electrophotographic device

Abstract

To solve the problem in which: in using an LED array in an electrophotographic device as exposure means, when the quantity of light in a high light quantity area is used for image formation, electric charges remaining in a photoreceptor causes a ghost image, and when latent image design is performed in a low light quantity area, image unevenness due to variations in light quantity occurs.SOLUTION: In order to solve the problem, an electrophotographic device is provided that has a minimum value of the normalized radius of curvature R in a normalization graph of the E-V curve of 0.24 or less, and when the light quantity when the normalized radius of curvature R becomes the minimum value is defined as Emin [μJ / cm2], performs exposure at a light quantity with which the average light quantity of a light-emitting diode array satisfies 0.8×Emin or more and 1.1×Emin or less.SELECTED DRAWING: Figure 5

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 can produce higher image quality, and there is a demand for apparatuses that can output image data with high stability in external environments such as temperature and humidity, as well as during repeated use.

[0003] In electrophotographic devices using electrophotographic photoreceptors (also called photoconductors), such as copiers, laser beam printers, and facsimiles, an electrostatic latent image is formed on a uniformly charged 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.

[0004] In order to achieve high-quality image formation, an LED array, which is a collection of laser diode (hereinafter referred to as "diode" or "LED") elements, is sometimes used as an image exposure means. When using an LED array, variations in the amount of light emitted by the image exposure can occur due to individual differences in the LED elements. As a result, in the process from charging to image exposure, unevenness occurs in the electrostatic latent image formed on the surface of the electrophotographic photoreceptor (electrostatic latent image unevenness), which is known to result in uneven image density and uneven dot image (uneven size and shape of each formed dot).

[0005] Patent Document 1 proposes the following method for improving the surface potential unevenness of a photoconductor caused by the uneven light intensity due to individual differences in LED elements, and the uneven dot image caused by the uneven surface potential. Specifically, it proposes a method for reducing image unevenness caused by variations in the light intensity of an LED array by forming an image using the exposure amount in the residual potential region of the photoconductor's light attenuation curve. The light attenuation curve is a curve obtained by measuring the exposed area potential while gradually changing the light intensity from the charging potential Vd. It is also called the EV curve or the relationship between exposure amount and surface potential. The residual potential region refers to the region of the light attenuation curve where the amount of change in the exposed area potential does not change significantly even when the exposure amount is increased.

[0006] However, when an image is formed with an exposure amount in the residual potential region, residual charges are generated in the photosensitive member, which poses a problem of the likelihood of ghost images occurring.

[0007] Furthermore, as in Patent Document 2, there is a proposal to use the amount of light in the linear region on the low light intensity side of the light attenuation curve in the EV curve mentioned above in order to suppress ghost images. However, simply reducing the amount of light during image formation makes it difficult to reduce image unevenness caused by the light intensity fluctuation of the LED array mentioned above.

[0008] That is, with the conventional method using a photosensitive member, it is difficult to improve both the unevenness of the dot image produced by the LED array and the occurrence of ghost images. [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-315005 [Patent Document 2] Japanese Patent Application Laid-Open No. 2001-125300 Summary of the Invention [Problem to be solved by the invention]

[0010] As mentioned above, when an LED array is used as an exposure means in an electrophotographic device, the amount of light used is often in the residual potential region (the region where the change in the bright area potential is small relative to the change in the amount of exposure) in the light attenuation curve of the electrophotographic photosensitive member in order to reduce unevenness in the bright area potential caused by variations in the amount of light due to individual differences between LED elements, i.e., image unevenness (Patent Document 1). However, when the residual potential region in the light attenuation curve, i.e., the light amount in the high light intensity region, is used for image formation, the charge remaining in the photosensitive member can cause a significant change in the light attenuation characteristics, such as a decrease in charging ability, in the next process and thereafter, resulting in the problem of the generation of unintended images, i.e., ghost images.

[0011] Conversely, if a latent image is designed in a low light area to reduce the occurrence of ghost images (Patent Document 2), as mentioned above, image unevenness occurs due to variations in light intensity caused by individual differences between LED elements.

[0012] An object of the present invention is to provide an electrophotographic apparatus that uses an LED array as an exposure means, and that utilizes an electrophotographic photosensitive member that exhibits a characteristic light attenuation curve, i.e., that has a small minimum value of curvature of the light attenuation curve, and that is capable of forming an image by forming a potential at the exposed portion of the photosensitive member using a light amount close to the exposure amount that exhibits the minimum curvature. [Means for solving the problem]

[0013] The above object can be achieved by the present invention as follows. That is, the electrophotographic apparatus according to the present invention is an electrophotographic photoreceptor that carries a toner image for forming an image on a recording material; a charging means for charging the electrophotographic photosensitive member; an exposure means for exposing the surface of the charged electrophotographic photosensitive member to light; An electrophotographic apparatus , The exposure means is a light emitting diode array composed of a plurality of light emitting diode elements. the law of nature , At a temperature of 23.5°C and a relative humidity of 50% RH, the electrophotographic photoreceptor (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 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 light intensity is I exp [μJ / cm 2 the electrophotographic photosensitive member after charging is exposed to light of (4) The absolute value of the surface potential of the electrophotographic photosensitive member measured 0.06 seconds after the start of charging is V exp [V], The operations and measurements from (1) to (4) are performed by 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 The graph where V of the graph exp = 250[V], the amount of light when 1 / 2 [μJ / cm 2 ] and I exp =10 I 1 / 2 [μJ / cm 2 ] at x=1, I exp = 0 [μJ / cm 2 ] with x=0, V exp =500[V] to y=1, V exp =(I exp is 10.I 1 / 2 [μJ / cm 2 ] when V exp [V]) with y=0, When normalized as a normalized graph with the horizontal axis x and the vertical axis y, In the normalized graph, the minimum value of the normalized radius of curvature R calculated by the following formula (E1) is 0.21 is as follows: I corresponding to x where the normalized radius of curvature R is the minimum value exp Emin [μJ / cm 2 ], The light-emitting diode array has an average light quantity of 0.9×Emin or more in the exposure means. 1.0 The electrophotographic apparatus is characterized in that it exposes with a light amount that satisfies the condition of .times.Emin or less.

number

[0014] According to the present invention, it is possible to provide an electrophotographic apparatus using an LED array in which both one-dot image unevenness due to light quantity fluctuations for each element of the LED array and the occurrence of ghost images are improved. [Brief explanation of the drawings]

[0015] [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] This is a typical example of a graph showing measured Vexp and Iexp for a certain photoreceptor. [Figure 4] This is a normalized version of the graph in Figure 3 (normalized graph). [Figure 5] FIG. 5 is a diagram showing the normalized radius of curvature for the normalized graph of FIG. 4. [Figure 6] FIG. 10 is a diagram showing the relationship between the amount of light and the normalized radius of curvature for a certain photosensitive member. [Figure 7] FIG. 1 shows an input image (a) used in ghost image evaluation and a typical output image (b). DETAILED DESCRIPTION OF THE INVENTION

[0016] 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 photoreceptor that carries a toner image for forming an image on a recording material; a charging means for charging the electrophotographic photosensitive member; an exposure means for exposing the surface of the charged electrophotographic photosensitive member to light; An electrophotographic apparatus , The exposure means is a light emitting diode array composed of a plurality of light emitting diode elements. the law of nature , At a temperature of 23.5°C and a relative humidity of 50% RH, the electrophotographic photoreceptor (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 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 light intensity is I exp [μJ / cm 2 the electrophotographic photosensitive member after charging is exposed to light of (4) The absolute value of the surface potential of the electrophotographic photosensitive member measured 0.06 seconds after the start of charging is V exp [V], The operations and measurements from (1) to (4) are performed by 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 The graph where V of the graph exp = 250[V], the amount of light when 1 / 2 [μJ / cm 2 ] and I exp =10 I 1 / 2 [μJ / cm 2 ] at x=1, I exp = 0 [μJ / cm 2 ] with x=0, V exp =500[V] to y=1, V exp =(I exp is 10.I 1 / 2 [μJ / cm 2 ] when Vexp [V]) with y=0, When normalized as a normalized graph with the horizontal axis x and the vertical axis y, In the normalized graph, the minimum value of the normalized radius of curvature R calculated by the following formula (E1) is 0.21 is as follows: I corresponding to x where the normalized radius of curvature R is the minimum value exp Emin [μJ / cm 2 ], The light emitting diode array is Can The average light intensity 0.9 ×Emin or above 1.0 The electrophotographic apparatus is characterized in that it exposes with a light amount that satisfies the condition of .times.Emin or less.

number

[0017] The light-emitting diode array (LED array) used in the present invention has a structure in which multiple chip-shaped light-emitting diode elements (LED elements) are arranged in a row along the axial direction of the electrophotographic photosensitive member, and the LED array may be further configured by arranging multiple rows in series or parallel. The LED elements (also called light-emitting points or light-emitting elements) may be arranged two-dimensionally, for example, in a staggered pattern. The LED array is controlled by a drive circuit to illuminate and emit a light beam in accordance with image data.

[0018] It is preferable for the LED array to have a relatively small spot diameter of light from the LED elements irradiating the photoreceptor surface, and the size of the LED elements constituting the LED array is preferably in the range of 20 μm to 100 μm, more preferably 40 μm to 80 μm. If it is smaller than 20 μm, the light intensity fluctuation between LED elements, which is a problem cited in this application, is likely to become large, easily causing uneven image density. Conversely, if it is larger than 100 μm, adjacent LED spots will interfere with each other during irradiation, making it difficult to form an image.

[0019] The preferred range of wavelength of light electrically emitted by the LED elements constituting the LED array depends on the charge-generating material contained in the photoreceptor (described later), but is 400 nm to 900 nm. The number and arrangement of the LED elements constituting the LED array are not particularly limited as long as the desired resolution and light exposure amount are achieved, but a preferred configuration is, for example, 256 light-emitting diode elements arranged in series and parallel at a density of 1600 dpi (dots per inch).

[0020] In the present invention, the amount of light that the LED array irradiates to form an electrostatic latent image on an electrophotographic photosensitive member refers to the average value of the light amount of the LED array. That is, in the present invention, the light amount used during the above-mentioned image formation is selected within a predetermined range, and the light amount at this time refers to the averaged light amount. The averaged light amount of the LED array is determined as follows. That is, in the present invention, the average light amount of the LED array is defined as the value of the light amount calculated by sliding a light amount measuring tool in 5 mm increments along the longitudinal axis of the photosensitive member in an electrophotographic device equipped with the LED array and a photosensitive member, measuring the light amount at 5 mm intervals from the top 5 mm position to the bottom 5 mm position of the photosensitive member, and averaging the measured values.

[0021] In the present invention, an electrostatic latent image is formed on an electrophotographic photosensitive member by an LED array, and a toner image is formed by developing the electrostatic latent image with toner, but it is essential to use an electrophotographic photosensitive member that can set the amount of light irradiated onto the electrophotographic photosensitive member from the LED array during electrostatic latent image formation so as to fall within the following range: That is, when the amount of light Emin is the amount of light at which the normalized radius of curvature expressed by the above formula (E1) has a minimum value in a graph normalized by x on the horizontal axis and y on the vertical axis of the EV curve of the photosensitive member, it is necessary to form an image by exposing the photosensitive member to an amount of light that satisfies 0.8 × Emin or more and 1.1 × Emin or less.

[0022] Generally, in an LED array manufactured by conventional means, when electrically operated, if a latent image is formed in an area where the exposure amount is less than 0.8 times Emin, light intensity fluctuations are likely to occur between the light-emitting elements on the LED array. In the present invention, an image is formed using the average light amount of the LED array as the exposure amount for the latent image, but if we assume that each element forms one dot, light intensity fluctuations between elements will cause differences in the light area potential (Vl) in the exposed area for each dot, resulting in differences in the size and density of the one-dot image and resulting in image unevenness.

[0023] On the other hand, if the exposure amount is set high in order to improve the image fluctuation between dots of each LED element, density fluctuation of a single dot image can be suppressed. On the other hand, if an image is formed with a light amount that exceeds 1.1 times Emin, that is, the image is formed at Vl, which is in the region called residual potential in the potential-exposure curve, and the charge generated by exposure tends to remain in the photosensitive layer, often the charge generation layer, which often causes problems with ghost images.

[0024] For the above reasons, it is important to determine the light amount Emin, which is the minimum value of the normalized radius of curvature R obtained from the normalized graph, and control the exposure amount during image formation to a light amount that satisfies 0.8×Emin to 1.1×Emin.Furthermore, it is preferable to control the light amount to a light amount that satisfies 0.9×Emin to 1.0×Emin.

[0025] In the electrophotographic device of the present invention, the minimum value of the normalized radius of curvature R defined by formula (E1) is preferably 0.24 or less. A large minimum value of the normalized radius of curvature R is considered to represent a state in which the potential of the light area on the photoreceptor does not linearly decrease with respect to the amount of latent image exposure light, i.e., a state in which the charge generated within the photoreceptor remains within the photosensitive layer and the surface charge is not dissipated. From this perspective, a smaller minimum value of the normalized radius of curvature R is more ideal for the electrophotographic device and the electrophotographic photoreceptor used therein. Especially when used in combination with an LED array as in the present invention, a minimum value of the normalized radius of curvature R of 0.24 or less can simultaneously improve ghost images and image density unevenness due to uneven light intensity within the LED array, both of which are common issues in electrophotographic devices using LED arrays. Furthermore, the minimum value of the normalized radius of curvature R is preferably 0.21 or less.

[0026] [EV curve measurement] In the present invention, I exp -V exp The graph (EV curve) is defined as follows: In the technical field, the EV curve is sometimes measured in a laser beam printer under specific process conditions. On the other hand, in the present invention, the EV curve is not measured in the printer, but is measured only for the photoreceptor under the following conditions: That is, the EV curve in the present invention is At a temperature of 23.5°C and a relative humidity of 50%RH, the electrophotographic photoreceptor (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 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 light intensity is I exp [μJ / cm 2 the electrophotographic photosensitive member after charging is exposed to light of (4) The absolute value of the surface potential of the electrophotographic photosensitive member measured 0.06 seconds after the start of charging is V exp [V], (1) to (4) operations and measurements 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 refers to a graph where

[0027] A specific example for measuring the EV curve of the present invention will be described below, however, the actual measurement is not limited to this example as long as the above measurement can be performed. A transparent quartz glass is prepared by vapor-depositing a transparent ITO electrode on the surface to give a sheet resistance of 1,000 Ω / sq or less, and then optically polishing the entire surface (hereafter referred to as "NESA glass"). The surface of the photoconductor is brought into close contact with this NESA glass. At this time, glycerin is placed between the NESA glass and the photoconductor to ensure close contact. If the photoconductor is flat, smooth NESA glass is used, and if the photoconductor is cylindrical, curved NESA glass is used. In this state, the surface of the photoconductor can be charged by applying a voltage to the NESA glass. In addition, a voltage of 805 nm and 25 mW / cm 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.

[0028] Using the above measurement system, 25 [mW / cm 2 ] light is irradiated onto 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. 2 ] is stronger than the exposure light irradiated onto the photosensitive member in electrophotographic devices that are expected to be used in the future. 2 ] to stably and easily obtain a large amount of data on the amount of light increments, and to obtain the EV curve (I exp -V exp) can be obtained. At the same time, the above measurement method realized using this measurement system will enable evaluation of photosensitive material characteristics even when the process speed increases in recent years and in the future, and the exposure irradiation time is shortened. Furthermore, it is possible to evaluate photosensitive material characteristics even when the number of exposures decreases as the exposure method changes from a laser scanning optical system to an LED array. In particular, when the intensity is 25 [mW / cm 2 ] is a sufficiently strict EV curve measurement method that will remain in place for the future, even in light of the reciprocity law failure characteristics of photoconductors.

[0029] [Normalized graph] In the present invention, the EV graph is normalized, i.e., the V exp = 250[V], the amount of light when 1 / 2 [μJ / cm 2 ], 10·I 1 / 2 The horizontal axis I exp Let the normalized light amount be x, and then change the vertical axis V so that the value of the vertical axis of the graph becomes 1. exp The normalized surface potential is defined as y, where x=10 I 1 / 2 The graph is normalized so that y is 0 when x is 0. A graph normalized in this way is called a normalized graph. A radius of curvature calculated by the following formula (E1) for a graph with the horizontal axis x and the vertical axis y can be applied to the normalized graph. The radius of curvature calculated on the normalized graph is called the normalized radius of curvature.

number

[0030] Figure 3 shows the measured V exp and I expAn example of a graph of this is shown in Figure 4. Figure 5 is a diagram in which circles tangent to the normalized graph of Figure 4 are drawn, and the radius of each circle shown by a dotted or solid line in Figure 5 is the normalized radius of curvature in this normalized graph. The radius of the circle shown by the solid line in the figure is the smallest for the normalized radius of curvature R. The smaller the minimum value of the normalized curve radius R, the steeper the EV bending of the curve in the normalized graph. Figure 6 shows a graph showing the relationship between light intensity and normalized radius of curvature for the above photoconductor.

[0031] [Electrophotographic photoreceptor] An electrophotographic photoreceptor, simply called a photoreceptor, is used to support a toner image for forming an image on a recording material. The electrophotographic photoreceptor of the present invention has a support and a photosensitive layer. An electrophotographic photoreceptor having a support, an undercoat layer, and a photosensitive layer is preferred, and an electrophotographic photoreceptor having a support, an undercoat layer, a charge generation layer, and a charge transport layer containing a charge transport material, in this order, is more preferred. 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). First, a specific example of an electrophotographic photoreceptor having a laminated photosensitive layer will be described.

[0032] <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 treatment, blasting treatment, etc. in order to improve electrical properties and suppress interference fringes. The shape of the support may be cylindrical or film-like. The surface of the support may be subjected to a cutting treatment before use. In particular, when aluminum is used as the material, the surface may be subjected to a cutting treatment to form a support for a photoreceptor in order to prevent burrs during the manufacturing process and to improve the mechanical precision of the conductive support.

[0033] <Conductive layer> In 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 film 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.

[0034] 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. 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. 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.

[0035] 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.

[0036] 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 of this on an underlayer or a support, 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, sand mill, ball mill, or liquid collision-type high-speed disperser.

[0037] Alternatively, the surface of the support may be anodized in an acidic liquid containing an oxidizing agent and used as a conductive layer. In this case, for example, inorganic acids such as sulfuric acid and chromic acid, or organic acids such as oxalic acid and sulfonic acid, can be used as the electrolyte for the anodization treatment. Conditions such as applied voltage, current density, treatment temperature, and time can be selected depending on the type of electrolyte and film thickness. Furthermore, the anodized surface used in the electrophotographic photoreceptor of the present invention may be subjected to a sealing treatment after electrolysis. The sealing treatment may be performed using hot water treatment, steam treatment, or various sealing agents such as nickel acetate and nickel fluoride, but nickel acetate is preferred, as it can efficiently seal micropores. In particular, it is preferable to anodize the surface of an aluminum support under appropriate conditions and then provide an appropriate photosensitive layer thereon.

[0038] <Undercoat layer> An undercoat layer may be provided between the support and the charge generating layer, which improves adhesion between the layers and provides a charge injection blocking function. The undercoat layer preferably contains a resin. Alternatively, the undercoat layer may be formed as a cured film by polymerizing a composition containing a monomer having a polymerizable functional group. Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, polyvinylphenol resin, alkyd resin, polyvinyl alcohol resin, polyethylene oxide resin, polypropylene oxide resin, polyamide resin, polyamic acid resin, polyimide resin, polyamideimide resin, and cellulose resin. Examples of the polymerizable functional group possessed by the monomer having a polymerizable functional group include an isocyanate group, a blocked isocyanate group, a methylol group, an alkylated methylol group, an epoxy group, a metal alkoxide group, a hydroxyl group, an amino group, a carboxyl group, a thiol group, a carboxylic anhydride structure, and a carbon-carbon double bond.

[0039] Furthermore, for the purpose of improving electrical properties, the undercoat layer may further contain an electron transporting substance, a metal oxide, a metal, a conductive polymer, etc. Among these, it is preferable to use an electron transporting substance or a metal oxide. The undercoat layer particularly preferably contains a polyamide resin and titanium oxide particles. The polyamide resin is preferably a polyamide resin soluble in an alcohol-based solvent, such as a ternary (6-66-610) copolymer polyamide, a quaternary (6-66-610-12) copolymer polyamide, N-methoxymethylated nylon, polymerized fatty acid polyamide, polymerized fatty acid polyamide block copolymer, or copolymer polyamide containing a diamine component.

[0040] 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.

[0041] 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, etc. However, 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.

[0042] The average thickness of the undercoat layer is preferably 0.5 μm or more and 3 μm or less. When the thickness of the undercoat layer is 3 μm or less, the effect of suppressing charge accumulation is enhanced. When the thickness is 0.5 μm, leakage is more likely to occur due to a local decrease in charging performance.

[0043] A particularly preferred surface of the undercoat layer satisfies the formula (A) Ra≦50 nm and the formula (B) 0.1≦Ra / Rsm≦0.5 when the arithmetic mean roughness Ra and the mean length Rsm of the roughness curve elements are measured according to JIS B0601:2001.

[0044] The following describes the case where the charge-generating material contained in the charge-generating layer is hydroxygallium phthalocyanine. If the Ra of the undercoat layer surface is greater than 50 nm or the 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. This slows the transfer of generated charges and prevents the curvature of the normalized curve expressed by formula (E1), which is important in this case. Ra is particularly preferably 30 nm or less. If the Ra / Rsm is greater than 0.5, the recesses in the undercoat layer become deeper, preventing the hydroxygallium phthalocyanine pigment particles from entering the recesses. The binder resin penetrates between the undercoat layer and the hydroxygallium phthalocyanine pigment particles, reducing the contact area and preventing the curvature of the normalized curve expressed by formula (E1) from being sufficiently small.

[0045] In the case where the charge-generating material contained in the charge-generating layer (described later) is titanyl phthalocyanine, if the Ra of the undercoat layer surface is greater than 120 nm or the Ra / Rsm is less than 0.1, the scale of the recesses in the undercoat layer becomes larger than the scale of the titanyl phthalocyanine pigment particles, reducing the contact area. This slows down the transfer of generated charges, and the curvature of the normalized curve expressed by equation (E1), which is important in this case, does not become sufficiently small.

[0046] 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 of this on an underlayer or a support, and drying and / or curing it. 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.

[0047] <Charge generation layer> The charge generation layer is provided on the support or, if present, directly on the undercoat layer. The charge generation layer of the present invention is obtained by dispersing the phthalocyanine pigment of the present invention 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. 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.

[0048] 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.

[0049] Examples of solvents used in the charge generating layer coating liquid 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, dimethyl sulfoxide, etc. Furthermore, the solvents can be used alone or in combination of one or more.

[0050] The thickness of the charge generating layer is preferably 0.16 μm or more. When the charge generating layer is laminated on a support or an undercoat layer, the charge generated in the charge generating layer can be transferred smoothly by completely covering the underlying layer. Therefore, when the thickness of the charge generating layer is 0.16 μm or more, the coverage of the layer immediately below by the charge generating layer is improved, and the EV bending of the curve of the normalized graph obtained from the EV curve of the present invention becomes steeper.

[0051] (phthalocyanine pigment) In the present invention, it is preferable to use a phthalocyanine pigment as the charge generating material, and in particular, it is preferable to use a hydroxygallium phthalocyanine pigment or a titanyl phthalocyanine pigment. The hydroxygallium phthalocyanine pigment will now be described. The hydroxygallium phthalocyanine pigment used in the present invention may have an axial ligand or a substituent. In the present invention, the hydroxygallium phthalocyanine pigment is characterized by having crystal particles of a crystalline 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 by having a peak at 30 nm to 50 nm in a crystal particle size distribution measured using small-angle X-ray scattering, with the half-width of the peak being 50 nm or less.

[0052] 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.

[0053] 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 size.

[0054] 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.

[0055] 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.

[0056] 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 makes it possible to make the crystal particle size small and uniform to a certain extent by the time the crystal conversion is completed, making it easier to obtain the phthalocyanine pigment of the present invention.

[0057] Whether a hydroxygallium phthalocyanine pigment contains the amide compound represented by formula (A1) in its crystal particles can be 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 can be determined by analyzing the results of 1H-NMR measurements. For example, if a milling treatment using a solvent capable of dissolving the amide compound represented by formula (A1) or a post-milling washing step is performed, the resulting hydroxygallium phthalocyanine pigment is subjected to 1H-NMR measurements. If the amide compound represented by formula (A1) is detected in the measurements, it can be determined that the amide compound represented by formula (A1) is contained in the crystals.

[0058] The charge generating material may be an oxytitanyl phthalocyanine pigment. Although various crystalline forms of oxytitanyl phthalocyanine pigments are available, it is preferable to use an oxytitanyl phthalocyanine pigment having characteristic peaks at Bragg angles (2θ±0.2°) of 9.0°, 14.2°, 23.9°, and 27.1° in CuKα characteristic X-ray diffraction.

[0059] Furthermore, titanyl phthalocyanine pigments may be used as charge generating materials. The titanyl phthalocyanine pigments preferably have crystal particles of a crystalline type that exhibit peaks at Bragg angles 2θ of 9.8°±0.3° and 27.1°±0.3° in an X-ray diffraction spectrum using CuKα radiation. Furthermore, the titanyl phthalocyanine pigment preferably has a peak at 50 nm to 150 nm in the crystal particle size distribution measured using small-angle X-ray scattering, with the half-value width of the peak being 100 nm or less.

[0060] When the phthalocyanine pigment of the present invention is obtained by centrifugation, the weight ratio of the phthalocyanine pigment to the binder resin in a mixed solution of the phthalocyanine pigment and the binder resin 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 can be determined by analyzing data from 1H-NMR measurement. 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.

[0061] The powder X-ray diffraction measurement and 1H-NMR measurement of the phthalocyanine pigment contained in the electrophotographic photoreceptor 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

[0062] <Charge transport layer> The charge transport layer is disposed on the charge generating layer. The charge transport layer preferably contains a charge transport material and a resin.

[0063] 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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 of this on the underlayer, and drying it. 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. Among these solvents, ether-based solvents and aromatic hydrocarbon-based solvents are preferred.

[0068] <Single-layer photosensitive layer> A photoreceptor having a single-layer photosensitive layer can be formed by preparing a coating solution for the photosensitive layer containing a charge generating material, a charge transport material, a resin, and a solvent, forming the coating film on a support, and drying the coating film. The charge generating material, charge transport material, and resin are the same as those exemplified in the "electrophotographic photoreceptor having a multilayer photosensitive layer" above.

[0069] <Protective layer> In the present invention, a protective layer may be provided on the photosensitive layer, which can improve durability. 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.

[0070] 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 acryloyl group and a methacryloyl group. A material having charge transport capability may also be used as the monomer having a polymerizable functional group. 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.

[0071] 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.

[0072] 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 of this on the underlayer, and drying and / or curing it. 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.

[0073] [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).

[0074] During the rotation process, 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, the charged surface of the electrophotographic photosensitive member 1 is irradiated with image exposure light 4 from an exposure means (not shown), and an electrostatic latent image corresponding to the target image information is formed. In this case, the image exposure light 4 is light output from the exposure means consisting of an LED array and intensity-modulated in accordance with a time-series electric digital image signal of the target image information.

[0075] 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.

[0076] 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 remaining toner (residual toner), etc. Recently developed cleanerless systems also allow the residual toner to be removed directly by a developing device, etc. 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 can be 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. Furthermore, 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 can be integrally supported together with the electrophotographic photosensitive member 1 to form a cartridge. Furthermore, it can be made into a process cartridge 11 that is detachably attachable to the main body of the electrophotographic apparatus by using guide means 12 such as a rail of the main body of the electrophotographic apparatus. [Example]

[0077] The present invention will be described in more detail below using examples and comparative examples. The present invention is not limited to the following examples without departing from the gist of the present invention. In the following examples, "parts" are by mass unless otherwise specified. Moreover, Examples 1, 4, 5, 8 to 13, 16 to 29 and 32 are reference examples. The thickness of each layer of the electrophotographic photoreceptor in the examples and comparative examples, except for the charge generation layer, was determined by a method using an eddy current film thickness meter (Fischerscope (trademark), manufactured by Fisher Instruments) or by a method converting specific gravity from the mass per unit area. The film thickness of the charge generation layer was obtained by measuring the Macbeth density value by pressing a spectrodensitometer (trade name: X-Rite504 / 508, manufactured by X-Rite) against the surface of the photoreceptor, and then converting the value using a calibration curve previously obtained from the Macbeth density value and film thickness measurements obtained by observing a cross-sectional SEM image.

[0078] [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 a vertical sand mill with 1.0 mm diameter glass beads. The sand mill-dispersed solution was then further dispersed for 1 hour using an ultrasonic disperser (UT-205, manufactured by Sharp) to prepare undercoat layer coating solution 1. The output of the ultrasonic disperser was set to 100%.

[0079] [Preparation example of coating solution 10 for undercoat layer] In the preparation example of coating solution 1 for undercoat layer 1, 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.).

[0080] [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 this 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.

[0081] [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, followed by filtration using a filter press, which was repeated three times. Finally, freeze-drying was performed to obtain a hydroxygallium phthalocyanine pigment (hydrated hydroxygallium phthalocyanine pigment) with a solids content of 23% in a yield of 97%.

[0082] [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 (moisture cake thickness of 4 cm or less) just as it was removed from the filter press, the far infrared rays were turned off, and the temperature of the inner wall of the dryer was set to 50° C. Then, during microwave irradiation, the vacuum pump and leak valve were adjusted so that the degree of vacuum was 4.0 to 10.0 kPa. In the first step, a 4.8 kW microwave was irradiated onto the hydroxygallium phthalocyanine pigment for 50 minutes. The microwave was then 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 so that the degree of vacuum (pressure inside the dryer) was within the set value (4.0-10.0 kPa). The hydroxygallium phthalocyanine pigment was then irradiated with a 1.2 kW microwave for 5 minutes. The microwave was then 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 (i.e., this step was performed twice in total). At this point, the solids content of the hydroxygallium phthalocyanine pigment was 98%. Furthermore, in the third step, microwave irradiation was performed 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 (i.e., this step was performed twice in total). Furthermore, in the fourth step, the leak valve was adjusted to restore the degree of vacuum (pressure inside the dryer) to the above-mentioned set value (4.0 to 10.0 kPa). After that, the hydroxygallium phthalocyanine pigment was irradiated with 0.4 kW microwaves for 3 minutes, and then the microwaves were 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 (i.e., this step was performed eight times in total). Over a total of three hours, 1.52 kg of hydroxygallium phthalocyanine pigment (crystals) with a moisture content of 1% or less was obtained.

[0083] [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 paste of dichlorotitanium phthalocyanine. 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 filtration. 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.

[0084] [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.

[0085] [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). The milling was carried out at a disk rotation speed of 400 revolutions per minute. The resulting solution was filtered to remove the glass beads. Thirty parts of N-methylformamide were added to the solution, followed by filtration. The residue on the filter was thoroughly washed with tetrahydrofuran. The washed residue was then dried under vacuum to obtain 0.45 parts of hydroxygallium phthalocyanine pigment. In the X-ray diffraction spectrum using CuKα radiation, the obtained pigment had 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 the above treatment, 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.). The rotor used was product name: R14A (manufactured by Hitachi Koki Co., Ltd.), and acceleration and deceleration were performed at the shortest possible speed, 1,800 revolutions per minute. The supernatant 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 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. The resulting solution was filtered to remove the glass beads. 444 parts of cyclohexanone and 634 parts of ethyl acetate were added to this dispersion to prepare Coating Solution 1 for the CGL.

[0086] 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 charge generating layer coating solution 1 to dilute it until the concentration of the charge generating substance 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.

[0087] [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 had a peak at a Bragg angle 2θ of 27.2°±0.2° in its X-ray diffraction spectrum using CuKα radiation. Next, 12 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 glass beads with a diameter of 0.9 mm were dispersed in a sand mill (K-800, manufactured by Igarashi Machine Manufacturing Co., Ltd. (now Imex Co., Ltd.), 70 mm disk diameter, 5 disks) at a cooling water temperature of 18°C ​​for 4 hours. The dispersion was run at 1,800 revolutions per minute. The glass beads were removed by filtration. 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 70 nm with a half-width of 90 nm.

[0088] [Support Manufacturing Example S1] A cutting blade, adjusted to a cutting pitch of 100 μm, was pressed to a depth of 1.8 μm against one end of a cylindrical aluminum piece having a diameter of 30 mm and a length of 260.5 mm, and the cutting tool was fixed to a lathe. Then, while the cylindrical aluminum piece was being rotated, the cutting tool's cutting blade was moved to the other end of the cylindrical aluminum piece at a feed rate of 200 μm per rotation of the cylindrical aluminum piece, thereby obtaining a support body S1.

[0089] [Production of anodized support A1] An aluminum cylinder (JIS-A3003, aluminum alloy) with a diameter of 30 mm and a length of 260.5 mm was prepared using a manufacturing method including an extrusion process and a drawing process. The cylinder was degreased, etched for 1 minute with a 2% by weight sodium hydroxide solution, neutralized, and then washed with pure water. Next, the cylinder was immersed in a 10% by weight sulfuric acid solution at a current density of 1.0 A / dm 2 Anodization was performed at 80°C for 40 minutes to form an anodized film on the cylinder surface. Next, after rinsing with water, the cylinder was immersed in a 1 wt% nickel acetate solution at 80°C for 15 minutes for a sealing treatment. Further, the cylinder was rinsed with pure water and dried to obtain a support A1 that had been anodized 2.

[0090] [Production of anodized support A2] A support S1 was prepared. In the cleaning process, the cylinder was degreased, etched with a 2% by weight sodium hydroxide solution for 1 minute, neutralized, and then washed with pure water. Next, the cylinder was immersed in a 10% by weight sulfuric acid solution at a current density of 1.0 A / dm 2 Anodization was performed at 80°C for 20 minutes to form an anodized film on the cylinder surface. Next, after washing with water, the cylinder was immersed in a 1 wt% nickel acetate solution at 80°C for 15 minutes for a sealing treatment. Further washing with pure water and drying treatment were performed to obtain an anodized support A2.

[0091] [Photoreceptor manufacturing example 1] <Support> An aluminum cylinder having a diameter of 30 mm and a length of 260.5 mm, which was produced by a production method including an extrusion step and a drawing step, was used as a support 1 (cylindrical support).

[0092] <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 simultaneously added dropwise over a period of 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 settle the solids. 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. 250 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 to form a dispersion medium. This was placed in a vertical sand mill using 120 parts of glass beads with an average particle size of 1.0 mm, and dispersion treatment was carried out for 4 hours under conditions of a dispersion temperature of 23±3°C and a rotation speed of 1500 rpm (circumferential speed of 5.5 m / s), to obtain a dispersion. The glass beads were removed from this dispersion using a mesh. To the dispersion from which the glass beads had been removed, 0.01 parts of silicone oil (trade name: SH28 PAINT ADDITIVE, manufactured by Dow Corning Toray) 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 were added. 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 25 μm.

[0093] <Undercoat layer> The conductive layer was dip-coated with the undercoat layer coating solution prepared in accordance with Preparation Example 10 of Undercoat Layer Coating Solution 10 to form a coating film. The coating film 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 mean length of the roughness curve element Rsm, and Ra / Rsm of the resulting undercoat layer according to JIS B0601:2001 were measured and calculated. Ra was measured to be 20 nm, and Rsm was 110 nm, and Ra / Rsm was calculated to be 0.18. 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 cyclohexanenone 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 square area of ​​the undercoat layer surface, each 500 nm on a side. A NanoWorld NCR cantilever was used to obtain 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.

[0094] <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.

[0095] <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. In this way, an electrophotographic photoreceptor 1 was obtained.

[0096] [Photoreceptor manufacturing example 2] An electrophotographic photoreceptor 2 was produced in the same manner as in Photoreceptor Production Example 1, except that undercoat layer Coating Liquid 1 was used instead of undercoat layer Coating Liquid 10, and charge generation layer Coating Liquid 2 was used instead of charge generation layer Coating Liquid 1 in Photoreceptor Production Example 1. The resulting undercoat layer had an arithmetic mean roughness Ra according to JIS B0601:2001 of 100 nm, an Rsm of 220 nm, and an Ra / Rsm of 0.45.

[0097] [Photoreceptor manufacturing example 3] An electrophotographic photoreceptor 3 was produced in the same manner as in Photoreceptor Production Example 2, except that a 0.8 μm undercoat layer was formed using a coating solution prepared by dissolving 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 (trademark) CM8000, manufactured by Toray) in 90 parts of methanol and 60 parts of 1-butanol instead of undercoat layer coating solution 1 in Photoreceptor Production Example 2.

[0098] [Photoreceptor manufacturing example 4] An electrophotographic photoreceptor 4 was produced in the same manner as in Photoreceptor Production Example 1, except that a 0.8 μm undercoat layer was formed using a coating solution prepared by dissolving 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 (trademark) CM8000, manufactured by Toray) in 90 parts of methanol and 60 parts of 1-butanol instead of undercoat layer coating solution 10 in Photoreceptor Production Example 1.

[0099] [Photoreceptor manufacturing example 5] An electrophotographic photoreceptor 5 was produced in the same manner as in Photoreceptor Production Example 1, except that an anodized substrate A1 was used as the substrate instead of substrate 1 in Photoreceptor Production Example 1, and the conductive layer and undercoat layer were not applied.

[0100] [Photoreceptor manufacturing example 6] An electrophotographic photoreceptor 6 was produced in the same manner as in Photoreceptor Production Example 1, except that in Photoreceptor Production Example 1, an anodized substrate A2 was used as the substrate instead of substrate 1, and the conductive layer and undercoat layer were not applied.

[0101] [Photoreceptor manufacturing example 7] An electrophotographic photoreceptor 7 was produced in the same manner as in Photoreceptor Production Example 2, except that in Photoreceptor Production Example 2, an anodized substrate A1 was used as the substrate instead of substrate 1, and the conductive layer and undercoat layer were not applied.

[0102] [Photoreceptor manufacturing example 8] An electrophotographic photoreceptor 8 was produced in the same manner as in Photoreceptor Production Example 2, except that in Photoreceptor Production Example 1, a cut support S1 was used as the support instead of Support 1, and no conductive layer was applied.

[0103] [Table 1]

[0104] [Evaluation of electrophotographic photoreceptors] The following evaluations were carried out for the above Examples and Comparative Examples, and the results are shown in Tables 1 and 2.

[0105] <Evaluation of printed images (1-dot images) on electrophotographic photoreceptors> A modified Hewlett-Packard laser beam printer (product name: Color LaserJet Enterprise M652) was used as the electrophotographic device for evaluating printed images. The modification involved replacing the laser exposure system with an LED array. The focal distance from the photoreceptor surface of the LED array was adjusted so that the irradiation spot diameter of each LED element was 60 μm on average. The charging conditions and LED exposure amount were also variable. Each of the electrophotographic photoreceptors 1 to 8 was mounted in a black process cartridge and attached to the station of the black process cartridge, and images were output. The voltage applied to the charging member was adjusted so that the dark potential Vd was −500 V, and the light potential Vl was appropriately adjusted so that the latent image was formed with the latent image light intensity (adjusted as the average light intensity of the LED light-emitting elements on the LED array) listed in Tables 1 and 2. For example, in Example 1, electrophotographic photoreceptor 1 was used, and Emin was 0.506 μJ / cm. 2 The latent image exposure was Emin × 0.80. In the other examples and comparative examples, images were formed in accordance with the electrophotographic photosensitive members and latent image light amounts shown in Tables 1 and 2. The single dot image evaluation of the printed image was carried out by exposing at a resolution of 600 dpi in an environment of normal temperature and humidity (23°C / 50%RH), leaving a one dot interval for each exposed dot, and outputting an image pattern (isolated dot pattern). The shape of the single dot image in the output image was then evaluated using an optical microscope. Ten dots were observed under the microscope, and the size of the single dot image was calculated. A was given if the deviation (ratio of maximum to minimum values) of the size of the single dot at the 10 observed locations was 5% or less, B was given if it was 10% or less, C was given if it was 15% or less, and D was given if it was 20% or more.

[0106] <Evaluation of ghost images on electrophotographic photoreceptors> Similar to the evaluation of printed images, a modified machine was prepared and, instead of a single-dot image, the evaluation chart (dot knight pattern) shown in Figure 7 was printed to evaluate ghost images. Figure 7 (a) is an example of the input image, and (b) is an example of the output image, showing a simplified diagram of what happens when a ghost image is output based on the input image. Input image (a) consists of a portion of a black image against a white background. Output image (b) shows an example in which a ghost image appears in addition to the white and black images. In the print for ghost evaluation, the difference in density between the image density of a halftone image of a one-dot knight's-prong pattern and the image density of the ghost area was measured using a spectrodensitometer (product name: X-Rite504 / 508, manufactured by X-Rite Corporation). Image evaluation was performed at the center of the image formation area. Image density was measured for each of the halftone image and ghost area in the print for ghost evaluation. The difference in density between the image density of the halftone image area and the image density of the ghost area was defined as the ghost image density difference. The smaller the ghost image density difference, the greater the effect of suppressing the occurrence of ghost images. Ghost evaluation was performed according to the following criteria: A: ghost image density difference less than 0.01; B: ghost image density difference 0.01 or more but less than 0.02; C: ghost image density difference 0.02 or more but less than 0.04; and D: ghost image density difference 0.04 or more.

[0107] [Table 2]

[0108] From the above, it can be seen that when a photosensitive member in the present invention having a normalized radius of curvature of 0.24 or less is used and the latent image light quantity at which the normalized radius of curvature has a minimum value is expressed as Emin, if an image is formed with a light quantity of 0.8×Emin or more and 1.1×Emin, it is possible to achieve both deviation of a 1-dot image and ghost images. [Explanation of symbols]

[0109] 101:Support 102: Undercoat layer 103: Charge generating layer 104: Charge 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 photoreceptor that carries a toner image for forming an image on a recording material; a charging means for charging the electrophotographic photosensitive member; an exposure means for exposing the surface of the charged electrophotographic photosensitive member; An electrophotographic apparatus comprising: the exposure means is a light emitting diode array composed of a plurality of light emitting diode elements, The electrophotographic photosensitive member was heated 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 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 light intensity is I ｅｘｐ [μJ / cm ２ the electrophotographic photosensitive member after charging is exposed to light of (4) The absolute value of the surface potential of the electrophotographic photosensitive member measured 0.06 seconds after the start of charging is V ｅｘｐ [V], The operations and measurements from (1) to (4) are 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 The graph where V of the graph ｅｘｐ When the light intensity becomes I = 250 [V], １／２ [μJ / cm ２ ] and I ｅｘｐ = 10 I １／２ [μJ / cm ２ ] for x=1, I ｅｘｐ = 0 [μJ / cm ２ ] with x=0, V ｅｘｐ =500 [V], y=1, V ｅｘｐ = (I ｅｘｐ 10.I １／２ [μJ / cm ２ ]When V ｅｘｐ [V]) with y=0, When normalized as a normalized graph with the horizontal axis x and the vertical axis y, In the normalized graph, the minimum value of the normalized radius of curvature R calculated by the following formula (E1) is 0.21 or less, I corresponding to x where the normalized radius of curvature R is the minimum value ｅｘｐ Emin [μJ / cm ２ ], the light-emitting diode array is exposed with an average light amount in the exposure means satisfying 0.9×Emin or more and 1.0×Emin or less; Electrophotographic apparatus characterized by: [Equation 1]

2. the electrophotographic photoreceptor has a support, an undercoat layer, a charge generating layer, and a charge transport layer containing a charge transport material, in this order; the undercoat layer contains a polyamide resin and metal oxide particles; 2. The electrophotographic apparatus according to claim 1.

3. the electrophotographic photoreceptor has an undercoat layer, The surface of the undercoat layer has an arithmetic mean roughness Ra [nm] and a mean length Rsm [nm] of the roughness curve element according to JIS B0601:2001, Formula (A): Ra≦50 nm, and Formula (B): 0.1≦Ra / Rsm≦0.5 fulfill, 3. The electrophotographic apparatus according to claim 1 or 2.

4. the electrophotographic photoreceptor has a charge generating layer, the charge generating layer contains a titanyl phthalocyanine pigment as a charge generating material, the titanyl phthalocyanine pigment has crystal grains 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 radiation, the titanyl phthalocyanine pigment has a peak at 50 nm to 150 nm in a crystal particle size distribution measured using small-angle X-ray scattering, and the half-value width of the peak is 100 nm or less; 4. The electrophotographic apparatus according to claim 1.

5. the electrophotographic photoreceptor has a charge generating layer, the charge generating layer contains hydroxygallium phthalocyanine as a charge generating material, the hydroxygallium phthalocyanine pigment has crystal grains with a crystalline structure 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, the hydroxygallium phthalocyanine pigment has a peak at 30 nm to 50 nm in a crystal particle size distribution measured using small-angle X-ray scattering, and the half-value width of the peak is 50 nm or less; 4. The electrophotographic apparatus according to claim 1.

6. the electrophotographic photoreceptor has a charge generating layer, the charge generating layer has a thickness of 0.16 μm or more; 6. The electrophotographic apparatus according to claim 1.

Images