electrophotographic device

Abstract

To provide an electrophotographic device that can control the potential of an exposure part of a photoreceptor with high accuracy in a short time.SOLUTION: An electrophotographic device has: an electrophotographic photoreceptor; electrifying means; image exposure means; developing means; transfer means; charge transfer amount detection means that detects the amount of charge transfer per unit time due to discharge to the electrophotographic photoreceptor; and exposure part potential control means that causes the electrifying means to electrify the electrophotographic photoreceptor, causes the image exposure means to perform image exposure with a light intensity at at least one point at a position having a weaker light intensity than the light intensity indicating the minimum value of a normalized radius of curvature R indicated by the following formula (E1) of the electrophotographic photoreceptor obtained by the EV curve measurement method, and with light intensities at at least two points at a position having a more intense light intensity than that indicating the minimum value of the normalized radius of curvature, causes the charge transfer amount detection means to detect the amount of charge transfer per unit time to the electrophotographic photoreceptor when the exposure part is electrified, and controls the potential of the exposure part of the electrophotographic photoreceptor from a result of detection.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present invention relates to an electrophotographic apparatus. [Background technology]

[0002] In recent years, there has been a demand for electrophotographic apparatuses that produce higher image quality, and there is a demand for apparatuses that output image quality that is highly stable despite external environments such as temperature and humidity, as well as during repeated use. In electrophotographic devices using electrophotographic photoreceptors (also called photoconductors), such as copiers, laser beam printers, and facsimiles, the photoreceptor is first uniformly charged, and an electrostatic latent image is formed on the photoreceptor using an image exposure means such as a laser scanner. The electrostatic latent image is then developed with toner to form a toner image on the photoreceptor. The toner image is transferred from the photoreceptor to a transfer material such as paper, and the transferred toner image is fixed using heat, pressure, etc., thereby forming an image.

[0003] Incidentally, when charging is performed by a charging means, for example, a charging roller, it is known that the voltage at which a high voltage is applied to the charging roller and discharge begins between the charging roller and the photosensitive member changes depending on the environment (temperature and humidity) in which the electrophotographic apparatus is placed, repeated use of the apparatus, the film thickness of the photosensitive member, etc. It is also known that the photosensitivity of the photosensitive member changes depending on the environment, repeated use, film thickness, etc., and that even when a constant amount of light is irradiated by the image exposure means, the surface potential of the photosensitive member changes. For this reason, even if the development potential is constant, the surface potential of the photosensitive member, particularly the potential of the exposed portion after image exposure, changes, resulting in a problem that the target image density cannot be obtained.

[0004] As a method for suppressing deviation from the target density due to changes in the surface potential of the photosensitive member caused by the various factors described above (maintaining constant image quality), Patent Document 1 proposes a method of directly measuring the surface potential of the photosensitive member using a surface electrometer and controlling the density based on the measured value. However, the surface potential measurement method of Patent Document 1 has problems such as the need to secure space for the electrometer within the device and the cost involved.

[0005] Also, as in Patent Document 2, a method for measuring surface potential without using an electrometer has been proposed, which utilizes a transfer roller in contact with the photosensitive member. This method involves applying a voltage to the surface of the photosensitive member using the transfer roller, charging the photosensitive member, measuring the current flowing through the photosensitive member, and then correcting the applied voltage and the measured current to determine the surface potential. However, in order to perform the correction, it is necessary to understand the amount of change in the potential characteristics of the photosensitive member due to various fluctuation factors, and during the correction process, a step must be taken to control the measured value to a corrected output value. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Publication No. 5-66638 [Patent Document 2] Patent No. 6478721 Summary of the Invention [Problem to be solved by the invention]

[0007] As mentioned above, if an electrometer is used to maintain a constant surface potential in order to stably maintain the image quality of the output image, the electrophotographic apparatus becomes larger in size and costs increase. Furthermore, in the case of surface potential control without using the electrometer, it is necessary to follow a procedure to obtain a corrected value from an actually measured current value, which poses problems such as increased costs and reduced accuracy due to the complex process.

[0008] The object of the present invention is to provide an electrophotographic device that can control the potential of the exposed portion of the photosensitive member with high precision in a short time while reducing the size and cost of the electrophotographic device by detecting the amount of current (amount of charge transfer per unit time) flowing in the exposed portion of the electrophotographic photosensitive member and performing simple surface potential control that is only possible in combination with the electrical characteristics of a specific photosensitive member. [Means for solving the problem]

[0009] The above object can be achieved by the present invention as follows. That is, the electrophotographic apparatus according to the present invention comprises an electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member, image exposure means for irradiating the surface of the electrophotographic photosensitive member with image exposure light to form an electrostatic latent image on the surface of the electrophotographic photosensitive member, developing means for developing the electrostatic latent image with toner to form a toner image on the surface of the electrophotographic photosensitive member, transfer means for transferring the toner image from the surface of the electrophotographic photosensitive member to a transfer material, charge transfer amount detection means for detecting the amount of charge transfer per unit time due to discharge to the electrophotographic photosensitive member, and the charging means. an electrophotographic apparatus comprising: a step for charging the electrophotographic photosensitive member; an imagewise exposure means for imagewise exposing the electrophotographic photosensitive member with at least one light amount weaker than the light amount showing the minimum value of a normalized radius of curvature R of the electrophotographic photosensitive member, which is expressed by the following formula (E1), and at least two light amounts stronger than the light amount showing the minimum value of the normalized radius of curvature R; a charge transfer amount detection means for detecting an amount of charge transferred per unit time to the electrophotographic photosensitive member when the exposed portion is charged; and an exposed portion potential control means for controlling a potential of the exposed portion of the electrophotographic photosensitive member based on the detection result; The electrophotographic photoreceptor is At a temperature of 23.5°C and a relative humidity of 50%RH, (1) setting the surface potential of the electrophotographic photosensitive member to 0 [V]; (2) charging the electrophotographic photosensitive member for 0.005 seconds so that the absolute value of the initial surface potential of the electrophotographic photosensitive member becomes 500 [V]; (3) 0.02 seconds after the start of charging, the wavelength is 805 [nm] and the intensity is 25 [mW / cm 2 ] light for t seconds continuously. exp [μJ / cm 2 ] light, (4) 0.06 seconds after the start of charging, the absolute value of the surface potential of the electrophotographic photosensitive member after exposure, measured, is V exp When [V] is used, Measurements (1) to (4) are performed by changing t. exp to 0.000 [μJ / cm 2 ] to 1.000 [μJ / cm 2 ] up to 0.001 [μJ / cm 2] and repeat the process. The horizontal axis is I exp The vertical axis is V exp In a graph where V of the graph exp = 250[V], the amount of light when 1 / 2 [μJ / cm 2 ], 10·I 1 / 2 The horizontal axis I exp The normalized light intensity is x, and the value 500 [V] on the vertical axis of the graph (x=0) is 1, and the value when x=1 is 0. exp When the normalized surface potential is y, In a graph with the horizontal axis being x and the vertical axis being y, the minimum value of the normalized radius of curvature R calculated by the following formula (E1) is 0.24 or less.

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[0010] According to the present invention, by detecting the amount of current (amount of charge transfer per unit time) flowing through the exposed portion of the electrophotographic photosensitive member and performing simple surface potential control that is only possible in combination with the electrical characteristics of a specific photosensitive member, it is possible to provide an electrophotographic device that can control the potential of the exposed portion of the photosensitive member with high precision in a short time while reducing the size and cost of the electrophotographic device. [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a diagram showing an example of a layer structure of an electrophotographic photosensitive member according to the present invention. [Figure 2] 1 is a diagram showing an example of a schematic configuration of an electrophotographic apparatus provided with a process cartridge having an electrophotographic photosensitive member according to the present invention. [Figure 3] 1 shows a latent image formation pattern when detected by a charge transfer amount detection means. [Figure 4] 4 shows the image exposure amount and charge transfer amount when the latent image pattern shown in FIG. 3 is formed in the electrophotographic photosensitive member according to Example 1. [Figure 5] 1 is a graph showing the relationship between the charge transfer amount and the light amount in the electrophotographic photosensitive member according to Example 1, and shows the light amount (★) at the minimum value of the normalized radius of curvature R. [Figure 6] Figure 4 shows the amount of light (★) at the minimum value of the normalized radius of curvature R based on the transition of the surface potential when the image exposure amount of the photosensitive member used is changed. [Figure 7] 1 is a graph obtained in Example 1, with Vexp on the vertical axis and Iexp on the horizontal axis. [Figure 8] 1 is a graph obtained in Example 1, with the vertical axis being y and the horizontal axis being x. [Figure 9] 1 shows the change in the minimum value of the normalized radius of curvature R calculated in a graph with the horizontal axis x and the vertical axis y, obtained in Example 1. [Figure 10] 1 is a graph obtained in Example 1, with the vertical axis representing R and the horizontal axis representing x. DETAILED DESCRIPTION OF THE INVENTION

[0012] The present invention will be described in detail below with reference to preferred embodiments. The electrophotographic apparatus according to the present invention comprises an electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member, image exposure means for irradiating the surface of the electrophotographic photosensitive member with image exposure light to form an electrostatic latent image on the surface of the electrophotographic photosensitive member, developing means for developing the electrostatic latent image with toner to form a toner image on the surface of the electrophotographic photosensitive member, transfer means for transferring the toner image from the surface of the electrophotographic photosensitive member to a transfer material, charge transfer amount detection means for detecting the amount of charge transfer per unit time due to discharge to the electrophotographic photosensitive member, and a detection means for detecting the amount of charge transfer per unit time due to discharge to the electrophotographic photosensitive member. Therefore, the electrophotographic photosensitive member is charged, and the image exposure means performs image exposure on the electrophotographic photosensitive member with a light amount at at least one point weaker than the light amount showing the minimum value of the normalized radius of curvature R of the electrophotographic photosensitive member, which is expressed by the following formula (E1), and with a light amount at at least two points stronger than the light amount showing the minimum value of the normalized radius of curvature R, and the charge transfer amount detection means detects the amount of charge transfer per unit time to the electrophotographic photosensitive member when the exposed portion is charged, and the electrophotographic apparatus has an exposed portion potential control means for controlling the potential of the exposed portion of the electrophotographic photosensitive member based on the detection result, The electrophotographic photoreceptor is At a temperature of 23.5°C and a relative humidity of 50%RH, (1) setting the surface potential of the electrophotographic photosensitive member to 0 [V]; (2) charging the electrophotographic photosensitive member for 0.005 seconds so that the absolute value of the initial surface potential of the electrophotographic photosensitive member becomes 500 [V]; (3) 0.02 seconds after the start of charging, the wavelength is 805 [nm] and the intensity is 25 [mW / cm 2 ] light for t seconds continuously. exp [μJ / cm 2 ] light, (4) The absolute value of the surface potential of the electrophotographic photosensitive member after exposure, measured 0.06 seconds after the start of charging, is V exp When [V] is used, Measurements (1) to (4) are performed by changing t. exp to 0.000 [μJ / cm 2 ] to 1.000 [μJ / cm 2 ] up to 0.001 [μJ / cm 2 ] and repeat the process. The horizontal axis is I expThe vertical axis is V exp In a graph where V of the graph exp = 250[V], the amount of light when 1 / 2 [μJ / cm 2 ], 10·I 1 / 2 The horizontal axis I exp The normalized light intensity is x, and the value 500 [V] on the vertical axis of the graph (x=0) is 1, and the value when x=1 is 0. exp When the normalized surface potential is y, In a graph with the horizontal axis x and the vertical axis y, the minimum value of the normalized radius of curvature R calculated by the following formula (E1) is 0.24 or less.

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[0013] The charge transfer amount per unit time detection means is a simple device that utilizes a current detection function built into a high-voltage power supply (shown in FIG. 2) provided in an electrophotographic apparatus as a charging means for charging an electrophotographic photosensitive member. Specifically, the electrophotographic photosensitive member is charged by the charging means, and the imagewise exposure means performs imagewise exposure on the electrophotographic photosensitive member with at least one light intensity weaker than the light intensity that indicates the minimum value of the normalized radius of curvature R, as expressed by the following formula (E1): and then imagewise exposure on the electrophotographic photosensitive member with at least two light intensity points stronger than the minimum value of the normalized radius of curvature. That is, a latent image as shown in FIGS. 3 and 4 is formed on the photosensitive member. In other words, by performing imagewise exposure on at least three points with different light intensities, three electrostatic latent image patterns are formed (the number of exposure points and the pattern can be controlled as desired). The exposed areas are then charged by the charging means, and the current flowing through the exposed areas and the charge transfer amount per unit time are measured using the current detection function (charge transfer amount detection means) of the high-voltage power supply. The detection results are graphed as shown in Figure 5, and the light intensity at the intersection is determined to determine the image exposure (detect the light intensity, determine the detected light intensity), allowing the exposed area potential to be controlled. In order to perform detection more quickly and accurately, it is preferable to have fewer exposure points.

[0014] The detection means is achieved by using the following characteristics of the electrophotographic photosensitive member. At a temperature of 23.5°C and a relative humidity of 50%RH, (1) setting the surface potential of the electrophotographic photosensitive member to 0 [V]; (2) charging the electrophotographic photosensitive member for 0.005 seconds so that the absolute value of the initial surface potential of the electrophotographic photosensitive member becomes 500 [V]; (3) 0.02 seconds after the start of charging, the wavelength is 805 [nm] and the intensity is 25 [mW / cm 2 ] light for t seconds continuously. exp [μJ / cm 2 ] light, (4) The absolute value of the surface potential measured 0.06 seconds after the start of charging is V exp When [V] is used, Measurements (1) to (4) are performed by changing t. exp to 0.000 [μJ / cm 2 ] to 1.000 [μJ / cm 2 ] up to 0.001 [μJ / cm 2 ] and repeat the process. The horizontal axis is I exp The vertical axis is V exp In a graph where V of the graph exp = 250[V], the amount of light when 1 / 2 [μJ / cm 2 ], 10·I 1 / 2 The horizontal axis I exp The normalized light intensity is x, and the vertical axis V is set so that the value 500 [V] of the graph is 1 and the value when x = 1 is 0. exp When the normalized surface potential is y, In a graph with the horizontal axis x and the vertical axis y, the minimum value of the normalized radius of curvature R calculated by the following formula (E1) is 0.24 or less.

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[0015] When the minimum value of the normalized radius of curvature R of an electrophotographic photosensitive member is 0.24 or less, as shown in the graphs in FIGS. 5 and 6, the result of the charge transfer amount detection means and the image exposure amount in the actual EV result of the electrophotographic photosensitive member (hereinafter also referred to as the "EV curve") match at the point where the normalized radius of curvature R takes the minimum value. Therefore, by combining the detecting means and the electrophotographic photosensitive member, the potential of the exposed portion can be controlled with high precision in a short time. In addition, when the minimum value of the normalized radius of curvature R is 0.21 or less, it is possible to control with high precision in a short time. The EV curve is a function of the exposure amount I to the photosensitive member. exp [μJ / cm 2 ] and the absolute value of the surface potential at that time V exp This refers to the relationship between [V].

[0016] [EV curve evaluation method for electrophotographic photoreceptors] Here, the method for measuring the EV curve in the present invention will be described. First, a transparent quartz glass is prepared (hereinafter referred to as "NESA glass") that has been optically polished and completely made transparent, with an ITO film vapor-deposited on the surface as a transparent ITO electrode so that the surface has a sheet resistance of 1,000 [Ω / sq] or less. The surface of the photosensitive body is then brought into close contact with this NESA glass. In this case, smooth NESA glass is used if the photosensitive body is flat, and curved NESA glass is used if the photosensitive body is cylindrical. In this state, the surface of the photosensitive body can be charged by applying a voltage from a high-voltage power supply to the NESA glass. In addition, a voltage of 805 [nm] wavelength and 25 [mW / cm] intensity is applied from the underside of the NESA glass. 2 By irradiating the photosensitive member surface with planar light, the surface potential can be optically attenuated.

[0017] By using the above measurement system, the exposure light of 25 mW / cm is stronger than the exposure light irradiated on the photosensitive body in electrophotographic devices that are expected to be used in the future. 2 ] is irradiated to the photosensitive member once for a short time, while at the same time repeating charging and exposure in a cycle faster than the process speed of electrophotographic devices currently in use or expected in the future. This allows for a light intensity of 0.001 [μJ / cm 2], a large amount of data can be stably and easily acquired to obtain the EV curve of the photoconductor of the present invention. At the same time, the above measurement method realized using this measurement system makes it possible to evaluate the photoconductor characteristics that can cope with the shortening of exposure irradiation time due to the recent and future increase in process speed, and the reduction in the number of exposures when the exposure method changes from the currently mainstream laser scanning optical system to an LED array. In particular, when the intensity is 25 [mW / cm 2 The light irradiation conditions of a short time and one exposure at ] are a sufficiently strict EV curve measurement method that will remain in place for the future in light of the reciprocity law failure characteristics of photoconductors.

[0018] Also, The electrophotographic photoreceptor is At a temperature of 23.5°C and a relative humidity of 50%RH, (1) setting the surface potential of the electrophotographic photosensitive member to 0 [V]; (2) charging the electrophotographic photosensitive member for 0.005 seconds so that the absolute value of the initial surface potential becomes 500 [V]; (3) 0.02 seconds after the start of charging, the wavelength is 805 [nm] and the intensity is 25 [mW / cm 2 ] light for t seconds continuously. exp [μJ / cm 2 ] light, (4) The absolute value of the surface potential of the electrophotographic photosensitive member after exposure, measured 0.06 seconds after the start of charging, is V exp When [V] is used, Measurements (1) to (4) are performed by changing t. exp to 0.000 [μJ / cm 2 ] to 1.000 [μJ / cm 2 ] up to 0.001 [μJ / cm 2 ] and repeat the process. The horizontal axis is I exp The vertical axis is V exp In a graph where The normalized light intensity x when the normalized surface potential y of the graph becomes 0.5 is Is 0.5 [μJ / cm 2 ], light intensity Is 0.5 4 times the light intensity of 4Is 0.5 [μJ / cm 2], and 5 times the light intensity 5Is 0.5 [μJ / cm 2 ] and x=4Is 0.5 When y=y4, x=5Is 0.5 If y is y5, The slopes S2 and S3 calculated by the following formulas (E2) and (E3) satisfy S2≧3.0 and S3≦0.41. It is characterized by:

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[0019] By combining the detecting means with the electrophotographic photosensitive member, the potential of the exposed portion can be controlled with high precision in a short time. Furthermore, when the slope S3 is more preferably 0.21 or less, the potential can be controlled with high precision in a short time. Furthermore, when S3 is even more preferably 0.15 or less, the potential can be controlled with even higher precision in a short time.

[0020] Furthermore, in the electrophotographic apparatus of the present invention, it is more preferable that the exposed portion potential control means is a means that performs image exposure by the image exposure means with a light amount at least n points (n is an integer of 2 or more) weaker than the light amount that shows the minimum value of the normalized radius of curvature R of the electrophotographic photosensitive member and a light amount at least m points (m is an integer of 3 or more) stronger than the light amount that shows the minimum value of the normalized radius of curvature R, detects the amount of charge transfer per unit time to the electrophotographic photosensitive member when the exposed portion is charged, and controls the exposed portion potential of the electrophotographic photosensitive member based on the detection result,

[0021] [Electrophotographic photoreceptor] The electrophotographic photoreceptor according to the present invention has a support and a photosensitive layer formed on the support. Fig. 1 is a diagram showing an example of the layer structure of an electrophotographic photoreceptor. In Fig. 1, 101 is a support, 102 is an undercoat layer, 103 is a charge generation layer, 104 is a charge transport layer, and 105 is a photosensitive layer (laminated photosensitive layer).

[0022] <Support> In the present invention, the support is preferably a conductive support having electrical conductivity. Examples of the conductive support include a support formed of a metal or alloy such as aluminum, iron, nickel, copper, or gold, and a support having a thin film of a metal such as aluminum, chromium, silver, or gold, a thin film of a conductive material such as indium oxide, tin oxide, or zinc oxide, or a thin film of a conductive ink containing silver nanowires formed on an insulating support such as a polyester resin, a polycarbonate resin, a polyimide resin, or glass. The surface of the support may be subjected to electrochemical treatment such as anodization, wet honing, blasting, cutting, etc. in order to improve electrical properties and suppress interference fringes. The shape of the support may be cylindrical or film-like.

[0023] <Conductive layer> In the electrophotographic photoreceptor according to the present invention, a conductive layer may be provided on the support. By providing the conductive layer, it is possible to cover unevenness and defects of the support and prevent interference fringes. The average thickness of the conductive layer is preferably 5 μm or more and 40 μm or less, and more preferably 10 μm or more and 30 μm or less.

[0024] The conductive layer preferably contains conductive particles and a binder resin. Examples of the conductive particles include carbon black, metal particles, and metal oxide particles. Examples of the metal oxides include zinc oxide, aluminum oxide, indium oxide, silicon oxide, zirconium oxide, tin oxide, titanium oxide, magnesium oxide, antimony oxide, and bismuth oxide. Examples of the metals include aluminum, nickel, iron, nichrome, copper, zinc, and silver. Among these, it is preferable to use metal oxides as the conductive particles, and it is particularly preferable to use titanium oxide, tin oxide, or zinc oxide.

[0025] When metal oxides are used as conductive particles, the surfaces of the metal oxides may be treated with a silane coupling agent or the like, or the metal oxides may be doped with elements such as phosphorus or aluminum or their oxides, such as phosphorus, aluminum, niobium, and tantalum. The conductive particles may have a laminated structure including a core particle and a coating layer covering the core particle. Examples of the core particle include titanium oxide, barium sulfate, and zinc oxide. Examples of the coating layer include metal oxides such as tin oxide and titanium oxide. When metal oxide particles are used as the conductive particles, the volume average particle size is preferably 1 nm or more and 500 nm or less, and more preferably 3 nm or more and 400 nm or less.

[0026] Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, and alkyd resin. The conductive layer may further contain silicone oil, resin particles, a masking agent such as titanium oxide, and the like.

[0027] The average thickness of the conductive layer is preferably 1 μm or more and 50 μm or less, and particularly preferably 3 μm or more and 40 μm or less.

[0028] The conductive layer can be formed by preparing a coating solution for the conductive layer containing the above-mentioned materials and solvent, forming a coating film from this, and drying it. Examples of solvents used in the coating solution include alcohol-based solvents, sulfoxide-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Examples of dispersion methods for dispersing the conductive particles in the coating solution for the conductive layer include methods using a paint shaker, a sand mill, a ball mill, and a liquid collision-type high-speed disperser.

[0029] <Undercoat layer> The electrophotographic photoreceptor according to the present invention is preferably used when an undercoat layer is provided between the support and the charge generating layer. The undercoat layer preferably contains a polyamide resin and metal oxide particles. The metal oxide particles are preferably titanium oxide particles. The polyamide resin is preferably a polyamide resin soluble in an alcohol-based solvent. For example, ternary (6-66-610) copolymer polyamide, quaternary (6-66-610-12) copolymer polyamide, N-methoxymethylated nylon, polymerized fatty acid polyamide, polymerized fatty acid polyamide block copolymer, copolymer polyamide containing a diamine component, etc. are preferably used.

[0030] From the viewpoint of suppressing charge accumulation, the titanium oxide particles preferably have a rutile or anatase crystal structure, and more preferably the rutile type, which has weaker photocatalytic activity. If the titanium oxide particles are rutile, the rutile content is preferably 90% or more. The titanium oxide particles are preferably spherical, and from the viewpoint of suppressing charge accumulation and achieving uniform dispersibility, the average primary particle size is preferably 10 nm or more and 100 nm or less, and more preferably 30 nm or more and 60 nm or less. From the viewpoint of achieving uniform dispersibility, the titanium oxide particles may be treated with a silane coupling agent or the like.

[0031] In addition to the polyamide resin and titanium oxide particles, the undercoat layer of the present invention may contain additives such as organic particles and a leveling agent for the purpose of improving the film-forming properties of the undercoat layer of the electrophotographic photoreceptor, provided that the content of the additives in the undercoat layer is preferably 10% by mass or less based on the total mass of the undercoat layer.

[0032] The average thickness of the undercoat layer is preferably 0.5 μm or more and 3.0 μm or less. When the thickness of the undercoat layer is 3.0 μm or less, the effect of suppressing charge accumulation is enhanced. When the thickness is less than 0.5 μm, leakage is likely to occur due to a local decrease in charging performance.

[0033] The relationship between the charge generating material used in the charge generating layer (to be described later) and the undercoat layer is preferably as follows. In the case of a hydroxygallium phthalocyanine pigment, the arithmetic mean roughness Ra and the average length of the roughness curve elements Rsm of the undercoat layer surface, as defined in JIS B0601:2001, preferably satisfy the formula (A) Ra≦50 nm and the formula (B) 0.1≦Ra / Rsm≦0.5. If Ra is greater than 50 nm or Ra / Rsm is less than 0.1, the scale of the recesses in the undercoat layer becomes larger than the scale of the hydroxygallium phthalocyanine pigment particles, reducing the contact area, slowing the transfer of generated charges and preventing the effect of reducing the normalized radius of curvature. From the perspective of normalized radius of curvature, Ra is preferably 30 nm or less. If Ra / Rsm is greater than 0.5, the recesses in the undercoat layer become deeper, preventing the hydroxygallium phthalocyanine pigment particles from penetrating into the recesses. Furthermore, the binder resin penetrates between the undercoat layer and the hydroxygallium phthalocyanine pigment particles, reducing the contact area and preventing the effect of reducing the normalized radius of curvature from being fully achieved.

[0034] In the case of titanyl phthalocyanine pigment particles, the arithmetic mean roughness Ra and the average length of the roughness curve elements Rsm of the undercoat layer surface, as defined in JIS B0601:2001, preferably satisfy the following formulas: (A) Ra≦120 nm and (B) 0.1≦Ra / Rsm≦0.5. If Ra is greater than 120 nm or Ra / Rsm is less than 0.1, the scale of the recesses in the undercoat layer becomes larger than that of the titanyl phthalocyanine pigment particles, reducing the contact area and slowing the transfer of generated charges, thereby preventing the effect of reducing the normalized radius of curvature. From the perspective of suppressing transfer memory, Ra is preferably 100 nm or less. If Ra / Rsm is greater than 0.5, the recesses in the undercoat layer become deeper, preventing the titanyl phthalocyanine pigment particles from penetrating the recesses. Furthermore, the binder resin penetrates between the undercoat layer and the titanyl phthalocyanine pigment particles, reducing the contact area and slowing the transfer of generated charges, preventing the effect of reducing the normalized radius of curvature.

[0035] The undercoat layer can be formed by preparing a coating solution for the undercoat layer containing the above-mentioned materials and solvent, forming a coating film from the coating solution, and drying and / or curing the coating film. Examples of solvents used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Examples of dispersion methods for dispersing titanium oxide particles in the coating solution for the undercoat layer include ultrasonic dispersion, methods using a paint shaker, a sand mill, a ball mill, and a liquid collision-type high-speed disperser.

[0036] <Charge generation layer> In the electrophotographic photoreceptor according to the present invention, a charge generation layer is preferably provided immediately on the undercoat layer. The charge generation layer of the electrophotographic photoreceptor according to the present invention can be obtained by dispersing a phthalocyanine pigment as a charge generation material and, if necessary, a binder resin in a solvent to prepare a coating liquid for the charge generation layer, forming a coating film of the coating liquid for the charge generation layer, and drying the coating film.

[0037] The coating liquid for the charge generating layer may be prepared by adding only the charge generating material to a solvent and dispersing the material, followed by adding a binder resin, or by adding the charge generating material and the binder resin together to a solvent and dispersing the material. For the dispersion, a media type disperser such as a sand mill or a ball mill, or a liquid collision type disperser or an ultrasonic disperser can be used.

[0038] Examples of binder resins used in the charge generating layer include resins (insulating resins) such as polyvinyl butyral resins, polyvinyl acetal resins, polyarylate resins, polycarbonate resins, polyester resins, polyvinyl acetate resins, polysulfone resins, polystyrene resins, phenoxy resins, acrylic resins, phenoxy resins, polyacrylamide resins, polyvinylpyridine resins, urethane resins, agarose resins, cellulose resins, casein resins, polyvinyl alcohol resins, polyvinylpyrrolidone resins, vinylidene chloride resins, acrylonitrile copolymers, and polyvinyl benzal resins. Organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinyl anthracene, and polyvinylpyrene can also be used. The binder resins may be used alone or in combination of two or more types as a mixture or copolymer.

[0039] Examples of solvents used in the charge generating layer coating solution include toluene, xylene, tetralin, chlorobenzene, dichloromethane, chloroform, trichloroethylene, tetrachloroethylene, carbon tetrachloride, methyl acetate, ethyl acetate, propyl acetate, methyl formate, ethyl formate, acetone, methyl ethyl ketone, cyclohexanone, diethyl ether, dipropyl ether, propylene glycol monomethyl ether, dioxane, methylal, tetrahydrofuran, water, methanol, ethanol, n-propanol, isopropanol, butanol, methyl cellosolve, methoxypropanol, dimethylformamide, dimethylacetamide, and dimethyl sulfoxide. Solvents may be used alone or in combination. The charge generating layer preferably has a thickness of 0.10 μm to 1.00 μm, more preferably 0.16 μm to 0.40 μm.

[0040] (phthalocyanine pigment) In the present invention, the charge generating material preferably contains a hydroxygallium phthalocyanine pigment, which may have an axial ligand or a substituent. In the present invention, the hydroxygallium phthalocyanine pigment has crystal particles of a crystal type that exhibits peaks at Bragg angles 2θ of 7.4°±0.3° and 28.2°±0.3° in an X-ray diffraction spectrum using CuKα radiation, and the crystal particle size distribution measured using small-angle X-ray scattering is preferably 30 nm to 50 nm, with the half-width of the peak being 50 nm or less.

[0041] Furthermore, it is more preferable that the hydroxygallium phthalocyanine pigment has crystal particles that contain an amide compound represented by the following formula (A1) within the particle: Examples of the amide compound represented by formula (A1) include N-methylformamide, N-propylformamide, and N-vinylformamide. [ka] (In the above formula (A1), R 1 represents a methyl group, a propyl group, or a vinyl group.

[0042] The content of the amide compound represented by formula (A1) contained in the crystal particles is preferably 0.1% by mass to 3.0% by mass, more preferably 0.1% by mass to 1.4% by mass, based on the total mass of the crystal particles. By setting the content of the amide compound to 0.1% by mass to 3.0% by mass, the crystal particles can be made to have an appropriate uniform size.

[0043] The phthalocyanine pigment containing the amide compound represented by formula (A1) in its crystal particles can be obtained by a step of converting the crystal structure of a phthalocyanine pigment obtained by an acid pasting method and the amide compound represented by formula (A1) by wet milling treatment. When a dispersant is used in the milling treatment, the amount of the dispersant is preferably 10 to 50 times the mass of the phthalocyanine pigment. Examples of the solvent that can be used include amide solvents such as N,N-dimethylformamide, N,N-dimethylacetamide, the compound represented by formula (A1), N-methylacetamide, and N-methylpropioamide, halogenated solvents such as chloroform, ether solvents such as tetrahydrofuran, and sulfoxide solvents such as dimethyl sulfoxide. The amount of the solvent used is preferably 5 to 30 times the mass of the phthalocyanine pigment.

[0044] Furthermore, the present inventors have found that when attempting to obtain the crystalline phthalocyanine pigment used in the present invention through a crystal conversion process, using an amide compound represented by the above formula (A1) as a solvent increases the time required for crystal conversion. Specifically, when N-methylformamide is used as a solvent, the time required for crystal conversion increases several times compared to when N,N-dimethylformamide is used. The long time required for crystal conversion provides time for the crystal particle size to be made uniform to a certain degree before the crystal conversion is completed, making it easier to obtain the above phthalocyanine pigment.

[0045] Whether or not the hydroxygallium phthalocyanine pigment contains the amide compound represented by formula (A1) in its crystal particles was determined by analyzing the data from 1H-NMR measurements of the resulting hydroxygallium phthalocyanine pigment. Furthermore, the content of the amide compound represented by formula (A1) in the crystal particles was determined by analyzing the results of the 1H-NMR measurements. For example, when a milling treatment using a solvent capable of dissolving the amide compound represented by formula (A1) or a washing step after milling was performed, the resulting hydroxygallium phthalocyanine pigment was subjected to 1H-NMR measurements. If the amide compound represented by formula (A1) was detected, it could be determined that the amide compound represented by formula (A1) was contained in the crystals.

[0046] When the phthalocyanine pigment is obtained by centrifugation, the weight ratio of the phthalocyanine pigment to the binder resin in the mixed solution must be measured in order to control the ratio P of the volume of the charge generating material to the total volume of the charge generating layer. The weight ratio in the mixed solution of the phthalocyanine pigment and the binder resin was determined by analyzing data from 1H-NMR measurements. For example, when a hydroxygallium phthalocyanine pigment is used as the phthalocyanine pigment and polyvinyl butyral is used as the binder resin, the weight ratio can be determined by comparing the peaks derived from the hydroxygallium phthalocyanine pigment and the peaks derived from the polyvinyl butyral in the 1H-NMR measurement data.

[0047] In the present invention, titanyl phthalocyanine pigments are also preferably used as charge-generating materials. The titanyl phthalocyanine pigments preferably have crystal grains with a crystal type that exhibits peaks at Bragg angles 2θ of 9.8°±0.3° and 27.1°±0.3° in an X-ray diffraction spectrum using CuKα radiation, and have a peak in the crystal grain size distribution measured by small-angle X-ray scattering of 50 nm to 150 nm, with the half-width of the peak being 100 nm or less.

[0048] The powder X-ray diffraction measurement and 1H-NMR measurement of the phthalocyanine pigment contained in the electrophotographic photosensitive member of the present invention were carried out under the following conditions. (Powder X-ray diffraction measurement) Measuring equipment used: Rigaku Electric Co., Ltd., X-ray diffraction equipment RINT-TTRII X-ray tube:Cu X-ray wavelength: Kα1 Tube voltage: 50KV Tube current: 300mA Scanning method: 2θ scan Scan speed: 4.0° / min Sampling interval: 0.02° Starting angle 2θ: 5.0° Stop angle 2θ: 35.0° Goniometer: Rotor horizontal goniometer (TTR-2) Attachment: Capillary rotating sample stage Filter: None Detector: Scintillation counter Incident Monochrome: Use Slit: Variable slit (parallel beam method) Counter monochromator: Not used Divergence slit: open Divergence vertical limit slit: 10.00 mm Scattering slit: open Receiving slit: open (1H-NMR measurement) Measuring instrument used: AVANCEIII 500 manufactured by BRUKER Solvent: Bisulfuric acid (D2SO4) Accumulation count: 2,000

[0049] <Charge transport layer> The charge transport layer preferably contains a charge transport material and a resin.

[0050] Examples of the charge transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these materials. Among these, triarylamine compounds and benzidine compounds are preferred. The content of the charge transport material in the charge transport layer is preferably 25% by mass to 70% by mass, and more preferably 30% by mass to 55% by mass, based on the total mass of the charge transport layer.

[0051] Examples of the resin include polyester resin, polycarbonate resin, acrylic resin, polystyrene resin, etc. Among these, polycarbonate resin and polyester resin are preferred. As the polyester resin, polyarylate resin is particularly preferred. The content ratio (mass ratio) of the charge transport material to the resin is preferably 4:10 to 20:10, and more preferably 5:10 to 12:10.

[0052] The charge transport layer may also contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slipping agents, and abrasion resistance improvers. Specific examples of such additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles.

[0053] The average thickness of the charge transport layer is preferably from 5 μm to 50 μm, more preferably from 8 μm to 40 μm, and particularly preferably from 10 μm to 30 μm.

[0054] The charge transport layer can be formed by preparing a coating solution for the charge transport layer containing the above-mentioned materials and solvent, forming a coating film from the coating solution, and drying the coating film. Examples of the solvent used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, ether-based solvents and aromatic hydrocarbon-based solvents are preferred.

[0055] <Protective layer> In the present invention, a protective layer may be provided on the photosensitive layer, which can improve durability.

[0056] The protective layer preferably contains conductive particles and / or a charge transport material, and a resin. Examples of conductive particles include particles of metal oxides such as titanium oxide, zinc oxide, tin oxide, and indium oxide. Examples of the charge transport material include polycyclic aromatic compounds, heterocyclic compounds, hydrazone compounds, styryl compounds, enamine compounds, benzidine compounds, triarylamine compounds, and resins having groups derived from these materials. Among these, triarylamine compounds and benzidine compounds are preferred. Examples of the resin include polyester resin, acrylic resin, phenoxy resin, polycarbonate resin, polystyrene resin, phenol resin, melamine resin, epoxy resin, etc. Among these, polycarbonate resin, polyester resin, and acrylic resin are preferred.

[0057] The protective layer may also be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group. Examples of the reaction include thermal polymerization, photopolymerization, and radiation-induced polymerization. Examples of the polymerizable functional group possessed by the monomer having a polymerizable functional group include an acrylic group and a methacrylic group. A material having charge transport capability may also be used as the monomer having a polymerizable functional group.

[0058] The protective layer may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slipping agents, and abrasion resistance improvers. Specific examples of such additives include hindered phenol compounds, hindered amine compounds, sulfur compounds, phosphorus compounds, benzophenone compounds, siloxane-modified resins, silicone oils, fluororesin particles, polystyrene resin particles, polyethylene resin particles, silica particles, alumina particles, and boron nitride particles.

[0059] The average thickness of the protective layer is preferably 0.5 μm or more and 10 μm or less, and more preferably 1 μm or more and 7 μm or less.

[0060] The protective layer can be formed by preparing a coating solution for the protective layer containing the above-mentioned materials and solvent, forming a coating film from the coating solution, and drying and / or curing the coating film. Examples of the solvent used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, sulfoxide-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0061] [Process cartridge and electrophotographic device] An example of the schematic configuration of an electrophotographic apparatus having a process cartridge equipped with an electrophotographic photosensitive member is shown in Figure 2. In Figure 2, reference numeral 1 denotes a cylindrical (drum-shaped) electrophotographic photosensitive member, which is driven to rotate around an axis 2 in the direction of the arrow at a predetermined peripheral speed (process speed).

[0062] During rotation, the surface of the electrophotographic photosensitive member 1 is charged to a predetermined positive or negative potential by a charging means 3 connected to a high-voltage power supply 13 of the electrophotographic apparatus. Next, exposure light 4 is irradiated from an exposure means (not shown) onto the charged surface of the electrophotographic photosensitive member 1, and an electrostatic latent image corresponding to the target image information is formed. The image exposure light 4 is light that is intensity-modulated in accordance with a time-series electric digital image signal of the target image information, output from an exposure means such as a slit exposure or laser beam scanning exposure.

[0063] The electrostatic latent image formed on the surface of the electrophotographic photosensitive member 1 is developed (normal development or reversal development) with toner contained in the developing means 5, and a toner image is formed on the surface of the electrophotographic photosensitive member 1. The toner image formed on the surface of the electrophotographic photosensitive member 1 is transferred to a transfer material 7 by a transfer means 6. At this time, a bias voltage of a polarity opposite to that of the charge held by the toner is applied to the transfer means 6 from a bias power supply (not shown). Furthermore, if the transfer material 7 is paper, the transfer material 7 is taken out from a paper feed unit (not shown) and fed between the electrophotographic photosensitive member 1 and the transfer means 6 in synchronization with the rotation of the electrophotographic photosensitive member 1.

[0064] The transfer material 7, onto which the toner image has been transferred from the electrophotographic photoreceptor 1, is separated from the surface of the electrophotographic photoreceptor 1 and transported to a fixing means 8, where the toner image is fixed and printed out as an image-formed product (print, copy) outside the electrophotographic device. After the toner image has been transferred to the transfer material 7, the surface of the electrophotographic photoreceptor 1 is cleaned by a cleaning means 9 to remove any adhering matter, such as toner (residual toner). Recently developed cleanerless systems allow the residual toner to be removed directly by a developing device or the like. Furthermore, the surface of the electrophotographic photoreceptor 1 is neutralized with pre-exposure light 10 from a pre-exposure means (not shown) before being used for repeated image formation. Note that if the charging means 3 is a contact charging means using a charging roller or the like, the pre-exposure means is not necessarily required. In the present invention, a process cartridge is formed by housing and integrally supporting multiple components, such as the electrophotographic photoreceptor 1, charging means 3, developing means 5, and cleaning means 9, in a container. This process cartridge can be configured to be detachable from the main body of the electrophotographic device. For example, at least one selected from the charging means 3, the developing means 5, and the cleaning means 9 is integrally supported together with the electrophotographic photosensitive member 1 to form a cartridge. A process cartridge 11 can be formed that is detachably attached to the main body of the electrophotographic apparatus using guide means 12 such as rails on the main body of the electrophotographic apparatus. When the electrophotographic apparatus is a copier or printer, the exposure light 4 may be reflected light or transmitted light from an original. Alternatively, the exposure light 4 may be light emitted by scanning a laser beam, driving an LED array, or driving a liquid crystal shutter array in accordance with a signal obtained by reading the original with a sensor and converting it into a signal.

[0065] The electrophotographic photoreceptor 1 of the present invention can be widely applied to electrophotographic application fields such as laser beam printers, CRT printers, LED printers, FAX machines, liquid crystal printers, and laser plate making. [Example]

[0066] The present invention will be described in more detail below using photoreceptor manufacturing examples. The present invention is not limited to the following examples unless it exceeds the gist of the present invention. In the following description of the photoreceptor manufacturing examples, "parts" are based on mass unless otherwise specified.

[0067] The film thickness of each layer of the electrophotographic photoreceptor in the photoreceptor manufacturing examples, except for the charge generation layer, was determined by a method using an eddy current film thickness meter (Fischerscope, manufactured by Fisher Instruments) or by a method converting the mass per unit area into specific gravity. The film thickness of the charge generation layer was determined by measuring the Macbeth density value of the photoreceptor using a spectrodensitometer (trade name: X-Rite504 / 508, manufactured by X-Rite) pressed against the surface of the photoreceptor and converting the Macbeth density value using a calibration curve previously obtained from the film thickness measurement value obtained by observing a cross-sectional SEM image.

[0068] [Preparation example of coating solution 1 for undercoat layer] 100 parts of rutile-type titanium dioxide particles (average primary particle size: 50 nm, manufactured by Teika) were mixed with 500 parts of toluene and stirred, and 3.0 parts of methyldimethoxysilane ("TSL8117" manufactured by Toshiba Silicones) was added and stirred for 8 hours. Thereafter, the toluene was distilled off under reduced pressure, and the mixture was dried at 120°C for 3 hours to obtain rutile-type titanium dioxide particles that had been surface-treated with methyldimethoxysilane. A dispersion was prepared by adding 18 parts of the methyldimethoxysilane-surface-treated rutile-type titanium dioxide particles, 4.5 parts of N-methoxymethylated nylon (product name: Toresin EF-30T, manufactured by Nagase ChemteX), and 1.5 parts of copolymer nylon resin (product name: Amilan CM8000, manufactured by Toray) to a mixed solvent of 90 parts of methanol and 60 parts of 1-butanol. This dispersion was dispersed for 6 hours using glass beads with a diameter of 1.0 mm in a vertical sand mill. The sand mill-dispersed solution was then further dispersed for 1 hour in an ultrasonic disperser (UT-205, manufactured by Sharp) to prepare coating solution 1 for the undercoat layer. The output of the ultrasonic disperser was set to 100%. No media such as glass beads were used in this milling process.

[0069] [Preparation example of coating solution 2 for undercoat layer] Coating solution 2 for undercoat layer was prepared in the same manner as in the preparation example of coating solution 1 for undercoat layer, except that the sand mill dispersion treatment time was changed to 4 hours.

[0070] [Preparation example of coating solution 3 for undercoat layer] 100 parts of rutile-type titanium dioxide particles (average primary particle size: 15 nm, manufactured by Teika) were mixed with 500 parts of toluene and stirred, to which 9.6 parts of methyldimethoxysilane ("TSL8117" manufactured by Toshiba Silicones) was added, followed by stirring for 8 hours. The toluene was then removed by distillation under reduced pressure, and the mixture was dried at 120°C for 3 hours to obtain rutile-type titanium dioxide particles that had been surface-treated with methyldimethoxysilane. A dispersion was prepared by adding 6 parts of the methyldimethoxysilane-surface-treated rutile-type titanium dioxide particles, 4.5 parts of N-methoxymethylated nylon (product name: Toresin EF-30T, manufactured by Nagase ChemteX), and 1.5 parts of copolymer nylon resin (product name: Amilan CM8000, manufactured by Toray) to a mixed solvent of 90 parts of methanol and 60 parts of 1-butanol. This dispersion was dispersed for 6 hours using glass beads with a diameter of 1.0 mm in a vertical sand mill. The sand mill-dispersed solution was then further dispersed for 1 hour in an ultrasonic disperser (UT-205, manufactured by Sharp) to prepare coating solution 3 for the undercoat layer. The output of the ultrasonic disperser was set to 100%. No media such as glass beads were used in this milling process.

[0071] [Preparation example of coating solution 4 for undercoat layer] Coating solution 4 for undercoat layer was prepared in the same manner as in the preparation example of coating solution 3 for undercoat layer, except that the sand mill dispersion treatment time was changed to 4 hours.

[0072] [Preparation example of coating solution 5 for undercoat layer] 100 parts of rutile-type titanium dioxide particles (average primary particle size: 35 nm, manufactured by Teika) were mixed with 500 parts of toluene and stirred, and 4.32 parts of methyldimethoxysilane ("TSL8117" manufactured by Toshiba Silicones) was added and stirred for 8 hours. Thereafter, the toluene was distilled off under reduced pressure, and the mixture was dried at 120°C for 3 hours to obtain rutile-type titanium dioxide particles that had been surface-treated with methyldimethoxysilane. A dispersion was prepared by adding 12 parts of the methyldimethoxysilane-surface-treated rutile-type titanium dioxide particles, 4.5 parts of N-methoxymethylated nylon (product name: Toresin EF-30T, manufactured by Nagase ChemteX), and 1.5 parts of copolymer nylon resin (product name: Amilan CM8000, manufactured by Toray) to a mixed solvent of 90 parts of methanol and 60 parts of 1-butanol. This dispersion was dispersed for 6 hours using glass beads with a diameter of 1.0 mm in a vertical sand mill. The sand mill-dispersed solution was then further dispersed for 1 hour in an ultrasonic disperser (UT-205, manufactured by Sharp) to prepare coating solution 5 for the undercoat layer. The output of the ultrasonic disperser was set to 100%. No media such as glass beads were used in this milling process.

[0073] [Preparation example of coating solution 6 for undercoat layer] Coating Solution 6 for Undercoat Layer was prepared in the same manner as in Preparation Example of Coating Solution 5 for Undercoat Layer, except that the sand mill dispersion treatment time was changed to 4 hours.

[0074] [Preparation example of coating solution 7 for undercoat layer] 100 parts of rutile-type titanium dioxide particles (average primary particle size: 80 nm, manufactured by Teika) were mixed with 500 parts of toluene and stirred, and 1.8 parts of methyldimethoxysilane ("TSL8117" manufactured by Toshiba Silicones) was added and stirred for 8 hours. Thereafter, the toluene was distilled off under reduced pressure, and the mixture was dried at 120°C for 3 hours to obtain rutile-type titanium dioxide particles that had been surface-treated with methyldimethoxysilane. A dispersion was prepared by adding 18 parts of the methyldimethoxysilane-surface-treated rutile-type titanium dioxide particles, 4.5 parts of N-methoxymethylated nylon (product name: Toresin EF-30T, manufactured by Nagase ChemteX), and 1.5 parts of copolymer nylon resin (product name: Amilan CM8000, manufactured by Toray Industries, Inc.) to a mixed solvent of 90 parts of methanol and 60 parts of 1-butanol. This dispersion was dispersed for 6 hours using glass beads with a diameter of 1.0 mm in a vertical sand mill. The sand mill-dispersed solution was then further dispersed for 1 hour in an ultrasonic disperser (UT-205, manufactured by Sharp Corporation) to prepare coating solution 7 for the undercoat layer. The output of the ultrasonic disperser was set to 100%. No media such as glass beads were used in this milling process.

[0075] [Preparation example of coating solution 8 for undercoat layer] Coating Solution 8 for Undercoat Layer was prepared in the same manner as in Preparation Example of Coating Solution 7 for Undercoat Layer, except that the sand mill dispersion treatment time was changed to 4 hours.

[0076] [Preparation example of coating solution 9 for undercoat layer] 100 parts of rutile-type titanium dioxide particles (average primary particle size: 120 nm, manufactured by Teika) were mixed with 500 parts of toluene and stirred, and 1.8 parts of methyldimethoxysilane ("TSL8117" manufactured by Toshiba Silicones) was added and stirred for 8 hours. Thereafter, the toluene was distilled off under reduced pressure, and the mixture was dried at 120°C for 3 hours to obtain rutile-type titanium dioxide particles that had been surface-treated with methyldimethoxysilane. A dispersion was prepared by adding 18 parts of the methyldimethoxysilane-surface-treated rutile-type titanium dioxide particles, 4.5 parts of N-methoxymethylated nylon (product name: Toresin EF-30T, manufactured by Nagase ChemteX), and 1.5 parts of copolymer nylon resin (product name: Amilan CM8000, manufactured by Toray) to a mixed solvent of 90 parts of methanol and 60 parts of 1-butanol. This dispersion was dispersed for 6 hours using glass beads with a diameter of 1.0 mm in a vertical sand mill. The sand mill-dispersed solution was then further dispersed for 1 hour in an ultrasonic disperser (UT-205, manufactured by Sharp) to prepare coating solution 9 for the undercoat layer. The output of the ultrasonic disperser was set to 100%. No media such as glass beads were used in this milling process.

[0077] [Preparation example of coating solution 10 for undercoat layer] In the preparation example of coating solution 1 for undercoat layer, coating solution 10 for undercoat layer was prepared in the same manner as coating solution 1 for undercoat layer, except that methyldimethoxysilane was changed to vinyltrimethoxysilane (product name: KBM-1003, manufactured by Shin-Etsu Chemical Co., Ltd.).

[0078] [Preparation example of coating solution 11 for undercoat layer] Coating Solution 11 for Undercoat Layer was prepared in the same manner as in Preparation Example of Coating Solution 10 for Undercoat Layer, except that the sand mill dispersion treatment time was changed to 4 hours.

[0079] [Preparation example of coating solution 12 for undercoat layer] A dispersion was prepared by adding 18 parts of rutile titanium dioxide particles (average primary particle size: 50 nm, manufactured by Teika), 4.5 parts of N-methoxymethylated nylon (trade name: Toresin EF-30T, manufactured by Nagase ChemteX), and 1.5 parts of copolymer nylon resin (trade name: Amilan CM8000, manufactured by Toray) to a mixed solvent of 90 parts of methanol and 60 parts of 1-butanol. This dispersion was dispersed for 6 hours using a vertical sand mill with 1.0 mm diameter glass beads. The sand milled dispersion was then further dispersed for 1 hour using an ultrasonic disperser (UT-205, manufactured by Sharp) to prepare undercoat layer coating solution 12. The output of the ultrasonic disperser was set to 100%. No media such as glass beads were used in this milling process.

[0080] [Preparation example of coating solution 13 for undercoat layer] A dispersion was prepared by adding 18 parts of rutile titanium dioxide particles (average primary particle size: 120 nm, manufactured by Teika), 4.5 parts of N-methoxymethylated nylon (trade name: Toresin EF-30T, manufactured by Nagase ChemteX), and 1.5 parts of copolymer nylon resin (trade name: Amilan CM8000, manufactured by Toray) to a mixed solvent of 90 parts of methanol and 60 parts of 1-butanol. This dispersion was dispersed for 6 hours in a vertical sand mill using glass beads with a diameter of 1.0 mm. The sand milled dispersion was then further dispersed for 1 hour in an ultrasonic disperser (UT-205, manufactured by Sharp) to prepare coating solution 13 for the undercoat layer. The output of the ultrasonic disperser was set to 100%. No media such as glass beads were used in this milling process.

[0081] [Preparation example of coating solution 14 for undercoat layer] In the preparation example of coating solution 10 for undercoat layer, coating solution 14 for undercoat layer was prepared in the same manner as coating solution 10 for undercoat layer, except that rutile-type titanium oxide particles (average primary particle size: 100 nm, manufactured by Teika) were used.

[0082] [Synthesis of phthalocyanine pigments] [Synthesis Example 1] Under a nitrogen flow atmosphere, 5.46 parts of orthophthalonitrile and 45 parts of α-chloronaphthalene were added to a reaction vessel, which was then heated to 30°C and maintained at that temperature. Next, 3.75 parts of gallium trichloride were added at this temperature (30°C). The water concentration of the mixed solution at the time of addition was 150 ppm. The temperature was then increased to 200°C. Next, under a nitrogen flow atmosphere, the mixture was reacted at 200°C for 4.5 hours, then cooled, and the product was filtered when the temperature reached 150°C. The resulting filtrate was dispersed and washed using N,N-dimethylformamide at 140°C for 2 hours, followed by filtration. The resulting filtrate was washed with methanol and dried, yielding a chlorogallium phthalocyanine pigment in a 71% yield.

[0083] [Synthesis Example 2] 4.65 parts of the chlorogallium phthalocyanine pigment obtained in Synthesis Example 1 was dissolved in 139.5 parts of concentrated sulfuric acid at 10°C, and the solution was added dropwise to 620 parts of ice water with stirring to reprecipitate, followed by vacuum filtration using a filter press. A No. 5C filter (manufactured by Advantec Co., Ltd.) was used. The resulting wet cake (filtrate) was dispersed and washed with 2% aqueous ammonia for 30 minutes, and then filtered using a filter press. The resulting wet cake (filtrate) was then dispersed and washed with ion-exchanged water, and then filtered three times using a filter press. Finally, the solution was freeze-dried to obtain a hydroxygallium phthalocyanine pigment (hydrated hydroxygallium phthalocyanine pigment) with a solids content of 23% in a yield of 97%.

[0084] [Synthesis Example 3] 6.6 kg of the hydroxygallium phthalocyanine pigment obtained in Synthesis Example 2 was dried using a Hyper Dry dryer (trade name: HD-06R, frequency (oscillation frequency): 2455 MHz±15 MHz, manufactured by Nippon Biocon) as follows. The hydroxygallium phthalocyanine pigment was placed on a dedicated circular plastic tray in the form of a lump (a wet cake thickness of 4 cm or less) as it was removed from the filter press, and the far infrared rays were turned off, with the temperature of the inner wall of the dryer set to 50° C. During microwave irradiation, the vacuum pump and leak valve were adjusted to adjust the degree of vacuum to 4.0 to 10.0 kPa. First, in the first step, 4.8 kW microwaves were irradiated onto the hydroxygallium phthalocyanine pigment for 50 minutes. Next, the microwaves were turned off, the leak valve was closed, and a high vacuum of 2 kPa or less was created. At this point, the solids content of the hydroxygallium phthalocyanine pigment was 88%. In the second step, the leak valve was adjusted to adjust the vacuum level (pressure inside the dryer) to within the set value (4.0 to 10.0 kPa). Next, 1.2 kW microwaves were irradiated onto the hydroxygallium phthalocyanine pigment for 5 minutes. Then, the microwaves were turned off, the leak valve was closed, and a high vacuum of 2 kPa or less was created. This second step was repeated once more (twice in total). At this point, the solids content of the hydroxygallium phthalocyanine pigment was 98%. Furthermore, in the third step, microwave irradiation was carried out in the same manner as in the second step, except that the microwave output in the second step was changed from 1.2 kW to 0.8 kW. This third step was repeated once more (twice in total). In the fourth step, the leak valve was adjusted to restore the vacuum (pressure inside the dryer) to the set value (4.0 to 10.0 kPa). The hydroxygallium phthalocyanine pigment was then irradiated with 0.4 kW microwaves for 3 minutes, and the microwaves were then turned off and the leak valve was closed to create a high vacuum of 2 kPa or less. This fourth step was repeated seven more times (for a total of eight times). Over a total of three hours, 1.52 kg of hydroxygallium phthalocyanine pigment (crystals) with a moisture content of 1% or less was obtained.

[0085] [Synthesis Example 4] 5.0 g of o-phthalodinitrile and 2.0 g of titanium tetrachloride were heated and stirred in 100 g of α-chloronaphthalene at 200°C for 3 hours, then cooled to 50°C. The precipitated crystals were filtered off to obtain a dichlorotitanium phthalocyanine paste. This was then washed with stirring in 100 mL of N,N-dimethylformamide heated to 100°C, followed by two repeated washes with 100 mL of methanol at 60°C and then filtered. The resulting paste was then stirred in 100 mL of deionized water at 80°C for 1 hour and filtered to obtain 4.3 g of blue titanyl phthalocyanine pigment. Next, this pigment was dissolved in 30 mL of concentrated sulfuric acid and added dropwise to 300 mL of deionized water at 20°C while stirring to reprecipitate, which was then filtered and thoroughly washed with water to obtain an amorphous titanyl phthalocyanine pigment. 4.0 g of this amorphous titanyl phthalocyanine pigment was suspended and stirred in 100 mL of methanol at room temperature (22°C) for 8 hours, filtered, and dried under reduced pressure to obtain a low-crystalline titanyl phthalocyanine pigment.

[0086] [Synthesis Example 5] Under a nitrogen flow atmosphere, 10 g of gallium trichloride and 29.1 g of orthophthalonitrile were added to 100 mL of α-chloronaphthalene and reacted at 200°C for 24 hours, after which the product was filtered. The resulting wet cake was heated and stirred in N,N-dimethylformamide at 150°C for 30 minutes, and then filtered. The filtered product was washed with methanol and dried to obtain a chlorogallium phthalocyanine pigment in an 83% yield. Two parts of the chlorogallium phthalocyanine pigment obtained by the above method were dissolved in 50 parts of concentrated sulfuric acid, stirred for 2 hours, and then added dropwise to an ice-cooled mixed solution of 170 mL of distilled water and 66 mL of concentrated aqueous ammonia to reprecipitate the pigment, which was thoroughly washed with distilled water and dried to obtain 1.8 parts of a hydroxygallium phthalocyanine pigment.

[0087] [Preparation example of coating liquid 1 for charge generating layer] One part of the hydroxygallium phthalocyanine pigment obtained in Synthesis Example 3, 9 parts of N-methylformamide (product code: F0059, manufactured by Tokyo Chemical Industry Co., Ltd.), and 15 parts of glass beads with a diameter of 0.9 mm were milled for 70 hours at a cooling water temperature of 18°C ​​using a sand mill (K-800, manufactured by Igarashi Machinery Manufacturing Co., Ltd. (now Imex), disk diameter 70 mm, number of disks: 5). This milling was carried out at a disk rotation rate of 400 revolutions per minute. After adding 30 parts of N-methylformamide to the resulting solution, the mixture was filtered, and the residue on the filter was thoroughly washed with tetrahydrofuran. The washed residue was then vacuum dried to obtain 0.45 parts of hydroxygallium phthalocyanine pigment. In the X-ray diffraction spectrum using CuKα radiation, the obtained pigment exhibits peaks at Bragg angles 2θ of 7.5°±0.2°, 9.9°±0.2°, 16.2°±0.2°, 18.6°±0.2°, 25.2°±0.2°, and 28.3°±0.2°. The crystal correlation length estimated from the peak at 7.5°±0.2°, which is the most intense diffraction peak in the range of 5° to 35°, was r=27 [nm]. 1 The content of the amide compound (N-methylformamide) represented by the above formula (A1) in the hydroxygallium phthalocyanine crystal particles estimated by H-NMR measurement was 1.5 mass % relative to the content of hydroxygallium phthalocyanine. Next, 25 parts of the hydroxygallium phthalocyanine pigment obtained by milling, 5 parts of polyvinyl butyral (product name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.), and 190 parts of cyclohexanone were placed in a centrifuge container and centrifuged for 30 minutes at a set temperature of 18°C ​​using a high-speed refrigerated centrifuge (product name: Himac CR22G, manufactured by Hitachi Koki Co., Ltd.). A rotor (product name: R14A, manufactured by Hitachi Koki Co., Ltd.) was used, and acceleration and deceleration were performed at the shortest possible speed, 1,800 revolutions per minute. The supernatant liquid after this centrifugation was quickly collected in another centrifuge container. The solution obtained in this way was centrifuged again in the same manner as above, except that the speed was changed to 8,000 revolutions per minute. The supernatant liquid after centrifugation was removed and the remaining solution was quickly collected in another sample bottle. The weight ratio of the hydroxygallium phthalocyanine pigment to polyvinyl butyral in the solution obtained in this way was 1 The solid content of the obtained solution was determined by measuring the weight difference before and after drying after drying for 30 minutes in a dryer set at 150°C. Next, polyvinyl butyral (product name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.) and cyclohexanone were added to the solution obtained by the centrifugation process so that the weight ratio of hydroxygallium phthalocyanine pigment, polyvinyl butyral, and cyclohexanone was 20:10:190. 220 parts of this solution and 482 parts of 0.9 mm diameter glass beads were dispersed using a sand mill (K-800, manufactured by Igarashi Machine Manufacturing Co., Ltd. (now Imex), disk diameter 70 mm, number of disks: 5) at a cooling water temperature of 18°C ​​for 4 hours. The disks were rotated at 1,800 revolutions per minute. 444 parts of cyclohexanone and 634 parts of ethyl acetate were added to this dispersion to prepare Coating Solution 1 for the CGL.

[0088] The phthalocyanine pigment of the present invention was evaluated by small-angle X-ray scattering measurement according to the following procedure. Cyclohexanone was added to the prepared coating liquid 1 for charge generating layer to dilute it until the concentration of the charge generating material became 1% by weight, and a measurement sample was prepared. The values ​​were determined by small-angle X-ray scattering measurement (X-ray wavelength: 0.154 nm) using a multipurpose X-ray diffractometer SmartLab manufactured by Rigaku. The scattering profile obtained by the measurement was analyzed using the particle size analysis software NANO-Solver to obtain the particle size distribution, assuming that the particle shape was spherical. As a result of measurement, the crystallite size distribution of the obtained pigment measured by small angle X-ray scattering had a peak at 38 nm, and the half width of the peak was 38 nm.

[0089] [Preparation example of coating liquid 2 for charge generating layer] The pigment was prepared in the same manner as in Charge Generation Layer Coating Liquid 1. The crystallite size distribution of the resulting pigment measured by small angle X-ray scattering had a peak at 30 nm, and the half width of the peak was 40 nm.

[0090] [Preparation example of coating liquid 3 for charge generating layer] The pigment was prepared in the same manner as in Charge Generation Layer Coating Liquid 1. The crystallite size distribution of the resulting pigment measured by small angle X-ray scattering had a peak at 42 nm, and the half-value width of the peak was 50 nm.

[0091] [Preparation example of coating liquid 4 for charge generating layer] The pigment was prepared in the same manner as in Charge Generation Layer Coating Liquid 1. The crystallite size distribution of the resulting pigment measured by small angle X-ray scattering had a peak at 48 nm, and the half width of the peak was 46 nm.

[0092] [Preparation Example of Coating Solution 10 for Charge Generating Layer] 0.5 parts of the titanyl phthalocyanine pigment obtained in Synthesis Example 4, 10 parts of tetrahydrofuran, and 15 parts of glass beads with a diameter of 0.9 mm were milled for 48 hours using a sand mill (K-800, manufactured by Igarashi Machine Manufacturing Co., Ltd. (now Imex), disk diameter 70 mm, number of disks: 5) at a cooling water temperature of 18°C. The milling was performed at 500 disk revolutions per minute. The resulting solution was filtered through a filter (product number: N-NO.125T, pore size: 133 μm, manufactured by NBC Meshtec) to remove the glass beads. 30 parts of tetrahydrofuran were added to the solution, followed by filtration. The filtered product was thoroughly washed with methanol and water. The washed product was then vacuum dried to obtain 0.46 parts of titanyl phthalocyanine pigment. The resulting pigment exhibited a peak at a Bragg angle 2θ of 27.2°±0.2° in its X-ray diffraction spectrum using CuKα radiation. Next, 20 parts of the titanyl phthalocyanine pigment obtained by the milling process, 10 parts of polyvinyl butyral (product name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.), 139 parts of cyclohexanone, and 354 parts of 0.9 mm diameter glass beads were dispersed using a sand mill (K-800, manufactured by Igarashi Machine Manufacturing Co., Ltd. (now Imex), disk diameter 70 mm, number of disks: 5) at a cooling water temperature of 18°C ​​for 4 hours. The disks were rotated at 1,800 revolutions per minute. To this dispersion, 326 parts of cyclohexanone and 465 parts of ethyl acetate were added to prepare Coating Solution 10 for the CGL. The crystallite size distribution of the resulting pigment measured using small-angle X-ray scattering showed a peak at 70 nm with a half-width of 90 nm.

[0093] [Preparation Example of Coating Solution 11 for Charge Generating Layer] 15 parts of titanyl phthalocyanine pigment (CG-01H, manufactured by ITchem), 10 parts of polyvinyl butyral (product name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.), 139 parts of cyclohexanone, and 354 parts of 0.9 mm diameter glass beads were dispersed in a sand mill (K-800, manufactured by Igarashi Machine Manufacturing Co., Ltd. (now Imex), 70 mm diameter, 5 disks) at a cooling water temperature of 18°C ​​for 4 hours. The dispersion was run at 1,800 revolutions per minute. 326 parts of cyclohexanone and 465 parts of ethyl acetate were added to this dispersion to prepare Coating Solution 10 for the CGL. The crystallite size distribution of the resulting pigment measured by small-angle X-ray scattering showed a peak at 160 nm with a half-width of 200 nm.

[0094] [Preparation Example of Coating Solution 12 for Charge Generating Layer] The pigment was prepared in the same manner as in Charge Generation Layer Coating Liquid 1. The crystallite size distribution of the resulting pigment measured by small angle X-ray scattering had a peak at 60 nm, and the half width of the peak was 80 nm.

[0095] [Preparation example of coating liquid 13 for charge generating layer] The pigment was prepared in the same manner as in Charge Generation Layer Coating Liquid 1. The crystallite size distribution of the resulting pigment measured by small angle X-ray scattering had a peak at 145 nm, and the half-value width of the peak was 98 nm.

[0096] [Photoreceptor manufacturing example 1] <Support> An aluminum cylinder having a diameter of 30 mm and a length of 260.5 mm was used as the support (cylindrical support).

[0097] <Conductive layer> A titanium niobium sulfate solution containing 33.7 parts titanium (calculated as TiO2) and 2.9 parts niobium (calculated as Nb2O5) was prepared using anatase titanium dioxide (TiO2) as the substrate. 100 parts of the substrate were dispersed in pure water to prepare a 1000-part suspension, which was then heated to 60°C. The titanium niobium sulfate solution and 10 mol / L sodium hydroxide were added dropwise over 3 hours to adjust the pH of the suspension to 2-3. After the entire amount was added, the pH was adjusted to near neutral, and a polyacrylamide-based flocculant was added to allow the solids to settle. The supernatant was removed, filtered, washed, and dried at 110°C to obtain an intermediate containing 0.1 wt% of organic matter derived from the flocculant (calculated as C). This intermediate was calcined in nitrogen at 750°C for 1 hour, followed by calcination in air at 450°C to produce titanium oxide particles. The obtained particles had an average particle size (average primary particle size) of 220 nm as determined by the particle size measurement method using a scanning electron microscope described above. Next, a phenolic resin (phenolic resin monomer / oligomer) (trade name: Plyofen J-325, manufactured by DIC, resin solid content: 60%, density after curing: 1.3 g / cm) was used as a binder. 2 50 parts of the hydroxybenzoate was dissolved in 35 parts of 1-methoxy-2-propanol as a solvent to obtain a solution. To this solution, 60 parts of titanium oxide particles 1 were added, and the mixture was placed in a vertical sand mill using 120 parts of glass beads with an average particle size of 1.0 mm as a dispersion medium. The mixture was dispersed for 4 hours at a dispersion temperature of 23±3°C and a rotation speed of 1500 rpm (circumferential speed of 5.5 m / s), yielding a dispersion. The glass beads were removed from the dispersion using a mesh. After removing the glass beads, the dispersion was mixed with 0.01 parts of silicone oil (trade name: SH28 PAINT ADDITIVE, manufactured by Toray Dow Corning) as a leveling agent and silicone resin particles (trade name: KMP-590, manufactured by Shin-Etsu Chemical Co., Ltd., average particle size: 2 μm, density: 1.3 g / cm) as a surface roughness imparting agent. 3 8 parts of the above-mentioned acrylic acid ester was added and stirred, and the mixture was filtered under pressure using PTFE filter paper (trade name: PF060, manufactured by Advantec Toyo Co., Ltd.) to prepare a coating liquid for the conductive layer. The conductive layer coating solution thus prepared was dip-coated onto the above-mentioned support to form a coating film, and the coating film was heated at 150°C for 20 minutes to harden, thereby forming a conductive layer with a film thickness of 17 µm.

[0098] <Undercoat layer> The undercoat layer coating solution prepared in accordance with Preparation Example for Undercoat Layer Coating Solution 1 was dip-coated onto the conductive layer to form a coating film, which was then dried by heating at 100° C. for 10 minutes to form an undercoat layer with a thickness of 2 μm. The arithmetic mean roughness Ra, the average length of the roughness curve element Rsm, and Ra / Rsm of the obtained undercoat layer according to JIS B0601:2001 are shown in Table 1.

[0099] The surface roughness of the undercoat layer in the present invention was evaluated according to the following procedure. The prepared photoreceptor drum charge transport layer was dissolved in toluene and dried to expose the surface of the charge generation layer. Next, the exposed photoreceptor drum charge generation layer was dissolved in cyclohexanone and dried to expose the surface of the undercoat layer. The photoreceptor with the exposed undercoat layer surface was then cut into a square with sides of approximately 5 mm to serve as a measurement sample. A JEOL JSPM-5200 scanning probe microscope was used to obtain height information over a 500 nm square area on the surface of the undercoat layer. A NanoWorld NCR cantilever was used to measure the height information by scanning the surface in tapping mode. From the obtained height information, the arithmetic mean roughness Ra, as well as the mean length Rsm and Ra / Rsm of the roughness curve elements according to JIS B0601:2001 were calculated.

[0100] <Charge generation layer> The coating liquid for the charge generation layer prepared in accordance with Preparation Example for Coating Liquid 1 for the charge generation layer was dip-coated onto the above-mentioned undercoat layer to form a coating film, and the coating film was dried by heating at a temperature of 100°C for 10 minutes to form a charge generation layer with a film thickness of 0.2 μm.

[0101] <Charge transport layer> 5 parts of a triarylamine compound represented by the following formula as a charge transport material: [ka] 5 parts of a triarylamine compound represented by the following formula: [ka] A coating solution for the charge transport layer was prepared by dissolving 10 parts of polycarbonate (trade name: Iupilon Z-400, manufactured by Mitsubishi Engineering Plastics) in a mixed solvent of 25 parts of orthoxylene, 25 parts of methyl benzoate, and 25 parts of dimethoxymethane. The charge transport layer coating liquid thus prepared was dip-coated onto the charge generation layer to form a coating film, and the coating film was dried by heating at a temperature of 120°C for 30 minutes to form a charge transport layer with a thickness of 17 μm.

[0102] [Photoreceptor manufacturing examples 2-21] An electrophotographic photoreceptor was produced in the same manner as in Photoreceptor Production Example 1, except that the undercoat layer coating liquid, undercoat layer thickness, charge generation layer coating liquid, and charge generation layer thickness were changed as shown in Table 1. The arithmetic mean roughness Ra, as measured in JIS B0601:2001, and the average length Rsm and Ra / Rsm of the roughness curve element of the obtained undercoat layer are shown in Table 1. In the table, "HOGaPc" means "hydroxygallium phthalocyanine pigment" and "TiOPc" means "titanyl phthalocyanine pigment."

[0103] [Comparative manufacturing example] <Support> A machined aluminum cylinder having a diameter of 30 mm and a length of 260.5 mm was used as a support (cylindrical support).

[0104] <Undercoat layer> The coating solution for undercoat layer prepared in accordance with Preparation Example for Coating Solution 13 for Undercoat Layer was dip-coated onto the same conductive layer as in Photoreceptor Production Example 1 to form a coating film, and the coating film was dried by heating at a temperature of 100°C for 10 minutes to form an undercoat layer with a thickness of 3.7 μm.

[0105] <Charge generation layer> The coating liquid for the charge generation layer prepared according to Preparation Example 11 of Coating Liquid for Charge Generation Layer was dip-coated onto the above-mentioned undercoat layer to form a coating film, and the coating film was heated and dried at a temperature of 100°C for 10 minutes to form a charge generation layer with a film thickness of 0.2 μm.

[0106] <Charge transport layer> 23 parts of a triarylamine compound represented by the following formula as a charge transport material: [ka] 23 parts of a triarylamine compound represented by the following formula: [ka] 15 parts of an arylamine compound represented by the following formula: [ka] 5 parts of a phenolic compound represented by the formula: [ka] 8 parts of a phenolic compound represented by the formula: [ka] A coating solution for the charge transport layer was prepared by dissolving 10 parts of polycarbonate (trade name: Iupilon Z-400, manufactured by Mitsubishi Engineering Plastics) in a mixed solvent of 25 parts of orthoxylene, 25 parts of methyl benzoate, and 25 parts of dimethoxymethane. The charge transport layer coating liquid thus prepared was dip-coated onto the charge generation layer to form a coating film, and the coating film was dried by heating at a temperature of 120°C for 30 minutes to form a charge transport layer with a thickness of 17 μm.

[0107] [Table 1]

[0108] [Evaluation of Electrophotographic Photoconductor] The following evaluations (Examples 1 to 7 and Comparative Examples) were performed on the above-described photoconductor production examples. The results are shown in Table 2.

[0109] [Evaluation of Electrophotographic Photoconductor] [Evaluation of R, S2, and S3] For the evaluation of R, S2, and S3, a photoconductor testing apparatus (trade name: CYNTHIA59, manufactured by Gentec Co., Ltd.) was used. The evaluation was carried out after leaving the photoconductors of the examples and comparative examples in the photoconductor testing apparatus at an environment of a temperature of 23.5°C and a relative humidity of 50% RH for 24 hours or more. Also, a conductive rubber roller with a diameter of 8 mm was used as the charging member. In the measurement of the potential, a surface potential probe (model 6000B-8: manufactured by Trek Japan Co., Ltd.) was installed at a position 1 mm away from the electrophotographic photoconductor, and a surface potentiometer (model 344: manufactured by Trek Japan Co., Ltd.) was used. Under the above conditions, R, S2, and S3 were calculated and evaluated from Formula (E1), Formula (E2), and Formula (E3) according to the above-described procedure. FIG. 7 is a graph regarding the photoconductor obtained in Photoconductor Production Example 1, with the vertical axis being V exp and the horizontal axis being I exp ; FIG. 8 is a graph regarding the photoconductor obtained in Photoconductor Production Example 1, with the vertical axis being y and the horizontal axis being x; FIG. 10 is a graph regarding the photoconductor obtained in Photoconductor Production Example 1, with the vertical axis being R and the horizontal axis being x.

[0110] [Evaluation of Exposure Part Potential Control] The electrophotographic apparatus used for evaluation was a modified Hewlett-Packard laser beam printer (product name: HP Color LaserJet Enterprise M652). The modifications included adjustment of the voltage applied to the charging roller, adjustment of the image exposure light amount, and modification to enable the detection of the charge transfer amount and the control of the image-exposed area potential, as described below. The charge transfer amount per unit time was detected by charging the electrophotographic photosensitive member using a charging means, and image exposure was performed using the image exposure means with at least one light exposure point at a light amount weaker than the light amount that indicates the minimum value of the normalized radius of curvature R, as expressed by the above-mentioned formula (E1), and then with at least two light exposure points at a light amount stronger than the minimum value of the normalized radius of curvature, thereby forming a latent image on the photosensitive member as shown in Figures 3 and 4. That is, at least three points of image exposure with different light intensity (the number of points can be controlled arbitrarily), three electrostatic latent image patterns are formed (according to the number of image exposure points), and then the exposed area is charged by a charging means, and the current flowing through the exposed area and the amount of charge transfer per unit time are measured using the current detection function of the high-voltage piezoelectric element (means for detecting the amount of charge transfer).The image exposure potential control was performed by graphing the detection results as shown in Figure 5 and finding the light intensity at the intersection to determine the image exposure amount and control the potential of the exposed area. The surface potential of the photoreceptor was measured by modifying the cartridge and attaching a potential probe (trade name: model 6000B-8, manufactured by Trek Japan Co., Ltd.) to the development position. The potential was measured using a surface potentiometer (trade name: model 344, manufactured by Trek Japan Co., Ltd.). Under the above conditions, the detected light amount and the error between the detected light amount at three and six image exposure points and the actual light amount when R was at its minimum value were evaluated.

[0111] [Table 2]

[0112] [Table 3]

[0113] It was found that by increasing the number of measurement points from 3-point image exposure measurement to 6-point measurement, the detection time increases, but the error decreases. It was also found that the error decreases when R becomes smaller than 0.24. Furthermore, as in the comparative example, it was found that the error increases when R becomes larger than 0.24. [Explanation of symbols]

[0114] 101: Conductive substrate 102: Undercoat layer 103: Charge generating layer 104: Hole transport layer 105: Photosensitive layer 1: Electrophotographic photoreceptor 2: Axis 3: Charging means 4: Image exposure light 5: Developing method 6: Transfer means 7: Transfer material 8: Image fixing means 9: Cleaning means 10: Pre-exposure light 11: Process cartridge 12: Guidance means 13: High voltage power supply

Claims

1. an electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member, image exposure means for irradiating the surface of the electrophotographic photosensitive member with image exposure light to form an electrostatic latent image on the surface of the electrophotographic photosensitive member, developing means for developing the electrostatic latent image with toner to form a toner image on the surface of the electrophotographic photosensitive member, transfer means for transferring the toner image from the surface of the electrophotographic photosensitive member to a transfer material, charge transfer amount detection means for detecting the amount of charge transfer per unit time due to discharge to the electrophotographic photosensitive member, and an electrophotographic apparatus comprising: a true photosensitive member is charged; said image exposure means imagewise exposes said electrophotographic photosensitive member with at least one light amount weaker than the light amount showing the minimum value of a normalized radius of curvature R of said electrophotographic photosensitive member, said normalized radius of curvature R being expressed by the following formula (E1), and at least two light amounts stronger than the light amount showing the minimum value of said normalized radius of curvature R; said charge transfer amount detection means detects an amount of charge transferred to said electrophotographic photosensitive member per unit time when an exposed portion is charged; and said electrophotographic apparatus comprises an exposed portion potential control means for controlling a potential of said exposed portion of said electrophotographic photosensitive member based on a result of said detection; The electrophotographic photoreceptor is At a temperature of 23.5°C and a relative humidity of 50% RH, (1) The surface potential of the electrophotographic photosensitive member is set to 0 [V], (2) charging the electrophotographic photosensitive member for 0.005 seconds so that the absolute value of the initial surface potential of the electrophotographic photosensitive member becomes 500 [V]; (3) 0.02 seconds after the start of charging, the wavelength is 805 [nm] and the intensity is 25 [mW / cm ２ ] light for t seconds continuously. ｅｘｐ [μJ / cm ２ ] light, (4) The absolute value of the surface potential of the electrophotographic photosensitive member after exposure, measured 0.06 seconds after the start of charging, is V ｅｘｐ When [V] is used, Measurements (1) to (4) are performed by changing t. ｅｘｐ to 0.000 [μJ / cm ２ ] to 1.000 [μJ / cm ２ ] up to 0.001 [μJ / cm ２ ] and the horizontal axis is I ｅｘｐ The vertical axis is V ｅｘｐ In a graph where V of the graph ｅｘｐ When the light intensity becomes I = 250 [V], １／２ [μJ / cm ２ ], then 10.I １／２ The horizontal axis I ｅｘｐ The normalized light amount obtained by normalizing the above is set to x, and the vertical axis V is set so that the value 500 [V] on the vertical axis of the graph is 1 and the value when x = 1 is 0. ｅｘｐ When the normalized surface potential obtained by normalizing is y, In a graph with the horizontal axis x and the vertical axis y, the minimum value of the normalized radius of curvature R calculated by the following formula (E1) is 0.24 or less. Electrophotographic apparatus characterized by: [Equation 1]

2. 2. The electrophotographic apparatus according to claim 1, wherein the minimum value of the normalized radius of curvature R is 0.21 or less.

3. When the normalized surface potential y of the graph becomes 0.5, the normalized light amount x is expressed as Is ０．５ [μJ / cm ２ ], light intensity Is ０．５ 4 times the light intensity of 4Is ０．５ [μJ / cm ２ ], and 5 times the light intensity of 5Is ０．５ [μJ / cm ２ ], and x = 4Is ０．５ When y is y4, x = 5Is ０．５ When y is y5, The slopes S2 and S3 calculated by the following formulas (E2) and (E3) satisfy S2≧3.0 and S3≦0.

41.

2. The electrophotographic apparatus according to claim 1. [Equation 2] [Equation 3]

4. 4. The electrophotographic apparatus according to claim 3, wherein the slope S3 is 0.21 or less.

5. 4. The electrophotographic apparatus according to claim 3, wherein the slope S3 is 0.15 or less.

6. 6. The electrophotographic apparatus according to claim 1, wherein the exposed portion potential control means performs image exposure by the image exposure means with a light amount at least n points (n is an integer of 2 or more) weaker than the light amount that shows the minimum value of the normalized radius of curvature R of the electrophotographic photosensitive member, and a light amount at least m points (m is an integer of 3 or more) stronger than the light amount that shows the minimum value of the normalized radius of curvature R of the electrophotographic photosensitive member, detects an amount of charge transfer per unit time to the electrophotographic photosensitive member when the exposed portion is charged, and controls the exposed portion potential of the electrophotographic photosensitive member based on the detection result.

7. 7. The electrophotographic apparatus according to claim 1, wherein the electrophotographic photoreceptor has, in this order, a support, an undercoat layer, a charge generating layer, and a charge transport layer containing a charge transport material, and the undercoat layer contains a polyamide resin and metal oxide particles.

8. 8. The electrophotographic apparatus according to claim 7, wherein the metal oxide particles are titanium oxide particles, and the titanium oxide particles have an average primary particle size of 10 nm or more and 100 nm or less.

9. 9. The electrophotographic apparatus according to claim 7, wherein the thickness of the undercoat layer is 0.5 [mu]m or more and 3.0 [mu]m or less.

10. 10. The electrophotographic device according to claim 7, wherein the charge generation material of the charge generation layer contains a titanyl phthalocyanine pigment, and the titanyl phthalocyanine pigment has crystal particles of a crystalline type that exhibits peaks at Bragg angles 2θ of 9.8°±0.3° and 27.1°±0.3° in an X-ray diffraction spectrum using CuKα rays, and has a peak in a crystal particle size distribution measured by small-angle X-ray scattering of 50 nm to 150 nm, with the half-value width of the peak being 100 nm or less.

11. 10. The electrophotographic device according to claim 7, wherein the charge generation material of the charge generation layer contains a hydroxygallium phthalocyanine pigment, and the hydroxygallium phthalocyanine pigment has crystal particles of a crystalline type that exhibit peaks at Bragg angles 2θ of 7.4°±0.3° and 28.2°±0.3° in an X-ray diffraction spectrum using CuKα rays, and has a peak in a crystal particle size distribution measured by small-angle X-ray scattering of 30 nm to 50 nm, with the half-value width of the peak being 50 nm or less.

12. 12. The electrophotographic apparatus according to claim 7, wherein the charge generating layer has a thickness of 0.16 μm or more.

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