Image forming apparatus

Abstract

To provide an image forming apparatus that prevents dust from attaching to a surface of a photoconductor drum during a cleaning operation.SOLUTION: An image forming apparatus has: a photoconductor drum that is rotatable about a rotation axis; a plurality of light-emitting devices for emitting exposure light with which a surface of the photoconductor drum is irradiated; a lens array in which a plurality of lenses for condensing the exposure light emitted from the light-emitting devices on the surface of the photoconductor drum are arranged in a direction of the rotation axis, and has a light incident surface facing the light-emitting devices and a light emission surface facing the photoconductor drum; and a cleaning member that is inserted between the surface of the photoconductor drum and the light emission surface of the lens array, for cleaning the light emission surface of the lens array, while rubbing the surface of the photoconductor drum and the light emission surface of the lens array, from one end side up to the other end side in a longitudinal direction of the lens array. The photoconductor drum contains a specific bisazo compound as a charge generating material contained in a photosensitive layer.SELECTED DRAWING: Figure 4

Description

Technical Field

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

Background Art

[0002] In an electrophotographic image forming apparatus such as a laser beam printer or a digital copying machine, there is a solid-state exposure head as one means for exposing a photosensitive drum. The solid-state exposure head arranges a plurality of light emitting points such as LEDs or organic ELs, which are light emitting elements, substantially linearly in a direction parallel to the rotation axis of the photosensitive drum (main scanning direction), and exposes the photosensitive drum all at once in the main scanning direction. This method is advantageous for miniaturization and low noise of the image forming apparatus because it has a smaller volume and no driving unit compared to an exposure apparatus of a laser scanning method that performs scanning using a polygon mirror.

[0003] The solid-state exposure head includes a lens array in which a plurality of refractive index distribution type lenses are arranged in the main scanning direction facing the light emitting element in order to form an image of the light beam emitted from the light emitting element on the photosensitive drum. Since the focal length of this lens array is extremely short, it is necessary to arrange the solid-state exposure head very close to the photosensitive drum. However, in the vicinity of the photosensitive drum, toner or the like may float on the air flow for internal cooling of the image forming apparatus. When such floating toner or the like adheres to the emission surface of the lens array, the amount of light irradiating the photosensitive drum becomes non-uniform, and defective images such as density unevenness occur. For this reason, the solid-state exposure head requires a cleaning means for cleaning the surface of the lens array.

[0004] As an example of the cleaning means, as shown in Patent Document 1, there is known a means for cleaning the lens array in a form in which a guide portion for controlling the distance between the photosensitive drum and the cleaning member is provided to guide. However, in an image forming apparatus in which the mounting density of internal units is increased for the purpose of miniaturization, it may be difficult to provide such a guide portion in the vicinity of the solid-state exposure head.

[0005] As a method for meeting the miniaturization of internal units, Patent Document 2 discloses a means for cleaning the surface of a lens array by providing a drum rubbing portion for an electrophotographic photosensitive drum on the surface of a cleaning member facing the photosensitive drum, while bringing the drum rubbing portion into contact with the photosensitive drum.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0007] However, in the case of a configuration in which the cleaning member is brought into contact with the surface of the lens array, sandwiched between the lens array and the photosensitive drum, and the lens array is cleaned while being brought into contact with the photosensitive drum, the following problems have existed. When animal fibers such as wool are selected as the member (drum rubbing portion) that comes into contact with the photosensitive drum, there has been a problem of attracting toner, dust, and dirt remaining in the machine to the surface of the photosensitive drum due to the electrostatic action between the drum rubbing portion and the photosensitive drum during the cleaning operation, thereby inhibiting image formation.

[0008] An object of the present disclosure is to suppress the adhesion of dust, dirt, etc. to the surface of the photosensitive drum during the operation of the cleaning member in an image forming apparatus that sandwiches the cleaning member between the photosensitive drum and cleans the lens array while bringing it into contact with the photosensitive drum in order to bring the cleaning member into contact with the surface of the lens array.

Means for Solving the Problems

[0009] The above object is achieved by the following present disclosure. That is, a photosensitive drum rotatable about a rotation axis, a plurality of light emitting elements for emitting exposure light irradiated onto the surface of the photosensitive drum, A lens array having a light incident surface facing the light emitting element and a light emitting surface facing the photosensitive drum, in which a plurality of lenses for condensing the exposure light emitted from the light emitting element are arranged in the direction of the rotation axis. A cleaning member inserted between the surface of the photosensitive drum and the light emitting surface of the lens array, and cleaning the light emitting surface of the lens array while rubbing the surface of the photosensitive drum and the light emitting 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 cleaning member has a drum rubbing portion that rubs against the surface of the photosensitive drum. The image forming apparatus, wherein the photosensitive drum has a photosensitive layer containing an azo compound represented by the following formula (1).

Chemical formula

Advantages of the Invention

[0010] According to the present disclosure, in an image forming apparatus that contacts a cleaning member against the surface of a lens array, sandwiches it between the lens array and a photosensitive drum, and cleans the lens array by bringing the photosensitive drum into contact with a drum rubbing portion, the following effects can be obtained. That is, during the operation of the cleaning member, adhesion of dust, dirt, etc. to the surface of the photosensitive drum can be suppressed.

Brief Description of the Drawings

[0011]

Figure 1-1

Figure 1-2

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0012] The image forming apparatus in the present disclosure includes a photosensitive drum rotatable about a rotation axis, a plurality of light emitting elements for emitting exposure light irradiated on the surface of the photosensitive drum, and a plurality of lenses for condensing the exposure light emitted from the light emitting elements on the surface of the photosensitive drum, arranged in the direction of the rotation axis. A lens array having a light incident surface facing the light emitting elements and a light emitting surface facing the photosensitive drum, and inserted between the surface of the photosensitive drum and the light emitting surface of the lens array, and wiping the surface of the photosensitive drum and the light emitting surface of the lens array from one end side to the other end side in the longitudinal direction of the lens array. A cleaning member for cleaning the light emitting surface of the lens array, and the cleaning member has a drum rubbing portion that rubs against the surface of the photosensitive drum, and the photosensitive drum has a photosensitive layer containing an azo compound represented by the following formula (1).

Chemical formula

[0013] Hereinafter, the present disclosure will be described in detail with reference to preferred embodiments. [Image Forming Apparatus] The image forming apparatus shown in Fig. 1-1 includes four image forming units 102Y, 102M, 102C, and 102K that form toner images of respective colors such as yellow, magenta, cyan, and black. The image forming units 102Y, 102M, 102C, and 102K each include a photosensitive drum 103Y, 103M, 103C, and 103K. In this specification, a cylindrical or columnar electrophotographic photoreceptor may be referred to as a photosensitive drum. Around the photosensitive drum 103, chargers 104Y, 104M, 104C, and 104K, solid-state exposure heads 201Y, 201M, 201C, and 201K, and developing devices 106Y, 106M, 106C, and 106K are provided. Hereinafter, when there is no need to distinguish, the photosensitive drums 103Y, 103M, 103C, and 103K may be collectively referred to as the photosensitive drum 103, and the chargers 104Y, 104M, 104C, and 104K may be collectively referred to as the charger 104.

[0014] [Image Forming Process] The photosensitive drums 103Y, 103M, 103C, and 103K uniformly charged by the chargers 104Y, 104M, 104C, and 104K are exposed by the solid-state exposure heads 201Y, 201M, 201C, and 201K to form an electrostatic latent image. Hereinafter, when there is no need to distinguish, the solid-state exposure heads 201Y, 201M, 201C, and 201K may be collectively referred to as the solid-state exposure head 201. The electrostatic latent image is visualized as a toner image of each color by the developing devices 106Y, 106M, 106C, and 106K. Then, it is transferred to the intermediate transfer belt 107 by the primary transfer rollers 108Y, 108M, 108C, and 108K in the primary transfer units T1y, T1m, T1c, and T1k. Hereinafter, when there is no need to distinguish, the developing devices 106Y, 106M, 106C, and 106K may be collectively referred to as the developing device 106, the primary transfer units T1y, T1m, T1c, and T1k may be collectively referred to as the primary transfer unit T1, and similarly, the primary transfer rollers 108Y, 108M, 108C, and 108K may be collectively referred to as the primary transfer roller 108. The toner images of various colors superimposed on the intermediate transfer belt 107 are collectively transferred by the secondary transfer roller 109 onto the recording paper P conveyed from the paper feeding unit 101 in the secondary transfer unit T2. The recording paper P onto which the toner image has been transferred is conveyed to the fixing unit 110, the toner image is fixed by heat and pressure, and then discharged from the paper discharging unit 111. The surface of the photosensitive drum 103 after transferring the toner image is cleaned by the drum cleaning members (such as blades) 112Y, 112M, 112C, 112K to remove the remaining developer (residual transfer toner) and made into a clean surface. The drum cleaning members 112Y, 112M, 112C, 112K may be collectively referred to as the drum cleaning member 112 when there is no need to distinguish them.

[0015] FIG. 1-2 shows an enlarged example of a schematic configuration of a part of the electrophotographic apparatus of the present disclosure. The photosensitive drum 103 rotates about the rotation axis 10. The rotation axis is a line perpendicular to the paper surface at the rotation axis 10, that is, the rotation axis direction refers to a direction perpendicular to the paper surface.

[0016] <Solid exposure device> FIG. 2 shows a cross-sectional view of the solid exposure head 201 as an example. A light-emitting substrate 202 on which a plurality of light-emitting elements 203 (LED chips) are arranged in the main scanning direction (the rotation axis direction of the photosensitive drum) and a lens array 206 in which a plurality of cylindrical refractive index distribution type lenses are arranged in the rotation axis direction of the photosensitive drum are held in the housing 205. The material of the housing 205 is a steel plate plated later with zinc plating or cold-rolled steel plate. The lens array 206 forms an image of the light beam emitted from the light-emitting element 203 as an equi-magnification erect image on the photosensitive drum 103. At this time, the distance from the light-emitting element 203 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 substantially equal. The distance between the light-emitting element 203 and the incident surface of the lens array 206 requires high precision on the order of μm. After precisely adjusting this distance, the light-emitting substrate 202 and the lens array 206 are fixed to the housing 205 by adhesion. In this embodiment, an LED is used as the solid exposure light source, and the integrated unit of the light-emitting substrate 202, the lens array 206, and the housing 205 is referred to as the solid exposure head 201.

[0017] <Cleaning member> As described above, when foreign matter such as toner adheres to the light-emitting surface of the lens array, the light emitted from the light-emitting element is partially blocked, resulting in a deterioration in the image quality of the output image. Therefore, it is necessary to periodically clean the light-emitting surface of the lens array. The image forming apparatus in the present disclosure has a cleaning member that is inserted between the surface of the photosensitive drum and the light-emitting surface of the lens array, and while rubbing the surface of the photosensitive drum and the light-emitting surface of the lens array from one end side to the other end side in the longitudinal direction of the lens array, the light-emitting surface of the lens array is cleaned. The cleaning member can also be called a lens array cleaning member. FIG. 3 is an example of an overall view of a cleaning member 300 for cleaning the solid exposure head 201 used in the present disclosure. The cleaning member 300 is generally elongated and rod-shaped, having a gripping portion 302 at one end of the rod-shaped body portion 303 and a cleaning portion 301 at the other end. The body portion 303 is formed of, for example, engineering plastics such as ABS or PP.

[0018] <Cleaning member and protection member> FIG. 4 shows a state in which the cleaning portion 301 of the cleaning member 300 is in contact with the lens array 206 for cleaning. The cleaning portion 301 includes a lens array rubbing portion 401 on the surface facing the lens array 206 and a drum rubbing portion 402 that rubs against the surface of the photosensitive drum on the surface facing the photosensitive drum 103. The lens array wiping part 401 can be a blade formed of a member such as urethane rubber, etc., and wipes the emission surface of the lens array 206 at the tip to remove foreign matter. As the material, in addition to urethane rubber, silicon rubber, chloroprene rubber, etc. may also be used. Also, a configuration where non-woven fabric or felt is selected instead of the blade for cleaning is also conceivable. The drum wiping part 402 is first used in a form that contacts the surface of the photosensitive drum in order to prevent, for example, damaging the surface of the photosensitive drum during the cleaning operation of the lens array 206. As the drum wiping part 402, a non-woven fabric or a felt-like composition of any known material may be used. Generally, it is mainly composed of a highly versatile material such as wool. As the drum wiping part 402, only one type of material may be used, or two or more types of materials may be used as a mixed material or copolymer. The form may be a woven fabric or a non-woven fabric. When using an animal-based material such as wool, the difference in the binding resin, etc. on the outermost surface of the photosensitive drum and the charging sequence becomes large, so strong frictional charging occurs between the drum wiping part 402 and the surface of the photosensitive drum 103 during the cleaning operation. The surface of the photosensitive drum 103 may be locally frictionally charged, and the potential difference between the wiped part and the non-wiped part may become large. As a result, there has been a problem that dust, dirt, waste toner, etc. in the machine are electrostatically locally attached to the surface of the photosensitive drum 103, causing image defects.

[0019] [Photosensitive drum] As an example of the configuration of the photosensitive drum 103 used in the present disclosure, a support, a subbing layer formed on the support, and a laminated photosensitive layer are shown in FIG. 5. In FIG. 5, 701 is the support, 702 is the subbing layer, 703 is the charge generation layer, and 704 is the hole transport layer. When the photosensitive drum 103 of the present disclosure further has a protective layer or the like on the hole transport layer 704, one more layer may be laminated on the hole transport layer 704.

[0020] <Support> As the support, those having conductivity (conductive support) are preferred. For example, supports made of metals (alloys) such as aluminum, iron, copper, gold, stainless steel, nickel, etc., supports made of metals or insulators with a conductive film provided on the surface, etc. can be mentioned. Examples of the insulator support include plastics such as polyester resin, polycarbonate resin, polyimide resin, glass, and paper supports. Further, examples of the conductive film include metal thin films such as aluminum, chromium, silver, gold, etc., thin films of conductive materials such as indium oxide, tin oxide, zinc oxide, etc., and thin films of conductive ink containing silver nanowires. In addition, examples of the shape of the support include a cylindrical shape, a film shape, etc. Among these, a cylindrical aluminum support is excellent in terms of mechanical strength, electrophotographic characteristics, and cost. Also, it may be used as a support as a bare tube, but for improving electrical characteristics and suppressing interference fringes, those subjected to physical treatments such as cutting, honing, and blasting on the surface of the bare tube, anodizing treatment, or chemical treatment using an acid, etc. may be used as the support.

[0021] <Conductive layer> The conductive layer is a layer that may be provided if necessary. The conductive layer is a layer that may be arranged on the support and between the support and the photosensitive layer. More specifically, for example, it may be arranged in the layer order of support / conductive layer / undercoat layer / photosensitive layer. By providing the conductive layer, it is possible to conceal scratches and unevenness on the support surface and control light reflection on the support surface. The conductive layer contains conductive particles and a resin. Examples of the material of the conductive particles include metal oxides, metals, carbon black, etc. Examples of the metal oxide include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, strontium titanate, magnesium oxide, antimony oxide, bismuth oxide, etc. Examples of the metal include aluminum, nickel, iron, nichrome, copper, zinc, silver, etc. Among the above materials of the conductive particles, metal oxides are preferred, and in particular, titanium oxide, tin oxide, and zinc oxide are more preferred. Regarding 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 itself such as phosphorus or aluminum or its oxide. Further, the conductive particles may have a laminated structure having 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 above silane coupling agent are much thicker than the latter in terms of thickness. When using a metal oxide as the conductive particles, the volume average particle diameter thereof is preferably 1 nm or more and 500 nm or less, and more preferably 3 nm or more and 400 nm or less.

[0022] Examples of 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 a concealer such as silicone oil, resin particles, and titanium oxide. The conductive layer can be obtained by providing a coating film of a coating liquid for a conductive layer containing the above materials and a solvent on a support and drying the coating film. Examples of the solvent used in the coating liquid include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, and aromatic hydrocarbon solvents. Examples of the dispersion 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 film 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.

[0023] <Undercoat layer> On the support or the conductive layer, an undercoat layer having a barrier function or an adhesion function may be provided as necessary. The undercoat layer can be obtained by dissolving a resin or the like in a solvent to prepare a coating solution for the undercoat layer, forming a coating film of the coating solution for the undercoat layer, and drying it. The undercoat layer has a resin and a substance for improving electrical properties. Each will be described. The undercoat layer contains a resin. The coating solution may be formed into a coating film (cured by polymerization of the monomer) by polymerizing a composition containing a monomer having a polymerizable functional group to obtain the undercoat layer as a cured film. Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinyl phenol resin, alkyd resin, polyvinyl alcohol resin, polyethylene oxide resin, polypropylene oxide resin, polyamide resin, polyamic acid resin, polyimide resin, polyamideimide resin, cellulose resin, and the like. Examples of the polymerizable functional group of the monomer having a polymerizable functional group include isocyanate group, blocked isocyanate group, methylol group, alkylated methylol group, epoxy group, metal alkoxide group, hydroxy group, amino group, carboxy group, thiol group, carboxylic anhydride group, carbon-carbon double bond group, and the like.

[0024] In addition, the undercoat layer contains an electron transport material, a metal oxide, a metal, etc. for the purpose of improving electrical properties. Among these, it is preferable to use an electron transport material and a metal oxide. Examples of the electron transport material include quinone compounds, imide compounds, benzimidazole compounds, cyclopentadienylidene compounds, fluorenone compounds, xanthone compounds, benzophenone compounds, cyanovinyl compounds, halogenated aryl compounds, silole compounds, boron-containing compounds, and the like. As the electron transport material, an electron transport material having a polymerizable functional group may be used and copolymerized with the above-mentioned monomer having a polymerizable functional group to form the undercoat layer as a cured film. Examples of the metal oxide include indium tin oxide, tin oxide, indium oxide, titanium oxide, zinc oxide, aluminum oxide, strontium titanate, silicon dioxide, etc. Examples of the metal include gold, silver, aluminum, etc.

[0025] The metal oxide contained in the undercoat layer may be surface-treated using a surface treatment agent such as a silane coupling agent before use. As a method for surface-treating the metal oxide, a general method is used. For example, a dry method or a wet method can be mentioned. In the dry method, while stirring the metal oxide in a mixer capable of high-speed stirring such as a Henschel mixer, an aqueous alcohol solution, an organic solvent solution, or an aqueous solution containing a surface treatment agent is added, and after uniformly dispersing, drying is performed. In the wet method, the metal oxide and the surface treatment agent are stirred in a solvent or dispersed using a sand mill or the like with glass beads or the like. After dispersion, the solvent is removed by filtration or distillation under reduced pressure. After removing the solvent, it is preferably baked at 100°C or higher.

[0026] The undercoat layer may further contain an additive. For example, known materials such as metal powders such as aluminum, conductive substances such as carbon black, metal chelate compounds, and organometallic compounds can be contained. The undercoat layer can be formed by preparing a coating solution for the undercoat layer containing each of the above materials and a solvent, forming this coating film on a support or a conductive layer, and drying and / or curing it. Examples of the solvent used in the coating solution for the undercoat layer include organic solvents such as alcohol, sulfoxide, ketone, ether, ester, aliphatic halogenated hydrocarbon, and aromatic compound. In the present disclosure, it is preferable to use an alcohol-based solvent or a ketone-based solvent. Examples of the dispersion method for preparing the coating solution for the undercoat layer include methods using a homogenizer, an ultrasonic disperser, a ball mill, a sand mill, a roll mill, a vibration mill, an attritor, or a liquid collision type high-speed disperser. When using an undercoat layer, the average film thickness is preferably 0.05 μm or more and 50 μm or less, and more preferably 0.3 μm or more and 25 μm or less.

[0027] <Charge generation layer> In the case of a laminated photosensitive drum, it is preferable to provide a charge generation layer as a photosensitive layer on the undercoat layer. The charge generation layer generally contains a charge generating substance and a binder resin. The photosensitive drum of the present disclosure has a photosensitive layer containing a bisazo compound having a specific structure represented by formula (1) as a charge generating substance. By using a compound having a structure with a chlorine atom at a site corresponding to the coupler residue of the bisazo compound, the above problems can be solved. Although the mechanism for improving the problems of the present disclosure has not been elucidated, it is considered that by using a charge generating substance having a specific structure, the potential difference due to local triboelectrification of the photosensitive drum is rapidly attenuated. It is considered that when the potential difference on the surface of the photosensitive drum is rapidly attenuated, the adhesion and accumulation of toner, dust, etc. on the local part of the surface of the photosensitive drum are suppressed, and image defects on the surface of the photosensitive drum are suppressed.

[0028] The specific structure of the azo compound represented by formula (1) is, for example, the structure shown below. Exemplary compound No. 1-1

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chem.

Chem.

[0029] In the azo compound represented by formula (1), at least one of R 10 , R 14 , R 15 and R 19 preferably represents a chlorine atom.

[0030] It is also possible to use a combination of charge generating materials other than the azo compound represented by formula (1). Examples include perylene pigments, anthraquinone derivatives, anthraanthrone derivatives, dibenzopyrenequinone 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 the phthalocyanine pigments, oxy titanium phthalocyanine, chloro gallium phthalocyanine, and hydroxy gallium phthalocyanine are preferred.

[0031] Examples of the binder resin used in the charge generation layer include polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, vinyl chloride, acrylic esters, methacrylic esters, vinylidene fluoride, and trifluoroethylene, polyvinyl alcohol resins, polyvinyl acetal resins, polyvinyl butyral resins, polycarbonate resins, polyester resins, polysulfone resins, polyphenylene oxide resins, polyurethane resins, cellulose resins, phenol resins, melamine resins, silicone resins, and epoxy resins. Among these, polyester resins, polycarbonate resins, and polyvinyl acetal resins are preferred, and polyvinyl acetal resins are more preferred. In the charge generation 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, more preferably in the range of 5 / 1 to 1 / 5. The charge generation layer can be formed by preparing a coating solution for the charge generation layer containing each of the above materials and a solvent, forming this coating film, and drying and / or curing it. Examples of the solvent used in the coating solution for the charge generation layer include alcohol solvents, sulfoxide solvents, ketone solvents, ether solvents, ester solvents, or aromatic hydrocarbon solvents. The film thickness of the charge generation layer is preferably 0.05 μm or more and 5 μm or less.

[0032] <Hole transport layer> The hole transport layer is obtained by dissolving or dispersing a hole transporting material and, if necessary, a binder resin in a solvent to prepare a coating solution for the hole transport layer, and forming and drying a coating film of the coating solution for the hole transport layer. When the protective layer described later is not provided, the hole transport layer becomes the surface layer of the photosensitive drum. Examples of the hole transporting material include triarylamine compounds, styryl compounds, benzidine compounds, hydrazone compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, triallylmethane compounds, etc. Also included are polymers having groups derived from these compounds in the main chain or side chain. Among these, as the hole transporting material, triarylamine compounds, styryl compounds, or benzidine compounds are preferred, and triarylamine compounds are particularly preferred. Also, the hole transporting material can be used alone or in combination of one or more kinds. Examples of the binder resin used for the hole transport layer include resins (insulating resins) such as polycarbonate resin, polyester resin, polyvinyl acetate resin, polysulfone resin, polystyrene resin, phenoxy resin, polyvinyl acetate resin, acrylic resin, phenoxy resin, polyacrylamide resin, polyamide resin, polyvinyl pyridine resin, cellulose-based resin, urethane resin, epoxy resin, agarose resin, cellulose resin, casein resin, polyvinyl alcohol resin, polyvinyl pyrrolidone resin, vinylidene chloride resin, acrylonitrile copolymer, and polyvinyl benzal resin. Further, organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinyl anthracene, and polyvinyl pyrene can also be used. Among these, polyester resin and polycarbonate resin are preferred. The copolymerization form of the polyester resin may be any form such as block copolymerization, random copolymerization, and alternating copolymerization. Among them, in the case of a random copolymer, it is preferable in terms of obtaining high abrasion resistance and scratch resistance.

[0033] <Polyester resin> In the image forming apparatus according to the present disclosure, it is preferable that the photosensitive drum has a surface layer containing a polyester resin having a structural unit represented by the following formula (4) and a structural unit represented by the following formula (5) as a binder resin. The structure of the polyester resin particularly preferable in the hole transport layer as the surface layer in the present embodiment is obtained from monomers having a structural unit derived from a dicarboxylic acid represented by the following formula (4) and a structural unit derived from a diol represented by the following formula (5).

Chemical formula

Chemical formula

[0034] Specific examples of the structural unit represented by formula (4) include the structural unit represented by the following formula (4-1), the structural unit represented by the following formula (4-2), the structural unit represented by the following formula (4-3), the structural unit represented by the following formula (4-4), and the structural unit represented by the following formula (4-5). Among these, it is preferable to have the structural unit represented by formula (4-1) or the structural unit represented by formula (4-4).

Chemical formula

[0035] Examples of the structural unit represented by formula (5) include, specifically, the structural unit represented by the following formula (5-1), the structural unit represented by the following formula (5-2), the structural unit represented by the following formula (5-3), the structural unit represented by the following formula (5-4), the structural unit represented by the following formula (5-5), the structural unit represented by the following formula (5-6), the structural unit represented by the following formula (5-7), the structural unit represented by the following formula (5-8), the structural unit represented by the following formula (5-9), the structural unit represented by the following formula (5-10), the structural unit represented by the following formula (5-11), the structural unit represented by the following formula (5-12), and the structural unit represented by the following formula (5-13). Among them, it is preferable to have a structure as shown in the structural unit represented by formula (5-3) or the structural unit represented by formula (5-10).

[0036]

Chemical formula

[0037] <Polycarbonate resin> In the image forming apparatus according to the present disclosure, it is preferable that the photosensitive drum has a surface layer containing a polycarbonate resin having a structural unit represented by the following formula (6) as a binder resin. In the hole transport layer as the surface layer in the present embodiment, a particularly preferable structure of the polycarbonate resin has a structural unit represented by the following formula (6).

Chemical formula

[0038] As the structural unit represented by formula (6), there may be mentioned a structural unit represented by the following formula (6-1), a structural unit represented by the following formula (6-2), a structural unit represented by the following formula (6-3), a structural unit represented by the following formula (6-4), a structural unit represented by the following formula (6-5), and a structural unit represented by the following formula (6-6). [Chemical formula]

[0039] These binder resins may be used alone, or two or more thereof may be used in combination as a mixture or copolymer. The copolymerization form may be any form such as a block copolymer, a random copolymer, an alternating copolymer, etc. Also, as these molecular weights, a range of weight average molecular weight (Mw) = 10,000 to 300,000 is preferable. These polycarbonate resins and polyester resins can generally be purchased and used as commercially available resins. Also, they can be synthesized by known methods. For example, they can be synthesized by the methods described in JP-A-2007-047655 and JP-A-2007-072277. The film thickness of the hole transport layer is preferably 1 μm or more and 100 μm or less, more preferably 3 μm or more and 50 μm or less, and even more preferably 5 μm or more and 40 μm or less.

[0040] [Protective layer] For the purpose of durability, high stabilization of electrical characteristics, imparting charging ability, etc., a protective layer may be provided as necessary. When providing a protective layer, it is preferable to form a film directly on top of the above hole transport layer. When the photosensitive drum has a protective layer, the protective layer becomes the surface layer. The protective layer is 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 it. Also, for improving durability, the protective layer is preferably formed by using a compound having a polymerizable functional group or the like, performing a post-film polymerization reaction by heating, ultraviolet irradiation, etc. after film formation, and polymerizing and curing it. As a configuration for polymerizing and curing the protective layer, a film-forming method may be used in which a compound having an acryloyloxy group or a compound having a methacryloyloxy group is chain-polymerized to produce a cured composition.

[0041] Further, in order to impart a hole transport function to the protective layer, the protective layer may be formed by curing a monomer having hole transport properties using various polymerization reactions and crosslinking reactions. Specifically, it is preferable to form a cured protective layer by polymerizing or crosslinking a hole-transporting compound having a chain-polymerizable functional group and curing it. Specifically, it is preferable to use a hole-transporting compound having an acryloyloxy group or a methacryloyloxy group.

[0042] In the image forming apparatus according to the present disclosure, it is preferable that the photosensitive drum has a surface layer containing a polymer of a composition containing a hole-transporting compound having a bifunctional acryloyloxy group or methacryloyloxy group represented by the following formula (2). The protective layer as the surface layer in the present embodiment preferably contains a polymer of a composition containing a hole-transporting compound having two acryloyloxy groups or methacryloyloxy groups represented by the following formula (2).

Chemical formula

[0043] Specific examples of the compound represented by formula (2) are shown below. Exemplified compound No. 2-1

Chemical formula

[0044] In addition, the image forming apparatus in the present disclosure preferably has a surface layer containing a polymer of a composition including a hole transporting compound having a monofunctional acryloyloxy group or methacryloyloxy group represented by the following formula (3), and a compound having an acryloyloxy group or methacryloyloxy group having no bifunctional or higher hole transporting property. The protective layer as the surface layer in the present embodiment preferably contains a polymer of a composition including a hole transporting compound having a monofunctional acryloyloxy group or methacryloyloxy group represented by the formula (3) and a compound having an acryloyloxy group or methacryloyloxy group having no bifunctional or higher hole transporting property in combination.

Chemical formula

[0045] Specific examples of the compound represented by formula (3) are shown below. Exemplary compound No. 3-1

Chemical formula

Chemical formula

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Chem.

Chem.

Chem.

Chem.

Chem.

Chem.

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Chem.

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Chem.

[0046] In Formula (2) and Formula (3), examples of the alkylene group having 1 to 4 carbon atoms represented by R 21 , R 22 , and R 31 include a methylene group, an ethylene group, an n-propylene group, an iso-propylene group, an n-butylene group, an iso-butylene group, a sec-butylene group, a tert-butylene group, and the like. In Formula (2) and Formula (3), R 25 , R 33 , and R 34Examples of the alkyl group having 1 to 4 carbon atoms, each represented by R, include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, and the like. In formulas (2) and (3), R 25 , R 33 , R 34 Examples of the alkoxy group having 1 to 4 carbon atoms, each represented by R, include a methoxy group, an ethoxy group, a propoxy group, an isopropoxy group, a butoxy group, a sec-butoxy group, a tert-butoxy group, and the like.

[0047] A polymerizable compound having no hole transporting property may be used simultaneously with the hole transporting compound having a chain polymerizable group. A polymerizable compound having an acryloyloxy group or a methacryloyloxy group is preferable. Specific examples include the substances listed below. The following examples have only an acryloyloxy group, but are not limited thereto, and compounds having a methacryloyloxy group instead of the acryloyloxy group may also be used. Exemplified Compound No. 11

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chem.

Chem.

[0048] When forming the protective layer, if it is possible to form a film only with a hole transporting compound having a chain polymerizable group mainly used for the protective layer, the polymerizable compound having no hole transporting property is not necessarily required to be used. That is, the surface layer in the present disclosure may include a polymer of a composition containing a hole transporting compound represented by formula (2) and a hole transporting compound represented by formula (3). However, in order to improve film formability, durability of the protective layer, electrical properties, etc., a compound having an acryloyloxy group or a methacryloyloxy group having no bifunctional or higher hole transporting property can be used. The surface layer in the present disclosure may include a polymer of a composition containing a hole transporting compound represented by formula (2) and a compound having an acryloyloxy group or a methacryloyloxy group having no bifunctional or higher hole transporting property.

[0049] In the present disclosure, when using a photosensitive drum for forming the protective layer, it has been shown that a protective layer containing a polymer of a composition containing a polymerizable compound having no hole transporting property can better improve the problems of the present disclosure. In particular, it has been found that the improvement effect is greatly enhanced when using a polymerizable compound having more polymerizable functional groups. In the polymerizable surface layer in the present disclosure, it is preferable to use a polymerizable compound having no hole transporting property and having a bifunctional or higher acryloyloxy group or methacryloyloxy group. In particular, it is preferable to use Exemplary Compounds No. 15 to 19.

[0050] In addition, for the surface layer in the present disclosure, for example, a hole-transporting compound represented by formula (2) and a compound having no hole-transporting property but having a trifunctional acryloyloxy group or methacryloyloxy group may be used. Also, for the surface layer in the present disclosure, for example, a hole-transporting compound represented by formula (3) and a compound having no hole-transporting property but having a trifunctional acryloyloxy group or methacryloyloxy group may be used. A hole-transporting compound represented by formula (3), a compound having no hole-transporting property but having a trifunctional acryloyloxy group or methacryloyloxy group, and a compound having no hole-transporting property but having a hexafunctional acryloyloxy group or methacryloyloxy group may also be used.

[0051] In addition, examples of the resin used for the protective layer include polyvinyl butyral resin, polyester resin, polycarbonate resin (such as polycarbonate Z resin, modified polycarbonate resin, etc.), nylon resin, polyimide resin, polyarylate resin, polyurethane resin, styrene-butadiene copolymer, styrene-acrylic acid copolymer, styrene-acrylonitrile copolymer, and melamine-guanamine resin. The film thickness of the protective layer is preferably 0.05 μm or more and 20 μm or less, and particularly preferably 0.5 μm or more and 10 μm or less. When providing a charge-transporting curable protective layer as described above, the film thickness of the protective layer is preferably 0.5 μm or more and 20 μm or less, and more preferably 1 μm or more and 10 μm or less.

[0052] As the coating method for each layer, coating methods such as dip coating method, spray coating method, spinner coating method, bead coating method, blade coating method, and beam coating method can be used. Among these, from the viewpoints of efficiency and productivity, the dip coating method is preferred.

Examples

[0053] The present disclosure will be described in more detail below with specific examples. "Parts" described below means "parts by mass". 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 thickness gauge (Fischerscope, manufactured by Fischer Instruments), a method using a spectroscopic interference thickness gauge (C-13027-11, manufactured by Hamamatsu Photonics), or a method of converting from the mass per unit area to specific gravity.

[0054] [Example 1] (Substrate) As the substrate (conductive substrate), a cylindrical aluminum cylinder (JIS-A3003, aluminum alloy, outer diameter 30 mm, length 357.5 mm, wall thickness 0.7 mm) subjected to cutting was used. Ultrasonic cleaning was performed in a cleaning solution containing a detergent (trade name: Chemicol CT, manufactured by Tokiwa Chemical Co., Ltd.) in pure water. Subsequently, after washing away the cleaning solution, ultrasonic cleaning was further performed in pure water for degreasing treatment, and this was used as the substrate.

[0055] (Undercoat layer) 40 parts by mass of titanium oxide particles (trade name: CR-EL, manufactured by Ishihara Sangyo Co., Ltd., specific surface area 6.8 m 2 / g, average particle diameter: 0.25 μm) and 100 parts by mass of methyl ethyl ketone were mixed and stirred for 1 hour. Subsequently, 12 parts of an alkyd resin solution (trade name: Beckolite M6401-50, manufactured by DIC Corporation) and 8 parts of a melamine resin solution (Super Beckamine G-821-60, manufactured by DIC Corporation) were further mixed with 100 parts of methyl ethyl ketone. This was dispersed for 2 hours at 23 ± 3 °C in an atmosphere using a sand mill apparatus with glass beads having a diameter of 0.8 mm to prepare a coating solution for the undercoat layer. The obtained coating solution for the undercoat layer was dip-coated on the substrate to form a coating film, and the coating film was dried at 150 °C for 30 minutes to form an undercoat layer with a film thickness of 5 μm.

[0056] (Charge generation layer 1) 5 parts of a bisazo compound (Exemplary Compound No. 1-3) as a charge generating substance and 2 parts of a polyvinyl butyral resin (Esrec BX-1, manufactured by Sekisui Chemical Co., Ltd.) as a binder resin were prepared. Using 250 parts of cyclohexanone and 100 parts of 2-butanone as solvents, glass beads with a diameter of 1 mm were used in a sand mill disperser, and all of the solvent in which polyvinyl butyral was dissolved and the azo pigment were added. Dispersion was carried out for 24 hours at a rotation speed of 600 rpm to prepare a coating solution for the charge generation layer. This coating solution for the charge generation layer was dip-coated onto the undercoat layer, and the obtained coating film was dried at 90 °C for 10 minutes to form a charge generation layer 1 with a film thickness of 0.2 μm.

[0057] (Hole transport layer 1) 100 parts of a hole transporting compound represented by the following formula (A) and 100 parts of a bisphenol Z-type polycarbonate resin having a structural unit represented by formula (6-3) (trade name: Iupilon Z400, manufactured by Mitsubishi Engineering-Plastics Corporation) were prepared. These were dissolved in a mixed solvent of 272 parts of o-xylene, 230 parts of methyl benzoate, and 272 parts of dimethoxymethane to prepare a coating solution for the hole transport layer. This coating solution for the hole transport layer was dip-coated onto the charge generation layer to form a coating film, and the obtained coating film was dried at 115 °C for 50 minutes to form a hole transport layer 1 with a film thickness of 18 μm. [Chemical formula]

[0058] (Protective layer 1) The following materials were mixed and stirred well. · 100 parts of Exemplary Compound No. 2-5 as a hole transporting compound represented by formula (2) · 100 parts of 1-propanol · 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (trade name: AE-3000, manufactured by AGC Inc.) 100 parts Subsequently, filtration was performed using a membrane filter (product name: FP-045, manufactured by Sumitomo Electric Fine Polymer Co., Ltd.) to prepare a coating solution for the protective layer. This coating solution for the protective layer was dip-coated onto the hole transport layer 1 to form a coating film, and the obtained 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 the conditions of an acceleration voltage of 70 kV and an absorption dose of 15 kGy in a nitrogen atmosphere. Subsequently, heat treatment was performed for 15 seconds under the condition that the temperature of the coating film reached 135 °C in a nitrogen atmosphere. The oxygen concentration from the electron beam irradiation to the heat treatment for 15 seconds was 15 ppm. Next, in the air, it was naturally cooled until the temperature of the coating film reached 25 °C, and then heat treatment was performed for 1 hour under the condition that the coating film reached 105 °C to form a protective layer 1 with a film thickness of 5 μm. In this way, a photosensitive drum 1 having a support, an undercoat layer, a charge generation layer 1, a hole transport layer 1, and a protective layer 1 before surface polishing was produced.

[0059] <Surface processing of the photosensitive drum> (Polishing the surface of the photosensitive drum) The surface of the photosensitive drum 1 before forming the surface shape was polished. The polishing was performed using a polishing apparatus and a polishing sheet under the following conditions. Feed speed of the polishing sheet; 400 mm / min Rotation speed of the photosensitive drum; 450 rpm Pushing-in of the photosensitive drum to the backup roller; 3.5 mm Rotation direction of the polishing sheet and the photosensitive drum; with Backup roller; outer diameter 100 mm, Asker C hardness 25 The polishing sheet A mounted on the polishing apparatus was prepared by mixing polishing abrasive grains used for GC3000 and GC2000 manufactured by Riken Korundum Co., Ltd. GC3000 (polishing sheet surface roughness Ra 0.83 μm) GC2000 (polishing sheet surface roughness Ra 1.45 μm) Polishing sheet A (polishing sheet surface roughness Ra 1.12 μm) The polishing time using the polishing sheet A was 20 seconds.

[0060] (Measurement of Polishing Depth L (μm)) For the photosensitive drum after polishing, the maximum height Rmax was measured in accordance with JIS B 0601 1982 using a surface roughness measuring instrument Surfcoader SE3500 type manufactured by Kosaka Laboratory Ltd. The measurement conditions were set as follows. The measurement was performed arbitrarily at three locations within a 5 mm square range of the photosensitive drum after polishing, and the average value was adopted as the polishing depth L (μm). The polishing depth L of the photosensitive drum after surface polishing was 0.75 μm. Also, in Examples 2 to 8, Comparative Examples 1 and 2 described later, the polishing depth L of the photosensitive drum subjected to surface processing was all 0.75 μm. (Measurement Conditions) Detector: R2μm Stylus: Diamond needle with 0.7 mN Filter: 2CR Cutoff value: 0.08 mm Measurement length: 2.5 mm Feed speed: 0.1 mm / second

[0061] [Example 2] Up to the hole transport layer was fabricated in the same manner as in Example 1. The protective layer was formed under the following conditions instead of the protective layer 1 in Example 1. (Protective Layer 2) The following materials were mixed and stirred well. · 80 parts of Exemplified Compound No. 2-5 as the hole transporting compound represented by Formula (2) · 20 parts of Exemplified Compound No. 16 as the polymerizable compound having no hole transporting property · 100 parts of 1-propanol · 1,1,2,2-tetrafluoroethyl-2,2,2-trifluoroethyl ether (trade name: AE-3000, manufactured by AGC Inc.) 100 parts Thereafter, filtration was performed using a membrane filter (trade name: FP-045, manufactured by Sumitomo Electric Fine Polymer Inc.) to prepare a coating solution for the protective layer. A protective layer 2 was formed on the hole transport layer in the same manner as in Example 1, and surface processing was performed in the same manner to fabricate a photosensitive drum 2.

[0062] [Example 3] Up to the hole transport layer was formed in the same manner as in Example 1. The protective layer was formed under the following conditions instead of the protective layer 1 in Example 1. (Protective layer 3) The following materials were mixed and stirred well. · As the hole transporting compound represented by formula (3), 30 parts of Exemplary Compound No. 3-6 · As the hole transporting compound represented by formula (2), 70 parts of Exemplary Compound No. 2-5 · 100 parts of 1-propanol · 1,1,2,2-Tetrafluoroethyl-2,2,2-trifluoroethyl ether 100 parts Thereafter, filtration was performed using a membrane filter (trade name: FP-045, manufactured by Sumitomo Electric Fine Polymer Co., Ltd.) to prepare a coating solution for the protective layer. A protective layer 3 was formed on the hole transport layer in the same manner as in Example 1, and surface treatment was performed in the same manner to produce a photosensitive drum 3.

[0063] [Example 4] Up to the hole transport layer was produced in the same manner as in Example 1. The protective layer was formed under the following conditions instead of the protective layer 1 in Example 1. (Protective layer 4) The following materials were mixed and filtered to adjust a coating solution for the protective layer. · As the hole transporting compound represented by formula (3), 8 parts of Exemplary Compound No. 3-17 · As a polymerizable compound having no hole transporting property, trimethylolpropane triacrylate (Exemplary Compound No. 15) having a trifunctional chain polymerizable group, 10 parts · As a photoinitiator, 0.5 part of 1-hydroxycyclohexyl phenyl ketone (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals) · 700 parts of tetrahydrofuran · 200 parts of cyclohexanone On the hole transport layer of the photosensitive drum, the above coating solution for the protective layer was applied by spray coating method, dried and cured to form a 5-μm protective layer 4 to produce a photosensitive drum. The curing conditions at this time were as follows: in an atmosphere with an oxygen concentration of 5%, using a metal halide type ultraviolet irradiation device with 120 W / cm, ultraviolet irradiation was performed at a speed of 8 m / min to form the protective layer 4. Thereafter, surface treatment was performed in the same manner as in Example 1 to produce the photosensitive drum 4.

[0064] [Example 5] Up to the hole transport layer was produced in the same manner as in Example 1. The protective layer was formed under the following conditions instead of the protective layer 4 in Example 4. (Protective layer 5) The following materials were mixed. · As the hole transporting compound represented by formula (3), 8 parts of Exemplified Compound No. 3-17 · As the polymerizable compound having no hole transporting property, trimethylolpropane triacrylate (Exemplified Compound No. 15) (trade name: KAYARAD TMPTA, manufactured by Nippon Kayaku Co., Ltd.) having a trifunctional chain polymerizable group, 4 parts · As the polymerizable compound having no hole transporting property, a polymerizable compound (Exemplified Compound No. 18) (trade name: KAYARAD DPCA-120, manufactured by Nippon Kayaku Co., Ltd.) having a hexafunctional chain polymerizable group, 4 parts · As the photoinitiator, 1-hydroxycyclohexyl phenyl ketone (trade name: Irgacure 184, manufactured by Ciba Specialty Chemicals), 0.5 part · Tetrahydrofuran, 700 parts · Cyclohexanone, 200 parts These mixed solutions were stirred to be uniform, and then filtered through a polytetrafluoroethylene filter (trade name: PF-040, manufactured by Advantec Toyo Co., Ltd.) to prepare a coating solution for the protective layer. Except as described above, a protective layer 5 was formed on the hole transport layer in the same manner as in Example 4, and surface treatment was performed in the same manner to produce the photosensitive drum 5.

[0065] [Example 6] A photosensitive drum 6 was produced in the same manner as in Example 5, except that the bisazo compound, which is the charge generating substance used in the charge generation layer, was changed to Exemplified Compound No. 1-2.

[0066] [Example 7] A photosensitive drum 7 was produced in the same manner as in Example 5, except that the bisazo compound, which is a charge generating substance used in the charge generation layer, was changed to Exemplary Compound No. 1-1.

[0067] [Example 8] A photosensitive drum 8 was produced in the same manner as in Example 5, except that the bisazo compound, which is a charge generating substance used in the charge generation layer, was changed to Exemplary Compound No. 1-6.

[0068] [Example 9] Up to the charge generation layer was produced in the same manner as in Example 1. Next, the hole transport layer 2 was formed as follows. (Hole Transport Layer 2) 80 parts of a hole transporting compound represented by formula (A) and 100 parts of a polyester resin having a structural unit represented by formula (4-1) and a structural unit represented by formula (5-6) as a binder resin were prepared. These were dissolved in a mixed solvent of 280 parts of o-xylene, 265 parts of methyl benzoate, and 265 parts of dimethoxymethane to prepare a coating solution for the hole transport layer. This coating solution for the hole transport layer was dip-coated on the charge generation layer to form a coating film, and the obtained coating film was dried at 115°C for 50 minutes to form a hole transport layer 2 with a film thickness of 24 μm, and a photosensitive drum 9 was produced. In this example, the hole transport layer 2 becomes the surface layer.

[0069] [Example 10] Up to the charge generation layer was produced in the same manner as in Example 1. Next, the hole transport layer 3 was formed as follows. (Hole Transport Layer 3) 80 parts by mass of a hole transporting compound represented by formula (A), 94 parts of a polycarbonate resin having a structural unit represented by formula (6-3) as a binder resin, and 6 parts of a polycarbonate resin having a structural unit represented by formula (6-4) were mixed and used. These were dissolved in a mixed solvent of 275 parts of o-xylene, 265 parts of methyl benzoate, and 260 parts of dimethoxymethane to prepare a coating solution for the hole transport layer. The coating solution for the hole transport layer was dip-coated on the charge generation layer to form a coating film, and the obtained coating film was dried at 115°C for 50 minutes to form a hole transport layer 3 with a film thickness of 24 μm, thereby fabricating a photosensitive drum 10. In this example, the hole transport layer 3 serves as the surface layer.

[0070] [Comparative Example 1] In the photosensitive drum fabricated in Example 5, a photosensitive drum 11 was fabricated in the same manner as in Example 5, except that the bisazo compound, which is the charge generating substance used in the charge generation layer, was changed to the following Comparative Compound No. 1.

[0071] [Comparative Example 2] In the photosensitive drum fabricated in Example 5, a photosensitive drum 12 was fabricated in the same manner as in Example 5, except that the bisazo compound, which is the charge generating substance used in the charge generation layer, was changed to the following Comparative Compound No. 2.

[0072] [Comparative Example 3] In the photosensitive drum fabricated in Example 9, a photosensitive drum 13 was fabricated in the same manner as in Example 9, except that the bisazo compound, which is the charge generating substance used in the charge generation layer, was changed to the following Comparative Compound No. 2.

[0073] [Comparative Example 4] In the photosensitive drum fabricated in Example 10, a photosensitive drum 14 was fabricated in the same manner as in Example 10, except that the bisazo compound, which is the charge generating substance used in the charge generation layer, was changed to the following Comparative Compound No. 2.

[0074] [Comparative Compounds] Comparative Compound No. 1 [Chemical Formula] Comparative Compound No. 2 [Chemical Formula]

[0075] [Evaluation] A cleaning member (lens array cleaning rod) having the configuration shown in FIG. 3 was prepared. As the drum rubbing portion in the cleaning member, a wool felt material was used. For each photosensitive drum manufactured above, evaluation of adhesion, as well as evaluation of drum scratches and images, were performed in a normal temperature and low humidity environment (temperature 23°C, relative humidity 15%). In the evaluation, a modified machine provided with the solid exposure mechanism exemplified above was used for the portion from which the exposure unit of the multifunction machine imageRUNNER ADVANCE C5870F (registered trademark) manufactured by Canon Inc. was removed.

[0076] (Evaluation of Adhesion) In this evaluation, after passing 1000 sheets of paper through the multifunction machine with each photosensitive drum set, while rubbing each photosensitive drum with the above cleaning rod for the lens array, 10 wiping operations were performed on the lens array, each photosensitive drum was removed from the multifunction machine, and the deposits on the surface of each photosensitive drum were observed. For the observation of the deposits on the surface of the photosensitive drum, a halogen lamp was used as the inspection light, and a line sensor with 8192 pixels (Keyence Corporation: XG-HL08M) was used as the imaging means. The inspection light was arranged at an angle of 45° with respect to the normal of the photosensitive drum, the line camera was arranged at an angle of 45° symmetric to the inspection light with respect to the same normal, and while rotating the photosensitive drum at a speed of 60 rpm, the specularly reflected light was imaged to obtain an image with a resolution of 44 μm / pixel. From this image, by obtaining the difference between the image smoothed using a small smoothing filter and the image smoothed using a large smoothing filter, an image with large-scale gradation removed from the small smoothed image was obtained. Next, binarization processing was performed with a white-side threshold of 20 and a black-side threshold of -25, points where the area of white or black was 20 pix × 20 pix or more were regarded as deposits, and the total number of defect points on the entire surface was counted. The counted number of defect points was determined according to the following evaluation criteria A to C. If the evaluation result is C or more, it can be judged that the effect of the present disclosure is obtained. A: In the entire field of view, the number of defects is 3 or less B: In the entire field of view, the number of defects is more than 3 and 10 or less C: In the entire field of view, the number of defects is more than 10 and 30 or less D: In the entire field of view, the number of defects is more than 30

[0077] (Evaluation of drum scratches) After evaluating the adhesion, each photosensitive drum was set in a multifunction printer, and 10,000 sheets of paper were passed through. Then, the photosensitive drum was removed from the multifunction printer, and the scratches on the surface of the photosensitive drum were observed with a microscope. A: There were no scratches or almost no scratches. B: There were scratches up to about 3 μm at most, but there was no influence on the output image. C: The scratches reached 3 μm or more, and the output image was affected.

[0078] (Sensitivity evaluation) For the photosensitive drums 1 to 14 of Examples 1 to 10 and Comparative Examples 1 to 4, the sensitivity was evaluated in a normal temperature and humidity environment of 23°C / 50% relative humidity. A multifunction printer imageRUNNER ADVANCE C5870F manufactured by Canon Inc. was modified so that the charging potential (dark part potential) and exposure light amount of the photosensitive drum could be adjusted, and it was used as an evaluation device. The photosensitive drum prepared above was mounted on the process cartridge (cyan color) of the evaluation device, and in an environment of 23°C and 50% relative humidity, an image output was performed on A4-sized plain paper using a test chart with a printing ratio of 4%. At this time, as the charging condition, the applied bias was adjusted so that the charging potential (dark part potential) of the photosensitive drum became -500 V. As the exposure condition, the exposure light amount was adjusted to be 0.3 μJ / cm 2 The sensitivity of the photosensitive drum was evaluated from the bright part potential of the photosensitive drum. Note that the smaller the absolute value of the bright part potential value of the photosensitive drum, the higher the sensitivity of the photosensitive drum. The bright part potential of the photosensitive drum was measured by the following method. The bright part potential of the photosensitive drum was measured using a surface potentiometer (model 344, manufactured by Trek) by removing the developing device from the process cartridge of the evaluation device and placing a potential measurement probe (product name: model 6000B-8, manufactured by Trek) at the developing position. The position of the potential measurement probe with respect to the photosensitive drum was the center in the axial direction of the photosensitive drum, and the distance between the surface of the photosensitive drum and the measurement surface of the potential measurement probe was 3 mm. ​Table 1 shows the "sensitivity rank" corresponding to the magnitude of the light portion potential as a simple sensitivity index. The values of the light portion potential for each rank are as follows. A: The light portion potential was -160 V or more (very good sensitivity) B: The light portion potential was -200 V or more and less than -160 V (good sensitivity) C: The light portion potential was less than -200 V (poor sensitivity)

[0079]

Table 1

[0080] Embodiments of the present invention include the following configurations. (Configuration 1) A photosensitive drum rotatable about a rotation axis, A plurality of light-emitting elements for emitting exposure light irradiated on the surface of the photosensitive drum, A lens array having a light incident surface facing the light-emitting element and a light exit surface facing the photosensitive drum, in which a plurality of lenses for condensing the exposure light emitted from the light-emitting element on the surface of the photosensitive drum are arranged in the rotation axis direction, A cleaning member inserted between the surface of the photosensitive drum and the light exit surface of the lens array, and cleaning 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 cleaning member has a drum rubbing portion that rubs against the surface of the photosensitive drum, The photosensitive drum has a photosensitive layer containing an azo compound represented by the following formula (1), characterized by the image forming apparatus.

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Chemical formula

Explanation of symbols

[0081] 10 Rotation shaft 101 Paper feeding part 103Y, 103M, 103C, 103K Photosensitive drum 201Y, 201M, 201C, 201K Solid exposure head 203 Light emitting element 206 Lens array 300 Cleaning member

Claims

1. A photosensitive drum rotatable about a rotation axis, a plurality of light-emitting elements for emitting exposure light 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, in which a plurality of lenses for condensing the exposure light emitted from the light-emitting elements onto the surface of the photosensitive drum are arranged in the direction of the rotation axis, a cleaning member inserted between the surface of the photosensitive drum and the light exit surface of the lens array, and configured to clean 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 in the longitudinal direction of the lens array to the other end side, An image forming apparatus comprising: wherein the cleaning member has a drum rubbing portion that rubs against the surface of the photosensitive drum, wherein the photosensitive drum has a photosensitive layer containing an azo compound represented by the following formula (1), an image forming apparatus characterized by this. 【Chemical 1】 (In formula (1), R １０ ~R １９ each independently represents a hydrogen atom, a halogen atom, a nitro group, a cyano group, an alkyl group having 2 or fewer carbon atoms, an alkoxy group having 2 or fewer carbon atoms, or a trifluoromethyl group. However, at least one of R １０ ~R １９ in the formula (1) represents a chlorine atom.)

2. R in the formula (1) above １０ , R １４ , R １５ and R １９ The image forming apparatus according to claim 1, wherein at least one of them represents a chlorine atom.

3. The image forming apparatus according to claim 1 or 2, wherein the photosensitive drum has a surface layer containing a polymer of a composition containing a hole transporting compound having a bifunctional acryloyloxy group or methacryloyloxy group represented by the following formula (2). 【Chemical 2】 (In formula (2), R ２１ , R ２２ each independently represents an alkylene group having 1 to 4 carbon atoms. R ２３ , R ２４ represents a hydrogen atom or a methyl group. R ２５ represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. n ２１ represents a number from 0 to 3.)

4. The photosensitive drum is a hole transporting compound having a monofunctional acryloyloxy group or methacryloyloxy group represented by the following formula (3), and a compound having an acryloyloxy group or methacryloyloxy group having no bifunctional or higher hole transporting property, the image forming apparatus according to claim 1 or 2, having a surface layer containing a polymer of a composition containing the same. [Chemical Formula 3] (In formula (3), R ３１ represents an alkylene group having 1 to 4 carbon atoms. R ３２ represents a hydrogen atom or a methyl group. R ３３ , R ３４ each independently represents an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms. n ３１ represents a number of 0 or 1. n ３２ represents a number of 0 or 1. n ３３ represents a number of 0 or 1. However, when n ３３ is 0, n ３２ is also 0. n ３２ and n ３３ are both 0, the bond between the oxygen atom of the acryloyloxy group or methacryloyloxy group and the benzene ring is a single bond. n ３４ , n ３５ each independently represents a number from 0 to 3. )

5. The image forming apparatus according to claim 1 or 2, wherein the photosensitive drum has a surface layer containing a polyester resin having a structural unit represented by the following formula (4) and a structural unit represented by the following formula (5) as a binder resin. 【Chemical Formula 4】 【Chemical Formula 5】 (In formula (4), X ４１ represents an m-phenylene group, a p-phenylene group, a divalent group in which two p-phenylene groups are bonded via a single bond or an oxygen atom, or a naphthylene group.) In formula (5), X ５１ represents a single bond, an oxygen atom, a substituted or unsubstituted alkylidene group, or a substituted or unsubstituted cycloalkylidene group. R ５１ to R ５８ each independently represents a hydrogen atom or an alkyl group.)

6. The image forming apparatus according to claim 1 or 2, wherein the photosensitive drum has a surface layer containing a polycarbonate resin having a structural unit represented by the following formula (6) as a binder resin. [Chemical Formula 6] (In formula (6), X ６１ represents a single bond, an oxygen atom, an alkylidene group or a cycloalkylidene group. R ６１ to R ６８ each independently represents a hydrogen atom or an alkyl group.)

7. The image forming apparatus according to claim 1 or 2, wherein the drum rubbing portion contains wool.

Images