] In the present disclosure, when the change in bright area potential (ΔVl) is within 13 V, it is determined that the effect of the present disclosure is achieved, and among these, when the change in bright area potential (ΔVl) is within 8 V, it is determined that it is a particularly excellent level.

[0203] The results of the evaluation are shown in Table 1.

[0204] [Examples 2 to 5, Comparative Examples 1 to 4] The evaluation was carried out in the same manner as in Example 1, except that the photosensitive drums 2 to 9 were each mounted on the evaluation device described in Example 1. The results are shown in Table 1.

[0205] [Table 1]

[0206] In the case of an image forming apparatus using an organic EL element as the light-emitting element and a photosensitive drum having an undercoat layer containing zinc oxide particles and a compound represented by formula (BP), it is found that the change in bright area potential (ΔVl) during long-term repeated use can be suppressed to within 13 V.

[0207] The present disclosure relates to the following configurations.

[0208] (Configuration 1) A photosensitive drum; a plurality of light-emitting elements for emitting exposure light to be irradiated onto the surface of the photosensitive drum; An image forming apparatus having the photosensitive drum has a support, an undercoat layer on the support, a photosensitive layer on the undercoat layer, and a protective layer on the photosensitive layer; The undercoat layer contains zinc oxide particles and a compound represented by the following formula (BP): The light-emitting element is an organic EL element. An image forming apparatus characterized by:

[0209] [ka]

[0210] (In formula (BP), R 1 ~R 10 each independently represents a hydrogen atom, a halogen atom, a hydroxy group, an alkyl group, an alkoxy group, or an amino group. 1 ~R 10 At least one of X is an amino group or a hydroxy group. 1 represents a carbonyl group or a dicarbonyl group.

[0211] (Configuration 2) the photosensitive drum has a surface layer containing a polymer of a compound having a polymerizable functional group, and the protective layer is the surface layer of the photosensitive drum; 2. The image forming apparatus according to claim 1.

[0212] (Configuration 3) the photosensitive drum has a surface layer containing a polymer of a hole transport compound having a polymerizable functional group, the protective layer is a surface layer of the photosensitive drum; 3. The image forming apparatus according to claim 1 or 2.

[0213] (Configuration 4) 4. The image-forming apparatus according to any one of configurations 1 to 3, wherein the polymerizable functional group is a chain-polymerizable functional group.

[0214] (Configuration 5) 5. The image-forming apparatus according to any one of configurations 1 to 4, wherein the compound having a polymerizable functional group is a compound represented by the following formula (CT-1) or (CT-2):

[0215] [ka]

[0216] (In the formula (CT-1), Ar 11 ~Ar 13 are each independently a substituted aryl group or an unsubstituted aryl group. The substituent that the substituted aryl group may have is an alkyl group having 1 to 6 carbon atoms, or a monovalent functional group represented by any one of the following formulae (P-1) to (P-3). However, the compound represented by the formula (CT-1) has at least one monovalent functional group represented by any one of the following formulae (P-1) to (P-3).

[0217] [ka]

[0218] (In the formula (CT-2), Ar 21 ~Ar 24 each independently represents a substituted aryl group or an unsubstituted aryl group. 25represents a substituted arylene group or an unsubstituted arylene group. The substituent that the substituted aryl group may have is an alkyl group having 1 to 6 carbon atoms or a monovalent functional group represented by the following formulas (P-1) to (P-3), and the substituent that the substituted arylene group may have is an alkyl group having 1 to 6 carbon atoms or a monovalent functional group represented by the following formulas (P-1) to (P-3). However, the compound represented by formula (CT-2) has at least one monovalent functional group represented by any of the following formulas (P-1) to (P-3).

[0219] [ka]

[0220] (In the formula (P-1), Z 11 represents a single bond or an alkylene group having 1 to 6 carbon atoms, and X 11 represents a hydrogen atom or a methyl group.

[0221] [ka]

[0222] (In the formula (P-2), Z 21 represents a single bond or an alkylene group having 1 to 6 carbon atoms.

[0223] [ka]

[0224] (In the formula (P-3), Z 31 represents a single bond or an alkylene group having 1 to 6 carbon atoms.

[0225] (Configuration 6) 6. The image-forming apparatus according to any one of Configurations 2 to 5, wherein the compound having a polymerizable functional group is a compound represented by formula (CT-1).

[0226] (Configuration 7) 7. The image forming apparatus according to any one of Configurations 1 to 6, wherein the photosensitive drum has a surface layer containing a hole transporting compound.

[0227] (Configuration 8) 8. The image-forming apparatus according to any one of Configurations 1 to 7, wherein the protective layer contains organic resin particles.

[0228] (Configuration 9) 9. The image forming apparatus according to any one of configurations 1 to 8, wherein a plurality of grooves are formed on the peripheral surface of the photosensitive drum in the approximately circumferential direction of the peripheral surface. [Explanation of symbols]

[0229] 11 Support 12 Undercoat layer 13 Charge generation layer 14 Charge transport layer 15 Surface layer 100 Scanner unit 102 Photosensitive drum 103 Image creation section 104 Fixing section 105 Paper feed / transport section 106 Exposure head 107 Charger 108 Developer 109a, 109b Main body internal paper feed unit 109c External Paper Feed Unit 109d Manual Feed Unit 110 Cash register roller 111 Transfer belt 112 Paper ejection roller 113 Optical Sensor 201 Solid-state exposure head 202 Light-emitting substrate 203 Luminous Point 205 Housing 206 Lens Array

Claims

1. A photosensitive drum; a plurality of light-emitting elements for emitting exposure light to be irradiated onto the surface of the photosensitive drum; An image forming apparatus having the photosensitive drum has a support, an undercoat layer on the support, a photosensitive layer on the undercoat layer, and a protective layer on the photosensitive layer; The undercoat layer contains zinc oxide particles and a compound represented by the following formula (BP): The light-emitting element is an organic EL element. An image forming apparatus characterized by: 【Chemical 1】 (In formula (BP), R １ ~R １０ each independently represents a hydrogen atom, a halogen atom, a hydroxy group, an alkyl group, an alkoxy group, or an amino group. １ ~R １０ At least one of X is an amino group or a hydroxy group. １ represents a carbonyl group or a dicarbonyl group.)

2. the photosensitive drum has a surface layer containing a polymer of a compound having a polymerizable functional group, the protective layer is a surface layer of the photosensitive drum; The image forming apparatus according to claim 1 .

3. the photosensitive drum has a surface layer containing a polymer of a hole transport compound having a polymerizable functional group, the protective layer is a surface layer of the photosensitive drum; The image forming apparatus according to claim 1 .

4. 4. The image forming apparatus according to claim 2, wherein the polymerizable functional group is a chain-polymerizable functional group.

5. 4. The image-forming apparatus according to claim 2, wherein the compound having a polymerizable functional group is a compound represented by the following formula (CT-1) or (CT-2): 【Chemistry 2】 (In the formula (CT-1), Ar １１ ~Ar １３ each independently represents a substituted aryl group or an unsubstituted aryl group. The substituent that the substituted aryl group may have is an alkyl group having 1 to 6 carbon atoms, or a monovalent functional group represented by any one of the following formulas (P-1) to (P-3). However, the compound represented by formula (CT-1) has at least one monovalent functional group represented by any one of the following formulas (P-1) to (P-3). 【Chemistry 3】 (In the formula (CT-2), Ar ２１ ~Ar ２４ each independently represents a substituted aryl group or an unsubstituted aryl group. ２５ represents a substituted arylene group or an unsubstituted arylene group. The substituent that the substituted aryl group may have is an alkyl group having 1 to 6 carbon atoms, or a monovalent functional group represented by the following formulas (P-1) to (P-3), and the substituent that the substituted arylene group may have is an alkyl group having 1 to 6 carbon atoms, or a monovalent functional group represented by the following formulas (P-1) to (P-3). However, the compound represented by formula (CT-2) has at least one monovalent functional group represented by any of the following formulas (P-1) to (P-3). 【Chemistry 4】 (In the formula (P-1), Z １１ represents a single bond or an alkylene group having 1 to 6 carbon atoms; X １１ represents a hydrogen atom or a methyl group. 【Chemistry 5】 (In the formula (P-2), Z ２１ represents a single bond or an alkylene group having 1 to 6 carbon atoms. 【Chemistry 6】 (In the formula (P-3), Z ３１ represents a single bond or an alkylene group having 1 to 6 carbon atoms.

6. 6. The image-forming apparatus according to claim 5, wherein the compound having a polymerizable functional group is a compound represented by formula (CT-1).

7. 2. The image forming apparatus according to claim 1, wherein the photosensitive drum has a surface layer containing a hole transporting compound.

8. The image forming apparatus according to claim 1 , wherein the protective layer contains organic resin particles.

9. 2. The image forming apparatus according to claim 1, wherein a plurality of grooves are formed on the peripheral surface of the photosensitive drum in a substantially circumferential direction of the peripheral surface.

Images