Image forming apparatus

Abstract

To provide an image forming apparatus that prevents an image defect caused by exposure unevenness even when the apparatus has a photoconductor drum containing inorganic fine particles in its surface.SOLUTION: An image forming apparatus has a photoconductor drum, a light emitting element, a lens array, and a cleaning member for cleaning a light incident surface of the lens array. The photoconductor drum has a surface layer containing inorganic particles. The cleaning member has a drum rubbing part that has a rubbing surface rubbing the surface of the photoconductor drum. The rubbing surface rubbing the surface of the photoconductor drum is formed of a fiber having an average fiber diameter of 20 μm or more and 100 μm or less.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to an image forming apparatus using a photosensitive drum. [Background technology]

[0002] In electrophotographic image forming devices such as laser beam printers and digital copiers, one method of exposing a photosensitive drum is to use an exposure head in which multiple light-emitting elements such as LEDs or organic ELs are arranged in a substantially linear fashion in a direction parallel to the rotation axis of the photosensitive drum (the main scanning direction), and the photosensitive drum is exposed all at once in the main scanning direction. This method is smaller in volume and does not require a drive unit than laser scanning exposure devices that use a polygon mirror for scanning, making it advantageous for making image forming devices more compact and quieter.

[0003] A solid-state exposure head includes a lens array consisting of multiple gradient index lenses arranged in the main scanning direction facing the light-emitting element to focus the light beam emitted from the light-emitting element onto the photosensitive drum. Because the focal length of this lens array is extremely short, the solid-state exposure head must be placed very close to the photosensitive drum. However, toner may be floating near the photosensitive drum, carried by the airflow used to cool the inside of the image forming device. If this floating toner adheres to the light-emitting surface of the lens array, the amount of light irradiating the photosensitive drum becomes uneven, resulting in defective images with uneven density and other problems. For this reason, a cleaning means is required to clean the surface of the lens array in solid-state exposure heads.

[0004] As an example of a cleaning means, Patent Document 1 discloses a means for cleaning a lens array by providing a guide unit that controls the distance between the photosensitive drum and the cleaning member. However, in an image forming apparatus in which the packaging density of internal units is increased in an effort to reduce size, it may be difficult to provide such a guide unit near the solid-state exposure head.

[0005] As a method for responding to the need for such miniaturization of the internal unit, Patent Document 2 discloses a means for cleaning the surface of the lens array by providing a drum rubbing portion for an electrophotographic photosensitive drum on the surface of the cleaning member facing the photosensitive drum, and bringing the drum rubbing portion into contact with the photosensitive drum. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Patent No. 4848709 [Patent Document 2] Patent No. 4743303 Summary of the Invention [Problem to be solved by the invention]

[0007] However, the configuration described in Patent Document 2, in which the lens array is cleaned while the drum sliding portion is in contact with the lens array, has the following problem. That is, if inorganic fine particles are contained on the outermost surface of the photosensitive drum that is in contact with the lens array, the inorganic fine particles will detach. This changes the surface characteristics of the photosensitive drum, causing uneven exposure when the photosensitive drum is irradiated with light from an LED exposure head, resulting in image defects such as uneven density. The present disclosure aims to provide an image forming apparatus that suppresses image defects caused by uneven exposure, even when the apparatus has a photosensitive drum that contains inorganic fine particles on its surface. [Means for solving the problem]

[0008] The image forming apparatus of the present disclosure includes: a photosensitive drum rotatable around a rotation axis; a plurality of light-emitting elements for emitting exposure light to be irradiated onto the surface of the photosensitive drum; a lens array having a light incident surface facing the light emitting elements and a light exit surface facing the photosensitive drum, the lens array being configured so that a plurality of lenses are arranged in the direction of the rotation axis to focus the exposure light emitted from the light emitting elements onto the surface of the photosensitive drum; a cleaning member that is inserted between the surface of the photosensitive drum and the light exit surface of the lens array, and that cleans the light exit surface of the lens array while rubbing the surface of the photosensitive drum and the light exit surface of the lens array from one end side to the other end side in the longitudinal direction of the lens array; An image forming apparatus having: the photosensitive drum has a surface layer containing inorganic particles, the cleaning member has a drum rubbing portion having a rubbing surface that rubs against the surface of the photosensitive drum, The sliding surface that slides against the surface of the photosensitive drum is characterized by being made of fibers with an average fiber diameter of 20 μm or more and 100 μm or less. [Effects of the Invention]

[0009] According to the present disclosure, in a configuration in which a guide member for contacting a cleaning member with the lens array surface is sandwiched between the lens array and the photosensitive drum, and the lens array is cleaned while the photosensitive drum and the drum sliding portion for the photosensitive drum are in contact, it is possible to prevent the inorganic particles added to the photosensitive drum surface from detaching during the cleaning operation. [Brief explanation of the drawings]

[0010] [Figure 1A] FIG. 1 is a diagram illustrating an example of an electrophotographic apparatus used in the present disclosure. [Figure 1B] FIG. 2 is an enlarged view of the photosensitive drum and its surroundings in the electrophotographic apparatus used in the present disclosure. [Figure 2] FIG. 1 is a diagram illustrating an example of an exposure apparatus used in the present disclosure. [Figure 3] 1A and 1B are diagrams illustrating an example of a cleaning member used in the present disclosure. [Figure 4] FIG. 10 is a diagram showing an example of a cleaning form of the exposure apparatus used in the present disclosure. [Figure 5] FIG. 2 is a diagram illustrating an example of a photosensitive drum used in the present disclosure. [Figure 6] FIG. 1 is a diagram showing an apparatus for polishing a cylindrical electrophotographic photosensitive member using an abrasive sheet. DETAILED DESCRIPTION OF THE INVENTION

[0011] The present disclosure will be described in detail below by way of preferred embodiments. [Electrophotographic equipment] FIG. 1A shows an example of the schematic configuration of an electrophotographic apparatus having a process cartridge. The electrophotographic device 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 about rotation axes 10Y, 10M, 10C, and 10K, respectively. The rotation axes are perpendicular to the plane of the drawing at rotation axes 10Y, 10M, 10C, and 10K, and the rotation axis direction refers to the direction perpendicular to the plane of the drawing.

[0012] Around the photosensitive drums, there are provided chargers 104Y, 104M, 104C, and 104K, solid-state (LED) exposure heads 105Y, 105M, 105C, and 105K, developers 106Y, 106M, 106C, and 106K, and drum cleaning members 108, which correspond to the respective toners, 108Y, 108M, 108C, and 108K.

[0013] FIG. 1B shows an example of the schematic configuration of a process cartridge equipped with a photosensitive drum according to the present disclosure. The photosensitive drum 103 is rotatable about a rotation axis 10, i.e., rotates around the rotation axis 10. The rotation axis is a line perpendicular to the plane of the paper on which this drawing is drawn on the rotation axis 10, and the direction of the rotation axis refers to the direction perpendicular to the plane of the paper on which this drawing is drawn. After the toner image is transferred, the surface of the photosensitive drum 103 is cleaned by removing the remaining developer (residual toner) using a drum cleaning member (e.g., a blade) 108. When each term corresponds to a toner of each color, Y, M, C, or K is added to the end, but when there is no need to distinguish between them, these may be omitted.

[0014] <Image formation process> The photosensitive drums 103Y, 103M, 103C, and 103K, which are uniformly charged by the chargers 104Y, 104M, 104C, and 104K, are exposed by the LED exposure heads 105Y, 105M, 105C, and 105K to form 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 transferred to the intermediate transfer belt 107 at the primary transfer sections Ty, Tm, Tc, and Tk.

[0015] 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 conveyed from a paper feed section 101. The recording sheet P onto which the toner images have been transferred is conveyed 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.

[0016] <Solid-state exposure equipment> FIG. 3 shows a cross-sectional view of a solid-state exposure head 201 as an example. A light-emitting substrate 202, on which LED chips serving as multiple light-emitting elements 203 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 zinc-plated 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 103 using the light beams emitted from the light-emitting elements 203. At this time, the distance from the LED 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 103 are approximately equal. The distance between the light emitting element 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 by adhesive to the housing 205. In this embodiment, an LED 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.

[0017] <Cleaning mechanism> As mentioned above, if toner or other foreign matter adheres to the light-emitting surface of the lens array 206, it will partially block the light emitted from the light-emitting elements, resulting in a deterioration in the quality of the output image. Therefore, the light-emitting surface of the lens array 206 needs to be cleaned periodically.

[0018] The lens array cleaning member 300 (also referred to as cleaning member 300) is inserted between the surface of the photosensitive drum 103 and the light exit surface of the lens array 206. The cleaning member 300 cleans the light exit surface of the lens array 206 while rubbing the surface of the photosensitive drum 103 and the light exit surface of the lens array 206 from one end side to the other end side in the longitudinal direction of the lens array 206.

[0019] 3 shows an example of an overall view of the cleaning member 300 of the solid-state exposure head 105 used in the present disclosure. The cleaning member 300 is generally elongated and rod-shaped, and includes a rod-shaped body portion 303, a grip portion 302 at one end, and a cleaning portion 301 at the other end. The cleaning portion 301 includes a body end portion 303a that is part of the body portion 303, a lens array sliding portion 401, and a drum sliding portion 402. The body 303 is made of engineering plastic such as ABS or PP.

[0020] <Lens array sliding part and drum sliding part> FIG. 4 shows a state in which the lens array rubbing portion 401 of the cleaning member 300 is in contact with the lens array 206 to perform cleaning.

[0021] The cleaning unit 301 includes a lens array rubbing unit 401 on the surface facing the lens array 206, and a drum rubbing unit 402 having a rubbing surface facing the photosensitive drum 103 side.

[0022] The lens array rubbing unit 401 wipes the lens array emission surface with the tip of a blade made of a material such as urethane rubber to remove foreign matter. Other materials such as silicone rubber or chloroprene rubber may also be used. It is also possible to consider a configuration in which nonwoven fabric or felt is selected instead of a blade for cleaning. Felt refers to a state in which fibers are entangled and shrunk, and the fibers may be natural fibers, synthetic fibers, or a mixture of these.

[0023] The sliding surface of the drum sliding portion 402 is formed in at least one shape selected from the group consisting of woven fabric, felt, nonwoven fabric, and brush. Specific preferred materials for forming the woven fabric, felt, nonwoven fabric, and brush include natural fibers such as animal fibers like wool, alpaca, angora, cashmere, goat, camel, mohair, and silk, and natural fibers such as plant fibers like cotton and hemp, as well as synthetic fibers such as acrylic, polyester, nylon, polyurethane, rayon, acetate, and triacetate.

[0024] In particular, when the sliding surface is in the form of felt, nonwoven fabric or brush, materials made of nylon (polyamide), rayon, polyester and polyurethane are preferred, among which polyester and polyurethane are preferred.

[0025] The woven fabric, felt, nonwoven fabric, and brush used in the drum sliding portion 402 are made of fibers with an average fiber diameter of 20 μm or more and 100 μm or less. In the examples of the present disclosure, the average fiber diameter was measured using a Keyence VHX-6600 at a magnification of 50x, avoiding 10 μm from the fiber tip, and the arithmetic average of 100 fibers was taken as the average fiber diameter.

[0026] The tensile strength is preferably 20 cN / dtex or more and 50 cN / dtex or less, more preferably 20 to 40 cN / dtex. The tensile strength was measured in accordance with JIS-L-1015 using an Instron Model 5565 under the following conditions:

[0027] Grip spacing: 20mm Initial load: 0.044cN(1 / 20g) / dtex Pulling speed: 20 mm / min For the drum sliding portion, only one type may be used, or two or more types may be used as a mixture or copolymer.

[0028] [Photosensitive drum] 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. 5. In Fig. 5, 501 is a support, 502 is an undercoat layer, 503 is a charge generation layer, 504 is a charge transport layer, and 505 is a protective layer.

[0029] <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.

[0030] The shape is preferably cylindrical. The surface of the support may be subjected to electrochemical treatment such as anodization, blasting, cutting, or the like.

[0031] The shape of the support may be, for example, cylindrical or film-like. Among these, a cylindrical aluminum support is superior 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 treatment such as cutting, honing, or blasting, or to chemical treatment using an acid or the like, in order to improve electrical properties or suppress interference fringes, and then the resulting support may be used.

[0032] <Conductive layer> The conductive layer is a layer that may be provided if necessary. 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. 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. The conductive layer contains conductive particles and a resin.

[0033] Examples of the material of the conductive particles include metal oxides, metals, and carbon black. Examples of metal oxides include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, strontium titanate, magnesium oxide, antimony oxide, and bismuth oxide. Among these, metals include aluminum, nickel, iron, nichrome, copper, zinc, and silver. Of the above materials for the conductive particles, metal oxides are preferred, and titanium oxide, tin oxide, and zinc oxide are particularly preferred. 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. 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. The coating layer and the surface treated with the silane coupling agent are much thicker than each other. 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.

[0034] 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. Furthermore, the conductive layer may contain silicone oil, resin particles, a masking agent such as titanium oxide, and the like.

[0035] 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. 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. 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. 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.

[0036] <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.

[0037] 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.

[0038] 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.

[0039] 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. 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. 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.

[0040] The metal oxide contained in the undercoat layer may be surface-treated with a surface treatment agent such as a silane coupling agent. The metal oxide surface treatment can be carried out by a common method, such as a dry method or a wet method. 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 metal oxide, followed by drying. 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.

[0041] 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. 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. 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. 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. 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.

[0042] <Charge generation layer> Directly over the undercoat layer is a charge generating layer. Examples of the charge generating material include perylene pigments, anthraquinone derivatives, anthanthrone derivatives, dibenzpyrenequinone derivatives, pyranthrone derivatives, violanthrone derivatives, isoviolanthrone derivatives, indigo derivatives, thioindigo derivatives, phthalocyanine pigments such as metal phthalocyanines and metal-free phthalocyanines, and bisbenzimidazole derivatives. Among these, phthalocyanine pigments are preferred. Among phthalocyanine pigments, oxytitanium phthalocyanine, chlorogallium phthalocyanine, and hydroxygallium phthalocyanine are preferred.

[0043] 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°.

[0044] 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 28.2° 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°.

[0045] 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°.

[0046] 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.

[0047] 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. The thickness of the charge generating layer is preferably 0.05 μm or more and 5 μm or less.

[0048] <Charge transport layer> The charge transport layer can be obtained by dissolving or dispersing a charge transport material 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.

[0049] Examples of charge transport materials 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, triarylamine compounds, styryl compounds, and benzidine compounds are preferred as charge transport materials, with triarylamine compounds being particularly preferred. The charge transport materials can be used singly or in combination of one or more.

[0050] 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.

[0051] The content of the charge transport material in the charge transport layer is preferably 20% by mass to 80% by mass, more preferably 30% by mass to 60% by mass, based on the total mass of the charge transport layer.

[0052] In the present disclosure, when the charge transport layer is the outermost layer, inorganic particles are added from the viewpoint of abrasion resistance. The inorganic particles to be added are selected from alumina, silicon dioxide, oxide, etc. from the viewpoint of hardness and lubricity. Particles containing tin and indium tin oxide are preferred.

[0053] In the examples of the present disclosure, the average particle size and average circularity of inorganic particles contained in the surface layer of an electrophotographic photoreceptor were measured using a field emission scanning electron microscope (FE-SEM) as follows. The inorganic particles in the charge transport layer were measured by observing the cross section in the thickness direction. The cross-sectional observation sample was prepared by cutting the coated photoreceptor drum into 3 mm pieces using a cutting machine and polishing the measurement surface using an ion beam. A cross-section polisher, for example, can be used for polishing the cross section using an ion beam. Polishing the cross section using an ion beam can prevent filler particles from falling off the sample and abrasive contamination, and can also form a cross section with minimal polishing marks. Multiple measurement samples were prepared and observed using an FE-SEM (S-4700) manufactured by Hitachi High-Technologies Corporation. The FE-SEM measurement conditions are as follows: Accelerating voltage: 2 kV WD: 5mm Magnification: 20,000 times Number of pixels: 1280 pixels vertically, 960 pixels horizontally (size of each pixel: 5 nm) From the obtained images, the Feret's diameter of 500 particles was determined using ImageJ (open source software from the National Institutes of Health (NIH)), and the average value was calculated to obtain the average primary particle size.

[0054] Similarly, the area and circumference were determined, and the circularity was calculated from the following formula (I), and the average value was calculated to obtain the average circularity. Circularity = 4 × π × (area) ÷ (perimeter squared) Formula (I) The average particle size is preferably 0.1 to 4.0 μm, more preferably 0.5 to 2.0 μm. The thickness of the charge transport layer is preferably 5 μm or more and 40 μm or less.

[0055] <Protective layer> In the present disclosure, a protective layer may be provided on the photosensitive layer. By providing the protective layer, durability can be improved. When the protective layer is provided, the protective layer becomes the surface layer of the photosensitive drum.

[0056] The protective layer is 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 also be used as the monomer having the polymerizable functional group.

[0057] Among these, from the viewpoint of mechanical durability, the monomer having a polymerizable functional group is preferably a monomer having three or more polymerizable functional groups in the molecule (a monomer having a trifunctional or higher functional polymerizable functional group), and a UV-curable acrylic resin containing a trifunctional or higher radical polymerizable monomer is more preferred in terms of excellent abrasion resistance. Among these, trifunctional to hexafunctional polymerizable compounds are particularly preferred.

[0058] By polymerizing the trifunctional or higher polymerizable compound, a three-dimensional network structure develops, resulting in a protective layer with extremely high crosslinking density, high hardness, and high elasticity, which is advantageous in that it provides high abrasion resistance and scratch resistance.

[0059] Examples of monomers having three or more polymerizable functional groups include trimethylolpropane triacrylate (TMPTA), trimethylolpropane trimethacrylate, trimethylolpropane alkylene-modified triacrylate, trimethylolpropane ethyleneoxy-modified (EO-modified) triacrylate, trimethylolpropane propyleneoxy-modified (PO-modified) triacrylate, trimethylolpropane caprolactone-modified triacrylate, trimethylolpropane alkylene-modified trimethacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate (PETTA), glycerol triacrylate, glycerol epichlorohydrin-modified (ECH-modified) triacrylate, and glycerol Examples of the acrylates include ethylene glycol EO-modified triacrylate, glycerol PO-modified triacrylate, tris(acryloxyethyl)isocyanurate, dipentaerythritol hexaacrylate (DPHA), dipentaerythritol caprolactone-modified hexaacrylate, dipentaerythritol hydroxypentaacrylate, alkylated dipentaerythritol pentaacrylate, alkylated dipentaerythritol tetraacrylate, alkylated dipentaerythritol triacrylate, dimethylolpropane tetraacrylate (DTMPTA), pentaerythritol ethoxy tetraacrylate, EO-phosphate-modified triacrylate, and 2,2,5,5-tetrahydroxymethylcyclopentanone tetraacrylate. These may be used alone or in combination of two or more.

[0060] In addition, in the present disclosure, inorganic particles are added to the protective layer from the viewpoint of abrasion resistance. From the viewpoint of hardness and lubricity, the inorganic particles to be added are preferably particles containing alumina, silicon dioxide, tin oxide, or indium tin oxide.

[0061] The average particle size is preferably 0.1 to 4.0 μm, more preferably 0.5 to 2.0 μm. In the examples of the present disclosure, the average particle size and average circularity of the inorganic particles contained in the surface layer of the electrophotographic photoreceptor were calculated using the same method as for the particles added to the charge transport layer. The thickness of the protective layer is preferably 0.05 μm or more and 20 μm or less, and more preferably 0.5 μm or more and 5.0 μm or less.

[0062] 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 spray coating method and the dip coating method are preferred from the viewpoints of efficiency and productivity. [Example]

[0063] The present disclosure will be described in more detail below using examples and comparative examples, but is not limited thereto. In the following description of the examples, "parts" refers to parts by mass unless otherwise specified. However, the present disclosure is not limited thereto. 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 (Fischerscope, manufactured by Fisher Instruments), a method using a spectral interference film thickness meter (C-13027-11, manufactured by Hamamatsu Photonics), or a method converting the mass per unit area into specific gravity.

[0064] [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.

[0065] (Conductive 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.

[0066] 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. After the dispersion treatment, 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 conductive layer. The obtained conductive layer coating liquid 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 a conductive layer having a thickness of 18 μm.

[0067] (charge generation layer) 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 (E) 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 in a sand mill using 1 mm diameter glass beads in an atmosphere of 23±3°C for 1 hour, and after the dispersion process, 100 parts of ethyl acetate was added to prepare a coating solution for a charge generating layer. This charge generating layer coating liquid was dip coated onto the conductive 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. [ka]

[0068] (charge transport layer) A coating solution for a charge transport layer was prepared by dissolving 60 parts of a compound represented by the following formula (F), 30 parts of a compound represented by the following formula (G), 10 parts of a compound represented by the following formula (H), 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 (I) (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. 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. [ka] [ka] [ka] [ka] (In formula (I), 0.95 and 0.05 are the molar ratios (copolymerization ratios) of the two structural units.)

[0069] <Preparation of Coating Solution for Protective Layer> A 70 cc glass pot was charged with 5 mm diameter alumina balls, and then 8 mass% of aluminum oxide particles (Sumicorundum AA-03, average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical Co., Ltd.) and 8 mass% of cyclopentanone were added, followed by dispersion in a ball mill (150 rpm) for 400 hours. 12 mass% of tetrahydrofuran was then added and stirred to obtain a mill base. A coating solution for the protective layer was prepared by mixing 3% by mass of the obtained mill base with 4% by mass of TMPTA: trimethylolpropane triacrylate (a trifunctional radically polymerizable compound, manufactured by Tokyo Chemical Industry Co., Ltd.), 4% by mass of the following compound, 0.5% by mass of a photopolymerization initiator (1-hydroxycyclohexylphenyl ketone, Irgacure 184, manufactured by Ciba Specialty Chemicals), 0.01% by mass of a leveling agent (polyester-modified acrylic group-containing polydimethylsiloxane solution, BYK-UV3510, manufactured by BYK Chemie), and 50% by mass of tetrahydrofuran. [ka] This protective layer coating solution 1 was spray coated onto the charge transport layer, and the irradiation intensity of a metal halide lamp was 500 mW / cm 2 The coating was then irradiated with light for 20 seconds, and then dried at 130° C. for 30 minutes to form a protective layer having a thickness of 5.0 μm, thereby preparing an electrophotographic photoreceptor 1.

[0070] <Surface treatment of electrophotographic photoreceptors> (Polishing of electrophotographic photoreceptor before surface polishing) The surface of an electrophotographic photoreceptor prior to surface texture formation was polished. The polishing was performed using the polishing apparatus shown in Figure 6. Figure 6 shows an apparatus for polishing a cylindrical electrophotographic photoreceptor using an abrasive sheet. In Figure 6, an abrasive sheet 6-1 is wound around a hollow shaft 6-6, and a motor (not shown) is arranged to apply tension to the abrasive sheet 6-1 in the direction opposite to the direction in which the abrasive sheet 6-1 is fed around the shaft 6-6. The abrasive sheet 6-1 is fed in the direction indicated by the arrow, passing through guide rollers 6-2a and 6-2b and a backup roller 6-3. After polishing, the abrasive sheet 6-1 is wound around a winding means 6-5 by the motor (not shown) via guide rollers 6-2c and 6-2d. Polishing is performed by constantly pressing the abrasive sheet 6-1 against the workpiece (electrophotographic photoreceptor prior to polishing) 6-4. Because the abrasive sheet 6-1 is often insulating, it is preferable to use a grounded or conductive material for the area in contact with the abrasive sheet 6-1. Abrasive sheet feed speed: 400mm / min The polishing was carried out under the following conditions: Electrophotographic photoreceptor rotation speed: 450 rpm Pressing of electrophotographic photoreceptor into backup roller: 3.5 mm Rotation direction of the abrasive sheet and electrophotographic photoreceptor; Backup roller; outer diameter 100 mm, Asker C hardness 25 GC3000 (abrasive sheet surface roughness Ra0.83μm) The polishing time was 10 seconds.

[0071] (Measurement of polishing roughness Rmax (μm)) After polishing, the maximum height Rmax of the electrophotographic photosensitive member was measured using a surface roughness measuring instrument, Surfcorder SE3500, manufactured by Kosaka Laboratory Co., Ltd., in accordance with JIS B 0601 1982. The measurement conditions were set as follows: (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

[0072] <Lens array sliding part and drum sliding part> Lens array rubbing portion 401 is a blade made of urethane rubber, and drum rubbing portion 402 uses felt-shaped wool with an average fiber diameter of 20 μm and a tensile strength of 20 cN / dtex.

[0073] [Example 2] A photosensitive drum 2 was obtained in the same manner as in Example 1 except for the drum sliding portion 402, except that the protective layer coating liquid was changed as follows:

[0074] (Protective layer coating solution 2) A dispersant solution was prepared by dissolving 2.8 parts of a graft copolymer having structures represented by the following formulas (A1) and (A2) in a mixed solvent consisting of 100 parts of 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (trade name: AE-3000, manufactured by AGC Corporation) and 100 parts of 1-propanol. To the resulting dispersant solution, 8% by mass of aluminum oxide particles (Sumicorundum AA-03, average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical Co., Ltd.) was added, and the mixture was passed through a high-pressure disperser (trade name: Microfluidizer M-110EH, manufactured by Microfluidics, Inc., USA) to obtain an aluminum oxide particle dispersion. To the obtained aluminum oxide particle dispersion, 75.4 parts of a hole transport compound represented by the following formula (B), 21.9 parts of a compound represented by the following formula (C), and 100 parts of 1-propanol were added, followed by filtration using a Polyflon filter (trade name: PF-040, manufactured by Advantec Toyo Co., Ltd.) to prepare an aluminum oxide particle dispersion (coating liquid for protective layer). [ka] [ka] [ka] 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, in a nitrogen atmosphere, the coating film was heat-treated for 15 seconds under conditions where the temperature of the coating film reached 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 until the temperature reached 25°C, and then heat-treated for 1 hour under conditions where the temperature of the coating film reached 105°C, forming a surface layer (protective layer) with a thickness of 5 μm. In this way, a photosensitive drum 1 having a support and a surface layer before surface polishing was produced.

[0075] <Drum sliding part> For the drum sliding portion 402, a polypropylene brush having an average fiber diameter of 100 μm and a tensile strength of 20 cN / dtex was used.

[0076] [Example 3] In Example 1, a nonwoven fabric of alpaca having an average fiber diameter of 25 μm and a tensile strength of 40 cN / dtex was used for the drum sliding portion 402. The other configurations were the same as those of Example 1.

[0077] [Example 4] In Example 1, a polyester nonwoven fabric having an average fiber diameter of 30 μm and a tensile strength of 50 cN / dtex was used for the drum sliding portion 402. The other configurations were the same as those of Example 1.

[0078] [Example 5] In Example 1, a polyurethane nonwoven fabric having an average fiber diameter of 50 μm and a tensile strength of 20 cN / dtex was used for the drum sliding portion 402. The other configurations were the same as in Example 1.

[0079] [Example 6] In Example 1, a nylon nonwoven fabric having an average fiber diameter of 20 μm and a tensile strength of 45 cN / dtex was used for the drum sliding portion 402. The other configurations were the same as in Example 1.

[0080] [Example 7] A photosensitive drum was produced in the same manner as in Example 1, except that the aluminum oxide particles (Sumicorundum AA-03, average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical Co., Ltd.) in the mill base were replaced with ITO (indium tin oxide) particles (ITO TC8 DE X, average primary particle size: 0.2 μm, manufactured by Evonik Industries AG).

[0081] [Example 8] A photosensitive drum was prepared in the same manner as in Example 1, except that the aluminum oxide particles (Sumicorundum AA-03, average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical Co., Ltd.) in the mill base were replaced with tin oxide particles (NanoTek Powder SnO2, average primary particle size: 0.2 μm, manufactured by CIK NanoTek Co., Ltd.).

[0082] [Example 9] A photosensitive drum was prepared in the same manner as in Example 1, except that the aluminum oxide particles (Sumicorundum AA-03, average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical Co., Ltd.) in the mill base were replaced with silica particles (KMPX-100, average primary particle size: 0.1 μm, manufactured by Shin-Etsu Chemical Co., Ltd.).

[0083] [Example 10] A photosensitive drum was prepared in the same manner as in Example 1, except that the aluminum oxide particles (Sumicorundum AA-03, average primary particle size: 0.3 μm, manufactured by Sumitomo Chemical Co., Ltd.) in the mill base were replaced with silicone particles (Tospearl 120, average primary particle size: 2 μm, manufactured by Shin-Etsu Chemical Co., Ltd.).

[0084] [Example 11] Photosensitive drum 3 was obtained in the same manner as in Example 1, except that no protective layer was provided, the outermost layer was a charge transport layer, no surface processing treatment was performed, and the charge transport layer was changed as follows.

[0085] <Charge transport layer> A coating solution for a charge transport layer was prepared by dissolving 60 parts of the compound represented by formula (F), 30 parts of the compound represented by formula (G), 10 parts of the compound represented by formula (H), 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 formula (I) (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. 10 parts by mass of silicone particles (Tospearl 120, average primary particle size: 2 μm, manufactured by Shin-Etsu Chemical Co., Ltd.) were added to the coating liquid for the charge transport layer, and the mixture was passed through a high-pressure disperser (product name: Microfluidizer M-110EH, manufactured by Microfluidics, Inc., USA) to obtain a coating liquid for the charge transport layer with dispersed silicone particles.

[0086] [Comparative Example 1] In Example 1, a nylon nonwoven fabric having an average fiber diameter of 15 μm and a tensile strength of 52 cN / dtex was used for the drum sliding portion 402. The other configurations were the same as those of Example 1.

[0087] Comparative Example 2 In Example 1, a nonwoven fabric of alpaca having an average fiber diameter of 15 μm and a tensile strength of 50 cN / dtex was used for the drum sliding portion 402. The other configurations were the same as those of Example 1.

[0088] Comparative Example 3 In Example 1, a nylon nonwoven fabric having an average fiber diameter of 110 μm and a tensile strength of 56 cN / dtex was used for the drum sliding portion 402. The other configurations were the same as those of Example 1.

[0089] [evaluation] The drum sliding portion where the electrophotographic photosensitive member obtained in Examples 1 to 11 and Comparative Examples 1 to 3 was slid against the lens array was evaluated as follows. (Evaluation unit) The evaluation was carried out using an evaluation machine that was a Canon Inc. multifunction printer imageRUNNER ADVANCE C5870F with the following modifications. The evaluation was carried out using a modified machine in which the LED exposure mechanism mentioned in the example above was installed in the area where the exposure section had been removed. The above evaluation device was placed in a normal temperature and humidity environment of a temperature of 23°C and a relative humidity of 50%RH, and the prepared electrophotographic photosensitive member was attached to a cyan color process cartridge, which was then attached to the station of the cyan process cartridge, and evaluation was performed.

[0090] (Uneven exposure image evaluation) The uneven exposure image evaluation was carried out using the above evaluation machine. After printing 50 sheets, the lens array was wiped 10 times while rubbing the photosensitive drum with a cleaning member for the lens array. Then, a halftone image was output so that the cyan value was 0.5 in density measurement using an X-Rite (manufactured by X-Rite Corporation), and the level of unevenness in the image density was evaluated. A: No unevenness in shade B: Slight unevenness in shade C: There is unevenness in the shade

[0091] (Drum scratch evaluation) The photosensitive drum used for the uneven exposure image was removed from the evaluation machine, and the length of scratches on the surface of the photosensitive drum that had come into contact with the drum sliding portion 402 was observed under a microscope. The evaluation criteria are as follows: A: There are no scratches, or if there are any, they are minor. B: There is a scratch of about 1000 μm, but it does not affect the output image. C: Scratches reach 1000 μm or more, affecting the output image.

[0092] (fiber fuzz evaluation) The photosensitive drum used for the uneven exposure image was removed from the evaluation machine, and fiber fluffs on the surface of the photosensitive drum that the drum sliding portion 402 abutted against were checked. 〇: No fuzz ×: There is fuzz

[0093] (Evaluation of particle detachment) The drum used for evaluating fiber fuzz was removed and the detached particles were observed under a microscope. The area where the drum had come into contact was cut out to 3 mm x 3 mm. The cut sample was observed using a Hitachi High-Technologies FE-SEM (S-4700). The measurement conditions for the FE-SEM were as follows: Accelerating voltage: 2 kV WD:15mm Magnification: 10,000 times From the observed SEM images, 50 μm × 50 μm images were created, and the number of actual particles observed on the surface and the ratio of detachment marks were calculated.

[0094] Table 1 shows the types of inorganic particles in the outermost layer and in the surface layer of the photosensitive drums of Examples 1 to 11 and Comparative Examples 1 to 3, the average particle size, tensile strength, and the evaluation results of unevenness in density, drum scratches, fiber fluff, and particle detachment rate.

[0095] [Table 1]

[0096] Embodiments of the present disclosure include the following configurations. (Configuration 1) a photosensitive drum rotatable around a rotation axis; a plurality of light-emitting elements for emitting exposure light to be irradiated onto the surface of the photosensitive drum; a lens array having a light incident surface facing the light emitting elements and a light exit surface facing the photosensitive drum, the lens array being configured by arranging a plurality of lenses in the rotation axis direction to focus the exposure light emitted from the light emitting elements onto the surface of the photosensitive drum; a cleaning member that is inserted between the surface of the photosensitive drum and the light exit surface of the lens array, and that cleans the light exit surface of the lens array while rubbing the surface of the photosensitive drum and the light exit surface of the lens array from one end side to the other end side in the longitudinal direction of the lens array; An image forming apparatus having: the photosensitive drum has a surface layer containing inorganic particles, the cleaning member has a drum rubbing portion having a rubbing surface that rubs against the surface of the photosensitive drum, An image forming apparatus, wherein the sliding surface that slides against the surface of the photosensitive drum is made of fibers having an average fiber diameter of 20 μm or more and 100 μm or less. (Configuration 2) 2. The image forming apparatus according to claim 1, wherein the sliding surface is made of felt formed from the fibers. (Configuration 3) 3. The image forming apparatus according to claim 1, wherein the sliding surface is made of a nonwoven fabric formed from the fibers. (Configuration 4) 4. The image forming apparatus according to any one of configurations 1 to 3, wherein the tensile strength of the fiber is 20 cN / dtex or more and 50 cN / dtex or less. (Configuration 5) 5. The image forming apparatus according to any one of configurations 1 to 4, wherein the fibers contain polyurethane. (Configuration 6) 6. The image forming apparatus according to any one of configurations 1 to 5, wherein the inorganic particles are particles containing silicon dioxide. (Configuration 7) 7. The image forming apparatus according to any one of configurations 1 to 6, wherein the inorganic particles are particles containing tin oxide. (Configuration 8) 8. The image forming apparatus according to any one of configurations 1 to 7, wherein the inorganic particles are particles containing indium tin oxide. (Configuration 9) 9. The image forming apparatus according to any one of configurations 1 to 8, wherein the tensile strength of the fibers is 20 cN / dtex or more and 50 cN / dtex or less. [Explanation of symbols]

[0097] 103 Photosensitive drum 105 LED exposure head 108 Drum cleaning material 206 Lens Array 300 Lens array cleaning material 301 Cleaning Department 401 Photosensitive drum sliding part

Claims

1. a photosensitive drum rotatable around a rotation axis; a plurality of light-emitting elements for emitting exposure light to be irradiated onto the surface of the photosensitive drum; a lens array having a light incident surface facing the light emitting elements and a light exit surface facing the photosensitive drum, the lens array being configured by arranging a plurality of lenses in the rotation axis direction to focus the exposure light emitted from the light emitting elements onto the surface of the photosensitive drum; a cleaning member that is inserted between the surface of the photosensitive drum and the light exit surface of the lens array, and that cleans the light exit surface of the lens array while rubbing the surface of the photosensitive drum and the light exit surface of the lens array from one end side to the other end side in the longitudinal direction of the lens array; An image forming apparatus having: the photosensitive drum has a surface layer containing inorganic particles, the cleaning member has a drum rubbing portion having a rubbing surface that rubs against the surface of the photosensitive drum, the sliding surface that slides against the surface of the photosensitive drum is made of fibers having an average fiber diameter of 20 μm or more and 100 μm or less; An image forming apparatus characterized by:

2. 2. The image forming apparatus according to claim 1, wherein the sliding surface is made of felt formed from the fibers.

3. 2. The image forming apparatus according to claim 1, wherein the sliding surface is made of a nonwoven fabric formed from the fibers.

4. 4. The image forming apparatus according to claim 1, wherein the tensile strength of the fiber is 20 cN / dtex or more and 50 cN / dtex or less.

5. 4. The image forming apparatus according to claim 1, wherein the fibers contain polyester.

6. 4. The image forming apparatus according to claim 1, wherein the fibers contain polyurethane.

7. 4. The image forming apparatus according to claim 1, wherein the inorganic particles are particles containing silicon dioxide.

8. 4. The image forming apparatus according to claim 1, wherein the inorganic particles are particles containing tin oxide.

9. 4. The image forming apparatus according to claim 1, wherein the inorganic particles are particles containing indium tin oxide.

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