Electrophotographic photoreceptor, process cartridge and electrophotographic device

Abstract

To provide an electrophotographic photoreceptor that can suppress change of color of an image even when the electrophotographic photoreceptor is used repeatedly under a low-temperature and low-moisture environment involving a temperature rise and a moisture rise.SOLUTION: The electrophotographic photoreceptor sequentially includes a supporting body, an undercoat layer, a charge generation layer, and a charge transport layer. Regarding S0, S1, S2, S3, and S4 determined in a specific sequence (A), S1 / S0 is not larger than 0.34 and one of S2, S3, and S4 is a positive value and the others are negative values. Alternatively, one of S2, S3, and S4 is a negative value and the others are positive values.SELECTED DRAWING: Figure 3

Description

[Technical Field]

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

[0002] Conventionally, organic photoreceptors have been widely used as electrophotographic photoreceptors (hereinafter simply referred to as "photoreceptors") for use in electrophotographic image forming apparatuses due to their advantages of low cost and high productivity. Organic photoreceptors are configured by providing a photosensitive layer (organic photosensitive layer) using an organic material as a photoconductive substance (charge generation substance or charge transport substance) on a support. From the viewpoints of high sensitivity and diversity in material design, photoreceptors having a laminated photosensitive layer are mainstream as organic photoreceptors. A laminated photosensitive layer is configured by laminating a charge generation layer containing a charge generation substance such as a photoconductive dye or a photoconductive pigment, and a charge transport layer containing a charge transport substance such as a photoconductive polymer or a photoconductive low-molecular-weight compound.

[0003] In recent years, there has been a demand for electrophotographic apparatuses capable of forming higher quality images, and from the viewpoint of image quality stability, there is a demand for photoreceptors that suppress changes in sensitivity due to external environmental fluctuations such as temperature and humidity, as well as changes during repeated use.

[0004] Patent Document 1 describes an electrophotographic device that combines a photoconductor whose potential decay rate due to exposure has a positive characteristic with respect to temperature and humidity and a charging device whose initial charging potential has a positive characteristic with respect to temperature and humidity. By making the potential decay rate of the photoconductor and the initial charging potential of the charging device have positive characteristics with respect to temperature and humidity, when temperature and humidity fluctuate, the potential decay curves of the photoconductor in different temperature and humidity environments have a region where they intersect with each other. This cancels out fluctuations in the photodischarge characteristics of the photoconductor due to temperature and humidity fluctuations and fluctuations in the initial charging potential of the charging device, thereby suppressing fluctuations in the potential of the photoconductor due to temperature and humidity fluctuations.

[0005] Patent Document 2 describes phthalocyanine crystals obtained through a process of converting the crystal form by contacting a phthalocyanine crystal precursor with an aromatic aldehyde compound, and a photoreceptor containing the phthalocyanine crystals. By using the phthalocyanine crystals in the photoreceptor, it is possible to achieve high sensitivity and suppress fluctuations in sensitivity due to changes in humidity.

[0006] Patent Document 3 describes a photoreceptor having a specific photosensitive layer and a specific protective layer. The photoreceptor described in Patent Document 3 contains a charge-generating material in the photosensitive layer, which contains an adduct of oxytitanium phthalocyanine and a diol compound having a hydroxyl group on each of two adjacent carbon atoms. The photoreceptor described in Patent Document 3 also contains a product obtained by reacting metal oxide particles surface-treated with a compound having a reactive organic group in the protective layer. The photoreceptor having the protective layer provides excellent airtightness, suppressing fluctuations in charging characteristics and sensitivity characteristics due to changes in temperature and humidity, and suppressing fluctuations in image density during repeated use. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] Japanese Patent Application Publication No. 11-38709 [Patent Document 2] Japanese Patent Application Laid-Open No. 2008-19417 [Patent Document 3] Japanese Patent Application Laid-Open No. 2011-95298 Summary of the Invention [Problem to be solved by the invention]

[0008] With the recent trend toward smaller size and higher speed of electrophotographic devices, the inside of the electrophotographic device is prone to heat buildup during repeated use. Factors that cause temperature and humidity increases during use of the electrophotographic device include, for example, heat radiation from the fixing unit, frictional heat between the photosensitive member and the photosensitive member cleaning unit, heat radiation from heated paper during double-sided printing, and increases in temperature and humidity in the environment around the electrophotographic device due to the use of an air conditioner, etc. In particular, when used in a low-temperature, low-humidity environment, the range of temperature and humidity increases within the electrophotographic device during repeated use is large, and color variations in images due to changes in the sensitivity of the electrophotographic photosensitive member are likely to become a problem.

[0009] According to the investigations of the present inventors, the photosensitive members described in Patent Documents 1 to 3 have room for improvement in suppressing sensitivity changes due to temperature and humidity fluctuations and potential fluctuations during repeated use, and repeated use in a low-temperature, low-humidity environment can sometimes cause problems such as color fluctuations in images.

[0010] SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electrophotographic photoreceptor that suppresses color variations in images produced when used repeatedly in a low-temperature, low-humidity environment accompanied by increases in temperature and humidity. [Means for solving the problem]

[0011] The above object can be achieved by the present invention as follows. That is, the electrophotographic photoreceptor according to the present invention is an electrophotographic photoreceptor having a support, an undercoat layer, a charge generating layer, and a charge transport layer in this order, the undercoat layer contains titanium oxide particles that have been surface-treated with an organosilicon compound; When the hydrophobicity of the titanium oxide particles surface-treated with the organosilicon compound is defined as α [%], α [%] is 10% or more and 70% or less, the charge generating layer contains an oxytitanium phthalocyanine pigment or a hydroxygallium phthalocyanine pigment, the charge transport layer contains a triarylamine compound represented by the following formula (CTM-1) and a triarylamine compound represented by the following formula (CTM-2), [ka] [ka] For S0, S1, S2, S3, and S4 obtained by the following procedure (A), S1 / S0 is 0.34 or less, and Of S2, S3, and S4, one is positive and two are negative, or two are positive and one is negative. The above is characterized in that: Step (A) A1. Let T1 [℃] be the temperature of 15℃ and Φ1 [%RH] be the relative humidity of 45%RH. At temperature T1 [℃] and relative humidity Φ1 [%RH], perform the following procedure (B) to measure each I exp [μJ / cm 2 ] V exp Obtain [V]. Step (B) While rotating the electrophotographic photosensitive member at a rotation speed of 60 rpm, the following B1 to B5 are carried out. B1. Set the surface potential to 0. B2. A voltage is applied to the surface of the electrophotographic photosensitive member so that the absolute value of the surface potential becomes 500V. B3. 0.125 seconds after the voltage application is stopped, the wavelength is 655 nm and the light intensity is I exp [μJ / cm 2 ] and expose to light. B4.Measure the absolute value of the surface potential obtained 0.250 seconds after the end of voltage application as V exp Let's call it [V]. B5.I exp to 0.000μJ / cm 2 to 1.000 μJ / cm 2 up to 0.001 μJ / cm 2 Repeat B1 to B4 while changing the interval exp [μJ / cm 2 ] V exp Obtain [V]. A2. Let the temperature be 45°C (T2 [°C]) and the relative humidity be 16%RH (Φ2 [%RH]). At temperature T2 [°C] and relative humidity Φ2 [%RH], perform the following procedure (B) to measure each I exp [μJ / cm 2 ] V exp Obtain [V]. A3.V obtained in A1 exp For [V], the vertical axis is V exp [V], horizontal axis is I exp Plot and graph as I exp=0.000~0.030μJ / cm 2 The gradient k in this range is calculated, and the quantum efficiency η0(T1, Φ1) is calculated using the following formula (1).

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[0012] According to the present invention, it is possible to provide an electrophotographic photoreceptor in which color variations in images are suppressed even when used repeatedly in a low-temperature, low-humidity environment accompanied by increases in temperature and humidity. [Brief explanation of the drawings]

[0013] [Figure 1] 10 is an example of a graph showing the relationship between Vexp [V] and Iexp [μJ / cm 2 ]. [Figure 2] 1 is a graph schematically showing the relationship between the surface potential of a photosensitive member and the amount of light exposure. [Figure 3] 10 is an example of a graph showing the relationship between ΔVexp[V], ΔVa[V], ΔVb[V], and ΔVc[V] and Vexp[V]. [Figure 4] 1A and 1B are diagrams for explaining gradation in forming a halftone image using an electrophotographic device, in which (a) is a diagram showing control by analog gradation, (b) is a diagram showing control by digital gradation, (c) is a diagram showing actual gradation control, and (d) is a diagram showing the spot diameter of the laser light used for exposure. [Figure 5] 1 is a diagram showing an example of a layer structure of an electrophotographic photosensitive member according to the present invention. [Figure 6] 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. DETAILED DESCRIPTION OF THE INVENTION

[0014] The present invention will be described in detail below with reference to preferred embodiments. The electrophotographic photoreceptor according to the present invention is an electrophotographic photoreceptor having a support, a charge generating layer, and a charge transport layer in this order, the undercoat layer contains titanium oxide particles that have been surface-treated with an organosilicon compound, and when the hydrophobicity of the titanium oxide particles that have been surface-treated with the organosilicon compound is taken as α [%], the α [%] is 10% or more and 70% or less; the charge generation layer contains an oxytitanium phthalocyanine pigment or a hydroxygallium phthalocyanine pigment; and the charge transport layer contains a triarylamine compound represented by the following formula (CTM-1) and a triarylamine compound represented by the following formula (CTM-2): [ka] [ka] The following is characterized by the fact that S0, S1, S2, S3, and S4 obtained by the following procedure (A) are true: S1 / S0 is 0.34 or less, and one of S2, S3, and S4 is positive and the other two are negative, or two are positive and one is negative. Step (A) A1. Let T1 [℃] be the temperature of 15℃ and Φ1 [%RH] be the relative humidity of 45%RH. At temperature T1 [℃] and relative humidity Φ1 [%RH], perform the following procedure (B) to measure each I exp [μJ / cm 2 ] V exp Obtain [V]. Step (B) While rotating the electrophotographic photosensitive member at a rotation speed of 60 rpm, the following B1 to B5 are carried out. B1. Set the surface potential to 0. B2. A voltage is applied to the surface of the electrophotographic photosensitive member so that the absolute value of the surface potential becomes 500V. B3. 0.125 seconds after the voltage application is stopped, the wavelength is 655 nm and the light intensity is I exp [μJ / cm 2 ] and expose to light. B4.Measure the absolute value of the surface potential obtained 0.250 seconds after the end of voltage application as V exp Let's call it [V]. B5.I exp to 0.000μJ / cm 2 to 1.000 μJ / cm 2 up to 0.001 μJ / cm 2 Repeat B1 to B4 while changing the interval exp [μJ / cm 2 ] V exp [V] is obtained. V obtained by this exp [V] and I exp [μJ / cm 2 An example of a graph showing the relationship between [ ] is shown in Figure 1. A2. Let the temperature be 45°C (T2 [°C]) and the relative humidity be 16%RH (Φ2 [%RH]). At temperature T2 [°C] and relative humidity Φ2 [%RH], perform the following procedure (B) to measure each I exp [μJ / cm 2 ] Vexp Obtain [V]. A3.V obtained in A1 exp For [V], the vertical axis is V exp [V], horizontal axis is I exp Plot and graph as I exp =0.000~0.030μJ / cm 2 The gradient k in this range is calculated, and the quantum efficiency η0(T1, Φ1) is calculated using the following formula (1).

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[0015] In the above, the relative dielectric constant ε of the charge transport layer r can be determined by impedance measurement. Also, I exp [μJ / cm 2 ]=3.414·I 1 / 2 [μJ / cm 2 ] when V exp V defined as [V] R [V] means the potential when the surface potential of the photoconductor is reduced to the point where it no longer decreases substantially due to exposure. Also, the amount of light required to reduce the surface potential of the photoconductor to the point where it no longer decreases substantially is 3.414 I. 1 / 2 [μJ / cm 2 ] is determined as follows:

[0016] Figure 2 is a graph showing a schematic relationship between the surface potential of a photosensitive member and the amount of light exposure. The vertical axis represents the surface potential, and the horizontal axis represents the amount of light exposure. The relative value of the surface potential at the time of initial charging is 1, and when the surface potential is reduced to the point where it no longer substantially decreases, the relative value of the surface potential is 0 and the relative value of the amount of light is 1. The amount of light at an initial surface potential of 1 is 0. The curve obtained from this can be expressed as a quadratic function y=(x-1) 2 In this case, in the above quadratic function, the relative value of the light intensity at the point where the relative value of the surface potential is 0 is 1, which is 3.414 times the light intensity (1-√2 / 2) at the point where the initial relative value of the surface potential is half, as shown in Figure 2.

[0017] From the above, in the above procedure (A), the light intensity I required to reduce the surface potential of 500 V at the initial charging (B2 in procedure (B)) to half, 250 V, is 1 / 2 [μJ / cm 2 ], multiplied by 3.414, and V R The amount of light required to obtain [V] is the amount of light required to obtain [V]. This means that the sensitivity of the surface potential to light exposure varies depending on the photoconductor, but V is calculated by taking into account the difference in sensitivity of each photoconductor. R The amount of light required to obtain [V] can be determined.

[0018] ΔV in the above procedure (A) a [V], ΔV b [V], and ΔV c [V] is ΔV exp The contributions to [V] are separated into residual voltage, quantum efficiency, and recombination constant. exp [V], ΔV a [V], ΔV b [V], and ΔV c [V] and V exp An example of a graph showing the relationship with [V] is shown below.

[0019] When determining S0, S1, S2, S3, and S4, |ΔV exp |[V], ΔV a [V], ΔV b [V], and ΔV c [V], respectively V exp [V](T1,Φ1) is V R Integrate in the range from [V] to 500V. In other words, by the above procedure (A), ΔV exp The contributions of the residual voltage, quantum efficiency, and recombination constant to V R The overall evaluation ranges from [V] to the surface potential (500V) at the time of initial charging. The reason for this is as follows.

[0020] FIG. 4 is a diagram illustrating gradation in halftone image formation using an electrophotographic device. FIG. 4 shows an example in which the image resolution is 600 dpi and one dot is 42 μm × 42 μm. As shown in FIG. 4(a), analog gradation controls the gradation by the surface potential of the photoconductor, which can be considered macroscopic control. On the other hand, digital gradation controls the gradation by the area ratio, which can be considered microscopic control, as shown in FIG. 4(b). In actual image formation, as shown in FIG. 4(d), the spot diameter w of the laser used to expose the photoconductor has a certain width. Therefore, as shown in FIG. 4(c), gradation is controlled based on both analog gradation and digital gradation. That is, analog gradation is used where the spot diameter w is sufficiently larger than one dot, and digital gradation is used where the spot diameter w is sufficiently smaller than one dot.

[0021] Therefore, in the actual formation of halftone images, not only the surface potential after exposure but also the fluctuations due to temperature and humidity over the entire range of the surface potential from the surface potential at the time of initial charging to the surface potential after exposure affect the halftone density. Therefore, in the present invention, the contribution of temperature and humidity changes to the fluctuations in surface potential is expressed as V R The overall evaluation ranges from [V] to a surface potential of 500V at the time of initial charging.

[0022] The present inventors speculate as follows about the reason why the electrophotographic photoreceptor according to the present invention can suppress color variation of an image when repeatedly used in a low-temperature, low-humidity environment accompanied by increases in temperature and humidity.

[0023] First, in the electrophotographic photoreceptor according to the present invention, the contribution of residual charge to fluctuations in sensitivity of the photoreceptor due to changes in temperature and humidity is small, and S1 / S0 is a certain value or less. This suppresses fluctuations in the number of accumulated charges in the photoreceptor due to changes in temperature and humidity, and therefore it is believed that, in repeated use accompanied by increases in temperature and humidity, an increase in accumulated charges due to repeated use can also be suppressed, thereby suppressing fluctuations in sensitivity of the photoreceptor. If the value of S1 / S0 is 0.34 or less at T1=15°C, Φ1=45% RH, T2=45°C, and Φ2=16% RH, fluctuations in the sensitivity of the photosensitive member during repeated use are suppressed. S1 / S0 is preferably 0.28 or less. In addition, the absolute value of the difference between the residual power at T1=15°C, Φ1=45%RH and the residual power at T2=45°C, Φ2=16%RH |ΔV r It is preferable that [V]| is 20 V or less. r By keeping [V]| at 20 V or less, the influence of the accumulated charge can be further suppressed.

[0024] Second, one of the three factors that contribute to sensitivity fluctuations in a photoconductor due to temperature and humidity changes—quantum efficiency, recombination constant, and residual voltage—has a negative contribution to the other two. That is, one of S2, S3, and S4 is positive and the other two are negative, or two are positive and one is negative. As a result, even if the temperature and humidity inside the electrophotographic device increase with repeated use of the photoconductor, and the contributions of the three factors—quantum efficiency, recombination constant, and residual voltage—to the photoconductor sensitivity fluctuations increase, the contribution of one factor acts in the opposite direction to the contributions of the other two factors. This cancels out the fluctuations in photoconductor sensitivity, suppressing the overall fluctuations in the photoconductor sensitivity due to temperature and humidity changes.

[0025] It is speculated that these two mechanisms are what suppress fluctuations in sensitivity of the photoreceptor when used repeatedly under low temperature and low humidity conditions with rising temperature and humidity. The configuration of the photoreceptor according to the present invention will be specifically described below.

[0026] [Electrophotographic photoreceptor] The electrophotographic photoreceptor according to the present invention has a support, an undercoat layer, a charge generation layer, and a charge transport layer in this order. Fig. 5 is a diagram showing an example of the layer structure of an electrophotographic photoreceptor. In Fig. 5, 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).

[0027] <Support> In the present invention, the support is preferably a conductive support having electrical conductivity. Examples of the conductive support include a support formed of a metal or alloy such as aluminum, iron, nickel, copper, or gold, and a support having a thin film of a metal such as aluminum, chromium, silver, or gold, a thin film of a conductive material such as indium oxide, tin oxide, or zinc oxide, or a thin film of a conductive ink containing silver nanowires formed on an insulating support such as a polyester resin, a polycarbonate resin, a polyimide resin, or glass. The surface of the support may be subjected to electrochemical treatment such as anodization, wet honing, blasting, cutting, etc. in order to improve electrical properties and suppress interference fringes. The shape of the support may be cylindrical, film-like, etc.

[0028] <Conductive layer> In the photoreceptor according to the present invention, a conductive layer may be provided on the support, which makes it possible to cover unevenness and defects in the support and prevent interference fringes.

[0029] The conductive layer preferably contains conductive particles and a binder resin. Examples of conductive particles include particles made of carbon black, metals, and metal oxides. Examples of 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 metals include aluminum, nickel, iron, nichrome, copper, zinc, and silver. Among these, metal oxide particles are preferred, and titanium oxide, tin oxide, and zinc oxide are particularly preferred. When metal oxide particles are used as conductive particles, the surfaces of the metal oxide particles may be treated with a silane coupling agent or the like, or the metal oxide particles may be doped with elements such as phosphorus or aluminum or their oxides. Examples of doped elements and their oxides include phosphorus, aluminum, niobium, and tantalum. The conductive particles may also have a laminated structure comprising a core particle and a coating layer covering the particle. Examples of materials for the core particle include titanium oxide, barium sulfate, and zinc oxide. Examples of materials for 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 of the metal oxide particles is preferably 1 nm or more and 500 nm or less, and more preferably 3 nm or more and 400 nm or less.

[0030] Examples of the resin include polyester resin, polycarbonate resin, polyvinyl acetal resin, acrylic resin, silicone resin, epoxy resin, melamine resin, polyurethane resin, phenol resin, alkyd resin, etc. The conductive layer may further contain silicone oil, resin particles, a masking agent such as titanium oxide, etc.

[0031] The thickness of the conductive layer is preferably 1 μm or more and 50 μm or less, and more preferably 3 μm or more and 40 μm or less. The conductive layer can be formed by preparing a conductive layer coating liquid containing the above-mentioned materials and solvent, forming a coating film from this, and drying it. Examples of solvents used in the coating liquid 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 conductive particles in the conductive layer coating liquid include methods using a paint shaker, sand mill, ball mill, and liquid collision-type high-speed disperser.

[0032] <Undercoat layer> In the photoreceptor according to the present invention, an undercoat layer is provided between the support or the conductive layer and the charge generating layer, and the undercoat layer preferably contains a polyamide resin and titanium oxide particles.

[0033] 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.

[0034] From the viewpoint of suppressing charge accumulation, the titanium oxide particles preferably have a rutile or anatase crystal structure, and more preferably a rutile crystal structure with weaker photocatalytic activity. If the crystal structure is a rutile crystal structure, 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 of the titanium oxide particles is preferably 10 nm or more and 100 nm or less, and more preferably 30 nm or more and 60 nm or less.

[0035] The undercoat layer contains titanium oxide particles surface-treated with an organosilicon compound, and when the hydrophobicity of the titanium oxide particles treated with the organosilicon compound is defined as α [%], the α [%] is preferably 10% to 70%. By setting the hydrophobicity α to 10% to 70%, charge accumulation can be suppressed and the influence of humidity changes can be reduced.

[0036] The hydrophobicity degree α can be determined by measuring the methanol wettability of titanium oxide particles that have been surface-treated with an organosilicon compound. The methanol wettability is measured, for example, using a powder wettability tester (trade name: WET100P, manufactured by Rhesca) as follows. 0.2g of titanium oxide particles that have been surface-treated with an organosilicon compound and 50g of ion-exchanged water are added to a 200ml beaker, and methanol is added dropwise while slowly stirring the beaker with a buret. When the amount of methanol added reaches 10% light transmittance inside the beaker, the hydrophobicity value α is calculated using formula (vii): α = 100 × a / (a + 50).

[0037] In addition to the above, the undercoat layer may contain additives such as organic particles and a leveling agent for the purpose of improving the film-forming properties of the undercoat layer, 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.

[0038] The thickness of the undercoat layer is preferably 0.5 μm or more and 3 μm or less. If the thickness of the undercoat layer is 3 μm or less, the effect of suppressing charge accumulation can be highly obtained. If the thickness is 0.5 μm or more, the occurrence of leakage due to a local decrease in charging performance can be suppressed.

[0039] The undercoat layer can be formed by preparing a coating solution for the undercoat layer containing the above-mentioned materials and solvent, forming a coating film from the coating solution, and drying and / or curing the coating film. Examples of solvents used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Examples of dispersion methods for dispersing titanium oxide particles in the coating solution for the undercoat layer include ultrasonic dispersion, methods using a paint shaker, a sand mill, a ball mill, and a high-speed liquid collision disperser.

[0040] <Charge generation layer> The charge generation layer is provided on the undercoat layer in contact with the undercoat layer. The charge generation layer is obtained by dispersing 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 it. 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 simultaneously 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. The content of the charge generating material in the charge generating layer is preferably 30% by mass or more and 85% by mass or less, and more preferably 60% by mass or more and 80% by mass or less, based on the total mass of the charge generating layer.

[0041] 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, polyvinylanthracene, and polyvinylpyrene can also be used. The binder resins may be used alone or in combination, either as a mixture or as a copolymer.

[0042] 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. The solvents may be used alone or in combination of two or more.

[0043] Examples of charge generation materials used in the charge generation layer include azo pigments, perylene pigments, polycyclic quinone pigments, indigo pigments, and phthalocyanine pigments. Among these, phthalocyanine pigments are preferred, and oxytitanium phthalocyanine pigments and hydroxygallium phthalocyanine pigments are more preferred. The oxytitanium phthalocyanine pigments and hydroxygallium phthalocyanine pigments may have an axial ligand or a substituent.

[0044] Furthermore, the hydroxygallium phthalocyanine pigment preferably has crystal particles of a crystal type that exhibits peaks at Bragg angles 2θ of 7.4°±0.3° and 28.2°±0.3° in an X-ray diffraction spectrum using CuKα radiation.

[0045] 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. [ka] (In the above formula (A1), R 1 represents a methyl group, a propyl group, or a vinyl group. Examples of the amide compound represented by formula (A1) include N-methylformamide, N-propylformamide, and N-vinylformamide.

[0046] Furthermore, 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, relative to the content of the crystal particles. By making the content of the amide compound represented by formula (A1) 0.1% by mass to 3.0% by mass relative to the content of the crystal particles, the size of the crystal particles can be made uniform to an appropriate size.

[0047] The phthalocyanine pigment having crystal particles containing the amide compound represented by formula (A1) is obtained by a step of converting the crystal structure of the phthalocyanine pigment obtained by the acid pasting method and the amide compound represented by formula (A1) by wet milling treatment.

[0048] 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 solvents used in the milling treatment 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.

[0049] The presence of crystal particles containing the amide compound represented by formula (A1) in the hydroxygallium phthalocyanine pigment obtained by the above process can be confirmed as follows. Specifically, the obtained hydroxygallium phthalocyanine pigment is subjected to 1H-NMR measurement, and the data obtained thereby is analyzed. Furthermore, the content of the amide compound represented by formula (A1) in the crystal particles can be determined by analyzing the results of the 1H-NMR measurement. For example, when a milling treatment using a solvent capable of dissolving the amide compound represented by formula (A1) or a washing step after milling is performed, the obtained hydroxygallium phthalocyanine pigment is subjected to 1H-NMR measurement. If the amide compound represented by formula (A1) is detected, it can be determined that the amide compound represented by formula (A1) is contained in the crystals.

[0050] Powder X-ray diffraction measurement and 1H-NMR measurement of the phthalocyanine pigment contained in the electrophotographic photosensitive member can be carried out, for example, 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

[0051] The present inventors have found that when an oxytitanium phthalocyanine pigment and the hydroxygallium phthalocyanine pigment are used as charge-generating materials, the following occurs: the contribution S3 of quantum efficiency to photosensitive material sensitivity due to changes in temperature and humidity becomes negative, while the contributions S2 and S4 of residual charge and recombination constant become positive. Generally, as the temperature and humidity of a photosensitive material increase, the quantum efficiency improves, i.e., the contribution S3 of quantum efficiency becomes positive. Although the inventors are not sure why S3 becomes negative when an oxytitanium phthalocyanine pigment and the hydroxygallium phthalocyanine pigment are used as charge-generating materials, they speculate as follows.

[0052] The following factors are thought to increase and decrease quantum efficiency in environments where the temperature and humidity of photoreceptors increase. Factors that increase quantum efficiency include an increase in the separation efficiency of electrons and holes due to an increase in temperature, and an increase in the dielectric constant due to water adsorption to the charge-generating material due to an increase in humidity. On the other hand, factors that decrease quantum efficiency include charges present at the interface of the charge-generating layer opposite the charge-transport layer migrating to the interface on the charge-transport layer side due to an increase in humidity, weakening the local electric field strength of the charge-generating layer. The increase or decrease in total quantum efficiency depends on the magnitude of these two factors. When using oxytitanium phthalocyanine pigments, charge migration at the charge-generating layer interface is more likely to occur as humidity increases. As a result, quantum efficiency decreases and S3 becomes negative when temperature and humidity increase. Furthermore, when using the hydroxygallium phthalocyanine pigment, the increase in electron-hole separation efficiency due to an increase in temperature is small, so the local electric field strength of the charge-generating layer due to an increase in humidity becomes relatively large. As a result, quantum efficiency decreases and S3 becomes negative when temperature and humidity increase. The reason why S3 tends to be negative when an oxytitanium phthalocyanine pigment or the hydroxygallium phthalocyanine pigment is used is presumed to be as described above, but the use of these charge generating substances does not always result in negative S3; S3 becomes negative only when the substance is combined with a layer other than the charge generating layer of the electrophotographic photosensitive member.

[0053] <Charge transport layer> The charge transport layer preferably contains a charge transport material and a resin.

[0054] 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 enamine compounds are preferred from the viewpoint of suppressing charge retention in the charge transport layer. The content of the charge transport material in the charge transport layer is preferably 25% by mass to 70% by mass, and more preferably 40% by mass to 65% by mass, based on the total mass of the charge transport layer.

[0055] 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 10:10 to 16:10.

[0056] 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.

[0057] The thickness of the charge transport layer is preferably 8 μm to 40 μm, more preferably 8 μm to 17 μm, which can prevent charges from accumulating in the charge transport layer.

[0058] The charge transport layer can be formed by preparing a coating solution for the charge transport layer containing the above-mentioned materials and solvent, forming a coating film from the coating solution, and drying the coating film. Examples of the solvent used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents. Among these solvents, ether-based solvents and aromatic hydrocarbon-based solvents are preferred.

[0059] <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.

[0060] 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.

[0061] The protective layer may contain additives such as antioxidants, ultraviolet absorbers, plasticizers, leveling agents, slippage-imparting agents, abrasion resistance improvers, etc. Specific examples of the 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.

[0062] The 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.

[0063] The protective layer can be formed by preparing a coating solution for the protective layer containing the above-mentioned materials and solvent, forming a coating film from this, and drying and / or curing the coating film. Examples of the solvent used in the coating solution include alcohol-based solvents, ketone-based solvents, ether-based solvents, sulfoxide-based solvents, ester-based solvents, and aromatic hydrocarbon-based solvents.

[0064] [Process cartridge and electrophotographic device] The electrophotographic apparatus according to the present invention comprises an electrophotographic photosensitive member, a charging means, an exposure means, a developing means and a transfer means.

[0065] An example of the schematic configuration of an electrophotographic apparatus having a process cartridge equipped with an electrophotographic photosensitive member is shown in Figure 6. In Figure 6, a cylindrical (drum-shaped) electrophotographic photosensitive member 1 is driven to rotate around an axis 2 in the direction of the arrow at a predetermined peripheral speed (process speed).

[0066] During rotation, the surface of the electrophotographic photosensitive member 1 is charged to a predetermined positive or negative potential by charging means 3. Next, exposure light 4 is irradiated from exposure means (not shown) onto the charged surface of the electrophotographic photosensitive member 1, and an electrostatic latent image corresponding to the target image information is formed. The exposure light 4 is light whose intensity is modulated in accordance with a time-series electric digital image signal of the target image information, output from exposure means such as slit exposure or laser beam scanning exposure.

[0067] 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.

[0068] 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 then conveyed to 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 cleaning means 9 to remove any adhering matter such as toner (residual toner after transfer). With a cleanerless system recently developed, the residual toner after transfer can also be removed directly by a developing device or the like. Furthermore, the surface of the electrophotographic photoreceptor 1 is subjected to a charge removal process using pre-exposure light 10 from a pre-exposure means (not shown) before being used repeatedly for 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.

[0069] The process cartridge according to the present invention integrally supports the electrophotographic photosensitive member 1 and at least one means selected from the group consisting of the charging means 3, the developing means 5, and the cleaning means 9, and is detachably mountable to the main body of the electrophotographic apparatus. For example, as shown in FIG. 6, the process cartridge according to the present invention can be a process cartridge 11 that is detachably mountable to the main body of the electrophotographic apparatus using a guide means 12 such as a rail of the main body of the electrophotographic apparatus. When the electrophotographic apparatus is a copier or printer, the exposure light 4 may be light reflected from or transmitted through an original. Alternatively, the exposure light 4 may be light emitted by scanning a laser beam, driving an LED array, or driving a liquid crystal shutter array in accordance with a signal obtained by reading the original with a sensor and converting it into a signal.

[0070] The electrophotographic photoreceptor 1 according to the present invention can be widely applied to electrophotographic application fields such as laser beam printers, CRT printers, LED printers, FAX machines, liquid crystal printers, and laser plate making. [Example]

[0071] The present invention will be described in more detail below using examples and comparative examples. In the following description, Examples 9 to 13, 25 to 34, 46 to 50, 57, and 58 are each reference examples.The present invention is not limited in any way by the following examples, provided that the gist of the invention is not exceeded. In the following description of the examples, "parts" are by mass unless otherwise specified.

[0072] The film thickness of each layer of the electrophotographic photoreceptors produced 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, manufactured by Fisher Instruments) or by a method of converting the mass per unit area into specific gravity.

[0073] The film thickness of the charge generating layer was measured as follows. A spectrodensitometer (trade name: X-Rite504 / 508, manufactured by X-Rite) was pressed against the surface of the photoreceptor to measure the Macbeth density value. A calibration curve was also obtained in advance from film thickness measurements obtained by observing cross-sectional SEM images. The Macbeth density value and the calibration curve were then used to convert the Macbeth density value of the photoreceptor to determine the film thickness of the charge generating layer.

[0074] <Preparation of Coating Solution 1 for Conductive Layer> The substrate was anatase titanium oxide with an average primary particle size of 200 nm. A titanium niobium sulfate solution containing 33.7 parts titanium (calculated as TiO2) and 2.9 parts niobium (calculated as Nb2O5) was prepared. 100 parts of the substrate was dispersed in pure water to prepare 1,000 parts of a suspension, which was then heated to 60°C. The titanium niobium sulfate solution prepared above and 10 mol / L sodium hydroxide were added dropwise to the suspension over 3 hours to adjust the pH of the suspension to 2-3. After the entire amount was added, the pH was adjusted to near neutral, and a polyacrylamide-based flocculant was added to precipitate the solids. The supernatant was removed, filtered, washed, and dried at 110°C to obtain an intermediate containing 0.1 mass% of organic matter derived from the flocculant, calculated as carbon. This intermediate was calcined in nitrogen at 750°C for 1 hour, and then calcined in air at 450°C to produce titanium oxide particles. The resulting 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, 50 parts of a phenolic resin as a binder resin was dissolved in 35 parts of a solvent to obtain a solution. The phenolic resin was a phenolic resin (monomer / oligomer of phenolic resin) (trade name: Plyofen J-325, manufactured by DIC, resin solid content: 60%, density after curing: 1.3 g / cm). 2 ) was used. As the solvent, 1-methoxy-2-propanol was used. To this solution, 60 parts of titanium oxide particles 1 were added, and the mixture was placed in a vertical sand mill using 120 parts of glass beads with an average particle size of 1.0 mm as a dispersion medium. Dispersion treatment was carried out for 4 hours at a dispersion temperature of 23±3°C and a rotation speed of 1500 rpm (circumferential speed of 5.5 m / s), yielding a dispersion. The glass beads were removed from the dispersion using a mesh. 0.01 parts of a leveling agent and 8 parts of a surface roughness imparting agent were added to the dispersion after removing the glass beads and stirred. Silicone oil (trade name: SH28 PAINT ADDITIVE, manufactured by Dow Corning Toray) was used as the leveling agent. Silicone resin particles (trade name: KMP-590, manufactured by Shin-Etsu Chemical Co., Ltd., average particle size: 2 μm, density: 1.3 g / cm) were used as the surface roughness imparting agent. 3 Thereafter, the solution was filtered under pressure using a PTFE filter paper (trade name: PF060, manufactured by Advantec Toyo Co., Ltd.) to prepare a conductive layer coating solution 1.

[0075] <Preparation of Coating Solution 2 for Conductive Layer> The following materials were prepared: 214 parts of titanium oxide (TiO2) particles coated with oxygen-deficient tin oxide (SnO2) as metal oxide particles 132 parts of phenolic resin (phenolic resin monomer / oligomer) as a binder resin (product name: Plyofen J-325, manufactured by Dainippon Ink and Chemicals, Inc., resin solid content: 60% by mass) 98 parts of 1-methoxy-2-propanol as solvent These were placed in a sand mill using 450 parts of 0.8 mm diameter glass beads and dispersed at a rotation speed of 2000 rpm for 4.5 hours with a cooling water temperature of 18°C ​​to obtain a dispersion. The glass beads were removed from this dispersion using a mesh (mesh opening: 150 μm). A surface roughening agent was added to the dispersion after removing the glass beads, at a concentration of 10% by mass relative to the total mass of the metal oxide particles and binder resin. Silicone resin particles (trade name: Tospearl 120, manufactured by Momentive Performance Materials, Inc., average particle size: 2 μm) were used as the surface roughening agent. Silicone oil (trade name: SH28PA, manufactured by Dow Corning Toray Co., Ltd.) was added as a leveling agent to the dispersion at a concentration of 0.01% by mass relative to the total mass of the metal oxide particles and binder resin in the dispersion and stirred. This resulted in the preparation of coating solution 2 for the conductive layer.

[0076] <Preparation of Coating Solution 3 for Conductive Layer> The following materials were prepared: Carbon black (product name: VXC72, manufactured by Cabot Corporation) 10 parts 47 parts of blocked isocyanate (product name: Sumidur BL3175, manufactured by Sumitomo Bayer Urethane) 81 parts butyral resin (product name: S-LEC BM-1, manufactured by Sekisui Chemical Co., Ltd.) 90 parts methyl ethyl ketone These were mixed to obtain a dispersion. 38 parts of this dispersion and 30 parts of methyl ethyl ketone were mixed and dispersed in a vertical sand mill using glass beads with a diameter of 1.0 mm for 90 minutes. After removing the glass beads, 0.05 parts of dioctyltin dilaurate was added as a catalyst to the dispersion to prepare coating solution 3 for conductive layer.

[0077] <Preparation of Coating Solution 1 for Undercoat Layer> One hundred parts of rutile-type titanium dioxide particles (average primary particle size: 50 nm, manufactured by Teika) were mixed with 400 parts of methanol and 100 parts of methyl ethyl ketone, and 3.5 parts of vinyltrimethoxysilane was added. The mixture was then dispersed in a vertical sand mill using 1.0 mm diameter glass beads for 8 hours. After removing the glass beads, the methanol and methyl ethyl ketone were distilled off under reduced pressure, and the mixture was dried at 120°C for 3 hours to obtain rutile-type titanium dioxide particles surface-treated with an organosilicon compound. Next, the following materials were prepared: 18.0 parts of rutile-type titanium dioxide particles surface-treated with the organosilicon compound obtained above 4.5 parts N-methoxymethylated nylon (Torezin EF-30T, manufactured by Nagase ChemteX) 1.5 parts copolymer nylon resin (product name: Amilan CM8000, manufactured by Toray) These were added to a mixed solvent of 90 parts of methanol and 60 parts of 1-butanol to prepare a dispersion, which was then dispersed in a vertical sand mill using glass beads with a diameter of 1.0 mm for 5 hours, and the glass beads were removed to prepare coating solution 1 for undercoat layer.

[0078] <Preparation of Coating Solution 2 for Undercoat Layer> In preparing Coating Solution 1 for Undercoat Layer, the amount of vinyltrimethoxysilane used in producing the rutile-type titanium dioxide particles surface-treated with an organosilicon compound was changed from 3.5 parts to 1.8 parts. Otherwise, Coating Solution 2 for Undercoat Layer was prepared in the same manner as Coating Solution 1 for Undercoat Layer.

[0079] <Preparation of Coating Solution 3 for Undercoat Layer> In preparing Coating Solution 1 for Undercoat Layer, the amount of vinyltrimethoxysilane used in producing the rutile-type titanium dioxide particles surface-treated with an organosilicon compound was changed from 3.5 parts to 2.0 parts. Otherwise, Coating Solution 3 for Undercoat Layer was prepared in the same manner as Coating Solution 1 for Undercoat Layer.

[0080] <Preparation of Coating Solution 4 for Undercoat Layer> In preparing Coating Solution 1 for Undercoat Layer, the amount of vinyltrimethoxysilane used in producing the rutile-type titanium dioxide particles surface-treated with an organosilicon compound was changed from 3.5 parts to 3.0 parts. Otherwise, Coating Solution 4 for Undercoat Layer was prepared in the same manner as Coating Solution 1 for Undercoat Layer.

[0081] <Preparation of Coating Solution 5 for Undercoat Layer> In preparing Coating Solution 1 for Undercoat Layer, the amount of vinyltrimethoxysilane used in producing the rutile-type titanium dioxide particles surface-treated with an organosilicon compound was changed from 3.5 parts to 5.0 parts. Otherwise, Coating Solution 5 for Undercoat Layer was prepared in the same manner as Coating Solution 1 for Undercoat Layer.

[0082] <Preparation of Coating Solution 6 for Undercoat Layer> Coating solution 6 for undercoat layer was prepared in the same manner as in preparation of coating solution 1 for undercoat layer, except that the method for preparing rutile-type titanium oxide particles that had been surface-treated with an organosilicon compound was changed as follows. 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 6.0 parts of n-propyltrimethoxysilane was added, followed by stirring for 8 hours with a stirrer. The toluene was then removed by vacuum distillation, and the mixture was dried at 120°C for 3 hours to obtain rutile-type titanium dioxide particles surface-treated with an organosilicon compound.

[0083] <Preparation of Coating Solution 7 for Undercoat Layer> 100 parts of rutile-type titanium dioxide particles (average primary particle size: 15 nm, manufactured by Teika) were mixed with 500 parts of toluene and stirred, and 10.0 parts of isobutyltrimethoxysilane was added, followed by stirring for 8 hours with a stirrer. The toluene was then removed by vacuum distillation, and the mixture was dried at 120°C for 3 hours to obtain rutile-type titanium dioxide particles surface-treated with an organosilicon compound. Next, the following materials were prepared: 12.0 parts of rutile-type titanium dioxide particles that have been surface-treated with the organosilicon compound obtained above 6.0 parts N-methoxymethylated nylon (Torezin EF-30T, manufactured by Nagase ChemteX) 3.0 parts copolymer nylon resin (product name: Amilan CM8000, manufactured by Toray) These were added to a mixed solvent of 90 parts of methanol and 60 parts of 1-butanol to prepare a dispersion, which was then dispersed in a vertical sand mill using glass beads with a diameter of 1.0 mm for 5 hours, and the glass beads were removed to prepare Coating Solution 7 for undercoat layer.

[0084] <Preparation of Coating Solution 8 for Undercoat Layer> In preparing Coating Solution 7 for Undercoat Layer, the amount of isobutyltrimethoxysilane used in producing the rutile-type titanium dioxide particles surface-treated with an organosilicon compound was changed from 10.0 parts to 12.0 parts. Otherwise, Coating Solution 8 for Undercoat Layer was prepared in the same manner as Coating Solution 7 for Undercoat Layer.

[0085] <Preparation of Coating Solution 9 for Undercoat Layer> In preparing Coating Solution 7 for Undercoat Layer, the amount of isobutyltrimethoxysilane used in producing the rutile-type titanium dioxide particles surface-treated with an organosilicon compound was changed from 10.0 parts to 14.0 parts. Otherwise, Coating Solution 9 for Undercoat Layer was prepared in the same manner as Coating Solution 7 for Undercoat Layer.

[0086] <Preparation of Coating Solution 10 for Undercoat Layer> One hundred parts of rutile-type titanium dioxide particles (average primary particle diameter: 40 nm, manufactured by Ishihara Sangyo Kaisha) were mixed with 400 parts of methanol and 100 parts of methyl ethyl ketone, and 3 parts of methyldimethoxysilane was added. The mixture was then dispersed in a vertical sand mill using glass beads with a diameter of 1.0 mm for 8 hours. After removing the glass beads, the methanol and methyl ethyl ketone were distilled off under reduced pressure, and the mixture was dried at 120°C for 3 hours to obtain rutile-type titanium dioxide particles surface-treated with an organosilicon compound. Next, the following materials were prepared: 15.0 parts of rutile-type titanium dioxide particles that have been surface-treated with the organosilicon compound obtained above 5.0 parts of copolymer polyamide having a molar ratio of ε-caprolactam / bis(4-amino-3-methylcyclohexyl)methane / hexamethylenediamine / decamethylenedicarboxylic acid / octadecamethylenedicarboxylic acid of 60% / 15% / 5% / 15% / 5% These were added to a mixed solvent of 56 parts of methanol, 8 parts of 1-propanol, and 16 parts of toluene to prepare a dispersion, which was then dispersed in a vertical sand mill using glass beads with a diameter of 1.0 mm for 5 hours, and the glass beads were removed to prepare coating solution 10 for undercoat layer.

[0087] <Preparation of Coating Solution 11 for Undercoat Layer> A dispersion was prepared by adding 7 parts by weight of titanium oxide particles (average primary particle size: 20 nm, manufactured by Ishihara Sangyo Kaisha: TTO55A) and 13 parts by weight of copolymer nylon (manufactured by Toray Industries, Inc.: CM8000) to a mixed solvent of 159 parts by weight of methyl alcohol and 106 parts by weight of 1,3-dioxolane. This dispersion was dispersed for 8 hours in a vertical sand mill using glass beads with a diameter of 1.0 mm, and the glass beads were removed to prepare coating solution 11 for the undercoat layer.

[0088] <Preparation of Coating Solution 12 for Undercoat Layer> 4.5 parts of N-methoxymethylated nylon (trade name: Toresin EF-30T, manufactured by Nagase ChemteX) and 1.5 parts of copolymer nylon resin (trade name: Amilan CM8000, manufactured by Toray Industries) were added to a mixed solvent of 90 parts of methanol and 45 parts of 1-butanol, followed by stirring at 40°C for 2 hours to prepare undercoat layer coating solution 12.

[0089] <Preparation of Coating Solution 1 for Charge Generating Layer> 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. The mixture was then cooled to 50°C, and the precipitated crystals were filtered off to obtain a dichlorotitanium phthalocyanine paste. The resulting paste was then washed with 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 oxytitanium 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 oxytitanium phthalocyanine pigment. 4.0 g of this amorphous oxytitanium 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 oxytitanium phthalocyanine pigment. 0.5 parts of the oxytitanium phthalocyanine pigment obtained above was mixed with 10 parts of tetrahydrofuran, and 15 parts of 0.9 mm diameter glass beads were added. The mixture was milled in a ball mill at room temperature (23°C) for 1,200 hours. A standard bottle (product name: PS-6, manufactured by Kakuyo Glass Co., Ltd.) was used, and the milling was carried out at 120 revolutions per minute. The resulting solution was filtered through a filter (product number: N-NO.125T, pore size: 133 μm, manufactured by NBC Meshtec Co., Ltd.) to remove the glass beads. 30 parts of tetrahydrofuran was added to the filtered solution, which was then further filtered. The residue on the filter was thoroughly washed with methanol and water. The washed residue was then vacuum dried to obtain 0.44 parts of oxytitanium phthalocyanine pigment. The obtained pigment had a peak at a Bragg angle 2θ of 27.2°±0.2° in the X-ray diffraction spectrum using CuKα radiation. Next, the following materials were prepared: 14 parts of the oxytitanium phthalocyanine pigment obtained by the above milling process 7 parts polyvinyl butyral (product name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.) 139 parts cyclohexanone 354 pieces of 0.9mm diameter glass beads These were dispersed using a sand mill (K-800, manufactured by Igarashi Machinery Manufacturing (now Imex), disk diameter 70 mm, number of disks: 5) for 4 hours at a cooling water temperature of 18°C. The disks were rotated at 1,800 revolutions per minute. 326 parts of cyclohexanone and 465 parts of ethyl acetate were added to this dispersion to prepare Coating Solution 1 for the charge generating layer.

[0090] <Preparation of Coating Solution 2 for Charge Generating Layer> Under a nitrogen flow atmosphere, 5.46 parts of orthophthalonitrile and 45 parts of α-chloronaphthalene were added to a reactor, which was then heated to 30°C and maintained at that temperature. Next, 3.75 parts of gallium trichloride were added at this temperature (30°C). The water concentration of the mixed solution at the time of addition was 150 ppm. The temperature was then increased to 200°C. Next, under a nitrogen flow atmosphere, the mixture was reacted at 200°C for 4.5 hours, then cooled, and the product was filtered when the temperature reached 150°C. The resulting residue was dispersed and washed using N,N-dimethylformamide at 140°C for 2 hours, followed by filtration. The resulting residue was washed with methanol and dried, yielding a chlorogallium phthalocyanine pigment in a 71% yield. 4.65 parts of the chlorogallium phthalocyanine pigment obtained above was dissolved in 139.5 parts of concentrated sulfuric acid at a temperature of 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 (filtered residue) was dispersed and washed with 2% aqueous ammonia for 30 minutes, and then filtered using a filter press. The resulting wet cake (filtered residue) was then dispersed and washed with ion-exchanged water, and then filtered three times using a filter press. Finally, the solution was freeze-dried to obtain a hydroxygallium phthalocyanine pigment (hydrated hydroxygallium phthalocyanine pigment) with a solids content of 23% in a yield of 97%.

[0091] 6.6 kg of the above hydroxygallium phthalocyanine pigment was dried using a Hyper Dry dryer (trade name: HD-06R, frequency (oscillation frequency): 2455 MHz±15 MHz, manufactured by Nippon Biocon) as follows. The hydroxygallium phthalocyanine pigment was placed on a dedicated circular plastic tray in the form of a lump (a wet cake thickness of 4 cm or less) as it was removed from the filter press, and the far infrared rays were turned off, with the temperature of the inner wall of the dryer set to 50° C. During microwave irradiation, the vacuum pump and leak valve were adjusted to adjust the degree of vacuum to 4.0 to 10.0 kPa. In the first step, a 4.8 kW microwave was applied to the hydroxygallium phthalocyanine pigment for 50 minutes, and then the microwave was turned off and the leak valve was closed to create a high vacuum of 2 kPa or less. At this point, the solid content of the hydroxygallium phthalocyanine pigment was 88%. In the second step, the leak valve was adjusted to adjust the degree of vacuum (pressure inside the dryer) to within the above-mentioned set value (4.0 to 10.0 kPa). The hydroxygallium phthalocyanine pigment was then irradiated with 1.2 kW microwaves for 5 minutes, and the microwaves were then temporarily turned off and the leak valve was closed to create a high vacuum of 2 kPa or less. This second step was repeated once more (twice in total). At this point, the solids content of the hydroxygallium phthalocyanine pigment was 98%. Furthermore, in the third step, microwave irradiation was carried out in the same manner as in the second step, except that the microwave output was changed from 1.2 kW to 0.8 kW in the second step. This third step was repeated once more (twice in total). In the fourth step, the leak valve was adjusted to restore the vacuum (pressure inside the dryer) to the set value (4.0 to 10.0 kPa). The hydroxygallium phthalocyanine pigment was then irradiated with 0.4 kW microwaves for 3 minutes, and the microwaves were then turned off and the leak valve was closed to create a high vacuum of 2 kPa or less. This fourth step was repeated seven more times (a total of eight times). Over a total of three hours, 1.52 kg of hydroxygallium phthalocyanine pigment (crystal) with a water content of 1% or less was obtained.

[0092] Next, the following materials were prepared: 0.5 parts of the hydroxygallium phthalocyanine pigment (crystal) obtained above 9.5 parts N-methylformamide (product code: F0059, manufactured by Tokyo Chemical Industry Co., Ltd.) 15 pieces of 0.9mm diameter glass beads These were milled in a ball mill at room temperature (23°C) for 1,200 hours. A standard bottle (product name: PS-6, manufactured by Kakuyo Glass) was used, and the milling was carried out at 120 rotations per minute. The milled liquid 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 N-methylformamide was added to the liquid, followed by filtration. The residue on the filter was thoroughly washed with tetrahydrofuran. The washed residue was then vacuum dried to obtain 0.46 parts of hydroxygallium phthalocyanine pigment. In the X-ray diffraction spectrum using CuKα radiation, the obtained hydroxygallium phthalocyanine 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°. Also, 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 1.9 mass % relative to the content of hydroxygallium phthalocyanine. Next, the following materials were prepared: 20 parts of the hydroxygallium phthalocyanine pigment obtained by the above milling process 10 parts polyvinyl butyral (product name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.) 190 parts cyclohexanone 482 pieces of 0.9mm diameter glass beads These were dispersed using a sand mill (K-800, manufactured by Igarashi Machinery Manufacturing (now Imex), disk diameter 70 mm, number of disks 5) for 4 hours at a cooling water temperature of 18°C. The disks were rotated at 1,800 revolutions per minute. 444 parts of cyclohexanone and 634 parts of ethyl acetate were added to this dispersion to prepare coating solution 2 for the charge generating layer.

[0093] <Coating liquid for charge transport layer 1> The following materials were prepared: 5 parts of a triarylamine compound represented by the following formula (CTM-1) as a charge transport material 5 parts of a triarylamine compound represented by the following formula (CTM-2) 10 parts polycarbonate (product name: Iupilon Z-400, manufactured by Mitsubishi Engineering Plastics) [ka] [ka] These were dissolved in a mixed solvent of 25 parts of orthoxylene / 25 parts of methyl benzoate / 25 parts of dimethoxymethane to prepare a coating solution 1 for the charge transport layer.

[0094] <Coating liquid for charge transport layer 2> The following materials were prepared: 10 parts of an enamine compound represented by the following formula (CTM-3) as a charge transport material 10 parts polycarbonate (product name: Iupilon Z-400, manufactured by Mitsubishi Engineering Plastics) [ka] These were dissolved in a mixed solvent of 60 parts tetrahydrofuran and 15 parts toluene to prepare a coating solution 2 for the charge transport layer.

[0095] <Coating liquid for charge transport layer 3> In the preparation of Coating Solution 2 for Charge Transport Layer, 10 parts of the enamine compound represented by the following Formula (CTM-4) was used instead of 10 parts of the enamine compound represented by Formula (CTM-3). Otherwise, Coating Solution 3 for Charge Transport Layer was prepared in the same manner as Coating Solution 2 for Charge Transport Layer. [ka]

[0096] <Coating liquid for charge transport layer 4> In the preparation of Coating Solution 2 for Charge Transport Layer, 10 parts of a triarylamine compound represented by the following Formula (CTM-5) was used instead of 10 parts of the enamine compound represented by Formula (CTM-3). Otherwise, Coating Solution 4 for Charge Transport Layer was prepared in the same manner as Coating Solution 2 for Charge Transport Layer. [ka]

[0097] <Coating liquid for charge transport layer 5> In the preparation of Coating Solution 1 for Charge Transport Layer, the amount of the triarylamine compound represented by Formula (CTM-1) used was changed from 5 parts to 6 parts, and the amount of the triarylamine compound represented by Formula (CTM-2) used was changed from 5 parts to 6 parts. Otherwise, Coating Solution 5 for Charge Transport Layer was prepared in the same manner as Coating Solution 1 for Charge Transport Layer.

[0098] <Coating liquid for charge transport layer 6> In the preparation of Coating Solution 1 for Charge Transport Layer, the amount of the triarylamine compound represented by Formula (CTM-1) used was changed from 5 parts to 6.5 parts, and the amount of the triarylamine compound represented by Formula (CTM-2) used was changed from 5 parts to 6.5 parts. Otherwise, Coating Solution 6 for Charge Transport Layer was prepared in the same manner as Coating Solution 1 for Charge Transport Layer.

[0099] <Coating liquid for charge transport layer 7> In the preparation of Coating Solution 1 for Charge Transport Layer, the amount of the triarylamine compound represented by Formula (CTM-1) used was changed from 5 parts to 8 parts, and the amount of the triarylamine compound represented by Formula (CTM-2) used was changed from 5 parts to 8 parts. Otherwise, Coating Solution 7 for Charge Transport Layer was prepared in the same manner as Coating Solution 1 for Charge Transport Layer.

[0100] <Coating liquid for charge transport layer 8> In the preparation of Coating Solution 2 for Charge Transport Layer, 10 parts of the compound represented by the following Formula (CTM-6) were used instead of 10 parts of the enamine compound represented by Formula (CTM-3). Otherwise, Coating Solution 8 for Charge Transport Layer was prepared in the same manner as Coating Solution 2 for Charge Transport Layer. [ka]

[0101] <Coating liquid for charge transport layer 9> In the preparation of Coating Solution 2 for Charge Transport Layer, 10 parts of the compound represented by the following Formula (CTM-7) were used instead of 10 parts of the enamine compound represented by Formula (CTM-3). Otherwise, Coating Solution 9 for Charge Transport Layer was prepared in the same manner as Coating Solution 2 for Charge Transport Layer. [ka]

[0102] <Coating liquid for charge transport layer 10> In the preparation of Coating Solution 8 for Charge Transport Layer, the amount of the compound represented by Formula (CTM-6) used was changed from 10 parts to 16 parts. Otherwise, Coating Solution 10 for Charge Transport Layer was prepared in the same manner as Coating Solution 8 for Charge Transport Layer.

[0103] <Protective layer coating solution 1> 24 parts of a compound represented by the following formula (4-1) and 0.1 parts of a siloxane-modified acrylic compound (Simac US270, manufactured by Toagosei Co., Ltd.) were mixed with a mixed solvent of 42 parts of cyclohexane and 18 parts of 1-propanol and stirred to prepare coating solution 1 for the protective layer. [ka]

[0104] <Production of electrophotographic photoreceptors> [Example 1] <Support> An aluminum cylinder having a diameter of 24 mm and a length of 257 mm was used as the support (cylindrical support). <Conductive layer> The conductive layer coating liquid 1 was dip-coated onto the above support to form a coating film, and the coating film was heated at 150° C. for 30 minutes to be cured, thereby forming a conductive layer with a film thickness of 25 μm. <Undercoat layer> The undercoat layer coating solution 1 was dip-coated onto the conductive layer to form a coating film, and the coating film was cured by heating at 100° C. for 10 minutes to form an undercoat layer with a thickness of 1.7 μm. <Charge generation layer> The undercoat layer was dip-coated with the charge generating layer coating solution 1 to form a coating film, and the coating film was dried by heating at a temperature of 100° C. for 10 minutes to form a charge generating layer having a thickness of 0.20 μm. <Charge transport layer> The charge transport layer coating solution 1 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 15 μm. <Protective layer> The protective layer coating solution 1 was dip-coated onto the charge transport layer to form a coating film, which was then dried at 35°C for 4 minutes. The coating film was then irradiated with an electron beam for 4.8 seconds under a nitrogen atmosphere at an acceleration voltage of 57 kV and a beam current of 5.3 mA. The distance between the support (irradiated object) and the electron beam irradiation window was 25 mm, and the support (irradiated object) was rotated at a speed of 300 rpm. The electron beam absorbed dose was measured and found to be 20 kGy. The coating film was then heated in a nitrogen atmosphere from 25°C to 137°C over 10 seconds. The oxygen concentration between electron beam irradiation and subsequent heat treatment was 10 ppm or less. The coating film was then naturally cooled in the atmosphere to 25°C, and then heat-treated for 10 minutes at 100°C to form a protective layer with a thickness of 1.9 μm.

[0105] [Examples 2 to 62] In Example 1, the type of coating liquid for the conductive layer and the thickness of the conductive layer, the type of coating liquid for the undercoat layer and the thickness of the undercoat layer, the type of coating liquid for the charge generation layer and the thickness of the charge generation layer, and the type of coating liquid for the charge transport layer and the thickness of the charge transport layer were changed as shown in Table 1. Otherwise, electrophotographic photoreceptors according to Examples 2 to 62 were produced in the same manner as in Example 1. However, in Examples 43 to 50 and 59 to 60, no conductive layer was formed, and an undercoat layer was formed on the support, and in Examples 3 to 60, no protective layer was formed.

[0106] [Comparative Examples 1 to 10] In Example 1, the type of coating liquid for the undercoat layer and the thickness of the undercoat layer, the type of coating liquid for the charge generation layer and the thickness of the charge generation layer, and the type of coating liquid for the charge transport layer and the thickness of the charge transport layer were changed as shown in Table 2. Otherwise, electrophotographic photoreceptors according to Comparative Examples 1 to 10 were produced in the same manner as in Example 1. However, in Comparative Examples 1 to 10, no conductive layer was formed, and an undercoat layer was formed on the support, but no protective layer was formed.

[0107] [Comparative Example 11] <Support> The surface of an aluminum cylinder with a diameter of 24 mm and a length of 257 mm was anodized, and then sealed with a sealing agent whose main component was nickel acetate, forming an anodized coating with a thickness of 6.0 μm, which was used as a support (cylindrical support). <Charge generation layer> The charge generating layer coating liquid 1 was dip coated onto the support obtained above 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 generating layer with a film thickness of 0.40 μm. <Charge transport layer> The following materials were prepared: 5 parts of a compound represented by the following formula (CTM-8) as a charge transport material 10 parts of polycarbonate (viscosity average molecular weight: approximately 30,000) having a repeating structure represented by the following formula (B-1): [ka] [ka] These were dissolved in a mixed solvent of 50 parts tetrahydrofuran and 15 parts toluene to prepare a coating liquid for the charge transport layer. The charge transport layer coating liquid prepared above was dip coated onto the charge generation layer formed above to form a coating film, and the coating film was heated and dried at a temperature of 120°C for 30 minutes to form a charge transport layer with a thickness of 18 μm.

[0108] [Comparative Example 12] <Support> An aluminum cylinder having a diameter of 24 mm and a length of 257 mm was used as the support (cylindrical support). <Undercoat layer> The following materials were prepared: 20 parts acetylacetone zirconium butoxide γ-aminopropylethoxysilane 2 parts 1.5 parts polyvinyl butyral resin (product name: S-LEC BM-S, manufactured by Sekisui Chemical) These were dissolved in 70 parts of n-butyl alcohol to prepare a coating solution for the undercoat layer. The above-prepared coating solution for the undercoat layer was dip-coated onto the above-prepared support to form a coating film, and the coating film was dried by heating at a temperature of 150°C for 10 minutes to form an undercoat layer with a thickness of 0.9 µm. <Charge generation layer> Five parts of X-type metal-free phthalocyanine, five parts of vinyl chloride-vinyl acetate copolymer (product name: VMCH, manufactured by Union Carbide), and 200 parts of n-butyl acetate were dispersed in a vertical sand mill using 1.0 mm diameter glass beads for two hours. The glass beads were then removed to prepare a charge generation layer coating solution. This charge generation layer coating solution was dip-coated onto the undercoat layer formed above, and the resulting coating was dried at 100°C for 10 minutes to form a charge generation layer with a thickness of 0.20 μm. <Charge transport layer> The charge transport layer coating liquid 8 was dip coated onto the charge generation layer formed above 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 24 μm.

[0109] [Comparative Example 13] <Support> An aluminum cylinder having a diameter of 24 mm and a length of 257 mm was used as the support (cylindrical support). <Undercoat layer> A mixed powder of 50 parts titanium dioxide particles (average primary particle size: 25 nm, manufactured by Nippon Aerosil Co., Ltd.: P25) and 50 parts titanium dioxide particles (average primary particle size: 300 nm, manufactured by Fuji Titanium Industries Co., Ltd.: TAF-300J) was prepared. The surface of this mixed powder was mechanochemically treated with 5 parts of γ-aminopropyltriethoxysilane via a gas-phase process, bonded to the surface, and then washed with pure water and dried. The resulting product was then dispersed in a mixed solvent of 200 parts methanol, 500 parts methylene chloride, and 200 parts butanol with 50 parts copolymer nylon resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) to prepare a coating solution for the undercoat layer. The above-prepared coating solution for the undercoat layer was dip-coated onto the above-prepared support, and the resulting coating film was dried at 140° C. for 20 minutes to form an undercoat layer with a thickness of 1.5 μm. <Charge generation layer> The coating liquid 1 for the charge generating layer was dip-coated onto the undercoat layer formed above 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 generating layer with a film thickness of 0.30 μm. <Charge transport layer> The following materials were prepared: 10 parts of a compound represented by the following formula (CTM-9) as a charge transport material 10 parts of polycarbonate (viscosity average molecular weight: approximately 30,000) having a repeating structure represented by the following formula (B-2): [ka] [ka] These were dissolved in 100 parts of dichloromethane to prepare a coating solution for the charge transport layer. The charge transport layer coating liquid prepared above was dip-coated onto the charge generation layer formed above to form a coating film, and the coating film was heated and dried at a temperature of 120°C for 30 minutes to form a charge transport layer with a thickness of 20 μm.

[0110] [Comparative Example 14] <Support> An aluminum cylinder having a diameter of 24 mm and a length of 257 mm was used as the support (cylindrical support). <Undercoat layer> 100 parts of zinc oxide particles (average primary particle size: 70 nm, manufactured by Teika, specific surface area: 15 m / g) and 500 parts of methanol were mixed by stirring, and 1.25 parts by mass of a silane coupling agent (trade name: KBM603, manufactured by Shin-Etsu Chemical Co., Ltd.) was added and stirred for 2 hours. Thereafter, the methanol was distilled off under reduced pressure, and the particles were dried at 120°C for 3 hours to obtain zinc oxide particles surface-treated with an organosilicon compound. Next, the following materials were prepared: 60 parts of zinc oxide particles that have been surface-treated with the organosilicon compound obtained above 0.6 parts Alizarin 13.5 parts blocked isocyanate (product name: Sumidur 3173, manufactured by Sumitomo Bayer Urethane) 15 parts butyral resin (product name: BM-1, manufactured by Sekisui Chemical) A dispersion was prepared by mixing 38 parts of a solution prepared by dissolving these compounds in 85 parts of methyl ethyl ketone with 25 parts of methyl ethyl ketone. This dispersion was dispersed for 4 hours in a vertical sand mill using 1.0 mm diameter glass beads, and the glass beads were removed. Subsequently, 0.005 parts of dioctyltin dilaurate as a catalyst and 4 parts of silicone resin particles (Tospearl 145, manufactured by GE Toshiba Silicones) were added to prepare a coating solution for the undercoat layer. The above-prepared coating solution for undercoat layer was dip-coated onto the above-prepared support, and the resulting coating film was dried at 180° C. for 40 minutes to form an undercoat layer with a thickness of 25 μm. <Charge generation layer> The following materials were prepared: 15 parts of chlorogallium phthalocyanine crystals having strong diffraction peaks at Bragg angles 2θ of at least 7.4°, 16.6°, 25.5°, and 28.3° in an X-ray diffraction spectrum using CuKα radiation as a charge generating material 10 parts vinyl chloride-vinyl acetate copolymer resin (product name: VMCH, manufactured by Nippon Union Carbide) 300 parts n-butyl alcohol The mixture was dispersed for 4 hours in a vertical sand mill using glass beads with a diameter of 1.0 mm, and the glass beads were removed to prepare a coating liquid for the charge generating layer. The charge generating layer coating liquid prepared above was dip coated onto the 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 generating layer with a thickness of 0.20 μm. <Charge transport layer> 0.6 parts of tetrafluoroethylene resin particles (average particle size: 0.2 μm) and 0.015 parts of a fluorinated alkyl group-containing methacrylic copolymer (weight average molecular weight: 30,000) were dispersed in a mixed solvent of 4 parts tetrahydrofuran and 1 part toluene. The mixture was then stirred and mixed for 48 hours while maintaining the liquid temperature at 20°C, to obtain a tetrafluoroethylene resin particle suspension. Next, the following materials were prepared: 6 parts of polycarbonate (viscosity average molecular weight: approximately 55,000) having a repeating structure represented by the following formula (B-3): Two parts of a compound represented by the following formula (CTM-10) as a charge transport material 0.1 parts of 2,6-di-t-butyl-4-methylphenol as an antioxidant [ka] [ka] These were mixed and dissolved in a mixed solvent of 24 parts tetrahydrofuran and 11 parts toluene. The tetrafluoroethylene resin particle suspension obtained above was added to this and stirred to form a suspension, which was then dispersed six times using a high-pressure homogenizer (Yoshida Kikai Kogyo) equipped with a through-type chamber with fine flow channels, at a pressure of 500 kgf / cm2. Five ppm of fluorine-modified silicone oil (product name: FL-100, Shin-Etsu Silicone) was added to the resulting solution, which was then thoroughly stirred to obtain a coating solution for forming a charge transport layer. The charge transport layer coating liquid prepared above was dip coated onto the charge generation layer formed above to form a coating film, and the coating film was heated and dried at a temperature of 135°C for 30 minutes to form a charge transport layer with a thickness of 25 μm.

[0111] [Comparative Example 15] <Support> The surface of an aluminum cylinder with a diameter of 24 mm and a length of 257 mm was anodized, and then sealed with a sealing agent whose main component was nickel acetate, forming an anodized coating with a thickness of 7.4 μm, which was used as a support (cylindrical support). <Undercoat layer> A dispersion was prepared by adding 5 parts of titanium oxide particles (average primary particle size: 35 nm, manufactured by Teika: MT-500SA) and 5 parts of copolymer nylon (trade name: Amilan CM8000, manufactured by Toray) to a mixed solvent of 50 parts of methanol and 10 parts of n-propanol. This dispersion was dispersed for 5 hours in a vertical sand mill using 1.0 mm diameter glass beads, and the glass beads were removed to prepare a coating solution for an undercoat layer. The above-prepared coating solution for an undercoat layer was dip-coated onto the above-prepared support, and the resulting coating was dried by heating at 150°C for 10 minutes to form an undercoat layer with a thickness of 1.2 μm. <Charge generation layer> The coating liquid 1 for the charge generating layer was dip-coated onto the undercoat layer formed above 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 generating layer with a film thickness of 0.20 μm. <Charge transport layer> The following materials were prepared: 10 parts of 1,1-bis(4-diethylaminophenyl)-4,4-diphenyl-1,3-butadiene as a charge transport material 10 parts polycarbonate (product name: PCZ-500, manufactured by Mitsubishi Gas Chemical Company) 0.1 parts dibutylhydroxytoluene as antioxidant These were dissolved in 100 parts of tetrahydrofuran to prepare a coating solution for the charge transport layer. The charge transport layer coating liquid prepared above was dip coated onto the charge generation layer formed above to form a coating film, and the coating film was heated and dried at a temperature of 135°C for 30 minutes to form a charge transport layer with a thickness of 36 μm.

[0112] [Comparative Example 16] An electrophotographic photoreceptor according to Comparative Example 16 was produced in the same manner as in Comparative Example 15, except that the method for forming the charge transport layer in Comparative Example 15 was changed as follows. <Charge transport layer> Charge transport layer coating liquid 4 was dip coated onto the charge generating 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 having a thickness of 17 μm.

[0113] [Comparative Example 17] <Support> An aluminum cylinder having a diameter of 24 mm and a length of 257 mm was used as the support (cylindrical support). <Conductive layer> The conductive layer coating solution 2 was dip-coated onto the support to form a coating film, and the coating film was heated at 150° C. for 30 minutes to be cured, thereby forming a conductive layer with a film thickness of 25 μm. <Undercoat layer> The undercoat layer coating solution 1 was dip-coated onto the conductive layer formed above to form a coating film, and the coating film was heated at 100°C for 10 minutes to harden, thereby forming an undercoat layer with a film thickness of 1.7 μm. <Charge generation layer> The following materials were prepared: Ten parts of hydroxygallium phthalocyanine in a crystalline form having diffraction peaks at Bragg angles 2θ of at least 7.5° and 28.4° in an X-ray diffraction spectrum using CuKα radiation as a charge generating material 5 parts polyvinyl butyral resin (product name: S-LEC BX-1, manufactured by Sekisui Chemical Co., Ltd.) These were added to 200 parts of cyclohexanone and dispersed for 6 hours in a sand mill using glass beads with a diameter of 0.9 mm. The mixture was further diluted with 150 parts of cyclohexanone and 350 parts of ethyl acetate to prepare a coating solution for the charge generating layer. The coating liquid for the charge generating layer prepared above was dip-coated onto the undercoat layer formed above, and the resulting coating film was dried at 95°C for 10 minutes to form a charge generating layer with a film thickness of 0.20 μm. <Charge transport layer> The charge transport layer coating liquid 4 was dip coated onto the charge generation layer formed above 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.

[0114] [Comparative Example 18] An electrophotographic photosensitive member according to Comparative Example 18 was produced in the same manner as in Comparative Example 17, except that the thickness of the charge generating layer was changed from 0.20 μm to 0.16 μm.

[0115] [Comparative Example 19] An electrophotographic photoreceptor according to Comparative Example 19 was produced in the same manner as in Comparative Example 17, except that a protective layer was provided on the charge transport layer as follows. <Protective layer> The protective layer coating solution 1 was dip-coated onto the charge transport layer to form a coating film, which was then dried at 35°C for 4 minutes. The coating film was then irradiated with an electron beam for 4.8 seconds under a nitrogen atmosphere at an acceleration voltage of 57 kV and a beam current of 5.3 mA. The distance between the support (irradiated object) and the electron beam irradiation window was 25 mm, and the support (irradiated object) was rotated at a speed of 300 rpm. The electron beam absorbed dose was measured and found to be 20 kGy. The coating film was then heated in a nitrogen atmosphere from 25°C to 137°C over 10 seconds. The oxygen concentration between electron beam irradiation and subsequent heat treatment was 10 ppm or less. The coating film was then naturally cooled in the atmosphere to 25°C, and then heat-treated for 10 minutes at 100°C to form a protective layer with a thickness of 1.9 μm.

[0116] [Comparative Example 20] An electrophotographic photoreceptor according to Comparative Example 20 was produced in the same manner as in Comparative Example 17, except that the method for forming the charge transport layer in Comparative Example 17 was changed as follows. <Charge transport layer> The charge transport layer coating solution 2 was dip coated onto the charge generating 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 having a thickness of 17 μm.

[0117] [Comparative Example 21] An electrophotographic photoreceptor according to Comparative Example 21 was produced in the same manner as in Comparative Example 17, except that the method for forming the charge transport layer in Comparative Example 17 was changed as follows. <Charge transport layer> The charge transport layer coating solution 3 was dip coated onto the charge generating 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 having a thickness of 17 μm.

[0118] [Comparative Example 22] An electrophotographic photoreceptor of Comparative Example 22 was produced in the same manner as in Comparative Example 21, except that a protective layer was formed on the charge transport layer in the following manner. <Protective layer> The protective layer coating solution 1 was dip-coated onto the charge transport layer to form a coating film, which was then dried at 35°C for 4 minutes. The coating film was then irradiated with an electron beam for 4.8 seconds under a nitrogen atmosphere at an acceleration voltage of 57 kV and a beam current of 5.3 mA. The distance between the support (irradiated object) and the electron beam irradiation window was 25 mm, and the support (irradiated object) was rotated at a speed of 300 rpm. The electron beam absorbed dose was measured and found to be 20 kGy. The coating film was then heated in a nitrogen atmosphere from 25°C to 137°C over 10 seconds. The oxygen concentration between electron beam irradiation and subsequent heat treatment was 10 ppm or less. The coating film was then naturally cooled in the atmosphere to 25°C, and then heat-treated for 10 minutes at 100°C to form a protective layer with a thickness of 1.9 μm.

[0119] [Table 1]

[0120] [Table 2]

[0121] [Evaluation of electrophotographic photoreceptors] The electrophotographic photoreceptors according to the above Examples and Comparative Examples were evaluated as follows, and the results are shown in Tables 3 and 4. In Tables 3 and 4, the "film thickness of the layer having charge transport capability" means the combined film thickness of the charge transport layer and the protective layer when the protective layer has charge transport capability, and means the film thickness of the charge transport layer when the protective layer does not have charge transport capability.

[0122] <S0、S1、S2、S3、S4および|ΔV r |Rating> S0, S1, S2, S3, S4 and |ΔV rA photoreceptor testing device (product name: CYNTHIA59, manufactured by Gentec Co., Ltd.) was used for the evaluation. The photoreceptors according to the examples and comparative examples were left in the photoreceptor testing device in an environment of a temperature of 15°C and a relative humidity of 45% RH or a temperature of 45°C and a relative humidity of 16% RH for 24 hours or more, and the evaluation was carried out. An electrically conductive rubber roller with a diameter of 8 mm was used as the charging member. In measuring the potential, a surface potential probe (model 6000B-8, manufactured by Trek Japan Co., Ltd.) was placed at a position 1 mm away from the electrophotographic photosensitive member, and a surface potential meter (model 344, manufactured by Trek Japan Co., Ltd.) was used. Under the above conditions, following the procedure described above, S0, S1, S2, S3, S4 and |ΔV r Calculate |, the value of S1 / S0, the positive and negative values ​​of S2, S3, and S4, and |ΔV r The value of | was evaluated.

[0123] <Image color fluctuations> The electrophotographic device used for evaluation was a modified laser beam printer (product name: HP Color Laser Jet Enterprise M652, manufactured by Hewlett-Packard Co.) The modifications included the ability to adjust the voltage applied to the charging roller and the amount of image exposure light, and the printing speed was set to 100 sheets per minute. First, the electrophotographic device and the photosensitive member were left in an environment of a temperature of 15° C. and a relative humidity of 45% RH for 24 hours or more, and then the photosensitive member was mounted in a cartridge of the electrophotographic device. To evaluate the color variation of images during repeated use, 2,000 sheets (equivalent to 4,000 double-sided sheets) of A4-sized plain paper were printed using a test chart with a printing ratio of 1% in double-sided printing mode. After image printing began, the relative humidity of the environment containing the electrophotographic device and photoreceptor was increased from 45% RH to 80% RH at a rate of 10% RH over 10 minutes. As the charging condition of the photosensitive member, the voltage applied to the charging roller was adjusted so that the initial dark potential was -500V, and as the exposure condition, the amount of light exposure was adjusted so that the initial bright potential was -140V. The surface potential of the photoreceptor was measured by modifying the cartridge and attaching a potential probe (product name: model 6000B-8, manufactured by Trek Japan Co., Ltd.) to the development position. The potential was measured using a surface potentiometer (product name: model 344, manufactured by Trek Japan Co., Ltd.). Before and immediately after the repeated use, one halftone image was printed, and the density of each was measured using a spectrodensitometer (trade name: X-Rite504 / 508, manufactured by X-Rite Corporation), and the absolute value of the color change between the printed images was calculated. An absolute value of 0.15 or less was considered to be the effect of the present invention.

[0124] [Table 3]

[0125] [Table 4] [Explanation of symbols]

[0126] 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

Claims

1. An electrophotographic photoreceptor having a support, an undercoat layer, a charge generating layer, and a charge transport layer in this order, the undercoat layer contains titanium oxide particles that have been surface-treated with an organosilicon compound; When the hydrophobicity of the titanium oxide particles surface-treated with the organosilicon compound is defined as α [%], α [%] is 10% or more and 70% or less, the charge generating layer contains an oxytitanium phthalocyanine pigment or a hydroxygallium phthalocyanine pigment, the charge transport layer contains a triarylamine compound represented by the following formula (CTM-1) and a triarylamine compound represented by the following formula (CTM-2), 【number】 【number】 S obtained by the following procedure (A) ０ , S １ , S ２ , S ３ , and S ４ Regarding S １ / S ０ is 0.34 or less, and S ２ , S ３ , and S ４ one is positive and two are negative, or two are positive and one is negative, The electrophotographic photoreceptor is characterized in that: Procedure (A) A1. Temperature 15°C is T １ [°C], relative humidity 45% RH １ [%RH]. Temperature T １ [℃], relative humidity Φ １ [% RH], each I ｅｘｐ [μJ / cm ２ ]corresponding to V ｅｘｐ Obtain [V]. Procedure (B) While the electrophotographic photosensitive member is rotated at a rotation speed of 60 rpm, the following B1 to B5 are carried out. B1. Set the surface potential to 0. B2. A voltage is applied to the surface of the electrophotographic photosensitive member so that the absolute value of the surface potential becomes 500V. B3. 0.125 seconds after the voltage application is finished, the wavelength is 655 nm and the light intensity is I ｅｘｐ [μJ / cm ２ ] and expose to light. B4. The absolute value of the surface potential measured 0.250 seconds after the end of voltage application is V ｅｘｐ Let it be [V]. B5.I ｅｘｐ to 0.000 μJ / cm ２ to 1.000 μJ / cm ２ up to 0.001 μJ / cm ２ Repeat B1 to B4 while changing the interval ｅｘｐ [μJ / cm ２ ]corresponding to V ｅｘｐ Obtain [V]. A2. Temperature 45℃ ２ [°C], relative humidity 16% RH ２ [%RH]. Temperature T ２ [℃], relative humidity Φ ２ [% RH], each I by procedure (B) ｅｘｐ [μJ / cm ２ ]corresponding to V ｅｘｐ Obtain [V]. A3. V obtained in A1 ｅｘｐ For [V], the vertical axis is V ｅｘｐ [V], horizontal axis is I ｅｘｐ Plot it as I ｅｘｐ =0.000~0.030μJ / cm ２ The gradient k in the range is calculated, and the quantum efficiency η is calculated using the following formula (1). ０ (T １ , Φ １ ) is required. [Equation 1] (In formula (1), e is the elementary charge, d is the film thickness of the photosensitive layer, η ０ is the quantum efficiency, ε ０ is the dielectric constant of a vacuum, ε ｒ is the relative dielectric constant of the charge transport layer, h is Planck's constant, and ν is the frequency of the irradiated light. A4. The graph created in A3 is fitted using the following equation (2) to obtain the temperature T １ [℃], relative humidity Φ １ Recombination constant P in [% RH] ｅ (T １ , Φ １ ), and residual voltage V ｒ (T １ , Φ １ ) is determined. The quantum efficiency during fitting, η ０ The value of is calculated in A3. １ [℃], relative humidity Φ １ V under the condition of [% RH] ｅｘｐ [V] (T １ , Φ １ ) and I ｅｘｐ [μJ / cm ２ ] is obtained according to the following formula (2). [Equation 2] (In formula (2), V ｒ is the remaining power, V ｄ is the absolute value of the surface potential before exposure (500 V), P ｅ is the recombination constant, e is the elementary charge, d is the film thickness of the photosensitive layer, η ０ is the quantum efficiency, ε ０ is the dielectric constant of a vacuum, ε ｒ is the relative dielectric constant of the charge transport layer, h is Planck's constant, and ν is the frequency of the irradiated light. A5. V obtained in A2 ｅｘｐ [V] is determined by the same method as in A3 and A4 above. ２ [℃], relative humidity Φ ２ Quantum efficiency η in [% RH] ０ (T ２ , Φ ２ ), recombination constant P ｅ (T ２ , Φ ２ ), and residual voltage V ｒ (T ２ , Φ ２ ) is calculated. ２ [℃], relative humidity Φ ２ V under the condition of [% RH] ｅｘｐ [V] (T ２ , Φ ２ ) and I ｅｘｐ [μJ / cm ２ ], the relationship according to equation (2) is obtained. A6.V ｅｘｐ [V] (T １ , Φ １ ) to V ｅｘｐ [V] (T ２ , Φ ２ ) is subtracted and the value is ΔV ｅｘｐ Let it be [V]. A7. V obtained in A1 ｅｘｐ Regarding [V], V ｅｘｐ When [V] = 250V, the amount of light is I １／２ [μJ / cm ２ ] and I ｅｘｐ [μJ / cm ２ ]=3.414・I １／２ [μJ / cm ２ ] when V ｅｘｐ [V] to V Ｒ [V]. In this case, V ｅｘｐ [V] (T １ , Φ １ ) for |ΔV ｅｘｐ In the relationship of |[V], V ｅｘｐ [V] (T １ , Φ １ ) is V Ｒ |ΔV when in the range from [V] to 500V ｅｘｐ |The integral value of [V] is S ０ Let's say. A8. In equation (2), quantum efficiency η ０ (T １ , Φ １ ), recombination constant P ｅ (T １ , Φ １ ), and residual voltage V ｒ (T ２ , Φ ２ ) using the value of I ｅｘｐ [μJ / cm ２ ] and V ｅｘｐ Obtain the relationship with [V]. A9.V ｅｘｐ [V] (T １ , Φ １ ) from V obtained in A8 ｅｘｐ The value obtained by subtracting [V] is ΔV ａ Let it be [V]. A10.V ｅｘｐ [V] (T １ , Φ １ ) for |ΔV ａ In the relationship of |[V], V ｅｘｐ [V] (T １ , Φ １ ) is V Ｒ |ΔV when in the range from [V] to 500V ａ |The integral value of [V] is S １ Also, V ｅｘｐ [V] (T １ , Φ １ ) with respect to ΔV ａ In the relationship of [V], V ｅｘｐ [V] (T １ , Φ １ ) is V Ｒ ΔV when in the range from [V] to 500V ａ The integral value of [V] is S ２ Let's say. A11. In formula (2), quantum efficiency η ０ (T ２ , Φ ２ ), recombination constant P ｅ (T １ , Φ １ ), and residual voltage V ｒ (T １ , Φ １ ) using the value of I ｅｘｐ [μJ / cm ２ ] and V ｅｘｐ Obtain the relationship with [V]. A12.V ｅｘｐ [V] (T １ , Φ １ ) from V obtained in A11 ｅｘｐ The value obtained by subtracting [V] is ΔV ｂ Let it be [V]. A13.V ｅｘｐ [V] (T １ , Φ １ ) with respect to ΔV ｂ In the relationship of [V], V ｅｘｐ [V] (T １ , Φ １ ) is V Ｒ ΔV when in the range from [V] to 500V ｂ The integral value of [V] is S ３ Let's say. A14. In equation (2), quantum efficiency η ０ (T １ , Φ １ ), recombination constant P ｅ (T ２ , Φ ２ ), and residual voltage V ｒ (T １ , Φ １ ) using the value of I ｅｘｐ [μJ / cm ２ ] and V ｅｘｐ Obtain the relationship with [V]. A15.V ｅｘｐ [V] (T １ , Φ １ ) from V obtained in A14 ｅｘｐ The value obtained by subtracting [V] is ΔV ｃ Let it be [V]. A16.V ｅｘｐ [V] (T １ , Φ １ ) with respect to ΔV ｃ In the relationship of [V], V ｅｘｐ [V] (T １ , Φ １ ) is V Ｒ ΔV when in the range from [V] to 500V ｃ The integral value of [V] is S ４ Let's say.

2. The S １ / S ０ 2. The electrophotographic photoreceptor according to claim 1, wherein is 0.28 or less.

3. The residual voltage V ｒ (T １ , Φ １ ) and the residual voltage V ｒ (T ２ , Φ ２ ) and the absolute value of the difference |ΔV ｒ When |[V] is set, Applicable | ΔV ｒ | [V] is 20V or less, 3. The electrophotographic photoreceptor according to claim 1.

4. 4. The electrophotographic photoreceptor according to claim 1, wherein the charge transport layer has a thickness of 17 μm or less.

5. the charge generating layer contains the hydroxygallium phthalocyanine pigment, the hydroxygallium phthalocyanine pigment has 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, The crystal particles contain an amide compound represented by the following formula (A1): 【Chemistry 3】 (In the above formula (A1), R 1 represents a methyl group, a propyl group, or a vinyl group.) the content of the amide compound represented by the following formula (A1) contained in the crystal particles is 0.1% by mass or more and 3.0% by mass or less: The electrophotographic photoreceptor according to any one of claims 1 to 4.

6. 6. A process cartridge which integrally supports the electrophotographic photosensitive member according to claim 1 and at least one means selected from the group consisting of a charging means, a developing means, and a cleaning means, and is detachably mountable to a main body of an electrophotographic apparatus.

7. 6. An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1, a charging means, an exposure means, a developing means, and a transfer means.

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