# Patent

## Title
Electrophotographic photosensitive member, process cartridge, and electrophotographic apparatus

## Abstract

A conductive layer contains a binder material, a first particle, and a second particle. The first particle is composed of a core particle and aluminum-doped zinc oxide covering the core particle or is composed of a core particle and oxygen-deficient zinc oxide covering the core particle. The second particle is of the same material as that of the core particle of the first particle. The content of the first particle is 20% by volume or more and 50% by volume or less of the total volume of the conductive layer. The content of the second particle is 0.1% by volume or more and 15% by volume or less of the total volume of the conductive layer and is 0.5% by volume or more and 30% by volume or less of the volume of the first particle.

## Background
BACKGROUND OF THE INVENTION
Field of the Invention
The present invention relates to an electrophotographic photosensitive member, a process cartridge including the electrophotographic photosensitive member, and an electrophotographic apparatus including the electrophotographic photosensitive member.
Description of the Related Art
In recent years, organic photoconductive materials (charge generation materials) have been used in electrophotographic photosensitive members that are loaded on process cartridges or electrophotographic apparatuses. The electrophotographic photosensitive member generally includes a support and a photosensitive layer disposed on the support.
The electrophotographic photosensitive member further includes a conductive layer between the support and the photosensitive layer. The conductive layer contains a metal oxide particle for covering defects on the surface of the support.
Japanese Patent Laid-Open No. 2005-234396 describes a technology for reducing image failure due to current leakage caused by addition of a combined metal oxide particle composed of a particle mainly made of a metal oxide and a surface layer mainly made of zinc oxide, to a conductive layer. The term “current leakage” refers to a phenomenon of an excessive current flow in a local portion of an electrophotographic photosensitive member, resulting from occurrence of electric breakdown at the portion.
Japanese Patent Laid-Open No. 2010-224173 describes a technology for reducing residual potential by using a conductive layer containing a titanium oxide particle covered with zinc oxide.
Unfortunately, the results of investigation by the present inventors demonstrated that in the conductive layer containing a metal oxide particle covered with zinc oxide described in the above-mentioned patent documents, application of a high voltage to the conductive layer in a low-temperature and low-humidity environment readily causes current leakage. It was also demonstrated that the above-described conductive layers are still required to reduce the occurrence of variations in dark portion potential and light portion potential during repetitive use. Occurrence of current leakage prevents the electrophotographic photosensitive member from being sufficiently charged and leads to occurrence of image defects, such as a black spot, a horizontal white streak, and a horizontal black streak, on an output image. The term “horizontal white streak” refers to a white streak occurring on an output image in the direction orthogonal to the rotation direction (circumferential direction) of the electrophotographic photosensitive member, whereas the term “horizontal black streak” refers to a black streak occurring on an output image in the direction orthogonal to the rotation direction (circumferential direction) of the electrophotographic photosensitive member.
SUMMARY OF THE INVENTION
The present invention provides an electrophotographic photosensitive member that can reduce the variations in dark portion potential and light portion potential during repetition use and hardly causes current leakage. The invention further provides a process cartridge and an electrophotographic apparatus each including the electrophotographic photosensitive member.
An aspect of the present invention provides an electrophotographic photosensitive member comprising:
a support;
a conductive layer on the support; and
a photosensitive layer on the conductive layer; wherein
the conductive layer comprises a binder material, a first particle, and a second particle;
the first particle is composed of a core particle coated with aluminum-doped zinc oxide;
the second particle is of the same material as that of the core particle of the first particle;
a content of the first particle in the conductive layer is 20% by volume or more and 50% by volume or less based on a total volume of the conductive layer; and
a content of the second particle in the conductive layer is 0.1% by volume or more and 15% by volume or less based on the total volume of the conductive layer, and 0.5% by volume or more and 30% by volume or less based on the volume of the first particle in the conductive layer.
Another aspect of the present invention provides an electrophotographic photosensitive member comprising:
a support;
a conductive layer on the support; and
a photosensitive layer on the conductive layer; wherein
the conductive layer comprises a binder material, a first particle, and a second particle;
the first particle is composed of a core particle coated with oxygen-deficient zinc oxide;
the second particle is of the same material as that of the core particle of the first particle;
a content of the first particle in the conductive layer is 20% by volume or more and 50% by volume or less based on a total volume of the conductive layer; and
a content of the second particle in the conductive layer is 0.1% by volume or more and 15% by volume or less based on the total volume of the conductive layer, and 0.5% by volume or more and 30% by volume or less based on the volume of the first particle in the conductive layer.
Another aspect of the present invention provides a process cartridge integrally supporting the electrophotographic photosensitive member and at least one device selected from the group consisting of charging devices, developing devices, and cleaning devices and being detachably attachable to an electrophotographic apparatus main body.
Another aspect of the present invention provides an electrophotographic apparatus comprising the electrophotographic photosensitive member and a charging device, an exposing device, a developing device, and a transferring device.
Further features of the present invention will become apparent from the following description of exemplary embodiments with reference to the attached drawings.



BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram schematically illustrating an example of the structure of an electrophotographic apparatus provided with a process cartridge including an electrophotographic photosensitive member.
FIG. 2 is a diagram illustrating an example of a needle breakdown voltage tester.
FIG. 3 is a diagram (top view) for describing a method of measuring the volume resistivity of a conductive layer.
FIG. 4 is a diagram (cross-section view) for describing the method of measuring the volume resistivity of a conductive layer.
FIG. 5 is a diagram for describing a similar knight jump pattern image.



DESCRIPTION OF THE EMBODIMENTS
The electrophotographic photosensitive member of the present invention includes a support, a conductive layer on the support, and a photosensitive layer on the conductive layer.
The photosensitive layer may be a monolayer type photosensitive layer containing a charge generation material and a charge transport material in a single layer or may be a multi-layer type photosensitive layer composed of a charge generating layer containing a charge generation material and a charge transporting layer containing a charge transport material. A multi-layer type photosensitive layer can be especially used in the present invention. The electrophotographic photosensitive member optionally includes an undercoat layer between the conductive layer and the photosensitive layer.
[Support]
The support can be electrically conductive (a conductive support). For example, a metal support made of a metal, such as aluminum, an aluminum alloy, or stainless steel, can be used. A support made of aluminum or an aluminum alloy can be a tube produced by a method including an extrusion step and a drawing step or a tube produced by a method including an extrusion step and an ironing step.
[Conductive Layer]
In the present invention, a conductive layer is disposed on the support in order to cover surface defects of the support. The conductive layer contains a binder material, a first particle, and a second particle.
The first particle is a composite particle composed of a core particle coated with aluminum (Al)-doped zinc oxide (ZnO) or a composite particle composed of a core particle coated with oxygen-deficient zinc oxide (ZnO).
The second particle is of the same material (compound) as that of the core particle of the first particle. For example, when the core particle of the first particle is a titanium oxide particle, the second particle is also made of titanium oxide. When the core particle of the first particle is a tin oxide particle, the second particle is also made of tin oxide. The second particle is not coated with an inorganic material such as zinc oxide, tin oxide, or aluminum oxide, i.e., is not a composite particle, and also is not coated (not surface-treated) with an organic material such as a silane coupling agent. The second particle can be a particle not doped with aluminum.
The content of the first particle in the conductive layer is 20% by volume or more and 50% by volume or less based on the total volume of the conductive layer.
The content of the second particle in the conductive layer is 0.1% by volume or more and 15% by volume or less based on the total volume of the conductive layer and is 0.5% by volume or more and 30% by volume or less of the volume based on the first particle in the conductive layer. The content of the second particle can be 1% by volume or more and 20% by volume or less of the volume based on the first particle.
In the present invention, the conductive layer having a feature described above can reduce the variations in dark portion potential and light portion potential during repetition use and can reduce the occurrence of current leakage. This can be supposed as follows.
If the content of the first particle in the conductive layer is less than 20% by volume based on the total volume of the conductive layer, the distance among individual first particles tends to increase. The increase in the distance among individual first particles tends to raise the volume resistivity of the conductive layer. Consequently, in the image-forming period, charge is prevented from smoothly flowing, residual potential readily increases, and dark portion potential and light portion potential readily vary.
If the content of the first particle in the conductive layer is more than 50% by volume based on the total volume of the conductive layer, the individual first particles tend to be close to one another. A portion in which the individual first particles are close to one another has a locally low volume resistivity in the conductive layer, resulting in a high risk of causing current leakage in the electrophotographic photosensitive member.
Meanwhile, unlike the first particle, the second particle has a roll of reducing the occurrence of current leakage when a high voltage is applied to the electrophotographic photosensitive member in a low-temperature and low-humidity environment.
Typically, charge flowing in the conductive layer mainly flows in the surface of the first particle having a lower powder resistivity than that of the second particle. Since the first particle includes aluminum-doped zinc oxide or oxygen-deficient zinc oxide coating the core particle, the powder resistivity of the first particle is reduced to a level lower than that of the second particle. However, if the electrophotographic photosensitive member is applied with a high voltage such that excessive charge flows in the conductive layer, the charge exceeding the throughput of the surface of the first particle readily causes current leakage in the electrophotographic photosensitive member.
In the conductive layer containing the second particle of the same compound as that of the first particle, charge also flows in the surface of the second particle in addition to the surface of the first particle only when an excessive flow of charge is caused in the conductive layer. If the electrophotographic photosensitive member is applied with a high voltage such that excessive charge flows in the conductive layer, the charge flows also in the surface of the second particle, which allows the charge to more uniformly flow in the conductive layer, resulting in inhibition of current leakage from occurring.
If the content of the second particle in the conductive layer is less than 0.1% by volume based on the total volume of the conductive layer, the effect by the addition of the second particle to the conductive layer is insufficient.
If the content of the second particle in the conductive layer is more than 15% by volume based on the total volume of the conductive layer, the volume resistivity of the conductive layer is readily increased. Consequently, in the image-forming period, charge is prevented from smoothly flowing, residual potential readily increases, and dark portion potential and light portion potential readily vary.
If the content of the second particle in the conductive layer is less than 0.5% by volume based on the volume of the first particle, the effect by the addition of the second particle to the conductive layer is insufficient.
If the content of the second particle in the conductive layer is more than 30% by volume based on the volume of the first particle, the volume resistivity of the conductive layer is readily increased. Consequently, in the image-forming period, charge is prevented from smoothly flowing, residual potential readily increases, and dark portion potential and light portion potential readily vary.
It is supposed that the present invention thus reduces variations in dark portion potential and light portion potential during repetition use and prevents current leakage from occurring.
The surface of the core particle can be coated with zinc oxide by, for example, the method described in Japanese Patent Laid-Open No. 2005-234396.
Examples of the core particle of the first particle include barium sulfate particles and metal oxide particles. Especially, the core particle can be a titanium oxide particle, a zinc oxide particle, or a tin oxide particle.
The second particle may be any particle that is made of the same compound as that of the core particle of the first particle. Examples of the second particle include barium sulfate particles and metal oxide particles. Especially, the second particle can be a titanium oxide particle, a zinc oxide particle, or a tin oxide particle.
The second particle and the core particle of the first particle may be in a granular, spherical, acicular, fibrous, columnar, rod-like, fusiform, tabular, or another similar shape. Among these shapes, spherical particles can be particularly used from the viewpoint of reducing image defects such as black points.
The first particle in the conductive layer can have an average primary particle diameter (D1) of 0.10 μm or more and 0.45 μm or less, in particular, 0.15 μm or more and 0.40 μm or less.
The first particle having an average primary particle diameter of 0.10 μm or more scarcely reaggregates in a conductive layer coating fluid containing the first particle. Consequently, the conductive layer coating fluid has increased stability and forms a conductive layer scarcely causing cracks in its surface.
The first particle having an average primary particle diameter of 0.45 μm or less scarcely roughens the surface of the conductive layer. Consequently, local injection of charge into the photosensitive layer scarcely occurs, and black points are prevented from occurring on a white portion of an output image.
The ratio (D1/D2) of the average primary particle diameter (D1) of the first particle to the average primary particle diameter (D2) of the second particle in the conductive layer can be 0.7 or more and 1.3 or less, in particular, 1.0 or more and 1.3 or less.
If the ratio (D1/D2) is 0.7 or more, the average primary particle diameter of the second particle is not too large compared to that of the first particle, resulting in a further reduction in the variations of dark portion potential and light portion potential. If the ratio (D1/D2) is not higher than 1.3, the average primary particle diameter of the second particle is not too small compared to that of the first particle, resulting in a further reduction in the occurrence of current leakage.
In the present invention, the contents and the average primary particle diameters of the first particle and the second particle in the conductive layer can be determined by three-dimensional structural analysis based on element mapping using a focused ion beam/scanning electron microscope (FIB-SEM) and slice-and-view in FIB-SEM.
The proportion (coverage) of zinc oxide covering (coating) the first particle can be 10% to 60% by mass based on the mass of the first particle. In the present invention, the coverage of zinc oxide on the first particle is determined without considering the mass of aluminum doped in the zinc oxide.
The first particle can have a powder resistivity of 1.0×100 Ω·cm or more and 1.0×106 Ω·cm or less, in particular, 1.0×101 Ω·cm or more and 1.0×105 Ω·cm or less.
The second particle can have a powder resistivity of 1.0×105 Ω·cm or more and 1.0×1010 Ω·cm or less, in particular, 1.0×106 Ω·cm or more and 1.0×109 Ω·cm or less.
The amount (doping rate) of aluminum doped in zinc oxide of the first particle can be 0.1% to 10% by mass based on the mass of zinc oxide. The mass of zinc oxide is that of zinc oxide not including aluminum.
The conductive layer can have a volume resistivity of 1.0×108 Ω·cm or more and 5.0×1012 Ω·cm or less. A volume resistivity of the conductive layer of 5.0×1012 Ω·cm or less allows smooth flow of charge, prevents the residual potential from increasing, and prevents the dark portion potential and the light portion potential from varying, whereas a volume resistivity of the conductive layer of 1.0×108 Ω·cm or more can appropriately control the amount of charge flowing in the conductive layer during the electrophotographic photosensitive member being charged and prevents current leakage from occurring.
A method of measuring the volume resistivity of the conductive layer of an electrophotographic photosensitive member will be described with reference to FIGS. 3 and 4. FIG. 3 is a top view for describing a method of measuring the volume resistivity of a conductive layer. FIG. 4 is a cross-section view for describing the method of measuring the volume resistivity of a conductive layer.
The volume resistivity of a conductive layer is measured in an ordinary temperature and ordinary humidity (23° C./50% RH) environment. Copper tape 203 (manufactured by 3M Japan Limited, Model No. 1181) is attached to a surface of a conductive layer 202 and is used as the electrode on the front surface side of the conductive layer 202. The support 201 is used as the electrode on the back surface side of the conductive layer 202. A power supply 206 for applying a voltage between the copper tape 203 and the support 201 and an ammeter 207 for measuring the current flowing between the copper tape 203 and the support 201 are installed. Copper wire 204 is placed on the copper tape 203 for applying a voltage to the copper tape 203. Copper tape 205, which is the same material as that of the copper tape 203, is attached on the copper wire 204 to fix the copper wire 204 not to protrude from the copper tape 203. The copper tape 203 is applied with a voltage through the copper wire 204.
The value of volume resistivity ρ (Ω·cm) of the conductive layer 202 is defined by the following Expression (1):

ρ=1/(I−I0)×S/d (Ω·cm)  (1)

where I0 represents the background current value (A) when no voltage is applied between the copper tape 203 and the support 201; I represents the current value (A) when only DC voltage (direct current component) of −1 V is applied; d represents the thickness (cm) of the conductive layer 202; and S represents the area S (cm2) of the electrode (copper tape 203) on the front surface side of the conductive layer 202.

In this measurement, minute current values, such as 1×10−6 A or less as the absolute value, are measured. Accordingly, an ammeter that can measure such a minute current is used as the ammeter 207. An example of the ammeter is a pA meter (trade name: 4140B) manufactured by Hewlett-Packard Japan, Ltd.
The volume resistivity measured for a conductive layer prepared by forming only the conductive layer on a support is substantially the same as that measured for a conductive layer prepared by peeling off all layers (photosensitive layer and other layers) above the conductive layer from an electrophotographic photosensitive member.
The powder resistivities of the first particle and the second particle are measured as follows.
The powder resistivities of the first particle and the second particle are measured in an ordinary temperature and ordinary humidity (23° C./50% RH) environment. In the present invention, a resistivity meter (trade name: Roresta GP) manufactured by Mitsubishi Chemical Corporation is used as the measuring apparatus, and a pellet sample is prepared by hardening the first particles or the second particles to be measured with a pressure of 500 kg/cm2. The applied voltage is 100 V.
The conductive layer can be formed by applying a conductive layer coating fluid containing a solvent, a binder material, a first particle, and a second particle onto a support to form a coating film and drying and/or curing the coating film.
The conductive layer coating fluid can be prepared by dispersing the first particle and the second particle in the solvent together with the binder material. The dispersing can be performed by a method using, for example, a paint shaker, a sand mill, a ball mill, or a liquid collision-type high-speed disperser.
Examples of the binder material used for preparing the conductive layer coating fluid include resins such as phenolic resins, polyurethanes, polyamides, polyimides, polyamideimides, polyvinyl acetal, epoxy resins, acrylic resins, melamine resins, and polyesters. These resins may be used alone or in combination. Among these resins, from the viewpoints of inhibiting migration (penetration) to another layer and increasing the dispersibility and dispersion stability of the first particle and the second particle, a curable resin, in particular, a thermosetting resin can be used. In thermosetting resins, in particular, a thermosetting phenolic resin or thermosetting polyurethane can be used. When a curable resin is used as the binder material in the conductive layer, a monomer and/or oligomer of the curable resin is used as the binder material contained in the conductive layer coating fluid.
Examples of the solvent contained in the conductive layer coating fluid include alcohols such as methanol, ethanol, and isopropanol; ketones such as acetone, methyl ethyl ketone, and cyclohexane; ethers such as tetrahydrofuran, dioxane, ethylene glycol monomethyl ether, and propylene glycol monomethyl ether; esters such as methyl acetate and ethyl acetate; and aromatic hydrocarbons such as toluene and xylene.
The conductive layer can have a thickness of 10 μm or more and 40 μm or less, in particular, 15 μm or more and 35 μm or less, from the viewpoint of covering surface defects of the support.
In the present invention, the thicknesses of the layers, including the conductive layer, of the electrophotographic photosensitive member are measured with FISCHERSCOPE MMS manufactured by Fischer Instruments K.K.
In order to inhibit occurrence of interference fringes in an output image due to interference of light reflected on the surface of the conductive layer, the conductive layer may contain a surface roughening material. The surface roughening material can be a resin particle having an average particle diameter of 1 μm or more and 5 μm or less. Examples of the resin particle include particles of curable resins such as curable rubber, polyurethanes, epoxy resins, alkyd resins, phenolic resins, polyesters, silicone resins, and acrylic-melamine resins. Among these resins, a particle of a silicone resin hardly causes aggregation and can be particularly used. Since the resin particle has a small density (0.5 to 2 g/cm3) compared to the density of (4 to 8 g/cm3) of the first particle, the surface of the conductive layer can be efficiently roughened during the formation of the conductive layer. The content of the surface roughening material in the conductive layer can be 1% to 80% by mass of the amount of the binder material in the conductive layer.
The densities (g/cm3) of particles such as the first particle, the second particle, the binder material (if the binder resin is a liquid, the binder material is cured and is then subjected to measurement), and silicone particle are measured with a dry-process automatic densitometer as follows. Particles as a measuring object are pretreated by helium gas purging at a maximum pressure of 19.5 psig for ten times with a dry-process automatic densitometer (trade name: Accupyc 1330) manufactured by Shimadzu Corporation at 23° C. using a container having a capacity of 10 cm3. Subsequently, the internal pressure of the container is equilibrated until the variation in internal pressure becomes 0.0050 psig/min or less, which is a reference value of establishment of equilibrated internal pressure of a sample chamber, and the automatic measurement of the density (g/cm3) is then started. The density of the first particle can be adjusted by means of the amount of zinc oxide covering the core particle or the type of the compound (material) of the core particle. The density of the second particle can be similarly adjusted by means of the type or crystal form of the compound.
The conductive layer may contain a leveling agent for increasing the surface properties of the conductive layer.
[Undercoat Layer]
An undercoat layer having an electrical barrier properties may be disposed between the conductive layer and the photosensitive layer for preventing charge injection from the conductive layer to the photosensitive layer.
The undercoat layer can be formed by applying an undercoat layer coating fluid containing a resin (binder resin) onto the conductive layer to form a coating film and drying the coating film.
Examples of the resin (binder resin) used for the undercoat layer include polyvinyl alcohol, polyvinyl methyl ether, polyacrylic acids, methyl cellulose, ethyl cellulose, polyglutamic acid, casein, polyamides, polyimides, polyamideimides, polyamic acid, melamine resins, epoxy resins, polyurethanes, and polyglutamates. Among these resins, in order to efficiently express the electrical barrier properties of the undercoat layer, a thermoplastic resin can be used. In thermoplastic resins, a thermoplastic polyamide, in particular, copolymer nylon can be used.
The undercoat layer can have a thickness of 0.1 μm or more and 2 μm or less. The undercoat layer may contain an electron transport material (electron receptive material such as acceptor) for allowing smooth flow of charge in the undercoat layer.
Examples of the electron transport material include electron attractive materials, such as 2,4,7-trinitrofluorenone, 2,4,5,7-tetranitrofluorenone, chloranil, and tetracyanoquinodimethane, and polymerized materials of these electron attractive materials.
[Photosensitive Layer]
A photosensitive layer is disposed on the conductive layer or the undercoat layer.
Examples of the charge generation material used for the photosensitive layer includes azo pigments, phthalocyanine pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, squarylium colorants, pyrylium salts, thiapyrylium salts, triphenylmethane colorants, quinacridone pigments, azulenium salt pigments, cyanine dyes, xanthene colorants, quinonimine colorants, and styryl colorants. Among these materials, in particular, a metal phthalocyanine, such as oxytitanium phthalocyanine, hydroxy gallium phthalocyanine, or chlorogalium phthalocyanine, can be used.
When the photosensitive layer is of a multi-layer type, a charge generating layer can be formed by applying a charge generating layer coating fluid to form a coating film and drying the coating film. The charge generating layer coating fluid is prepared by dispersing a charge generation material in a solvent together with a binder resin. The dispersing can be performed by a method using, for example, a homogenizer, ultrasonic waves, a ball mill, a sand mill, an attritor, or a roll mill.
Examples of the binder resin used for the charge generating layer include polycarbonates, polyesters, polyacrylates, butyral resins, polystyrene, polyvinyl acetal, diallylphthalate resins, acrylic resins, methacrylic resins, vinyl acetate resins, phenolic resins, silicone resins, polystyrene, styrene-butadiene copolymers, alkyd resins, epoxy resins, urea resins, and vinyl chloride-vinyl acetate copolymers. These binder resins may be used alone or a mixture or copolymer of two or more thereof.
The mass ratio of the charge generation material and the binder resin (charge generation material: binder resin) can be within a range of 10:1 to 1:10, in particular, 5:1 to 1:1.
Examples of the solvent contained in the charge generating layer coating fluid include alcohols, sulfoxides, ketones, ethers, esters, aliphatic halogenated hydrocarbons, and aromatic compounds.
The charge generating layer can have a thickness of 5 μm or less, in particular, 0.1 μm or more and 2 μm or less.
The charge generating layer can optionally contain various additives such as a sensitizer, an antioxidant, an ultraviolet absorber, and a plasticizer. The charge generating layer may contain an electron transport material (electron receptive material such as acceptor) for allowing smooth flow of charge in the charge generating layer.
The electron transport material contained in the charge generating layer can be the same compound as that in the undercoat layer.
Examples of the charge transport material contained in the photosensitive layer include triarylamine compounds, hydrazone compounds, styryl compounds, stilbene compounds, pyrazoline compounds, oxazole compounds, thiazole compounds, and triallylmethane compounds.
When the photosensitive layer is of a multi-layer type, a charge transporting layer can be formed by preparing a charge transporting layer coating fluid by dissolving a charge transport material and a binder resin in a solvent, applying the charge transporting layer coating fluid to form a coating film, and drying the coating film.
Examples of the binder resin contained in the charge transporting layer include acrylic resins, styrene resins, polyesters, polycarbonates, polyacrylates, polysulfones, polyphenylene oxide, epoxy resins, polyurethane, and alkyd resins. These binder resins may be used alone or a mixture or copolymer of two or more thereof.
The mass ratio of the charge transport material and the binder resin (charge transport material: binder resin) can be within a range of 2:1 to 1:2.
Examples of the solvent contained in the charge transporting layer coating fluid include ketone solvents, ester solvents, ether solvents, aromatic hydrocarbon solvents, and halogen-substituted hydrocarbon solvents.
The charge transporting layer can have a thickness of 3 μm or more and 40 μm or less, in particular, 4 μm or more and 30 μm or less.
The charge transporting layer can optionally contain an antioxidant, an ultraviolet absorber, or a plasticizer.
When the photosensitive layer is of a monolayer type, the monolayer type photosensitive layer can be formed by applying a monolayer type photosensitive layer coating fluid to form a coating film and drying the coating film. The monolayer type photosensitive layer coating fluid contains a charge generation material, a charge transport material, a binder resin, and a solvent. The charge generation material, the charge transport material, the binder resin, and the solvent can be, for example, the same as those mentioned above.
On the photosensitive layer, a protective layer may be disposed for protecting the photosensitive layer.
The protective layer can be formed by applying a protective layer coating fluid containing a resin (binder resin) to form a coating film and drying and/or curing the coating film.
The protective layer can have a thickness of 0.5 μm or more and 10 μm or less, in particular, 1 μm or more and 8 μm or less.
Each of the coating fluids for the above-described layers can be applied by, for example, immersion coating, spray coating, spinner coating, roller coating, Meyer bar coating, or blade coating.
FIG. 1 schematically illustrates an example of the structure of an electrophotographic apparatus provided with a process cartridge including an electrophotographic photosensitive member.
In FIG. 1, the drum-shaped (cylindrical) electrophotographic photosensitive member 1 is rotary-driven around the shaft 2 as the rotation center in the direction indicated by the arrow at a predetermined peripheral velocity.
The surface (peripheral surface) of the electrophotographic photosensitive member 1 that is rotary-driven is uniformly charged to a predetermined positive or negative potential with a charging device (primary charging device, such as a charging roller) 3. Subsequently, the surface is exposed to light (image exposure light) 4 emitted from an exposing device (not shown), a slit exposure device, or a laser beam scanning exposure device. Thus, electrostatic latent images corresponding to objective images are serially formed on the peripheral surface of the electrophotographic photosensitive member 1. The voltage applied to the charging device 3 may be DC voltage only or may be DC voltage superimposed with AC voltage.
The electrostatic latent image formed on the peripheral surface of the electrophotographic photosensitive member 1 is developed by the toner of the developing device 5 into a toner image. Subsequently, the toner image formed on the peripheral surface of the electrophotographic photosensitive member 1 is transferred to a transfer medium (such as paper) P with a transfer bias from a transferring device (such as transfer roller) 6. The transfer medium P is fed to a contact portion between the electrophotographic photosensitive member 1 and the transferring device 6 from a transfer medium supply unit (not shown) in synchronization with the rotation of the electrophotographic photosensitive member 1.
The transfer medium P received the transferred toner image is detached from the peripheral surface of the electrophotographic photosensitive member 1 and is then introduced into a fixing device 8. The transfer medium receives image fixing treatment from the fixing device 8 and is put out to the outside of the apparatus as an image-formed product (e.g., printed matter or copied matter).
The peripheral surface of the electrophotographic photosensitive member 1 after the transfer of the toner image is subjected to removal of the toner remaining on the surface with a cleaning device (such as cleaning blade) 7. The peripheral surface of the electrophotographic photosensitive member 1 is further neutralized with pre-exposing light 11 from a pre-exposing device (not shown) and is repeatedly used for image formation. When the charging device is of a contact type such as a charging roller, pre-exposure is not essential.
The above-described electrophotographic photosensitive member 1 and at least one of the charging device 3, the developing device 5, and the cleaning device 7 can be put in a container to provide a process cartridge integrally supporting them. This process cartridge can be configured to be detachably attachable to an electrophotographic apparatus main body. The process cartridge 9 shown in FIG. 1 integrally supports the electrophotographic photosensitive member 1 and the charging device 3, developing device 5, and cleaning device 7 and is detachably attachable to an electrophotographic apparatus main body with a guiding device 10, such as a rail, of the electrophotographic apparatus main body.
EXAMPLES
The present invention will now be described in more detail by examples, but should not be limited thereto. Note that “part(s)” in examples and comparative examples means “part(s) by mass”. The particle size distributions of the particles in examples and comparative examples each exhibited one peak.
Preparation Examples of Conductive Layer Coating Fluid
Preparation Example
Conductive Layer Coating Fluid 1
A sand mill was charged with 115 parts of first particles, 10 parts of second particles, 168 parts of a binder material, and 98 parts of 1-methoxy-2-propanol serving as a solvent. The mixture was subjected to dispersion treatment using 420 parts of glass beads having a diameter of 0.8 mm at a rotation speed of 1500 rpm for 4 hours to prepare a dispersion. The first particles were titanium oxide particles covered with aluminum-doped zinc oxide (powder resistivity: 5.0×102 Ω·cm, average primary particle diameter: 0.20 μm, density: 4.6 g/cm3, powder resistivity of the core particle (titanium oxide particle): 5.0×107 Ω·cm, average primary particle diameter of the core particle (titanium oxide particle): 0.18 μm, density of the core particle (titanium oxide particle): 4.0 g/cm3); the second particles were titanium oxide particles (powder resistivity: 5.0×107 Ω·cm, average primary particle diameter: 0.20 μm, density: 4.0 g/cm3); and the binder material was a phenolic resin (monomer/oligomer of a phenolic resin) (trade name: Plyophen J-325, manufactured by DIC Corporation, resin solid content: 60%, density after curing: 1.3 g/cm3).
The glass beads were removed from the resulting dispersion with a mesh filter. To the dispersion after the removal of the glass beads were added 13.8 parts of silicone resin particles serving as a surface roughening material (trade name: Tospearl 120, manufactured by Momentive Performance Materials Inc., average particle diameter: 2 μm, density: 1.3 g/cm3), 0.014 parts of silicone oil serving as a leveling agent (trade name: SH28PA, manufactured by Dow Corning Toray Co., Ltd.), 6 parts of methanol, and 6 parts of 1-methoxy-2-propanol. The mixture was stirred to prepare conductive layer coating fluid 1.
Preparation Examples
Conductive Layer Coating Fluids 2 to 114 and C1 to C72
Conductive layer coating fluids 2 to 114 and C1 to C72 were prepared as in the preparation of conductive layer coating fluid 1 except that the types, average primary particle diameters, and amounts (parts) of the first particles and the second particles used were those shown in Tables 1 to 5; in conductive layer coating fluids 18, 36, and 54, the dispersion treatment was conducted at a rotation speed of 2500 rpm for 20 hours; in conductive layer coating fluids 2 to 18, 55 to 66, and C1 to C18, the second particles were titanium oxide particles (density: 4.0 g/cm3); in conductive layer coating fluids 19 to 36, 67 to 78, and C19 to C36, the second particles were zinc oxide particles (density: 5.6 g/cm3); in conductive layer coating fluids 37 to 54, 79 to 90, and C37 to C54, the second particles were tin oxide particles (density: 6.6 g/cm3); and in conductive layer coating fluids 91 to 114 and C55 to C72, the second particles were barium sulfate particles (density: 4.5 g/cm3).









TABLE 1









Binder material













(Phenolic resin)


Conductive
First particle
Second particle
Amount [parts]














layer

Powder
Average primary

Average primary

(including a resin


coating

resistivity
particle diameter
Amount
particle diameter
Amount
solid content of














fluid
Type
[Ω · cm]
[μm]
[parts]
[μm]
[parts]
60% by mass)

















1
Titanium oxide
5.0 × 102
0.20
115
0.20
10
168


2
particle covered
5.0 × 102
0.20
115
0.20
28
168


3
with Al-doped
5.0 × 102
0.20
115
0.20
29
168


4
zinc oxide
5.0 × 102
0.20
105
0.20
0.5
168


5
Density:
5.0 × 102
0.20
290
0.20
23
168


6
4.6 g/cm3
5.0 × 102
0.20
430
0.20
51
168


7

5.0 × 102
0.20
430
0.20
26
168


8

5.0 × 102
0.20
290
0.20
38
168


9

5.0 × 102
0.20
290
0.20
69
168


10

5.0 × 102
0.20
430
0.20
102
168


11

5.0 × 102
0.20
540
0.20
140
168


12

5.0 × 102
0.45
290
0.20
14
168


13

5.0 × 102
0.45
290
0.40
14
168


14

5.0 × 102
0.15
290
0.15
14
168


15

5.0 × 102
0.15
290
0.10
14
168


16

2.0 × 102
0.20
290
0.20
23
168


17

1.5 × 103
0.20
290
0.20
23
168


18

5.0 × 102
0.20
160
0.20
12
168


19
Zinc oxide
5.0 × 102
0.20
135
0.20
12
168


20
particle covered
5.0 × 102
0.20
135
0.20
30
168


21
with Al-doped
5.0 × 102
0.20
135
0.20
31
168


22
zinc oxide
5.0 × 102
0.20
125
0.20
0.8
168


23
Density:
5.0 × 102
0.20
310
0.20
25
168


24
5.6 g/cm3
5.0 × 102
0.20
450
0.20
53
168


25

5.0 × 102
0.20
450
0.20
28
168


26

5.0 × 102
0.20
310
0.20
40
168


27

5.0 × 102
0.20
310
0.20
71
168


28

5.0 × 102
0.20
450
0.20
104
168


29

5.0 × 102
0.20
650
0.20
195
168


30

5.0 × 102
0.45
310
0.20
16
168


31

5.0 × 102
0.45
310
0.40
16
168


32

5.0 × 102
0.15
310
0.15
17
168


33

5.0 × 102
0.15
310
0.10
17
168


34

2.0 × 102
0.20
310
0.20
25
168


35

1.5 × 103
0.20
310
0.20
25
168


36

5.0 × 102
0.20
180
0.20
14
168


37
Tin oxide
5.0 × 102
0.20
160
0.20
14
168


38
particle covered
5.0 × 102
0.20
160
0.20
35
168


39
with Al-doped
5.0 × 102
0.20
160
0.20
35
168


40
zinc oxide
5.0 × 102
0.20
140
0.20
0.9
168


41
Density:
5.0 × 102
0.20
330
0.20
27
168


42
6.2 g/cm3
5.0 × 102
0.20
470
0.20
55
168


43

5.0 × 102
0.20
470
0.20
30
168


44

5.0 × 102
0.20
330
0.20
42
168


45

5.0 × 102
0.20
330
0.20
73
168


46

5.0 × 102
0.20
470
0.20
111
168


47

5.0 × 102
0.20
750
0.20
225
168


48

5.0 × 102
0.45
330
0.20
18
168


49

5.0 × 102
0.45
330
0.40
18
168


50

5.0 × 102
0.15
330
0.15
19
168


51

5.0 × 102
0.15
330
0.10
19
168


52

2.0 × 102
0.20
330
0.20
27
168


53

1.5 × 103
0.20
330
0.20
27
168


54

5.0 × 102
0.20
200
0.20
16
168


















TABLE 2









Binder material













(Phenolic resin)


Conductive
First particle
Second particle
Amount [parts]














layer

Powder
Average primary

Average primary

(including a resin


coating

resistivity
particle diameter
Amount
particle diameter
Amount
solid content of














fluid
Type
[Ω · cm]
[μm]
[parts]
[μm]
[parts]
60% by mass)

















55
Titanium oxide
5.0 × 102
0.20
103
0.20
0.5
168


56
particle
5.0 × 102
0.20
300
0.20
14
168


57
covered with
5.0 × 102
0.20
300
0.20
23
168


58
oxygen-
5.0 × 102
0.20
460
0.20
50
168


59
deficient
5.0 × 102
0.20
300
0.20
38
168


60
zinc oxide
5.0 × 102
0.20
300
0.20
68
168


61
Density:
5.0 × 102
0.20
520
0.20
100
168


62
4.6 g/cm3
5.0 × 102
0.20
560
0.20
145
168


63

5.0 × 102
0.45
300
0.20
23
168


64

5.0 × 102
0.45
300
0.40
23
168


65

5.0 × 102
0.15
300
0.15
23
168


66

5.0 × 102
0.15
300
0.10
23
168


67
Zinc oxide
5.0 × 102
0.20
125
0.20
0.6
168


68
particle
5.0 × 102
0.20
320
0.20
15
168


69
covered with
5.0 × 102
0.20
320
0.20
24
168


70
oxygen-
5.0 × 102
0.20
540
0.20
55
168


71
deficient
5.0 × 102
0.20
320
0.20
40
168


72
zinc oxide
5.0 × 102
0.20
320
0.20
70
168


73
Density:
5.0 × 102
0.20
560
0.20
120
168


74
5.6 g/cm3
5.0 × 102
0.20
600
0.20
180
168


75

5.0 × 102
0.45
320
0.20
25
168


76

5.0 × 102
0.45
320
0.40
25
168


77

5.0 × 102
0.15
320
0.15
25
168


78

5.0 × 102
0.15
320
0.10
25
168


79
Tin oxide
5.0 × 102
0.20
145
0.20
0.8
168


80
particle
5.0 × 102
0.20
340
0.20
17
168


81
covered with
5.0 × 102
0.20
340
0.20
26
168


82
oxygen-
5.0 × 102
0.20
570
0.20
27
168


83
deficient
5.0 × 102
0.20
340
0.20
42
168


84
zinc oxide
5.0 × 102
0.20
340
0.20
75
168


85
Density:
5.0 × 102
0.20
580
0.20
130
168


86
6.2 g/cm3
5.0 × 102
0.20
700
0.20
220
168


87

5.0 × 102
0.45
340
0.20
27
168


88

5.0 × 102
0.45
340
0.40
27
168


89

5.0 × 102
0.15
340
0.15
27
168


90

5.0 × 102
0.15
340
0.10
27
168


















TABLE 3









Binder material













(Phenolic resin)


Conductive
First particle
Second particle
Amount [parts]














layer

Powder
Average primary

Average primary

(including a resin


coating

resistivity
particle diameter
Amount
particle diameter
Amount
solid content of














fluid
Type
[Ω · cm]
[μm]
[parts]
[μm]
[parts]
60% by mass)

















91
Barium sulfate
5.0 × 102
0.20
115
0.20
0.6
168


92
particle
5.0 × 102
0.20
310
0.20
15
168


93
covered with
5.0 × 102
0.20
310
0.20
24
168


94
Al-doped
5.0 × 102
0.20
465
0.20
24
168


95
zinc oxide
5.0 × 102
0.20
310
0.20
38
168


96
Density:
5.0 × 102
0.20
310
0.20
70
168


97
5.0 g/cm3
5.0 × 102
0.20
550
0.20
115
168


98

5.0 × 102
0.20
620
0.20
165
168


99

5.0 × 102
0.45
310
0.20
25
168


100

5.0 × 102
0.45
310
0.40
25
168


101

5.0 × 102
0.15
310
0.15
25
168


102

5.0 × 102
0.15
310
0.10
25
168


103
Barium sulfate
5.0 × 102
0.20
115
0.20
0.6
168


104
particle
5.0 × 102
0.20
310
0.20
15
168


105
covered with
5.0 × 102
0.20
310
0.20
24
168


106
oxygen-
5.0 × 102
0.20
465
0.20
24
168


107
deficient
5.0 × 102
0.20
310
0.20
38
168


108
zinc oxide
5.0 × 102
0.20
310
0.20
70
168


109
Density:
5.0 × 102
0.20
550
0.20
115
168


110
5.0 g/cm3
5.0 × 102
0.20
620
0.20
165
168


111

5.0 × 102
0.45
310
0.20
25
168


112

5.0 × 102
0.45
310
0.40
25
168


113

5.0 × 102
0.15
310
0.15
25
168


114

5.0 × 102
0.15
310
0.10
25
168


















TABLE 4









Binder material













(Phenolic resin)


Conductive
First particle
Second particle
Amount [parts]














layer

Powder
Average primary

Average primary

(including a resin


coating

resistivity
particle diameter
Amount
particle diameter
Amount
solid content of














fluid
Type
[Ω · cm]
[μm]
[parts]
[μm]
[parts]
60% by mass)

















C1 
Titanium oxide
5.0 × 102
0.20
100
0.20
8
168


C2 
particle
5.0 × 102
0.20
480
0.20
50
168













C3 
covered with
5.0 × 102
0.20
250
Not used
168














C4 
Al-doped
5.0 × 102
0.20
250
0.20
0.2
168


C5 
zinc oxide
5.0 × 102
0.20
420
0.20
0.3
168


C6 
Density:
5.0 × 102
0.20
250
0.20
110
168


C7 
4.6 g/cm3
5.0 × 102
0.20
510
0.20
150
168


C8 

5.0 × 102
0.20
250
0.20
0.8
168


C9 

5.0 × 102
0.20
250
0.20
68
168


C10
Titanium oxide
5.0 × 102
0.20
100
0.20
8
168


C11
particle
5.0 × 102
0.20
480
0.20
50
168













C12
covered with
5.0 × 102
0.20
250
Not used
168














C13
oxygen-
5.0 × 102
0.20
250
0.20
0.2
168


C14
deficient
5.0 × 102
0.20
420
0.20
0.3
168


C15
zinc oxide
5.0 × 102
0.20
250
0.20
110
168


C16
Density:
5.0 × 102
0.20
510
0.20
150
168


C17
4.6 g/cm3
5.0 × 102
0.20
250
0.20
0.8
168


C18

5.0 × 102
0.20
250
0.20
68
168


C19
Zinc oxide
5.0 × 102
0.20
120
0.20
8.0
168


C20
particle
5.0 × 102
0.20
560
0.20
50
168













C21
covered with
5.0 × 102
0.20
280
Not used
168














C22
Al-doped
5.0 × 102
0.20
280
0.20
0.3
168


C23
zinc oxide
5.0 × 102
0.20
450
0.20
0.4
168


C24
Density:
5.0 × 102
0.20
280
0.20
160
168


C25
5.6 g/cm3
5.0 × 102
0.20
540
0.20
200
168


C26

5.0 × 102
0.20
280
0.20
0.8
168


C27

5.0 × 102
0.20
280
0.20
93
168


C28
Zinc oxide
5.0 × 102
0.20
120
0.20
8.0
168


C29
particle
5.0 × 102
0.20
560
0.20
50
168













C30
covered with
5.0 × 102
0.20
280
Not used
168














C31
oxygen-
5.0 × 102
0.20
280
0.20
0.3
168


C32
deficient
5.0 × 102
0.20
450
0.20
0.4
168


C33
zinc oxide
5.0 × 102
0.20
280
0.20
160
168


C34
Density:
5.0 × 102
0.20
540
0.20
200
168


C35
5.6 g/cm3
5.0 × 102
0.20
280
0.20
0.8
168


C36

5.0 × 102
0.20
280
0.20
93
168


















TABLE 5









Binder material













(Phenolic resin)


Conductive
First particle
Second particle
Amount [parts]














layer

Powder
Average primary

Average primary

(including a resin


coating

resistivity
particle diameter
Amount
particle diameter
Amount
solid content of














fluid
Type
[Ω · cm]
[μm]
[parts]
[μm]
[parts]
60% by mass)

















C37
Tin oxide
5.0 × 102
0.20
130
0.20
8.0
168


C38
particle
5.0 × 102
0.20
620
0.20
50
168













C39
covered with
5.0 × 102
0.20
310
Not used
168














C40
Al-doped
5.0 × 102
0.20
310
0.20
0.4
168


C41
zinc oxide
5.0 × 102
0.20
470
0.20
0.4
168


C42
Density:
5.0 × 102
0.20
300
0.20
175
168


C43
6.2 g/cm3
5.0 × 102
0.20
560
0.20
230
168


C44

5.0 × 102
0.20
300
0.20
0.8
168


C45

5.0 × 102
0.20
300
0.20
100
168


C46
Tin oxide
5.0 × 102
0.20
130
0.20
8.0
168


C47
particle
5.0 × 102
0.20
620
0.20
50
168













C48
covered with
5.0 × 102
0.20
310
Not used
168














C49
oxygen-
5.0 × 102
0.20
310
0.20
0.4
168


C50
deficient
5.0 × 102
0.20
470
0.20
0.4
168


C51
zinc oxide
5.0 × 102
0.20
300
0.20
175
168


C52
Density:
5.0 × 102
0.20
560
0.20
230
168


C53
6.2 g/cm3
5.0 × 102
0.20
300
0.20
0.8
168


C54

5.0 × 102
0.20
300
0.20
100
168


C55
Barium sulfate
5.0 × 102
0.20
100
0.20
8.0
168


C56
particle
5.0 × 102
0.20
520
0.20
50
168













C57
covered with
5.0 × 102
0.20
250
Not used
168














C58
Al-doped
5.0 × 102
0.20
250
0.20
0.2
168


C59
zinc oxide
5.0 × 102
0.20
440
0.20
0.2
168


C60
Density:
5.0 × 102
0.20
250
0.20
120
168


C61
5.0 g/cm3
5.0 × 102
0.20
530
0.20
180
168


C62

5.0 × 102
0.20
250
0.20
0.6
168


C63

5.0 × 102
0.20
250
0.20
73
168


C64
Barium sulfate
5.0 × 102
0.20
100
0.20
8.0
168


C65
particle
5.0 × 102
0.20
520
0.20
50
168













C66
covered with
5.0 × 102
0.20
250
Not used
168














C67
oxygen-
5.0 × 102
0.20
250
0.20
0.2
168


C68
deficient
5.0 × 102
0.20
440
0.20
0.2
168


C69
zinc oxide
5.0 × 102
0.20
250
0.20
120
168


C70
Density:
5.0 × 102
0.20
530
0.20
180
168


C71
5.0 g/cm3
5.0 × 102
0.20
250
0.20
0.6
168


C72

5.0 × 102
0.20
250
0.20
73
168









Preparation Example
Conductive Layer Coating Fluid 115
Conductive layer coating fluid 115 was prepared as in the preparation of conductive layer coating fluid 8 except that in addition to the first particles and the second particles, 30 parts of aluminum-doped zinc oxide particles (powder resistivity: 5.0×10 Ω·cm, average primary particle diameter: 0.02 μm, density: 5.6 g/cm3) were added to the fluid.
Preparation Example
Conductive Layer Coating Fluid C73
Conductive layer coating fluid C73 was prepared as in the preparation of conductive layer coating fluid 8 except that 38 parts of tin oxide particles (powder resistivity: 5.0×107 Ω·cm, average primary particle diameter: 0.20 μm, density: 6.6 g/cm3) were used instead of the second particles used in the preparation of conductive layer coating fluid 8.
Preparation Example
Conductive Layer Coating Fluid C74
Conductive layer coating fluid C74 was prepared as in the preparation of conductive layer coating fluid 26 except that 40 parts of titanium oxide particles (powder resistivity: 5.0×107 Ω·cm, average primary particle diameter: 0.20 μm, density: 4.0 g/cm3) were used instead of the second particles used in the preparation of conductive layer coating fluid 26.
Preparation Example
Conductive Layer Coating Fluid C75
Conductive layer coating fluid C75 was prepared as in the preparation of conductive layer coating fluid 44 except that 42 parts of zinc oxide particles (powder resistivity: 5.0×107 Ω·cm, average primary particle diameter: 0.20 μm, density: 5.6 g/cm3) were used instead of the second particles used in the preparation of conductive layer coating fluid 44.
Preparation Example
Conductive Layer Coating Fluid C76
Conductive layer coating fluid C76 was prepared as in the preparation of conductive layer coating fluid 26 except that 350 parts of aluminum-doped zinc oxide particles (powder resistivity: 5.0×10 Ω·cm, average primary particle diameter: 0.20 μm, density: 5.6 g/cm3) only were used instead of the first particles and the second particles used in the preparation of conductive layer coating fluid 26.
Preparation Example
Conductive Layer Coating Fluid C77
Conductive layer coating fluid C77 was prepared as in the preparation of conductive layer coating fluid 26 except that 310 parts of aluminum-doped zinc oxide particles (powder resistivity: 5.0×10 Ω·cm, average primary particle diameter: 0.20 μm, density: 5.6 g/cm3) were used instead of the first particles used in the preparation of conductive layer coating fluid 26.
Preparation Example
Conductive Layer Coating Fluid C78
Conductive layer coating fluid C78 was prepared as in the preparation of conductive layer coating fluid 8 except that 160 parts of zinc oxide particles (powder resistivity: 5.0×107 Ω·cm, average primary particle diameter: 0.20 μm, density: 5.6 g/cm3) and 160 parts of tin oxide particles (powder resistivity: 5.0×107 Ω·cm, average primary particle diameter: 0.20 μm, density: 6.6 g/cm3) were used instead of the first particles and the second particles used in the preparation of conductive layer coating fluid 8.
Preparation Example
Conductive Layer Coating Fluid C79
Conductive layer coating fluid C79 was prepared as in the preparation of conductive layer coating fluid 8 except that 160 parts of zinc oxide particles (powder resistivity: 5.0×107 Ω·cm, average primary particle diameter: 0.20 μm, density: 5.6 g/cm3) and 160 parts of titanium oxide particles (powder resistivity: 5.0×107 Ω·cm, average primary particle diameter: 0.20 μm, density: 4.0 g/cm3) were used instead of the first particles and the second particles used in the preparation of conductive layer coating fluid 8.
Preparation Example
Conductive Layer Coating Fluid C80
Conductive layer coating fluid C80 was prepared as in the preparation of conductive layer coating fluid 26 except that 350 parts of combined metal oxide particles 1 (particles each composed of a titanium oxide particle and a zinc oxide layer on the titanium oxide particle) described in Japanese Patent Laid-Open No. 2005-234396 were used instead of the first particles and the second particles used in the preparation of conductive layer coating fluid 26.
Preparation Example
Conductive Layer Coating Fluid C81
Conductive layer coating fluid C81 was prepared as in the preparation of conductive layer coating fluid 26 except that 350 parts of combined metal oxide particles 2 (particles each composed of a titanium oxide particle and a zinc oxide layer covering the surface of the titanium oxide particle) described in Japanese Patent Laid-Open No. 2005-234396 were used instead of the first particles and the second particles used in the preparation of conductive layer coating fluid 26.
Preparation Example
Conductive Layer Coating Fluid C82
Conductive layer coating fluid C82 was prepared as in the preparation of conductive layer coating fluid 26 except that 350 parts of titanium oxide particles 1 not surface-treated with the silane coupling agent described in Japanese Patent Laid-Open No. 2010-224173 were used instead of the first particles and the second particles used in the preparation of conductive layer coating fluid 26.
Preparation Example
Conductive Layer Coating Fluid C83
Conductive layer coating fluid C83 was prepared as in the preparation of conductive layer coating fluid 26 except that 350 parts of titanium oxide particles 4 not surface-treated with the silane coupling agent described in Japanese Patent Laid-Open No. 2010-224173 were used instead of the first particles and the second particles used in the preparation of conductive layer coating fluid 26.
Production Examples of Electrophotographic Photosensitive Member
Production Example
Electrophotographic Photosensitive Member 1
An aluminum cylinder (JIS-A3003, aluminum alloy) having a length of 257 mm and a diameter of 24 mm produced by a method including an extrusion step and a drawing step was used as a support (conductive support).
The support was immersed in conductive layer coating fluid 1 in an ordinary temperature and ordinary humidity (23° C./50% RH) environment to form a coating film on the support, and the coating film was dried and heat-cured at 150° C. for 20 minutes. Thus, a conductive layer having a thickness of 30 μm was formed.
The conductive layer had a volume resistivity of 1.8×1012 Ω·cm measured by the above-described method.
An undercoat layer coating fluid was prepared by dissolving 4.5 parts of N-methoxymethylated nylon (trade name: Trezin EF-30T, manufactured by Nagase ChemteX Corporation) and 1.5 parts of a copolymer nylon resin (trade name: Amilan CM8000, manufactured by Toray Industries, Inc.) in a solvent mixture of 65 parts of methanol and 30 parts of n-butanol. The support provided with the conductive layer was immersed in the undercoat layer coating fluid to form a coating film on the conductive layer, and the coating film was dried at 70° C. for 6 minutes. Thus, an undercoat layer having a thickness of 0.85 μm was formed.
Hydroxygallium phthalocyanine (charge generation material) in a crystal form exhibiting peaks at Bragg angles) (2θ±0.2° of 7.5°, 9.9°, 16.3°, 18.6°, 25.1°, and 28.3° in the CuKα characteristic X-ray diffraction was prepared. A sand mill was charged with 10 parts of the hydroxygallium phthalocyanine crystal, 5 parts of polyvinyl butyral (trade name: Eslex BX-1, manufactured by Sekisui Chemical Co., Ltd.), and 250 parts of cyclohexanone. The mixture was subjected to dispersion treatment using glass beads having a diameter of 0.8 mm for 3 hours. To the resulting dispersion was added 250 parts of ethyl acetate to prepare a charge generating layer coating fluid. The support provided with the undercoat layer was immersed in the charge generating layer coating fluid to form a coating film on the undercoat layer, and the coating film was dried at 100° C. for 10 minutes. Thus, a charge generating layer having a thickness of 0.15 μm was formed.
A charge transporting layer coating fluid was prepared by dissolving the following components in a solvent mixture of 60 parts of o-xylene, 40 parts of dimethoxymethane, and 2.7 parts of methyl benzoate. The components were 6.0 parts of an amine compound (charge transport material) represented by Formula (CT-1):




2.0 parts of an amine compound (charge transport material) represented by Formula (CT-2):





10 parts of bisphenol-Z polycarbonate (trade name: 2400, manufactured by Mitsubishi Engineering-Plastics Corporation), and

0.36 parts of siloxane-modified polycarbonate including a structural unit represented by Formula (B-1), a structural unit represented by Formula (B-2), and a terminal structure represented by Formula (B-3):





at a molar ratio of (B−1):(B-2):(B-3)=67:11:22. The support provided with the charge generating layer was immersed in this charge transporting layer coating fluid to form a coating film on the charge generating layer, and the coating film was dried at 125° C. for 30 minutes. Thus, a charge transporting layer having a thickness of 10.0 μm was formed to complete the production of electrophotographic photosensitive member 1 having the charge transporting layer as the surface layer.

Production Examples
Electrophotographic Photosensitive Members 2 to 115 and C1 to C83
Electrophotographic photosensitive members 2 to 115 and C1 to C83 each having a charge transporting layer as the surface layer were produced as in the production example of electrophotographic photosensitive member 1 except that conductive layer coating fluids 2 to 115 and C1 to C83 were used instead of conductive layer coating fluid 1 used in the production of electrophotographic photosensitive member 1. The volume resistivity of each conductive layer was measured as in electrophotographic photosensitive member 1. The results are shown in Tables 6 to 9.
Electrophotographic photosensitive members 1 to 115 and C1 to C83 were each produced two, one for conductive layer analysis and the other for a repeating paper-feeding test.
Production Examples
Electrophotographic Photosensitive Members 116 to 230 and C84 to C166
Electrophotographic photosensitive members 116 to 230 and C84 to C166, for a needle breakdown voltage test, each having a charge transporting layer as the surface layer were respectively produced as in the production examples of electrophotographic photosensitive member 1 to 115 and C1 to C83 except that the charge transporting layer had a thickness of 5.0 μm.
Examples 1 to 115 and Comparative Examples 1 to 83
Analysis of Conductive Layer of Electrophotographic Photosensitive Member
Five pieces of 5 mm square were cut from each of electrophotographic photosensitive members 1 to 115 and C1 to C83 for conductive layer analysis. The charge transporting layer, the charge generating layer, and the undercoat layer of each piece were removed by dissolving the layers in chlorobenzene, methyl ethyl ketone, and methanol to expose the conductive layer. Thus, five sample pieces were prepared for each electrophotographic photosensitive member.
The conductive layer of one of the five sample pieces of each electrophotographic photosensitive member was reduced in thickness to 150 nm with a focused ion beam (FIB) system (trade name: FB-2000A, manufactured by Hitachi High-Tech Manufacturing & Service Corporation) for processing and observing by an FIB micro-sampling method. Composition analysis of the conductive layer was performed with a high-resolution transmission electron microscope (HRTEM) (trade name: JEM-2100F, manufactured by JEOL Ltd.) and an energy dispersive X-ray spectrometer (EDX) (trade name: JED-2300T, manufactured by JEOL Ltd.). The measurement conditions of the EDX were an accelerating voltage of 200 kV and a beam diameter of 1.0 nm.
The results demonstrated that titanium oxide particles covered with aluminum-doped zinc oxide were contained in the conductive layers of electrophotographic photosensitive members 1 to 18, 115, C1 to C9, and C73; zinc oxide particles covered with aluminum-doped zinc oxide were contained in the conductive layers of electrophotographic photosensitive members 19 to 36, C19 to C27, and C74; tin oxide particles covered with aluminum-doped zinc oxide were contained in the conductive layers of electrophotographic photosensitive members 37 to 54, C37 to C45, and C75; and barium sulfate particles covered with aluminum-doped zinc oxide were contained in the conductive layers of electrophotographic photosensitive members 91 to 102 and C55 to C63.
The results also demonstrated that titanium oxide particles covered with zinc oxide were contained in the conductive layers of electrophotographic photosensitive members 55 to 66, C10 to C18, and C80 to C83; zinc oxide particles covered with zinc oxide were contained in the conductive layers of electrophotographic photosensitive members 67 to 78 and C28 to C36; tin oxide particles covered with zinc oxide were contained in the conductive layers of electrophotographic photosensitive members 79 to 90 and C46 to C54; and barium sulfate particles covered with zinc oxide were contained in the conductive layers of electrophotographic photosensitive members 103 to 114 and C64 to C72.
The results also demonstrated that aluminum-doped zinc oxide particles were contained in the conductive layers of electrophotographic photosensitive members 115, C76, and C77. The results also demonstrated that titanium oxide particles were contained in the conductive layers of electrophotographic photosensitive members 1 to 18, 55 to 66, 115, C1, C2, C4 to C11, C13 to C18, C74, and C79; zinc oxide particles were contained in the conductive layers of electrophotographic photosensitive members 19 to 36, 67 to 78, C19, C20, C22 to C29, C31 to C36, C75, C78, and C79; tin oxide particles were contained in the conductive layers of electrophotographic photosensitive members 37 to 54, 79 to 90, C37, C38, C40 to C47, C49 to C54, C73, and C78; and barium sulfate particles were contained in the conductive layers of electrophotographic photosensitive members 91 to 114, C55, C56, C58 to C65, and C67 to C72.
The conductive layers of remaining four sample pieces of each electrophotographic photosensitive member were observed in the region of 2 μm in length, 2 μm in width, and 2 μm in thickness with slice-and-view in FIB-SEM, and rendering was performed. A difference in contrast of slice-and-view in FIB-SEM can specify, for example, titanium oxide particles covered with aluminum-doped zinc oxide and titanium oxide particles. Furthermore, the volume of titanium oxide particles covered with aluminum-doped zinc oxide, the volume of titanium oxide particles, and the ratios of these particles in the conductive layer can be determined. Similarly, the volume of zinc oxide particles covered with aluminum-doped zinc oxide, the volume of zinc oxide particles, and the ratios of these particles in the conductive layer can be determined; the volume of tin oxide particles covered with aluminum-doped zinc oxide, the volume of tin oxide particles, and the ratios of these particles in the conductive layer can be determined; the volume of barium sulfate particles covered with aluminum-doped zinc oxide, the volume of barium sulfate particle, and the ratios of these particles in the conductive layer can be determined; the volume of titanium oxide particles covered with oxygen-deficient zinc oxide, the volume of titanium oxide particles, and the ratios of these particles in the conductive layer can be determined; the volume of zinc oxide particles covered with oxygen-deficient zinc oxide, the volume of zinc oxide particles, and the ratios of these particles in the conductive layer can be determined; the volume tin oxide particles covered with oxygen-deficient zinc oxide, the volume of tin oxide particles, and the ratios of these particles in the conductive layer can be determined; the volume of barium sulfate particles covered with oxygen-deficient zinc oxide, the volume of barium sulfate particles, and the ratios of these particles in the conductive layer can be determined; and the volume of aluminum-doped zinc oxide particles can be determined.
The conditions of slice-and-view in the present invention were as follows:
Sample processing for analysis: FIB method
Processing and observation apparatus: NVision 40 manufactured by SII/Zeiss
Slice interval: 10 nm
Observation conditions:
Accelerating voltage: 1.0 kV
Sample tilting: 54°
WD: 5 mm
Detector: BSE detector
Aperture: 60 μm, high current
ABC: ON
Image resolution: 1.25 nm/pixel
The analytical region was 2 μm in length and 2 μm in width. The information on the respective cross-sections were added up, and each particle volume per unit volume (8 μm3: 2 μm in length×2 μm in with×2 μm in thickness) was determined. The measurement environment was a temperature of 23° C. and a pressure of 1×10−4 Pa.
The processing and observation apparatus may be Strata 400S (sample tilting: 52°) manufactured by FEI Company.
The information on each cross section was obtained through image analysis of specified, for example, the area of titanium oxide particles covered with aluminum-doped zinc oxide and the area of titanium oxide particles not covered with the zinc oxide. The image analysis was performed using image processing software: Image-Pro Plus manufactured by Media Cybernetics, Inc.
From the information, the volume (V1 (μm3)) of the first particles and the volume (V2 (μm3)) of the second particles in unit volume (8 μm3: 2 μm×2 μm×2 μm) were determined for each of the four sample pieces of each electrophotographic photosensitive member. The values of (V1 (μm3)/8 (μm3))×100, (V2 (μm3)/8 (μm3))×100, and (V2 (μm3)/V1 (μm3))×100 were further calculated. The average value of the (V1 (μm3)/8 (μm3))×100 values of four sample pieces was defined as the content (% by volume) of the first particles in the conductive layer based on the total volume of the conductive layer. The average value of the (V2 (μm3)/8 (μm3))×100 values of the four sample pieces was defined as the content (% by volume) of the second particles in the conductive layer based on the total volume of the conductive layer. The average value of the values of (V2 (μm3)/V1 (μm3))×100 of the four sample pieces was defined as the content (% by volume) of the second particles based on that of the first particles in the conductive layer.
The average primary particle diameter of the first particles and the average primary particle diameter of the second particles were determined for each of the four sample pieces. The average primary particle diameter (μm) is the arithmetic mean of the measured diameters of individual first or second particles in an analytical region of 2 μm in length and 2 μm in width. Each particle diameter was calculated as the value of (a+b)/2 of the longest side “a” and the shortest side “b” of a primary particle. The information on the respective cross-sections were added up, and each average primary particle diameter per unit volume (8 μm3: 2 μm in length×2 μm in with×2 μm in thickness) was determined.
The average value of the average primary particle diameters of the first particles in the four sample pieces was defined as the average primary particle diameter (D1) of the first particles in the conductive layer. The average value of the average primary particle diameters of the second particles in the four sample pieces was defined as the average primary particle diameter (D2) of the second particles in the conductive layer.
The results are shown in Tables 6 to 9.
















TABLE 6










Content of











second particle



Conductive
Electro-
Content of
Content of
relative to



Volume



layer
photographic
first
second
that of first



resistivity of



coating
photosensitive
particle
particle
particle
D1
D2

conductive layer


Example
fluid
member
(% by vol.)
(% by vol.)
(% by vol.)
(μm)
(μm)
D1/D2
(Ω · cm)
























1
1
1
22
2.2
10.0
0.20
0.20
1.0
1.8 × 1012


2
2
2
21
5.8
27.6
0.20
0.20
1.0
2.0 × 1012


3
3
3
21
6.0
28.6
0.20
0.20
1.0
2.0 × 1012


4
4
4
21
0.1
0.50
0.20
0.20
1.0
2.0 × 1012


5
5
5
40
3.7
9.3
0.20
0.20
1.0
6.3 × 1010


6
6
6
48
6.6
13.8
0.20
0.20
1.0
5.5 × 108 


7
7
7
50
3.5
7.0
0.20
0.20
1.0
4.5 × 108 


8
8
8
39
5.9
15.1
0.20
0.20
1.0
6.5 × 1010


9
9
9
37
10.2
27.6
0.20
0.20
1.0
7.0 × 1010


10
10
10
45
12.3
27.3
0.20
0.20
1.0
2.0 × 109 


11
11
11
49
14.6
29.8
0.20
0.20
1.0
5.0 × 108 


12
12
12
41
2.3
5.6
0.45
0.20
2.3
6.0 × 1010


13
13
13
41
2.3
5.6
0.45
0.40
1.1
6.0 × 1010


14
14
14
41
2.3
5.6
0.15
0.15
1.0
6.0 × 1010


15
15
15
41
2.3
5.6
0.15
0.10
1.5
6.0 × 1010


16
16
16
40
3.7
9.3
0.20
0.20
1.0
6.3 × 109 


17
17
17
40
3.7
9.3
0.20
0.20
1.0
6.3 × 1011


18
18
18
28
2.4
8.6
0.20
0.18
1.1
1.2 × 1012


19
19
19
21
1.9
9.0
0.20
0.20
1.0
2.0 × 1012


20
20
20
21
4.6
21.9
0.20
0.20
1.0
2.0 × 1012


21
21
21
21
4.7
22.4
0.20
0.20
1.0
2.0 × 1012


22
22
22
20
0.1
0.5
0.20
0.20
1.0
5.0 × 1012


23
23
23
37
3.0
8.1
0.20
0.20
1.0
7.0 × 1010


24
24
24
45
5.3
11.8
0.20
0.20
1.0
2.0 × 109 


25
25
25
46
2.9
6.3
0.20
0.20
1.0
1.0 × 109 


26
26
26
37
4.7
12.7
0.20
0.20
1.0
7.0 × 1010


27
27
27
35
8.1
23.1
0.20
0.20
1.0
1.0 × 1011


28
28
28
43
9.9
23.0
0.20
0.20
1.0
3.0 × 1010


29
29
29
49
14.6
29.8
0.20
0.20
1.0
5.0 × 108 


30
30
30
38
2.0
5.3
0.45
0.20
2.3
6.7 × 1010


31
31
31
38
2.0
5.3
0.45
0.40
1.1
6.7 × 1010


32
32
32
38
2.1
5.5
0.15
0.15
1.0
6.7 × 1010


33
33
33
38
2.1
5.5
0.15
0.10
1.5
6.7 × 1010


34
34
34
37
3.0
8.1
0.20
0.20
1.0
7.0 × 109 


35
35
35
37
3.0
8.1
0.20
0.20
1.0
7.0 × 1011


36
36
36
26
2.0
7.7
0.20
0.18
1.1
1.6 × 1012


37
37
37
22
1.8
8.2
0.20
0.20
1.0
1.8 × 1012


38
38
38
22
4.1
20.5
0.20
0.20
1.0
1.8 × 1012


39
39
39
22
4.2
20.5
0.20
0.20
1.0
1.8 × 1012


40
40
40
20
0.1
0.5
0.20
0.20
1.0
5.0 × 1012


41
41
41
37
2.8
7.6
0.20
0.20
1.0
7.0 × 1010


42
42
42
44
4.8
10.9
0.20
0.20
1.0
8.0 × 109 


43
43
43
45
2.7
6.0
0.20
0.20
1.0
2.0 × 109 


44
44
44
36
4.3
11.9
0.20
0.20
1.0
8.5 × 1010


45
45
45
35
7.3
20.9
0.20
0.20
1.0
1.0 × 1011


46
46
46
42
9.2
21.9
0.20
0.20
1.0
4.5 × 1010


47
47
47
50
14.0
28.0
0.20
0.20
1.0
4.5 × 108 


48
48
48
37
1.9
5.1
0.45
0.20
2.3
7.0 × 1010


49
49
49
37
1.9
5.1
0.45
0.40
1.1
7.0 × 1010


50
50
50
37
2.0
5.4
0.15
0.15
1.0
7.0 × 1010


51
51
51
37
2.0
5.4
0.15
0.10
1.5
7.0 × 1010


52
52
52
37
2.8
7.6
0.20
0.20
1.0
7.0 × 109 


53
53
53
37
2.8
7.6
0.20
0.20
1.0
7.0 × 1011


54
54
54
26
2.0
7.7
0.20
0.18
1.1
1.6 × 1012

























TABLE 7










Content of











second particle



Conductive
Electro-
Content of
Content of
relative to



Volume



layer
photographic
first
second
that of first



resistivity of



coating
photosensitive
particle
particle
particle
D1
D2

conductive layer


Example
fluid
member
(% by vol.)
(% by vol.)
(% by vol.)
(μm)
(μm)
D1/D2
(Ω · cm)
























55
55
55
20
0.1
0.5
0.20
0.20
1.0
2.0 × 1012


56
56
56
42
2.2
5.2
0.20
0.20
1.0
4.5 × 1010


57
57
57
41
3.6
8.8
0.20
0.20
1.0
6.0 × 1010


58
58
58
50
6.2
12.4
0.20
0.20
1.0
4.5 × 108 


59
59
59
40
5.8
14.5
0.20
0.20
1.0
6.3 × 1010


60
60
60
38
10
26.3
0.20
0.20
1.0
6.7 × 1010


61
61
61
50
11.1
22.2
0.20
0.20
1.0
4.5 × 108 


62
62
62
50
14.7
29.4
0.20
0.20
1.0
4.5 × 108 


63
63
63
41
3.6
8.8
0.45
0.20
2.3
6.0 × 1010


64
64
64
41
3.6
8.8
0.45
0.40
1.1
6.0 × 1010


65
65
65
41
3.6
8.8
0.15
0.15
1.0
6.0 × 1010


66
66
66
41
3.6
8.8
0.15
0.10
1.5
6.0 × 1010


67
67
67
20
0.1
0.5
0.20
0.20
1.0
2.0 × 1012


68
68
68
39
1.8
4.6
0.20
0.20
1.0
6.5 × 1010


69
69
69
38
2.9
7.6
0.20
0.20
1.0
6.7 × 1010


70
70
70
50
5.1
10.2
0.20
0.20
1.0
4.5 × 108 


71
71
71
38
4.7
12.4
0.20
0.20
1.0
6.7 × 1010


72
72
72
36
7.9
21.9
0.20
0.20
1.0
8.5 × 1010


73
73
73
48
10.2
21.3
0.20
0.20
1.0
5.5 × 108 


74
74
74
47
14.1
30.0
0.20
0.20
1.0
8.0 × 108 


75
75
75
38
3.0
7.9
0.45
0.20
2.3
6.7 × 1010


76
76
76
38
3.0
7.9
0.45
0.40
1.1
6.7 × 1010


77
77
77
38
3.0
7.9
0.15
0.15
1.0
6.7 × 1010


78
78
78
38
3.0
7.9
0.15
0.10
1.5
6.7 × 1010


79
79
79
21
0.1
0.5
0.20
0.20
1.0
2.0 × 1012


80
80
80
38
1.8
4.7
0.20
0.20
1.0
6.7 × 1010


81
81
81
37
2.7
7.3
0.20
0.20
1.0
7.0 × 1010


82
82
82
50
2.2
4.4
0.20
0.20
1.0
4.5 × 108 


83
83
83
37
4.3
11.6
0.20
0.20
1.0
7.0 × 1010


84
84
84
36
7.4
20.6
0.20
0.20
1.0
8.5 × 1010


85
85
85
47
9.4
21.1
0.20
0.20
1.0
8.0 × 108 


86
86
86
48
14.2
29.6
0.20
0.20
1.0
5.5 × 108 


87
87
87
37
2.8
7.6
0.45
0.20
2.3
7.0 × 1010


88
88
88
37
2.8
7.6
0.45
0.40
1.1
7.0 × 1010


89
89
89
37
2.8
7.6
0.15
0.15
1.0
7.0 × 1010


90
90
90
37
2.8
7.6
0.15
0.10
1.5
7.0 × 1010


91
91
91
21
0.1
0.5
0.20
0.20
1.0
2.0 × 1012


92
92
92
40
2.2
5.5
0.20
0.20
1.0
6.3 × 1010


93
93
93
40
3.4
8.5
0.20
0.20
1.0
6.3 × 1010


94
94
94
50
2.9
5.8
0.20
0.20
1.0
4.5 × 108 


95
95
95
39
5.3
13.6
0.20
0.20
1.0
6.5 × 1010


96
96
96
37
9.4
25.4
0.20
0.20
1.0
7.0 × 1010


97
97
97
49
11.4
23.3
0.20
0.20
1.0
5.0 × 108 


98
98
98
50
14.7
29.4
0.20
0.20
1.0
4.5 × 108 


99
99
99
40
3.6
9.0
0.45
0.20
2.3
6.3 × 1010


100
100
100
40
3.6
9.0
0.45
0.40
1.1
6.3 × 1010


101
101
101
40
3.6
9.0
0.15
0.15
1.0
6.3 × 1010


102
102
102
40
3.6
9.0
0.15
0.10
1.5
6.3 × 1010

























TABLE 8










Content of











second particle



Volume



Conductive
Electro-
Content of
Content of
relative to



resistivity of



layer
photographic
first
second
that of first



conductive


Example/Comparative
coating
photosensitive
particle
particle
particle
D1
D2

layer


Example
fluid
member
(% by vol.)
(% by vol.)
(% by vol.)
(μm)
(μm)
D1/D2
(Ω · cm)
























103
103
103
21
0.1
0.5
0.20
0.20
1.0
2.0 × 1012


104
104
104
40
2.2
5.5
0.20
0.20
1.0
6.3 × 1010


105
105
105
40
3.4
8.5
0.20
0.20
1.0
6.3 × 1010


106
106
106
50
2.9
5.8
0.20
0.20
1.0
4.5 × 108 


107
107
107
39
5.3
13.6
0.20
0.20
1.0
6.5 × 1010


108
108
108
37
9.4
25.4
0.20
0.20
1.0
7.0 × 1010


109
109
109
49
11.4
23.3
0.20
0.20
1.0
4.5 × 108 


110
110
110
50
14.7
29.4
0.20
0.20
1.0
5.0 × 108 


111
111
111
40
3.6
9.0
0.45
0.20
2.3
6.3 × 1010


112
112
112
40
3.6
9.0
0.45
0.40
1.1
6.3 × 1010


113
113
113
40
3.6
9.0
0.15
0.15
1.0
6.3 × 1010


114
114
114
40
3.6
9.0
0.15
0.10
1.5
6.3 × 1010


115
115
115
38
5.7
15.0
0.20
0.20
1.0
6.5 × 109 


Comparative Example 1 
C1 
C1 
19
1.8
9.5
0.20
0.20
1.0
1.0 × 1013


Comparative Example 2 
C2 
C2 
51
6.1
12.0
0.20
0.20
1.0
3.0 × 108 


Comparative Example 3 
C3 
C3 
38
—
—
0.20
—
—
6.7 × 1010


Comparative Example 4 
C4 
C4 
38
0.04
0.1
0.20
0.20
1.0
6.7 × 1010


Comparative Example 5 
C5 
C5 
51
0.04
0.1
0.20
0.20
1.0
3.0 × 108 


Comparative Example 6 
C6 
C6 
32
16.2
50.6
0.20
0.20
1.0
8.0 × 1011


Comparative Example 7 
C7 
C7 
47
15.9
33.8
0.20
0.20
1.0
8.0 × 108 


Comparative Example 8 
C8 
C8 
38
0.14
0.4
0.20
0.20
1.0
6.7 × 1010


Comparative Example 9 
C9 
C9 
34
10.7
31.5
0.20
0.20
1.0
5.0 × 1011


Comparative Example 10
C10
C10
19
1.8
9.5
0.20
0.20
1.0
1.0 × 1013


Comparative Example 11
C11
C11
51
6.1
12.0
0.20
0.20
1.0
3.0 × 108 


Comparative Example 12
C12
C12
38
—
—
0.20
—
—
6.7 × 1010


Comparative Example 13
C13
C13
38
0.04
0.1
0.20
0.20
1.0
6.7 × 1010


Comparative Example 14
C14
C14
51
0.04
0.1
0.20
0.20
1.0
3.0 × 108 


Comparative Example 15
C15
C15
32
16.2
50.6
0.20
0.20
1.0
8.0 × 1011


Comparative Example 16
C16
C16
47
15.9
33.8
0.20
0.20
1.0
8.0 × 108 


Comparative Example 17
C17
C17
38
0.14
0.4
0.20
0.20
1.0
6.7 × 1010


Comparative Example 18
C18
C18
34
10.7
31.5
0.20
0.20
1.0
5.0 × 1011


Comparative Example 19
C19
C19
19
1.3
6.8
0.20
0.20
1.0
1.0 × 1013


Comparative Example 20
C20
C20
51
4.5
8.8
0.20
0.20
1.0
3.0 × 108 


Comparative Example 21
C21
C21
36
—
—
0.20
—
-
8.5 × 1010


Comparative Example 22
C22
C22
36
0.04
0.1
0.20
0.20
1.0
8.5 × 1010


Comparative Example 23
C23
C23
48
0.04
0.1
0.20
0.20
1.0
5.5 × 108 


Comparative Example 24
C24
C24
30
17.1
57
0.20
0.20
1.0
9.0 × 1011


Comparative Example 25
C25
C25
44
16.2
36.8
0.20
0.20
1.0
8.0 × 109 


Comparative Example 26
C26
C26
36
0.1
0.3
0.20
0.20
1.0
8.5 × 1010


Comparative Example 27
C27
C27
33
10.7
32.4
0.20
0.20
1.0
6.5 × 1011


Comparative Example 28
C28
C28
19
1.3
6.8
0.20
0.20
1.0
1.0 × 1013


Comparative Example 29
C29
C29
51
4.5
8.8
0.20
0.20
1.0
3.0 × 108 


Comparative Example 30
C30
C30
36
—
—
0.20
—
—
8.5 × 1010


Comparative Example 31
C31
C31
36
0.04
0.1
0.20
0.20
1.0
8.5 × 1010


Comparative Example 32
C32
C32
48
0.04
0.1
0.20
0.20
1.0
5.5 × 108 


Comparative Example 33
C33
C33
30
17.1
57
0.20
0.20
1.0
9.0 × 1011


Comparative Example 34
C34
C34
44
16.2
36.8
0.20
0.20
1.0
8.0 × 109 


Comparative Example 35
C35
C35
36
0.1
0.3
0.20
0.20
1.0
8.5 × 1010


Comparative Example 36
C36
C36
33
10.7
32.4
0.20
0.20
1.0
6.5 × 1011

























TABLE 9










Content of











second particle



Volume



Conductive
Electro-
Content of
Content of
relative to



resistivity of



layer
photographic
first
second
that of first



conductive


Example/Comparative
coating
photosensitive
particle
particle
particle
D1
D2

layer


Example
fluid
member
(% by vol.)
(% by vol.)
(% by vol.)
(μm)
(μm)
D1/D2
(Ω · cm)
























Comparative Example 37
C37
C37
19
1.1
5.8
0.20
0.20
1.0
1.0 × 1013


Comparative Example 38
C38
C38
51
3.9
7.6
0.20
0.20
1.0
3.0 × 108 


Comparative Example 39
C39
C39
36
—
—
0.20
—
—
8.5 × 1010


Comparative Example 40
C40
C40
36
0.04
0.1
0.20
0.20
1.0
8.5 × 1010


Comparative Example 41
C41
C41
46
0.04
0.1
0.20
0.20
1.0
1.0 × 109 


Comparative Example 42
C42
C42
30
16.3
54.3
0.20
0.20
1.0
9.0 × 1011


Comparative Example 43
C43
C43
42
16.2
38.6
0.20
0.20
1.0
4.5 × 1010


Comparative Example 44
C44
C44
35
0.1
0.3
0.20
0.20
1.0
1.0 × 1011


Comparative Example 45
C45
C45
32
10.0
31.3
0.20
0.20
1.0
8.0 × 1011


Comparative Example 46
C46
C46
19
1.1
5.8
0.20
0.20
1.0
1.0 × 1013


Comparative Example 47
C47
C47
51
3.9
7.6
0.20
0.20
1.0
3.0 × 108 


Comparative Example 48
C48
C48
36
—
—
0.20
—
—
8.5 × 1010


Comparative Example 49
C49
C49
36
0.04
0.1
0.20
0.20
1.0
8.5 × 1010


Comparative Example 50
C50
C50
46
0.04
0.1
0.20
0.20
1.0
1.0 × 109 


Comparative Example 51
C51
C51
30
16.3
54.3
0.20
0.20
1.0
9.0 × 1011


Comparative Example 52
C52
C52
42
16.2
38.6
0.20
0.20
1.0
4.5 × 1010


Comparative Example 53
C53
C53
35
0.1
0.3
0.20
0.20
1.0
1.0 × 1011


Comparative Example 54
C54
C54
32
10.0
31.3
0.20
0.20
1.0
8.0 × 1011


Comparative Example 55
C55
C55
18
1.6
8.9
0.20
0.20
1.0
5.0 × 1013


Comparative Example 56
C56
C56
51
5.5
10.8
0.20
0.20
1.0
3.0 × 108 


Comparative Example 57
C57
C57
36
—
—
0.20
—
—
8.5 × 1010


Comparative Example 58
C58
C58
36
0.03
0.1
0.20
0.20
1.0
8.5 × 1010


Comparative Example 59
C59
C59
50
0.03
0.1
0.20
0.20
1.0
4.5 × 108 


Comparative Example 60
C60
C60
30
16.2
54
0.20
0.20
1.0
9.0 × 1011


Comparative Example 61
C61
C61
45
17.1
38
0.20
0.20
1.0
2.0 × 109 


Comparative Example 62
C62
C62
36
0.1
0.3
0.20
0.20
1.0
8.5 × 1010


Comparative Example 63
C63
C63
33
10.5
31.8
0.20
0.20
1.0
6.5 × 1011


Comparative Example 64
C64
C64
18
1.6
8.9
0.20
0.20
1.0
5.0 × 1013


Comparative Example 65
C65
C65
51
5.5
10.8
0.20
0.20
1.0
3.0 × 108 


Comparative Example 66
C66
C66
36
—
—
0.20
—
—
8.5 × 1010


Comparative Example 67
C67
C67
36
0.03
0.1
0.20
0.20
1.0
8.5 × 1010


Comparative Example 68
C68
C68
50
0.03
0.1
0.20
0.20
1.0
4.5 × 108 


Comparative Example 69
C69
C69
30
16.2
54
0.20
0.20
1.0
9.0 × 1011


Comparative Example 70
C70
C70
45
17.1
38
0.20
0.20
1.0
2.0 × 109 


Comparative Example 71
C71
C71
36
0.1
0.3
0.20
0.20
1.0
8.5 × 1010


Comparative Example 72
C72
C72
33
10.5
31.8
0.20
0.20
1.0
6.5 × 1011


Comparative Example 73
C73
C73
40
6.1
15.3
0.20
0.20
1.0
6.7 × 1010


Comparative Example 74
C74
C74
36
4.7
13.1
0.20
0.20
1.0
8.5 × 1010


Comparative Example 75
C75
C75
36
4.3
11.9
0.20
0.20
1.0
8.5 × 1010


Comparative Example 76
C76
C76
42
—
—
0.20
—
—
7.0 × 108 


Comparative Example 77
C77
C77
37
4.7
12.7
0.20
0.20
1.0
9.0 × 108 


Comparative Example 78
C78
C78
20
17
85
0.20
0.20
1.0
1.0 × 1014


Comparative Example 79
C79
C79
18
26
144
0.20
0.20
1.0
1.0 × 1014


Comparative Example 80
C80
C80
42
—
—
0.03
—
—
7.7 × 1010


Comparative Example 81
C81
C81
47
—
—
0.055
—
—
8.0 × 108 


Comparative Example 82
C82
C82
47
—
—
0.07
—
—
8.0 × 108 


Comparative Example 83
C83
C83
48
—
—
0.065
—
—
7.5 × 108 









(Repeating Paper-Feeding Test of Electrophotographic Photosensitive Member)

Electrophotographic photosensitive members 1 to 115 and C1 to C83 for a repeating paper-feeding test were each installed on a laser beam printer (trade name: LBP7200C, manufactured by CANON KABUSHIKI KAISHA) and subjected to a repeating paper-feeding test in a low-temperature and low-humidity (15° C./10% RH) environment for image evaluation. In the printing operation of the repeating paper-feeding test, a text image with a printing ratio of 2% was output on 3000 sheets of letter-size paper in an intermittent mode.
A sample (half-tone image of a similar knight jump pattern) for image evaluation was output at each of the times of starting of the repeating paper-feeding test, after the completion of image output of 1500 sheets, and after the completion of image output of 3000 sheets. The criteria of evaluating images are as follows:
A: No image defect due to occurrence of current leakage was observed in the image,
B: A small black spot due to occurrence of current leakage was observed in the image,
C: A large black spot due to occurrence of current leakage was observed in the image,
D: A large black spot and a short horizontal black streak due to occurrence of current leakage were observed in the image, and
E: A long horizontal black streak due to occurrence of current leakage was observed in the image.
The charged potential (dark portion potential) and the exposure potential (light portion potential) were measured after the output of the samples for image evaluation at the times of starting of the repeating paper-feeding test and after the completion of image output of 3000 sheets. The measurement of potentials was performed using one white solid image and one black solid image. The variation amount in dark portion potential, ΔVd (=|Vd′|−|Vd|), which is the difference between the dark portion potential Vd′ after the completion of image output of 3000 sheets and the dark portion potential Vd at the beginning (at the time of starting of the repeating paper-feeding test), was determined. The variation amount in light portion potential, ΔVl (=|Vl′|−|Vl|), which is the difference between the light portion potential Vl′ after the completion of image output of 3000 sheets and the light portion potential Vl at the beginning (at the time of starting of the repeating paper-feeding test), was determined. The results are shown in Tables 10 and 11.










TABLE 10









Leakage
















After
After




Electro-
At starting
completion
completion



photographic
of paper-
of image
of image



photosensitive
feeding
output on
output on
Variation amount in potential [V]













Example
member
test
1500 sheets
3000 sheets
ΔVd
ΔVl
















1
1
A
A
A
+10
+25


2
2
A
A
A
+15
+30


3
3
A
A
A
+15
+30


4
4
A
B
B
+15
+30


5
5
A
A
A
+10
+15


6
6
A
A
A
+8
+10


7
7
A
A
A
+8
+10


8
8
A
A
A
+10
+20


9
9
A
A
A
+10
+20


10
10
A
A
A
+10
+15


11
11
A
A
A
+8
+10


12
12
A
A
B
+10
+15


13
13
A
A
A
+10
+15


14
14
A
A
A
+10
+15


15
15
A
A
B
+10
+15


16
16
A
A
A
+10
+15


17
17
A
A
A
+10
+15


18
18
A
A
A
+10
+25


19
19
A
A
A
+10
+25


20
20
A
A
A
+15
+30


21
21
A
A
A
+15
+30


22
22
A
B
B
+15
+30


23
23
A
A
A
+10
+15


24
24
A
A
A
+8
+10


25
25
A
A
A
+8
+10


26
26
A
A
A
+10
+20


27
27
A
A
A
+10
+20


28
28
A
A
A
+10
+15


29
29
A
A
A
+8
+10


30
30
A
A
B
+10
+15


31
31
A
A
A
+10
+15


32
32
A
A
A
+10
+15


33
33
A
A
B
+10
+15


34
34
A
A
A
+10
+15


35
35
A
A
A
+10
+15


36
36
A
A
A
+10
+25


37
37
A
A
A
+10
+25


38
38
A
A
A
+15
+30


39
39
A
A
A
+15
+30


40
40
A
B
B
+15
+30


41
41
A
A
A
+10
+15


42
42
A
A
A
+8
+10


43
43
A
A
A
+8
+10


44
44
A
A
A
+10
+20


45
45
A
A
A
+10
+20


46
46
A
A
A
+10
+15


47
47
A
A
A
+8
+10


48
48
A
A
B
+10
+15


49
49
A
A
A
+10
+15


50
50
A
A
A
+10
+15


51
51
A
A
B
+10
+15


52
52
A
A
A
+10
+15


53
53
A
A
A
+10
+15


54
54
A
A
A
+10
+25


55
55
A
B
B
+20
+35


56
56
A
A
A
+10
+20


57
57
A
A
A
+10
+20


58
58
A
A
A
+10
+15


59
59
A
A
A
+10
+20


60
60
A
A
A
+10
+20


61
61
A
A
A
+10
+15


62
62
A
A
A
+10
+15


63
63
A
A
B
+10
+20


64
64
A
A
A
+10
+20


65
65
A
A
A
+10
+20


66
66
A
A
B
+10
+20


67
67
A
B
B
+20
+35


68
68
A
A
A
+10
+20


69
69
A
A
A
+10
+20


70
70
A
A
A
+10
+15


71
71
A
A
A
+10
+20


72
72
A
A
A
+10
+20


73
73
A
A
A
+10
+15


74
74
A
A
A
+10
+15


75
75
A
A
B
+10
+20


76
76
A
A
A
+10
+20


77
77
A
A
A
+10
+20


78
78
A
A
B
+10
+20


79
79
A
B
B
+20
+35


80
80
A
A
A
+10
+20


81
81
A
A
A
+10
+20


82
82
A
A
A
+10
+15


83
83
A
A
A
+10
+20


84
84
A
A
A
+10
+20


85
85
A
A
A
+10
+15


86
86
A
A
A
+10
+15


87
87
A
A
B
+10
+20


88
88
A
A
A
+10
+20


89
89
A
A
A
+10
+20


90
90
A
A
B
+10
+20


91
91
A
B
B
+10
+35


92
92
A
A
A
+10
+25


93
93
A
A
A
+10
+25


94
94
A
A
A
+10
+20


95
95
A
A
A
+10
+25


96
96
A
A
A
+15
+30


97
97
A
A
A
+15
+20


98
98
A
A
A
+15
+20


99
99
A
B
B
+10
+25


100
100
A
A
A
+10
+25


101
101
A
A
A
+10
+25


102
102
A
B
B
+10
+25


103
103
A
B
B
+10
+35


104
104
A
A
A
+10
+30


105
105
A
A
A
+10
+30


106
106
A
A
A
+10
+25


107
107
A
A
A
+10
+30


108
108
A
A
A
+15
+35


109
109
A
A
A
+15
+25


110
110
A
A
A
+15
+25


111
111
A
B
B
+10
+30


112
112
A
A
A
+10
+30


113
113
A
A
A
+10
+30


114
114
A
B
B
+10
+30


115
115
A
A
A
+10
+20



















TABLE 11









Leakage
















After
After




Electro-
At starting
completion
completion



photographic
of paper-
of image
of image












Comparative
photosensitive
feeding
output on
output on
Variation amount in potential [V]













Example
member
test
1500 sheets
3000 sheets
ΔVd
ΔVl
















1
C1 
A
A
A
+15
+50


2
C2 
B
B
B
+10
+10


3
C3 
C
C
C
+10
+15


4
C4 
B
C
C
+10
+15


5
C5 
C
C
C
+10
+10


6
C6 
A
A
A
+15
+55


7
C7 
A
A
A
+15
+45


8
C8 
B
C
C
+10
+15


9
C9 
A
A
A
+10
+50


10
C10
A
A
A
+15
+55


11
C11
B
B
C
+10
+10


12
C12
C
C
D
+10
+15


13
C13
C
C
C
+10
+15


14
C14
C
C
D
+10
+10


15
C15
A
A
A
+15
+60


16
C16
A
A
A
+15
+50


17
C17
C
C
C
+10
+15


18
C18
A
A
A
+10
+55


19
C19
A
A
A
+15
+50


20
C20
B
B
B
+10
+10


21
C21
C
C
C
+10
+15


22
C22
B
C
C
+10
+15


23
C23
C
C
C
+10
+10


24
C24
A
A
A
+15
+55


25
C25
A
A
A
+15
+45


26
C26
B
C
C
+10
+15


27
C27
A
A
A
+10
+50


28
C28
A
A
A
+15
+55


29
C29
B
B
C
+10
+10


30
C30
C
C
D
+10
+15


31
C31
C
C
C
+10
+15


32
C32
C
C
D
+10
+10


33
C33
A
A
A
+15
+60


34
C34
A
A
A
+15
+50


35
C35
C
C
C
+10
+15


36
C36
A
A
A
+10
+55


37
C37
A
A
A
+15
+50


38
C38
B
B
B
+10
+10


39
C39
C
C
C
+10
+15


40
C40
B
C
C
+10
+15


41
C41
C
C
C
+10
+10


42
C42
A
A
A
+15
+55


43
C43
A
A
A
+15
+45


44
C44
B
C
C
+10
+15


45
C45
A
A
A
+10
+50


46
C46
A
A
A
+15
+55


47
C47
B
B
C
+10
+10


48
C48
C
C
D
+10
+15


49
C49
C
C
C
+10
+15


50
C50
C
C
D
+10
+10


51
C51
A
A
A
+15
+60


52
C52
A
A
A
+15
+50


53
C53
C
C
C
+10
+15


54
C54
A
A
A
+10
+55


55
C55
A
A
A
+15
+55


56
C56
B
B
C
+10
+10


57
C57
C
C
D
+10
+15


58
C58
C
C
C
+10
+15


59
C59
C
C
D
+10
+10


60
C60
A
A
A
+15
+60


61
C61
A
A
A
+15
+50


62
C62
C
C
C
+10
+15


63
C63
A
A
A
+10
+55


64
C64
A
A
A
+15
+60


65
C65
B
C
C
+10
+10


66
C66
C
D
D
+10
+15


67
C67
C
C
D
+10
+15


68
C68
C
D
D
+10
+10


69
C69
A
A
A
+15
+65


70
C70
A
A
A
+15
+55


71
C71
C
C
D
+10
+15


72
C72
A
A
A
+10
+60


73
C73
B
B
B
+10
+20


74
C74
B
B
B
+10
+20


75
C75
B
B
B
+10
+20


76
C76
E
E
E
+8
+10


77
C77
D
E
E
+8
+10


78
C78
A
A
A
+20
+100


79
C79
A
A
A
+20
+100


80
C80
C
C
D
+10
+20


81
C81
C
D
D
+10
+20


82
C82
C
D
D
+10
+20


83
C83
C
D
D
+10
+20









(Needle Breakdown Voltage Test of Electrophotographic Photosensitive Member)

Electrophotographic photosensitive members 116 to 230 and C84 to C166 for needle breakdown voltage test were subjected to the following needle breakdown voltage test.
FIG. 2 shows a needle breakdown voltage tester. The needle breakdown voltage test was conducted in an ordinary temperature and ordinary humidity (23° C./50% RH) environment.
An electrophotographic photosensitive member 1401 was placed on a fixing table 1402 and was fixed at both ends so that it will not move. The tip of a needle electrode 1403 was brought into contact with the surface of the electrophotographic photosensitive member 1401. The needle electrode 1403 was connected to a power source 1404 for applying a voltage to the needle electrode 1403 and connected to an ammeter 1405 for measuring an electric current. A portion 1406 of the electrophotographic photosensitive member 1401 being in contact with the support was earth-connected. The voltage applied from the needle electrode 1403 was increased from 0 V by 10 V per every 2 seconds to cause current leakage inside the electrophotographic photosensitive member 1401 being in contact with the tip of the needle electrode 1403. The voltage at which the amperage measured with the ammeter 1405 was 10 times or more the amperage at the voltage applied immediately before (the voltage lower than the needle breakdown voltage value by 10 V) was defined as a needle breakdown voltage value. This measurement was conducted at five different points of the surface of the electrophotographic photosensitive member 1401, and the average value was defined as the needle breakdown voltage value of the measuring object, the electrophotographic photosensitive member 1401. The results are shown in Tables 12 and 13.









TABLE 12






Electro-
Needle



photographic
breakdown



photosensitive
voltage


Example
member
[−V]

















1
116
4500


2
117
4500


3
118
4500


4
119
3500


5
120
4100


6
121
4000


7
122
4000


8
123
4100


9
124
4100


10
125
4100


11
126
4000


12
127
3900


13
128
4100


14
129
4000


15
130
3900


16
131
4000


17
132
4000


18
133
4200


19
134
4500


20
135
4500


21
136
4500


22
137
3500


23
138
4100


24
139
4000


25
140
4000


26
141
4100


27
142
4100


28
143
4100


29
144
4000


30
145
3900


31
146
4100


32
147
4000


33
148
3900


34
149
4000


35
150
4000


36
151
4200


37
152
4500


38
153
4500


39
154
4500


40
155
3500


41
156
4100


42
157
4000


43
158
4000


44
159
4100


45
160
4100


46
161
4100


47
162
4000


48
163
3900


49
164
4100


50
165
4000


51
166
3900


52
167
4000


53
168
4000


54
169
4200


55
170
3400


56
171
3900


57
172
3900


58
173
3800


59
174
3900


60
175
3900


61
176
3800


62
177
3800


63
178
3700


64
179
3900


65
180
3900


66
181
3700


67
182
3400


68
183
3900


69
184
3900


70
185
3800


71
186
3900


72
187
3900


73
188
3800


74
189
3800


75
190
3700


76
191
3900


77
192
3900


78
193
3700


79
194
3400


80
195
3900


81
196
3900


82
197
3800


83
198
3900


84
199
3900


85
200
3800


86
201
3800


87
202
3700


88
203
3900


89
204
3900


90
205
3700


91
206
3300


92
207
3800


93
208
3800


94
209
3700


95
210
3800


96
211
3900


97
212
3700


98
213
3700


99
214
3300


100
215
3800


101
216
3800


102
217
3300


103
218
3200


104
219
3700


105
220
3700


106
221
3600


107
222
3700


108
223
3800


109
224
3600


110
225
3600


111
226
3200


112
227
3700


113
228
3700


114
229
3200


115
230
4000


















TABLE 13






Electro-
Needle



photographic
breakdown


Comparative
photosensitive
voltage


Example
member
[−V]

















1
C84 
4500


2
C85 
3000


3
C86 
1500


4
C87 
2000


5
C88 
1500


6
C89 
4100


7
C90 
4000


8
C91 
2000


9
C92 
4100


10
C93 
4400


11
C94 
2900


12
C95 
1400


13
C96 
1900


14
C97 
1400


15
C98 
4000


16
C99 
3900


17
C100
1900


18
C101
4000


19
C102
4500


20
C103
3000


21
C104
1500


22
C105
2000


23
C106
1500


24
C107
4100


25
C108
4000


26
C109
2000


27
C110
4100


28
C111
4400


29
C112
2900


30
C113
1400


31
C114
1900


32
C115
1400


33
C116
4000


34
C117
3900


35
C118
1900


36
C119
4000


37
C120
4500


38
C121
3000


39
C122
1500


40
C123
2000


41
C124
1500


42
C125
4100


43
C126
4000


44
C127
2000


45
C128
4100


46
C129
4400


47
C130
2900


48
C131
1400


49
C132
1900


50
C133
1400


51
C134
4000


52
C135
3900


53
C136
1900


54
C137
4000


55
C138
4300


56
C139
2800


57
C140
1300


58
C141
1800


59
C142
1300


60
C143
3900


61
C144
3800


62
C145
1800


63
C146
3900


64
C147
4200


65
C148
2700


66
C149
1200


67
C150
1700


68
C151
1200


69
C152
3800


70
C153
3700


71
C154
1700


72
C155
3800


73
C156
3000


74
C157
3000


75
C158
3000


76
C159
500


77
C160
800


78
C161
4600


79
C162
4600


80
C163
1200


81
C164
1000


82
C165
1000


83
C166
1000









While the present invention has been described with reference to exemplary embodiments, it is to be understood that the invention is not limited to the disclosed exemplary embodiments. The scope of the following claims is to be accorded the broadest interpretation so as to encompass all such modifications and equivalent structures and functions.
This application claims the benefit of Japanese Patent Application No. 2014-033340 filed Feb. 24, 2014 and No. 2015-019188 filed Feb. 3, 2015, which are hereby incorporated by reference herein in their entirety.

## Claims

1. An electrophotographic photosensitive member comprising:
a support;
a conductive layer on the support; and
a photosensitive layer on the conductive layer, wherein
the conductive layer comprises a binder material, a first particle, and a second particle;
the first particle is composed of a core particle coated with aluminum-doped zinc oxide;
the second particle is composed of the same material as that of the core particle of the first particle and is not coated with an inorganic material or an organic material;
a content of the first particle in the conductive layer is 20% by volume or more and 50% by volume or less based on a total volume of the conductive layer; and
a content of the second particle in the conductive layer is 0.1% by volume or more and 15% by volume or less based on the total volume of the conductive layer, and 0.5% by volume or more and 30% by volume or less based on the volume of the first particle in the conductive layer.

2. The electrophotographic photosensitive member according to claim 1, wherein the core particle of the first particle and the second particle are titanium oxide particles.

3. The electrophotographic photosensitive member according to claim 1, wherein the core particle of the first particle and the second particle are zinc oxide particles.

4. The electrophotographic photosensitive member according to claim 1, wherein the core particle of the first particle and the second particle are tin oxide particles.

5. The electrophotographic photosensitive member according to claim 1, wherein the content of the second particle in the conductive layer is 1% by volume or more and 20% by volume or less based on the volume of the first particle.

6. The electrophotographic photosensitive member according to claim 1, wherein the first particle and the second particle in the conductive layer respectively have an average primary particle diameter (D1) and an average primary particle diameter (D2), and a ratio (D1/D2) of the average primary particle diameter D1 to the average primary particle diameter D2 is 0.7 or more and 1.3 or less.

7. The electrophotographic photosensitive member according to claim 1, wherein the binder material is a curable resin.

8. The electrophotographic photosensitive member according to claim 1, wherein the first particle has an average primary particle diameter (D1) of 0.10 μm or more and 0.45 μm or less.

9. The electrophotographic photosensitive member according to claim 1, wherein the conductive layer has a volume resistivity of 1.0×108 Ω·cm or more and 5.0×1012 Ω·cm or less.

10. A process cartridge integrally supporting the electrophotographic photosensitive member according to claim 1 and at least one selected from the group consisting of charging devices, developing devices, and cleaning devices and being detachably attachable to an electrophotographic apparatus main body.

11. An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 1, a charging device, an exposing device, a developing device, and a transferring device.

12. An electrophotographic photosensitive member comprising:
a support;
a conductive layer on the support; and
a photosensitive layer on the conductive layer, wherein
the conductive layer comprises a binder material, a first particle, and a second particle;
the first particle is composed of a core particle coated with oxygen-deficient zinc oxide;
the second particle is composed of the same material as that of the core particle of the first particle and is not coated with an inorganic material or an organic material;
a content of the first particle in the conductive layer is 20% by volume or more and 50% by volume or less based on a total volume of the conductive layer; and
a content of the second particle in the conductive layer is 0.1% by volume or more and 15% by volume or less based on the total volume of the conductive layer, and 0.5% by volume or more and 30% by volume or less based on the volume of the first particle in the conductive layer.

13. The electrophotographic photosensitive member according to claim 12, wherein the core particle of the first particle and the second particle are titanium oxide particles.

14. The electrophotographic photosensitive member according to claim 12, wherein the core particle of the first particle and the second particle are zinc oxide particles.

15. The electrophotographic photosensitive member according to claim 12, wherein the core particle of the first particle and the second particle are tin oxide particles.

16. The electrophotographic photosensitive member according to claim 12, wherein the content of the second particle in the conductive layer is 1% by volume or more and 20% by volume or less based on the volume of the first particle.

17. The electrophotographic photosensitive member according to claim 12, wherein the first particle and the second particle in the conductive layer respectively have an average primary particle diameter (D1) and an average primary particle diameter (D2), and a ratio (D1/D2) of the average primary particle diameter D1 to the average primary particle diameter D2 is 0.7 or more and 1.3 or less.

18. The electrophotographic photosensitive member according to claim 12, wherein the binder material is a curable resin.

19. The electrophotographic photosensitive member according to claim 12, wherein the first particle has an average primary particle diameter (D1) of 0.10 μm or more and 0.45 μm or less.

20. The electrophotographic photosensitive member according to claim 12, wherein the conductive layer has a volume resistivity of 1.0×108 Ω·cm or more and 5.0×1012 Ω·cm or less.

21. A process cartridge integrally supporting the electrophotographic photosensitive member according to claim 12 and at least one selected from the group consisting of charging devices, developing devices, and cleaning devices and being detachably attachable to an electrophotographic apparatus main body.

22. An electrophotographic apparatus comprising the electrophotographic photosensitive member according to claim 12, a charging device, an exposing device, a developing device, and a transferring device.