Electrophotographic photoreceptor, process cartridge, and image forming apparatus

Abstract

The invention discloses an electrophotographic photoreceptor, a process cartridge, and an image forming apparatus, the electrophotographic photoreceptor having a conductive substrate, a charge generation layer disposed on the conductive substrate, a charge transport layer disposed on the charge generation layer, and a protective layer disposed on the charge transport layer, the value of the ratio L / epsilon of the total thickness L ([mu] m) of the charge transport layer and the protective layer to the dielectric constant epsilon (F / m) in the thickness direction of the whole of the charge transport layer and the protective layer is from 3 to 6 (inclusive).

Description

Technical Field

[0001] The present invention relates to an electronic photographic photoreceptor, a processing box and an image forming device. Background Art

[0002] Japanese Patent Gazette No. 2005-300742 discloses an image forming device which does not have a charge removal unit, and is provided with an electronic photographic photoreceptor and an image forming unit including a charging, exposing and developing device along a transfer material conveying path, wherein the electronic photographic photoreceptor is charged by applying only a DC voltage to a charging component arranged in contact with the electronic photographic photoreceptor, and the colorant image developed on the electronic photographic photoreceptor is directly transferred to the conveyed transfer material, thereby forming an image, wherein the dark decay amount of the electronic photographic photoreceptor after one minute when the surface is charged to +500V under an environment of 23°C / 55% RH is less than 15V, and the film thickness d of the charge transport layer of the electronic photographic photoreceptor, the relative dielectric constant ε of the binder resin of the charge transport layer, and the absolute value V of the dark part potential of the photoreceptor are in the relationship of formula (1) d÷ε×V≥3000.

[0003] Japanese Patent Application Laid-Open No. 2016-142916 discloses an image forming apparatus comprising: an electrophotographic photoreceptor having a conductive substrate and a photosensitive layer provided on the conductive substrate, wherein the outermost layer is formed of a cured film of a composition containing a reactive charge transport material; a charging unit arranged in contact with or in proximity to the surface of the electrophotographic photoreceptor to charge the surface of the electrophotographic photoreceptor; an electrostatic latent image forming unit that forms an electrostatic latent image on the surface of the charged electrophotographic photoreceptor; and a developing unit. The developing unit accommodates a developer containing a colorant having colorant particles and inorganic particles with a volume average particle size of less than 1 μm, and develops the electrostatic latent image formed on the surface of the electrophotographic photoreceptor by the developer to form a colorant image; a transfer unit, which transfers the colorant image to the surface of the recording medium; and a cleaning unit, which has a cleaning scraper, which contacts the surface of the electrophotographic photoreceptor to clean the surface of the electrophotographic photoreceptor, and at least the contact portion with the electrophotographic photoreceptor is composed of a rubber modified portion that has been plasma-implanted.

[0004] Japanese Patent Application Laid-Open No. 2023-120986 discloses an electrophotographic photoreceptor comprising a conductive substrate having a wall thickness of 3 mm or greater, a photosensitive layer provided on the conductive substrate, and a surface protective layer provided on the photosensitive layer. The surface protective layer is a layer composed of a cured film of a composition comprising a reactive group-containing charge transport material having a reactive group and a charge-transporting skeleton in the same molecule, or a cured film of a composition comprising a non-reactive charge transport material and a reactive group-containing non-charge transport material having no charge-transporting skeleton but having reactive groups, wherein the ratio of the degree of cure of the surface on the conductive substrate side to the degree of cure of the surface on the peripheral surface side is 75% or greater.

[0005] Japanese Patent Application Laid-Open No. 2023-142267 discloses a process cartridge comprising: a photoreceptor having a conductive substrate, a photosensitive layer provided on the conductive substrate, and a protective layer provided on the photosensitive layer; and a roller-shaped charging member that contacts the photoreceptor to charge the photoreceptor. The charge required to charge the photoreceptor is 1.65 μC / (m 2 V) or above. Summary of the Invention

[0006] The object of the present invention is to provide an electrophotographic photoreceptor that is less likely to produce charge leakage (local charge leakage generated when the electrophotographic photoreceptor is charged) compared to an electrophotographic photoreceptor in which the ratio L / ε of the total thickness L (μm) of the charge transport layer and the protective layer to the dielectric constant ε (F / m) of the charge transport layer and the protective layer in the thickness direction is less than 3, and is less likely to produce blurring (a phenomenon in which colorant adheres to the non-image portion of the recording medium) when continuously forming images compared to an electrophotographic photoreceptor in which the ratio L / ε exceeds 6.

[0007] According to a first embodiment of the present invention, an electronic photographic photosensitive body is provided, comprising: a conductive substrate; a charge generating layer, the charge generating layer being arranged on the conductive substrate; a charge transport layer, the charge transport layer being arranged on the charge generating layer; and a protective layer, the protective layer being arranged on the charge transport layer, wherein the ratio L / ε of the total thickness L (μm) of the charge transport layer and the protective layer to the dielectric constant ε (F / m) of the charge transport layer and the protective layer as a whole in the thickness direction is greater than or equal to 3 and less than or equal to 6.

[0008] According to a second aspect of the present invention, in the electrophotographic photoreceptor according to the first aspect, the value of the ratio L / ε is 4.5 or more and 5.5 or less.

[0009] According to a third aspect of the present invention, in the electrophotographic photoreceptor according to the first or second aspect, the protective layer is a cured film or a crosslinked film of a composition containing a reactive charge transport material.

[0010] According to a fourth aspect of the present invention, in the electrophotographic photoreceptor according to any one of the first to third aspects, the total thickness L is 10 μm or more and 20 μm or less.

[0011] According to a fifth aspect of the present invention, in the electrophotographic photoreceptor according to any one of the first to fourth aspects, a ratio L2 / L1 of the thickness L2 of the protective layer to the thickness L1 of the charge transport layer is 0.1 to 1.

[0012] According to the sixth embodiment of the present invention, the electronic photographic photosensitive body involved in any one of the first to fifth embodiments is an electronic photographic photosensitive body for an image forming device, and the image forming device comprises: a charging device, which charges the surface of the electronic photographic photosensitive body and has a charging component in contact with the electronic photographic photosensitive body, and only applies a DC voltage to the charging component; and a static eliminating device, which irradiates the surface of the electronic photographic photosensitive body with static eliminating light to eliminate static after transferring the colorant image to the surface of the recording medium.

[0013] According to a seventh aspect of the present invention, there is provided a process cartridge including the electrophotographic photoreceptor according to any one of the first to fifth aspects, wherein the process cartridge is attachable to and detachable from an image forming apparatus.

[0014] According to an eighth aspect of the present invention, there is provided the process cartridge according to the seventh aspect, further comprising a static eliminator for irradiating the surface of the electrophotographic photoreceptor with static-eliminating light to eliminate static after the toner image is transferred to the surface of the recording medium.

[0015] According to the ninth aspect of the present invention, the processing box involved in the seventh or eighth aspect further includes a charging device, which charges the surface of the electrophotographic photosensitive body and has a charging component in contact with the electrophotographic photosensitive body, and the charging device applies only a DC voltage to the charging component.

[0016] According to the tenth embodiment of the present invention, there is provided an image forming device comprising: the electronic photographic photosensitive body according to any one of the first to fifth embodiments; a charging device for charging the surface of the electronic photographic photosensitive body; an electrostatic latent image forming device for forming an electrostatic latent image on the surface of the charged electronic photographic photosensitive body; a developing device for developing the electrostatic latent image formed on the surface of the electronic photographic photosensitive body using a developer containing a colorant to form a toner image; a transfer device for transferring the toner image to the surface of a recording medium; and a static eliminating device for irradiating the surface of the electronic photographic photosensitive body with static eliminating light for static elimination after transferring the toner image to the surface of the recording medium.

[0017] According to an eleventh aspect of the present invention, in the image forming apparatus according to the tenth aspect, the charging device includes a charging member in contact with the electrophotographic photoreceptor, and applies only a DC voltage to the charging member.

[0018] (Effect)

[0019] According to the first, third or sixth scheme, an electrophotographic photoreceptor is provided that is less likely to cause charging leakage than an electrophotographic photoreceptor having a ratio L / ε value of less than 3, and an electrophotographic photoreceptor is provided that is less likely to cause blurring when continuously forming images than an electrophotographic photoreceptor having a ratio L / ε value of more than 6.

[0020] According to the second embodiment, an electrophotographic photoreceptor is provided that is less likely to cause charge leakage than an electrophotographic photoreceptor having a ratio L / ε of less than 4.5, and an electrophotographic photoreceptor is provided that is less likely to cause blurring during continuous image formation than an electrophotographic photoreceptor having a ratio L / ε of more than 5.5.

[0021] According to the fourth embodiment, an electrophotographic photoreceptor is provided that is less likely to cause charge leakage than an electrophotographic photoreceptor in which the total thickness L of the charge transport layer and the protective layer is less than 10 μm, and an electrophotographic photoreceptor is provided that is less likely to cause blurring when continuously forming images than an electrophotographic photoreceptor in which the total thickness L of the charge transport layer and the protective layer exceeds 20 μm.

[0022] According to the fifth aspect, an electrophotographic photoreceptor is provided that is less likely to cause charge leakage than an electrophotographic photoreceptor having a ratio L2 / L1 of the thickness L2 of the protective layer to the thickness L1 of the charge transport layer of less than 0.1.

[0023] According to the seventh, eighth or ninth scheme, a processing box is provided, which is less likely to cause charging leakage than a processing box in which the ratio L / ε of the electronic photographic photosensitive body is less than 3, and a processing box is provided, which is less likely to cause blurring when continuously forming images than a processing box in which the ratio L / ε of the electronic photographic photosensitive body exceeds 6.

[0024] According to the tenth or eleventh embodiment, an image forming apparatus is provided that is less likely to cause charge leakage than an image forming apparatus in which the ratio L / ε of the electrophotographic photoreceptor is less than 3, and an image forming apparatus is provided that is less likely to cause blurring when continuously forming images than an image forming apparatus in which the ratio L / ε of the electrophotographic photoreceptor is greater than 6. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 is a partial cross-sectional view showing an example of the layer structure of the electrophotographic photoreceptor according to the present embodiment;

[0026] Figure 2 FIG. 1 is a schematic structural diagram showing an example of an image forming apparatus according to the present embodiment;

[0027] Figure 3 This is a schematic structural diagram showing another example of the image forming apparatus according to the present embodiment. DETAILED DESCRIPTION

[0028] The following describes embodiments of the present invention. These descriptions and examples illustrate the embodiments and do not limit the scope of the embodiments.

[0029] In the present invention, "A and / or B" is synonymous with "at least one of A and B." That is, "A and / or B" may mean only A, only B, or a combination of A and B.

[0030] In the present invention, a numerical range expressed using “to” indicates a range including the numerical values ​​described before and after “to” as the minimum value and the maximum value, respectively.

[0031] In the numerical range of recording in stages in the present invention, the upper limit or lower limit of recording in one numerical range can also be replaced by the upper limit or lower limit of the numerical range of recording in other stages. In addition, in the numerical range of recording in the present invention, the upper limit or lower limit of the numerical range can also be replaced by the value shown in the embodiment.

[0032] In the present invention, the term "process" includes not only independent processes but also processes that cannot be clearly distinguished from other processes as long as the purpose of the process can be achieved.

[0033] In the present invention, when the embodiments are described with reference to the drawings, the configuration of the embodiments is not limited to the configuration shown in the drawings. In addition, the sizes of the components in the drawings are conceptual sizes, and the relative relationship between the sizes of the components is not limited to this.

[0034] In the present invention, each component may also include multiple corresponding substances. In the present invention, when the amount of each component in the composition is mentioned, if multiple substances equivalent to each component are present in the composition, the amount of each component refers to the total amount of the multiple substances present in the composition, unless otherwise specified.

[0035] In the present invention, multiple types of particles corresponding to each component may be included. When multiple types of particles corresponding to each component are present in the composition, the particle size of each component refers to the value for the mixture of the multiple types of particles present in the composition unless otherwise specified.

[0036] In the present invention, when a compound is represented by a structural formula, the symbols (C and H) representing carbon atoms and hydrogen atoms in a hydrocarbon group and / or a hydrocarbon chain may be omitted.

[0037] In the present invention, unless otherwise specified, alkyl groups and alkylene groups include linear, branched, and cyclic groups.

[0038] In the present invention, hydrogen atoms in groups such as organic groups, aromatic rings, linking groups, alkyl groups, alkylene groups, aryl groups, aralkyl groups, alkoxy groups, and aryloxy groups may be replaced by halogen atoms.

[0039] In the present invention, “(meth)acrylic acid” includes both acrylic acid and methacrylic acid, and “(meth)acrylate” includes both acrylic acid and methacrylate.

[0040] In the present invention, the "constituent unit" of a copolymer or resin is synonymous with a monomer unit.

[0041] In the present invention, the “axial direction” of the electrophotographic photoreceptor refers to the direction in which the rotation axis of the electrophotographic photoreceptor extends, and the “circumferential direction” of the electrophotographic photoreceptor refers to the rotation direction of the electrophotographic photoreceptor.

[0042] <Electrophotographic photoreceptor>

[0043] The electrophotographic photoreceptor of this embodiment (hereinafter also referred to as a "photoreceptor") comprises a conductive substrate, a charge generating layer disposed on the conductive substrate, a charge transport layer disposed on the charge generating layer, and a protective layer disposed on the charge transport layer. The charge generating layer and the charge transport layer are photosensitive layers (so-called laminated photosensitive layers or functionally separated photosensitive layers).

[0044] The photoreceptor of this embodiment may further include layers other than the charge generating layer, the charge transport layer, and the protective layer (for example, an undercoat layer, an intermediate layer).

[0045] Figure 1 This is a partial cross-sectional view schematically showing an example of the layer structure of the photoreceptor according to this embodiment. Figure 1 The photoreceptor 10A shown has a structure in which an undercoat layer 2, a charge generating layer 3, a charge transport layer 4, and a protective layer 6 are sequentially stacked on a conductive substrate 1. The charge generating layer 3 and the charge transport layer 4 constitute a photosensitive layer 5. The photoreceptor 10A may also have an intermediate layer (not shown) between the undercoat layer 2 and the charge generating layer 3. The undercoat layer 2 may or may not be present.

[0046] In the photoreceptor of this embodiment, the ratio (L / ε) of the total thickness L (μm) of the charge transport layer and protective layer to the dielectric constant ε (F / m) of the charge transport layer and protective layer in the thickness direction is 3 or more and 6 or less. The photoreceptor of this embodiment is less susceptible to charge leakage (localized charge leakage that occurs when the photoreceptor is charged) and is less susceptible to fogging (a phenomenon in which toner adheres to non-image areas of the recording medium) during continuous image formation. The mechanism for this is speculated as follows.

[0047] Blurring can sometimes occur when continuously forming images using an image forming apparatus equipped with a photoreceptor having a protective layer on its surface. This phenomenon is particularly common in image forming apparatuses equipped with a static elimination device that irradiates the photoreceptor surface with static elimination light. This is presumably because the charge generated in the charge generation layer by irradiation with static elimination light gradually accumulates in the charge transport layer and protective layer, causing the surface potential of the photoreceptor to gradually decrease.

[0048] The above phenomenon is more likely to occur in image forming apparatuses equipped with a charging device that has a charging member in contact with the photoreceptor and applies only a DC voltage to the charging member (hereinafter referred to as a "contact DC charging device"). This is presumably because when charge generated in the charge generation layer by irradiation with neutralizing light accumulates in the charge transport layer and protective layer, the accumulated charge is transferred to the photoreceptor surface by the charging of the contact DC charging device, thereby easily lowering the surface potential of the photoreceptor.

[0049] The photosensitive body of this embodiment suppresses the accumulation of charge in the charge transport layer and the protective layer by maintaining a balance between the total thickness L (μm) of the charge transport layer and the protective layer and the dielectric constant ε (F / m) in the thickness direction of the charge transport layer and the protective layer as a whole. As a result, the decrease in the surface potential of the photosensitive body and the generation of blurring are suppressed.

[0050] In the photoreceptor of this embodiment, the ratio L / ε of the total thickness L (μm) of the charge transport layer and the protective layer to the dielectric constant ε (F / m) of the charge transport layer and the protective layer in the thickness direction is 3 or more and 6 or less.

[0051] When the ratio L / ε exceeds 6, the total thickness L of the charge transport layer and the protective layer is too thick compared to the value of the dielectric constant ε, and the charges generated in the charge generating layer due to the irradiation of the neutralizing light are easily accumulated in the charge transport layer and the protective layer. As a result, the surface potential of the photosensitive body decreases, causing blurring.

[0052] When the ratio L / ε is less than 3, the total thickness L of the charge transport layer and the protective layer is thin, and local charge leakage (charge leakage) is likely to occur when charging the photoreceptor.

[0053] In order to suppress the above phenomenon, the value of the ratio L / ε is 3 or more and 6 or less, more preferably 4 or more and 6 or less, further preferably 4.5 or more and 5.8 or less, and further preferably 4.5 or more and 5.5 or less.

[0054] The total thickness L of the charge transport layer and the protective layer of the photoreceptor of this embodiment is preferably 10 μm or more and 20 μm or less.

[0055] When the total thickness L is 20 μm or less, the charges generated in the charge generating layer by irradiation with static-eliminating light are less likely to accumulate in the charge transport layer and the protective layer. From this viewpoint, the total thickness L is more preferably 18 μm or less.

[0056] When the total thickness L is 10 μm or more, charge leakage is less likely to occur. From this viewpoint, the total thickness L is more preferably 12 μm or more.

[0057] In the photoreceptor of this embodiment, the value of the ratio L2 / L1 of the thickness L2 of the protective layer to the thickness L1 of the charge transport layer is preferably 0.1 or more and 1 or less.

[0058] When the ratio L2 / L1 is 1 or less, the charge transport layer is not too thin, which is preferable in terms of the electrical properties of the photoreceptor. From this viewpoint, the ratio L2 / L1 is more preferably 0.9 or less, and even more preferably 0.8 or less.

[0059] When the ratio L2 / L1 is 0.1 or greater, charge leakage is less likely to occur. From this viewpoint, the total thickness L is more preferably 0.3 or greater, and even more preferably 0.5 or greater.

[0060] In this embodiment, the thickness L1 of the charge transport layer, the thickness L2 of the protective layer, and the total thickness L of the charge transport layer and the protective layer have the following physical property values.

[0061] The charge transport layer thickness L1 is obtained by measuring the thickness of the charge transport layer at 10 equal locations in the axial direction of the photoreceptor and at 40 locations equally divided into four portions (90° intervals) in the circumferential direction of the photoreceptor using an eddy current thickness meter, and taking the arithmetic average.

[0062] The thickness L2 of the protective layer is obtained by measuring the thickness of the protective layer at 10 equal locations in the axial direction of the photoreceptor and at 40 locations in four equal locations (90° intervals) in the circumferential direction of the photoreceptor using an eddy current thickness meter, and taking the arithmetic average.

[0063] The total thickness L of the charge transport layer and the protective layer is the value obtained by adding the layer thickness L1 and the layer thickness L2.

[0064] The method for measuring the dielectric constant ε (F / m) in the thickness direction of the entire charge transport layer and protective layer is as follows.

[0065] - Preparation of Samples for Capacitance Measurement -

[0066] The photoreceptor is cut near the surface using a single-edged razor or other similar blade, and the charge transport layer and protective layer are peeled off integrally using pliers. Gold electrodes are formed on both sides of the peeled film (the laminated film of the charge transport layer and protective layer) by vacuum deposition or sputtering to obtain a sample for capacitance measurement.

[0067] -Capacitance measurement using the AC impedance method-

[0068] The measuring apparatus and measuring conditions are as follows.

[0069] ·Power supply: SI1287 electrochemical interface (Solartron Analytical)

[0070] Amperemeter: SI1260 impedance / gain phase analyzer (Solartron Analytical)

[0071] Current amplifier: 1296dielectric interface (Solartron Analytical)

[0072] AC voltage: 1Vp-p

[0073] ·Measurement frequency: from 1 MHz to 1 mHz, applied from the high frequency side.

[0074] Measurement environment: temperature 22°C, relative humidity 55%

[0075] The sample was sandwiched between an aluminum plate (cathode) and a gold electrode (anode). The AC impedance was measured using the aforementioned measurement equipment and conditions. The Cole-Cole plot was fitted to an RC parallel equivalent circuit to determine the capacitance. The dielectric constant ε was calculated using the formula: Capacitance C = Dielectric Constant ε × S / L (S: electrode area, L: sample thickness).

[0076] The dielectric constant ε (F / m) in the thickness direction of the charge transport layer and the protective layer as a whole is preferably 3.0 to 4.0, more preferably 3.1 to 3.8, and even more preferably 3.2 to 3.5.

[0077] The value of the dielectric constant ε (F / m) in the thickness direction of the charge transport layer is preferably 2.5 or more and 3.8 or less, more preferably 2.8 or more and 3.5 or less, and even more preferably 3.0 or more and 3.3 or less.

[0078] The dielectric constant ε (F / m) of the protective layer in the thickness direction is preferably 3.2 or more and 4.5 or less, more preferably 3.4 or more and 4.2 or less, and even more preferably 3.6 or more and 4.0 or less.

[0079] The method for measuring the dielectric constant ε in the thickness direction of the charge transport layer and the dielectric constant ε in the thickness direction of the protective layer is the same as the method for measuring the dielectric constant ε in the thickness direction of the charge transport layer and the protective layer as a whole.

[0080] The dielectric constant ε (F / m) in the thickness direction of the charge transport layer and the protective layer can be controlled by the content of the charge transport material contained in each layer. The higher the content of the charge transport material, the smaller the dielectric constant ε.

[0081] The photosensitive body of this embodiment is suitable as a photosensitive body for an image forming device, wherein the image forming device has a charging device and a neutralizing device, wherein the charging device has a charging component in contact with the photosensitive body and only a DC voltage is applied to the charging component, and the neutralizing device irradiates the surface of the photosensitive body with neutralizing light to neutralize the surface of the photosensitive body after transferring the colorant image to the surface of the recording medium.

[0082] Next, each layer of the electrophotographic photoreceptor according to this embodiment will be described in detail.

[0083] [Conductive substrate]

[0084] Examples of conductive substrates include metal plates, metal drums, and metal belts containing metals (aluminum, copper, zinc, chromium, nickel, molybdenum, vanadium, indium, gold, platinum, etc.) or alloys (stainless steel, etc.). Furthermore, examples of conductive substrates include paper, resin films, and belts coated, vapor-deposited, or laminated with conductive compounds (e.g., conductive polymers, indium oxide, etc.), metals (e.g., aluminum, palladium, gold, etc.), or alloys. Here, "conductive" means a volume resistivity of less than 1×10 13 Ω·cm.

[0085] When using electrophotographic photoreceptors in laser printers, the surface of the conductive substrate is preferably roughened to a centerline average roughness Ra of 0.04 μm to 0.5 μm to suppress interference fringes generated during laser irradiation. When using non-interfering light as the light source, roughening is not particularly necessary to prevent interference fringes. However, roughening can help extend the life of the printer by suppressing defects caused by irregularities on the conductive substrate surface.

[0086] Examples of methods for roughening the surface include wet honing in which an abrasive is suspended in water and sprayed onto the conductive substrate; centerless grinding in which the conductive substrate is pressed against a rotating grindstone and continuously ground; and anodizing.

[0087] As a method for roughening the surface, the following method can be cited: instead of roughening the surface of the conductive substrate, conductive or semiconductive powder is dispersed in a resin to form a layer on the surface of the conductive substrate, and the surface is roughened by the particles dispersed in the layer.

[0088] The roughening treatment based on anodizing is to form an oxide film on the surface of the conductive substrate by carrying out anodizing in an electrolyte solution with a conductive substrate made of metal (such as aluminum) as an anode. As an electrolyte solution, for example, sulfuric acid solution, oxalic acid solution etc. can be enumerated. However, the porous anodized film formed by anodizing is chemically active under the original state, easily contaminated, and the resistance change caused by the environment is also large. Thus, preferably, the porous anodized film is carried out to a sealing process, in which the micropores of the oxide film are blocked by the volume expansion caused by hydration reaction in pressurized steam or boiling water (metal salts such as nickel can be added), and the oxide film is changed into a more stable hydrated oxide.

[0089] The thickness of the anodic oxide film is preferably 0.3 μm to 15 μm, for example. When the film thickness is within the above range, the film tends to exhibit a barrier property against injection and tends to suppress an increase in residual potential caused by repeated use.

[0090] The conductive substrate may be subjected to treatment using an acidic treatment liquid or boehmite treatment.

[0091] The treatment using an acidic treatment solution is carried out, for example, as follows. First, an acidic treatment solution containing phosphoric acid, chromic acid, and hydrofluoric acid is prepared. As for the mixing ratio of phosphoric acid, chromic acid, and hydrofluoric acid in the acidic treatment solution, for example, phosphoric acid is in the range of 10% by mass to 11% by mass, chromic acid is in the range of 3% by mass to 5% by mass, and hydrofluoric acid is in the range of 0.5% by mass to 2% by mass, and the overall concentration of these acids is preferably in the range of 13.5% by mass to 18% by mass. The treatment temperature is preferably, for example, 42°C to 48°C. The film thickness of the coating is preferably 0.3 μm to 15 μm.

[0092] Boehmite treatment can be performed, for example, by immersing the substrate in pure water at 90°C to 100°C for 5 to 60 minutes, or by contacting the substrate with heated steam at 90°C to 120°C for 5 to 60 minutes. The coating preferably has a thickness of 0.1 μm to 5 μm. Alternatively, the substrate may be further anodized using an electrolyte solution with low coating solubility, such as adipic acid, boric acid, borates, phosphates, phthalates, maleates, benzoates, tartrates, or citrates.

[0093] [Base coat]

[0094] The undercoat layer is, for example, a layer containing inorganic particles and a binder resin.

[0095] Examples of the inorganic particles include particles having a powder resistance (volume resistivity) of 1×10 2 Ω·cm or more and 1×10 11 Inorganic particles with a particle size of Ω·cm or less.

[0096] Among them, as the inorganic particles having the above-mentioned resistance value, for example, metal oxide particles such as tin oxide particles, titanium dioxide particles, zinc oxide particles, and zirconium oxide particles are preferred, and zinc oxide particles are particularly preferred.

[0097] The specific surface area of ​​the inorganic particles by the BET method is preferably, for example, 10 m 2 / g or above.

[0098] The volume average particle size of the inorganic particles is preferably, for example, 50 nm or more and 2000 nm or less (preferably 60 nm or more and 1000 nm or less).

[0099] The content of the inorganic particles is, for example, preferably 10% by mass or more and 80% by mass or less, and more preferably 40% by mass or more and 80% by mass or less, relative to the binder resin.

[0100] The inorganic particles may be surface-treated. Inorganic particles having different surface treatments or two or more inorganic particles having different particle sizes may be mixed and used.

[0101] Examples of the surface treatment agent include silane coupling agents, titanate coupling agents, aluminum coupling agents, surfactants, etc. In particular, silane coupling agents are preferred, and silane coupling agents having an amino group are more preferred.

[0102] Examples of the silane coupling agent 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.

[0103] Silane coupling agents can also be used in combination of two or more. For example, a silane coupling agent having an amino group and other silane coupling agents can also be used in combination. As other silane coupling agents, for example, vinyl trimethoxysilane, 3-methacryloxypropyl-tris (2-methoxyethoxy) silane, 2- (3,4-epoxycyclohexyl) ethyl trimethoxysilane, 3-glycidoxypropyl trimethoxysilane, vinyl triacetoxysilane, 3-mercaptopropyl trimethoxysilane, 3-aminopropyl triethoxysilane, N-2- (aminoethyl) -3-aminopropyl trimethoxysilane, N-2- (aminoethyl) -3-aminopropyl methyl dimethoxysilane, N, N-bis (2-hydroxyethyl) -3-aminopropyl triethoxysilane, 3-chloropropyl trimethoxysilane, etc. can be mentioned, but it is not limited thereto.

[0104] The surface treatment method using the surface treatment agent may be any method as long as it is a known method, and may be either a dry method or a wet method.

[0105] The treatment amount of the surface treatment agent is preferably, for example, 0.5% by mass or more and 10% by mass or less relative to the inorganic particles.

[0106] Here, from the viewpoint of improving the long-term stability of electrical characteristics and carrier blocking properties, the undercoat layer preferably contains an electron acceptor compound (acceptor compound) together with the inorganic particles.

[0107] Examples of electron acceptor compounds include quinone compounds such as tetrachlorobenzoquinone and tetrabromobenzoquinone; tetracyanoquinolmethane 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-tert-butylphenyl)-1,3,4-oxadiazole, 2,5-bis(4-naphthyl)-1,3,4-oxadiazole and 2,5-bis(4-diethylaminophenyl)-1,3,4-oxadiazole; xanthone compounds; thiophene compounds; diphenoquinone compounds such as 3,3',5,5'-tetra-tert-butyldiphenoquinone; and benzophenone compounds.

[0108] As the electron acceptor compound, a compound having an anthraquinone structure is particularly preferred. Examples of the compound having an anthraquinone structure include hydroxyanthraquinone compounds, aminoanthraquinone compounds, and aminohydroxyanthraquinone compounds. Specifically, examples include anthraquinone, alizarin, quinizarin, anthrarutin, and purpurin.

[0109] The electron acceptor compound may be contained in the undercoat layer in a dispersed state together with the inorganic particles, or may be contained in a state of being attached to the surface of the inorganic particles.

[0110] Examples of a method for attaching the electron acceptor compound to the surface of the inorganic particles include a dry method and a wet method.

[0111] The dry method, for example, involves adding an electron acceptor compound directly or dissolved in an organic solvent while stirring the inorganic particles using a mixer with high shear force, spraying the electron acceptor compound with dry air or nitrogen to adhere the electron acceptor compound to the surface of the inorganic particles. The dropwise addition or spraying of the electron acceptor compound is preferably performed at a temperature below the boiling point of the solvent. Alternatively, the dropwise addition or spraying of the electron acceptor compound may be followed by sintering at a temperature above 100°C. The sintering process is not particularly limited, as long as the temperature and time required to achieve electrophotographic properties are sufficient.

[0112] The wet method is, for example, a method in which inorganic particles are dispersed in a solvent using stirring, ultrasonic waves, a sand mill, a grinder, a ball mill, etc., while adding an electron acceptor compound, stirring or dispersing, and then removing the solvent to attach the electron acceptor compound to the surface of the inorganic particles. The solvent removal method is, for example, distillation removal by filtration or distillation. After the solvent is removed, sintering may be further performed at a temperature above 100°C. There are no particular restrictions on sintering, as long as the temperature and time are such that electronic photographic characteristics can be obtained. In the wet method, the water content of the inorganic particles may also be removed before adding the electron acceptor compound. Examples thereof include a method of removing the water content in the solvent while stirring and heating, and a method of removing the water content by azeotropic reaction with the solvent.

[0113] The electron acceptor compound may be attached before or after the inorganic particles are subjected to surface treatment using a surface treatment agent, or may be attached simultaneously with the surface treatment using a surface treatment agent.

[0114] The content of the electron acceptor compound is, for example, preferably 0.01% by mass or more and 20% by mass or less, and more preferably 0.01% by mass or more and 10% by mass or less, relative to the inorganic particles.

[0115] Examples of the binder resin used for the primer layer include acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, unsaturated polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-modified alkyd resins, urea-formaldehyde resins, phenol resins, phenol-formaldehyde resins, melamine resins, polyurethane resins, alkyd resins, epoxy resins, and other known polymer compounds; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; alkoxytitanium compounds; organic titanium compounds; and silane coupling agents.

[0116] Examples of the binder resin used for the primer layer include charge transporting resins having a charge transporting group and conductive resins (eg, polyaniline).

[0117] Among them, the binder resin used as the primer layer is preferably a resin that is insoluble in the coating solvent of the upper layer, and is particularly preferably a thermosetting resin such as urea-formaldehyde resin, phenol resin, phenol-formaldehyde resin, melamine resin, polyurethane resin, unsaturated polyester resin, alkyd resin, epoxy resin; or a resin obtained by reacting at least one resin selected from the group consisting of polyamide resin, polyester resin, polyether resin, methacrylic resin, acrylic resin, polyvinyl alcohol resin and polyvinyl acetal resin with a curing agent.

[0118] When two or more of these binder resins are used in combination, the mixing ratio thereof is set as needed.

[0119] The undercoat layer may contain various additives for the purpose of improving electrical characteristics, enhancing environmental stability, and improving image quality.

[0120] Examples of additives include known materials such as polycyclic condensation-based and azo-based electron transport pigments, zirconium chelate compounds, titanium chelate compounds, aluminum chelate compounds, alkoxytitanium compounds, organic titanium compounds, and silane coupling agents. Silane coupling agents are used for surface treatment of inorganic particles as described above, but can also be added to the primer as an additive.

[0121] Examples of the silane coupling agent used as an additive include vinyltrimethoxysilane, 3-methacryloxypropyl-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.

[0122] Examples of the zirconium chelate compound include zirconium butoxide, zirconium ethyl acetoacetate, zirconium triethanolamine, zirconium acetylacetonate butoxide, zirconium ethyl acetoacetate butoxide, zirconium acetate, zirconium oxalate, zirconium lactate, zirconium phosphonate, zirconium octylate, zirconium naphthenate, zirconium laurate, zirconium stearate, zirconium isostearate, zirconium methacrylate butoxide, zirconium stearate butoxide, and zirconium isostearate butoxide.

[0123] Examples of the titanium chelate compound include tetraisopropyl titanate, tetra-n-butyl titanate, butyl titanate dimer, tetra(2-ethylhexyl) titanate, titanium acetylacetonate, titanium polyacetylacetonate, titanium octyl glycolate, titanium ammonium lactate, titanium lactate, titanium ethyl lactate, triethanolamine titanium, and polyhydroxytitanium stearate.

[0124] Examples of the aluminum chelate compound include aluminum isopropoxide, aluminum diisopropoxide monobutoxide, aluminum butyrate, aluminum ethylacetoacetate diisopropoxide, and aluminum tris(ethylacetoacetate).

[0125] These additives may be used alone or as a mixture or polycondensate of a plurality of compounds.

[0126] The Vickers hardness of the primer layer is preferably 35 or higher.

[0127] To suppress moire patterns, the surface roughness (ten-point average roughness) of the undercoat layer is preferably adjusted to be from 1 / (4n) to 1 / 2 of the wavelength λ of the exposure laser used (n is the refractive index of the upper layer).

[0128] To adjust the surface roughness, resin particles or the like may be added to the primer layer. Examples of the resin particles include silicone resin particles and cross-linked polymethyl methacrylate resin particles. Furthermore, to adjust the surface roughness, the primer layer surface may be ground. Examples of polishing methods include soft leather polishing, sandblasting, wet honing, and grinding.

[0129] The formation of the undercoat layer is not particularly limited and can be performed using a known formation method, for example, by forming a coating film of an undercoat layer-forming coating liquid obtained by adding the above-mentioned components to a solvent, drying the coating film, and heating as needed.

[0130] Examples of the solvent used for preparing the coating liquid for forming the undercoat layer include well-known organic solvents such as alcohol solvents, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, ketone solvents, ketone alcohol solvents, ether solvents, and ester solvents.

[0131] Specific examples of these solvents include common organic solvents such as methanol, ethanol, n-propanol, isopropanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, ethyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene dichloride, chloroform, chlorobenzene, and toluene.

[0132] Examples of the method for dispersing the inorganic particles when preparing the coating liquid for forming an undercoat layer include known methods such as a roll mill, a ball mill, a vibration ball mill, an attritor, a sand mill, a colloid mill, and a paint sieve.

[0133] Examples of a method for applying the coating liquid for forming an undercoat layer onto a conductive substrate include common methods such as doctor blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0134] The thickness of the primer layer is preferably set to, for example, 15 μm or more, and more preferably set to be within the range of 20 μm or more and 50 μm or less.

[0135] [Middle layer]

[0136] An intermediate layer may be provided between the undercoat layer and the photosensitive layer.

[0137] The intermediate layer is, for example, a layer containing a resin. Examples of the resin used in the intermediate layer include polymer compounds such as acetal resins (e.g., polyvinyl butyral), polyvinyl alcohol resins, polyvinyl acetal resins, casein resins, polyamide resins, cellulose resins, gelatin, polyurethane resins, polyester resins, methacrylic resins, acrylic resins, polyvinyl chloride resins, polyvinyl acetate resins, vinyl chloride-vinyl acetate-maleic anhydride resins, silicone resins, silicone-modified alkyd resins, phenol-formaldehyde resins, and melamine resins.

[0138] The intermediate layer may also be a layer containing an organic metal compound. Examples of the organic metal compound used in the intermediate layer include organic metal compounds containing metal atoms such as zirconium, titanium, aluminum, manganese, and silicon.

[0139] The compounds used in the intermediate layer may be used alone or as a mixture or polycondensate of a plurality of compounds.

[0140] Among them, the intermediate layer is preferably a layer containing an organometallic compound containing zirconium atoms or silicon atoms.

[0141] The intermediate layer can be formed without particular limitation and can be formed using a known formation method, for example, by forming a coating film of an intermediate layer-forming coating liquid obtained by adding the above-mentioned components to a solvent, drying the coating film, and heating as needed.

[0142] As a coating method for forming the intermediate layer, a common method such as dip coating, push-up coating, wire bar coating, spray coating, blade coating, air knife coating, curtain coating, etc. is used.

[0143] The thickness of the intermediate layer is preferably set within a range of, for example, 0.1 μm to 3 μm. The intermediate layer can also be used as a primer layer.

[0144] [Charge Generation Layer]

[0145] The charge generating layer is, for example, a layer comprising a charge generating material and a binder resin. Alternatively, the charge generating layer may be a vapor-deposited layer of the charge generating material. This vapor-deposited layer of the charge generating material is suitable for use with non-interfering light sources such as LEDs (Light Emitting Diodes) and organic EL (Electroluminescence) image arrays.

[0146] Examples of the charge generating material include azo pigments such as disazo and trisazo; ring-condensed aromatic pigments such as dibromoanthanthrone; perylene pigments; pyrrolopyrrole pigments; phthalocyanine pigments; zinc oxide; and trigonal selenium.

[0147] Among them, in order to cope with near-infrared laser exposure, metal phthalocyanine pigments or metal-free phthalocyanine pigments are preferably used as charge generating materials. Specifically, for example, hydroxygallium phthalocyanine, chlorogallium phthalocyanine, dichlorotin phthalocyanine, and titanyl phthalocyanine are more preferred.

[0148] On the other hand, in order to cope with near-ultraviolet laser exposure, preferred charge generating materials include cyclic aromatic pigments such as dibromoanthrone and anthrone, thioindigo pigments, tetraazaporphyrin compounds, zinc oxide, trigonal selenium, and disazo pigments.

[0149] The above-mentioned charge generation material can also be used when using a non-interfering light source such as an LED or an organic EL array whose central wavelength of light emission is from 450 nm to 780 nm.

[0150] When using n-type semiconductors such as cyclic aromatic pigments, perylene pigments, and azo pigments as charge-generating materials, dark current generation is less likely to occur, and image defects known as black spots can be suppressed even in thin films. The n-type is determined by the polarity of the photocurrent flowing using the commonly used time-of-flight method, with those that more readily carry electrons as carriers than holes being designated n-type.

[0151] The binder resin used in the charge generating layer can be selected from a wide range of insulating resins. Alternatively, the binder resin can be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane.

[0152] Examples of the binder resin include polyvinyl butyral resin, polyarylate resin (a polycondensate of bisphenols and aromatic dicarboxylic acids), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin, polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, polyurethane resin, epoxy resin, casein, polyvinyl alcohol resin, and polyvinyl pyrrolidone resin. Here, "insulating property" refers to a volume resistivity of 1×10 13 Ω·cm or more.

[0153] These binder resins are used alone or in combination of two or more.

[0154] The mixing ratio of the charge generating material and the binder resin is preferably in the range of 10:1 to 1:10 in terms of mass ratio.

[0155] The charge generating layer may contain other known additives.

[0156] The charge generating layer can be formed without particular limitation and can be formed using a known method, for example, by forming a film of a charge generating layer-forming coating liquid obtained by adding the above-mentioned components to a solvent, drying the film, and optionally heating it. The charge generating layer can also be formed by vapor deposition of the charge generating material. Formation of the charge generating layer by vapor deposition is particularly suitable when using cyclic aromatic pigments or perylene pigments as the charge generating material.

[0157] Examples of the solvent used for preparing the charge generating layer-forming coating solution include methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene dichloride, chloroform, chlorobenzene, and toluene. These solvents may be used alone or in combination of two or more.

[0158] As a method for dispersing particles (e.g., charge generating material) in the charge generating layer-forming coating liquid, for example, a medium disperser such as a ball mill, a vibrating ball mill, an attritor, a sand mill, or a horizontal sand mill, or a medium-free disperser such as a stirrer, an ultrasonic disperser, a roll mill, or a high-pressure homogenizer can be used. Examples of high-pressure homogenizers include a collision method in which the dispersion is dispersed by liquid-liquid collision or liquid-wall collision under high pressure, and a penetration method in which the dispersion is dispersed by penetrating fine flow paths under high pressure.

[0159] During the dispersion, it is effective to set the average particle size of the charge generating material in the charge generating layer-forming coating liquid to 0.5 μm or less, preferably 0.3 μm or less, and more preferably 0.15 μm or less.

[0160] Examples of methods for applying the charge generating layer-forming coating liquid onto the undercoat layer (or intermediate layer) include common methods such as doctor blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0161] The thickness of the charge generating layer is preferably set to, for example, 0.1 μm or more and 5.0 μm or less, and more preferably set to be within the range of 0.2 μm or more and 2.0 μm or less.

[0162] [Charge transport layer]

[0163] The charge transport layer is, for example, a layer containing a charge transport material and a binder resin. The charge transport layer may also be a layer containing a polymer charge transport material.

[0164] Examples of charge transport materials include electron transport compounds such as quinone compounds such as p-benzoquinone, tetrachlorobenzoquinone, tetrabromobenzoquinone, and anthraquinone; tetracyanoquinolmethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanoethylene compounds; and vinyl compounds. Other examples of charge transport materials include hole transport compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted vinyl 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.

[0165] As the charge transport material, from the viewpoint of charge mobility, a triarylamine derivative represented by the following structural formula (a-1) and a benzidine derivative represented by the following structural formula (a-2) are preferred.

[0166]

[0167] In the structural formula (a-1), Ar T1 、Ar T2 , and Ar T3 Each independently represents a substituted or unsubstituted aryl, -C6H4-C(R T4 )=C(R T5 )(R T6 ), or -C6H4-CH=CH-CH=C(R T7 )(R T8 ). R T4 、R T5 、R T6 、R T7 , and R T8 Each independently represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group.

[0168] Examples of substituents for the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Examples of substituents for the above groups include substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms.

[0169]

[0170] In the structural formula (a-2), R T91 and R T92 R each 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 T112Each independently represents 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, -C(R T12 )=C(R T13 )(R T14 ), or -CH=CH-CH=C(R T15 )(R T16 ), R T12 、R T13 、R T14 、R T15 and R T16 Each 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 of 0 or more and 2 or less.

[0171] Examples of substituents for the above groups include halogen atoms, alkyl groups having 1 to 5 carbon atoms, and alkoxy groups having 1 to 5 carbon atoms. Examples of substituents for the above groups include substituted amino groups substituted with alkyl groups having 1 to 3 carbon atoms.

[0172] From the viewpoint of charge mobility, it is preferred that the triarylamine derivative represented by the structural formula (a-1) and the benzidine derivative represented by the structural formula (a-2) have "-C6H4-CH=CH-CH=C(R T7 )(R T8 )" and triarylamine derivatives having "-CH=CH-CH=C(R T15 )(R T16 )" benzidine derivatives.

[0173] Examples of polymeric charge transport materials include known materials having charge transport properties such as poly-N-vinylcarbazole and polysilane. Among these, polyester-based polymeric charge transport materials are preferred. The polymeric charge transport material may be used alone or in combination with a binder resin.

[0174] The binder resin used in the charge transport layer can 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-modified alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinyl carbazole, polysilane, etc. These binder resins are used alone or in combination. The blending ratio of the charge transport material and the binder resin is preferably 10:1 to 1:5 in terms of mass ratio.

[0175] From the perspective of durability of the charge transport layer, the binder resin is preferably at least one selected from the group consisting of polycarbonate resins and polyarylate resins. The polycarbonate resin and the polyarylate resin may be used alone or as a mixture thereof.

[0176] The charge transport layer may contain other known additives. Examples of the additives include antioxidants, leveling agents, defoaming agents, fillers, and viscosity modifiers.

[0177] The charge transport layer can be formed without particular limitation and can be formed using a known method. For example, the charge transport layer can be formed by forming a coating film of a charge transport layer-forming coating liquid obtained by adding the above-mentioned components to a solvent, drying the coating film, and heating the coating film as needed.

[0178] Examples of solvents used to prepare the charge transport layer coating solution include common organic solvents such as aromatic hydrocarbons such as benzene, toluene, xylene, and chlorobenzene; ketones such as acetone and 2-butanol; halogenated aliphatic hydrocarbons such as dichloromethane, chloroform, and ethylene chloride; and cyclic or linear ethers such as tetrahydrofuran and ethyl ether. These solvents can be used alone or in combination of two or more.

[0179] Examples of the coating method for applying the charge transport layer-forming coating liquid onto the charge generating layer include common methods such as doctor blade coating, wire bar coating, spray coating, dip coating, bead coating, air knife coating, and curtain coating.

[0180] The thickness of the charge transport layer is preferably 5 μm or more and 30 μm or less, more preferably 8 μm or more and 20 μm or less, and further preferably 10 μm or more and 15 μm or less.

[0181] When the thickness of the charge transport layer is 30 μm or less, the charge generated in the charge generation layer by irradiation with neutralizing light is less likely to accumulate in the charge transport layer, resulting in less blurring of the image. From this perspective, the thickness of the charge transport layer is more preferably 20 μm or less, and even more preferably 15 μm or less.

[0182] A thickness of 5 μm or greater is preferred in terms of electrical properties of the photoreceptor. From this viewpoint, the thickness of the charge transport layer is more preferably 8 μm or greater, and even more preferably 10 μm or greater.

[0183] [Protective layer]

[0184] The protective layer is provided on the photosensitive layer. The protective layer is the outermost layer of the photoreceptor. For example, the protective layer is provided to suppress chemical changes in the photosensitive layer during charging or to improve the mechanical strength of the photosensitive layer.

[0185] The protective layer is preferably a cured film or a cross-linked film, and specifically, the following embodiment (1) or embodiment (2) is preferred. According to the following embodiment (1) or embodiment (2), chemical changes in the photosensitive layer during charging are suppressed, and the wear resistance of the protective layer is further improved.

[0186] Mode (1): A cured film or crosslinked film comprising a composition of a reactive charge transport material having a reactive group and a charge transport skeleton in the same molecule. That is, a layer comprising a polymer or crosslinked product of a reactive charge transport material. This layer may also comprise a polymer or crosslinked product of a reactive non-charge transport material having a reactive group in the molecule but no charge transport skeleton. This layer may also comprise a polymer or crosslinked product of a reactive charge transport material and a reactive non-charge transport material. This layer may also comprise a non-reactive charge transport material having no reactive group in the molecule.

[0187] Mode (2): A cured or crosslinked film comprising a composition of a non-reactive charge transport material having no reactive groups in its molecule and a reactive non-charge transport material having reactive groups in its molecule but no charge transport skeleton. Specifically, a layer comprising a polymer or crosslinked product of the non-reactive charge transport material and the reactive non-charge transport material.

[0188] The protective layer is preferably the embodiment (1) among the embodiments (1) and (2). The embodiment (1) has a higher hardness of the protective layer and is excellent in wear resistance compared to the embodiment (2).

[0189] The reactive charge transport material, the non-reactive charge transport material, and the reactive non-charge transport material may be selected from known materials. Preferred embodiments of the reactive charge transport material, the non-reactive charge transport material, and the reactive non-charge transport material will be described below.

[0190] Examples of the reactive group of the reactive charge transport material include a chain polymerizable group, an epoxy group, -OH, -OR [R represents an alkyl group], -NH2, -SH, -COOH, and -SiR a 3-n (OR b ) n [R a represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, R b represents a hydrogen atom, an alkyl group, or a trialkylsilyl group. n represents an integer of 1 to 3. ] and other well-known reactive groups. Examples of the reactive group in the reactive non-charge transport material include the reactive groups mentioned above.

[0191] As a chain polymerizable group, any functional group capable of free radical polymerization may be used, for example, a functional group having a carbon double bond. Specifically, a group having at least one selected from a vinyl group, a vinyl ether group, a vinyl thioether group, a styryl group (phenylvinyl group), a vinylphenyl group, an acryloyl group, a methacryloyl group, and derivatives thereof can be mentioned. As a chain polymerizable group, from the viewpoint of excellent reactivity, a group having at least one selected from a vinyl group, a styryl group (phenylvinyl group), a vinylphenyl group, an acryloyl group, a methacryloyl group, and derivatives thereof is preferred.

[0192] Examples of the charge transport skeleton of the reactive charge transport material include structures derived from the skeleton of a nitrogen-containing hole transport compound such as triarylamine compounds (compounds having a triarylamine skeleton), benzidine compounds (compounds having a benzidine skeleton), and hydrazone compounds (compounds having a hydrazone skeleton) and conjugated with nitrogen atoms. The charge transport skeleton of the reactive charge transport material is preferably a triarylamine skeleton.

[0193] The reactive charge transport material may be used alone or in combination of two or more.

[0194] As the reactive charge transport material, a compound represented by the following formula (A) is preferred from the viewpoint of excellent charge transport properties.

[0195]

[0196] In formula (A), Ar 1 、Ar 2 、Ar 3 and Ar 4 Each independently represents a substituted or unsubstituted aryl group, Ar 5 represents a substituted or unsubstituted aryl group or a substituted or unsubstituted arylene group, and D represents a chain polymerizable group, an epoxy group, -OH, -OR [R represents an alkyl group.], -NH2, -SH, -COOH or -SiRa 3-n (OR b ) n [R a represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted aryl group, R b represents a hydrogen atom, an alkyl group, or a trialkylsilyl group. n represents an integer of 1 to 3. ] wherein n1, n2, n3, n4, and n5 each independently represent an integer of 0 to 2, m represents 0 or 1, and the total number of D is 1 to 8.

[0197] From the viewpoint of obtaining a stronger protective layer, the total number of D is preferably 2 or more, more preferably 4 or more. From the viewpoint of reducing the proportion of unreacted reactive groups, the total number of D is preferably 7 or less, more preferably 6 or less.

[0198] In formula (A), Ar 1 、Ar 2 、Ar 3 and Ar 4 Each independently represents a substituted or unsubstituted aryl group. 1 、Ar 2 、Ar 3 and Ar 4 They can be the same or different from each other.

[0199] As the substituent in the substituted aryl group, as a substituent other than D, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a substituted or unsubstituted aryl group having 6 to 10 carbon atoms, etc. can be mentioned.

[0200] -Ar in formula (A) 1 -(D) n1 、-Ar 2 -(D) n2 、-Ar 3 -(D) n3 and -Ar 4 -(D) n4 Preferably, each independently represents any one of the following formulas (1) to (7).

[0201] In the following formulas (1) to (7), 1 、Ar 2 、Ar 3 and Ar 4 Separately connected -(D) n1 、-(D) n2 、-(D) n3 and-(D) n4 The summary is -(D) n .

[0202]

[0203] In formulae (1) to (7), D has the same meaning as "D" in formula (A), and n represents 1 or 2.

[0204] In formula (1), R 1 represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, or a phenyl group substituted with an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms.

[0205] In formula (2), R 2 and R 3 Each independently represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, a phenyl group substituted by an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, or a halogen atom.

[0206] In formula (3), R 4 represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, a phenyl group substituted by an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, and a represents an integer of 0 to 4.

[0207] In formula (7), two Ar's each independently represent a substituted or unsubstituted arylene group, Z represents a divalent organic linking group, and b represents 0 or 1.

[0208] Ar in formula (7) is preferably an arylene group represented by the following formula (8) or an arylene group represented by formula (9).

[0209]

[0210] In formula (8), R 5 represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, a phenyl group substituted by an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, and d represents an integer of 0 to 4.

[0211] In formula (9), R 6 and R 7Each independently represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, a phenyl group substituted by an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, and e and f each independently represent an integer of 0 to 4.

[0212] As Z in formula (7), it is preferably any one of a divalent linking group represented by the following formula (10), a divalent linking group represented by formula (11), a divalent linking group represented by formula (12), a divalent linking group represented by formula (13), a divalent linking group represented by formula (14), a divalent linking group represented by formula (15), a divalent linking group represented by formula (16), and a divalent linking group represented by formula (17), or a combination thereof.

[0213]

[0214] In formula (10), p represents an integer of 1 to 10.

[0215] In formula (11), q represents an integer of 1 to 10.

[0216] In formula (16), R 8 represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, a phenyl group substituted by an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, s represents an integer of 0 to 4, and W represents a divalent linking group.

[0217] In formula (17), R 9 represents an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, an unsubstituted phenyl group, a phenyl group substituted by an alkyl group having 1 to 4 carbon atoms or an alkoxy group having 1 to 4 carbon atoms, or a halogen atom, t represents an integer of 0 to 4, and W represents a divalent linking group.

[0218] As W in formula (16) and formula (17), it is preferably any one of a divalent linking group represented by the following formula (18), a divalent linking group represented by formula (19), a divalent linking group represented by formula (20), a divalent linking group represented by formula (21), a divalent linking group represented by formula (22), a divalent linking group represented by formula (23), a divalent linking group represented by formula (24), a divalent linking group represented by formula (25), and a divalent linking group represented by formula (26).

[0219]

[0220] In formula (25), u represents an integer greater than or equal to 0 and less than or equal to 3.

[0221] In formula (A), when m is 0, Ar 5 is a substituted or unsubstituted aryl group. 5 Related aryl groups include Ar 1 The above-mentioned aryl groups described in the preferred embodiment are as follows.

[0222] In formula (A), when m is 1, Ar 5 is a substituted or unsubstituted arylene group. 5 Related arylene groups include Ar 1 The above aryl group is preferably described by removing -N(Ar 3 -(D) n3 )(Ar 4 -(D) n4 ) substituted position of the hydrogen atom of the arylene group.

[0223] Examples of the reactive charge transport material include the following CTM(R1) to CTM(R4) and CTM(CP1) to CTM(CP4).

[0224]

[0225]

[0226]

[0227] The content of the reactive charge transport material is preferably 30% by mass or more and 100% by mass or less, more preferably 40% by mass or more and 100% by mass or less, and even more preferably 50% by mass or more and 100% by mass or less, relative to the solid content of the composition for forming the protective layer (e.g., a protective layer-forming coating liquid). When the content of the reactive charge transport material is within this range, the protective layer can be made thicker, thereby reducing the occurrence of charge leakage on the photoreceptor surface.

[0228] When a chain-polymerizable charge transport material is used as the reactive charge transport material, the content of the chain-polymerizable charge transport material is preferably 30% by mass or more and 100% by mass or less, more preferably 40% by mass or more and 100% by mass or less, and even more preferably 50% by mass or more and 100% by mass or less, relative to the solid content of the composition for forming the protective layer (e.g., a coating solution for forming a protective layer). When the content of the chain-polymerizable charge transport material is within the above range, the protective layer can be made thicker, thereby reducing the occurrence of charge leakage on the photoreceptor surface.

[0229] Examples of non-reactive charge transport materials include electron-transporting compounds such as p-benzoquinone, tetrachlorobenzoquinone, tetrabromobenzoquinone, and anthraquinone; tetracyanoquinolmethane compounds; fluorenone compounds such as 2,4,7-trinitrofluorenone; xanthone compounds; benzophenone compounds; cyanoethylene compounds; and vinyl compounds. Examples of non-reactive charge transport materials include hole-transporting compounds such as triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted vinyl compounds, stilbene compounds, anthracene compounds, and hydrazone compounds. These non-reactive charge transport materials may be used alone or in combination of two or more.

[0230] An example of the non-reactive charge transport material is the following CTM (NR1).

[0231]

[0232] Examples of the reactive non-charge transporting material include thermosetting resins, curing agents, etc. The reactive non-charge transporting material may be used alone or in combination of two or more.

[0233] Examples of the thermosetting resin include guanamine resin, melamine resin, phenol resin, urea resin, and alkyd resin.

[0234] Examples of the curing agent include compounds having a guanamine structure (hereinafter also referred to as “guanamine compounds”) and compounds having a melamine structure (hereinafter also referred to as “melamine compounds”).

[0235] Examples of embodiments of the protective layer include a cured film or crosslinked film comprising a polymer or crosslinked product of at least one selected from the group consisting of a reactive charge transport material, a guanoamine resin, a melamine resin, a guanoamine compound, and a melamine compound. A cured film or crosslinked film as the protective layer is preferred due to its superior wear resistance.

[0236] The protective layer may also contain fluororesin particles. A protective layer containing fluororesin particles forms irregularities on the outer peripheral surface of the protective layer, thereby further improving wear resistance.

[0237] Examples of the fluororesin constituting the fluororesin particles include polytetrafluoroethylene (PTFE, also known as tetrafluoroethylene resin), perfluoroalkoxy fluororesin, polychlorotrifluoroethylene, polychlorotrifluoroethylene, polydichlorodifluoroethylene, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymers, tetrafluoroethylene-hexafluoropropylene copolymers, tetrafluoroethylene-ethylene copolymers, tetrafluoroethylene-hexafluoropropylene-perfluoroalkyl vinyl ether copolymers, and tetrafluoroethylene-perfluoroalkoxyethylene copolymers. From the perspective of the wear resistance and cleanability of the protective layer, the fluororesin constituting the fluororesin particles is preferably polytetrafluoroethylene and a copolymer of tetrafluoroethylene and perfluoroalkoxyethylene. The fluororesin particles may be used alone or in combination of two or more.

[0238] The weight average molecular weight of the fluororesin constituting the fluororesin particles is preferably 3,000 to 5,000,000.

[0239] The average primary particle size of the fluororesin particles is preferably 0.05 μm or more and 10 μm or less, and more preferably 0.1 μm or more and 5 μm or less.

[0240] The average primary particle size of the fluororesin particles is a value obtained by measuring a dispersion in which the fluororesin particles are dispersed at a refractive index of 1.35 using a laser diffraction / scattering particle size distribution analyzer.

[0241] The mass ratio of the fluororesin particles in the protective layer is preferably 5 mass % or more and 15 mass % or less, more preferably 7 mass % or more and 12 mass % or less.

[0242] The protective layer is formed, for example, by preparing a protective layer-forming coating solution containing the aforementioned components and a solvent or dispersion medium, applying the protective layer-forming coating solution onto the photosensitive layer to form a coating film, drying the coating film, and optionally subjecting the coating film to a curing treatment such as heating.

[0243] Examples of solvents or dispersion media used to prepare the protective layer-forming coating solution include aromatic solvents such as toluene and xylene; ketone solvents such as methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester solvents such as ethyl acetate and butyl acetate; ether solvents such as tetrahydrofuran and dioxane; cellosolve solvents such as ethylene glycol monomethyl ether; and alcohol solvents such as isopropyl alcohol and butanol. These solvents may be used alone or in combination of two or more.

[0244] Examples of a method for applying the protective layer-forming coating liquid onto the photosensitive layer include common methods such as dip coating, top coating, wire bar coating, spray coating, blade coating, air knife coating, and curtain coating.

[0245] The thickness of the protective layer is preferably 2 μm or more and 10 μm or less, more preferably 3 μm or more and 9 μm or less, and even more preferably 4 μm or more and 8 μm or less.

[0246] When the thickness of the protective layer is 10 μm or less, the charge generated in the charge generating layer by irradiation with the neutralizing light is less likely to accumulate in the protective layer, resulting in less blurring of the image. From this viewpoint, the thickness of the protective layer is more preferably 9 μm or less, and even more preferably 8 μm or less.

[0247] When the thickness of the protective layer is 2 μm or more, charge leakage is less likely to occur on the surface of the photoreceptor. From this viewpoint, the thickness of the protective layer is more preferably 3 μm or more, and even more preferably 4 μm or more.

[0248] <Image forming apparatus, process cartridge>

[0249] The image forming apparatus of this embodiment includes: an electrophotographic photoreceptor; a charging device for charging the surface of the electrophotographic photoreceptor; an electrostatic latent image forming device for forming an electrostatic latent image on the surface of the charged electrophotographic photoreceptor; a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor using a developer containing toner to form a toner image; a transfer device for transferring the toner image to the surface of a recording medium; and a static eliminating device for irradiating the surface of the electrophotographic photoreceptor with static eliminating light after the toner image has been transferred to the surface of the recording medium. The electrophotographic photoreceptor of this embodiment is employed as the electrophotographic photoreceptor.

[0250] The image forming apparatus of this embodiment includes a static eliminator. Image forming apparatuses equipped with static eliminators tend to produce blurring during continuous image formation. By employing the electrophotographic photoreceptor of this embodiment in an image forming apparatus equipped with a static eliminator, blurring during continuous image formation can be suppressed.

[0251] The charging device included in the image forming apparatus of this embodiment may be a charging device in which the charging member contacts the surface of the electrophotographic photoreceptor (contact type) or a charging device in which the charging member does not contact the surface of the electrophotographic photoreceptor (non-contact type).

[0252] The charging device provided in the image forming apparatus of this embodiment may be any one of a charging device that applies only a DC voltage to a charging component (DC charging method), a charging device that applies only an AC voltage to a charging component (AC charging method), and a charging device that applies a voltage superimposed on an AC voltage to a charging component (AC / DC charging method).

[0253] Image forming apparatuses equipped with contact and DC charging devices tend to produce blurring during continuous image formation. By employing the electrophotographic photoreceptor of this embodiment in an image forming apparatus equipped with contact and DC charging devices, blurring during continuous image formation can be suppressed.

[0254] The image forming device of this embodiment applies the following well-known image forming devices: a device equipped with a fixing device for fixing the colorant image transferred to the surface of a recording medium; a device using a direct transfer method for transferring the colorant image formed on the surface of an electronic photographic photosensitive body to a direct recording medium; a device using an intermediate transfer method for transferring the colorant image formed on the surface of an electronic photographic photosensitive body to the surface of an intermediate transfer body for the first time, and for transferring the colorant image transferred to the surface of the intermediate transfer body to the surface of a recording medium for the second time; a device equipped with a cleaning device for cleaning the surface of an electronic photographic photosensitive body before charging after the transfer of the colorant image; a device equipped with an electronic photographic photosensitive body heating component for increasing the temperature of the electronic photographic photosensitive body and reducing the relative temperature, etc.

[0255] In the case of an intermediate transfer method device, the transfer device, for example, has the following structure: an intermediate transfer body for transferring a colorant image on a surface, a primary transfer device for transferring the colorant image formed on the surface of the electronic photographic photosensitive body to the surface of the intermediate transfer body for the first time, and a secondary transfer device for secondary transferring the colorant image transferred to the surface of the intermediate transfer body to the surface of the recording medium.

[0256] The image forming apparatus of the present embodiment may be any of a dry development system image forming apparatus and a wet development system (development system using a liquid developer) image forming apparatus.

[0257] In the image forming apparatus of this embodiment, for example, the portion comprising the electrophotographic photoreceptor may be a toner cartridge structure (process cartridge) that is attachable to and detachable from the image forming apparatus. As the process cartridge, for example, a process cartridge comprising the electrophotographic photoreceptor of this embodiment is preferably used. In addition to the electrophotographic photoreceptor, the process cartridge may also comprise, for example, at least one selected from the group consisting of a charging device, an electrostatic latent image forming device, a developing device, and a transfer device.

[0258] An example of the image forming apparatus according to the present embodiment is shown below, but the present invention is not limited thereto. The main parts shown in the drawings will be described, and description of the other parts will be omitted.

[0259] Figure 2 This is a schematic configuration diagram showing an example of the image forming apparatus according to the present embodiment.

[0260] like Figure 2As shown, the image forming apparatus 100 of this embodiment includes a process cartridge 300 including an electrophotographic photoreceptor 7, an exposure device 9 (an example of an electrostatic latent image forming device), a transfer device 40 (a primary transfer device), and an intermediate transfer member 50. In the image forming apparatus 100, the exposure device 9 is positioned so as to expose the electrophotographic photoreceptor 7 through the opening of the process cartridge 300. The transfer device 40 is positioned so as to face the electrophotographic photoreceptor 7 across the intermediate transfer member 50, with a portion of the intermediate transfer member 50 in contact with the electrophotographic photoreceptor 7. Although not shown, the image forming apparatus 100 further includes a secondary transfer device that transfers the toner image transferred to the intermediate transfer member 50 onto a recording medium (e.g., paper). The intermediate transfer member 50, the transfer device 40 (a primary transfer device), and the secondary transfer device (not shown) constitute an example of a transfer device.

[0261] Figure 2 The process cartridge 300 in the embodiment of the present invention integrally supports the electrophotographic photoreceptor 7, the charging device 8 (an example of a charging device), the developing device 11 (an example of a developing device), and the cleaning device 13 (an example of a cleaning device) within a housing. The cleaning device 13 includes a cleaning blade (an example of a cleaning member) 131, which is arranged to contact the surface of the electrophotographic photoreceptor 7. The cleaning member may be a conductive or insulating fibrous member instead of the cleaning blade 131, and may be used alone or in combination with the cleaning blade 131.

[0262] exist Figure 2 2 shows an example in which a fibrous member 132 (roller-shaped) for supplying the lubricant 14 to the surface of the electrophotographic photoreceptor 7 is provided as the cleaning device, but the fibrous member 132 may be arranged as needed.

[0263] Next, each component of the image forming apparatus according to this embodiment will be described.

[0264] - Charging device -

[0265] As the charging device 8, for example, a contact charger using a conductive or semiconductive charging roller, a charging brush, a charging film, a charging rubber blade, a charging tube, etc. can be used. Alternatively, a non-contact roller charger, a scorotron charger using corona discharge, a corotron charger, or other known chargers can be used.

[0266] The charging device 8 may be either a contact-based charging device or a non-contact-based charging device. The charging device 8 may also be any of a DC-based charging device, an AC-based charging device, and an AC / DC-based charging device. Examples of embodiments of the charging device 8 include a contact-based and DC-based charging device.

[0267] -Exposure device-

[0268] As the exposure device 9, for example, there can be cited an optical system device that exposes light such as semiconductor laser, LED light, liquid crystal shutter light to the surface of the electrophotographic photoreceptor 7 in a determined image shape. The wavelength of the light source is set within the spectral sensitivity area of ​​the electrophotographic photoreceptor. As the wavelength of the semiconductor laser, near-infrared having an oscillation wavelength around 780nm is the mainstream. However, it is not limited to this wavelength, and a 600nm-class oscillation wavelength laser or a laser having an oscillation wavelength of more than 400nm and less than 450nm can also be used as a blue laser. In addition, a surface-emitting laser source that can output multiple beams in order to form a color image is also effective.

[0269] -Developing device-

[0270] Examples of the developing device 11 include general developing devices that develop the electrophotographic photoreceptor 7 with or without contacting the developer. The developing device 11 is not particularly limited as long as it has the functions described above, and can be selected based on the intended purpose. Examples include known developing devices that utilize a brush, roller, or the like to deposit a single-component developer or a two-component developer onto the electrophotographic photoreceptor 7. Among these, a developing roller that retains the developer on its surface is preferably used.

[0271] The developer used in the developing device 11 may be a single-component developer containing only toner or a two-component developer containing toner and a carrier. Furthermore, the developer may be magnetic or non-magnetic. These developers are known developers.

[0272] - Cleaning device -

[0273] The cleaning device 13 uses a cleaning blade type including a cleaning blade 131. In addition to the cleaning blade type, a brush cleaning method or a simultaneous development cleaning method may be used.

[0274] -Static elimination device-

[0275] The static elimination device 15 irradiates the surface of the electrophotographic photoreceptor 7 with static elimination light to eliminate the residual potential on the electrophotographic photoreceptor 7. The static elimination device 15 is a light irradiation device that irradiates the entire area of ​​the electrophotographic photoreceptor 7 in the direction of the rotation axis. Examples thereof include a halogen lamp, a tungsten lamp, and an LED lamp. The wavelength of the static elimination light is, for example, 600 nm to 700 nm, and the amount of the static elimination light is, for example, 5 mJ / m 2 Above and 100mJ / m 2 the following.

[0276] The electrophotographic photoreceptor 7 having the toner image transferred to the intermediate transfer member 50 has residual toner and other adhering substances on its surface removed by the cleaning device 13 , and is then irradiated with neutralizing light by the neutralizing device 15 to remove any remaining charges on its surface.

[0277] Figure 2 Although the embodiment in which the static eliminating device 15 is arranged downstream of the cleaning device 13 is shown, the static eliminating device 15 may be arranged upstream of the cleaning device 13 .

[0278] - Transfer device -

[0279] Examples of the transfer device 40 include a contact transfer charger using a belt, roller, film, or rubber blade, a scorotron transfer charger using corona discharge, and other known transfer chargers.

[0280] -Intermediate transfer body-

[0281] As the intermediate transfer member 50, a belt-shaped intermediate transfer member (intermediate transfer belt) made of polyimide, polyamideimide, polycarbonate, polyarylate, polyester, rubber, etc. imparted with semiconductivity is used. In addition, as the form of the intermediate transfer member, a drum-shaped intermediate transfer member can also be used in addition to the belt-shaped intermediate transfer member.

[0282] Figure 3 This is a schematic structural diagram showing another example of the image forming apparatus according to the present embodiment.

[0283] Figure 3 The illustrated image forming apparatus 120 is a tandem-type multi-color image forming apparatus equipped with four process cartridges 300. In image forming apparatus 120, four process cartridges 300 are arranged side by side on an intermediate transfer body 50, with one electrophotographic photoreceptor used for each color. Aside from its tandem configuration, image forming apparatus 120 has the same structure as image forming apparatus 100.

[0284] [Example]

[0285] Hereinafter, embodiments of the present invention will be described in detail with reference to examples, but the embodiments of the present invention are not limited to these examples.

[0286] In the following description, "parts" and "%" are based on mass unless otherwise specified.

[0287] In the following description, unless otherwise specified, synthesis, production, handling, measurement, etc. were performed at room temperature (25°C ± 3°C).

[0288] <Photoreceptor Manufacturing>

[0289] [Example 1]

[0290] - Formation of the base coat -

[0291] As a conductive substrate, an aluminum cylindrical tube having an outer diameter of 30 mm, a length of 365 mm, and a wall thickness of 1 mm was prepared.

[0292] 100 parts of zinc oxide (average particle size 70 nm, specific surface area 15 m 2 / g, manufactured by Tayca) and 500 parts of toluene were stirred and mixed, and 1.3 parts of a silane coupling agent (N-2-(aminoethyl)-3-aminopropyltrimethoxysilane, trade name: KBM603, Shin-Etsu Chemical Co., Ltd.) was added and stirred for 2 hours. Subsequently, the toluene was distilled off under reduced pressure, and the mixture was calcined at 120°C for 3 hours to obtain zinc oxide surface-treated with the silane coupling agent.

[0293] 110 parts of surface-treated zinc oxide and 500 parts of tetrahydrofuran were stirred and mixed, and a solution of 0.6 parts of alizarin dissolved in 50 parts of tetrahydrofuran was added, followed by stirring at 50°C for 5 hours. The solid content was then filtered and separated by vacuum filtration and dried at 60°C under reduced pressure to obtain zinc oxide with alizarin added thereto.

[0294] 60 parts of alizarin-imparted zinc oxide, 13.5 parts of a curing agent (blocked isocyanate, trade name: Sumidur 3175, Sumitomo Bayer Urethanes Co., Ltd.), and 15 parts of a butyral resin (trade name: S-LEC BM-1, Sekisui Chemical Co., Ltd.) were dissolved in 100 parts of a solution of 68 parts of methyl ethyl ketone and mixed with 5 parts of methyl ethyl ketone. The mixture was dispersed for 2 hours using a sand mill with 1 mm diameter glass beads to obtain a dispersion. 0.005 parts of dioctyltin dilaurate and 4 parts of silicone resin particles (trade name: TOSPEARL 145, Momentive Performance Materials Japan Contract Co., Ltd.) were added to the dispersion as catalysts to obtain a coating solution for forming a primer layer. The coating solution for forming a primer layer was applied to the outer peripheral surface of the conductive substrate by dip coating and dried and cured at 170°C for 40 minutes to form a primer layer with an average thickness of 25 μm.

[0295] -Formation of the Charge Generation Layer-

[0296] A mixture consisting of 15 parts of hydroxygallium phthalocyanine (having diffraction peaks at Bragg angles (2θ±0.2°) of at least 7.5°, 9.9°, 12.5°, 16.3°, 18.6°, 25.1°, and 28.3° in an X-ray diffraction spectrum using CuKα characteristic X-rays) as a charge generating material, 10 parts of a vinyl chloride-vinyl acetate copolymer resin (trade name: VMCH, Unicar Co., Ltd., Japan) as a binder resin, and 200 parts of n-butyl acetate was dispersed in a sand mill using 1 mm diameter glass beads for 4 hours. 175 parts of n-butyl acetate and 180 parts of methyl ethyl ketone were added to the dispersion and stirred to obtain a coating solution for forming a charge generating layer. The coating solution for forming a charge generating layer was dip-coated onto the undercoat layer and dried at room temperature (25°C±3°C) to form a charge generating layer with an average thickness of 0.18 μm.

[0297] -Formation of Charge Transport Layer-

[0298] Adhesive resin: 50 parts polycarbonate resin (PC1) (viscosity average molecular weight 50,000)

[0299] Charge transport material: CTM (1) 50 parts

[0300] Solvent: 200 parts of tetrahydrofuran

[0301] Solvent: 50 parts toluene

[0302] The above materials were mixed to obtain a charge transport layer coating solution, which was dip-coated on the charge generating layer and dried at 145° C. for 30 minutes to form a charge transport layer having a thickness of 11.0 μm.

[0303] The chemical structures of the polycarbonate resin (PC1) and CTM (1) are shown below. The numerical values ​​in the structural formula of the polycarbonate resin (PC1) are molar ratios.

[0304] Polycarbonate resin (PC1)

[0305]

[0306] -Formation of protective layer-

[0307] Reactive charge transport material: CTM (R1) 70 parts

[0308] Reactive charge transport material: CTM (R2) 15 parts

[0309] Reactive non-charge transport material (thermosetting resin): 4.4 parts of benzoguanamine resin (trade name: Nikalac BL-60, Sanwa Chemical Co., Ltd.)

[0310] Curing catalyst: NACURE 5225 (King Industries) 0.1 part

[0311] Solvent: 220 parts of 2-propanol

[0312] The above materials were mixed to obtain a coating solution for forming a protective layer. This coating solution was dip-coated onto the charge transport layer and dried at room temperature (25°C ± 3°C) for 30 minutes. The protective layer was then cured by heating in a heating furnace at 155°C under a nitrogen flow at an oxygen concentration of 110 ppm for 20 minutes to form a protective layer with a thickness of 7.0 μm.

[0313] The chemical structures of CTM(R1) and CTM(R2) are shown below.

[0314]

[0315] [Examples 2 to 7, Comparative Examples 1 and 2]

[0316] A photoreceptor was produced in the same manner as in Example 1 except that the thickness of the charge transport layer and the thickness of the protective layer were changed as shown in Table 1.

[0317] [Example 11]

[0318] A photoreceptor was produced in the same manner as in Example 1 except that the formation of the charge transport layer and the formation of the protective layer were changed as follows.

[0319] -Formation of Charge Transport Layer-

[0320] Adhesive resin: 50 parts of polyarylate resin (PA1) (weight average molecular weight 80,000)

[0321] Charge transport material: CTM (2) 50 parts

[0322] Solvent: 200 parts of tetrahydrofuran

[0323] Solvent: 50 parts toluene

[0324] The above materials were mixed to form a charge transport layer coating solution, which was dip-coated on the charge generating layer and dried at 145° C. for 30 minutes to form a charge transport layer having a thickness of 11.0 μm.

[0325] The chemical structures of the polyarylate resin (PA1) and CTM (2) are shown below. The numerical values ​​in the structural formula of the polyarylate resin (PA1) are molar ratios.

[0326] Polyarylate resin (PA1)

[0327]

[0328]

[0329] -Formation of protective layer-

[0330] Reactive charge transport material: CTM (R1) 70 parts

[0331] Reactive charge transport material: CTM (R2) 15 parts

[0332] Reactive non-charge transport material (thermosetting resin): 4.4 parts of benzoguanamine resin (trade name: Nikalac BL-60, Sanwa Chemical Co., Ltd.)

[0333] Curing catalyst: NACURE 5225 (King Industries) 0.1 part

[0334] Solvent: 220 parts of 2-propanol

[0335] The above materials were mixed to obtain a coating solution for forming a protective layer. This coating solution was dip-coated onto the charge transport layer and dried at room temperature (25°C ± 3°C) for 30 minutes. The protective layer was then cured by heating in a heating furnace at 155°C under a nitrogen flow at an oxygen concentration of 110 ppm for 20 minutes to form a protective layer with a thickness of 7.0 μm.

[0336] [Examples 12 to 17, Comparative Examples 11 and 12]

[0337] A photoreceptor was produced in the same manner as in Example 11 except that the thickness of the charge transport layer and the thickness of the protective layer were changed as shown in Table 1.

[0338] Performance Evaluation

[0339] As an image forming apparatus equipped with a charging device using a contact-type DC charging method and a static elimination device using light for static elimination, a DocuCentre-V C2263 (Fujifilm Business Innovation Co., Ltd.) was prepared. The static elimination device had an LED light source, a static elimination light wavelength of 600 nm to 700 nm, and a static elimination light intensity of 50 mJ / m 2 The photoreceptor of each example or each comparative example was set in an image forming apparatus.

[0340] [Decrease in surface potential]

[0341] The following operations were continuously performed in an environment with a temperature of 28° C. and a relative humidity of 85%.

[0342] A potential probe of a surface potentiometer (Trek Japan Co., Ltd., Model 347) was set at the developer position of the above-mentioned image forming apparatus. Five sheets of A4-sized plain paper were fed, and the initial surface potential (V) was measured. The potential probe was removed, and 1,000 sheets of A4-sized plain paper were fed. The potential probe was set again at the developer position, and five sheets of A4-sized plain paper were fed, and the surface potential (V) after continuous feeding was measured. The surface potential (V) after continuous feeding was subtracted from the initial surface potential (V), and the decrease in surface potential (V) was calculated. The results are shown in Table 1. The decrease in surface potential was less than 25V, which was within the allowable range.

[0343] [Vague]

[0344] The image forming apparatus was used to output 1000 sheets of A4-sized plain paper with solid black images at a temperature of 22° C. and a relative humidity of 55%. Five A4-sized plain papers were then fed, visually inspected, and classified as follows.

[0345] A: No blur.

[0346] B: Blurring occurs, but is within the acceptable range.

[0347] C: Significant blurring occurs. Outside the permissible range.

[0348] [Charge Leak]

[0349] The following operations were performed continuously under an environment of a temperature of 22° C. and a relative humidity of 55%.

[0350] A voltage of 2 kV was applied to the charging roller of the above-mentioned image forming apparatus. After 30 minutes, discharge was applied to one point on the surface of the photoreceptor to check whether a black spot due to a pinhole was generated.

[0351] A: No black spots (leakage).

[0352] B: Slight black spots (leakage) were generated, but within the allowable range.

[0353] C: Obvious black spots (leakage) occurred. Outside the allowable range.

[0354] [Table 1]

[0355]

[0356] (Note) (((1)))

[0358] An electrophotographic photoreceptor, comprising:

[0359] Conductive substrate;

[0360] a charge generating layer, the charge generating layer being disposed on the conductive substrate;

[0361] a charge transport layer disposed on the charge generation layer; and

[0362] a protective layer, the protective layer being arranged on the charge transport layer,

[0363] The ratio L / ε of the total thickness L (μm) of the charge transport layer and the protective layer to the dielectric constant ε (F / m) of the charge transport layer and the protective layer in the thickness direction is 3 or more and 6 or less. (((2)))

[0365] The electrophotographic photoreceptor according to (((1))), wherein

[0366] The value of the ratio L / ε is 4.5 or more and 5.5 or less. (((3)))

[0368] The electrophotographic photoreceptor according to (((1))) or (((2))), wherein

[0369] The protective layer is a hardened film or a cross-linked film of a composition containing a reactive charge transporting material. (((4)))

[0371] The electrophotographic photoreceptor according to any one of (((1))) to (((3))), wherein

[0372] The total thickness L is greater than or equal to 10 μm and less than or equal to 20 μm. (((5)))

[0374] The electrophotographic photoreceptor according to any one of (((1))) to (((4))), wherein

[0375] The value of the ratio L2 / L1 of the thickness L2 of the protective layer to the thickness L1 of the charge transport layer is 0.1 or more and 1 or less. (((6)))

[0377] The electrophotographic photoreceptor according to any one of (((1))) to (((5))), wherein

[0378] The electrophotographic photoreceptor is used in an image forming apparatus, wherein the image forming apparatus comprises:

[0379] a charging device that charges the surface of the electrophotographic photoreceptor and includes a charging member in contact with the electrophotographic photoreceptor, and applies only a DC voltage to the charging member; and

[0380] A static eliminating device that removes static electricity by irradiating a surface of an electrophotographic photoreceptor with static eliminating light after transferring a toner image to a surface of a recording medium. (((7)))

[0382] A processing box, wherein

[0383] An electrophotographic photoreceptor according to any one of (((1))) to (((5))),

[0384] The process cartridge is attachable to and detachable from the image forming apparatus. (((8)))

[0386] The process cartridge according to (((7))), wherein

[0387] The device further includes a static eliminating device for eliminating static by irradiating the surface of the electrophotographic photoreceptor with static eliminating light after the toner image is transferred to the surface of the recording medium. (((9)))

[0389] The process cartridge according to (((7))) or (((8))), wherein

[0390] The device further includes a charging device for charging the surface of the electrophotographic photoreceptor and having a charging member in contact with the electrophotographic photoreceptor, wherein the charging device applies only a DC voltage to the charging member. (((10)))

[0392] An image forming apparatus comprising:

[0393] The electrophotographic photoreceptor according to any one of (((1))) to (((5)));

[0394] a charging device for charging the surface of the electrophotographic photoreceptor;

[0395] an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor;

[0396] a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image;

[0397] a transfer device that transfers the toner image to a surface of a recording medium; and

[0398] A static eliminating device is provided for irradiating the surface of the electrophotographic photoreceptor with static eliminating light to eliminate static after the toner image is transferred to the surface of the recording medium. (((11)))

[0400] The image forming apparatus according to (((10))), wherein

[0401] The charging device includes a charging member in contact with the electrophotographic photoreceptor, and applies only a DC voltage to the charging member.

[0402] According to (((1))), (((3))) or (((6))), an electronic photographic photoreceptor is provided that is less likely to produce charging leakage than an electronic photographic photoreceptor having a ratio L / ε value of less than 3, and an electronic photographic photoreceptor is provided that is less likely to produce blur when continuously forming images than an electronic photographic photoreceptor having a ratio L / ε value exceeding 6.

[0403] According to (((2))), an electronic photographic photoreceptor is provided that is less likely to cause charging leakage than an electronic photographic photoreceptor having a ratio L / ε value of less than 4.5, and an electronic photographic photoreceptor is provided that is less likely to cause blurring when continuously forming images than an electronic photographic photoreceptor having a ratio L / ε value exceeding 5.5.

[0404] According to (((4))), an electronic photographic photoreceptor is provided, which is less likely to cause charge leakage than an electronic photographic photoreceptor in which the total thickness L of the charge transport layer and the protective layer is less than 10 μm, and an electronic photographic photoreceptor is provided, which is less likely to cause blurred electronic photographic photoreceptor when continuously forming images than an electronic photographic photoreceptor in which the total thickness L of the charge transport layer and the protective layer exceeds 20 μm.

[0405] According to (((5))), an electrophotographic photoreceptor is provided that is less likely to cause charge leakage than an electrophotographic photoreceptor having a ratio L2 / L1 of the thickness L2 of the protective layer to the thickness L1 of the charge transport layer of less than 0.1.

[0406] According to (((7))), (((8))) or (((9))), a processing box is provided that is less likely to produce charging leakage than a processing box in which the value of the ratio L / ε of the electronic photographic photosensitive body is less than 3, and a processing box is provided that is less likely to produce blur when continuously forming images than a processing box in which the value of the ratio L / ε of the electronic photographic photosensitive body exceeds 6.

[0407] According to (((10))) or (((11))), an image forming device is provided that is less likely to produce charging leakage than an image forming device in which the value of the ratio L / ε of the electronic photographic photoreceptor is less than 3, and an image forming device is provided that is less likely to produce blur when continuously forming images than an image forming device in which the value of the ratio L / ε of the electronic photographic photoreceptor is greater than 6.

Claims

1. An electrophotographic photoreceptor, characterized in that have: Conductive substrate; a charge generating layer, the charge generating layer being disposed on the conductive substrate; a charge transport layer, the charge transport layer being disposed on the charge generating layer; as well as a protective layer, the protective layer being arranged on the charge transport layer, The ratio L / ε of the total thickness L (μm) of the charge transport layer and the protective layer to the dielectric constant ε (F / m) of the charge transport layer and the protective layer in the thickness direction is 3 or more and 6 or less.

2. The electrophotographic photoreceptor according to claim 1, wherein The value of the ratio L / ε is 4.5 or more and 5.5 or less.

3. The electrophotographic photoreceptor according to claim 1 or 2, wherein The protective layer is a hardened film or a cross-linked film of a composition containing a reactive charge transport material.

4. The electrophotographic photoreceptor according to any one of claims 1 to 3, wherein The total thickness L is greater than or equal to 10 μm and less than or equal to 20 μm.

5. The electrophotographic photoreceptor according to any one of claims 1 to 4, wherein The value of the ratio L2 / L1 of the thickness L2 of the protective layer to the thickness L1 of the charge transport layer is 0.1 or more and 1 or less.

6. The electrophotographic photoreceptor according to any one of claims 1 to 5, wherein The electrophotographic photoreceptor is used in an image forming apparatus, wherein the image forming apparatus comprises: a charging device for charging the surface of the electrophotographic photoreceptor and comprising a charging member in contact with the electrophotographic photoreceptor, wherein only a DC voltage is applied to the charging member; as well as A static eliminating device that removes static electricity by irradiating a surface of an electrophotographic photoreceptor with static eliminating light after transferring a toner image to a surface of a recording medium.

7. A processing cartridge, characterized in that: An electrophotographic photoreceptor according to any one of claims 1 to 5, The process cartridge is attachable to and detachable from the image forming apparatus.

8. The process cartridge according to claim 7, wherein The device further includes a static eliminating device for eliminating static by irradiating the surface of the electrophotographic photoreceptor with static eliminating light after the toner image is transferred to the surface of the recording medium.

9. The process cartridge according to claim 7 or 8, wherein A charging device is further provided, the charging device charges the surface of the electrophotographic photoreceptor and has a charging member in contact with the electrophotographic photoreceptor. The charging device applies only a DC voltage to the charging member.

10. An image forming apparatus, characterized in that: have: The electrophotographic photoreceptor according to any one of claims 1 to 5; a charging device for charging the surface of the electrophotographic photoreceptor; an electrostatic latent image forming device for forming an electrostatic latent image on the charged surface of the electrophotographic photoreceptor; a developing device for developing the electrostatic latent image formed on the surface of the electrophotographic photoreceptor with a developer containing toner to form a toner image; a transfer device for transferring the toner image to a surface of a recording medium; as well as A static eliminating device is provided for irradiating the surface of the electrophotographic photoreceptor with static eliminating light to eliminate static after the toner image is transferred to the surface of the recording medium.

11. The image forming apparatus according to claim 10, wherein The charging device includes a charging member in contact with the electrophotographic photoreceptor, and applies only a DC voltage to the charging member.

Images