Photoreceptor, image formation device, and process cartridge

Abstract

To provide a photoreceptor with characteristics changed less by repeated use under a low-temperature and low-humidity environment, the photoreceptor suppressing increase of residual potential.SOLUTION: The photoreceptor includes a conductive support (31), an undercoat layer (32) on the conductive support, and a photosensitive layer (33) on the undercoat layer in this order, the undercoat layer containing a nylon resin, and the photoreceptor being characterized in that, when X-rays having a wavelength λ are irradiated, there exists at least one lattice spacing d having a value of at least 4.0 Å, the lattice spacing d being obtained from 2dsinθ=nλ (n is a natural number) using a diffraction angle 2θ.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Electrophotographic image forming apparatuses are fast and have high print quality, and are therefore used in fields such as copying machines and laser beam printers. These image forming apparatuses use electrophotographic photoreceptors (hereinafter sometimes referred to as "photoreceptors"), and photoreceptors that can provide good image quality, etc., even in environments with different temperatures and humidity have been proposed.

[0003] Patent Document 1 discloses that in an electrophotographic photoreceptor having a photosensitive layer on a support via an intermediate layer, the intermediate layer is formed by coating using a coating liquid in which nylon soluble in benzyl alcohol is dissolved. According to Patent Document 1, it is possible to improve image quality, particularly in high-temperature and high-humidity environments. Summary of the Invention [Problem to be solved by the invention]

[0004] However, the prior art has not adequately considered the problems that arise when a photosensitive drum is repeatedly used in a low-temperature, low-humidity environment, and has not been able to solve the problems. Repeated use in a low-temperature, low-humidity environment causes a phenomenon in which the residual potential increases. When the residual potential increases, the characteristics of the photosensitive drum change, and for example, image density, which is one of the image characteristics, becomes thin, resulting in a significant deterioration in image quality.

[0005] Therefore, an object of the present invention is to provide a photoreceptor that exhibits little change in characteristics even when repeatedly used in a low-temperature, low-humidity environment and that suppresses an increase in residual potential. [Means for solving the problem]

[0006] In order to solve the above problems, the photoreceptor of the present invention is a photoreceptor having an undercoat layer and a photosensitive layer sequentially provided on a conductive support, wherein the undercoat layer contains a nylon resin and has at least one lattice plane spacing d such that the value of the lattice plane spacing d calculated from 2dsinθ=nλ (n is a natural number) using the diffraction angle 2θ when irradiated with X-rays of wavelength λ is 4.0 Å or more. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a photoreceptor that exhibits little change in characteristics even when repeatedly used in a low-temperature, low-humidity environment and that suppresses an increase in residual potential. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic cross-sectional view showing an example of the configuration of a photoreceptor according to the present invention. [Figure 2] FIG. 2 is a schematic cross-sectional view showing another example of the configuration of the photoreceptor of the present invention. [Figure 3] FIG. 2 is a schematic cross-sectional view showing another example of the configuration of the photoreceptor of the present invention. [Figure 4] FIG. 2 is a schematic cross-sectional view showing another example of the configuration of the photoreceptor of the present invention. [Figure 5] FIG. 1 is a diagram showing a schematic view of an X-ray irradiation situation for explaining the basic principle of X-ray diffraction method. [Figure 6] FIG. 1A is a diagram for explaining Bragg diffraction conditions, and FIG. 1B is an example of an X-ray diffraction profile. [Figure 7] FIG. 1 is a diagram showing an example of the results of X-ray diffraction measurement. [Figure 8] 10A and 10B are diagrams for explaining a consideration of the mechanism of increase in residual potential. [Figure 9] 1 is a schematic diagram illustrating an example of an image forming apparatus according to the present invention. [Figure 10] 1 is a schematic diagram illustrating an example of a process cartridge according to the present invention. [Figure 11] FIG. 10 is a diagram illustrating an example of measuring the resistance of an undercoat layer. DETAILED DESCRIPTION OF THE INVENTION

[0009] The photosensitive member, image forming apparatus, and process cartridge according to the present invention will be described below with reference to the drawings. The present invention is not limited to the following embodiments, and can be modified, added, modified, deleted, and otherwise within the scope of what can be conceived by a person skilled in the art. Any embodiment that achieves the functions and effects of the present invention is within the scope of the present invention.

[0010] The photoreceptor of the present invention is a photoreceptor having an undercoat layer and a photosensitive layer sequentially provided on a conductive support, wherein the undercoat layer contains a nylon resin and has at least one lattice plane spacing d such that the value of the lattice plane spacing d obtained from 2dsinθ=nλ (n is a natural number) using the diffraction angle 2θ when irradiated with X-rays of wavelength λ is 4.0 Å or greater. The photoreceptor may also be referred to as an electrophotographic photoreceptor.

[0011] Fig. 1 is a schematic cross-sectional view showing one example of the configuration of a photoreceptor according to the present invention. In Fig. 1, an undercoat layer 32 and a single-layer photosensitive layer 33 are sequentially provided on a conductive support 31. Fig. 2 is a schematic cross-sectional view showing another example of the configuration of a photoreceptor according to the present invention. In the example of Fig. 2, a photosensitive layer consisting of an undercoat layer 32, a charge generation layer 35 mainly composed of a charge generation material, and a charge transport layer 37 mainly composed of a charge transport material are laminated on the conductive support 31.

[0012] 3 and 4 are schematic cross-sectional views showing other examples of the configuration of the photoreceptor of the present invention. Other layers such as a surface layer 39 may be provided. The surface layer 39 may be provided on the photosensitive layer, for example, for the purpose of protecting the photosensitive layer.

[0013] <Conductive support> The shape of the conductive support is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a film shape, a cylindrical shape, etc. The size of the conductive support is not particularly limited and can be appropriately selected depending on the purpose.

[0014] As other aspects of the structure and material of the conductive support, for example, plates such as aluminum, aluminum alloy, nickel, stainless steel, etc. are formed into a raw tube by a process such as Drawing Ironing method, Impact Ironing method, Extruded Ironing method, Extruded Drawing method, cutting method, etc., and then surface-treated by cutting, super finishing, polishing, etc. Also, endless nickel belts and endless stainless steel belts can be used as the conductive support.

[0015] <Undercoat layer> The undercoat layer in the present invention contains a nylon resin, and when irradiated with X-rays having a wavelength λ, there is at least one lattice plane spacing d obtained from 2dsinθ = nλ (n is a natural number) such that the value of the lattice plane spacing d is 4.0 Å or more.

[0016] <<Basic principle of X-ray diffraction method>> A technical explanation regarding the value of the lattice plane spacing d will be given. When X-rays having a wavelength (for example, 0.5 Å to 3 Å) comparable to the atomic spacing are incident on a substance in which atoms are regularly arranged, the X-rays scattered by each atom interfere with each other in a specific direction, generating strong X-rays. This is the X-ray diffraction phenomenon. The plane on which the atoms are arranged is called the lattice plane.

[0017] FIG. 5 is a diagram schematically showing the X-ray irradiation situation. X-rays are irradiated from the X-ray irradiation device 51 to the sample 53, and the X-rays are detected by the detector 52. The X-ray irradiation device 51 uses, for example, Cu for the tube. FIG. 6(A) is a diagram for explaining the diffraction conditions of Bragg. FIG. 6(B) is a diagram showing an example of an X-ray diffraction profile graph.

[0018] As can be seen from Figure 6(A), the path difference between the X-rays scattered by the first lattice plane and the X-rays scattered by the second lattice plane is 2d sin θ, where d is the lattice plane spacing. Therefore, when this path difference is an integer (n) multiple of the wavelength (λ) of the incident X-ray, the wave phases match (interference) and a strong diffracted X-ray results. θ is called the Bragg angle, and 2θ is called the diffraction angle. 2θ is the angle between the direction of the incident X-ray and the direction of the diffracted X-ray. 2d sin θ=nλ is called Bragg's formula.

[0019] By irradiating a material with incident X-rays of a known wavelength λ and measuring the diffraction angle 2θ and the X-ray intensity, an X-ray diffraction profile such as the one shown in the example of Figure 6(B) can be obtained. Then, by using Bragg's formula, the lattice spacing d of the material can be determined from the angle (2θ) of the diffraction peak. This is the basic principle of X-ray diffraction.

[0020] When X-rays are incident on a crystal in which atoms are regularly arranged, X-rays with intensified wavelengths are observed at specific angles. Since each substance forms crystals with its own unique regularity, by examining X-ray diffraction, it is possible to determine the type of compound, the lattice size of the crystal, the interplanar spacing, and so on.

[0021] <<Regarding the lattice spacing d of 4.0 Å or more>> The inventors of the present invention have conducted a detailed study of the electrical property stability of photoreceptors and found that in fatigue tests in which the photoreceptor was repeatedly used only in a low-temperature, low-humidity environment, the residual potential, which is one of the electrical properties, increased. This increase in residual potential results in a decrease in image density, which is one of the image properties, and a significant deterioration in image quality.

[0022] The present inventors investigated the cause of the residual potential caused by repeated use in a low-temperature, low-humidity environment and found that the increase in residual potential caused by rapid repeated use is related to an increase in the absolute value of the volume resistance of the undercoat layer. If the volume resistance of the undercoat layer is high, the undercoat layer acts as an electron trap that inhibits electron transport from the charge generating layer. In this case, it is presumed that the increase in residual potential caused by repeated use occurs due to electrons remaining and accumulating in the undercoat layer.

[0023] When investigating the mechanism of this problem, the inventors focused on the phenomenon in which the resistance of the undercoat layer increases only in low-temperature, low-humidity environments. The nylon resin used as the resin in the undercoat layer generally exhibits an increase in resistance at low temperatures and when its water absorption decreases. Taking this into consideration, the inventors performed X-ray diffraction measurements on the materials (e.g., fillers and resins) used in the undercoat layer and found that the crystallinity of the resin used in the undercoat layer changes depending on factors such as drying conditions.

[0024] The inventors' investigations revealed that the polyamide-derived peaks in the nylon resin used in the undercoat layer shift depending on, for example, the drying temperature conditions during the process of forming the undercoat layer. Based on this knowledge, as described above, the crystal plane spacing can be calculated by examining the peak changes in X-ray diffraction. Calculations based on the peak shift showed that the crystal plane spacing around 3.9 Å decreased and the crystal plane spacing around 4.4 Å increased depending on the drying conditions. Further investigations focused on the increase in residual potential and the crystal plane spacing in low-temperature, low-humidity environments, and noted that the size of water molecules, which is related to humidity, is approximately 3.8 Å.

[0025] The present inventors have hypothesized and verified the following mechanism for causing the above-mentioned decrease. (1) In a low-humidity environment, the amount of water in the system is small, so that the absolute number of water molecules that can be incorporated into the undercoat layer is small, resulting in an increase in the residual potential of the undercoat layer. (2) In the case of an undercoat layer having a crystal spacing (near 3.9 Å) that makes it difficult for water molecules to be incorporated, the amount of water molecules that can be incorporated is further reduced, resulting in an increase in the residual potential of the undercoat layer.

[0026] In response to the above, the inventors prepared a photoreceptor having an undercoat layer in which the peak derived from the polyamide of nylon resin was shifted, and performed fatigue tests using this photoreceptor under a low-temperature, low-humidity environment. The inventors' tests showed that photoreceptors having an undercoat layer with a crystal plane spacing larger than the size of a water molecule (approximately 3.8 Å) did not show an increase in residual potential with repeated use, and were improved.

[0027] Therefore, by providing a photoreceptor with an undercoat layer containing a nylon resin and having at least one lattice plane spacing d of 4.0 Å or greater, it is possible to suppress the increase in residual potential and reduce changes in characteristics even when repeatedly used in a low-temperature, low-humidity environment. Furthermore, one method for obtaining an undercoat layer with a lattice plane spacing d of 4.0 Å or greater is to adjust the drying temperature conditions during the undercoat layer formation process. Note that when the undercoat layer does not contain nylon resin but is made of other resins, no peak shift occurred.

[0028] X-ray diffraction measurements can be performed on the material used in the undercoat layer, on an undercoat layer prepared for measurement, or on a finished photoreceptor. Regardless of the stage at which the measurement is performed, the measurement results for the lattice spacing d will be the same. When performing X-ray diffraction measurements on the material used in the undercoat layer, the measurements should be performed under conditions (e.g., temperature and humidity) that match the conditions for preparing the undercoat layer. When measuring an undercoat layer prepared for measurement or a finished photoreceptor, the peaks will be slightly less visible, but the same results will be obtained as when measuring the material used in the undercoat layer, and the same results will be obtained for the peak positions and lattice spacing d.

[0029] Measurements are performed, for example, as follows: An aluminum tube is immersed in an undercoat coating solution or nylon resin solution (e.g., CM-8000 resin solution) and coated. The coating is pulled up under coating conditions that result in a film thickness of approximately 1.25 μm, and then a drying process is carried out to form an undercoat layer or resin layer on the aluminum tube. An X-ray diffraction measurement waveform (2θ = 5 to 90°) is obtained using an X-ray diffractometer, and the crystal plane spacing is determined from the peak (2θ).

[0030] As described above, the undercoat layer in the present invention has a lattice spacing d of 4.0 Å or more, calculated from 2dsinθ=nλ (n is a natural number) using the diffraction angle 2θ when irradiated with X-rays having a wavelength λ.

[0031] FIG. 7 shows an example of the results of X-ray diffraction measurement. FIG. 7 shows the results of X-ray diffraction measurement when the drying conditions for CM8000, an example nylon resin, are changed. FIG. 7 also illustrates an example of the results of X-ray diffraction measurement when the drying temperature of the undercoat layer is changed. 23°C can also be considered as no drying. The number of peaks corresponds to the number n. The horizontal axis is 2θ, and the vertical axis is intensity. An auxiliary line (baseline) is provided to determine peak intensity.

[0032] As shown in the figure, for example, the measurement results at 23°C show two peaks. The low-angle peak is referred to as Peak (1), and the high-angle peak is referred to as Peak (2). Measurement results at a higher drying temperature, such as 150°C, show a single peak. As the drying temperature increases, Peak (2) on the high-angle side shifts to the low-angle side. This can also be expressed as a decrease in Peak (2) on the high-angle side. When the lattice spacing d is calculated using 2d sin θ = nλ, for example, in the measurement results at 23°C, Peak (1) is 4.0 Å or greater, while Peak (2) is less than 4.0 Å. Therefore, in the measurement results at 23°C, there was one or more lattice spacings d where the lattice spacing d value was 4.0 Å or greater. At a drying temperature of 80°C, the peak shifts to the higher angle side, and it can be seen that the lattice spacing d tends to be smaller compared to the measurement results at 23°C. In contrast, there is only one peak at 150°C, and there are no planes with a spacing of 4.0 Å or less, so water molecules cannot be absorbed. From the results in FIG. 7, it can be seen that the peak derived from polyamide shifts as the drying temperature condition becomes higher, which means that the spacing between crystal planes changes due to the difference in the drying temperature of the undercoat layer.

[0033] Fig. 8 is a diagram for explaining the mechanism of the increase in residual potential, showing examples of peaks (1) and (2). In a low humidity environment (LL environment) with low absolute humidity, the amount of water in the system is small, so the saturation value of the water molecules that can be absorbed in the film is not reached, and the absolute value of the residual potential (VL) in a low humidity environment increases. Also, in films with intercrystalline spaces that make it difficult for water molecules to be absorbed (for example, films with a high drying temperature for the undercoat layer), the amount of water molecules that can be absorbed is even smaller, so the increase in residual potential (VL) due to the difference in drying temperature in a low humidity environment becomes greater. On the other hand, in a high humidity environment (HH environment) with high absolute humidity, the amount of water in the system is sufficient, so the saturation value of water molecules that can be absorbed in the film is reached. Also, even for films with intercrystalline spaces that make it difficult to absorb water molecules (for example, films with a high drying temperature for the undercoat layer), the environment is one in which a sufficient number of water molecules are present, so they can absorb a sufficient amount of water.

[0034] <<Binder resin for undercoat layer>> The undercoat layer contains a nylon resin as a binding resin (which may also be referred to as a binder resin) of the undercoat layer. As the nylon resin, copolymer nylon, methoxymethylated nylon, etc. can be used. For example, copolymer nylon obtained by copolymerizing nylon 6, nylon 66, nylon 610, nylon 12, etc. can be used.

[0035] Furthermore, for example, polymers and copolymers of vinyl compounds such as styrene, vinyl acetate, acrylic acid esters, and methacrylic acid esters, silicone resins, phenoxy resins, polysulfone resins, polyvinyl butyral resins, polyvinyl formal resins, polyester resins, cellulose ester resins, cellulose ether resins, urethane resins, phenolic resins, epoxy resins, polycarbonate resins, polyarylate resins, polyimide resins, melamine resins, alkyd resins, polyvinyl alcohol, casein, and sodium polyacrylate can also be used in combination.

[0036] <<Particles in the undercoat layer>> The undercoat layer may contain particles (fillers). The particles are not particularly limited and can be appropriately selected depending on the purpose. Examples include titanium oxide particles, silica particles, tin oxide particles, zinc oxide particles, indium oxide particles, antimony oxide particles, and ITO (indium tin oxide) particles. These may be used alone or in combination of two or more.

[0037] Among these, titanium oxide particles are preferred. Specific examples of titanium oxide that can be used include TTO-51A (primary particle diameter: 0.01 to 0.03 μm) manufactured by Ishihara Sangyo Kaisha. Composite particles of titanium oxide and alumina can also be used.

[0038] The particle size of the particles is not particularly limited and can be appropriately selected depending on the purpose, but it is preferable that the average primary particle size (volume average) is 500 nm or less. The average primary particle diameter of the particles can be determined by calculating the average values ​​of the long and short axes of particles observed at 50,000x magnification or more using a scanning electron microscope (SEM), and deriving the average value of 10 particles.

[0039] The volume resistivity of the particles is not particularly limited and can be appropriately selected depending on the purpose. 2 Ω·cm~10 11 Ω·cm is preferred.

[0040] When the undercoat layer contains particles, the content of the binder resin is not particularly limited and can be selected appropriately depending on the purpose, but is preferably 10 parts by mass to 200 parts by mass, more preferably 20 parts by mass to 100 parts by mass, and even more preferably 25 to 50 parts by mass, per 100 parts by mass of the particles.

[0041] <<Other ingredients in the undercoat layer>> The undercoat layer may contain the other components described above to stabilize the electrical properties and image quality. The other components are not particularly limited and can be appropriately selected depending on the purpose. Examples include electron transporting substances; electron transporting pigments such as polycyclic condensation systems and azo systems; silane coupling agents; zirconium chelate compounds; titanium chelate compounds; aluminum chelate compounds; fluorenone compounds; titanium alkoxide compounds; organic titanium compounds; antioxidants, plasticizers, lubricants, ultraviolet absorbers, and leveling agents. These may be used alone or in combination of two or more.

[0042] The undercoat layer preferably contains methanol and 1-propanol. Methanol dissolves copolymer nylon resins, but methanol alone can cause concerns about liquid stability over time, resulting in gelation upon standing. In response to this issue, adding an alcohol-based solvent with a higher boiling point than methanol can improve liquid stability. Among alcohol-based solvents, 1-propanol is particularly effective. Therefore, the use of methanol and 1-propanol can effectively dissolve nylon resins and improve liquid stability over time. Furthermore, the use of methanol and 1-propanol has the effect of suppressing the occurrence of surface cracks (Benard cells) when the solvent dries from the undercoat layer during coating film formation of the undercoat layer.

[0043] <<Method for forming an undercoat layer>> The method for forming the undercoat layer is not particularly limited, and the undercoat layer can be formed using an appropriate solvent and coating method. The timing for adding the binder resin to the coating liquid for forming the undercoat layer used in the coating method may be before or after the particles for the undercoat layer are dispersed.

[0044] The solvent is not particularly limited and can be appropriately selected depending on the purpose. Examples include alcohol-based solvents such as methanol, ethanol, 1-propanol, and butanol; ketone-based solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; ester-based solvents such as ethyl acetate and butyl acetate; ether-based solvents such as tetrahydrofuran, dioxane, and propyl ether; halogen-based solvents such as dichloromethane, dichloroethane, trichloroethane, and chlorobenzene; aromatic solvents such as benzene, toluene, and xylene; and cellosolve-based solvents such as methyl cellosolve, ethyl cellosolve, and cellosolve acetate. These solvents may be used alone or in combination. Among these, a mixture of methanol and 1-propanol is preferred.

[0045] The method for dispersing the particles of the undercoat layer in the undercoat layer coating liquid is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include dispersing methods using a ball mill, sand mill, vibration mill, KD mill, three-roll mill, attritor, pressure homogenizer, ultrasonic dispersion, etc.

[0046] The coating method is not particularly limited and can be appropriately selected depending on the viscosity of the coating liquid, the desired average thickness of the undercoat layer, etc. Examples include dip coating, spray coating, bead coating, and ring coating.

[0047] After coating with the undercoat layer coating liquid, the undercoat layer may be dried by heating in an oven, etc. The drying temperature for the undercoat layer is not particularly limited and can be appropriately selected depending on the type of solvent contained in the undercoat layer coating liquid, and is preferably 80°C to 200°C, and more preferably 100°C to 150°C.

[0048] <<Average thickness of undercoat layer>> The average thickness of the undercoat layer is not particularly limited and can be appropriately selected depending on the requirements of the machine in which it is installed and the electrical properties and lifespan of the electrophotographic photoreceptor to be manufactured. The lower limit is preferably, for example, 0.5 μm or more, and more preferably 0.75 μm or more. The upper limit is, for example, preferably 5.0 μm or less, more preferably 2.75 μm or less, and even more preferably 1.50 μm or less. When these ranges are satisfied, the electrical properties and lifespan of the electrophotographic photoreceptor can be improved. Furthermore, the residual potential VL can be prevented from increasing, and the image density can be prevented from decreasing.

[0049] The average thickness of the undercoat layer may be appropriately selected taking into consideration the materials contained in the photosensitive layer (e.g., the charge generating layer). For example, when the photosensitive layer contains phthalocyanine, the average thickness of the undercoat layer is more preferably 1.25 μm to 1.50 μm. In this case, the residual potential VL can be prevented from increasing, and the image density can be prevented from decreasing. The residual potential VL can be further prevented from increasing, and the image density can be further prevented from decreasing. Additionally, for example, when the photosensitive layer contains an azo pigment, the average thickness of the undercoat layer is more preferably 2.5 μm to 4.5 μm. In this case, the residual potential VL can be further prevented from increasing.

[0050] The average thickness can be measured, for example, by selecting a number of arbitrary points on the undercoat layer and calculating the average thickness at the multiple points. The average thickness is preferably measured at five points, more preferably at 10 points, and even more preferably at 20 points. The average thickness of other layers can also be calculated in the same manner. The average thickness can be measured using, for example, a micrometer.

[0051] When the photosensitive layer is a laminated type photosensitive layer having a charge generation layer and a charge transport layer described below, it is more preferable that the average thickness of the undercoat layer is 0.75 μm or more and 2.75 μm or less, and the photosensitive layer has a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material, and the average thickness of the charge transport layer is more preferably 20 μm or more and 35 μm or less. When the average thickness is equal to or greater than the lower limit, it is possible to suppress film scraping during actual use, suppress deterioration of the electrical properties of the photoreceptor, maintain chargeability, and facilitate stable toner image formation.When the average thickness is equal to or less than the upper limit, it is possible to suppress an increase in the absolute value of the residual potential, and suppress a decrease in the initial image density.

[0052] The average thickness of the undercoat layer is measured, for example, using an eddy current contact film thickness meter Fischerscope MMS (manufactured by Fischer Instruments) to measure the film thickness at six points around the drum center and calculate the average value.

[0053] <Photosensitive layer> The photosensitive layer is not particularly limited, and any known photosensitive layer can be appropriately selected depending on the purpose. The shape, size and material of the photosensitive layer are not particularly limited and can be appropriately selected depending on the purpose. The structure of the photosensitive layer is not particularly limited and can be appropriately selected depending on the purpose, and may be a single layer (single-layer type photosensitive layer, see Figure 1) or a multi-layer structure in which a charge generation layer containing a charge generation substance and a charge transport layer containing a charge transport substance are sequentially laminated (laminated type photosensitive layer, see Figure 2). Among these, a laminated type photosensitive layer is preferred, as it is advantageous in that it can achieve both high levels of electrostatic properties and durability.

[0054] <Charge generation layer> The charge generation layer is a part of the laminated photosensitive layer and has the function of generating charges upon exposure to light. The charge generation layer contains a charge generation substance as a main component and may further contain other materials as required.

[0055] <<Charge-generating materials>> Examples of the charge generating material include inorganic materials, organic materials, etc. These may be used alone or in combination of two or more.

[0056] Examples of inorganic materials include crystalline selenium, amorphous selenium, selenium-tellurium, selenium-tellurium-halogen, selenium-arsenic compounds, and amorphous silicon. Examples of amorphous silicon include those in which dangling bonds are terminated with hydrogen atoms or halogen atoms, and those doped with boron atoms, phosphorus atoms, or the like.

[0057] Known organic materials can be used, including, for example, metal phthalocyanines such as titanyl phthalocyanine and chlorogallium phthalocyanine, metal-free phthalocyanines, azulenium salt pigments, squaric acid methine pigments, symmetrical or asymmetrical azo pigments having a carbazole skeleton, symmetrical or asymmetrical azo pigments having a triphenylamine skeleton, symmetrical or asymmetrical azo pigments having a fluorenone skeleton, and perylene pigments.

[0058] Among these, titanyl phthalocyanine, chlorogallium phthalocyanine, metal-free phthalocyanine, symmetrical or asymmetrical azo pigments having a fluorenone skeleton, and symmetrical or asymmetrical azo pigments having a triphenylamine skeleton are preferred, as these can improve the electrical properties of the photoreceptor.

[0059] The material to be used may also be selected taking into consideration the exposure wavelength, and it is more preferable to use a material that is sensitive to the exposure wavelength. For example, when a laser or LED with an exposure wavelength of approximately 700 to 800 nm is used as the exposure means, it is preferable to use a phthalocyanine-based material that is sensitive to that wavelength. This allows for obtaining an intermediate potential and residual potential (VL) suitable for the device. In particular, titanyl phthalocyanine has high charge generation efficiency, which enhances these effects. Additionally, for example, when the exposure wavelength is 500 to 650 nm, it is preferable to use an azo pigment that has sensitivity to that wavelength, which makes it possible to obtain an intermediate potential and residual potential (VL) suitable for the device.

[0060] <<Binder resin for charge generation layer>> The charge generating layer contains, for example, a binder resin. The binder resin is not particularly limited and can be appropriately selected depending on the purpose. Examples include polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, polyarylate, silicone resin, acrylic resin, polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinylcarbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyamide, polyvinylpyridine, cellulose-based resin, casein, polyvinyl alcohol, and polyvinylpyrrolidone. Among these, polyvinyl butyral is preferred. Furthermore, the polymer charge transport material described below can also be used as the binder resin. These may be used alone or in combination of two or more.

[0061] The content of the binder resin is preferably 0 to 500 parts by mass, and more preferably 10 to 300 parts by mass, per 100 parts by mass of the charge generating substance.

[0062] <<Other materials in the charge generation layer>> The other materials are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include binder resins, antioxidants, plasticizers, lubricants, low molecular weight compounds such as ultraviolet absorbers, leveling agents, etc. These may be used alone or in combination of two or more.

[0063] The average thickness of the charge generating layer is not particularly limited and can be appropriately selected depending on the purpose, and is, for example, preferably 0.01 μm to 5 μm, and more preferably 0.05 μm to 2 μm. The average thickness is measured in the same manner as above.

[0064] <<Method for forming a charge generating layer>> The method for forming the charge generating layer is not particularly limited and can be appropriately selected depending on the purpose. For example, a vacuum thin film forming method, a casting method from a solution dispersion system, etc. can be mentioned.

[0065] Examples of vacuum thin film formation methods include vacuum deposition, glow discharge decomposition, ion plating, sputtering, reactive sputtering, and CVD (chemical vapor deposition), and these methods can satisfactorily form charge generation layers containing the above-mentioned inorganic and organic materials.

[0066] Examples of the casting method from a solution dispersion include a method in which the inorganic material or organic material described above is dispersed in a solvent together with a binder resin, if necessary, and the resulting dispersion is appropriately diluted and applied to provide a charge generating layer. The solvent is not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include isopropanol, acetone, methyl ethyl ketone (2-butanone), tetrahydrofuran, cyclohexanone, dioxane, dichloroethane, butanone, etc. Among these, methyl ethyl ketone, tetrahydrofuran, and cyclohexanone are preferred because of their low environmental impact. These may be used alone or in combination of two or more.

[0067] The dispersion method is not particularly limited and can be appropriately selected depending on the purpose. For example, methods using a ball mill, an attritor, a sand mill, etc. can be mentioned.

[0068] The method for applying the dispersion is not particularly limited and can be appropriately selected depending on the purpose. Examples include dip coating, spray coating, bead coating, nozzle coating, spinner coating, and ring coating.

[0069] <Charge transport layer> The charge transport layer is a layer that injects and transports charges generated in the charge generation layer and neutralizes the surface charge of the photoreceptor formed by charging, and is a part of the laminated photosensitive layer. The charge transport layer contains a charge transport material, a binder, and, if necessary, other materials.

[0070] <<Charge transport material>> The charge transport material is not particularly limited and can be appropriately selected depending on the purpose. Examples include low-molecular-weight electron transport materials, hole transport materials, and polymeric charge transport materials. Specific examples of electron transport materials include electron-accepting materials such as asymmetric diphenoquinone derivatives, fluorene derivatives, and naphthalimide derivatives. These materials may be used alone or in combination of two or more.

[0071] The hole transport material is not particularly limited and can be appropriately selected depending on the purpose. Examples thereof include poly(N-vinylcarbazole) and derivatives thereof, poly(γ-carbazolylethyl glutamate) and derivatives thereof, pyrene-formaldehyde condensates and derivatives thereof, polyvinylpyrene, polyvinylphenanthrene, polysilane, oxazole derivatives, oxadiazole derivatives, imidazole derivatives, monoarylamine derivatives, diarylamine derivatives, triarylamine derivatives, stilbene derivatives, α-phenylstilbene derivatives, aminobiphenyl derivatives, benzidine derivatives, diarylmethane derivatives, triarylmethane derivatives, 9-styrylanthracene derivatives, pyrazoline derivatives, divinylbenzene derivatives, hydrazone derivatives, indene derivatives, butadiene derivatives, pyrene derivatives, bisstilbene derivatives, and enamine derivatives. These may be used alone or in combination of two or more.

[0072] Examples of electron donating substances include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, butadiene derivatives, 9-(p-diethylaminostyrylanthracene), 1,1-bis-(4-dibenzylaminophenyl)propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives, etc. These may be used alone or in combination of two or more.

[0073] Examples of polymeric charge transport materials include polymers having a carbazole ring such as poly-N-vinylcarbazole, polymers having a hydrazone structure, polysilylene polymers, aromatic polycarbonates, etc. These may be used alone or in combination of two or more.

[0074] Compared with low-molecular-weight charge transport materials, polymeric charge transport materials are advantageous in that when a protective layer is laminated on the charge transport layer, the components constituting the charge transport layer bleed less into the protective layer, thereby preventing poor curing of the protective layer.Furthermore, the high molecular weight charge transport material has excellent heat resistance, which is advantageous in that it reduces deterioration due to the curing heat when forming the protective layer.

[0075] <<Binder resin for charge transport layer>> The charge transport layer contains, for example, a binder resin. Examples of the binder resin include thermoplastic or thermosetting resins such as polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester, polyvinyl chloride, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyvinylidene chloride, polyarylate, phenoxy resin, polycarbonate, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral, polyvinyl formal, polyvinyl toluene, poly(N-vinylcarbazole), acrylic resin, silicone resin, epoxy resin, melamine resin, urethane resin, phenolic resin, and alkyd resin. Among these, polycarbonate and polyarylate are preferred.

[0076] The content of the charge transport material is preferably 20 parts by mass to 300 parts by mass, and more preferably 40 parts by mass to 150 parts by mass, relative to 100 parts by mass of the binder resin.

[0077] <<Other materials in the charge transport layer>> If necessary, low molecular weight compounds such as antioxidants, plasticizers, lubricants, and ultraviolet absorbers, and leveling agents may be added to the charge transport layer. These may be used alone or in combination of two or more.

[0078] <<Charge transport layer thickness>> The average thickness of the charge transport layer is usually 50 μm or less, and is preferably 40 μm or less, more preferably 20 to 35 μm, from the viewpoints of resolution, responsiveness, etc. The average thickness is measured in the same manner as above.

[0079] <<Method for forming a charge transport layer>> The charge transport layer can be formed by dissolving or dispersing a mixture or copolymer mainly composed of a charge transport component and a binder component in a suitable solvent to prepare a coating solution for forming the charge transport layer, and then coating and drying the coating solution. Coating methods that can be used include dipping, spray coating, ring coating, roll coating, gravure coating, nozzle coating, and screen printing.

[0080] Examples of dispersion solvents that can be used when preparing the coating liquid for the charge transport layer include tetrahydrofuran, dioxane, toluene, dichloromethane, monochlorobenzene, dichloroethane, cyclohexanone, methyl ethyl ketone, acetone, etc. These may be used alone or in combination of two or more.

[0081] <Single-layer photosensitive layer> Next, the case where the photosensitive layer is a single-layer type photosensitive layer (see FIG. 1) will be described. The materials (charge generating substance, charge transport substance, binder resin) used in the photosensitive layer (charge generating layer, charge transport layer) having the above-described laminated structure can also be used in the single-layer photosensitive layer. In the case of the single-layer photosensitive layer, it is preferable to use the following electron transport substance in combination as the charge transport substance in order to achieve high sensitivity.

[0082] Examples of electron transport substances include electron accepting substances such as chloranil, bromanil, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro-9-fluorenone, 2,4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno[1,2-b]thiophen-4-one, 1,3,7-trinitrodibenzothiophene-5,5-dioxide, and benzoquinone derivatives.

[0083] In a single-layer photosensitive layer, the content of the charge generating substance is preferably 0.1% by mass to 30% by mass, and more preferably 0.5% by mass to 5% by mass, based on the total mass of the photosensitive layer. If the concentration of the charge generating substance is low, the sensitivity of the photosensitive member tends to decrease, while if the concentration is high, the charging property and film strength tend to decrease.

[0084] The single-layer photosensitive layer can be formed by dissolving or dispersing a charge generating material, a charge transport material, and a binder resin in a suitable solvent, applying the solution, and drying the solution. If necessary, a plasticizer, a leveling agent, an antioxidant, etc. can also be added.

[0085] The average thickness of the photosensitive layer is preferably 50 μm or less, and more preferably 25 μm or less from the viewpoint of resolution and responsiveness. The lower limit varies depending on the system used (particularly the charging potential, etc.), but is preferably 5 μm or more.

[0086] <Other layers> The other layers are not particularly limited and can be appropriately selected depending on the purpose, and examples thereof include a surface layer, etc. The surface layer 39 may be provided on the photosensitive layer for the purpose of protecting the photosensitive layer (see FIGS. 3 and 4).

[0087] The surface layer is preferably a layer containing a crosslinkable resin, a layer containing a filler, or the like, in terms of achieving high abrasion resistance. For the layer containing a crosslinkable resin, it is preferable to use a radical polymerizable monomer and a radical polymerizable compound having a charge transport structure and harden them to form a three-dimensional network structure, as this results in a surface layer with a high degree of crosslinking and high hardness.

[0088] Furthermore, the surface layer preferably contains a layer containing a filler for the purpose of improving the mechanical durability of the surface layer. In particular, when the surface layer contains the above-mentioned crosslinkable resin, the inclusion of a filler is preferred because it improves the abrasion resistance and enables the photoreceptor to be used for a longer period of time.

[0089] The filler is not particularly limited, and examples thereof include titanium oxide, tin oxide, zinc oxide, zirconium oxide, indium oxide, antimony oxide, boron nitride, silicon nitride, calcium oxide, barium sulfate, ITO, silicon oxide, colloidal silica, aluminum oxide, etc. Among these, aluminum oxide, titanium oxide, silicon oxide, and tin oxide are preferred from the viewpoint of the electrical properties of the surface layer.

[0090] The average primary particle size of the filler is preferably 0.01 μm to 0.5 μm from the viewpoint of the light transmittance and abrasion resistance of the surface layer. When the average primary particle size of the filler is 0.01 μm or more, sufficient abrasion resistance, dispersibility, etc. are obtained. On the other hand, when the average primary particle size of the filler is 0.5 μm or less, the surface roughness of the surface layer does not become too large, and the progress of abrasion of the blade cleaning member described below can be reduced. Therefore, it is advantageous in that it can prevent adverse effects such as poor toner cleaning and promotion of sedimentation of the filler in the dispersion liquid depending on the specific gravity of the filler particles, etc.

[0091] The content of the filler material in the surface layer is preferably 50% by mass or less, more preferably 30% by mass or less, based on the total solid content. The higher the content of the filler material in the surface layer, the higher the abrasion resistance. However, if the content of the filler material in the surface layer is 50% by mass or less, it is advantageous in that adverse effects such as an increase in residual potential and scattering of writing light on the surface layer, resulting in a decrease in transmittance, do not occur.

[0092] (Image forming device) Next, an embodiment of the image forming apparatus of the present invention will be described. The image forming apparatus of the present invention is characterized by comprising the photoreceptor of the present invention, an exposure means for exposing the photoreceptor, a development means for developing the photoreceptor to form a visible image, a cleaning means for cleaning the photoreceptor, and a transfer means for transferring the visible image onto a recording medium.

[0093] FIG. 9 is a schematic diagram showing an example of the image forming apparatus of the present invention. A charging device 3 is used as a charging device for charging the photoreceptor 1. This charging device may be a corotron device, a scorotron device, a solid discharge element, a needle electrode device, a roller charging device, a conductive brush device, or any other known charging method. This embodiment is particularly effective when a charging device such as a contact charging method or a non-contact proximity charging method is used, in which proximity discharge from the charging device occurs, which can cause decomposition of the photoreceptor composition.

[0094] The contact charging method is a charging method in which a charging roller, charging brush, charging blade, or the like comes into direct contact with the photosensitive member. The proximity charging method is, for example, a type in which a charging roller is placed close to the photoreceptor surface and the charging means in a non-contact manner so that there is a gap of 200 μm or less between the photoreceptor surface and the charging means. If this gap is too large, charging tends to become unstable, and if it is too small, the surface of the charging member may be contaminated if there is toner remaining on the photoreceptor. Therefore, the gap is preferably 10 μm to 200 μm, and more preferably 10 μm to 100 μm.

[0095] Next, an image exposure unit 5 is used as exposure means for forming an electrostatic latent image on the charged photoreceptor 1. The light source can be any light-emitting device, such as a fluorescent lamp, tungsten lamp, halogen lamp, mercury lamp, sodium lamp, light-emitting diode (LED), semiconductor laser (LD), or electroluminescence (EL). Various filters, such as a sharp-cut filter, band-pass filter, near-infrared cut filter, dichroic filter, interference filter, or color temperature conversion filter, can also be used to irradiate only light in a desired wavelength range.

[0096] Next, a developing unit 6 is used as a developing means for visualizing the electrostatic latent image formed on the photoreceptor 1. Development methods include one-component development using dry toner, two-component development, and wet development using wet toner. When the photoreceptor is negatively charged and imagewise exposed, in the case of reversal development, a positive electrostatic latent image is formed on the photoreceptor surface. If this is developed with negatively charged toner (electroscopic fine particles), a positive image is obtained, and if developed with positively charged toner, a negative image is obtained. When the photoreceptor is negatively charged and imagewise exposed, in the case of normal development, a negative electrostatic latent image is formed on the photoreceptor surface. If this is developed with positively charged toner (electroscopic fine particles), a positive image is obtained, and if developed with negatively charged toner, a negative image is obtained.

[0097] Next, a transfer charger 10 is used as a transfer means for transferring the toner image visualized on the photosensitive member onto a transfer body 9. A pre-transfer charger 7 may also be used to improve transfer. These transfer means can be electrostatic transfer methods using a transfer charger or bias roller, mechanical transfer methods such as adhesive transfer and pressure transfer, or magnetic transfer. The aforementioned charging means can be used for the electrostatic transfer method.

[0098] Next, a separation charger 11 and a separation claw 12 are used as means for separating the transfer body 9 from the photosensitive body 1. Other separation means that can be used include electrostatic attraction induction separation, side edge belt separation, tip grip transport, curvature separation, etc. The same type as the charging means can be used as the separation charger 11.

[0099] Next, a fur brush 14 and a cleaning blade 15 are used to clean the toner remaining on the photosensitive member after transfer. A pre-cleaning charger 13 may also be used to perform cleaning more efficiently. Other cleaning means include a web system and a magnetic brush system, and each system may be used alone or in combination.

[0100] Next, if necessary, a discharging means is used to remove the latent image on the photosensitive member. For example, a discharging lamp 2 or a discharging charger can be used as the discharging means, and the exposure light source and charging means can be used, respectively. Other processes that are not close to the photosensitive member, such as document reading, paper feeding, fixing, and paper discharge, can be performed by known methods.

[0101] The present invention relates to an image forming method and an image forming apparatus in which the electrophotographic photoreceptor according to the present invention is used as the image forming means. The image forming means may be fixedly incorporated in a copying machine, a facsimile machine, or a printer, or may be incorporated in such an apparatus in the form of a process cartridge that is detachably mounted therein.

[0102] (Process cartridge) Next, an embodiment of the process cartridge of the present invention will be described. The process cartridge of the present invention comprises the photoreceptor of the present invention and at least one means selected from a charging means, an exposure means, a developing means, and a transfer means, and may further comprise other members as necessary. The process cartridge is preferably detachably mountable to the main body of an image forming apparatus. The charging means, exposure means, developing means, and transfer means in the process cartridge can be appropriately selected from those described for the image forming apparatus of the present invention.

[0103] That is, the process cartridge of the present invention is characterized in that it includes and is supported integrally with the photosensitive member of the present invention, an exposure means for exposing the photosensitive member, a development means for developing the photosensitive member to form a visible image, a cleaning means for cleaning the photosensitive member, and at least one means selected from a transfer means for transferring the visible image onto a recording medium, and is detachably attached to an image forming apparatus.

[0104] An example of the process cartridge of the present invention is shown in Figure 10. The process cartridge for an image forming apparatus in this example is a device (component) that incorporates a photosensitive member 101 and also includes at least one of charging means 102, developing means 104, transfer means 106, cleaning means 107, and discharging means (not shown), and is detachably mountable to the main body of the image forming apparatus.

[0105] 10 shows the image forming process by the apparatus. As the photoconductor 101 rotates in the direction of the arrow, it is charged by charging means 102 and exposed by exposure means 103, forming an electrostatic latent image corresponding to the exposed image on its surface. This electrostatic latent image is developed with toner by developing means 104, and the developed toner image is transferred to a transfer body 105 by transfer means 106 and printed out. Next, after the image transfer, the surface of the photoconductor is cleaned by cleaning means 107, and the above operation is repeated again. [Example]

[0106] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples. In addition, "parts" means parts by mass.

[0107] Example 1 An electrophotographic photoreceptor (photoreceptor) of Example 1 was prepared by sequentially forming an undercoat layer, a charge generating layer, and a charge transport layer on an aluminum support according to the following procedure.

[0108] <Formation of undercoat layer> 9.88g of titanium oxide particles (Ishihara Sangyo Kaisha, Ltd. TTO-51A), 6.16g of copolymer nylon (Amilan CM8000 (Toray Industries, Inc.)) as binder resin, 70ml of methanol and 30ml of 1-propanol as dispersion solvents, and 50ml of 0.6φ zirconia balls PTZ as dispersion media were placed in a 200ml mayonnaise bottle and dispersed for 15 hours using a paint shaker. After dispersion, 35ml of methanol and 15ml of propanol were added to the container and stirred for about an hour. The dispersion media was then filtered to prepare the coating solution for the undercoat layer. This coating liquid for the undercoat layer was applied to an aluminum substrate having a diameter of 30 mm and a thickness of 0.8 mm by dip coating, and an undercoat layer having a thickness of 1.5 μm was formed without drying by heating.

[0109] <Creation of Charge Generating Agent> The titanyl phthalocyanine used as the charge generating material was prepared as follows: 29.2 g of 1,3-diiminoisoindoline was mixed with 200 ml of sulfolane, and 20.4 g of titanium tetrabutoxide was added dropwise under a nitrogen stream. After the dripping ended, the temperature was gradually raised to 180 °C, and the reaction was carried out with stirring for 5 hours while maintaining the reaction temperature between 170 °C and 180 °C. After the reaction ended, it was allowed to cool, and then the precipitate was filtered and washed with chloroform until the powder turned blue. Next, it was washed several times with methanol and further washed several times with hot water at 80 °C, and then dried to obtain crude titanyl phthalocyanine. The crude titanyl phthalocyanine was dissolved in 20 times the amount of concentrated sulfuric acid, and dropped into 100 times the amount of ice water while stirring. The precipitated crystals were filtered, and then washed with water repeatedly until the washing liquid became neutral to obtain a wet cake of titanyl phthalocyanine pigment. 2 g of the obtained wet cake was put into 20 g of tetrahydrofuran and stirred for 4 hours. 100 g of methanol was added thereto, and after stirring for 1 hour, filtration was carried out and dried to obtain titanyl phthalocyanine powder.

[0110] When the X-ray diffraction spectrum of the obtained titanyl phthalocyanine powder was measured under the following conditions, the titanyl phthalocyanine powder having a maximum peak at a Bragg angle 2θ of 27.2 ± 0.2° with respect to Cu-Kα ray (wavelength 1.542 Å), a peak at a minimum angle of 7.3 ± 0.2°, no peak in the range of 7.4 to 9.4°, and no peak at 26.3° was obtained.

[0111] <<X-ray Diffraction Spectrum Measurement Conditions>> X-ray tube: Cu Voltage: 50 kV Current: 30 mA Scanning speed: 2° / min Scanning range: 3° to 40° Time constant: 2 s

[0112] <Formation of Charge Generation Layer> 15 g of the obtained titanyl phthalocyanine powder, 8 g of polyvinyl butyral (Esrec BX-1: manufactured by Sekisui Chemical Co., Ltd.), and 500 g of methyl ethyl ketone were prepared by bead milling dispersion so that the average particle diameter of the pigment became 0.2 μm to obtain a coating liquid (Liquid A) for the charge generation layer. The coating liquid (Liquid A) for the charge generation layer was dip-coated on the undercoat layer to form a charge generation layer.

[0113] <Formation of charge transport layer> A coating liquid for a charge transport layer was prepared by dissolving 10 parts of polycarbonate (Iupilon Z200, manufactured by Mitsubishi Gas Chemical Company, Inc.), 8 parts of a charge transport material represented by the following structural formula (1), and 80 parts of tetrahydrofuran. The coating liquid for a charge transport layer was then applied onto the charge generation layer and dried at 125°C for 20 minutes to form a charge transport layer with an average thickness of 23 μm, thereby producing an electrophotographic photoreceptor. The charge transport material of the following structural formula (1) is also called a stilbene-based material (RTD-68 material).

[0114] [ka]

[0115] The film thickness was measured using an eddy current contact film thickness meter, Fischerscope MMS (manufactured by Fischer Instruments Co., Ltd.), by measuring the film thickness at six points around the drum at the center position and calculating the average value.

[0116] Example 2 An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that after the coating liquid for undercoat layer was applied, it was dried at 80° C. for 10 minutes.

[0117] Example 3 An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that after the coating liquid for undercoat layer was applied, it was dried at 90° C. for 10 minutes.

[0118] Example 4 An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that after the coating liquid for undercoat layer was applied, it was dried at 100° C. for 10 minutes.

[0119] Example 5 In forming the charge generation layer of Example 1, the following charge generation layer coating liquid (Liquid B) was used instead of the charge generation layer coating liquid (Liquid A). 6 parts by mass of a bisazo pigment represented by the following structural formula (2) was added and dispersed for 120 hours using a ball mill. 300 parts by mass of cyclohexanone was then added and dispersed for 3 hours to prepare a charge generation layer coating liquid (Liquid B) containing the bisazo pigment. An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that the charge generation layer was formed using this charge generation layer coating liquid (Liquid B).

[0120] [ka]

[0121] Example 6 An electrophotographic photoreceptor was produced in the same manner as in Example 5, except that after the coating liquid for undercoat layer was applied, it was dried at 80° C. for 10 minutes.

[0122] Example 7 <Synthesis example of gallium phthalocyanine> 30 parts of 1,3-diiminoisoindoline and 9.1 parts of gallium trichloride were added to 230 parts of quinoline, and the mixture was reacted at 200° C. for 3 hours. The product was then filtered and washed with acetone and methanol. The wet cake was then dried to obtain chlorogallium phthalocyanine crystals. These chlorogallium phthalocyanine crystals were dry-ground in an automatic mortar for 3 hours, and then 0.5 parts of chlorogallium phthalocyanine and 60 parts of 1 mm diameter glass beads were ball-milled at room temperature for 24 hours in 20 parts of a 1:10 water / chlorobenzene mixed solvent. The resulting mixture was filtered, washed with 10 parts of methanol, and dried to obtain chlorogallium phthalocyanine crystals, designated Pigment 1.

[0123] The obtained chlorogallium phthalocyanine crystal (Pigment 1) was subjected to X-ray diffraction spectrum measurement under the same conditions as in Example 1. The crystal had strong diffraction peaks at Bragg angles 2θ of 7.4°, 16.6°, 25.5°, and 28.3° with Cu-Kα radiation (wavelength 1.542 Å).

[0124] <Formation of Charge Generation Layer> Next, 10 g of the chlorogallium phthalocyanine powder obtained in Synthesis Example was added to a solution prepared by dissolving 10 g of polyvinyl butyral resin (BM-1, manufactured by Sekisui Chemical Co., Ltd.) in 500 ml of glass beads and 1,3-dioxolane, and the mixture was dispersed for 20 hours using a sand mill disperser. The resulting dispersion was filtered to remove the glass beads, and a coating liquid for the charge generating layer (Liquid C) was prepared. An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that in forming the charge generation layer in Example 1, the charge generation layer was formed using the charge generation layer coating liquid (C liquid) instead of the charge generation layer coating liquid (A liquid).

[0125] Example 8 An electrophotographic photoreceptor was produced in the same manner as in Example 7, except that after the coating liquid for undercoat layer was applied, it was dried at 80° C. for 10 minutes.

[0126] Example 9 <Synthesis example of metal-free phthalocyanine> <<Synthesis Example 1: Synthesis of titanyloxyphthalocyanine (β-type)>> 25.5 g of 1,3-diiminoisoindoline and 15.0 g of titanium tetra-n-butoxide were dissolved in 180 ml of 1-chloronaphthalene and stirred under heat at 180° C. in an oil bath. After 5 hours, the precipitated crystals were collected by filtration, washed with toluene and acetone, and dried to obtain 21.4 g of titanyloxyphthalocyanine crystals.

[0127] <<Synthesis Example 2: Synthesis of titanyloxyphthalocyanine (amorphous)>> 3.0 g of titanyl oxyphthalocyanine obtained in Synthesis Example 1 was slowly added to 150 ml of concentrated sulfuric acid cooled to approximately 0°C and dissolved. This solution was slowly poured into 1.2 L of cooled ice water to precipitate crystals. The crystals were collected by filtration, washed with water until neutral, and dried to obtain 2.6 g of amorphous titanyl phthalocyanine.

[0128] 2.0 g of the amorphous titanyl phthalocyanine obtained in Synthesis Example 2, 28.0 g of water, and 6.0 g of chlorobenzene were heated and stirred at 50°C. After 1 hour, the mixture was cooled to room temperature, and the crystals were filtered and washed with methanol to obtain metal-free phthalocyanine. This is designated as Pigment 2.

[0129] The obtained metal-free phthalocyanine crystal (Pigment 2) was subjected to X-ray diffraction spectrum measurement under the same conditions as in Example 1. The main peaks were found to be at Bragg angles 2θ of 7.6°, 9.2°, 16.8°, 17.4°, 20.4°, and 20.9° with respect to Cu-Kα radiation (wavelength 1.542 Å).

[0130] <Formation of Charge Generation Layer> Next, 15 g of the metal-free phthalocyanine obtained in Synthesis Example, 8 g of polyvinyl butyral (S-LEC BX-1: manufactured by Sekisui Chemical Co., Ltd.), and 500 g of methyl ethyl ketone were dispersed by bead milling so that the average particle size of the pigment was 0.2 μm, to prepare a coating solution for the charge generating layer (Solution D). An electrophotographic photoreceptor was prepared in the same manner as in Example 1, except that in forming the charge generation layer in Example 1, the charge generation layer was formed using the charge generation layer coating liquid (Liquid D) instead of the charge generation layer coating liquid (Liquid A).

[0131] Example 10 After the undercoat layer was applied, it was dried at 80° C. for 10 minutes, and otherwise the same procedure as in Example 9 was repeated to prepare an electrophotographic photoreceptor.

[0132] (Comparative Example 1) An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that after the coating liquid for undercoat layer was applied, it was dried at 135° C. for 10 minutes.

[0133] (Comparative Example 2) An electrophotographic photoreceptor was produced in the same manner as in Example 1, except that after the coating liquid for undercoat layer was applied, it was dried at 150° C. for 10 minutes.

[0134] (Comparative Example 3) An electrophotographic photoreceptor was produced in the same manner as in Example 5, except that after the coating liquid for undercoat layer was applied, it was dried at 135° C. for 10 minutes.

[0135] Comparative Example 4 An electrophotographic photoreceptor was produced in the same manner as in Example 5, except that after the coating liquid for undercoat layer was applied, it was dried at 150° C. for 10 minutes.

[0136] (Comparative Example 5) An electrophotographic photoreceptor was produced in the same manner as in Example 7, except that after the coating liquid for undercoat layer was applied, it was dried at 135° C. for 10 minutes.

[0137] (Comparative Example 6) An electrophotographic photoreceptor was produced in the same manner as in Example 7, except that after the coating liquid for undercoat layer was applied, it was dried at 150° C. for 10 minutes.

[0138] (Comparative Example 7) An electrophotographic photoreceptor was produced in the same manner as in Example 9, except that after the coating liquid for undercoat layer was applied, it was dried at 135° C. for 10 minutes.

[0139] (Comparative Example 8) An electrophotographic photoreceptor was produced in the same manner as in Example 9, except that after the coating liquid for undercoat layer was applied, it was dried at 150° C. for 10 minutes.

[0140] (Evaluation and Measurement) (1) X-ray diffraction measurement X-ray diffraction was measured on a film of the CM-8000 resin alone as follows. The aluminum tube was immersed in the CM-8000 resin solution and coated. The coating was pulled up under conditions that resulted in a film thickness of approximately 1.25 μm, and then a drying process was carried out to form a resin layer on the aluminum tube. X-ray diffraction measurements were performed on this resin layer. The X-ray diffraction measurement waveform (2θ = 5 to 90°) was acquired, and the crystal plane spacing was confirmed from the peak (2θ). In this way, the crystal type of the resin contained in the undercoat layer was confirmed. In addition, as shown in Figure 7, an auxiliary line (baseline) was drawn when determining the peak intensity.

[0141] (2) Resistance measurement of undercoat layer The resistance of the undercoat layer was measured using the following method. FIG. 11 is a diagram illustrating a schematic diagram of the measurement method, showing an example of a measurement for evaluating the VI characteristics of the undercoat layer. After forming the undercoat layer 32, charge generation layer 35, and charge transport layer 37 on an aluminum substrate, an electrode 54 is formed to prepare a measurement sample. A high resistivity meter 55 is connected to the undercoat layer 32 and the electrode 54, and measurements are performed. Note that, to connect the high resistivity meter 55 to the undercoat layer 32, the layer above the undercoat layer 32 may be scraped off, or a measurement area may be formed where no layer is formed on the undercoat layer 32.

[0142] [Resistance measurement] Measuring device: High resistivity meter (HP 4339A) Measurement sample: An undercoat layer, a charge generation layer, and a charge transport layer are formed on an aluminum substrate, and a 5 x 5 mm Au electrode is formed on the surface by vapor deposition. Connection: Connect the high resistivity meter to the electrode and undercoat layer Measurement conditions: The applied voltage is adjusted to the electric field strength when measuring 3 μm (applied from the AL side). Applied voltage 180 seconds, interval 30 seconds x average value of 3 times Measurement method: Place the sample in the case and check for continuity (electrodes, etc.) Apply a voltage equivalent to an electric field strength of 16.7 V / m for 3 minutes to charge the battery.

[0143] (3) Characteristics of electrophotographic photoreceptors The method for evaluating VL repeat properties is described below. In order to confirm the influence of humidity dependency on the potential of the photoconductor and to confirm the absolute humidity level in the air, the VL potential fluctuation was confirmed in the following four environments.

[0144] [4 environments] 10℃, 15%RH (absolute humidity: 1.41g / m 3 ) 23°C, 30% RH (absolute humidity: 6.16 g / m 3 ) 23°C, 54% RH (absolute humidity: 11.09 g / m 3 ) 27°C, 80% RH (absolute humidity: 20.06 g / m 3 )

[0145] (4) Half-life exposure The prepared photoreceptor was measured using a general-purpose actual sensitivity simulator (manufactured by Yamanashi Electronics Co., Ltd.) The charge was set to 800 V, and the potential was measured when the exposure energy was varied. The exposure energy when the potential reached 400 V was calculated, and the half-life exposure was measured. The half-life exposure is 0.31 μJ / cm, depending on the machine. 2 The following is considered acceptable: 0.20μJ / cm 2 A good result is if:

[0146] <Evaluation method> The evaluation method is as follows. Using a general-purpose actual sensitivity simulator (manufactured by Yamanashi Electronics Co., Ltd.), the electrophotographic photoreceptors manufactured in the examples and comparative examples were subjected to multiple cycles, with charging, exposure, and neutralization being one cycle. The charging voltage was set to 800 V, and the exposure voltage was set to 0.45 μJ / cm. 2 The potential at the first cycle was set as the initial potential, and the residual potential (VL) after 20 cycles was measured and evaluated by determining the amount of change in the residual potential (VL). A residual potential increase ΔVL of 60 or less after repeated use in a low-temperature, low-humidity environment was deemed to be acceptable. If the residual potential increase ΔVL after repeated use in a low-temperature, low-humidity environment is 60 or less, it can be said that the increase in residual potential during repeated use in a low-temperature, low-humidity environment has been suppressed. In this case, it can be said that there is little change in characteristics during repeated use in a low-temperature, low-humidity environment.

[0147] Table 1 lists the materials for the undercoat layer, the X-ray diffraction measurement results, and the charge generation layer. Table 2 lists the resistance of the undercoat layer, the residual potential increase ΔVL after repeated use, and the half-life exposure. In Table 2, the half-life exposure at a wavelength of 780 nm is marked "-" because the charge generation layer uses an azo pigment, which means that it has no sensitivity at a wavelength of 780 nm and measurement was difficult. However, this does not mean that there is a problem with use. The half-life exposure at a wavelength of 655 nm is left blank because the charge generation layer uses a phthalocyanine pigment, which means that it has no sensitivity at a wavelength of 655 nm and measurement was difficult. However, this does not mean that there is a problem with use. In the X-ray diffraction measurement results in Table 1, Peak (1) and Peak (2) correspond to the two peaks that appear around 20° in Figure 7. Peak (1) and Peak (2) are also shown in Figure 8 (1) and (2).

[0148] [Table 1]

[0149] [Table 2]

[0150] As can be seen from Tables 1 and 2, in Examples 1 to 10, when combined with the undercoat layer of the present invention, it was confirmed that the crystal plane spacing d, as confirmed from the crystalline peak of the resin used in the undercoat layer, was 4.0 Å or more. For the photoreceptors of Examples 1 to 10, the increase in residual potential after repeated use in a low-temperature, low-humidity environment (10°C, 15% RH) was at an acceptable level. In contrast, in Comparative Examples 1 to 8, the crystal plane spacing d was less than 4.0 Å, and the potential fluctuations during photoreceptor cycling in a low-temperature, low-humidity environment changed significantly, resulting in unsatisfactory photoreceptor characteristics.

[0151] Furthermore, in Examples 1 to 10, the film resistance of the undercoat layer was suppressed from increasing in absolute value in a low-temperature, low-humidity environment, and the fluctuation in residual potential during cycles when used as a photoreceptor was also small, resulting in good photoreceptor characteristics.

[0152] For example, aspects of the present invention are as follows. <1> A photoreceptor having an undercoat layer and a photosensitive layer sequentially provided on a conductive support, The undercoat layer contains a nylon resin, and has at least one lattice spacing d such that the value of the lattice spacing d calculated from 2dsinθ=nλ (n is a natural number) using the diffraction angle 2θ when irradiated with X-rays having a wavelength λ is 4.0 Å or more. A photoreceptor characterized by the above. <2> The undercoat layer contains methanol and 1-propanol. Characterized by <1> The photoreceptor according to claim 1. <3> The undercoat layer contains titanium oxide. Characterized by <1> or <2> The photoreceptor according to claim 1. <4> the average thickness of the undercoat layer is 0.75 μm or more and 2.75 μm or less; the photosensitive layer has a charge generating layer containing a charge generating material and a charge transport layer containing a charge transport material, The average thickness of the charge transport layer is 20 μm or more and 35 μm or less. Characterized by <1> from <3> 1. The photoreceptor according to any one of the preceding items. <5> The photosensitive layer contains any one of titanyl phthalocyanine, chlorogallium phthalocyanine, metal-free phthalocyanine, a symmetrical or asymmetrical azo pigment having a fluorenone skeleton, or a symmetrical or asymmetrical azo pigment having a triphenylamine skeleton. Characterized by <1> from <4> 1. The photoreceptor according to any one of the preceding items. <6> <1> from <5> a photoreceptor according to any one of the above items; an exposure means for exposing the photosensitive member; a developing means for developing the photosensitive member to form a visible image; a cleaning means for cleaning the photosensitive member; a transfer means for transferring the visible image onto a recording medium; An image forming apparatus characterized by: <7> <1> from <5> a photoreceptor according to any one of the above items; The image forming apparatus is detachably mounted on an image forming device and includes at least one unit selected from an exposure unit that exposes the photosensitive member to light, a development unit that develops the photosensitive member to form a visible image, a cleaning unit that cleans the photosensitive member, and a transfer unit that transfers the visible image onto a recording medium. A process cartridge characterized by: [Explanation of symbols]

[0153] 31 Conductive support 32 Undercoat layer 33 Single-layer photosensitive layer 35 Charge generation layer 37 Charge transport layer [Prior art documents] [Patent documents]

[0154] [Patent Document 1] Japanese Patent Application Laid-Open No. 2000-56494

Claims

1. A photoreceptor having an undercoat layer and a photosensitive layer sequentially provided on a conductive support, The undercoat layer contains a nylon resin, and has at least one lattice spacing d such that the value of the lattice spacing d calculated from 2d sin θ=nλ (n is a natural number) using the diffraction angle 2θ when irradiated with X-rays having a wavelength λ is 4.0 Å or more. A photoreceptor characterized by the above.

2. The undercoat layer contains methanol and 1-propanol 2. The photoreceptor according to claim 1.

3. The undercoat layer contains titanium oxide.

2. The photoreceptor according to claim 1.

4. the average thickness of the undercoat layer is 0.75 μm or more and 2.75 μm or less; the photosensitive layer has a charge generating layer containing a charge generating material and a charge transport layer containing a charge transport material, The average thickness of the charge transport layer is 20 μm or more and 35 μm or less.

2. The photoreceptor according to claim 1.

5. The photosensitive layer contains any one of titanyl phthalocyanine, chlorogallium phthalocyanine, metal-free phthalocyanine, a symmetrical or asymmetrical azo pigment having a fluorenone skeleton, or a symmetrical or asymmetrical azo pigment having a triphenylamine skeleton.

2. The photoreceptor according to claim 1.

6. The photoreceptor according to any one of claims 1 to 5, an exposure means for exposing the photosensitive member; a developing means for developing the photosensitive member to form a visible image; a cleaning means for cleaning the photosensitive member; a transfer means for transferring the visible image onto a recording medium; An image forming apparatus characterized by:

7. The photoreceptor according to any one of claims 1 to 5, The image forming apparatus is detachably mounted on an image forming device and includes at least one unit selected from an exposure unit that exposes the photosensitive member to light, a development unit that develops the photosensitive member to form a visible image, a cleaning unit that cleans the photosensitive member, and a transfer unit that transfers the visible image onto a recording medium. A process cartridge characterized by:

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