Image forming apparatus and process cartridge

Abstract

To provide an image forming apparatus that prevents wear of an electrophotographic photoreceptor and prevents a reduction in image quality due to poor cleaning.SOLUTION: An image forming apparatus comprises: an electrophotographic photoreceptor that has a photosensitive layer and a surface protective layer in this order; electrifying means that electrifies a surface of the electrophotographic photoreceptor; electrostatic charge image forming means that forms an electrostatic charge image on the electrified surface of the electrophotographic photoreceptor; developing means that stores electrostatic charge image developer including toner for electrostatic charge image development, and develops the electrostatic charge image formed on the surface of the electrophotographic photoreceptor with the electrostatic charge image developer as a toner image; transfer means that transfers the toner image formed on the surface of the electrophotographic photoreceptor to a surface of a recording medium; and cleaning means having a cleaning blade that comes into contact with the surface of the electrophotographic photoreceptor and cleans the surface of the electrophotographic photoreceptor. An coefficient μ of static friction of the surface protective layer in the electrophotographic photoreceptor is 0.3 or less, and a difference Δ in amount of strain between a stationary period and an operation period of the cleaning blade is 100 μST or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an image forming apparatus and a process cartridge. [Background technology]

[0002] Patent Document 1 discloses an electrophotographic apparatus that develops a toner image on a photoreceptor, transfers the toner image onto a transfer body to form an image, and cleans residual toner on the photoreceptor with a cleaning blade, characterized in that the coefficient of friction between the photoreceptor and the cleaning blade is 1.0 or less, the angle between the cleaning blade and the photoreceptor is 18° or more, and the amount of penetration of the cleaning blade into the photoreceptor is 0.7 mm or more.

[0003] Patent Document 2 discloses an image forming apparatus comprising: an electrophotographic photoreceptor having, in this order, a substrate, a photosensitive layer, and a protective layer containing oxygen and gallium, having a first region on the outer peripheral surface side and a second region closer to the substrate than the first region, having a larger atomic ratio [oxygen / gallium] than the first region; a charging means for charging the surface of the electrophotographic photoreceptor; a latent image forming means for exposing the surface of the electrophotographic photoreceptor charged by the charging means to form an electrostatic latent image; a developing means for developing the electrostatic latent image formed on the electrophotographic photoreceptor with a developer containing toner to form a toner image; a transfer means for transferring the toner image formed on the electrophotographic photoreceptor to a recording medium; and a cleaning means for cleaning the surface of the electrophotographic photoreceptor, having a cleaning blade with a contact load of 1.0 gf / mm or more and 4.0 gf / mm or less, a contact angle of 6 degrees or more and 14 degrees or less, and a penetration amount of 0.5 mm or more and 2.5 mm or less. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 08-286510

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] The problem of the embodiment of the present disclosure is to provide an image forming apparatus that includes an electrophotographic photoreceptor having a surface protective layer, charging means, electrostatic charge image forming means, developing means, transfer means, and cleaning means having a cleaning blade, and suppresses wear of the electrophotographic photoreceptor and deterioration of image quality due to poor cleaning as compared with a case where the coefficient of static friction μ of the surface protective layer in the electrophotographic photoreceptor exceeds 0.3 or the difference Δ in the amount of strain between when the cleaning blade is stationary and when it is operating exceeds 100 μST.

Means for Solving the Problems

[0006] The above problems are solved by the following present invention. That is,

[0007] <1> An electrophotographic photoreceptor having a photosensitive layer and a surface protective layer in this order on a conductive support, Charging means for charging the surface of the electrophotographic photoreceptor, Electrostatic charge image forming means for forming an electrostatic charge image on the charged surface of the electrophotographic photoreceptor, Developing means for accommodating an electrostatic charge developer containing toner for developing an electrostatic charge image and developing the electrostatic charge image formed on the surface of the electrophotographic photoreceptor as a toner image with the electrostatic charge developer, Transfer means for transferring the toner image formed on the surface of the electrophotographic photoreceptor to the surface of a recording medium, Cleaning means having a cleaning blade that contacts the surface of the electrophotographic photoreceptor and cleans the surface of the electrophotographic photoreceptor, Comprising, An image forming apparatus in which the coefficient of static friction μ of the surface protective layer in the electrophotographic photoreceptor is 0.3 or less and the difference Δ in the amount of strain between when the cleaning blade is stationary and when it is operating is 100 μST or less.

[0008] <2> The aforementioned surface protective layer is a metal oxide layer containing a Group 13 element and oxygen. <1> The image forming apparatus described above. <3> The metal oxide layer containing the group 13 element and oxygen is a metal oxide layer containing gallium oxide. <2> The image forming apparatus described above. <4> The surface roughness Ra of the metal oxide layer is 1 nm or more and 5 nm or less. <3> The image forming apparatus described above. <5> When the cleaning blade is brought into contact with the surface of the electrophotographic photoreceptor, the contact angle WA is 8° or more and 14° or less, and the penetration depth is 0.8 mm or more and 1.2 mm. <1> ~ <4> An image forming apparatus as described in any one of the following. <6> The difference Δ in the amount of strain is 65 μST or more and 90 μST or less. <5> The image forming apparatus described above.

[0009] <7> An electrophotographic photoreceptor having a photosensitive layer and a surface protective layer in that order on a conductive support, A cleaning means having a cleaning blade that contacts the surface of the electrophotographic photoreceptor and cleans the surface of the electrophotographic photoreceptor, Equipped with, A process cartridge for attachment to and detachment from an image forming apparatus, wherein the static friction coefficient μ of the surface protective layer in the electrophotographic photoreceptor is 0.3 or less, and the difference Δ of the amount of strain between the stationary and operating states of the cleaning blade is 100 μST or less. [Effects of the Invention]

[0010] <1> , <2> , <3> , or <5> According to the present invention, an image forming apparatus is provided that includes an electrophotographic photoreceptor having a surface protective layer, a charging means, an electrostatic image forming means, a developing means, a transfer means, and a cleaning means having a cleaning blade, which suppresses wear of the electrophotographic photoreceptor and suppresses deterioration of image quality due to poor cleaning compared to cases where the static friction coefficient μ of the surface protective layer of the electrophotographic photoreceptor is greater than 0.3, or where the difference Δ of the amount of strain between the stationary and operating states of the cleaning blade is greater than 100 μST. <4> According to the invention, an image forming apparatus is provided that suppresses wear of the electrophotographic photoreceptor and suppresses deterioration of image quality due to poor cleaning, compared to the case where the surface roughness Ra of the metal oxide layer is less than 1 nm. <6> According to the invention, an image forming apparatus is provided that suppresses wear of the electrophotographic photoreceptor and suppresses deterioration of image quality due to poor cleaning, compared to cases where the difference in strain amount Δ is less than 65 μST or greater than 90 μST. <7> According to the present invention, a process cartridge is provided that includes an electrophotographic photoreceptor having a surface protective layer and a cleaning means having a cleaning blade, and that suppresses wear of the electrophotographic photoreceptor and suppresses deterioration of image quality due to poor cleaning compared to a case where the static friction coefficient μ of the surface protective layer of the electrophotographic photoreceptor is greater than 0.3, or the difference Δ of the amount of strain between the stationary and operating states of the cleaning blade is greater than 100 μST. [Brief explanation of the drawing]

[0011] [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 cross-sectional view showing an example of the layer configuration of an electrophotographic photoreceptor in an image forming apparatus according to this embodiment. [Figure 3] This is a schematic cross-sectional view showing another example of the layer configuration of the electrophotographic photoreceptor included in the image forming apparatus according to this embodiment. [Figure 4] This is a schematic diagram showing an example of a film deposition apparatus used for forming a metal oxide layer on an electrophotographic photoreceptor. [Figure 5] This is a schematic diagram illustrating an example of a plasma generator used for forming the metal oxide layer in electrophotographic photoreceptors. [Figure 6] This is an enlarged view showing the position where the cleaning blade and the photoreceptor come into contact in the image forming apparatus shown in Figure 1. [Modes for carrying out the invention]

[0012] The embodiments of this disclosure are described below. These descriptions and embodiments are illustrative and do not limit the scope of the embodiments.

[0013] 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.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] <Image forming apparatus> The image forming apparatus according to this embodiment comprises: an electrophotographic photoreceptor having a photosensitive layer and a surface protective layer in that order on a conductive support; charging means for charging the surface of the electrophotographic photoreceptor; electrostatic image forming means for forming an electrostatic image on the charged surface of the electrophotographic photoreceptor; developing means containing an electrostatic image developer including an electrostatic image developing toner, and developing the electrostatic image formed on the surface of the electrophotographic photoreceptor as a toner image using the electrostatic image developer; transfer means for transferring the toner image formed on the surface of the electrophotographic photoreceptor to the surface of a recording medium; and cleaning means having a cleaning blade that contacts the surface of the electrophotographic photoreceptor and cleans the surface of the electrophotographic photoreceptor, wherein the static friction coefficient μ of the surface protective layer on the electrophotographic photoreceptor is 0.3 or less, and the difference Δ of the amount of strain between the stationary and operating states of the cleaning blade is 100 μST or less.

[0018] In the image forming apparatus according to this embodiment, the electrophotographic photoreceptor is also simply referred to as the "photoreceptor," the electrostatic image developing toner is also simply referred to as the "toner," and the electrostatic image developing agent is also simply referred to as the "developer."

[0019] To improve the cleaning performance of the photoreceptor surface, one method involves pressing the cleaning blade, a cleaning component, firmly against the surface of the photoreceptor. However, this method increases the stress on the surface of the photoreceptor, which can cause wear on the photoreceptor, and the cleaning blade may become significantly warped and partially chipped. If the cleaning blade chips, the toner remaining on the surface of the photoreceptor can slip through, causing image defects and potentially leading to a decrease in image quality.

[0020] The image forming apparatus according to this embodiment includes an electrophotographic photoreceptor having a surface protective layer, a charging means, an electrostatic image forming means, a developing means, a transfer means, and a cleaning means having a cleaning blade. Furthermore, the static friction coefficient μ of the surface protective layer of the electrophotographic photoreceptor is 0.3 or less, and the difference Δ of strain between the stationary and operating states of the cleaning blade is 100 μST or less. Thus, by examining the relationship between the surface of the photoreceptor and the cleaning blade, we found that by keeping the static friction coefficient μ of the surface protective layer and the difference Δ in the amount of strain between the stationary and operating states of the cleaning blade below the above-mentioned values, wear on the electrophotographic photoreceptor can be suppressed, and the deterioration of image quality due to poor cleaning can be suppressed. The reason for this can be inferred as follows: The fact that the static friction coefficient μ of the surface protective layer of the photoreceptor is 0.3 or less indicates that the surface of the surface protective layer has a slippery property. A cleaning blade is brought into contact with the surface of such a photoreceptor to clean it, and in the image forming apparatus according to this embodiment, the difference Δ of the strain amount between the stationary and operating states of the cleaning blade is set to 100 μST. With this configuration, it is presumed that the cleaning blade can continue to contact the photoreceptor without flapping. As a result, the image forming apparatus according to this embodiment can suppress wear of the electrophotographic photoreceptor and suppress the deterioration of image quality due to poor cleaning.

[0021] - Static friction coefficient μ - The static friction coefficient μ of the surface protective layer on the photoreceptor should be 0.30 or less. However, the lower limit of the static friction coefficient μ of the surface protective layer is preferably 0.2 or more, for example, from the viewpoint of adhesion between the photoreceptor and the cleaning blade. The static friction coefficient μ is measured using a friction and wear testing machine (for example, HEIDON Tribogear TYPE-14, manufactured by Shinto Kagaku Co., Ltd.) with a sapphire needle.

[0022] -Difference in strain amount Δ- The difference in strain Δ between the stationary and operating states of the cleaning blade should be 100 μST or less, and from the viewpoint of further suppressing wear of the electrophotographic photoreceptor, it is preferably 95 μST or less, and more preferably 90 μST or less. Furthermore, from the viewpoint of further suppressing the deterioration of image quality due to poor cleaning, the difference in strain Δ between the stationary and operating states of the cleaning blade should be 50 μST or more, and more preferably 65 μST or more. Based on the above, the difference Δ in strain between the stationary and operating states of the cleaning blade is preferably 50 μST to 95 μST, and more preferably 65 μST to 90 μST. By keeping the difference Δ in strain within this range, wear of the electrophotographic photoreceptor can be further suppressed, and the deterioration of image quality due to poor cleaning can be further suppressed.

[0023] The difference in strain amount Δ is calculated as follows. A strain gauge (KFG-02, manufactured by Kyowa Dengyo) is attached with adhesive 1 mm from the tip of the side of the cleaning blade that contracts when in contact with the photoreceptor. The lead wires of the strain gauge are connected to a strain data acquisition unit (NR-ST04, manufactured by Keyence), and this unit is connected to a computer via a data logger (NR-500, manufactured by Keyence). The attached strain gauge detects the amount of strain on the cleaning blade as an electrical signal. After installing the cleaning blade with a strain gauge attached into the process cartridge and assembling it into the image forming apparatus, wait at least 10 minutes to stabilize the baseline. Record the amount of strain when the baseline is stabilized (this will be called static strain A), then print a 50% halftone image on A3 size paper and record the amount of strain of the cleaning blade during printing and while the photoreceptor is operating (this will be called operating strain B). Here, when the cleaning blade is brought into contact with the surface of the photoreceptor, the contact angle WA shall be within the range of 8° to 14°, and the penetration depth shall be within the range of 0.5 mm to 1.2 mm. The obtained static strain A and operating strain B are introduced into the following equation to calculate the difference in strain Δ. The difference in strain amount Δ = (Strain amount A at rest) - (Strain amount B during operation)

[0024] The configuration of the image forming apparatus according to this embodiment will be described in detail below.

[0025] The image forming apparatus according to this embodiment comprises: an electrophotographic photoreceptor having a photosensitive layer and a surface protective layer in that order on a conductive support; charging means for charging the surface of the electrophotographic photoreceptor; electrostatic image forming means for forming an electrostatic image on the charged surface of the electrophotographic photoreceptor; developing means containing an electrostatic image developer including an electrostatic image developing toner, and developing the electrostatic image formed on the surface of the electrophotographic photoreceptor as a toner image with the electrostatic image developer; transfer means for transferring the toner image formed on the surface of the electrophotographic photoreceptor to the surface of a recording medium; and cleaning means having a cleaning blade that contacts the surface of the electrophotographic photoreceptor and cleans the surface of the electrophotographic photoreceptor. The recording medium may further include fixing means for fixing the toner image transferred to its surface.

[0026] Here, the image forming apparatus according to this embodiment may be a well-known image forming apparatus such as a direct transfer apparatus that directly transfers a toner image formed on the surface of a photoreceptor to a recording medium; an intermediate transfer 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; or an apparatus equipped with a static elimination device that irradiates the surface of the photoreceptor with static elimination light to eliminate static charge after the transfer of the toner image and before charging. In the case of an intermediate transfer method apparatus, the transfer apparatus may be configured to include, for example, an intermediate transfer body on which a toner image is transferred; a primary transfer apparatus that first transfers the toner image formed on the surface of the photoreceptor to the surface of the intermediate transfer body; and a secondary transfer apparatus that secondarily transfers the toner image transferred to the surface of the intermediate transfer body to the surface of the recording medium.

[0027] In the image forming apparatus according to this embodiment, the portion including at least a photoreceptor may constitute a unit for the image forming apparatus and may be a cartridge structure (process cartridge) that can be attached to and detached from the image forming apparatus. Herein, the process cartridge according to this embodiment comprises an electrophotographic photoreceptor having a photosensitive layer and a surface protective layer in that order on a conductive support, and a cleaning means having a cleaning blade that contacts the surface of the electrophotographic photoreceptor and cleans the surface of the electrophotographic photoreceptor, wherein the static friction coefficient μ of the surface protective layer on the electrophotographic photoreceptor is 0.3 or less, and the difference Δ of the amount of strain between the stationary and operating states of the cleaning blade is 100 μST or less, and the process cartridge is detachable from an image forming apparatus. The process cartridge according to this embodiment is not limited to the above configuration comprising an electrophotographic photoreceptor and cleaning means, but may also include, as necessary, at least one selected from other means such as a charging means, an electrostatic image forming means, a developing means, and a transfer means.

[0028] 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 other parts will be omitted from the explanation.

[0029] Figure 1 is a schematic diagram showing an example of an image forming apparatus according to this embodiment. The image forming apparatus 10 according to this embodiment includes a photoreceptor 12, as shown in Figure 1. The photoreceptor 12 is cylindrical and connected to a drive unit 27 such as a motor via a drive force transmission member (not shown) such as a gear, and is rotationally driven by the drive unit 27 around a rotation axis indicated by a black dot. In the example shown in Figure 1, the photoreceptor 12 is rotationally driven in the direction of arrow A.

[0030] Around the photoreceptor 12, for example, a charging device 15 (an example of a charging means), an electrostatic image forming device 16 (an example of an electrostatic image forming means), a developing device 18 (an example of a developing means), a transfer device 31 (an example of a transfer means), a cleaning device 22 (an example of a cleaning means), and a static elimination device 24 are arranged in order along the rotational direction of the photoreceptor 12. The image forming apparatus 10 also includes a fixing device 26 having a fixing member 26A and a pressurizing member 26B positioned in contact with the fixing member 26A. The image forming apparatus 10 also has a control device 36 that controls the operation of each device (each part). The unit including the photoreceptor 12, charging device 15, electrostatic image forming device 16, developing device 18, transfer device 31, and cleaning device 22 corresponds to the image forming unit.

[0031] In the image forming apparatus 10, at least the photoreceptor 12 may be provided as a process cartridge integrated with other devices.

[0032] [Electrophotographic photoconductor] The photoreceptor has a photosensitive layer and a surface protective layer on a conductive support, in that order. The static friction coefficient μ of the surface protective layer is 0.3 or less. Furthermore, the photosensitive layer in an electrophotographic photoreceptor may be a single-layer photoreceptor that integrates the functions of a charge generating material and a charge transport material by containing them in the same photoreceptor layer, or it may be a multilayer photoreceptor with separate functions having a charge generating layer and a charge transport layer. When the photosensitive layer is a multilayer photoreceptor, the order of the charge generating layer and the charge transport layer is not particularly limited, but it is preferable that the photoreceptor has a configuration on a conductive support in which the charge generating layer and the charge transport layer are in this order. In addition, the photoreceptor may also contain layers other than these layers.

[0033] Figure 2 is a schematic cross-sectional view showing an example of the layer configuration of a photoreceptor in an image forming apparatus according to this embodiment. The photoreceptor 107A has a structure in which an undercoat layer 101 is provided on a conductive support 104, and on top of that, a charge generation layer 102, a charge transport layer 103, and a surface protection layer 106 are arranged in this order. In the photoreceptor 107A, a photosensitive layer 105 is configured in which the functions of the charge generation layer 102 and the charge transport layer 103 are separated. Figure 3 is a schematic cross-sectional view showing another example of the layer configuration of the photoreceptor in the image forming apparatus according to this embodiment. The photoreceptor 107B has a structure in which an undercoat layer 101 is provided on a conductive support 104, and a photosensitive layer 105 and a surface protective layer 106 are provided on top of it in that order. In the photoreceptor 107B, a single-layer photosensitive layer is constructed in which a charge generating material and a charge transporting material are contained in the same photosensitive layer 105 and their functions are integrated.

[0034] In this embodiment, the photoreceptor may or may not have an undercoat layer 101.

[0035] The details of the photoreceptor in this embodiment will be described below, but reference numerals will be omitted.

[0036] (Conductive support) Examples of conductive supports 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 supports 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 10⁻¹⁰. 13 This refers to a value less than Ωcm.

[0037] When an electrophotographic photoreceptor is used in a laser printer, the surface of the conductive support 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. While roughening to prevent interference fringes is not particularly necessary when using non-interfering light as the light source, it is beneficial for extending the lifespan of the conductive support by suppressing the occurrence of defects due to surface irregularities.

[0038] Methods for roughening a surface include, for example, wet honing, which involves suspending an abrasive in water and spraying it onto a support; centerless grinding, which involves pressing a conductive support against a rotating grinding wheel and continuously grinding it; and anodizing.

[0039] One method for roughening the surface is to disperse conductive or semiconductive powder in a resin without roughening the surface of the conductive support, to form a layer on the surface of the conductive support, and then roughen the surface with the particles dispersed in that layer.

[0040] Anodizing roughening treatment involves forming an oxide film on the surface of a conductive support by using a metal (e.g., aluminum) conductive support as the anode and anodic oxidizing 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.

[0041] 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.

[0042] The conductive support 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.

[0043] 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.

[0044] (subbing layer) The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

[0045] As for inorganic particles, for example, powder resistance (volume resistivity) 10 2 Ωcm or more 10 11 Examples include inorganic particles smaller than Ωcm. 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.

[0046] 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).

[0047] 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.

[0048] 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.

[0049] 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.

[0050] 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.

[0051] 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.

[0052] The surface treatment method using the surface treatment agent may be any known method, and may be either a dry or wet method.

[0053] 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.

[0054] 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.

[0055] Examples of electron-accepting compounds include quinone compounds such as chloranil and bromonil; 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; and diphenoquinone compounds such as 3,3',5,5'-tetra-t-butyldiphenoquinone; as well as other electron-transporting substances. 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, and specifically, for example, anthraquinone, alizarin, quinizalin, anthralphine, and purpurin are preferred.

[0056] 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.

[0057] Methods for attaching electron-accepting compounds to the surface of inorganic particles include, for example, dry methods or wet methods.

[0058] 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.

[0059] The wet method involves dispersing inorganic particles in a solvent using methods such as stirring, ultrasound, sand milling, attritoring, and ball milling, while adding an electron-accepting compound. After stirring or dispersion, the solvent is removed to adhere the electron-accepting compound 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.

[0060] Furthermore, the attachment of the electron-accepting compound may be performed before or after surface treatment with a surface treatment agent on the inorganic particles, or it may be performed simultaneously with the attachment of the electron-accepting compound and surface treatment with the surface treatment agent.

[0061] 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.

[0062] 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.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] Examples of aluminum chelating compounds include aluminum isopropylate, monobutoxyaluminum diisopropylate, aluminum butyrate, diethylacetoacetate aluminum diisopropylate, and aluminum tris(ethylacetoacetate).

[0069] These additives may be used individually or as a mixture or polycondensate of multiple compounds.

[0070] 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.

[0071] There are no particular restrictions on the formation of the undercoat layer, and well-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.

[0072] 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 cellsolve, ethyl cellsolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene, and toluene.

[0073] 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.

[0074] Conventional methods for applying the undercoating solution onto a conductive support 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.

[0075] 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.

[0076] (Middle class) Although not shown in the diagram, 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.

[0077] Among these, the intermediate layer is preferably a layer containing an organometallic compound that contains zirconium atoms or silicon atoms.

[0078] There are no particular restrictions on the formation of the intermediate layer, and well-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, knife coating, and curtain coating are used to form the intermediate layer.

[0079] 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.

[0080] (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.

[0081] 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.

[0082] Among these, in order to accommodate laser exposure in the near-infrared region, it is preferable to use a metal phthalocyanine pigment or a metal-free phthalocyanine pigment as the charge generating material. Specifically, for example, hydroxygallium phthalocyanine; chlorogallium phthalocyanine; dichlorotin phthalocyanine; and titanyl phthalocyanine are more preferable.

[0083] On the other hand, to accommodate laser exposure in the near-ultraviolet region, preferred charge-generating materials include fused aromatic pigments such as dibromoanthoten; thioindigo pigments; porphyrazine compounds; zinc oxide; trigonal selenium; and bisazo pigments.

[0084] Even when using non-coherent light sources such as LEDs and organic EL image arrays with a central emission wavelength between 450 nm and 780 nm, the above charge generating materials may be used. However, from the viewpoint of resolution, when using a thin film of 20 μm or less for the photosensitive layer, the electric field strength in the photosensitive layer becomes high, making it easier for charge reduction due to charge injection from the substrate to occur, resulting in image defects known as black spots. This is particularly noticeable when using charge generating materials that are p-type semiconductors that easily generate dark current, such as trigonal selenium and phthalocyanine pigments.

[0085] In contrast, 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 occur, and image defects called black spots can be suppressed even in thin films. The determination of whether a device is n-type is made using the commonly used time-of-flight method, based on the polarity of the photocurrent flowing through it. Devices that are more likely to carry electrons as carriers than holes are classified as n-type.

[0086] 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 (polycondensate of bisphenols and aromatic divalent carboxylic acids, etc.), 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" refers to a volume resistivity of 10 13 This refers to a value of Ωcm or greater. These binder resins can be used individually or in combination of two or more types.

[0087] Furthermore, 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.

[0088] The charge generation layer may also contain other well-known additives.

[0089] The formation of the charge generation layer is not particularly limited, and well-known formation methods can be used. For example, it can be carried out by forming a coating film of a charge generation layer forming solution obtained 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 the charge generation material. Formation of the charge generation layer by vapor deposition is particularly suitable when using fused aromatic pigments or perylene pigments as the charge generation material.

[0090] Solvents for preparing the coating solution for forming the charge generation layer include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellsolve, ethyl cellsolve, 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.

[0091] 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. Furthermore, 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.

[0092] 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.

[0093] The film thickness of the charge generation layer is, for example, preferably set within the range of 0.1 μm or more and 5.0 μm or less, more preferably 0.2 μm or more and 2.0 μm or less.

[0094] (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 be a layer containing a polymer charge transport material.

[0095] 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.

[0096] 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.

[0097] [Chemical formula]

[0098] 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 , RT5 , R T6 , R T7 , and R T8 Each of these independently represents 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.

[0099] [ka]

[0100] 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.

[0101] Here, among the triarylamine derivative represented by structural formula (a-1) and the benzidine derivative represented by structural formula (a-2), in particular, "-C6H4-CH=CH-CH=C(R T7 )(R T8 Triarylamine derivatives having ")" and "-CH=CH-CH=C(R T15 )(R T16 A benzidine derivative having ) is preferred from the viewpoint of charge mobility.

[0102] 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.

[0103] 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.

[0104] Among the above-mentioned binder resins, polycarbonate resins and polyarylate resins are preferred because they more easily reduce the surface roughness of the charge transport layer and further suppress the occurrence of image flow, and polycarbonate resins (monopolymers of bisphenol A, bisphenol Z, bisphenol C, bisphenol TP, etc., or copolymers thereof) are even more preferred. Polycarbonate resin may be used individually or in combination of two or more types. Furthermore, for similar reasons, it is more preferable to include a polycarbonate resin that is a homopolymer of bisphenol Z among the polycarbonate resins.

[0105] The charge transport layer may contain inorganic particles in addition to the charge transport material and binder resin, as needed. When the charge transport layer (i.e., the organic photosensitive layer adjacent to the surface protective layer) contains inorganic particles, cracking of the metal oxide layer is suppressed if the surface protective layer is a metal oxide layer. Specifically, by including inorganic particles in the charge transport layer, the inorganic particles function as a reinforcing material for the charge transport layer, making the charge transport layer less prone to deformation and thus suppressing cracking of the metal oxide layer. Furthermore, the inclusion of inorganic particles in the charge transport layer makes dielectric breakdown of the charge transport layer less likely to occur even at high electric field strengths.

[0106] Inorganic particles used in the charge transport layer include silica particles, alumina particles, titanium oxide particles, potassium titanate, tin oxide particles, zinc oxide particles, zirconium oxide particles, barium sulfate particles, calcium oxide particles, calcium carbonate particles, and magnesium oxide particles. Inorganic particles may be used individually or in combination of two or more types. Among these, silica particles are particularly preferred because they have a high dielectric loss rate, making it difficult to reduce the electrical properties of the photoreceptor, and also because they suppress the occurrence of cracks in the metal oxide layer, which is the surface protective layer. The following describes in detail the silica particles suitable for charge transport layers.

[0107] Examples of silica particles include dry silica particles and wet silica particles. Examples of dry silica particles include fumed silica obtained by burning silane compounds, and deflagration silica obtained by explosively burning metallic silicon powder. Examples of wet silica particles include wet silica particles obtained by the neutralization reaction of sodium silicate and mineral acid (sedimentation silica synthesized and aggregated under alkaline conditions, gel silica particles synthesized and aggregated under acidic conditions, etc.), colloidal silica particles obtained by polymerizing acidic silicic acid in an alkaline state (silica sol particles, etc.), and sol-gel silica particles obtained by hydrolysis of organosilane compounds (e.g., alkoxysilanes, etc.). Among these, combustion-processed silica particles are preferable because they have fewer silanol groups on the surface and a low void structure, from the viewpoint of suppressing image defects due to the generation of residual potential and deterioration of other electrical properties (suppression of deterioration of fine line reproducibility).

[0108] It is preferable that the silica particles have their surfaces treated with a hydrophobic treatment agent. This reduces the number of silanol groups on the surface of the silica particles, making it easier to suppress the generation of residual potential. Examples of hydrophobic treatment agents include well-known silane compounds such as chlorosilanes, alkoxysilanes, and silazanes. Among these, silane compounds having a trimethylsilyl group, a decylsilyl group, or a phenylsilyl group are preferred as hydrophobic treatment agents, from the viewpoint of easily suppressing the generation of residual potential and suppressing image density unevenness caused by charging unevenness on the photoreceptor surface. In other words, it is preferable for the surface of silica particles to have a trimethylsilyl group, a decylsilyl group, or a phenylsilyl group. Examples of silane compounds containing a trimethylsilyl group (trimethylsilane compounds) include trimethylchlorosilane, trimethylmethoxysilane, and 1,1,1,3,3,3-hexamethyldisilazane. Examples of silane compounds containing a decylsilyl group (decylsilane compounds) include decyltrichlorosilane, decyldimethylchlorosilane, and decyltrimethoxysilane. Examples of silane compounds containing a phenyl group (phenylsilane compounds) include triphenylmethoxysilane and triphenylchlorosilane.

[0109] Condensation rate of hydrophobized silica particles (SiO in silica particles) 4- The Si-O-Si ratio in the bond (hereinafter also referred to as the "condensation rate of the hydrophobic treatment agent") is, for example, 90% or more relative to the silanol groups on the surface of the silica particles, preferably 91% or more, and more preferably 95% or more. By setting the condensation rate of the hydrophobic treatment agent within the above range, the silanol groups of the silica particles are further reduced, making it easier to suppress the generation of residual potential.

[0110] The condensation rate of the hydrophobic treatment agent indicates the ratio of condensed silicon to all bondable silicon sites in the condensation region detected by NMR (Nuclear Magnetic Resonance), and is measured as follows. First, silica particles are separated from the layer. Si CP / MAS NMR analysis is performed on the separated silica particles using a Bruker AVANCE III 400 to determine the peak area corresponding to the number of SiO substitutions. The values ​​for 2-substituted (Si(OH)2(0-Si)2-), 3-substituted (Si(OH)(0-Si)3-), and 4-substituted (Si(0-Si)4-) are defined as Q2, Q3, and Q4, respectively. The condensation ratio of the hydrophobic treatment agent is calculated using the formula: (Q2×2+Q3×3+Q4×4) / 4×(Q2+Q3+Q4).

[0111] The volume resistivity of silica particles is, for example, 10 11 Ω·cm or more is preferable, preferably 10 12 Ω·cm or more, more preferably 10 13 It is greater than or equal to Ω·cm. By keeping the volume resistivity of the silica particles within the above range, the deterioration of electrical properties is suppressed.

[0112] The volume resistivity of silica particles is measured as follows. The measurement environment is set to a temperature of 20°C and a humidity of 50% RH. First, separate the silica particles from the layer. Then, 20 cm 2 On the surface of a circular jig on which electrode plates are arranged, the separated silica particles to be measured are placed to a thickness of approximately 1 mm to 3 mm to form a silica particle layer. A 20 cm layer is then placed on top of this, as described above. 2 An electrode plate is placed on top of the silica particle layer, sandwiching it between the two plates. To eliminate the gaps between the silica particles, a 4 kg load is applied to the electrode plate placed on the silica particle layer, and then the thickness (cm) of the silica particle layer is measured. Both electrodes, above and below the silica particle layer, are connected to an electrometer and a high-voltage power generator. A high voltage is applied to both electrodes so that the electric field reaches a predetermined value, and the volume resistivity (Ω·cm) of the silica particles is calculated by reading the current value (A) that flows at this time. The formula for calculating the volume resistivity (Ω·cm) of silica particles is as shown in the formula below. In the formula, ρ represents the volume resistivity of the silica particles (Ω·cm), E represents the applied voltage (V), I represents the current value (A), I0 represents the current value at an applied voltage of 0V (A), and L represents the thickness of the silica particle layer (cm). In this evaluation, the volume resistivity at an applied voltage of 1000V was used. Formula: ρ = E × 20 / (I - I0) / L

[0113] The volume-average particle size of the inorganic particles containing silica particles is, for example, 20 nm to 200 nm, preferably 40 nm to 150 nm, more preferably 50 nm to 120 nm, and even more preferably 50 nm to 110 nm. When the volume-average particle size is within the above range, cracking of the metal oxide layer, which is the surface protective layer, and the generation of residual potential are more easily suppressed.

[0114] The volume-average particle size of inorganic particles is measured as follows. The measurement method for silica particles is shown below, but a similar method is used for other particles. The volume-average particle size of silica particles is determined by separating the silica particles from the layer, observing 100 primary silica particles at 40,000x magnification using a Scanning Electron Microscope (SEM), and measuring the longest and shortest diameters of each particle through image analysis. The equivalent spherical diameter is then calculated from the midpoint of these two values. The 50% diameter (D50v) at the cumulative frequency of the obtained equivalent spherical diameters is determined and measured as the volume-average particle size of the silica particles.

[0115] The amount of inorganic particles can be determined appropriately depending on their type, but in order to suppress cracking of the metal oxide layer, which is the surface protective layer, and the generation of residual potential, it is preferable that the amount be 40% by mass or more, more preferably 50% by mass or more, and even more preferably 55% by mass or more, relative to the total charge transport layer (solid content). Furthermore, while there is no particular upper limit to the inorganic particle content, from the standpoint of ensuring the characteristics of the charge transport layer, it is preferable to have 90% by mass or less, more preferably 80% by mass or less, more preferably 70% by mass or less, and even more preferably 65% ​​by mass or less. Furthermore, the inorganic particle content is preferably greater than the charge transport material content, for example, it is preferably 55% by mass or more and 90% by mass or less relative to the entire charge transport layer (solid content).

[0116] The charge transport layer may also contain other well-known additives.

[0117] -Characteristics of the charge transport layer- The surface roughness Ra (arithmetic mean surface roughness Ra) of the surface on the surface protection layer side of the charge transport layer is, for example, 0.5 μm or more and 4.5 μm or less, preferably 1 μm or more and 4 μm or less, and more preferably 1.5 μm or more and 3.5 μm or less. By setting the surface roughness Ra within the above range, the smoothness of the surface protective layer can be adjusted, and the coefficient of friction μ can be controlled. To achieve the surface roughness Ra within the above range, methods such as adjusting the particle size and content of inorganic particles, or adjusting the thickness of the charge transport layer, can be used.

[0118] This surface roughness Ra is measured as follows: First, the inorganic protective layer is removed to expose the layer to be measured. Then, a portion of that layer is cut out using a cutter or similar tool to obtain the sample for measurement. The surface roughness of this sample will be measured using a stylus-type surface roughness analyzer (e.g., Surfcom 1400A, manufactured by Tokyo Seimitsu Co., Ltd.). The measurement conditions will conform to JIS B0601-1994, with an evaluation length Ln = 4 mm, a reference length L = 0.8 mm, and a cutoff value of 0.8 mm.

[0119] The elastic modulus of the charge transport layer is, for example, 5 GPa or higher, preferably 6 GPa or higher, and more preferably 6.5 GPa or higher. If the elastic modulus of the charge transport layer is within the above range, cracking of the inorganic protective layer becomes easier to suppress. To achieve the elastic modulus of the charge transport layer within the above range, for example, methods such as adjusting the particle size and content of silica particles, or adjusting the type and content of charge transport material, can be used.

[0120] The elastic modulus of the charge transport layer is measured as follows: First, the inorganic protective layer is removed to expose the layer to be measured. Then, a portion of that layer is cut out using a cutter or similar tool to obtain the sample for measurement. For this sample, a depth profile is obtained using the continuous stiffness method (CSM) (U.S. Patent 4848141) with the Nano Indenter SA2 manufactured by MTS Systems, and the measurement is performed using the average value obtained from the indentation depth measurements from 30 nm to 100 nm.

[0121] The thickness of the charge transport layer is, for example, 10 μm to 40 μm, preferably 10 μm to 35 μm, and more preferably 15 μm to 30 μm. By keeping the thickness of the charge transport layer within the above range, cracking of the inorganic protective layer and the generation of residual potential become easier to suppress.

[0122] -Formation of a charge transport layer- The formation of the charge transport layer is not particularly limited, and well-known formation methods can be used. For example, it can be carried out by forming a coating film of a charge transport layer forming solution obtained by adding the above components to a solvent, drying the coating film, and heating it if necessary.

[0123] Suitable solvents for preparing the coating solution for forming the charge transport layer include common 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 can be used individually or in mixtures of two or more.

[0124] Conventional methods for applying a charge transport layer forming coating solution onto a charge generation layer include blade coating, wire bar coating, spray coating, immersion coating, bead coating, air knife coating, and curtain coating.

[0125] When dispersing particles (e.g., silica particles or fluororesin particles) in a coating solution for forming a charge transport layer, the dispersion method may involve media dispersers such as ball mills, vibrating ball mills, attritors, sand mills, and horizontal sand mills, or media-less dispersers such as stirrers, ultrasonic dispersers, roll mills, and high-pressure homogenizers. Examples of high-pressure homogenizers include impact 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.

[0126] Furthermore, after the formation of the charge transport layer and before the formation of the inorganic protective layer, if necessary, a step may be taken to replace the air contained in the organic photosensitive layer (i.e., charge generation layer, charge transport layer, etc.) formed on the conductive support with a gas with a higher oxygen concentration than the air.

[0127] (Single-layer photosensitive layer) A single-layer photosensitive layer (charge generation / charge transport layer) is, for example, a layer comprising a charge generation material, a charge transport material, and, if necessary, a binder resin and other well-known additives. These materials are the same as those described for the charge generation layer and the charge transport layer. Furthermore, the single-layer photosensitive layer is composed of a particle-containing layer containing surface-treated particles whose moisture adsorption rate in an environment with a relative humidity of 90% is 0.15% by mass or less. Furthermore, the content of the charge-generating material 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. In addition, the content of the charge-transporting material in the single-layer photosensitive layer is preferably 5% to 50% by mass, relative to the total solid content. 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. 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.

[0128] (Surface protective layer) The surface protective layer is a layer provided on the photosensitive layer and constitutes the outermost surface of the photoreceptor. The surface protective layer is provided, for example, to prevent chemical changes in the photosensitive layer when charged, or to further improve the mechanical strength of the photosensitive layer. In this embodiment, the static friction coefficient μ of the surface protective layer must be 0.3 or less. The surface protective layer having a static friction coefficient μ of 0.3 or less is preferably an inorganic protective layer, and in particular, it is preferably a metal oxide layer containing a group 13 element and oxygen.

[0129] The metal oxide layer will be explained below.

[0130] -Composition of the metal oxide layer- The metal oxide layer contains Group 13 elements and oxygen. The metal oxide layer containing the Group 13 elements and oxygen preferably includes metal oxides such as gallium oxide, aluminum oxide, indium oxide, and boron oxide, or mixed crystals thereof. Among these, the metal oxide layer containing the Group 13 elements and oxygen is particularly preferably made of gallium oxide, from the viewpoint of having excellent mechanical strength, light transmittance, n-type conductivity, and excellent controllability of its conductivity.

[0131] A metal oxide layer containing a Group 13 element and oxygen contains at least a Group 13 element (preferably gallium) and oxygen, but may also contain hydrogen as needed. The inclusion of hydrogen makes it easier to control the properties of the metal oxide layer composed of at least a Group 13 element (preferably gallium) and oxygen. For example, in a metal oxide layer containing gallium, oxygen, and hydrogen (for example, a metal oxide layer composed of gallium oxide containing hydrogen), by changing the composition ratio [O] / [Ga] from 1.0 to 1.5, 10 9 Ω cm or more 10 14 This makes it easier to control the volume resistivity within the range of Ω·cm.

[0132] In particular, it is preferable that the metal oxide layer contains Group 13 elements, oxygen, and hydrogen, and that the sum of the elemental composition ratios of Group 13 elements, oxygen, and hydrogen relative to all elements constituting the metal oxide layer is 90 atomic percent or more. Furthermore, the elemental composition ratio of oxygen and group 13 elements (oxygen / group 13 elements) is preferably 1.0 or more and less than 1.5, more preferably 1.03 or more and 1.47 or less, even more preferably 1.05 or more and 1.45 or less, and particularly preferably 1.10 or more and 1.40 or less. If the elemental composition ratio (oxygen / Group 13 element) of the material constituting the metal oxide layer is within the above range, image defects caused by scratches on the surface of the photoreceptor are suppressed. Similarly, it is desirable that the Group 13 element be gallium.

[0133] Furthermore, the sum of the elemental composition ratios of Group 13 elements (especially gallium), oxygen, and hydrogen relative to all elements constituting the metal oxide layer is 90 atomic percent or more. This suppresses the effects of Group 15 elements such as N, P, and As being mixed in, as they bond with Group 13 elements (especially gallium), making it easier to find an appropriate range for the oxygen and Group 13 element (especially gallium) composition ratio (oxygen / Group 13 element (especially gallium)) which can improve the hardness and electrical properties of the metal oxide layer. From the above viewpoint, the sum of the elemental composition ratios is preferably 95 atomic percent or more, more preferably 96 atomic percent or more, and even more preferably 97 atomic percent or more.

[0134] The metal oxide layer may contain, in addition to the Group 13 elements, oxygen, and hydrogen, one or more elements selected from C, Si, Ge, and Sn in the case of n-type, for control of the conductivity type. Alternatively, one or more elements selected from N, Be, Mg, Ca, and Sr in the case of p-type, for example.

[0135] Here, when the Group 13 elements, oxygen, and hydrogen are composed of gallium, oxygen, and hydrogen as needed, the following elemental composition ratios are preferred from the viewpoint of having excellent mechanical strength, light transmittance, flexibility, and excellent conductivity controllability. The elemental composition ratio of gallium is, for example, often between 15 atomic% and 50 atomic% of the total constituent elements of the metal oxide layer, preferably between 20 atomic% and 40 atomic% and more preferably between 20 atomic% and 30 atomic%. The elemental composition ratio of oxygen is, for example, often 30 to 70 atomic percent relative to the total constituent elements of the metal oxide layer, preferably 40 to 60 atomic percent, and more preferably 45 to 55 atomic percent. The elemental composition ratio of hydrogen is, for example, often between 10 atomic% and 40 atomic% of the total constituent elements of the metal oxide layer, preferably between 15 atomic% and 35 atomic% and more preferably between 20 atomic% and 30 atomic%.

[0136] Here, the elemental composition ratio and atomic number ratio of each element in the metal oxide layer, including the distribution in the thickness direction, are determined by Rutherford-back scattering (hereinafter referred to as "RBS"). For RBS, the NEC 3SDH Pelletron will be used as the accelerator, the CE&A RBS-400 as the end station, and the 3S-R10 as the system. CE&A's HYPRA program and other software will be used for analysis. The measurement conditions for RBS are as follows: He++ ion beam energy of 2.275 eV, detection angle of 160°, and grazing angle of approximately 109° relative to the incident beam.

[0137] RBS measurement is performed as follows: First, a He++ ion beam is incident perpendicularly on the sample, and the detector is set at 160° to the ion beam to measure the signal of backscattered He. The composition ratio and film thickness are determined from the detected He energy and intensity. To improve the accuracy of determining the composition ratio and film thickness, spectra may be measured at two detection angles. Accuracy can be improved by measuring at two detection angles with different depth resolution and backscatter dynamics and cross-checking the results. The number of He atoms backscattered by the target atom is determined by only three factors: 1) the atomic number of the target atom, 2) the energy of the He atoms before scattering, and 3) the scattering angle. The density is assumed by calculation from the measured composition and used to calculate the thickness. The density error is within 20%.

[0138] The elemental composition ratio of hydrogen is determined by hydrogen forward scattering (hereinafter referred to as "HFS"). For HFS measurements, the NEC 3SDH Pelletron accelerator and the CE&A RBS-400 end station are used, along with the 3S-R10 system. The CE&A HYPRA program is used for analysis. The HFS measurement conditions are as follows: He++ ion beam energy: 2.275 eV • Detection angle: 160° relative to the incident beam; Grazing angle: 30°

[0139] HFS measurement involves setting the detector at a 30° angle to the He++ ion beam and the sample at a 75° angle from the normal, thereby picking up the hydrogen signal scattered in front of the sample. It is advisable to cover the detector with aluminum foil to remove He atoms scattered along with the hydrogen. Quantitative analysis is performed by normalizing the hydrogen counts of the reference sample and the sample under test using their stopping power, and then comparing them. A sample of Si with H ion implanted and muscovite are used as reference samples. Muscovite is known to have a hydrogen concentration of 6.5 atomic percent. The amount of hydrogen adsorbed on the outermost surface is corrected by subtracting, for example, the amount of hydrogen adsorbed on a clean Si surface.

[0140] Furthermore, the metal oxide layer may have a distribution of compositional ratios in the thickness direction, or it may consist of multiple layers, depending on the purpose.

[0141] - Characteristics of the surface protective layer (preferably a metal oxide layer) - The surface roughness Ra (arithmetic mean surface roughness Ra) on the outer surface of the surface protective layer (preferably a metal oxide layer) (i.e., the surface of the electrophotographic photoreceptor 7) is, for example, 1 nm to 5 nm, preferably 1.5 nm to 4.5 nm, and more preferably 2 nm to 3.5 nm. By setting the surface roughness Ra within the above range, it becomes easier to achieve a static friction coefficient μ of 0.3 or less, and uneven charging is suppressed. To achieve the above-mentioned surface roughness Ra, one possible method is to set the surface roughness Ra of the surface on the surface protection layer side of the charge transport layer to the aforementioned range. Furthermore, the measurement of the surface roughness Ra on the outer surface of the inorganic surface layer is the same as the method for measuring the surface roughness Ra on the surface of the surface protective layer in the charge transport layer described above, except that the measurement is performed directly on the outer surface of the surface protective layer.

[0142] The volume resistivity of the surface protective layer is 5.0 × 10⁻⁶. 7Ωcm or greater: 1.0 × 10 12 A value of less than Ωcm is preferable. The volume resistivity of the surface protective layer is 8.0 × 10⁻¹⁰, which makes it easier to suppress the occurrence of image flow and to suppress image defects caused by scratches on the surface of the photoreceptor. 7 Ωcm or more 7.0 × 10 11 Ωcm or less is more preferable, and 1.0 × 10 8 Ωcm or more, 5.0 × 10 11 A value of Ωcm or less is even more preferable, and 5.0 × 10 8 Ωcm or greater: 2.0 × 10 11 A value of Ωcm or less is particularly preferred.

[0143] This volume resistivity is calculated from the resistance value measured using an nF Corporation LCR meter ZM2371 under conditions of frequency 1 kHz and voltage 1 V, based on the electrode area and sample thickness. The measurement sample may be a sample obtained by forming a protective film on an aluminum substrate under the same conditions as when the protective film to be measured was formed, and then forming a gold electrode on the resulting film by vacuum deposition, or it may be a sample obtained by peeling off the protective film from a fabricated electrophotographic photoreceptor, partially etching it, and then sandwiching it between a pair of electrodes.

[0144] A preferred example of a surface protective layer is a metal oxide layer, which is preferably a non-single-crystalline film such as a microcrystalline film, polycrystalline film, or amorphous film. Among these, amorphous films are particularly desirable for their surface smoothness, while microcrystalline films are more desirable in terms of hardness. The growth cross-section of the metal oxide layer may have a columnar structure, but from the viewpoint of slipperiness, a highly flat structure is desirable, and an amorphous structure is preferable. Crystalline and amorphous properties are determined by the presence or absence of dots or lines in the diffraction pattern obtained by RHEED (Reflection High-Frequency Electron Diffraction) measurement.

[0145] The elastic modulus of the surface protective layer (preferably a metal oxide layer) is often 30 GPa or more and 80 GPa or less, and more preferably 40 GPa or more and 65 GPa or less. If the elastic modulus is kept within the above range, the occurrence of surface protection depressions (dent-like scratches), peeling, and cracking will be more easily suppressed. This modulus of elasticity is calculated using the Nano Indenter SA2 manufactured by MTS Systems, Inc., with a depth profile obtained by the continuous stiffness method (CSM) (U.S. Patent 4848141), and the average value obtained from measurements taken from an indentation depth of 30 nm to 100 nm is used. The measurement conditions are as follows. • Measurement environment: 23℃, 55%RH • Indenter used: Diamond triangular pyramidal indenter (Berkovic indenter) • Test mode: CSM mode The measurement sample may be a sample prepared by depositing the surface protective layer on a substrate under the same conditions as when the protective layer was deposited, or it may be a sample prepared by peeling off the surface protective layer from the electrophotographic photoreceptor after fabrication and partially etching it.

[0146] The thickness of the surface protective layer is often, for example, between 0.2 μm and 10.0 μm, and preferably between 0.4 μm and 5.0 μm. By keeping the film thickness within the above range, the occurrence of depressions (dent-like scratches), peeling, and cracking of the surface protective layer becomes easier to suppress.

[0147] -Formation of surface protective layer- For forming a metal oxide layer, which is a preferred example of a surface protective layer, known vapor deposition methods such as plasma CVD (Chemical Vapor Deposition), organometallic vapor deposition, molecular beam evaporation, vapor deposition, and sputtering can be used.

[0148] The following explanation describes the formation of a metal oxide layer, illustrating this with specific examples and illustrating an example of a film deposition apparatus in the diagram. While the following explanation focuses on the formation of a metal oxide layer composed of gallium, oxygen, and hydrogen, it is not limited to this method; any known formation method should be applied depending on the desired composition of the metal oxide layer.

[0149] Figure 4 is a schematic diagram showing an example of a film deposition apparatus used for forming a metal oxide layer. Figure 4(A) shows a schematic cross-sectional view of the film deposition apparatus viewed from the side, and Figure 4(B) shows a schematic cross-sectional view between A1 and A2 of the film deposition apparatus shown in Figure 4(A). In Figure 4, 210 is the film deposition chamber, 211 is the exhaust port, 212 is the substrate rotation section, 213 is the substrate support member, 214 is the substrate, 215 is the gas introduction pipe, 216 is the shower nozzle having an opening for injecting the gas introduced from the gas introduction pipe 215, 217 is the plasma diffusion section, 218 is the high-frequency power supply section, 219 is the flat plate electrode, 220 is the gas introduction pipe, and 221 is the high-frequency discharge tube section.

[0150] In the film deposition apparatus shown in Figure 4, an exhaust port 211 connected to a vacuum exhaust device (not shown) is provided at one end of the film deposition chamber 210, and a plasma generator consisting of a high-frequency power supply unit 218, a flat plate electrode 219, and a high-frequency discharge tube unit 221 is provided on the side of the film deposition chamber 210 opposite to the side with the exhaust port 211. This plasma generator consists of a high-frequency discharge tube section 221, a flat plate electrode 219 positioned inside the high-frequency discharge tube section 221 with its discharge surface facing the exhaust port 211, and a high-frequency power supply section 218 positioned outside the high-frequency discharge tube section 221 and connected to the side of the flat plate electrode 219 opposite to the discharge surface. A gas introduction pipe 220 for supplying gas into the high-frequency discharge tube section 221 is connected to the high-frequency discharge tube section 221, and the other end of this gas introduction pipe 220 is connected to a first gas supply source (not shown).

[0151] Alternatively, the plasma generator shown in Figure 5 may be used instead of the plasma generator provided in the film deposition apparatus shown in Figure 4. Figure 5 is a schematic diagram showing another example of a plasma generator used in the film deposition apparatus shown in Figure 4, and is a side view of the plasma generator. In Figure 5, 222 represents a high-frequency coil, 223 represents a quartz tube, and 220 is the same as that shown in Figure 4. This plasma generator consists of a quartz tube 223 and a high-frequency coil 222 provided along the outer surface of the quartz tube 223, with one end of the quartz tube 223 connected to a film deposition chamber 210 (not shown in Figure 5). The other end of the quartz tube 223 is connected to a gas introduction pipe 220 for introducing gas into the quartz tube 223.

[0152] In Figure 4, a rod-shaped shower nozzle 216 extending along the discharge surface is connected to the discharge surface side of the flat electrode 219. One end of the shower nozzle 216 is connected to a gas introduction pipe 215, which is connected to a second gas supply source (not shown) located outside the film deposition chamber 210. Furthermore, a substrate rotation section 212 is provided within the film deposition chamber 210, and a cylindrical substrate 214 is attached to the substrate rotation section 212 via a substrate support member 213 so that the longitudinal direction of the shower nozzle 216 and the axial direction of the substrate 214 face each other. During film deposition, the substrate rotation section 212 rotates, causing the substrate 214 to rotate in the circumferential direction. For example, a photoreceptor with an organic photosensitive layer already laminated is used as the substrate 214.

[0153] The metal oxide layer can be formed, for example, as follows: First, oxygen gas (or helium (He) diluted oxygen gas), helium (He) gas, and hydrogen (H2) gas as needed are introduced into the high-frequency discharge tube section 221 from the gas introduction tube 220, and a 13.56 MHz radio wave is supplied to the flat electrode 219 from the high-frequency power supply section 218. At this time, a plasma diffusion section 217 is formed so as to spread radially from the discharge surface side of the flat electrode 219 toward the exhaust port 211 side. Here, the gas introduced from the gas introduction tube 220 flows through the film deposition chamber 210 from the flat electrode 219 side toward the exhaust port 211 side. The flat electrode 219 may also be surrounded by an earth shield.

[0154] Next, trimethylgallium gas is introduced into the deposition chamber 210 via the gas introduction tube 215 and the shower nozzle 216 located downstream of the plate electrode 219, which is an activation means, thereby forming a non-single-crystal film containing gallium, oxygen, and hydrogen on the surface of the substrate 214. As the substrate 214, for example, a substrate on which an organic photosensitive layer is formed is used.

[0155] The surface temperature of the substrate 214 during film formation of the metal oxide layer is preferably 150°C or lower, more preferably 100°C or lower, and particularly preferably between 30°C and 100°C, since an organic photoreceptor having an organic photosensitive layer is used. Even if the surface temperature of the substrate 214 is below 150°C at the start of film deposition, if it rises above 150°C due to the influence of plasma, the organic photosensitive layer may be damaged by heat. Therefore, it is desirable to control the surface temperature of the substrate 214 taking this effect into consideration. The surface temperature of the substrate 214 may be controlled by at least one of a heating means and a cooling means (not shown in the figure), or it may be left to the natural temperature rise during discharge. When heating the substrate 214, a heater may be installed on the outside or inside of the substrate 214. When cooling the substrate 214, a cooling gas or liquid may be circulated inside the substrate 214. To avoid a temperature rise on the substrate 214 surface due to electrical discharge, it is effective to adjust the high-energy gas flow hitting the substrate 214 surface. In this case, conditions such as gas flow rate, discharge output, and pressure are adjusted to achieve the desired temperature.

[0156] Alternatively, instead of trimethylgallium gas, organometallic compounds containing aluminum or hydrides such as diborane can be used, and two or more of these may be mixed. For example, by introducing trimethylindium into the deposition chamber 210 via a gas introduction tube 215 and a shower nozzle 216 during the initial stages of metal oxide layer formation, a film containing nitrogen and indium is deposited on the substrate 214. This film absorbs ultraviolet light that is generated during continuous deposition and degrades the organic photosensitive layer. Therefore, damage to the organic photosensitive layer caused by ultraviolet light during deposition is suppressed.

[0157] Furthermore, for dopant doping during film formation, SiH3 and SnH4 are used in gaseous form for n-type films, and biscyclopentadienylmagnesium, dimethylcalcium, dimethylstrontium, etc., are used in gaseous form for p-type films. In addition, known methods such as thermal diffusion and ion implantation may be used to dopant elements into the surface layer. Specifically, for example, a conductive metal oxide layer of the n-type, p-type, etc., is obtained by introducing a gas containing at least one dopant element into the deposition chamber 210 via a gas introduction pipe 215 and a shower nozzle 216.

[0158] In the film deposition apparatus described using Figures 4 and 5, the activated nitrogen or activated hydrogen formed by the discharge energy may be independently controlled by providing multiple activation devices, or a gas containing both nitrogen and hydrogen atoms, such as NH3, may be used. Furthermore, H2 may be added. Alternatively, conditions that allow for the liberation and generation of activated hydrogen from organometallic compounds may be used. In this way, activated carbon atoms, gallium atoms, nitrogen atoms, hydrogen atoms, etc., exist in a controlled state on the surface of substrate 214. The activated hydrogen atoms have the effect of removing hydrogen molecules from hydrocarbon groups such as methyl and ethyl groups that constitute organometallic compounds. As a result, a hard film (metal oxide layer) is formed that constitutes a three-dimensional bond.

[0159] The plasma generation means of the film deposition apparatus shown in Figures 4 and 5 uses a high-frequency oscillator, but is not limited to this. For example, a microwave oscillator may be used, or an electrocyclotron resonance or helicon plasma apparatus may be used. In the case of a high-frequency oscillator, it may be either an inductive or capacitive type. Furthermore, two or more types of these devices may be used in combination, or two or more devices of the same type may be used. A high-frequency oscillator is desirable to suppress the temperature rise of the substrate 214 surface due to plasma irradiation, but a device to suppress heat irradiation may also be provided.

[0160] When using two or more different plasma generators (plasma generating means), it is desirable to ensure that discharges occur simultaneously at the same pressure. Alternatively, a pressure difference may be provided between the discharge region and the film deposition region (the area where the substrate is placed). These devices may be arranged in series with respect to the gas flow formed within the film deposition apparatus from the gas introduction area to the gas discharge area, or each device may be arranged facing the film deposition surface of the substrate.

[0161] For example, when two types of plasma generating means are installed in series with respect to the gas flow, taking the film deposition apparatus shown in Figure 4 as an example, the shower nozzle 216 is used as an electrode to cause a discharge in the film deposition chamber 210. In this case, for example, a high-frequency voltage is applied to the shower nozzle 216 via the gas introduction pipe 215 to cause a discharge in the film deposition chamber 210 using the shower nozzle 216 as an electrode. Alternatively, instead of using the shower nozzle 216 as an electrode, a cylindrical electrode is provided between the substrate 214 and the flat electrode 219 in the film deposition chamber 210, and this cylindrical electrode is used to cause a discharge in the film deposition chamber 210. Furthermore, when using two different types of plasma generators under the same pressure, for example, a microwave oscillator and a high-frequency oscillator, the excitation energy of the excited species can be significantly varied, which is effective for controlling the film quality. Also, the discharge may be performed near atmospheric pressure (70,000 Pa to 110,000 Pa). When performing the discharge near atmospheric pressure, it is desirable to use He as the carrier gas.

[0162] For example, the formation of the metal oxide layer involves placing a substrate 214, on which an organic photosensitive layer has been formed on a conductive support, in a deposition chamber 210, and introducing mixed gases of different compositions to form an inorganic surface layer.

[0163] Furthermore, regarding film deposition conditions, for example, when using high-frequency discharge, it is desirable to set the frequency in the range of 10 kHz to 50 MHz in order to deposit a high-quality film at low temperatures. Also, although the output depends on the size of the substrate 214, it is 0.01 W / cm² relative to the surface area of ​​the substrate. 2 More than 0.2W / cm 2 The following range is desirable: The rotational speed of the base 214 should preferably be in the range of 0.1 rpm to 500 rpm.

[0164] [Charging device] The charging device 15 charges the surface of the photoreceptor 12. The charging device 15 includes, for example, a charging member 14 that is provided in contact with or without contact with the surface of the photoreceptor 12 to charge the surface of the photoreceptor 12, and a power supply 28 (an example of a voltage application unit for the charging member) that applies a charging voltage to the charging member 14. The power supply 28 is electrically connected to the charging member 14.

[0165] Examples of charging components 14 in the charging device 15 include contact-type chargers using conductive charging rolls, charging brushes, charging films, charging rubber blades, charging tubes, etc. Other examples of charging components 14 include non-contact type roller chargers, scorotron chargers or corotron chargers utilizing corona discharge, and other known chargers.

[0166] [Electrostatic image forming device] The electrostatic image forming apparatus 16 forms an electrostatic image on the surface of a charged photoreceptor 12. Specifically, for example, the electrostatic image forming apparatus 16 irradiates the surface of the photoreceptor 12, which has been charged by a charging member 14, with light L modulated based on the image information of the image to be formed, thereby forming an electrostatic image on the photoreceptor 12 that corresponds to the image information.

[0167] Examples of electrostatic image forming apparatus 16 include optical equipment having a light source that exposes an image-like object with light such as semiconductor laser light, LED light, or liquid crystal shutter light.

[0168] [Developing equipment] The developing device 18 is located, for example, downstream of the photoreceptor 12 in the rotational direction from the irradiation position of light L by the electrostatic image forming device 16. The developing device 18 has a storage section for containing the developer. This storage section contains an electrostatic image developer having toner. The toner is stored, for example, in a charged state within the developing device 18.

[0169] The developing apparatus 18 includes, for example, a developing member 18A that develops the electrostatic image formed on the surface of the photoreceptor 12 using a developer containing toner, and a power supply 32 that applies a developing voltage to the developing member 18A. The developing member 18A is electrically connected to, for example, the power supply 32.

[0170] The developing element 18A of the developing device 18 is selected according to the type of developer, but an example is a developing roll having a developing sleeve with a magnet built in.

[0171] The developing device 18 (including the power supply 32) is electrically connected to, for example, a control device 36 provided in the image forming apparatus 10, and is driven and controlled by the control device 36 to apply a developing voltage to the developing member 18A. The developing member 18A, to which the developing voltage has been applied, is charged to a developing potential corresponding to the developing voltage. The developing member 18A, charged to the developing potential, then holds, for example, the developer contained in the developing device 18 on its surface and supplies the toner contained in the developer from inside the developing device 18 to the surface of the photoreceptor 12. On the surface of the photoreceptor 12 to which the toner has been supplied, the formed electrostatic charge image is developed as a toner image.

[0172] [Transfer device] The transfer device 31 is provided, for example, downstream of the developing member 18A in the rotational direction of the photoreceptor 12. The transfer device 31 includes, for example, a transfer member 20 that transfers the toner image formed on the surface of the photoreceptor 12 to the recording medium 30A, and a power supply 30 that applies a transfer voltage to the transfer member 20. The transfer member 20 is, for example, cylindrical and transports the recording medium 30A between itself and the photoreceptor 12. The transfer member 20 is electrically connected to, for example, the power supply 30.

[0173] Examples of the transfer member 20 include contact-type transfer chargers using belts, rollers, films, rubber cleaning blades, etc., and non-contact type transfer chargers that are known themselves, such as scorotron transfer chargers or corotron transfer chargers that utilize corona discharge.

[0174] The transfer device 31 (including the power supply 30) is electrically connected to, for example, a control device 36 provided in the image forming apparatus 10, and is driven and controlled by the control device 36 to apply a transfer voltage to the transfer member 20. The transfer member 20, to which the transfer voltage has been applied, is charged to a transfer potential corresponding to the transfer voltage.

[0175] When a transfer voltage with the opposite polarity to the toner that constitutes the toner image formed on the photoreceptor 12 is applied to the transfer member 20 from the power supply 30 of the transfer member 20, for example, a transfer electric field with an electric field strength that moves each toner constituting the toner image on the photoreceptor 12 from the photoreceptor 12 to the transfer member 20 side by electrostatic force is formed in the region where the photoreceptor 12 and the transfer member 20 face each other (see transfer region 32A in Figure 1).

[0176] The recording medium 30A is housed in, for example, a housing (not shown), and is transported from this housing along a transport path 34 by a plurality of transport members (not shown) to the transfer region 32A, which is the region where the photoreceptor 12 and the transfer member 20 face each other. In the example shown in Figure 1, it is transported in the direction of arrow B. Once the recording medium 30A reaches the transfer region 32A, the toner image on the photoreceptor 12 is transferred to the recording medium 30A by a transfer electric field formed in the region, for example, when a transfer voltage is applied to the transfer member 20. That is, for example, the toner image is transferred onto the recording medium 30A by the movement of toner from the surface of the photoreceptor 12 to the recording medium 30A. The toner image on the photoreceptor 12 is then transferred onto the recording medium 30A by the transfer electric field.

[0177] [Cleaning device] The cleaning device 22 has a cleaning blade 22A that contacts the surface of the photoreceptor 12 and cleans the surface of the photoreceptor 12.

[0178] The cleaning device 22 is located downstream of the transfer area 32A in the rotational direction of the photoreceptor 12. After the toner image has been transferred to the recording medium 30A, the cleaning device 22 cleans any residual toner adhering to the photoreceptor 12. In addition to residual toner, the cleaning device 22 also cleans any other adhering substances such as paper dust.

[0179] The cleaning device 22 has a cleaning blade 22A, and removes deposits from the surface of the photoreceptor 12 by bringing the tip of the cleaning blade 22A into contact with the photoreceptor 12 in a direction opposite to the rotation direction of the photoreceptor 12.

[0180] Now, with reference to Figure 6, the cleaning device 22 will be described. Figure 6 is a schematic diagram showing the installation configuration of the cleaning blade 22A in the cleaning device 22 shown in Figure 1. As shown in Figure 6, the tip of the cleaning blade 22A is facing in a direction opposite to the rotation direction of the photoreceptor 12 (arrow direction), and in this state it is in contact with the surface of the photoreceptor 12.

[0181] When the cleaning blade 22A is brought into contact with the surface of the photoreceptor 12, it is preferable that the following conditions be met. The working angle WA of the cleaning blade 22A with respect to the photoreceptor 12, that is, the angle θ 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 6) and the non-deformable portion of the cleaning blade 22A, is preferably 8° to 14°, and more preferably 10° to 12°. Furthermore, the amount of penetration of the cleaning blade 22A into the photoreceptor 12 is preferably 0.5 mm or more and 1.2 mm or less, and more preferably 0.9 mm or more and 1.1 mm or less. Based on the above, it is preferable that the contact angle WA when the cleaning blade 22A contacts the surface of the photoreceptor 12 is 8° or more and 14° or less, and the penetration depth is 0.8 mm or more and 1.2 mm or more.

[0182] The cleaning blade 22A is supported by a support member (not shown in Figure 6) attached to the side opposite to the side that contacts the photoreceptor 12. This support member presses the cleaning blade 22A against the photoreceptor 12 with the aforementioned pressure. Examples of support members include metal materials such as aluminum and stainless steel. A bonding layer, such as an adhesive, may be present between the support member and the cleaning blade 22A to ensure their adhesion. The cleaning device may include known components other than the cleaning blade 22A and the support member that supports it.

[0183] As the cleaning blade 22A, it is preferable to use a cleaning blade (hereinafter also referred to as a "specific cleaning blade") having a contact area where the ratio of the 100% modulus (M100 [MPa]) to the rebound modulus (Re [%]) (M100 / Re) is 0.25 or more, such that the difference Δ of the amount of strain between the cleaning blade when it is stationary and when it is in operation is 100 μST or less. In other words, a preferred example of a cleaning blade is one in which at least the contact area with the photoreceptor has a ratio (M100 / Re) of 0.25 or more between the 100% modulus (M100 [MPa]) and the rebound modulus (Re [%]).

[0184] -Specific Cleaning Blade- The following describes the specific cleaning blades. The specific cleaning blade has a contact member whose ratio of 100% modulus (M100 [MPa]) to rebound modulus (Re [%]) (M100 / Re) is 0.25 or higher.

[0185] Here, the 100% modulus (M100 [MPa]) is determined in accordance with JIS K 6251 (2010), using a dumbbell-shaped No. 3 test specimen, measured at a tensile speed of 500 mm / min, and calculated from the stress at 100% strain. The measuring device used is a Strograph AE Elastomer manufactured by Toyo Seiki Co., Ltd. Furthermore, the rebound modulus (Re) is determined in accordance with JIS K 6255 (1996) using a Lübke rebound modulus tester at a temperature of 23°C.

[0186] The specific cleaning blade may have a single layer, a double layer, a triple or more layer configuration, or any other configuration, as long as it has the contact portion described above. Examples of single-layer cleaning blades include cleaning blades in which the entire structure, including the contact portion with the photoreceptor, is made from a single material (i.e., cleaning blades consisting of contact members). Examples of a two-layer cleaning blade include a first layer formed over the entire ventral surface including the contact portion with the photoreceptor and consisting of a contact member, and a second layer formed on the rear side of the first layer and consisting of a different material from the contact member, which serves as a back layer. Examples of cleaning blades with three or more layers include cleaning blades that have another layer between the first and second layers in the two-layer cleaning blade described above. The cleaning blade is used, for example, by being bonded to a rigid plate-shaped support material.

[0187] (Composition of contact members) The contact member is not particularly limited as long as the M100 / Re value is 0.25 or greater. Examples of contact members include members containing polyurethane rubber.

[0188] -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 polymerizing a resin having functional groups that can react with the isocyanate groups of the polyisocyanate, in addition to the polyol component, as needed.

[0189] It is preferable that the polyurethane rubber has hard segments and soft segments. "Hard segments" and "soft segments" refer to segments in the polyurethane rubber material in which the material constituting the former is relatively harder than the material constituting the latter, and the material constituting the latter is relatively softer than the material constituting the former. The materials that make up the hard segment (hard segment material) include low molecular weight polyol components among polyol components, and resins having functional groups that can react with the isocyanate groups of polyisocyanates. On the other hand, the materials that make up the soft segment (soft segment material) include high molecular weight polyol components among polyol components.

[0190] Here, the average particle size of the hard segment aggregates is preferably 1 μm or more and 10 μm or less, and more preferably 1 μm or more and 5 μm or less. By making the average particle size of the hard segment aggregates 1 μm or larger, the frictional resistance of the contact material surface is more easily reduced. As a result, blade behavior is stabilized, and localized wear is more easily suppressed. On the other hand, by making the average particle size of the hard segment aggregates 10 μm or less, the occurrence of chipping becomes easier to suppress.

[0191] The average particle size of hard segment aggregates is measured as follows: Using a polarizing microscope (Olympus BX51-P), images are captured at 20x magnification, and the images are binarized through image processing. Five points are measured for each cleaning blade (measuring the particle size of five aggregates per point), and the particle size (equivalent to a circle diameter) of the aggregates is measured for all 20 cleaning blades. The average particle size is then calculated from a total of 500 particles. For image binarization, the image processing software OLYMPUS Stream essentials (manufactured by Olympus Corporation) is used, and the hue / saturation / luminance thresholds are adjusted so that the crystalline and hard segment aggregates appear black, and the amorphous parts (corresponding to soft segments) appear white.

[0192] • Polyol components The polyol component includes both high molecular weight polyols and low molecular weight polyols.

[0193] The polymeric polyol component is a polyol with a number-average molecular weight of 500 or more (preferably 500 to 5000). Examples of polymeric polyol components include well-known polyols such as 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, and polyether polyols. Examples of commercially available polymeric polyols include Praxel 205 and Praxel 240 manufactured by Daicel Corporation.

[0194] Here, the number-average molecular weight is the value measured by gel permeation chromatography (GPC). The same applies hereafter.

[0195] These polymeric polyols may be used individually or in combination of two or more types.

[0196] The polymerization ratio of the high-molecular-weight polyol component is preferably 30 mol% to 50 mol% relative to the total polymerization component of the polyurethane rubber, and more preferably 40 mol% to 50 mol%.

[0197] Low molecular weight polyol components are polyols with a molecular weight (number average molecular weight) of less than 500. Low molecular weight polyols are materials that function as chain length extenders and crosslinking agents.

[0198] Examples of low molecular weight polyol components include 1,3-propanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol, 1,9-nonanediol, 1,10-decanediol, 1,11-undecanediol, 1,12-dodecanediol, 1,13-tridecanediol, 1,14-tetradecanediol, 1,18-octadecanediol, and 1,20-eicosanediol. Among these, 1,4-butanediol is preferably used as the low molecular weight polyol component.

[0199] Examples of low molecular weight polyol components include diols (bifunctional), triols (trifunctional), or tetraols (tetrafunctional), which are well known as chain length extenders and crosslinking agents. These polyols may be used individually or in combination of two or more types.

[0200] The polymerization ratio of the low molecular weight polyol component is preferably more than 50 mol% and 75 mol% or less relative to the total polymerization component of the polyurethane rubber, more preferably 52 mol% to 75 mol%, more preferably 55 mol% to 75 mol%, and even more preferably 55 mol% to 60 mol%.

[0201] Also, as the low molecular weight polyol component, it is preferable to contain 1,4 - butanediol in an amount exceeding 50 mol% and not exceeding 75 mol% (preferably 52 mol% or more and 75 mol%, more preferably 55 mol% or more and 75 mol% or less, still more preferably 55 mol% or more and 60 mol% or less) based on the total polyol component (high molecular weight polyol + low molecular weight polyol). By setting the proportion of 1,4 - butanediol to exceed 50 mol%, it becomes easier to suppress local wear. On the other hand, by setting the proportion of 1,4 - butanediol to 75 mol% or less, the occurrence of chipping is easily suppressed. In addition, the proportion of 1,4 - butanediol with respect to the total low molecular weight polyol component is 80 mol% or more, preferably 90 mol% or more, and more preferably 100 mol%. That is, it is most preferable to use 1,4 - butanediol as the total low molecular weight polyol component.

[0202] · Polyisocyanate component Examples of the polyisocyanate component 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).

[0203] As the polyisocyanate component, 4,4'-diphenylmethane diisocyanate (MDI), 1,5 - naphthalene diisocyanate (NDI), and hexamethylene diisocyanate (HDI) are more desirable.

[0204] These polyisocyanate components may be used alone or in combination of two or more.

[0205] The polymerization ratio of the polyisocyanate component is preferably 5 mol% or more and 25 mol% or less, more preferably 10 mol% or more and 20 mol% or less, based on the total polymerization components of the polyurethane rubber.

[0206] · Resin having a functional group capable of reacting with an isocyanate group The resin having a functional group capable of reacting with an isocyanate group (hereinafter referred to as "functional group-containing resin") is preferably a flexible resin, and more preferably an aliphatic resin having a linear structure from the viewpoint of flexibility. Specific examples of the functional group-containing resin include an acrylic resin containing two or more hydroxyl groups, a polybutadiene resin containing two or more hydroxyl groups, an epoxy resin having two or more epoxy groups, and the like.

[0207] Examples of commercially available products of acrylic resins containing two or more hydroxyl groups include Actflow manufactured by Soken Chemical & Engineering Co., Ltd. (grades: UMB-2005B, UMB-2005P, UMB-2005, UME-2005, etc.).

[0208] Examples of commercially available products of polybutadiene resins containing two or more hydroxyl groups include R-45HT manufactured by Idemitsu Kosan Co., Ltd.

[0209] The epoxy resin having two or more epoxy groups is not one having a hard and brittle property like a conventional general epoxy resin, and one having a more flexible and tough property than a conventional epoxy resin is desirable. As the above epoxy resin, for example, in terms of the molecular structure, those having a structure (flexible skeleton) capable of increasing the mobility of the main chain in the main chain structure are suitable. Examples of the flexible skeleton include an alkylene skeleton, a cycloalkane skeleton, a polyoxyalkylene skeleton, etc., and a polyoxyalkylene skeleton is particularly suitable. Also, in terms of physical properties, an epoxy resin having a lower viscosity compared to the molecular weight than a conventional epoxy resin is suitable. Specifically, it is desirable that the weight average molecular weight is within the range of 900 ± 100, and the viscosity at 25 ° C is within the range of 15000 ± 5000 mPa·s, and more preferably within the range of 15000 ± 3000 mPa·s. Examples of commercially available products of epoxy resins having this property include EPLICON EXA-4850-150 manufactured by DIC.

[0210] The polymerization ratio of the functional group-containing resin should be within a range that does not impair the effectiveness of the cleaning blade according to this embodiment.

[0211] • Manufacturing method of polyurethane rubber Polyurethane rubber is manufactured using common polyurethane manufacturing methods such as the prepolymer method and the one-shot method. The prepolymer method is suitable for this embodiment because it yields polyurethane with excellent abrasion resistance and chipping properties, but the manufacturing method is not limiting. The cleaning blade is manufactured by forming the cleaning blade composition prepared by the above method into a sheet using, for example, centrifugal molding or extrusion molding, and then cutting it.

[0212] Examples of catalysts used in the production of polyurethane rubber include amine compounds such as tertiary amines, quaternary ammonium salts, and organometallic compounds such as organotin compounds. Examples of the above-mentioned tertiary amines include trialkylamines such as triethylamine, tetraalkyldiamines such as N,N,N',N'-tetramethyl-1,3-butanediamine, amino alcohols such as dimethylethanolamine, ethoxylated amines, ethoxylated diamines, esteramines such as 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.

[0213] 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.

[0214] Examples of organotin compounds include dialkyltin compounds such as dibutyltin dilaurate and dibutyltin di(2-ethylhexoate), as well as stannous 2-ethylcaproate and stannous oleate.

[0215] Among these catalysts, triethylenediamine (TEDA), a tertiary ammonium salt, is preferred in terms of hydrolysis resistance, while quaternary ammonium salts are preferred in terms of processability. Among 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 preferred due to their high reaction activity.

[0216] The catalyst content 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. These can be used individually or in combination of two or more types.

[0217] (Physical properties of contact members) The M100 / Re value of the contact member is 0.25 or higher, preferably 0.28 or higher, and more preferably 0.3 or higher. Furthermore, from the viewpoint of chipping resistance, the upper limit of the M100 / Re value of the contact member is preferably 1.0 or lower, and more preferably 0.9 or lower. The Re[%] of the contact member is preferably 25% or more, more preferably 28% or more, and even more preferably 30% or more. The upper limit of the Re[%] of the contact portion is preferably 60% or less, and more preferably 40% or less, from the viewpoint of suppressing blade noise and wear resistance. The M100 [MPa] of the contact member is preferably 4 MPa to 10 MPa, and more preferably 5 MPa to 9 MPa, from the viewpoint of wear resistance and chipping resistance.

[0218] The method for controlling the M100 / Re value and the Re value in the contact member is not particularly limited. For example, if the contact member contains polyurethane rubber, the values ​​can be adjusted to the above range by selecting the type and amount of each polymerization component of the polyurethane rubber, as well as the manufacturing conditions.

[0219] The weight-average molecular weight of the contact member is preferably between 1000 and 4000, and more preferably between 1500 and 3500. The weight-average molecular weights mentioned above were measured using gel permeation chromatography (GPC).

[0220] (Composition of non-contact components) This section describes the composition of the non-contact member in a cleaning blade where the contact member and the area other than the contact member (hereinafter also referred to as the "non-contact member") are made of different materials.

[0221] The non-contact member can be any known material without particular limitation, as long as it has the function of supporting the contact member. Specifically, examples of materials used for the non-contact member include polyurethane rubber, silicone rubber, fluororubber, proloprene rubber, and butadiene rubber. Among these, polyurethane rubber is preferred. Examples of polyurethane rubber include ester-based polyurethane and ether-based polyurethane, with ester-based polyurethane being particularly desirable.

[0222] (Manufacturing of cleaning blades) The cleaning blade having a single-layer structure is manufactured, for example, by the method for forming the contact member described above. The cleaning blade having a two-layer structure or a three-layer or more structure is produced, for example, by bonding a first layer as a contact member and a second layer as a non-contact member (a plurality of layers in the case of a three-layer or more layer structure) to each other. As the bonding method, a double-sided tape, various adhesives, etc. are preferably used. Also, the plurality of layers may be bonded by pouring the materials of each layer into the mold with a time difference during molding and bonding the materials without providing an adhesive layer.

[0223] [Charge removal device] The charge removal device 24 is provided, for example, on the downstream side in the rotation direction of the photoreceptor 12 from the cleaning device 22. After transferring the toner image, the charge removal device 24 exposes the surface of the photoreceptor 12 to remove the charge. Specifically, for example, the charge removal device 24 is electrically connected to a control device 36 provided in the image forming apparatus 10, and is driven and controlled by the control device 36 to expose the entire surface of the photoreceptor 12 (specifically, for example, the entire surface of the image forming region) to remove the charge.

[0224] Examples of the charge removal device 24 include devices having a light source such as a tungsten lamp that irradiates white light or a light emitting diode (LED) that irradiates red light.

[0225] [Fixing device] The fixing device 26 is provided, for example, on the downstream side in the conveyance direction of the conveyance path 34 of the recording medium 30A from the transfer region 32A. The fixing device 26 has a fixing member 26A and a pressing member 26B arranged in contact with the fixing member 26A, and fixes the toner image transferred onto the recording medium 30A at the contact portion between the fixing member 26A and the pressing member 26B. Specifically, for example, the fixing device 26 is electrically connected to a control device 36 provided in the image forming apparatus 10, and is driven and controlled by the control device 36 to fix the toner image transferred onto the recording medium 30A to the recording medium 30A by heat and pressure.

[0226] Examples of the fixing device 26 include known fixing devices such as hot roller fixing devices and oven fixing devices. Specifically, for example, the fixing device 26 may be a well-known fixing device comprising a fixing roll or fixing belt as a fixing member 26A and a pressure roll or pressure belt as a pressure member 26B.

[0227] Here, the recording medium 30A, which has been transported along the transport path 34 and has the toner image transferred to it by passing through the area where the photoreceptor 12 and the transfer member 20 face each other (transfer area 32A), is further transported along the transport path 34 by a transport member (not shown) to the installation position of the fixing device 26, where the toner image on the recording medium 30A is fixed.

[0228] The recording medium 30A, on which the image has been formed by fixing the toner image, is discharged to the outside of the image forming apparatus 10 by a plurality of transport members (not shown in the figure). The photoreceptor 12 is then discharged by the static elimination device 24 and then recharged to a charging potential by the charging device 15.

[0229] [Operation of the image forming apparatus] An example of the operation of the image forming apparatus 10 according to this embodiment will be described. Note that various operations of the image forming apparatus 10 are performed by a control program executed in the control device 36.

[0230] The image forming operation of the image forming apparatus 10 will be described. First, the surface of the photoreceptor 12 is charged by the charging device 15. The electrostatic image forming device 16 exposes the charged surface of the photoreceptor 12 based on image information. This forms an electrostatic image on the photoreceptor 12 corresponding to the image information. In the developing device 18, the electrostatic image formed on the surface of the photoreceptor 12 is developed with a developer containing toner. This forms a toner image on the surface of the photoreceptor 12. In the transfer device 31, the toner image formed on the surface of the photoreceptor 12 is transferred to the recording medium 30A. The toner image transferred to the recording medium 30A is fixed by the fuser device 26. Meanwhile, the surface of the photoreceptor 12 after the toner image has been transferred is cleaned by the cleaning blade 22A in the cleaning device 22, and then static electricity is removed by the static elimination device 24.

[0231] The configuration of the image forming apparatus described in this embodiment is merely an example, and it goes without saying that its configuration may be modified without departing from the spirit of this embodiment. [Examples]

[0232] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited in any way to these examples.

[0233] <Preparation of the electrophotographic photoconductor> [Preparation of silica particles] 100 parts by mass of untreated (hydrophilic) silica particles (product name: OX50, manufactured by Aerosil, volume average particle size: 40 nm) were mixed with 30 parts by mass of a trimethylsilane compound (1,1,1,3,3,3-hexamethyldisilazane (manufactured by Tokyo Chemical Industry Co., Ltd.)) as a hydrophobic treatment agent. The mixture was reacted for 24 hours, and then filtered to obtain hydrophobic silica particles. These were designated as silica particles (1). The condensation rate of these silica particles (1) was 93%.

[0234] [Fabrication of electrophotographic photoreceptor (A1)] - Preparation of the lower layer - Zinc oxide: (Average particle size 70nm: Manufactured by Teika Co., Ltd.: Specific surface area value 15m²) 2 100 parts by mass of (g) was mixed with 500 parts by mass of tetrahydrofuran and stirred. 1.3 parts by mass of silane coupling agent (KBM503: manufactured by Shin-Etsu Chemical Co., Ltd.) was added and the mixture was stirred for 2 hours. Subsequently, the tetrahydrofuran was removed by vacuum distillation, and the mixture was baked at 120°C for 3 hours to obtain zinc oxide surface-treated with silane coupling agent.

[0235] 110 parts by mass of the surface-treated zinc oxide (silane coupling agent surface-treated zinc oxide) was stirred and mixed with 500 parts by mass of tetrahydrofuran. A solution of 0.6 parts by mass of alizarin dissolved in 50 parts by mass of tetrahydrofuran was added, and the mixture was stirred at 50°C for 5 hours. Subsequently, the zinc oxide to which alizarin had been added was filtered off by vacuum filtration, and the mixture was further dried under vacuum at 60°C to obtain alizarin-added zinc oxide.

[0236] A mixture was obtained by mixing 60 parts by mass of alizarin-modified zinc oxide, 13.5 parts by mass of a curing agent (blocked isocyanate Sumijule 3175, manufactured by Sumitomo Bayern Urethanes), 15 parts by mass of butyral resin (Eslec BM-1, manufactured by Sekisui Chemical Co., Ltd.), and 85 parts by mass of methyl ethyl ketone. 38 parts by mass of this mixture was mixed with 25 parts by mass of methyl ethyl ketone, and the mixture was dispersed for 2 hours using a sand mill with 1 mmφ glass beads to obtain a dispersion.

[0237] To the obtained dispersion, 0.005 parts by mass of dioctyltin dilaurate and 40 parts by mass of silicone resin particles (Tospar 145, manufactured by Momentive Performance Materials) were added as catalysts to obtain a coating solution for forming an undercoat. This coating solution was applied by immersion coating onto an aluminum substrate with a diameter of 60 mm, a length of 357 mm, and a wall thickness of 1 mm, and dried and cured at 170°C for 40 minutes to obtain an undercoat with a thickness of 19 μm.

[0238] -Fabrication of a charge generation layer- A mixture consisting of 15 parts by mass of hydroxygallium phthalocyanine, which has diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.3°, 16.0°, 24.9°, and 28.0° in its X-ray diffraction spectrum using Cukα characteristic X-rays as a charge-generating material, 10 parts by mass of vinyl chloride / vinyl acetate copolymer (VMCH, manufactured by NUC Corporation) as a binder resin, and 200 parts by mass of n-butyl acetate was dispersed for 4 hours using glass beads with a diameter of 1 mmφ in a sand mill. To the obtained dispersion, 175 parts by mass of n-butyl acetate and 180 parts by mass of methyl ethyl ketone were added and stirred to obtain a coating solution for forming a charge-generating layer. This coating solution for forming a charge-generating layer was immersed and coated onto a base layer, and dried at room temperature (25°C) to form a charge-generating layer with a film thickness of 0.2 μm.

[0239] -Fabrication of a charge transport layer- 36 parts by mass of silica particles (1) were mixed with 250 parts by mass of tetrahydrofuran. While maintaining the liquid temperature at 20°C, 25 parts by mass of 4-(2,2-diphenylethyl)-4',4”-dimethyltriphenylamine as a charge transport material and 25 parts by mass of bisphenol Z type polycarbonate resin (viscosity average molecular weight: 30000) as a binder resin were added, and the mixture was stirred for 12 hours to obtain a coating solution for forming a charge transport layer.

[0240] This charge transport layer forming coating solution was applied onto the charge generation layer and dried at 135°C for 40 minutes to form a charge transport layer with a thickness of 30 μm, thereby obtaining an organic photoreceptor (1).

[0241] Through the above process, an organic photoreceptor (1) was obtained in which a base layer, a charge generation layer, and a charge transport layer were laminated on an aluminum substrate in that order.

[0242] -Formation of an inorganic oxide layer, which serves as a surface protective layer- Next, an inorganic oxide layer composed of hydrogen-containing gallium oxide was formed on the surface of the organic photoreceptor (1). This inorganic oxide layer was formed using a film deposition apparatus having the configuration shown in Figure 4.

[0243] First, the organic photoreceptor (1) was placed on the substrate support member 213 inside the deposition chamber 210 of the deposition apparatus, and the deposition chamber 210 was evacuated through the exhaust port 211 until the pressure reached 0.1 Pa. Next, 40% diluted He oxygen gas (flow rate 1.6 sccm) and hydrogen gas (flow rate 50 sccm) were introduced from the gas introduction tube 220 into the high-frequency discharge tube section 221, which is equipped with a flat plate electrode 219 with a diameter of 85 mm. A 13.56 MHz radio wave was set to an output of 150 W using the high-frequency power supply unit 218 and a matching circuit (not shown in Figure 4), and the tuner was matched to initiate a discharge from the flat plate electrode 219. The reflected wave at this time was 0 W. Next, trimethylgallium gas (flow rate 1.9 sccm) was introduced into the plasma diffusion section 217 in the deposition chamber 210 via the gas introduction pipe 215 and the shower nozzle 216. At this time, the reaction pressure in the deposition chamber 210, as measured by a Balatron vacuum gauge, was 5.3 Pa. In this state, the organic photoreceptor (1) was rotated at a speed of 500 rpm for 68 minutes to deposit a film, forming an inorganic oxide layer with a thickness of 1.5 μm on the surface of the charge transport layer of the organic photoreceptor (1). The surface roughness Ra on the outer surface of the inorganic oxide layer was 1.3 nm. Furthermore, the static friction coefficient μ of the inorganic oxide layer was 0.29.

[0244] The elemental composition ratio (oxygen / gallium) of oxygen to gallium in the inorganic oxide layer was 1.25.

[0245] Through the above process, an electrophotographic photoreceptor (A1) was obtained in which a base layer, a charge generation layer, a charge transport layer, and an inorganic surface layer were sequentially formed on a conductive substrate.

[0246] [Fabrication of electrophotographic photoreceptors (A2) to (A5)] Electrophotographic photoreceptors (A2) to (A5) were obtained in the same manner as electrophotographic photoreceptor (A1), except that the amount of silica particles (1) in the charge transport layer was changed as shown in Table 1.

[0247] [Fabrication of electrophotographic photoreceptors (CA1) to (CA3)] Electrophotographic photoreceptors (CA1) to (CA3) were obtained in the same manner as electrophotographic photoreceptor (A1), except that the amount of silica particles (1) in the charge transport layer and the viscosity-average molecular weight of the bisphenol Z type polycarbonate resin were appropriately changed as shown in Table 1, and an inorganic oxide layer was omitted.

[0248] <Preparing the cleaning blade> [Creating the cleaning blade (B1)] Adipic acid (HOOC-C4H8-COOH) and 1,4-butanediol were polymerized in a 1:1 molar ratio, and the process was carried out to ensure that the terminal ends were -OH, thereby obtaining a polyester polyol in which a linear diol (butanediol) with 4 carbon atoms was polymerized. The number-average molecular weight of the obtained polyester polyol was 2000. Next, a cleaning blade forming composition (B1) was prepared by reacting a mixture of 45 mol% polyester polyol as the high molecular weight polyol component, 55 mol% 1,4-butanediol (1,4-BD, chain extender) as the low molecular weight polyol, 18 mol% 4,4'-diphenylmethane diisocyanate (MDI, polyisocyanate, manufactured by Nippon Polyurethane Industries Co., Ltd., Myrionate MT) as the isocyanate, and 0.8 mol% trimethylolpropane (TMP, manufactured by Mitsubishi Gas Chemical Company, Inc.) as the crosslinking agent at 80°C for 2 hours under a nitrogen atmosphere. Next, the cleaning blade forming composition (B1) was poured into a centrifugal molding machine with the mold adjusted to 140°C. After curing at 100°C for 1 hour, it was heated to mature at 110°C for 24 hours. The cooled cured material was then cut to obtain a cleaning blade (B1) with a width of 8 mm and a thickness of 2 mm. The ratio (M100 / Re) of the obtained cleaning blade (B1) from 100% modulus (M100 [MPa]) to rebound modulus (Re [%]) was 0.33.

[0249] [Examples 1-7, Comparative Examples 1-5] The electrophotographic photoreceptors obtained in each example, along with the cleaning blades, were incorporated into a Versant 3100 Press (manufactured by Fujifilm Business Innovation Co., Ltd.) in the combinations shown in Table 1 to obtain the image forming apparatuses for Examples 1-7 and Comparative Examples 1-5.

[0250] <Evaluation 1: Wear and tear of the photoreceptor> Using the image forming apparatus obtained in each example, 40,000 50% halftone images were printed on A3-sized paper under low temperature and low humidity conditions (10°C, 15%RH). The film thickness on the surface of the photoreceptor was measured after printing 40,000 images. The difference between the film thickness after image printing and the film thickness measured before image printing was determined as the wear amount (μm). The obtained wear amount values ​​were evaluated according to the following criteria. The film thickness was measured at 10 locations using an optical interferometry film thickness gauge (Otsuka Electronics Co., Ltd., FE-3000), and the average value was used as the film thickness.

[0251] -Evaluation Criteria- A: The amount of wear is 0.1 μm or less. B: The amount of wear is greater than 0.1 μm and less than or equal to 1.0 μm. C: The amount of wear is greater than 1.0 μm and less than or equal to 2.5 μm. D: The amount of wear exceeds 2.5 μm.

[0252] <Rating 2: Image Quality Evaluation> Using the image forming apparatus obtained in each example, 100 blank images (image density 0%) were output, followed by 100 30% halftone images, and then 100 solid images (image density 100%). The 100th white image, the 100th 30% halftone image, and the 100th solid color image were visually inspected and evaluated according to the following criteria.

[0253] -Evaluation Criteria- A: No image quality defects were observed in any of the three images. B: At least one of the three images shows slight image quality defects (specifically, streaky image defects), but these are within acceptable limits. C: At least one of the three images has an unacceptable level of image quality defect.

[0254] [Table 1]

[0255] From the above results, it can be seen that the image forming apparatus of the example suppresses wear of the photoreceptor and further suppresses image quality degradation due to poor cleaning compared to the image forming apparatus of the comparative example. In Comparative Examples 1 and 3, chipping was observed in the cleaning blade after 40,000 prints in Evaluation 1. [Explanation of Symbols]

[0256] 10 Image forming apparatus 12 Photoreceptor 14 Charged member 15. Charging device 16 Electrostatic image forming device 18. Developing device 20 Transfer Member 22 Cleaning device 22A Cleaning Blade 24 Static eliminator 26 Fixing device 30A recording medium 31 Transfer device 36 Control device 101 Sublayer 102 Charge generation layer 103 Charge transport layer 104 Conductive support 105 Photosensitive layer 106 Surface protective layer 107A, 107B Electrophotographic photoreceptor (photoreceptor) 210 Deposition chamber 211 Exhaust port 212 Base Rotating Section 213 Base support member 214 Base 215 Gas inlet pipe 216 Shower Nozzle 217 Plasma Diffusion Section 218 High-frequency power supply unit 219 Flat electrode 220 Gas inlet pipe 221 High-frequency discharge tube section 222 High-Frequency Coil 223 Quartz tube

Claims

1. An electrophotographic photoreceptor having a photosensitive layer and a surface protective layer in that order on a conductive support, A charging means for charging the surface of the electrophotographic photoreceptor, A means for forming an electrostatic image on the surface of the charged electrophotographic photoreceptor, A developing means containing an electrostatic image developer including an electrostatic image developing toner, and developing the electrostatic image formed on the surface of the electrophotographic photoreceptor as a toner image using the electrostatic image developer, A transfer means for transferring the toner image formed on the surface of the electrophotographic photoreceptor to the surface of a recording medium, A cleaning means having a cleaning blade that contacts the surface of the electrophotographic photoreceptor and cleans the surface of the electrophotographic photoreceptor, Equipped with, When the cleaning blade is brought into contact with the surface of the electrophotographic photoreceptor, the contact angle WA is 8° or more and 14° or less, and the penetration depth is 0.5 mm or more and 1.2 mm. An image forming apparatus wherein the static friction coefficient μ of the surface protective layer of the electrophotographic photoreceptor, as measured using a sapphire needle, is 0.3 or less, and the difference Δ between the amount of strain at rest and the amount of strain during operation, measured at a position 1 mm from the tip of the side of the cleaning blade that contracts when in contact with the electrophotographic photoreceptor, is 65 μST or more and 90 μST or less.

2. The image forming apparatus according to claim 1, wherein the surface protective layer is a metal oxide layer containing a group 13 element and oxygen.

3. The image forming apparatus according to claim 2, wherein the metal oxide layer containing the group 13 element and oxygen is a metal oxide layer containing gallium oxide.

4. The image forming apparatus according to claim 3, wherein the surface roughness Ra of the metal oxide layer is 1 nm or more and 5 nm or less.

5. An electrophotographic photoreceptor having a photosensitive layer and a surface protective layer in that order on a conductive support, A cleaning means having a cleaning blade that contacts the surface of the electrophotographic photoreceptor and cleans the surface of the electrophotographic photoreceptor, Equipped with, When the cleaning blade is brought into contact with the surface of the electrophotographic photoreceptor, the contact angle WA is 8° or more and 14° or less, and the penetration depth is 0.5 mm or more and 1.2 mm. A process cartridge for attachment to and detachment from an image forming apparatus, wherein the static friction coefficient μ of the surface protective layer of the electrophotographic photoreceptor, as measured using a sapphire needle, is 0.3 or less, and the difference Δ between the static strain and the operating strain, measured at a position 1 mm from the tip of the side of the cleaning blade that contracts when in contact with the electrophotographic photoreceptor, is 65 μST or more and 90 μST or less.

Images