Image forming apparatus

Abstract

To provide an image forming apparatus that suppresses fluctuations in image density over a long period of time and is less prone to the occurrence of streaky image defects. [Solution] The image forming apparatus comprises a photoreceptor having a surface layer with a transmittance of 5% to 95% of light with a wavelength of 1000 nm, a charging device, an electrostatic latent image forming device, a developing device, a transfer device, and a photoreceptor cleaning device. The contact portion of the cleaning blade that contacts the photoreceptor contains polyurethane rubber polymerized from at least a polyol component and a polyisocyanate component, the ratio of 100% modulus M100 (MPa) to rebound modulus Re (%) M100 / Re is 0.25 or more, the rebound modulus Re is less than 25%, and the tensile stress at 200% strain at a temperature of 23°C is 15 MPa or more.

Description

Technical Field

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

Background Art

[0002] In Patent Document 1, there is disclosed a cleaning device having an elastic blade that contacts a cleaning target in a counter direction and removes deposits adhering to the surface of the cleaning target, wherein the ratio of fluorine element when measuring the tip surface, which is the end surface in the longitudinal direction of the elastic blade of the elastic blade, by X-ray photoelectron spectroscopy is 16.3 atomic% or more.

[0003] In Patent Document 2, in an image forming apparatus including a photoreceptor and a cleaning blade whose tip ridge line portion contacts the surface of the photoreceptor, the photoreceptor has a crosslinked resin surface layer made of acrylic or / and methacrylic resin, and the tip ridge line portion of the cleaning blade has a laminated structure of a base material made of an elastic body, a mixed layer of the base material and acrylic or / and methacrylic resin, and a surface layer made of acrylic or / and methacrylic resin layer.

[0004] In Patent Document 3, there is disclosed an image forming apparatus including a cleaning blade having a 100% modulus at 23°C of 17 MPa or more and 23 MPa or less.

[0005] In Patent Document 4, there is disclosed an electrophotographic photoreceptor having a surface layer containing fluorine atom-containing resin fine particles. In Patent Document 5, there is disclosed an electrophotographic photoreceptor having a protective layer containing aluminum-doped zinc oxide particles. In Patent Document 6, there is disclosed an electrophotographic photoreceptor having a protective layer containing silica particles.

Prior Art Documents

Patent Documents

[0006]

Patent Document 1

[0007] The object of this disclosure is to provide an image forming apparatus that suppresses fluctuations in image density over a long period of time and is less prone to the occurrence of streaky image defects. [Means for solving the problem]

[0008] The following embodiments are included as specific means for solving the aforementioned problems. <1> A photoreceptor having a surface layer with a transmittance of 5% or more and 95% or less for light with a wavelength of 1000 nm, A charging device for charging the surface of the photoreceptor, An electrostatic latent image forming apparatus for forming an electrostatic latent image on the surface of the charged photoreceptor, A developing apparatus that develops an electrostatic latent image formed on the surface of a photoreceptor using a developer containing toner to form a toner image, A transfer device for transferring the toner image onto the surface of a recording medium, A photoreceptor cleaning device having a cleaning blade that contacts the surface of the photoreceptor, for cleaning the surface of the photoreceptor, The contact portion of the cleaning blade that contacts the photoreceptor contains polyurethane rubber polymerized from at least a polyol component and a polyisocyanate component, the ratio of 100% modulus M100 (MPa) to rebound modulus Re (%) M100 / Re is 0.25 or more, the rebound modulus Re is less than 25%, and the tensile stress at 200% strain at a temperature of 23°C is 15 MPa or more. Image forming apparatus. <2> The ratio M100 / Re is 0.28 or more and 1.0 or less. <1> The image forming apparatus described above. <3> The cleaning blade is a laminate of polyurethane rubber. <1> or <2> An image forming apparatus as described in any one of the following. <4> The surface layer of the photoreceptor contains at least one filler particle selected from the group consisting of organic particles and inorganic particles. <1> ~ <3> An image forming apparatus as described in any one of the following. <5> The surface layer of the photoreceptor is a layer formed by curing a composition containing monomers having polymerizable functional groups and fluororesin particles. <1> ~ <4> An image forming apparatus as described in any one of the following. <6> The surface layer of the photoreceptor is a layer formed by curing a composition containing an ultraviolet-curable acrylic resin and at least one particle selected from the group consisting of metal oxide particles and silica particles. <1> ~ <4> An image forming apparatus as described in any one of the following. [Effects of the Invention]

[0009] <1> , <3> , <4> , <5> or <6> According to this, an image forming apparatus is provided that is less prone to generating streaky image defects compared to an image forming apparatus in which the ratio M100 / Re is less than 0.25, the rebound modulus Re is 25% or more, or the tensile stress is less than 15 MPa. <2> According to this, an image forming apparatus is provided that is less prone to producing streaky image defects compared to an image forming apparatus with a ratio M100 / Re of less than 0.28 or greater than 1.0. [Brief explanation of the drawing]

[0010] [Figure 1] This is a schematic diagram showing an example of an image forming apparatus according to this embodiment. [Figure 2] This is a schematic diagram showing another example of the image forming apparatus according to this embodiment. [Figure 3] This is a partial cross-sectional view showing an example of the layer structure of the photoreceptor in this embodiment. [Figure 4] This is a partial cross-sectional view showing another example of the layer configuration of the photoreceptor in this embodiment. [Figure 5] This is a schematic diagram showing an example of a cleaning blade in this embodiment. [Modes for carrying out the invention]

[0011] The embodiments of this disclosure are described below. These descriptions and embodiments are illustrative and do not limit the scope of the embodiments.

[0012] In this disclosure, the numerical range indicated using "~" represents a range that includes the numbers before and after "~" as the minimum and maximum values, respectively. In numerical ranges described in stages within this disclosure, the upper or lower limit of one numerical range may be replaced with the upper or lower limit of another numerical range described in stages. Furthermore, in numerical ranges described within this disclosure, the upper or lower limit of that range may be replaced with the values ​​shown in the examples.

[0013] In this disclosure, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes, provided that their objectives are achieved.

[0014] When embodiments are described in this disclosure with reference to the drawings, the configuration of such embodiments is not limited to the configuration shown in the drawings. Furthermore, the sizes of the components in each figure are conceptual, and the relative relationships between the components are not limited thereto.

[0015] In this disclosure, each component may contain multiple types of the corresponding substance. When referring to the amount of each component in a composition in this disclosure, if there are multiple types of the substance corresponding to each component in the composition, it means the total amount of those multiple types of substances present in the composition unless otherwise specified. In this disclosure, each component may contain multiple types of particles. If multiple types of particles corresponding to each component are present in the composition, the particle size of each component refers to the value for a mixture of such multiple types of particles present in the composition, unless otherwise specified.

[0016] In this disclosure, alkyl groups and alkylene groups include linear, branched, and cyclic groups unless otherwise specified. In this disclosure, organic groups, aromatic rings, linking groups, alkyl groups, alkylene groups, aryl groups, aralkyl groups, alkoxy groups, aryloxy groups, etc., may have hydrogen atoms in the group substituted with halogen atoms. In this disclosure, when compounds are shown by structural formulas, the symbols representing carbon atoms and hydrogen atoms (C and H) in the hydrocarbon group and / or hydrocarbon chain may be omitted.

[0017] In this disclosure, "photosensitive material" refers to "electrophotographic photosensitive material." In this disclosure, the "axial direction" of the photoreceptor means the direction in which the rotation axis of the photoreceptor extends, and the "circumferential direction" of the photoreceptor means the direction of rotation of the photoreceptor.

[0018] <Image forming apparatus> The image forming apparatus according to this embodiment is A photoreceptor having a surface layer with a transmittance of 5% or more and 95% or less for light with a wavelength of 1000 nm, A charging device that charges the surface of the photoreceptor, An electrostatic latent image forming apparatus that forms an electrostatic latent image on the surface of a charged photoreceptor, A developing apparatus that uses a developer containing toner to develop an electrostatic latent image formed on the surface of a photoreceptor and form a toner image, A transfer device that transfers a toner image onto the surface of a recording medium, The device comprises a photoreceptor cleaning device having a cleaning blade that contacts the surface of the photoreceptor and cleaning the surface of the photoreceptor.

[0019] For the surface layer of a photoreceptor to have a transmittance of 5% to 95% of light at a wavelength of 1000 nm, this means that the surface layer contains at least one type of filler particle selected from the group consisting of organic and inorganic particles, and that the surface layer is a relatively hard layer. The inclusion of filler particles increases the hardness of the surface layer, improving the abrasion resistance of the photoreceptor.

[0020] In this embodiment, the transmittance of the surface layer of the photoreceptor at a wavelength of 1000 nm is a value measured by the following measurement method. A sample of the surface layer obtained by scraping the surface layer from the photoreceptor is attached to a glass plate. Transmittance is measured using a UV-Vis spectrophotometer (UV2600, Shimadzu Corporation). The wavelength is set to 1000 nm in transmittance measurement mode, and the measured value is read.

[0021] The transmittance of light at a wavelength of 1000 nm in the surface layer of the photoreceptor can be controlled by incorporating an appropriate amount of filler particles into the surface layer. The filler particles may be organic particles, inorganic particles, or a mixture of organic and inorganic particles.

[0022] The cleaning blade of the image forming apparatus according to this embodiment contains, at least, a polyurethane rubber polymerized from at least a polyol component and a polyisocyanate component in the contact portion that contacts the photoreceptor, with a ratio of 100% modulus M100 (MPa) to rebound modulus Re (%) M100 / Re of 0.25 or more, a rebound modulus Re of less than 25%, and a tensile stress of 15 MPa or more at 200% strain at a temperature of 23°C.

[0023] The cleaning blade may have a single-layer structure consisting only of a contact portion having the above-described characteristics (hereinafter referred to as "contact member"), a two-layer structure consisting of a first layer made of the contact member and a second layer supporting the first layer, or a structure consisting of three or more layers. The cleaning blade may have a structure in which only the contact portion that comes into contact with the photoreceptor is made of a material having the above-described characteristics, and the surrounding area is made of other materials.

[0024] The image forming apparatus according to this embodiment suppresses fluctuations in image density (decrease or increase in image density) over a long period of time, and is less prone to the occurrence of streaky image defects. The mechanism is thought to be as follows.

[0025] To extend the lifespan of a photoreceptor, it is advisable to increase its wear resistance by providing a relatively hard surface layer. When wear on the photoreceptor's surface layer is suppressed, the photoreceptor's electrical properties are maintained, and image density is less likely to fluctuate over long periods. However, the excellent wear resistance of the surface layer can suppress the refreshing of the outer surface of the photoreceptor, causing toner components to adhere and resulting in film formation (the formation of a film), which can cause fluctuations in image density. To suppress film formation on the outer surface of the photoreceptor, it is preferable to harden at least the portion of the cleaning blade that contacts the outer surface of the photoreceptor to refresh the outer surface of the photoreceptor. However, if both the photoreceptor and the cleaning blade are hard, the shapes of both components will not conform well to the particles that accumulate at the contact point between them (i.e., toner particles and external additive particles that remain on the photoreceptor without being transferred), causing the particles (especially relatively small-sized external additive particles) to slip through the cleaning blade. These particles that slip through the cleaning blade cause streaky image defects. The image forming apparatus according to this embodiment ensures the durability of the cleaning blade by hardening the contact portion with the photoreceptor, while controlling the physical properties of the cleaning blade itself to be resilient to stress, thereby suppressing fluctuations in image density over a long period of time and making it less likely for streaky image defects to occur. The cleaning blade cleans the photoreceptor by bringing its high-hardness contact portion into contact with the outer surface of the photoreceptor. This suppresses filming of the outer surface of the photoreceptor and suppresses fluctuations in image density. Because the cleaning blade is highly resilient to stress, its shape easily follows the particles present on the outer surface of the photoreceptor, suppressing particle slippage, and as a result, making it less likely for streaky image defects to occur.

[0026] In this disclosure, the 100% modulus, rebound modulus, and tensile stress of the cleaning blade are values ​​measured using the contact member as a sample by the following measurement method.

[0027] The 100% modulus is determined in accordance with JIS K6251:2010, using a dumbbell-shaped No. 3 test specimen, at a temperature of 23°C and a tensile speed of 500 mm / min, and calculated from the stress at 100% strain. A Strograph AE Elastomer (Toyo Seiki Seisakusho Co., Ltd.) is used as the measuring device.

[0028] The rebound modulus is measured using a Lübke rebound modulus tester in an environment of 23°C, in accordance with JIS K6255:1996.

[0029] The tensile stress is the tensile stress at 200% strain measured at a temperature of 23°C. It is measured using a dumbbell-shaped specimen (Type 3) at a tensile speed of 500 mm / min. A Strograph AE Elastomer (Toyo Seiki Seisakusho Co., Ltd.) is used as the measuring device.

[0030] The configuration of the image forming apparatus according to this embodiment will be described in detail below.

[0031] The image forming apparatus according to this embodiment comprises a photoreceptor, a charging device, an electrostatic latent image forming device, a developing device, a transfer device, and a photoreceptor cleaning device. The image forming apparatus according to this embodiment may further include a fixing device for fixing the toner image transferred to the surface of the recording medium, and a static elimination device for irradiating the surface of the photoreceptor with static elimination light after the transfer of the toner image and before it becomes charged to remove static charge. In this embodiment, the part of the image forming apparatus that includes the photoreceptor may be a cartridge structure (process cartridge) that can be attached to and detached from the image forming apparatus.

[0032] The image forming apparatus according to this embodiment may be a direct transfer type image forming apparatus that directly transfers a toner image formed on the surface of a photoreceptor to a recording medium, or it may be an intermediate transfer type image forming apparatus that first transfers a toner image formed on the surface of a photoreceptor to the surface of an intermediate transfer body, and secondarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium. An intermediate transfer type transfer apparatus includes, for example, an intermediate transfer body on which a toner image is transferred, a primary transfer device that first transfers a toner image formed on the surface of a photoreceptor to the surface of the intermediate transfer body, and a secondary transfer device that secondarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of a recording medium.

[0033] The following is an example of an image forming apparatus according to this embodiment, but it is not limited to this example. The main parts shown in the figure will be described, and the descriptions of other parts will be omitted.

[0034] Figure 1 is a schematic diagram showing an example of an image forming apparatus according to this embodiment. As shown in Figure 1, the image forming apparatus 100 according to this embodiment includes a process cartridge 300 equipped with a photoreceptor 7, an exposure device 9 (an example of an electrostatic latent image forming apparatus), a transfer device 40 (a primary transfer device), and an intermediate transfer body 50. In the image forming apparatus 100, the exposure device 9 is positioned to expose the photoreceptor 7 from the opening of the process cartridge 300, and the transfer device 40 is positioned opposite the photoreceptor 7 via the intermediate transfer body 50, with a portion of the intermediate transfer body 50 in contact with the photoreceptor 7. Although not shown, the apparatus also includes a secondary transfer device that transfers the toner image transferred to the intermediate transfer body 50 to a recording medium (e.g., paper). The intermediate transfer body 50, the transfer device 40 (primary transfer device), and the secondary transfer device (not shown) are examples of transfer devices.

[0035] In Figure 1, the process cartridge 300 integrally supports a photoreceptor 7, a charging device 8 (an example of a charging device), a developing device 11 (an example of a developing device), and a cleaning device 13 (an example of a photoreceptor cleaning device) within a housing. The cleaning device 13 has a cleaning blade (an example of a cleaning member) 131, which is positioned to contact the surface of the photoreceptor 7.

[0036] Figure 1 shows an example of an image forming apparatus equipped with a fibrous member 132 (roll-shaped) for supplying lubricant 14 to the surface of the photoreceptor 7, and a fibrous member 133 (flat brush-shaped) for assisting cleaning. These can be arranged as needed.

[0037] Figure 2 is a schematic diagram showing another example of the image forming apparatus according to this embodiment. The image forming apparatus 120 shown in Figure 2 is a tandem-type multi-color image forming apparatus equipped with four process cartridges 300. In the image forming apparatus 120, the four process cartridges 300 are arranged in parallel on the intermediate transfer body 50, and one photoreceptor is used for each color. The image forming apparatus 120 has the same configuration as the image forming apparatus 100, except that it is a tandem type.

[0038] The following describes the various components of the image forming apparatus according to this embodiment.

[0039] [Photoreceptor] The photoreceptor 7 includes, for example, a conductive substrate, a photosensitive layer disposed on the conductive substrate, and a surface layer disposed on the photosensitive layer. The photosensitive layer may be a multilayer photosensitive layer consisting of a charge generation layer and a charge transport layer, or a single-layer photosensitive layer. Details of the photoreceptor will be described later.

[0040] [Charging device] As the charging device 8, for example, a contact-type charger using conductive or semiconductive charging rollers, charging brushes, charging films, charging rubber blades, charging tubes, etc., can be used. As the charging device 8, for example, non-contact roller chargers, known chargers such as scorotron chargers and corotron chargers that utilize corona discharge can also be used.

[0041] [Synthesis equipment] Examples of exposure devices 9 include optical equipment that exposes the surface of a photoreceptor 7 to a predetermined image using light such as semiconductor laser light, LED light, or liquid crystal shutter light. The wavelength of the light source is within the spectral sensitivity range of the photoreceptor. As for semiconductor lasers, near-infrared lasers with an oscillation wavelength of around 780 nm are the mainstream. However, the wavelength is not limited to this, and lasers with oscillation wavelengths in the 600 nm range or blue lasers with oscillation wavelengths between 400 nm and 450 nm may also be used. Furthermore, for color image formation, surface-emitting laser light sources capable of outputting multiple beams are also effective.

[0042] [Developing equipment] Examples of developing devices 11 include general developing devices that develop by contacting or not contacting the developing agent. There are no particular restrictions on the developing device 11 as long as it has the above-described functions, and it can be selected according to the purpose. For example, known developing devices that have the function of applying a one-component or two-component developing agent to the photoreceptor 7 using a brush, roller, etc. Among these, those that use a developing roller that holds the developing agent on its surface are preferred.

[0043] The developer used in the developing device 11 may be a one-component developer consisting of toner alone, or a two-component developer containing toner and a carrier. The developer may be magnetic or non-magnetic. Toner generally consists of toner particles and an external additive added to the toner particles.

[0044] [Photoconductor Cleaning Device] The cleaning device 13 uses a cleaning blade type device equipped with a cleaning blade 131. Details of the cleaning blade will be described later.

[0045] [Transfer device] Examples of the transfer device 40 include contact-type transfer chargers using belts, rollers, films, rubber blades, etc., and transfer chargers that are known themselves, such as scorotron transfer chargers and corotron transfer chargers that utilize corona discharge.

[0046] [Intermediate Transcript] As the intermediate transfer body 50, a belt-shaped material (intermediate transfer belt) containing semiconducting polyimide, polyamide-imide, polycarbonate, polyarylate, polyester, rubber, etc. is used. In addition to the belt shape, the intermediate transfer body may also be in the form of a drum.

[0047] The operation by which the image forming apparatus 100 shown in Figure 1 forms an image will be explained. The photoreceptor 7 rotates at a predetermined speed. The charging device 8 charges the surface of the photoreceptor 7. A laser beam, for example, is shone from the exposure device 9 onto the surface of the charged photoreceptor 7, and an electrostatic latent image is formed on the surface of the photoreceptor 7. The electrostatic latent image formed on the photoreceptor 7 moves to the development position as the photoreceptor 7 rotates. At the development position, the electrostatic latent image on the photoreceptor 7 is developed as a toner image by the developing device 11 and made visible. The toner image formed on the photoreceptor 7 moves to the primary transfer position as the photoreceptor 7 rotates. At the primary transfer position, a transfer bias is applied to the transfer device 40, and an electrostatic force from the photoreceptor 7 toward the transfer device 40 acts on the toner image on the photoreceptor 7, transferring the toner image to the intermediate transfer body 50. The intermediate transfer unit 50 moves at a predetermined speed, and at the secondary transfer position, the toner image is transferred to the recording medium by the secondary transfer device. Toner remaining on the surface of the photoreceptor 7 is removed and recovered by the cleaning device 13.

[0048] The photoreceptor included in the image forming apparatus according to this embodiment will be described in detail below. The cleaning blade of the photoreceptor cleaning device included in the image forming apparatus according to this embodiment will also be described in detail. Furthermore, the toner and developer used in the developing device included in the image forming apparatus according to this embodiment will be described in detail below.

[0049] [Photoreceptor] An embodiment of the photoreceptor will be described with reference to Figures 3 and 4.

[0050] Figure 3 is a schematic partial cross-sectional view showing an example of the layer structure of a photoreceptor. The photoreceptor 10A shown in Figure 3 has a structure in which a base layer 2, a charge generation layer 3, a charge transport layer 4, and a surface layer 6 are stacked in this order on a conductive substrate 1, with the charge generation layer 3 and the charge transport layer 4 constituting the photosensitive layer 5. In the photoreceptor 10A, the surface layer 6 is in contact with the charge transport layer 4. The photoreceptor 10A may have an intermediate layer (not shown) between the base layer 2 and the charge generation layer 3. The base layer 2 may or may not be present.

[0051] Figure 4 is a schematic partial cross-sectional view showing another example of the layer structure of a photoreceptor. The photoreceptor 10B shown in Figure 4 has a structure in which an undercoat layer 2, a single-layer photosensitive layer 5, and a surface layer 6 are stacked in this order on a conductive substrate 1. In the photoreceptor 10B, the surface layer 6 is in contact with the single-layer photosensitive layer 5. The photoreceptor 10B may have an intermediate layer (not shown) between the undercoat layer 2 and the charge generation layer 3. The undercoat layer 2 may or may not be present.

[0052] [Surface layer] The surface layer is provided on top of the photosensitive layer. The surface layer is the outermost layer of the photoreceptor.

[0053] From the viewpoint of increasing hardness and improving wear resistance, the surface layer preferably contains at least one type of filler particle selected from the group consisting of organic particles and inorganic particles.

[0054] Examples of organic particles include fluororesin particles, polystyrene resin particles, polymethyl methacrylate resin particles, and melamine resin particles. Examples of inorganic particles include metal oxide particles and silica particles. These particles may be used individually or in combination of two or more types.

[0055] The amount of filler particles contained in the surface layer is preferably 5% to 50% by mass, more preferably 8% to 40% by mass, and even more preferably 10% to 30% by mass, relative to the total mass of the surface layer, from the viewpoint of balancing the hardness to improve wear resistance with the electrical properties of the surface layer.

[0056] The surface layer preferably contains a charge transport material. Examples of charge transport materials for the surface layer include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, and triarylamine compounds.

[0057] From the viewpoint of increasing hardness and improving wear resistance, the surface layer is preferably a cured layer formed by the curing of a polymerizable composition or a reactive composition.

[0058] As an example of an embodiment of the surface layer, a layer formed by curing a composition containing monomers having polymerizable functional groups and fluororesin particles is cited. The monomers having polymerizable functional groups contained in the composition polymerize to form a cured layer.

[0059] Polymerization reactions of monomers having polymerizable functional groups include thermal polymerization, photopolymerization, and radiation polymerization. Examples of polymerizable functional groups in monomers are acrylic groups and methacrylic groups. Materials with charge transport capabilities may also be used as monomers with polymerizable functional groups. A polymerization initiator may be used depending on the type of monomer having polymerizable functional groups.

[0060] Examples of fluororesin particles include polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, and polychlorotrifluoroethylene. Fluororesin particles may be used individually or in combination of two or more types.

[0061] The average primary particle size of the fluororesin particles is preferably 100 nm to 300 nm, more preferably 120 nm to 280 nm, and even more preferably 150 nm to 250 nm.

[0062] The content of fluororesin particles in the surface layer is preferably 5% by mass or more and 50% by mass or less, more preferably 8% by mass or more and 40% by mass or less, and even more preferably 10% by mass or more and 30% by mass or less, based on the total mass of the surface layer.

[0063] Another example of a surface layer embodiment is a cured layer formed by curing a composition containing an ultraviolet-curable acrylic resin and at least one type of particle selected from the group consisting of metal oxide particles and silica particles. The ultraviolet-curable acrylic resin contained in the composition cures to form a cured layer.

[0064] Reactive functional groups found in UV-curable acrylic resins include acrylic groups and methacrylic groups. Acrylic resin acrylate is preferred as the UV-curable acrylic resin.

[0065] Examples of metal oxide particles include tin oxide, zinc oxide, aluminum oxide, titanium oxide, indium oxide, antimony oxide, and bismuth oxide. One type of metal oxide particle may be used alone, or two or more types may be used in combination.

[0066] The average primary particle size of the metal oxide particles and silica particles is preferably 0.1 μm or more and 2 μm or less, more preferably 0.2 μm or more and 1.5 μm or less, and even more preferably 0.3 μm or more and 1 μm or less.

[0067] The content of metal oxide particles and silica particles in the surface layer (total amount of these particles) is preferably 5% to 50% by mass, more preferably 8% to 40% by mass, and even more preferably 10% to 30% by mass, relative to the total mass of the surface layer.

[0068] A preferred method for forming the surface layer is to apply a polymerizable composition or a reactive composition onto the photosensitive layer, and then cure the polymerizable composition or reactive composition by heating or light irradiation. Conventional methods for applying polymerizable or reactive compositions onto a photosensitive layer include immersion coating, push-up coating, wire bar coating, spray coating, blade coating, air knife coating, and curtain coating.

[0069] The thickness of the surface layer is preferably 1 μm or more and 20 μm or less, more preferably 2 μm or more and 15 μm or less, and even more preferably 3 μm or more and 10 μm or less.

[0070] [Conductive substrate] Examples of conductive substrates include metal plates, metal drums, and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). Other examples of conductive substrates include paper, resin films, and belts coated, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.) or alloys. Here, "conductive" refers to a volume resistivity of 1 × 10⁻⁶. 13 This refers to a value less than Ω·cm.

[0071] When the photoreceptor is used in a laser printer, the surface of the conductive substrate is preferably roughened to a center-line average roughness Ra of 0.04 μm to 0.5 μm in order to suppress interference fringes that occur when irradiated with laser light. When non-interfering light is used as the light source, roughening to prevent interference fringes is not particularly necessary, but it is suitable for a longer lifespan because it suppresses the occurrence of defects due to irregularities on the surface of the conductive substrate.

[0072] Methods for roughening a surface include, for example, wet honing, which involves suspending an abrasive in water and spraying it onto a conductive substrate; centerless grinding, which involves pressing a conductive substrate against a rotating grinding wheel and continuously grinding it; and anodizing.

[0073] One method for roughening the surface is to disperse conductive or semiconductive powder in a resin without roughening the surface of the conductive substrate, to form a layer on the surface of the conductive substrate, and then roughen the surface with the particles dispersed in that layer.

[0074] Anodizing roughening treatment involves forming an oxide film on the surface of a conductive substrate (e.g., aluminum) by anodizing it in an electrolyte solution. Examples of electrolyte solutions include sulfuric acid solution and oxalic acid solution. However, the porous anodic oxide film formed by anodizing is chemically active, easily contaminated, and exhibits large resistance fluctuations depending on the environment. Therefore, it is preferable to perform a sealing treatment on the porous anodic oxide film to block the micropores of the oxide film by volume expansion due to a hydration reaction using pressurized steam or boiling water (metal salts such as nickel may be added), thereby converting it into a more stable hydrated oxide.

[0075] The thickness of the anodic oxide film is preferably, for example, 0.3 μm to 15 μm. When the film thickness is within this range, it tends to exhibit barrier properties against injection and tends to suppress the increase in residual potential due to repeated use.

[0076] The conductive substrate may be treated with an acidic treatment solution or with boehmite. Treatment with an acidic solution is carried out, for example, as follows: First, an acidic solution containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. The mixing ratio of phosphoric acid, chromic acid, and hydrofluoric acid in the acidic solution is, for example, in the range of 10% to 11% by mass for phosphoric acid, 3% to 5% by mass for chromic acid, and 0.5% to 2% by mass for hydrofluoric acid, and the total concentration of these acids is preferably in the range of 13.5% to 18% by mass. The treatment temperature is preferably, for example, 42°C to 48°C. The film thickness is preferably 0.3 μm to 15 μm.

[0077] The boehmite treatment is carried out, for example, by immersing the material in pure water at 90°C to 100°C for 5 to 60 minutes, or by contacting it with heated steam at 90°C to 120°C for 5 to 60 minutes. The film thickness is preferably 0.1 μm to 5 μm. This can be further treated with anodic oxidation using an electrolyte solution with low film solubility, such as adipic acid, boric acid, borate, phosphate, phthalate, maleate, benzoate, tartrate, or citrate.

[0078] [Sublayer] The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

[0079] As for inorganic particles, for example, powder resistance (volume resistivity) 1 × 10 2 Ω cm or more 1×10 11 Examples include inorganic particles with a size of Ω·cm or less. Among these, suitable inorganic particles having the above-mentioned resistance values ​​include metal oxide particles such as tin oxide particles, titanium oxide particles, zinc oxide particles, and zirconium oxide particles, with zinc oxide particles being particularly preferred.

[0080] The specific surface area of ​​inorganic particles using the BET method is, for example, 10 m². 2 A value of 1g or more is preferable. The volume-average particle size of the inorganic particles is preferably between 50 nm and 2000 nm (preferably between 60 nm and 1000 nm).

[0081] The inorganic particle content is preferably 10% by mass or more and 80% by mass or less relative to the binder resin, and more preferably 40% by mass or more and 80% by mass or less.

[0082] The inorganic particles may be surface-treated. Two or more types of inorganic particles with different surface treatments or particle sizes may be mixed and used.

[0083] Examples of surface treatment agents include silane coupling agents, titanate-based coupling agents, aluminum-based coupling agents, and surfactants. Silane coupling agents are particularly preferred, and silane coupling agents having an amino group are more preferred.

[0084] Examples of silane coupling agents having an amino group include, but are not limited to, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane.

[0085] Silane coupling agents may be used in combination of two or more types. For example, a silane coupling agent having an amino group may be used in combination with another silane coupling agent. Examples of other silane coupling agents include, but are not limited to, vinyltrimethoxysilane, 3-methacrylateoxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0086] The surface treatment method using the surface treatment agent may be any known method, and may be either a dry or wet method.

[0087] The amount of surface treatment agent applied is preferably, for example, 0.5% by mass or more and 10% by mass or less relative to the inorganic particles.

[0088] In this case, it is preferable for the underlayer to contain electron-accepting compounds (acceptor compounds) along with inorganic particles, from the viewpoint of improving the long-term stability of electrical properties and carrier blocking ability.

[0089] Examples of electron-accepting compounds include electron-transporting substances such as compounds having anthraquinone structures; quinone compounds such as chloranil and bromoanil; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone and 2,4,5,7-tetranitro-9-fluorenone; oxadiazole compounds such as 2-(4-biphenyl)-5-(4-t-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole, and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; diphenoquinone compounds such as 3,3',5,5'-tetra-t-butyldiphenoquinone; and benzophenone compounds. In particular, compounds having an anthraquinone structure are preferred as electron-accepting compounds. Examples of compounds having an anthraquinone structure include hydroxyanthraquinone compounds, aminoanthraquinone compounds, and aminohydroxyanthraquinone compounds. Specifically, examples of preferred compounds include anthraquinone, alizarin, quinizalin, anthralphine, purpurin, and their derivatives.

[0090] The electron-accepting compound may be dispersed in the underlayer together with inorganic particles, or it may be present attached to the surface of the inorganic particles.

[0091] Methods for attaching electron-accepting compounds to the surface of inorganic particles include, for example, dry methods or wet methods.

[0092] The dry method involves, for example, adding an electron-accepting compound, either directly or dissolved in an organic solvent, dropwise while stirring inorganic particles with a mixer that has a high shear force, or spraying it with dry air or nitrogen gas, to adhere the electron-accepting compound to the surface of the inorganic particles. When adding or spraying the electron-accepting compound, it is preferable to do so at a temperature below the boiling point of the solvent. After adding or spraying the electron-accepting compound, further baking at 100°C or higher may be performed. The baking temperature and time are not particularly limited as long as electrophotographic characteristics can be obtained.

[0093] The wet method involves dispersing inorganic particles in a solvent using, for example, a stirrer, ultrasonic disperser, sand mill, attritor, or ball mill, while adding an electron-accepting compound. After stirring or dispersion, the solvent is removed, and the electron-accepting compound adheres to the surface of the inorganic particles. Solvent removal methods include, for example, filtration or distillation. After solvent removal, further baking at 100°C or higher may be performed. The baking temperature and time are not particularly limited as long as electrophotographic characteristics can be obtained. In the wet method, the water content of the inorganic particles may be removed before adding the electron-accepting compound. Examples of this include removing water while stirring and heating in the solvent, or removing water by azeotrope with the solvent.

[0094] The electron-accepting compound may be applied before or after surface treatment with a surface treatment agent to the inorganic particles, or it may be applied simultaneously with the surface treatment with the surface treatment agent.

[0095] The content of the electron-accepting compound is preferably, for example, 0.01% by mass or more and 20% by mass or less relative to the inorganic particles, and more preferably 0.01% by mass or more and 10% by mass or less.

[0096] Examples of known polymer compounds used as the binder resin for the undercoat include acetal resin (e.g., polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, unsaturated polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, alkyd resin, epoxy resin, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. Examples of binder resins used in the undercoat include charge-transporting resins having charge-transporting groups, conductive resins (e.g., polyaniline), and the like.

[0097] Among these, a resin insoluble in the coating solvent of the upper layer is preferred as the binder resin used for the undercoat layer. In particular, a resin obtained by the reaction of a curing agent with at least one resin selected from the group consisting of thermosetting resins such as urea resin, phenol resin, phenol-formaldehyde resin, melamine resin, urethane resin, unsaturated polyester resin, alkyd resin, and epoxy resin is preferred. When using two or more of these binder resins in combination, the mixing ratio is set as needed.

[0098] The undercoat may contain various additives to improve electrical properties, environmental stability, and image quality. Examples of known additives include electron-transporting pigments such as polycyclic condensation and azo pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, titanium alkoxide compounds, organic titanium compounds, and silane coupling agents. As mentioned above, silane coupling agents are used for surface treatment of inorganic particles, but they may also be added to the undercoat as additives.

[0099] Examples of silane coupling agents used as additives include vinyltrimethoxysilane, 3-methacrylateoxypropyl-tris(2-methoxyethoxy)silane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, 3-mercaptopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, N,N-bis(2-hydroxyethyl)-3-aminopropyltriethoxysilane, and 3-chloropropyltrimethoxysilane.

[0100] Examples of zirconium chelate compounds include zirconium butoxide, ethyl zirconium acetate, zirconium triethanolamine, acetylacetonate zirconium butoxide, ethyl acetate zirconium butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octanoate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, methacrylate zirconium butoxide, stearate zirconium butoxide, and isostearate zirconium butoxide.

[0101] Examples of titanium chelate compounds include tetraisopropyl titanate, tetran-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, polytitanium acetylacetonate, titanium octylene glycolate, titanium lactate ammonium salt, titanium lactate, titanium lactate ethyl ester, titanium triethanolamine, and polyhydroxytitanium stearate.

[0102] Examples of aluminum chelating compounds include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, and aluminum tris(ethylacetoacetate).

[0103] These additives may be used individually or as a mixture or polycondensate of multiple compounds.

[0104] The underlayer should ideally have a Vickers hardness of 35 or higher. The surface roughness (ten-point average roughness) of the undercoat layer should be adjusted to between 1 / (4n) (where n is the refractive index of the upper layer) and 1 / 2 of the exposure laser wavelength λ used, in order to suppress moiré patterns. Resin particles may be added to the undercoat to adjust the surface roughness. Examples of resin particles include silicone resin particles and cross-linked polymethyl methacrylate resin particles. The surface of the undercoat may also be polished to adjust the surface roughness. Polishing methods include buffing, sandblasting, wet honing, and grinding.

[0105] The formation of the undercoat is not particularly limited, and known formation methods can be used. For example, it can be carried out by forming a coating film of an undercoat-forming solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary.

[0106] Solvents for preparing the coating solution for forming the undercoat include known organic solvents such as alcohol-based solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone-based solvents, ketone alcohol-based solvents, ether-based solvents, and ester-based solvents. Specific examples of these solvents include common organic solvents such as methanol, ethanol, n-propanol, iso-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene.

[0107] Known methods for dispersing inorganic particles when preparing a coating solution for forming an undercoat include, for example, roll mills, ball mills, vibrating ball mills, attritors, sand mills, colloid mills, and paint shakers.

[0108] Conventional methods for applying the undercoating solution onto a conductive substrate include, for example, the blade coating method, wire bar coating method, spray coating method, immersion coating method, bead coating method, air knife coating method, and curtain coating method.

[0109] The thickness of the undercoat layer is preferably set to a range of 15 μm or more, and more preferably 20 μm to 50 μm.

[0110] [Middle class] An intermediate layer may be further provided between the undercoat layer and the photosensitive layer. The intermediate layer is, for example, a layer containing a resin. Examples of resins used in the intermediate layer include polymer compounds such as acetal resin (e.g., polyvinyl butyral), polyvinyl alcohol resin, polyvinyl acetal resin, casein resin, polyamide resin, cellulose resin, gelatin, polyurethane resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinyl acetate resin, vinyl chloride-vinyl acetate-maleic anhydride resin, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, and melamine resin. The intermediate layer may contain an organometallic compound. Examples of organometallic compounds used in the intermediate layer include those containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon. The compounds used in these intermediate layers may be used individually, as a mixture of multiple compounds, or as polycondensates.

[0111] Among these, the intermediate layer is preferably a layer containing an organometallic compound that contains zirconium atoms or silicon atoms.

[0112] The formation of the intermediate layer is not particularly limited, and known formation methods can be used. For example, it can be carried out by forming a coating film of an intermediate layer-forming coating solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary. Conventional methods such as immersion coating, push-up coating, wire bar coating, spray coating, blade coating, air knife coating, and curtain coating are used to form the intermediate layer.

[0113] The thickness of the intermediate layer is preferably set to a range of 0.1 μm to 3 μm, for example. The intermediate layer may also be used as a base layer.

[0114] [Charge generation layer] The charge generation layer is, for example, a layer containing a charge generation material and a binder resin. Alternatively, the charge generation layer may be a vapor-deposited layer of the charge generation material. A vapor-deposited layer of the charge generation material is suitable when using non-coherent light sources such as LEDs (Light Emitting Diodes) or organic EL (Electro-Luminescence) image arrays.

[0115] Examples of charge-generating materials include azo pigments such as bisazo and trisazo; fused aromatic pigments such as dibromoanthonthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0116] Among these, in order to accommodate laser exposure in the near-infrared region, it is preferable to use a metallic phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge generating material. Specifically, for example, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, titanyl phthalocyanine, etc. are more preferable.

[0117] On the other hand, to accommodate laser exposure in the near-ultraviolet region, preferred charge-generating materials include fused aromatic pigments such as dibromoanthonthrone, thioindigo-based pigments, porphyrazine compounds, zinc oxide, trigonal selenium, and bisazo pigments.

[0118] The above charge generating material may also be used when using non-coherent light sources such as LEDs and organic EL image arrays, which have a central emission wavelength between 450 nm and 780 nm.

[0119] When n-type semiconductors such as fused aromatic pigments, perylene pigments, and azo pigments are used as charge-generating materials, dark currents are less likely to be generated, and image defects called black spots can be suppressed even in thin films. The n-type is determined using the commonly used time-of-flight method, which is determined by the polarity of the photocurrent that flows, and materials that readily carry electrons as carriers rather than holes are classified as n-type.

[0120] The binder resin used in the charge generation layer can be selected from a wide range of insulating resins, or it may be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane. Examples of binder resins include polyvinyl butyral resin, polyarylate resin (such as polycondensates of bisphenols and aromatic divalent carboxylic acids), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinylpyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, and polyvinylpyrrolidone resin. Here, "insulating properties" refer to a volume resistivity of 1 × 10⁻⁶. 13 This refers to a value of Ω·cm or greater. These binder resins can be used individually or in combination of two or more types.

[0121] The mixing ratio of the charge-generating material to the binder resin is preferably within the range of 10:1 to 1:10 by mass ratio.

[0122] The charge generation layer may also contain other known additives.

[0123] The formation of the charge generation layer is not particularly limited, and known formation methods can be used. For example, it can be carried out by forming a coating film of a coating solution for forming a charge generation layer by adding the above components to a solvent, drying the coating film, and heating it as necessary. The charge generation layer may also be formed by vapor deposition of a charge generation material. Formation of the charge generation layer by vapor deposition is particularly suitable when using fused ring aromatic pigments or perylene pigments as the charge generation material.

[0124] Solvents for preparing the coating solution for forming the charge generation layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene. These solvents may be used individually or in mixtures of two or more.

[0125] Methods for dispersing particles (e.g., charge-generating materials) in a coating solution for forming a charge-generating layer include, for example, media dispersers such as ball mills, vibrating ball mills, attritors, sand mills, and horizontal sand mills, as well as media-less dispersers such as stirrers, ultrasonic dispersers, roll mills, and high-pressure homogenizers. Examples of high-pressure homogenizers include collision methods, which disperse the dispersion by causing liquid-liquid collisions or liquid-wall collisions under high pressure, and penetration methods, which disperse the dispersion by penetrating fine channels under high pressure. During this dispersion, it is effective to set the average particle size of the charge-generating material in the coating solution for forming the charge-generating layer to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

[0126] Conventional methods for applying the charge-generating layer forming coating solution onto the undercoat (or intermediate layer) include, for example, the blade coating method, wire bar coating method, spray coating method, immersion coating method, bead coating method, air knife coating method, and curtain coating method.

[0127] The thickness of the charge generation layer is preferably set to a range of 0.1 μm to 5.0 μm, more preferably 0.2 μm to 2.0 μm.

[0128] [Charge transport layer] The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may also be a layer containing a polymer charge transport material.

[0129] Examples of the charge transport material include quinone compounds such as p-benzoquinone, chloranil, bromanil, and anthraquinone; tetracyanoquinodimethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanovinyl compounds; and electron-transporting compounds such as ethylene compounds. Examples of the charge transport material also include hole-transporting compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These charge transport materials may be used alone or in combination of two or more, but are not limited thereto.

[0130] From the viewpoint of charge mobility, as the charge transport material, a triarylamine derivative represented by the following structural formula (a-1) and a benzidine derivative represented by the following structural formula (a-2) are preferable.

[0131] [Chemical formula]

[0132] In the structural formula (a-1), Ar T1 , Ar T2 , and Ar T3 each independently represent a substituted or unsubstituted aryl group, -C6H4-C(R T4 )=C(R T5 )(R T6 ), or -C6H4-CH=CH-CH=C(R T7 )(R T8 ). R T4 , R T5 , R T6 , R T7 , and R T8 each independently represent a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Substituents for each of the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Furthermore, substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms are also examples of substituents for each of the above groups.

[0133] [ka]

[0134] In structural formula (a-2), R T91 and R T92 Each of these independently represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. T101 , R T102 , R T111 and R T112 Each of these independently consists of a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, an amino group substituted with an alkyl group having 1 to 2 carbon atoms, a substituted or unsubstituted aryl group, and -C(R T12 )=C(R T13 )(R T14 ), or -CH=CH-CH=C(R T15 )(R T16 ) shows R T12 , R T13 , R T14 , R T15 and R T16 Each of these independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. Tm1, Tm2, ​​Tn1, and Tn2 each independently represent an integer between 0 and 2. Substituents for each of the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Furthermore, substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms are also examples of substituents for each of the above groups.

[0135] Among the triarylamine derivatives represented by structural formula (a-1) and the benzidine derivatives represented by structural formula (a-2), in particular, "-C6H4-CH=CH-CH=C(R T7 )(RT8 Triarylamine derivatives having ")" and "-CH=CH-CH=C(R T15 )(R T16 A benzidine derivative having ) is preferred from the viewpoint of charge mobility.

[0136] As polymer charge transport materials, known charge transport materials such as poly-N-vinylcarbazole and polysilane can be used. Polyester-based polymer charge transport materials are particularly preferred. Polymer charge transport materials may be used alone or in combination with a binder resin.

[0137] Examples of binder resins used in the charge transport layer include polycarbonate resin, polyester resin, polyarylate resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinylcarbazole, and polysilane. Among these, polycarbonate resin or polyarylate resin is preferred as the binder resin. These binder resins can be used individually or in combination of two or more. The preferred mixing ratio of the charge transport material to the binder resin is between 10:1 and 1:5 by mass.

[0138] The charge transport layer may also contain other known additives.

[0139] Known formation methods can be applied to form the charge transport layer. For example, a coating film of a charge transport layer forming solution is formed by adding a material to a solvent, the coating film is dried, and the charge transport layer is formed by heating as needed.

[0140] Examples of solvents for preparing coating solutions for charge transport layer formation include organic solvents such as aromatic hydrocarbons like benzene, toluene, xylene, and chlorobenzene; ketones like acetone and 2-butanone; halogenated aliphatic hydrocarbons like methylene chloride, chloroform, and ethylene chloride; and cyclic or linear ethers like tetrahydrofuran and ethyl ether. These solvents may be used individually or in mixtures of two or more.

[0141] When applying a coating solution for forming a charge transport layer onto a charge generating layer, possible coating methods include blade coating, wire bar coating, spray coating, immersion coating, bead coating, air knife coating, and curtain coating.

[0142] The thickness of the charge transport layer is set, for example, preferably within the range of 5 μm to 50 μm, and more preferably within the range of 10 μm to 30 μm.

[0143] [Single-layer photosensitive layer] A single-layer photosensitive layer is, for example, a layer comprising a charge generating material, a charge transporting material, and optionally a binder resin and other additives. These materials are the same as those described for the charge generating layer and the charge transporting layer.

[0144] The charge-generating material content in the single-layer photosensitive layer is preferably 0.1% to 10% by mass, and more preferably 0.8% to 5% by mass, relative to the total solid content. The charge transport material content in the single-layer photosensitive layer should be between 5% and 50% by mass relative to the total solid content.

[0145] The method for forming a single-layer photosensitive layer is the same as the method for forming a charge generation layer or a charge transport layer.

[0146] The thickness of the single-layer photosensitive layer is, for example, preferably 5 μm to 50 μm, and more preferably 10 μm to 40 μm.

[0147] [Cleaning Blade] The cleaning blade contains polyurethane rubber, which is polymerized from at least a polyol component and a polyisocyanate component, in at least the contact portion (hereinafter referred to as the "contact portion") that comes into contact with the photoreceptor, or the component constituting the contact portion (hereinafter referred to as the "contact component"). The cleaning blade has at least a contact portion or contact member with a ratio of 0.25 or more between the 100% modulus M100 (MPa) and the rebound modulus Re (%), a rebound modulus Re of less than 25%, and a tensile stress of 15 MPa or more at 200% strain at a temperature of 23°C.

[0148] A cleaning blade that satisfies the above characteristics has a high M100 / Re ratio, a low rebound modulus, and high tensile stress, thereby reducing pressure fluctuations (i.e., maximum pressure) in the blade, improving the blade's energy absorption capacity, and stabilizing the blade's behavior.

[0149] The ratio M100 / Re of the contact portion or contact member is 0.25 or higher, preferably 0.28 or higher, and more preferably 0.3 or higher. From the viewpoint of wear resistance, the upper limit of the ratio M100 / Re of the contact portion or contact member is preferably 1.0 or lower, and more preferably 0.9 or lower. The ratio M100 / Re of the contact portion or contact member is preferably 0.25 or higher and 1.0 or lower, more preferably 0.28 or higher and 1.0 or lower, and even more preferably 0.3 or higher and 0.9 or lower.

[0150] The rebound modulus Re of the contact portion or contact member is less than 25%, preferably 22% or less, and more preferably 20% or less. The lower limit of the rebound modulus Re of the contact portion or contact member is preferably 10% or more, and more preferably 13% or more, from the viewpoint of suppressing blade noise and wear resistance. The rebound modulus Re of the contact portion or contact member is preferably 10% or more and less than 25%, more preferably 10% or more and 22%, and even more preferably 13% or more and 20%.

[0151] From the viewpoint of satisfying the above characteristics, the 100% modulus M100 of the contact portion or contact member is preferably 4 MPa to 10 MPa, and more preferably 5 MPa to 9 MPa.

[0152] The tensile stress at 200% strain at a temperature of 23°C for the contact portion or contact member is 15 MPa or more, preferably 21 MPa or more, and more preferably 26 MPa or more. The upper limit of the tensile stress of the contact portion or contact member is preferably 40 MPa or less, and more preferably 35 MPa or less. The tensile stress of the contact portion or contact member is preferably 15 MPa or more and 40 MPa or less, more preferably 21 MPa or more and 40 MPa or less, and even more preferably 26 MPa or more and 35 MPa or less.

[0153] The 100% modulus, rebound modulus, and tensile stress of the contact area or contact member can be controlled by adjusting the ratio of hard segments to soft segments contained in the polyurethane rubber, depending on the type and amount of each polymerization component of the polyurethane rubber and the manufacturing conditions.

[0154] The materials and composition of the contact portion or contact member are described below. The number-average molecular weight of polyurethane rubber components is a value measured by gel permeation chromatography (GPC).

[0155] • Polyurethane rubber Polyurethane rubber is a polyurethane rubber obtained by polymerizing at least a polyol component and a polyisocyanate component. The polyurethane rubber may also be a polyurethane rubber obtained by further polymerizing a resin having functional groups that react with isocyanate groups, if necessary.

[0156] • Polyol components Polyol components include high molecular weight polyols and low molecular weight polyols.

[0157] High molecular weight polyols are polyols with a number average molecular weight of 500 or more (preferably 500 to 5000). Known polyols include polyester polyols obtained by dehydration condensation of low molecular weight polyols and dibasic acids; polycarbonate polyols obtained by reaction of low molecular weight polyols and alkyl carbonates; polycaprolactone polyols, polyether polyols, etc. Commercially available high molecular weight polyols include, for example, Plaxel 205 and Plaxel 240 from Daicel Corporation. High molecular weight polyols may be used individually or in combination of two or more types.

[0158] The polymerization ratio of the polymer polyol is preferably 30 mol% to 50 mol% relative to the total polymerization components of the polyurethane rubber, and more preferably 40 mol% to 50 mol%.

[0159] Low molecular weight polyols are polyols with a number-average molecular weight of less than 500. Low molecular weight polyols are materials that function as chain length extenders and crosslinking agents.

[0160] 1,4-butanediol is a suitable low molecular weight polyol. The proportion of 1,4-butanediol is preferably more than 50 mol% and 75 mol% or less, more preferably 52 mol% to 75 mol%, even more preferably 55 mol% to 75 mol%, and even more preferably 55 mol% to 60 mol% or less, relative to the total polyol components. The proportion of 1,4-butanediol relative to the total low molecular weight polyol is preferably 80 mol% or more, more preferably 90 mol% or more, and even more preferably 100 mol%. It is most preferable that the entire low molecular weight polyol is 1,4-butanediol.

[0161] In addition to 1,4-butanediol, other low molecular weight polyols include diols (bifunctional), triols (trifunctional), and tetraols (tetrafunctional), which are known as chain length extenders and crosslinking agents. These polyols other than 1,4-butanediol may be used individually or in combination of two or more.

[0162] The polymerization ratio of the low molecular weight polyol is preferably between 50 mol% and 75 mol% relative to the total polymerization components of the polyurethane rubber, more preferably between 52 mol% and 75 mol%, more preferably between 55 mol% and 75 mol%, and even more preferably between 55 mol% and 60 mol%.

[0163] • Polyisocyanate components Examples of polyisocyanate components include 4,4'-diphenylmethane diisocyanate (MDI), 2,6-toluene diisocyanate (TDI), 1,6-hexane diisocyanate (HDI), 1,5-naphthalene diisocyanate (NDI), and 3,3-dimethylbiphenyl-4,4-diisocyanate (TODI). One polyisocyanate component may be used alone, or two or more may be used in combination. Preferred polyisocyanate components include 4,4'-diphenylmethane diisocyanate (MDI), 1,5-naphthalene diisocyanate (NDI), and hexamethylene diisocyanate (HDI).

[0164] The polymerization ratio of the polyisocyanate component is preferably 5 mol% to 25 mol%, and more preferably 10 mol% to 20 mol%, relative to the total polymerization components of the polyurethane rubber. Setting the polymerization ratio of the polyisocyanate component within this range makes it easier to set the 100% modulus, rebound modulus, and tensile stress within the aforementioned ranges.

[0165] • Resins having functional groups that react with isocyanate groups (functional group-containing resins) As functional group-containing resins, flexible resins are preferred, and aliphatic resins having a linear structure are preferred. Specific examples of functional group-containing resins include acrylic resins containing two or more hydroxyl groups, polybutadiene resins containing two or more hydroxyl groups, and epoxy resins having two or more epoxy groups.

[0166] Examples of commercially available acrylic resins containing two or more hydroxyl groups include Actflow UMB-2005B, UMB-2005P, UMB-2005, UME-2005, etc. (Sohken Chemical Co., Ltd.). Examples of commercially available polybutadiene resins containing two or more hydroxyl groups include R-45HT (Idemitsu Kosan Co., Ltd.).

[0167] As an epoxy resin having two or more epoxy groups, an epoxy resin that is more flexible and tougher than general epoxy resins is preferred. For example, an epoxy resin having a flexible skeleton in its main chain structure is preferred, and examples of flexible skeletons include alkylene skeletons, cycloalkane skeletons, and polyoxyalkylene skeletons, with polyoxyalkylene skeletons being particularly preferred. Furthermore, an epoxy resin with low viscosity relative to its molecular weight is preferred. Specifically, a weight-average molecular weight is preferably in the range of 900 ± 100, and a viscosity at 25°C is preferably in the range of 15000 ± 5000 mPa·s, and more preferably in the range of 15000 ± 3000 mPa·s. An example of a commercially available epoxy resin having these characteristics is EPLICON EXA-4850-150 (DIC Corporation).

[0168] • Crosslinking density of polyurethane rubber The crosslinking density of polyurethane rubber is 0.93 × 10⁻¹⁰, from the viewpoint of controlling the 100% modulus, rebound modulus, and tensile stress within the aforementioned ranges. -3 mol / m 3 The above 1.45 × 10 -3 mol / m 3 The following is preferable: 1.01 × 10 -3 mol / m 3 The above is 1.26 × 10 -3 mol / m 3 The following is more preferable: 1.07 × 10 -3 mol / m 3 The above is 1.22 × 10 -3 mol / m 3 The following is even more preferable.

[0169] The crosslinking density of polyurethane rubber is calculated using the following formula. Formula:n=E' / 3RT n: Crosslink density (mol / m 3 ) E': Storage modulus in the flat region (dyne / cm²) 2 ) R: Gas constant (8.31 J / K·mol = N·m / K·mol = 10 7 dyne·cm / k·mol) T: Absolute temperature (K) of the parallel (storage) modulus of elasticity 1 Pa = 9.8 (dyne / cm²) 2 )

[0170] The storage modulus is a property derived from dynamic viscoelasticity. When a sinusoidal strain τ, represented by τ = τ₀eiωt, is applied to a viscoelastic material in a steady-state oscillation manner, the stress σ is expressed as σ = σ₀ei(ωt + δ). If the dynamic modulus, i.e., the complex modulus, is E*, then E* = σ / τ = σ₀ / τ₀·cosδ + i·σ₀ / τ₀·sinδ = E' + iE''. E' is the storage modulus, E'' is the loss modulus, and the loss tangent tanδ = E'' / E'. Dynamic viscoelastic properties are measured using a dynamic viscoelasticity measuring instrument. The storage modulus is measured at 1 Hz using the EXSTAR6000 thermal analysis system (Seiko Instruments Inc.).

[0171] • Polyurethane rubber segment The polyurethane rubber preferably has hard segments and soft segments. The average diameter of the aggregates of the hard segments is preferably 1 μm or more and 10 μm or less, and more preferably 1 μm or more and 5 μm or less.

[0172] The average diameter of the hard segment aggregates is measured by the following method. Using a polarizing microscope (BX51-P, Olympus Corporation), images were captured at 20x magnification and then binarized through image processing. The equivalent circle diameter of 500 aggregates (5 points per cleaning blade, 5 aggregates per point) was measured using 20 cleaning blades, and the arithmetic mean of these 500 equivalent circle diameters was calculated. Image binarization was performed using the image processing software OLYMPUS Stream essentials (Olympus Corporation), adjusting the hue / saturation / luminance thresholds so that crystalline and hard segment aggregates appeared black and amorphous parts (corresponding to soft segments) appeared white.

[0173] • Weight-average molecular weight of polyurethane rubber The weight-average molecular weight of polyurethane rubber is preferably between 1000 and 4000, and more preferably between 1500 and 3500.

[0174] • Method for manufacturing polyurethane rubber and cleaning blades For the manufacture of polyurethane rubber, general manufacturing methods such as the prepolymer method and the one-shot method may be applied. The polyurethane rubber composition is formed into a sheet by centrifugal molding, extrusion molding, etc., and then the cleaning blade is manufactured by cutting or other processing.

[0175] Examples of catalysts used in the manufacture of polyurethane rubber include amine compounds such as tertiary amines, quaternary ammonium salts, and organometallic compounds such as organotin compounds. A single catalyst may be used, or two or more catalysts may be used in combination.

[0176] Examples of tertiary amines include trialkylamines such as triethylamine; tetraalkyldiamines such as N,N,N',N'-tetramethyl-1,3-butanediamine; amino alcohols such as dimethylethanolamine; esteramines such as ethoxylated amines, ethoxylated diamines, bis(diethylethanolamine) adipate, cyclohexylamine derivatives such as triethylenediamine (TEDA) and N,N-dimethylcyclohexylamine; morpholine derivatives such as N-methylmorpholine and N-(2-hydroxypropyl)-dimethylmorpholine; and piperazine derivatives such as N,N'-diethyl-2-methylpiperazine and N,N'-bis-(2-hydroxypropyl)-2-methylpiperazine. Examples of quaternary ammonium salts include 2-hydroxypropyltrimethylammonium octylate, 1,5-diazabicyclo[4.3.0]nonene-5(DBN)octylate, 1,8-diazabicyclo[5.4.0]undecene-7(DBU)octylate, DBU oleate, DBU-p-toluenesulfonate, DBU formate, and 2-hydroxypropyltrimethylammonium formate. Examples of organotin compounds include dialkyltin compounds such as dibutyltin dilaurate and dibutyltin di(2-ethylhexoate); stannous 2-ethylcaproate and stannous oleate. From the viewpoint of hydrolysis resistance, the tertiary ammonium salt triethylenediamine (TEDA) is preferred, and from the viewpoint of processability, the quaternary ammonium salt is preferred. Among the quaternary ammonium salts, 1,5-diazabicyclo[4.3.0]nonene-5(DBN)·octylate, 1,8-diazabicyclo[5.4.0]undecene-7(DBU)-octylate, and DBU-formate are preferably used due to their high reaction activity.

[0177] The amount of catalyst added is preferably in the range of 0.0005% by mass or more and 0.03% by mass or less of the total polyurethane rubber constituting the contact member, and particularly preferably 0.001% by mass or more and 0.01% by mass or less.

[0178] Figure 5 shows an example of a cleaning blade embodiment. The tip of the cleaning blade 22A shown in Figure 5 is facing in a direction opposite to the rotation direction (arrow direction) of the photoreceptor 12, and in this state is in contact with the surface of the photoreceptor 12.

[0179] The angle θ between the cleaning blade 22A and the photoreceptor 12 is preferably 5° to 35°, and more preferably 10° to 25°. The angle θ refers to the angle between the tangent line at the contact point between the tip of the cleaning blade 22A and the photoreceptor 12 (the dashed line in Figure 5) and the non-deformable portion of the cleaning blade 22A. The pressure N applied by the cleaning blade 22A to the photoreceptor 12 is 0.6 gf / mm². 2 The above 6.0 gf / mm 2 The following is preferable. The pressing pressure N is the pressure (gf / mm²) applied when the cleaning blade 22A contacts the photoreceptor 12 and presses toward the center of the photoreceptor 12. 2 )

[0180] The cleaning blade 22A is supported by a support member (not shown in Figure 3) attached to the side of the blade opposite to the side that contacts the photoreceptor 12. The cleaning blade 22A is pressed against the photoreceptor 12 by the force from the support member. Examples of support members include metal members such as aluminum and stainless steel. An adhesive layer may be present between the support member and the cleaning blade 22A.

[0181] The cleaning blade 22A has a contact portion that comes into contact with the photoreceptor 12, and this contact portion is made of a material containing polyurethane rubber polymerized from at least a polyol component and a polyisocyanate component. The cleaning blade 22A has a ratio of 0.25 or higher for the ratio of 100% modulus M100 (MPa) to rebound modulus Re (%) at least at the contact area, a rebound modulus Re of less than 25%, and a tensile stress of 15 MPa or higher at 23°C and 200% strain. [Examples]

[0182] This embodiment will be described in detail below with reference to examples, but this embodiment is not limited to these examples. In the following description, unless otherwise specified, "parts" and "%" are all based on mass. In the following description, synthesis, processing, manufacturing, testing, etc., were carried out at room temperature (25℃±3℃) unless otherwise specified.

[0183] <Manufacturing of cleaning blades> A urethane rubber sheet material was poured into a mold to form a urethane rubber sheet, i.e., a cleaning blade. The 100% modulus, rebound modulus, and tensile stress of the urethane rubber sheet were controlled by the type and composition of the material. Table 1 shows the physical properties of the urethane rubber sheet.

[0184] [Table 1]

[0185] <Manufacturing of photoreceptors> [Photoconductor (A-1)] -Formation of the lower layer- Zinc oxide (average particle size 70 nm, specific surface area 15 m²) 2 100 parts of (Teika Co., Ltd.) were mixed with 500 parts of toluene and stirred. 1.3 parts of a silane coupling agent (product name: KBM603, Shin-Etsu Chemical Co., Ltd., N-2-(aminoethyl)-3-aminopropyltrimethoxysilane) were added and the mixture was stirred for 2 hours. Then, the toluene was removed by distillation under reduced pressure, and the mixture was baked at 120°C for 3 hours to obtain zinc oxide surface-treated with the silane coupling agent.

[0186] 110 parts of surface-treated zinc oxide was mixed with 500 parts of tetrahydrofuran by stirring, and a solution of 0.6 parts of alizarin dissolved in 50 parts of tetrahydrofuran was added. The mixture was stirred at 50°C for 5 hours. The solids were then filtered off by vacuum filtration, and the mixture was dried under reduced pressure at 60°C to obtain alizarin-treated zinc oxide.

[0187] 100 parts of a solution prepared by dissolving 60 parts alizarin-modified zinc oxide, 13.5 parts curing agent (blocked isocyanate, trade name: Sumijule 3175, Sumitomo Bayer Urethane Co., Ltd.), and 15 parts butyral resin (trade name: Esrec BM-1, Sekisui Chemical Co., Ltd.) in 68 parts methyl ethyl ketone was mixed with 5 parts methyl ethyl ketone, and the mixture was dispersed for 2 hours using 1 mm diameter glass beads in a sand mill to obtain a dispersion. To the dispersion, 0.005 parts dioctyl tin dilaurate as a catalyst and 4 parts silicone resin particles (trade name: Tospar 145, Momentive Performance Materials, Inc.) were added to obtain a coating solution for forming the undercoat layer.

[0188] A coating solution for forming the undercoat was applied to the outer surface of a conductive substrate (aluminum cylindrical tube with an outer diameter of 30 mm, a length of 250 mm, and a wall thickness of 1 mm) by immersion coating. Drying and curing was performed at 170°C for 40 minutes to form an undercoat layer with a thickness of 20 μm.

[0189] -Formation of a charge generation layer- A mixture consisting of 15 parts of hydroxygallium phthalocyanine (having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3° in its X-ray diffraction spectrum using CuKα characteristic X-rays), 10 parts of vinyl chloride / vinyl acetate copolymer resin (product name: VMCH, Nippon Unicar Co., Ltd.) as a binder resin, and 200 parts of n-butyl acetate was dispersed for 4 hours using glass beads with a diameter of 1 mm in a sand mill. 175 parts of n-butyl acetate and 180 parts of methyl ethyl ketone were added to the dispersion and stirred to obtain a coating solution for forming the charge generation layer. The coating solution for forming the charge generation layer was immersed and coated onto the undercoat, and dried at room temperature to form a charge generation layer with a thickness of 0.25 μm.

[0190] -Formation of a charge transport layer- ·Charge transport material: CTM-1 ··· 40 parts • Polyarylate resin: PA1 ··· 42 parts • Polycarbonate resin: PC1... 18 parts • Solvent: Tetrahydrofuran • 270 units • Solvent: Toluene • 30 copies The above materials were stirred and mixed to obtain a coating solution for forming a charge transport layer. The coating solution for forming a charge transport layer was applied to the charge generating layer by immersion, and dried at 150°C for 30 minutes to form a charge transport layer with a thickness of 30 μm. The chemical structures of CTM-1, PA1, and PC1 are as follows.

[0191] [ka]

[0192] -Formation of the surface layer- Sixty parts of polytetrafluoroethylene particles (Lubron L-2, Daikin Industries, Ltd.), three parts of fluorine atom-containing resin (GF300, Toagosei Co., Ltd.), and 140 parts of cyclopentanol were mixed and dispersed using an ultra-high-speed disperser to prepare a dispersion. 21 parts of compound (1-1), 49 parts of compound (2-15), and 1 part of polymerization initiator (OTAZO-15, Otsuka Chemical Co., Ltd.) were dissolved in 80 parts of cyclopentanol and mixed with 100 parts of the dispersion to prepare a coating solution. The coating solution was immersed on a charge transport layer, air-dried at room temperature for 30 minutes, and then heated at 150°C for 45 minutes under a nitrogen atmosphere with an oxygen concentration of 200 ppm to cure, forming a surface layer with a thickness of 15 μm. Thus, photoreceptor (A-1) was obtained. The chemical structures of compounds (1-1) and (2-15) are as follows.

[0193] [ka]

[0194] [Photoconductor (A-2)~(A-4)] Each photoreceptor was manufactured in the same manner as the photoreceptor (A-1), except that the surface layer specifications were changed as shown in Table 2.

[0195] [Photoreceptor (B-1)] The undercoat layer and charge transport layer were formed on the conductive substrate in the same manner as in the manufacture of the photoreceptor (A-1). The following surface layers were formed on the charge transport layer.

[0196] -Formation of the surface layer- • Radical polymerizable monomers that do not possess charge transport function (Caprolactone-modified dipentaerythritol hexaacrylate, KAYARAD DPCA-120, Nippon Kayaku Co., Ltd.) ...10 copies • Compound (6): Radical polymerizable compound with charge transport function...7 parts • Compound (7): Diamine compound ···0.07 part Compound (8): Oxazole compound ···0.21 part • Alumina particles (AA05, Sumitomo Chemical Co., Ltd.) ... 1.7 parts • Photopolymerization initiator (1-hydroxycyclohexylphenyl ketone) (Irgacure 184, BASF Japan Ltd.) ... 0.85 parts Tetrahydrofuran ···100 copies The above materials were mixed to prepare a coating solution. The coating solution was applied to the charge transport layer by spray coating under a nitrogen stream, and left in the nitrogen stream for 10 minutes to allow it to dry to the touch. The chemical structures of compounds (6), (7), and (8) are as follows.

[0197] [ka]

[0198] Next, ultraviolet irradiation was performed under the following conditions in an ultraviolet light irradiation booth where the oxygen concentration was replaced with nitrogen gas until it was below 2%. • Metal halide lamp: 160W / cm² ·Irradiation distance: 120mm ·Irradiation intensity: 700mW / cm 2 • Irradiation time: 60 seconds Next, the material was dried at 130°C for 20 minutes to form a surface layer with a thickness of 5 μm. In this way, photoreceptor (B-1) was obtained.

[0199] [Photoconductor (B-2) to (B-4)] Each photoconductor was manufactured in the same manner as the manufacture of the photoconductor (B-1), except that the specifications of the surface layer were changed as shown in Table 3.

[0200] [Photoconductor (C-1)] In the same manner as the manufacture of the photoconductor (A-1), a subbing layer to a charge transport layer was formed on a conductive substrate. The following surface layer was formed on the charge transport layer.

[0201] - Formation of surface layer - 200 parts of silica particles (number average primary particle diameter 20 nm), 10 parts of an electron transporting compound ETM101, and 1500 parts of 2-butanol were stirred and mixed, and using a circulation type ultrasonic homogenizer (RUS-600TCVP, Nippon Seiki Co., Ltd., 19.5 kHz, 600 W), they were dispersed at a temperature of 35°C and a circulation flow rate of 40 L / H for 0.5 hours. Next, it was passed through a filter with a pore diameter of 1 μm, and 2-butanol was removed by vacuum distillation. The obtained dried product was heated at 120°C for 2 hours to bake the electron transporting compound onto the particles. Next, it was pulverized with a pin mill to obtain inorganic particles (A) surface-treated with the electron transporting compound. The chemical structure of ETM101 is as follows.

[0202] [Chemical formula]

[0203] · Inorganic particles (A) ··· 68 parts · Compound M1: Radical polymerizable monomer ··· 100 parts · Polymerization initiator: Irgacure819 (BASF Japan Ltd.) ··· 10 parts · 2-butanol ··· 230 parts · Tetrahydrofuran ··· 12 parts The above materials were mixed and stirred to prepare a coating solution. The coating solution was applied onto the charge transport layer using a circular slide hopper coater. Ultraviolet light was irradiated for 1 minute at an illuminance of 16 mW / cm 2 and then dried at a temperature of 80 °C for 70 minutes to form a surface layer with a layer thickness of 3 μm. Thus, a photoreceptor (C-1) was obtained. The chemical structure of Compound M1 is as follows. R in the formula is an alkyl group.

[0204] [Chemical formula]

[0205] [Photoreceptors (C-2) to (C-4)] In the same manner as the production of the photoreceptor (C-1), each photoreceptor was produced, except that the specifications of the surface layer were changed as shown in Table 4.

[0206] <Manufacture of an image forming apparatus> An electrophotographic image forming apparatus Apeos C2060 (Fuji Film Business Innovation Co., Ltd.) was prepared, and a photoreceptor and a cleaning blade were mounted in the combinations as described in Tables 2 to 4. Using the image forming apparatus, in an environment of a temperature of 25 °C and a relative humidity of 50%, a halftone image with a density of 50% for half of the image forming range on A4 ordinary paper and a halftone image with a density of 30% for the other half were continuously output 100,000 sheets.

[0207] <Performance evaluation> [Suppression of image density variation] Using a reflection densitometer X-Rite404 (X-Rite), in the halftone images with a density of 30% at the 100th, 10,000th, and 100,000th sheets, three L * values, a * values, and b * values were measured. Based on the following formula, the color difference ΔE between the 100th and 10,oooth sheets and the color difference ΔE between the 100th and 100,000th sheets were calculated, and the color difference ΔE was classified as follows. The results are shown in Tables 2 to 4.

[0208]

Number

[0209] In the formula, L1, a1, and b1 are the L * value, a * value, and b * value (average values at three locations respectively), and L2, a2, and b2 are the L * value, a * value, and b * value (average values at three locations respectively) of the 10,000th or 100,000th image.

[0210] A: Color difference ΔE is 1 or less B: Color difference ΔE is greater than 1 and 5 or less C: Color difference ΔE is greater than 5

[0211] [Linear image defect] The 10 images from the 91st to the 100th were visually observed, and the degree of linear image defects was classified as follows. The results are shown in Tables 2 to 4.

[0212] A: In all 10 images, no linear image defects are observed in either the 50% density image or the 30% density image. B: In all 10 images, no linear image defects are observed in the 50% density image. In 1 to 5 images, slight linear image defects are observed in the 30% density image. C: Slight linear image defects are observed in both the 50% density image and the 30% density image.

[0213]

Table 2

[0214]

Table 3

[0215]

Table 4

[0216] The image forming apparatus of this disclosure includes the following embodiments.

[0217] (Note) (((1))) A photoreceptor having a surface layer with a transmittance of 5% or more and 95% or less for light with a wavelength of 1000 nm, A charging device for charging the surface of the photoreceptor, An electrostatic latent image forming apparatus for forming an electrostatic latent image on the surface of the charged photoreceptor, A developing apparatus that develops an electrostatic latent image formed on the surface of a photoreceptor using a developer containing toner to form a toner image, A transfer device for transferring the toner image onto the surface of a recording medium, A photoreceptor cleaning device having a cleaning blade that contacts the surface of the photoreceptor, for cleaning the surface of the photoreceptor, The contact portion of the cleaning blade that contacts the photoreceptor contains polyurethane rubber polymerized from at least a polyol component and a polyisocyanate component, the ratio of 100% modulus M100 (MPa) to rebound modulus Re (%) M100 / Re is 0.25 or more, the rebound modulus Re is less than 25%, and the tensile stress at 200% strain at a temperature of 23°C is 15 MPa or more. Image forming apparatus. (((2))) The image forming apparatus according to (((1))), wherein the ratio M100 / Re is 0.28 or more and 1.0 or less. (((3))) The image forming apparatus according to either (((1))) or (((2))), wherein the cleaning blade is a laminate of polyurethane rubber. (((4))) The image forming apparatus according to any one of (((1))) to (((3))), wherein the surface layer of the photoreceptor contains at least one filler particle selected from the group consisting of organic particles and inorganic particles. (((5))) The image forming apparatus according to any one of (((1))) to (((4))), wherein the surface layer of the photoreceptor is a layer obtained by curing a composition containing monomers having polymerizable functional groups and fluororesin particles. (((6))) The image forming apparatus according to any one of (((1))) to (((4))), wherein the surface layer of the photoreceptor is a layer formed by curing a composition containing an ultraviolet-curable acrylic resin and at least one particle selected from the group consisting of metal oxide particles and silica particles.

[0218] According to (((1))), (((3))), (((4))), (((5))) or (((6))), an image forming apparatus is provided that is less prone to producing streaky image defects compared to an image forming apparatus in which the ratio M100 / Re is less than 0.25, the rebound modulus Re is 25% or more, or the tensile stress is less than 15 MPa. According to (((2))), an image forming apparatus is provided that is less prone to producing streaky image defects compared to an image forming apparatus in which the ratio M100 / Re is less than 0.28 or greater than 1.0. [Explanation of symbols]

[0219] 7 Photoreceptor, 8 Charging device, 9 Exposure device, 11 Developing device, 13 Cleaning device, 14 Lubricant, 40 Transfer device, 50 Intermediate transfer body, 100 Image forming device, 120 Image forming device, 131 Cleaning blade, 132 Fibrous material (roll type), 133 Fibrous material (flat brush type), 300 Process cartridge

[0220] 1 Conductive substrate, 2 Undercoat layer, 3 Charge generation layer, 4 Charge transport layer, 5 Photosensitive layer, 6 Surface layer, 10A photoreceptor, 10B photoreceptor

[0221] 12 Photoconductor, 22A Cleaning Blade

Claims

1. A photoreceptor having a surface layer with a transmittance of 5% or more and 95% or less for light with a wavelength of 1000 nm, A charging device for charging the surface of the photoreceptor, An electrostatic latent image forming apparatus for forming an electrostatic latent image on the surface of the charged photoreceptor, A developing apparatus that develops an electrostatic latent image formed on the surface of a photoreceptor using a developer containing toner to form a toner image, A transfer device for transferring the toner image onto the surface of a recording medium, A photoreceptor cleaning device having a cleaning blade that contacts the surface of the photoreceptor, for cleaning the surface of the photoreceptor, The contact portion of the cleaning blade that contacts the photoreceptor contains polyurethane rubber polymerized from at least a polyol component and a polyisocyanate component, the ratio of 100% modulus M100 (MPa) to rebound modulus Re (%) M100 / Re is 0.25 or more, the rebound modulus Re is less than 25%, and the tensile stress at 200% strain at a temperature of 23°C is 15 MPa or more. Image forming apparatus.

2. The image forming apparatus according to claim 1, wherein the ratio M100 / Re is 0.28 or more and 1.0 or less.

3. The image forming apparatus according to claim 1, wherein the cleaning blade is a laminate of polyurethane rubber.

4. The image forming apparatus according to claim 1, wherein the surface layer of the photoreceptor contains at least one filler particle selected from the group consisting of organic particles and inorganic particles.

5. The image forming apparatus according to any one of claims 1 to 4, wherein the surface layer of the photoreceptor is a layer formed by curing a composition containing a monomer having polymerizable functional groups and fluororesin particles.

6. The image forming apparatus according to any one of claims 1 to 4, wherein the surface layer of the photoreceptor is a layer formed by curing a composition containing an ultraviolet-curable acrylic resin and at least one particle selected from the group consisting of metal oxide particles and silica particles.

Images