Image forming device

Abstract

To provide an image forming device which makes it possible to suppress a decrease in the absolute value of bright part potential due to a rise of environment temperature and stably form an image.SOLUTION: Provided is an image forming device including a photoconductor drum and a plurality of light-emitting elements for emitting exposure light. The light-emitting elements are organic EL elements having such a characteristic that an emission peak intensity at a wavelength of the strongest peak of an emission spectrum increases due to a temperature rise, and the wavelength of the strongest peak of the emission spectrum of the organic EL elements is 500 nm to 750 nm. The photoconductor drum includes a charge generation layer and a charge transport layer in this order, and the charge generation layer contains a phthalocyanine compound.SELECTED DRAWING: None

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 one type of exposure device that exposes a photosensitive drum (a drum-shaped electrophotographic photosensitive member). A solid-state exposure head has multiple light-emitting points, such as LEDs or organic electroluminescent (EL) light-emitting 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 driving unit compared to laser scanning exposure devices that use a polygon mirror for scanning, making it advantageous for miniaturizing and reducing noise in image forming devices. Patent Document 1 discloses a solid-state exposure head that uses a TFT circuit and an organic electroluminescent (EL) element on a transparent glass substrate.

[0003] On the other hand, photosensitive drums mounted in electrophotographic image forming apparatuses contain a charge generating material. Patent Document 2 discloses a photosensitive drum having a single-layer photosensitive layer containing a phthalocyanine compound as a charge generating material (hereinafter also referred to as a "single-layer photosensitive drum"). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2015-112856 [Patent Document 2] Japanese Patent Application Laid-Open No. 2007-286484 Summary of the Invention [Problem to be solved by the invention]

[0005] However, when a single-layer photosensitive drum and an organic EL element are used as the exposure source of the photosensitive drum, there is room for improvement in the decrease in the absolute value of the light area potential (exposure potential=Vl) when the environmental temperature rises.

[0006] An object of the present disclosure is to provide an image forming apparatus that can suppress a decrease in the absolute value of the bright area potential that occurs with an increase in the environmental temperature, and that enables stable image formation. [Means for solving the problem]

[0007] According to 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 the light-emitting elements are organic EL elements whose emission peak intensity at the wavelength of the most intense peak in their emission spectrum increases with increasing temperature, and the wavelength of the most intense peak in the emission spectrum of the organic EL element is 500 nm or more and 750 nm or less, and the photosensitive drum has a support, a charge generation layer on the support, a charge transport layer on the charge generation layer, and a protective layer on the charge transport layer, and the charge generation layer contains a phthalocyanine compound and at least one selected from the group consisting of a compound represented by the following formula (1), a compound represented by the following formula (2), and a compound represented by the following formula (3).

[0008] [ka]

[0009] (In the formula, Y1 to Y6 each independently represent -CH=N-, -N=CH-, -CH=CH- or -N=N-, and Ar1 to Ar6 each independently represent an aromatic hydrocarbon ring group which may have a substituent or a heterocyclic group which may have a substituent.) [Effects of the Invention]

[0010] According to the present disclosure, it is possible to provide an image forming apparatus that can suppress a decrease in the absolute value of the bright area potential even when the environmental temperature rises, thereby enabling stable image formation. [Brief explanation of the drawings]

[0011] [Figure 1] FIG. 1 is a diagram illustrating an example of an electrophotographic apparatus used in the present disclosure. [Figure 2] FIG. 2 is a diagram illustrating an example of a photosensitive drum used in the present disclosure. [Figure 3] FIG. 2 is a diagram showing an example of an emission spectrum of an organic EL element used in the present disclosure. DETAILED DESCRIPTION OF THE INVENTION

[0012] As a result of investigation by the present inventors, (1) A single-layer photosensitive drum containing a phthalocyanine compound as a charge generating material, and an organic EL element in which the emission peak intensity at the wavelength of the largest peak in the emission spectrum increases with increasing temperature, (2) When an organic EL element having a wavelength of the most intense peak in the emission spectrum of 500 nm or more and 750 nm or less is used as an exposure source for a photosensitive drum, It became clear that a technical issue would arise in which the absolute value of the bright area potential would be more likely to decrease as the ambient temperature increased.

[0013] The present inventors speculate as follows about the reason why the technical problem of the decrease in the absolute value of the bright area potential due to an increase in the environmental temperature occurs.

[0014] Phthalocyanine compounds have a wide absorption range from 500 nm to the long-wavelength region (up to 800 nm). Therefore, in response to the emission of an organic EL element, whose emission spectrum has a wavelength of 500 nm to 750 nm, the phthalocyanine compound in the photosensitive drum generates a charge. The amount of charge generated depends on the intensity of the emitted light. In organic EL elements, whose emission peak intensity at the wavelength of the strongest peak in the emission spectrum increases with increasing temperature, the intensity of the emitted light increases with increasing temperature, and therefore the amount of charge generated by the phthalocyanine compound in the photosensitive drum increases. When the dark potential (charge potential = Vd) of the photosensitive drum is constant, the difference in the intensity of the emitted light leads to a difference in the bright potential, so the absolute value of the bright potential decreases with increasing temperature.

[0015] As a result of the inventors' investigations, it was found that by using a photosensitive drum having a support, a charge generating layer, a charge transport layer, and a protective layer in that order, i.e., a laminated photosensitive drum having a protective layer, the decrease in the absolute value of the bright area potential due to an increase in environmental temperature can be suppressed.

[0016] The present inventors speculate as follows about the reason why the image forming apparatus of the present disclosure is excellent in the effect of suppressing the decrease in the absolute value of the bright area potential due to an increase in the environmental temperature.

[0017] The differences in the configuration between a single-layer photosensitive drum and a multi-layer photosensitive drum with a protective layer are the configuration of the photosensitive layer, etc., and the number of interfaces. A multi-layer photosensitive drum is a photosensitive drum with a multi-layer photosensitive layer that is functionally separated into a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. A single-layer photosensitive drum contains both the charge generation material and the charge transport material in the same single-layer photosensitive layer. Unlike a single-layer photosensitive drum, a multi-layer photosensitive drum has an interface between the charge generation layer and the charge transport layer due to the lamination. Furthermore, by having a protective layer, an interface also exists between the charge transport layer and the protective layer. It is speculated that the presence of these interfaces affects the suppression of a decrease in the absolute value of the light area potential.

[0018] When focusing on the temperature characteristics of the dark potential, the absolute value of the dark potential of a multi-layer photosensitive drum having a protective layer tends to increase with increasing temperature, whereas the temperature dependence of the dark potential of a single-layer photosensitive drum tends to be less than that of a multi-layer photosensitive drum having a protective layer.

[0019] A multilayer photosensitive drum having a protective layer tends to have an increase in the absolute value of the dark potential as the temperature rises. This indicates that dark decay decreases as the temperature rises. The decrease in dark decay with increasing temperature is thought to be caused by the presence of an interface between the charge generation layer and the charge transport layer and an interface between the charge transport layer and the protective layer. The interfaces between the charge generation layer and the charge transport layer and the charge transport layer and the protective layer create energy barriers at these interfaces, which is thought to make it easier for charge generated in the charge generation layer during exposure to accumulate. The presence of this accumulated charge is one of the causes of dark decay during the charging process. As the temperature rises, the charge gains thermal energy, making it easier for the charge to overcome the energy barrier at the interface, and the amount of charge accumulated at the interface is thought to decrease. Therefore, it is thought that the absolute value of the dark potential of a multilayer photosensitive drum having a protective layer tends to increase as the temperature rises.

[0020] When the absolute value of the dark potential increases, the absolute value of the bright potential also increases if the intensity of the light emission is constant. Therefore, it is believed that by combining an exposure source whose intensity of light emission increases with an increase in temperature with a photosensitive drum whose absolute value of the dark potential increases with an increase in temperature, the decrease in the absolute value of the bright potential with an increase in temperature can be suppressed.

[0021] [Image forming device] 1 includes four image forming units 102Y, 102M, 102C, and 102K that form toner images of yellow, magenta, cyan, and black, respectively. The image forming units 102Y, 102M, 102C, and 102K include photosensitive drums 103Y, 103M, 103C, and 103K that can rotate around their respective rotation axes. Chargers 104Y, 104M, 104C, and 104K, solid-state exposure heads 105Y, 105M, 105C, and 105K, and developers 106Y, 106M, 106C, and 106K are provided around the photosensitive drums.

[0022] The solid-state exposure head is also simply called an exposure head.

[0023] <Image formation process> The photosensitive drums 103Y, 103M, 103C, and 103K are uniformly charged by the chargers 104Y, 104M, 104C, and 104K, and then the solid-state exposure heads 105Y, 105M, 105C, and 105K emit exposure light onto the photosensitive drum surfaces. The photosensitive drum surfaces are exposed to light, forming electrostatic latent images. The electrostatic latent images are visualized as toner images of the respective colors by the developers 106Y, 106M, 106C, and 106K, and then transferred to the intermediate transfer belt 107 at the primary transfer stations Ty, Tm, Tc, and Tk.

[0024] The toner images of each color superimposed on the intermediate transfer belt 107 are transferred at once by a secondary transfer roller 109 at a secondary transfer section T2 onto a recording sheet P transported from a paper feed section 101. The recording sheet P onto which the toner images have been transferred is transported to a fixing device 110, where the toner images are fixed by heat and pressure, and then the recording sheet is discharged from a paper discharge section 111.

[0025] <Organic EL element> The light-emitting element of the solid-state exposure head 105 used in the present disclosure is an organic EL element whose emission peak intensity at the wavelength of the most intense peak in the emission spectrum increases with increasing temperature, and whose emission spectrum has a wavelength of the most intense peak in the range of 500 nm to 750 nm.

[0026] The emission spectrum of the organic EL element of the present disclosure may have multiple peaks in the range of 500 nm to 750 nm. When multiple peaks are present, it is preferable that the emission peak intensity at the wavelength of the most intense peak of the organic EL element is at least three times the emission peak intensity at the wavelength of the second most intense peak.

[0027] An exposure head having a light-emitting substrate having a light-emitting chip formed by arranging a plurality of organic EL elements according to the present disclosure can also be used in the present disclosure.

[0028] Instead of an organic EL element having an emission spectrum with a wavelength of the most intense peak in the range of 500 nm to 750 nm, the following solid-state exposure head can also be used in the present disclosure. That is, a solid-state exposure head having an emission spectrum with a wavelength of the most intense peak in the range of 500 nm to 750 nm. Even when a solid-state exposure head having an emission spectrum with a wavelength of the most intense peak in the range of 500 nm to 750 nm is used, there may be multiple peaks in the range of 500 nm to 750 nm. If there are multiple peaks, it is preferable that the emission peak intensity at the wavelength of the exposure head's most intense peak is at least three times the emission peak intensity at the wavelength of the second most intense peak.

[0029] In the present disclosure, the description of the emission spectrum of an organic EL element is the same even if the organic EL element is replaced with a solid-state exposure head, in the parts where the organic EL element can be replaced with a solid-state exposure head.

[0030] In the present disclosure, the peak with the highest intensity refers to the peak with the highest intensity when there is only one peak. When there are multiple peaks, the peak with the highest emission intensity at the peak wavelength in the emission spectrum of the organic EL device of the present disclosure is referred to. The peak wavelength and the wavelength of the peak refer to the wavelength at the top of the peak (peak top).

[0031] The emission peak intensity of the emission spectrum of an organic EL element is determined as follows: The emission spectrum intensity is calculated from the difference between the emitting state and the non-emitting state, and the intensity at the peak wavelength is taken as the emission peak intensity.

[0032] An example of the emission spectrum of an organic EL element is shown in Figure 3. The wavelength of the most intense peak 301 is 600 nm, and the emission peak intensity 303 at the wavelength of the most intense peak is indicated by the arrow. The wavelength of the second most intense peak 302 is 650 nm, and the emission peak intensity 304 at the wavelength of the second most intense peak is indicated by the arrow.

[0033] The wavelength of the most intense peak in the emission spectrum of the organic EL element of the present disclosure is 500 nm or more and 750 nm or less as follows: That is, among a plurality of organic EL elements (=light-emitting elements), it is preferable that the wavelength of the most intense peak in the emission spectrum of 80% or more of the organic EL elements falls within the range of 500 nm or more and 750 nm or less, more preferably 90% or more by number, even more preferably 95% or more by number, and most preferably 100% by number.

[0034] 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.

[0035] [ka]

[0036] [ka]

[0037] 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, organic aluminum complexes such as tris(8-quinolinolato)aluminum, and organic beryllium complexes. However, these are not limited to these. Specific examples are shown below.

[0038] [ka]

[0039] [Photosensitive drum] The photosensitive drum of the present disclosure has a laminated photosensitive layer in which a charge generating layer and a charge transport layer are laminated in this order.

[0040] As an example of the photosensitive drum 103 used in the present disclosure, a support and a laminated photosensitive layer formed on the support are shown in Fig. 2. In Fig. 2, 201 is a support, 202 is an undercoat layer, 203 is a charge generation layer, 204 is a charge transport layer, and 205 is a protective layer.

[0041] <Support> The support is preferably one that is conductive (conductive support), and examples thereof include supports made of metals (alloys) such as aluminum, iron, copper, gold, stainless steel, and nickel, metals with conductive coatings on their surfaces, and insulating supports. Examples of insulating supports include supports made of plastics such as polyester resin, polycarbonate resin, and polyimide resin, as well as glass and paper. Examples of conductive coatings include thin metal films such as aluminum, chromium, silver, and gold, thin films of conductive materials such as indium oxide, tin oxide, and zinc oxide, and thin films of conductive inks containing silver nanowires.

[0042] The support according to the present disclosure has a cylindrical shape. A cylindrical aluminum support is excellent in terms of mechanical strength, electrophotographic properties, and cost. A raw tube may be used as the support as is, but the surface of the raw tube may be subjected to physical treatments such as cutting, honing, and blasting, or to chemical treatments such as anodizing and using an acid, in order to improve electrical properties and suppress interference fringes.

[0043] <Conductive layer> The conductive layer is a layer that may be provided if necessary.

[0044] The conductive layer is a layer that may be disposed on the conductive support and between the conductive support and the photosensitive layer, more specifically, in the layer order of conductive support / conductive layer / undercoat layer / photosensitive layer.

[0045] By providing the conductive layer, scratches and irregularities on the surface of the conductive support can be concealed and light reflection on the surface of the support can be controlled.

[0046] The conductive layer contains conductive particles and a resin.

[0047] Examples of the material of the conductive particles include metal oxides, metals, and carbon black.

[0048] Examples of metal oxides include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, strontium titanate, magnesium oxide, antimony oxide, and bismuth oxide.

[0049] Among these, metals include aluminum, nickel, iron, nichrome, copper, zinc, and silver.

[0050] Of the above materials for the conductive particles, metal oxides are preferred, and titanium oxide, tin oxide, and zinc oxide are particularly preferred.

[0051] Furthermore, with regard to the metal oxide, the surface of the metal oxide may be treated with a silane coupling agent or the like, or may be doped with an element such as phosphorus or aluminum itself or an oxide thereof.

[0052] The conductive particles may have a layered structure including a core material and a coating layer covering the core material. Examples of the core material include titanium oxide, barium sulfate, and zinc oxide. Examples of the coating layer include metal oxides such as tin oxide.

[0053] The coating layer and the surface treated with the silane coupling agent are much thicker than each other.

[0054] When metal oxide particles are used as the conductive particles, the volume average particle size is preferably 1 nm or more and 500 nm or less, and more preferably 3 nm or more and 400 nm or less.

[0055] Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, and alkyd resin.

[0056] Furthermore, the conductive layer may contain silicone oil, resin particles, a masking agent such as titanium oxide, and the like.

[0057] The conductive layer can be obtained by providing a coating film of a coating liquid for conductive layer containing the above-mentioned materials and solvent on a support and drying the coating film.

[0058] Examples of the solvent used in the coating liquid include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0059] Examples of a method for dispersing the conductive particles in the coating liquid for the conductive layer include methods using a paint shaker, a sand mill, a ball mill, and a liquid collision type high-speed disperser.

[0060] The average thickness of the conductive layer is preferably 0.1 μm or more and 50 μm or less, and particularly preferably 3 μm or more and 40 μm or less.

[0061] <Undercoat layer> An undercoat layer having a barrier function or an adhesive function may be provided on the support or the conductive layer, if necessary. The undercoat layer is obtained by dissolving a resin in a solvent to prepare a coating liquid for the undercoat layer, forming a coating film of the coating liquid for the undercoat layer, and drying the coating film. The undercoat layer contains a resin and a substance that improves electrical properties. Each of these will be explained below.

[0062] The undercoat layer contains a resin. The resin may be obtained as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group in a coating liquid to form a coating film (curing by polymerization of the monomer) from the coating liquid.

[0063] Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinylphenol resin, alkyd resin, polyvinyl alcohol resin, polyethylene oxide resin, polypropylene oxide resin, polyamide resin, polyamic acid resin, polyimide resin, polyamideimide resin, and cellulose resin.

[0064] Examples of the polymerizable functional group possessed by the monomer having a polymerizable functional group include an isocyanate group, a blocked isocyanate group, a methylol group, an alkylated methylol group, an epoxy group, a metal alkoxide group, a hydroxyl group, an amino group, a carboxyl group, a thiol group, a carboxylic anhydride group, and a carbon-carbon double bond group.

[0065] Furthermore, for the purpose of improving electrical properties, the undercoat layer contains an electron transporting material, a metal oxide, a metal, etc. Among these, it is preferable to use an electron transporting material or a metal oxide.

[0066] Examples of the electron transport substance include a quinone compound, an imide compound, a benzimidazole compound, a cyclopentadienylidene compound, a fluorenone compound, a xanthone compound, a benzophenone compound, a cyanovinyl compound, an aryl halide compound, a silole compound, a boron-containing compound, etc. An electron transport substance having a polymerizable functional group may be used as the electron transport substance, and the undercoat layer may be formed as a cured film by copolymerizing the electron transport substance with the above-mentioned monomer having the polymerizable functional group.

[0067] Examples of metal oxides include indium tin oxide, tin oxide, indium oxide, titanium oxide, zinc oxide, aluminum oxide, strontium titanate, silicon dioxide, etc. Examples of metals include gold, silver, aluminum, etc.

[0068] The metal oxide contained in the undercoat layer may be surface-treated with a surface treatment agent such as a silane coupling agent.

[0069] The metal oxide surface treatment can be carried out by a common method, such as a dry method or a wet method.

[0070] In the dry method, a metal oxide is stirred in a mixer capable of high-speed stirring, such as a Henschel mixer, while an alcohol aqueous solution, an organic solvent solution, or an aqueous solution containing a surface treatment agent is added to the metal oxide to uniformly disperse the mixture, followed by drying.

[0071] In the wet method, the metal oxide and the surface treatment agent are stirred in a solvent or dispersed in a sand mill using glass beads or the like, and after dispersion, the solvent is removed by filtration or vacuum distillation. After the solvent is removed, it is preferable to further bake the mixture at 100°C or higher.

[0072] The undercoat layer may further contain additives, for example, known materials such as metal powder such as aluminum, conductive substances such as carbon black, metal chelate compounds, and organometallic compounds.

[0073] The undercoat layer can be formed by preparing a coating solution for the undercoat layer containing the above-mentioned materials and solvent, forming the coating film on the support or the conductive layer, and drying and / or curing it.

[0074] Examples of solvents that can be used in the coating liquid for the undercoat layer include organic solvents such as alcohols, sulfoxides, ketones, ethers, esters, halogenated aliphatic hydrocarbons, and aromatic compounds. Among these, it is preferable to use alcohol-based and ketone-based solvents.

[0075] 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.

[0076] When an undercoat layer is used, the average thickness thereof is preferably from 0.05 μm to 50 μm, and more preferably from 0.3 μm to 25 μm.

[0077] <Charge generation layer> Directly over the undercoat layer is a charge generating layer.

[0078] The charge generating layer of the present disclosure contains a phthalocyanine compound. Examples of the phthalocyanine compound in the present disclosure include metal phthalocyanines and metal-free phthalocyanines. Among the metal phthalocyanines, at least one selected from the group consisting of oxytitanium phthalocyanine, chlorogallium phthalocyanine, and hydroxygallium phthalocyanine is preferred.

[0079] The oxytitanium phthalocyanine is preferably an oxytitanium phthalocyanine crystal having a crystalline form that exhibits strong peaks at Bragg angles (2θ±0.2°) of 9.0°, 14.2°, 23.9°, and 27.1° in CuKα characteristic X-ray diffraction, or an oxytitanium phthalocyanine crystal having strong peaks at Bragg angles (2θ±0.2°) of 9.5°, 9.7°, 11.7°, 15.0°, 23.5°, 24.1°, and 27.3°.

[0080] The chlorogallium phthalocyanine is preferably a chlorogallium phthalocyanine crystal having strong peaks at Bragg angles (2θ±0.2°) of 7.4°, 16.6°, 25.5°, and 28.3° in CuKα characteristic X-ray diffraction; a chlorogallium phthalocyanine crystal having strong peaks at Bragg angles (2θ±0.2°) of 6.8°, 17.3°, 23.6°, and 26.9°; or a chlorogallium phthalocyanine crystal having strong peaks at Bragg angles (2θ±0.2°) of 8.7°, 9.2°, 17.6°, 24.0°, 27.4°, and 28.8°.

[0081] The hydroxygallium phthalocyanine is preferably a hydroxygallium phthalocyanine crystal having strong peaks at Bragg angles (2θ±0.2°) of 7.3°, 24.9°, and 28.1° in CuKα characteristic X-ray diffraction, or a hydroxygallium phthalocyanine crystal having strong peaks at Bragg angles (2θ±0.2°) of 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3°.

[0082] The charge generating layer of the present disclosure contains at least one compound selected from the group consisting of a compound represented by the following formula (1), a compound represented by the following formula (2), and a compound represented by the following formula (3).

[0083] [ka]

[0084] (In the formula, Y1 to Y6 each independently represent -CH=N-, -N=CH-, -CH=CH- or -N=N-, and Ar1 to Ar6 each independently represent an aromatic hydrocarbon ring group which may have a substituent or a heterocyclic group which may have a substituent.)

[0085] Examples of the compound represented by formula (1) include the following compounds.

[0086] [ka]

[0087] [ka]

[0088] [ka]

[0089] [ka]

[0090] [ka]

[0091] [ka]

[0092] Examples of the compound represented by formula (2) include the following compounds.

[0093] [ka]

[0094] [ka]

[0095] [ka]

[0096] [ka]

[0097] [ka]

[0098] [ka]

[0099] Examples of the compound represented by formula (3) include the following compounds.

[0100] [ka]

[0101] [ka]

[0102] [ka]

[0103] [ka]

[0104] [ka]

[0105] [ka]

[0106] Ar in the formula (1), the formula (2), and the formula (3) 1 ~Ar 6 is more preferably an aromatic hydrocarbon ring group or a heterocyclic group having at least one substituent selected from the group consisting of a cyano group, a nitro group, and a halogen atom.

[0107] The content of at least one compound selected from the group consisting of the compound represented by formula (1), the compound represented by formula (2), and the compound represented by formula (3) is preferably 0.1% by mass or more and 10% by mass or less of the phthalocyanine compound contained in the charge generating layer.

[0108] Examples of binder resins used in the charge generating layer include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic acid esters, methacrylic acid esters, vinylidene fluoride, and trifluoroethylene, as well as polyvinyl alcohol resins, polyvinyl acetal resins, polycarbonate resins, polyester resins, polysulfone resins, polyphenylene oxide resins, polyurethane resins, cellulose resins, phenolic resins, melamine resins, silicon resins, and epoxy resins. Among these, polyester resins, polycarbonate resins, and polyvinyl acetal resins are preferred, with polyvinyl acetal being more preferred.

[0109] In the charge generating layer, the ratio of the charge generating material to the binder resin (charge generating material / binder resin) is preferably in the range of 10 / 1 to 1 / 10, and more preferably in the range of 5 / 1 to 1 / 5. Examples of the solvent used in the coating liquid for the charge generating layer include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon solvents.

[0110] The thickness of the charge generating layer is preferably 0.05 μm or more and 5 μm or less.

[0111] The ionization potential of the phthalocyanine compound is preferably 5.2 eV or more and 5.7 eV or less.

[0112] When multiple phthalocyanine compounds are used, the value of the ionization potential of the phthalocyanine compounds is the value of the substance with the smallest absolute value of the ionization potential. When multiple phthalocyanine compounds are used, the value of the ionization potential is preferably in the range of 5.2 eV to 5.7 eV.

[0113] The ionization potential was measured by measuring the threshold energy for emitting electrons using an atmospheric photoelectron spectrometer (trade name: AC-3) manufactured by Riken Keiki Co., Ltd.

[0114] <Charge transport layer> The charge transport layer can be obtained by dissolving or dispersing the second charge transport compound and, if necessary, a binder resin in a solvent to prepare a coating liquid for the charge transport layer, forming a coating film of the coating liquid for the charge transport layer, and drying the coating liquid. If a protective layer, which will be described later, is not provided, the charge transport layer becomes the surface layer of the photosensitive drum.

[0115] Examples of the second charge transport compound include triarylamine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, and triarylmethane compounds. Polymers having groups derived from these compounds in the main chain or side chain are also included. Among these, preferred second charge transport compounds are triarylamine compounds, styryl compounds, and benzidine compounds, with triarylamine compounds being particularly preferred. The second charge transport compounds may be used alone or in combination of one or more of them.

[0116] The ionization potential of the second charge transporting compound is preferably 5.2 eV or more and 5.7 eV or less.

[0117] When a plurality of second charge transport compounds are used, the value of the ionization potential of the second charge transport compounds is the value of the substance with the smallest absolute value of the ionization potential. When a plurality of second charge transport compounds are used, the value of the ionization potential is preferably in the range of 5.2 eV to 5.7 eV.

[0118] The difference (|Ip1-Ip2|) between the ionization potential (Ip1) of the phthalocyanine compound in the charge generation layer and the ionization potential (Ip2) of the second charge transport compound in the charge transport layer is preferably in the range of 0 eV to 0.2 eV. When the ionization potential is in this range, the energy barrier at the interface between the charge generation layer and the charge transport layer is appropriately adjusted, which is thought to suppress the decrease in the absolute value of the bright area potential due to an increase in environmental temperature.

[0119] Examples of binder resins used in the charge transport layer include resins (insulating resins) such as polyvinyl butyral resin, polyvinyl acetal resin, polyester resin, polycarbonate resin, polyester resin, polyvinyl acetate resin, polysulfone resin, polystyrene resin, phenoxy resin, polyvinyl acetate resin, acrylic resin, phenoxy resin, polyacrylamide resin, polyamide resin, polyvinylpyridine resin, cellulose resin, urethane resin, epoxy resin, agarose resin, cellulose resin, casein resin, polyvinyl alcohol resin, polyvinylpyrrolidone resin, vinylidene chloride resin, acrylonitrile copolymer, and polyvinyl benzal resin. Organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinyl anthracene, and polyvinylpyrene can also be used.

[0120] <Protective layer> It is preferable to provide a protective layer directly on the charge transport layer as needed on the photosensitive layer to provide durability, charging ability, etc. The interface between the photosensitive layer and the protective layer improves the effect of suppressing the decrease in the absolute value of the bright area potential due to temperature rise.

[0121] The protective layer can be obtained by dissolving a resin in an organic solvent to prepare a coating solution for the protective layer, forming a coating film of the coating solution for the protective layer, and drying the coating film. Alternatively, the protective layer can be formed by curing the coating film with heat, electron beams, ultraviolet rays, or the like.

[0122] Resins used in the protective layer include polyvinyl butyral resin, polyester resin, polycarbonate resin (such as polycarbonate Z resin and modified polycarbonate resin), nylon resin, polyimide resin, polyarylate resin, polyurethane resin, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile copolymer, and melamine-guanamine resin.

[0123] The protective layer preferably contains a first charge transporting compound. The first charge transporting compound is preferably a hole transporting compound. The first charge transporting compound is preferably a hole transporting compound having a polymerizable functional group, and the protective layer (surface layer) preferably contains a polymer of the first charge transporting compound having a polymerizable functional group.

[0124] It is also preferable to form the protective layer by curing a monomer having hole transport ability using various polymerization reactions or crosslinking reactions. Specifically, it is preferable to form the protective layer by polymerizing or crosslinking a charge transport compound having a chain-polymerizable functional group and curing it. When forming the protective layer, in addition to the charge transport compound having a chain-polymerizable functional group, a charge transport compound having another chain-polymerizable functional group may be polymerized, or a non-charge transport compound having another chain-polymerizable functional group may be polymerized.

[0125] 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).

[0126] [ka]

[0127] 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).

[0128] [ka]

[0129] 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).

[0130] [ka]

[0131] 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.

[0132] [ka]

[0133] In the formula (P-2), Z 21 represents a single bond or an alkylene group having 1 to 6 carbon atoms.

[0134] [ka]

[0135] In the formula (P-3), Z 31 represents a single bond or an alkylene group having 1 to 6 carbon atoms.

[0136] The ionization potential of the first charge transporting compound used in the protective layer is preferably 5.2 eV or more and 5.7 eV or less.

[0137] When a plurality of first charge transport compounds are used, the value of the ionization potential of the first charge transport compounds is the value of the substance with the smallest absolute value of the ionization potential. When a plurality of first charge transport compounds are used, the value of the ionization potential is preferably in the range of 5.2 eV to 5.7 eV.

[0138] The difference (|Ip2-Ip3|) between the ionization potential (Ip2) of the second charge transport compound in the charge transport layer and the ionization potential (Ip3) of the first charge transport compound in the protective layer is preferably in the range of 0 eV to 0.2 eV. When the ionization potential is in this range, the energy barrier between the charge transport layer and the protective layer is appropriately adjusted, which is thought to be effective in suppressing a decrease in the absolute value of the bright area potential due to an increase in environmental temperature.

[0139] The protective layer may also contain conductive particles, ultraviolet absorbers, lubricating particles such as fluorine-containing resin particles, etc. The conductive particles are preferably metal oxide particles such as tin oxide particles. The thickness of the protective layer is preferably 0.05 to 20 μm.

[0140] The coating method for each layer may be a dip coating method (dipping method), a spray coating method, a spinner coating method, a bead coating method, a blade coating method, a beam coating method, etc. Among these, the dip coating method is preferred from the viewpoints of efficiency and productivity.

[0141] The protective layer preferably contains organic resin particles, which can improve the abrasion resistance of the protective layer.

[0142] Examples of organic resin particles include fluorine atom-containing resin particles, silicone resin particles, polystyrene resin particles, and polyethylene resin particles.

[0143] Among these, fluorine atom-containing resin particles are preferred from the viewpoint of dispersibility.

[0144] 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.

[0145] 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.

[0146] 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.

[0147] The protective layer may also contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, etc. Specific examples include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, polystyrene resin particles, polyethylene resin particles, and boron nitride particles.

[0148] 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.

[0149] 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.

[0150] <Surface treatment of photosensitive drum> In the present disclosure, it is preferable to perform a surface treatment on the photosensitive drum. Having a surface-treated surface layer can further stabilize the behavior of a cleaning means (cleaning blade) that comes into contact with the photosensitive drum. Examples of surface treatment methods include a method in which a mold with 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 approximate 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, providing concave or convex portions on the surface layer of the photosensitive drum can further stabilize the behavior of a cleaning means that comes into contact with the photosensitive drum.

[0151] The recesses or protrusions may be formed over the entire surface of the photosensitive drum or may be formed on only a part of the surface of the photosensitive drum. When the recesses or protrusions are formed on only a part of the surface of the photosensitive drum, it is preferable that the recesses or protrusions are formed over at least the entire area of ​​contact with the cleaning means (cleaning blade).

[0152] When forming recesses, a mold having protrusions corresponding to the recesses is pressed against the surface of the photosensitive drum to transfer the shape, thereby forming the recesses on the surface of the photosensitive drum. [Example]

[0153] The technology of the present disclosure will be described in more detail below with reference to specific examples, but is not limited to these. In the following, "parts" means "parts by mass." The film thickness of each layer of the photosensitive drum in the examples and comparative examples was determined by a method using an eddy current film thickness meter, a method using a spectral interference film thickness meter, or a method converting the mass per unit area into specific gravity. The eddy current film thickness meter used was a Fischerscope (manufactured by Fischer Instruments), and the spectral interference film thickness meter used was a C-13027-11 (manufactured by Hamamatsu Photonics).

[0154] [Example 1] (Support) A cylindrical aluminum cylinder (JIS-A3003, aluminum alloy, outer diameter 30 mm, length 357.5 mm, wall thickness 0.7 mm) was used as a 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 for degreasing, and this was used as a support.

[0155] (undercoat layer) Zinc oxide particles (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.

[0156] 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.

[0157] 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.

[0158] The obtained coating liquid for undercoat layer was dip-coated onto the support to form a coating film, and the coating film was dried at 160° C. for 30 minutes to form an undercoat layer with a thickness of 18 μm.

[0159] (charge generation layer) Four parts of hydroxygallium phthalocyanine crystals (charge generating material) with a crystalline form and an ionization potential of 5.5 eV, which exhibit 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. After the dispersion process, 100 parts of ethyl acetate was added to prepare a coating solution for a charge generating layer.

[0160] This charge generating layer coating liquid was dip coated onto the undercoat layer, and the resulting coating was dried at 90° C. for 10 minutes to form a charge generating layer having a thickness of 0.15 μm.

[0161] [ka]

[0162] (charge transport layer) A coating solution for a charge transport layer was prepared by dissolving 60 parts of a second charge transport compound having an ionization potential of 5.4 eV and represented by the following formula (L), 30 parts of a second charge transport compound having an ionization potential of 5.5 eV and represented by the following formula (M), 10 parts of a second charge transport compound having an ionization potential of 5.6 eV and 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.

[0163] This charge transport layer coating solution was dip coated onto the charge generation layer to form a coating film, and the resulting coating film was dried at 115° C. for 50 minutes to form a charge transport layer with a thickness of 18 μm.

[0164] [ka]

[0165] [ka]

[0166] [ka]

[0167] [ka]

[0168] (In formula (O), 0.95 and 0.05 are the molar ratios (copolymerization ratios) of the two structural units.)

[0169] (protective layer) 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.

[0170] [ka]

[0171] 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.

[0172] (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.

[0173] 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" (manufactured by Tosoh Corporation) with a pore size of 0.2 μm to obtain a sample solution. The sample solution is adjusted 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

[0174] 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.

[0175] 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.

[0176] 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.

[0177] To the obtained polytetrafluoroethylene resin particle dispersion, 75.4 parts of a first charge transport compound represented by the following formula (B) and having an ionization potential of 5.6 eV, 21.9 parts of a compound represented by the following formula (C), and 100 parts of 1-propanol were added. The mixture was then filtered using 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).

[0178] [ka]

[0179] [ka]

[0180] This protective layer coating solution was dip-coated onto the charge transport layer 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, under a nitrogen atmosphere, the coating film was heat-treated for 15 seconds to a temperature of 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 to a temperature of 105°C to form a surface layer (protective layer) with a thickness of 5 μm.

[0181] In this way, a photosensitive drum 1 having a support and a surface layer before surface polishing was produced.

[0182] <Surface treatment of photosensitive drum> Before surface polishing, the photosensitive drum surface was provided with a circumferentially streaked surface. Both ends of the photosensitive drum were gripped, and the drum was rotated in the circumferential direction, and polished by pressing an abrasive sheet against it. The abrasive sheet used was GC3000 manufactured by Riken Corundum Co., Ltd.

[0183] By the above polishing, a plurality of grooves were formed in the approximate circumferential direction of the peripheral surface of the photosensitive drum.

[0184] The surface shape of the photosensitive drum after surface polishing was measured. The maximum height Rmax according to JIS B 0601 1982 was measured using a surface roughness measuring instrument, Surfcorder SE3500, manufactured by Kosaka Laboratory Co., Ltd., and the Rmax was found to be 0.75 μm.

[0185] [Example 2] Photosensitive drum 2 was obtained in the same manner as in Example 1, except that the hydroxygallium phthalocyanine crystal, which is the charge generating material of the charge generating layer, was changed to an X-type metal-free phthalocyanine crystal (ionization potential 5.4 eV), and the surface of the photosensitive drum was not treated.

[0186] [Example 3] In Example 1, the hydroxygallium phthalocyanine crystal, which is the charge generating material of the charge generating layer, was changed to an oxytitanium phthalocyanine crystal (ionization potential 5.6 eV) with a crystalline form that has strong peaks at Bragg angles (2θ±0.2°) of 9.0°, 14.2°, 23.9°, and 27.1° in CuKα characteristic X-ray diffraction, and photosensitive drum 3 was obtained in the same manner except that the surface of the photosensitive drum was not treated.

[0187] [Example 4] In Example 1, the hydroxygallium phthalocyanine crystal, which is the charge generating material of the charge generating layer, was changed to a chlorogallium phthalocyanine crystal (ionization potential 5.5 eV) with a crystalline form that has strong peaks at Bragg angles (2θ±0.2°) of 7.4°, 16.6°, 25.5°, and 28.3° in CuKα characteristic X-ray diffraction, and photosensitive drum 4 was obtained in the same manner except that the surface of the photosensitive drum was not treated.

[0188] [Example 5] Photosensitive drum 5 was obtained in the same manner as in Example 1, except that a conductive layer was provided on the support as follows, the undercoat layer was changed as follows, the protective layer was changed as follows, and the surface of the photosensitive drum was not treated.

[0189] (Conductive layer) A conductive layer coating solution was prepared by dispersing 600 parts of a powder of barium sulfate particles coated with a tin oxide coating (trade name: Pastran PC1, manufactured by Mitsui Mining & Smelting Co., Ltd.), 150 parts of titanium oxide (trade name: TITANIX JR, manufactured by Teika Corporation), 430 parts of a resol-type phenolic resin (trade name: Phenolite J-325, manufactured by Dainippon Ink and Chemicals, Inc., 70% solids), 0.15 parts of silicone oil (trade name: SH28PA, manufactured by Toray Silicones Co., Ltd.), 36 parts of a silicone resin (trade name: Tospearl 120, manufactured by Toshiba Silicones Co., Ltd.), and a solution consisting of 500 parts 2-methoxy-1-propanol and 500 parts methanol in a ball mill for approximately 20 hours. The conductive layer coating solution thus prepared was applied to a support by immersion and cured by heating at 150°C for 50 minutes to form a conductive layer with a thickness of 15 μm.

[0190] (undercoat layer) A solution of 40 parts of methoxymethylated 6 nylon resin (trade name: Torezin EF-30T, manufactured by Teikoku Chemical Co., Ltd.) dissolved in 600 parts of methanol was dip-coated onto the conductive layer, and the solution was dried by heating at 100°C for 20 minutes to form an undercoat layer with a thickness of 0.45 μm.

[0191] (protective layer) 16.25 parts of the compound represented by formula (B), 8.75 parts of a first charge-transporting compound represented by formula (D) below having an ionization potential of 5.6 eV, 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.

[0192] This protective layer coating solution was dip-coated onto the charge transport layer 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, under a nitrogen atmosphere, the coating film was heat-treated for 15 seconds to a temperature of 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 to a temperature of 105°C to form a surface layer (protective layer) with a thickness of 5 μm.

[0193] [ka]

[0194] [Example 6] Photosensitive drum 6 was obtained in the same manner as in Example 2, except that the charge transport layer was changed as follows and the surface of the photosensitive drum was not subjected to any surface treatment.

[0195] (charge transport layer) A coating solution for a charge transport layer was prepared by dissolving 100 parts of a second charge transport compound having an ionization potential of 5.7 eV and represented by the following formula (P), 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 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.

[0196] This charge transport layer coating solution was dip coated onto the charge generation layer to form a coating film, and the resulting coating film was dried at 115° C. for 50 minutes to form a charge transport layer with a thickness of 18 μm.

[0197] [ka]

[0198] [Example 7] Photosensitive drum 7 was obtained in the same manner as in Example 1, except that the charge transport layer was changed as follows and the surface of the photosensitive drum was not subjected to any surface treatment.

[0199] (charge transport layer) A coating solution for a charge transport layer was prepared by dissolving 100 parts of a second charge transport compound having an ionization potential of 5.3 eV and represented by the following formula (Q), 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 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.

[0200] This charge transport layer coating solution was dip coated onto the charge generation layer to form a coating film, and the resulting coating film was dried at 115° C. for 50 minutes to form a charge transport layer with a thickness of 18 μm.

[0201] [ka]

[0202] [Comparative Example 1] (Support) A cylindrical aluminum cylinder (JIS-A3003, aluminum alloy, outer diameter 30 mm, length 357.5 mm, wall thickness 0.7 mm) was used as a 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 for degreasing, and this was used as a support.

[0203] (undercoat layer) Zinc oxide particles (specific surface area: 19 m 2 / g, powder resistance: 4.7×10 6100 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.

[0204] 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.

[0205] 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.

[0206] The obtained coating liquid for undercoat layer was dip-coated onto the support to form a coating film, and the coating film was dried at 160° C. for 30 minutes to form an undercoat layer with a thickness of 18 μm.

[0207] (single-layer photosensitive layer) The following materials were prepared: Two hydroxygallium phthalocyanine crystals (ionization potential 5.5 eV) in a crystalline form with strong peaks at Bragg angles 2θ±0.2° (7.4° and 28.1°) in CuKα characteristic X-ray diffraction. 30 parts of a compound having an ionization potential of 5.4 eV and represented by formula (L) as a hole transporting material 5 parts of 3,3',5,5'-tetra-tert-butyl-4,4'-diphenoquinone (Tokyo Chemical Industry Co., Ltd.) as an electron transport material 40 parts of bisphenol Z polycarbonate resin (product name: Iupilon Z400, manufactured by Mitsubishi Engineering Plastics Corporation) 140 parts tetrahydrofuran and 140 parts o-xylene as solvents

[0208] These were placed in a sand mill using glass beads with a diameter of 1 mm and subjected to a dispersion treatment for 4 hours to prepare a coating solution for the photosensitive layer.

[0209] This coating solution for the photosensitive layer was dip-coated onto the undercoat layer to form a coating film, and the coating film was dried at 110° C. for 50 minutes to form a photosensitive layer with a thickness of 25 μm.

[0210] In this way, the photosensitive drum 8 was obtained.

[0211] Comparative Example 2 A photosensitive drum 9 was obtained in the same manner as in Example 2, except that no protective layer was provided and no surface treatment was applied to the photosensitive drum.

[0212] Comparative Example 3 A photosensitive drum 10 was obtained in the same manner as in Example 2, except that the compound represented by formula (K) was not added to the coating liquid for the charge generating layer, and the surface of the photosensitive drum was not treated.

[0213] [evaluation] For the evaluation, a modified Canon Inc. multifunction printer (product name: imageRUNNER ADVANCE C5870F) was used. The modification involved removing the exposure section of the multifunction printer and installing an organic EL element using a perylene derivative as the light-emitting material as a light-emitting element for the light-emitting substrate of the solid-state exposure head mentioned in the above example. The modified printer was equipped with a pre-exposure device. In this evaluation, the voltage applied to the charging member and the current applied to the organic EL element were kept constant.

[0214] The organic EL element used had an emission spectrum with the most intense peak wavelength at 600 nm and the second most intense peak wavelength at 650 nm. The emission peak intensity at 600 nm was more than three times that at 650 nm within an ambient temperature range of 15°C to 32°C. When the ambient temperature of this organic EL element increased from 15°C to 32°C, the emission peak intensity at 600 nm increased at a rate of 0.3% per degree Celsius.

[0215] The solid-state exposure head constructed as described above had an emission spectrum with the most intense peak wavelength at 600 nm and the second most intense peak wavelength at 650 nm. Within an ambient temperature range of 15°C to 32°C, the emission peak intensity at 600 nm was three times that of the 650 nm peak intensity. When the ambient temperature of this solid-state exposure head rose from 15°C to 32°C, the emission peak intensity at 600 nm increased at a rate of 0.3% per degree Celsius.

[0216] The light area potential of each photosensitive drum was measured by the following method. The developer was removed from the process cartridge of the evaluation device, a potential measurement probe (trade name: model 6000B-8, manufactured by Trek) was placed at the development position, and the light area potential of the photosensitive drum was measured using a surface potentiometer (model 344, manufactured by Trek). The position of the potential measurement probe relative to the photosensitive drum was the center of the photosensitive drum in the axial direction, and the distance between the surface of the photosensitive drum and the measurement surface of the potential measurement probe was 3 mm.

[0217] The evaluation device was placed in an environment with a temperature of 15°C and a humidity of 50% RH. The voltage applied to the charging member was adjusted so that the dark area potential of the photosensitive drum was -500 V, and the amount of emitted light was adjusted so that the bright area potential when irradiated with light emitted from the organic EL element was -250 V. The evaluation device was then placed in an environment with a temperature of 32°C and a humidity of 50% RH, and the bright area potential Vl of the photosensitive drum was measured without changing the applied voltage or the amount of emitted light. The change in bright area potential (ΔVl = |-250 V|-|Vl|) between the environment with a temperature of 15°C and a humidity of 50% RH and the environment with a temperature of 32°C and a humidity of 50% RH was determined, and the results were evaluated according to the following evaluation criteria. Table 1 shows the results.

[0218] (Evaluation criteria for the amount of change in bright area potential) The smaller the value of ΔVl, the better. A: ΔVl is 0V or more and less than 5V B: ΔVl is 5V or more and less than 10V C: ΔVl is 10V or more and less than 15V D: ΔVl is 15V or more and less than 20V E: ΔVl is 20V or more

[0219] [Table 1]

[0220] The present disclosure relates to the following configurations.

[0221] (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 light-emitting element is an organic EL element in which the emission peak intensity at the wavelength of the strongest peak in the emission spectrum increases with increasing temperature, the wavelength of the most intense peak in the emission spectrum of the organic EL element is 500 nm or more and 750 nm or less; the photosensitive drum has a support, a charge generating layer on the support, a charge transport layer on the charge generating layer, and a protective layer on the charge transport layer; the charge generating layer comprises a phthalocyanine compound, and The compound contains at least one selected from the group consisting of a compound represented by the following formula (1), a compound represented by the following formula (2), and a compound represented by the following formula (3), An image forming apparatus characterized by:

[0222] [ka]

[0223] (In the formula, Y1 to Y6 each independently represent -CH=N-, -N=CH-, -CH=CH- or -N=N-, and Ar1 to Ar6 each independently represent an aromatic hydrocarbon ring group which may have a substituent or a heterocyclic group which may have a substituent.)

[0224] (Configuration 2) 2. The image-forming apparatus according to claim 1, wherein Ar1 to Ar6 are aromatic hydrocarbon ring groups or heterocyclic groups having at least one substituent selected from the group consisting of a cyano group, a nitro group, and a halogen atom.

[0225] (Configuration 3) 3. The image forming apparatus according to claim 1, wherein the phthalocyanine compound is chlorogallium phthalocyanine or hydroxygallium phthalocyanine.

[0226] (Configuration 4) 4. The image forming apparatus according to any one of configurations 1 to 3, wherein the emission peak intensity at the wavelength of the most intense peak of the organic EL element is at least three times the emission peak intensity at the wavelength of the second most intense peak.

[0227] (Configuration 5) the protective layer contains a first charge transporting compound, the protective layer is a surface layer of the photosensitive drum; 5. The image forming apparatus according to any one of configurations 1 to 4.

[0228] (Configuration 6) the protective layer contains a polymer of a first charge transporting compound having a polymerizable functional group, the protective layer is a surface layer of the photosensitive drum; 6. The image forming apparatus according to any one of configurations 1 to 5.

[0229] (Configuration 7) the charge transport layer contains a second charge transport compound, a difference (|Ip1-Ip2|) between an ionization potential (Ip1) of the phthalocyanine compound and an ionization potential (Ip2) of the second charge transport compound is 0 eV or more and 0.2 eV or less; 7. The image forming apparatus according to any one of the first to sixth aspects.

[0230] (Configuration 8) the charge transport layer contains a second charge transport compound, a difference (|Ip2-Ip3|) between an ionization potential (Ip2) of the second charge transport compound and an ionization potential (Ip3) of the first charge transport compound is 0 eV or more and 0.2 eV or less; The image forming apparatus according to any one of the first to seventh embodiments.

[0231] (Configuration 9) 9. The image-forming apparatus according to any one of configurations 1 to 8, wherein the protective layer contains organic resin particles.

[0232] (Configuration 10) 10. The image forming apparatus according to any one of configurations 1 to 9, wherein a plurality of grooves are formed on the peripheral surface of the photosensitive drum in the approximate circumferential direction of the peripheral surface.

[0233] (Configuration 11) 11. The image-forming apparatus according to any one of configurations 1 to 10, wherein the first charge-transporting compound having a polymerizable functional group is a compound represented by the following formula (CT-1) or (CT-2):

[0234] [ka]

[0235] (In the formula (CT-1), Ar 11 ~Ar 13are 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).

[0236] [ka]

[0237] (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).

[0238] [ka]

[0239] (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.

[0240] [ka]

[0241] (In the formula (P-2), Z21 represents a single bond or an alkylene group having 1 to 6 carbon atoms.

[0242] [ka]

[0243] (In the formula (P-3), Z 31 represents a single bond or an alkylene group having 1 to 6 carbon atoms.

[0244] (Configuration 12) 12. The image-forming apparatus according to any one of configurations 1 to 11, wherein the compound having a polymerizable functional group is a compound represented by formula (CT-1). [Explanation of symbols]

[0245] 103 Photosensitive drum 105 Solid-state exposure head 201 Support 202 Undercoat layer 203 Charge generation layer 204 Charge transport layer 205 Protective layer 301 Most intense peak 302 Second most intense peak 303 Emission peak intensity at the wavelength of the most intense peak 304 Emission peak intensity at the wavelength of the second most intense peak

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 light-emitting element is an organic EL element in which the emission peak intensity at the wavelength of the strongest peak in the emission spectrum increases with increasing temperature, the wavelength of the most intense peak in the emission spectrum of the organic EL element is 500 nm or more and 750 nm or less; the photosensitive drum has a support, a charge generating layer on the support, a charge transport layer on the charge generating layer, and a protective layer on the charge transport layer; the charge generating layer comprises a phthalocyanine compound, and The composition contains at least one compound selected from the group consisting of a compound represented by the following formula (1), a compound represented by the following formula (2), and a compound represented by the following formula (3): An image forming apparatus characterized by: 【Chemical 1】 (In the formula, Y １ ~Y ６ each independently represents -CH=N-, -N=CH-, -CH=CH- or -N=N-, Ar １ ~Ar ６ each independently represents an aromatic hydrocarbon ring group which may have a substituent or a heterocyclic group which may have a substituent).

2. The Ar １ ~Ar ６ 2. The image-forming apparatus according to claim 1, wherein is an aromatic hydrocarbon ring group or a heterocyclic group having at least one substituent selected from the group consisting of a cyano group, a nitro group, and a halogen atom.

3. 2. The image forming apparatus according to claim 1, wherein the phthalocyanine compound is chlorogallium phthalocyanine or hydroxygallium phthalocyanine.

4. 2. The image forming apparatus according to claim 1, wherein the emission peak intensity at the wavelength of the highest peak intensity of said organic EL element is at least three times the emission peak intensity at the wavelength of the second highest peak intensity.

5. the protective layer contains a first charge transporting compound, the protective layer is a surface layer of the photosensitive drum; The image forming apparatus according to claim 1 .

6. the protective layer contains a polymer of a first charge 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 .

7. the charge transport layer contains a second charge transport compound, a difference (|Ip1-Ip2|) between an ionization potential (Ip1) of the phthalocyanine compound and an ionization potential (Ip2) of the second charge transport compound is 0 eV or more and 0.2 eV or less; The image forming apparatus according to claim 2 .

8. the charge transport layer contains a second charge transport compound, a difference (|Ip2-Ip3|) between an ionization potential (Ip2) of the second charge transport compound and an ionization potential (Ip3) of the first charge transport compound is 0 eV or more and 0.2 eV or less; 6. The image forming apparatus according to claim 4.

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

10. 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.

11. 6. The image-forming apparatus according to claim 5, wherein the first charge-transporting 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 from 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.

12. 12. The image-forming apparatus according to claim 11, wherein the compound having a polymerizable functional group is a compound represented by formula (CT-1).

Images