JP2009069678A - Electrophotographic photoreceptor, process cartridge and image forming apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor, a process cartridge and an image forming apparatus suppressing increase in a residual voltage, suppressing an afterimage (ghost) phenomenon caused by remainder of previous history, and stably giving favorable picture quality for a long period of time. <P>SOLUTION: The electrophotographic photoreceptor comprises a base layer 2 and a photosensitive layer 3 successively stacked on a conductive support body 1, wherein the base layer 2 is composed of two or more layers, and each of the two or more layers of the base layer 2 contains metal oxide particles. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an electrophotographic photosensitive member, a process cartridge, and an image forming apparatus.

  An electrophotographic image forming apparatus can obtain high-speed and high-quality printing, and is used in image forming apparatuses such as copying machines, laser printers, and LED printers.

  As a conventional electrophotographic photosensitive member used in these image forming apparatuses, a photosensitive member in which a photosensitive layer using a photoconductive material is formed on a conductive support is known. Conventionally, in this photoreceptor, the conductive support and the photosensitive layer are used to improve the chargeability, improve the adhesion between the support and the photosensitive layer, conceal defects on the support surface, reduce image defects due to pinhole leakage, etc. An undercoat layer is often provided between the two.

  Materials for forming this undercoat layer include thermoplastic resins such as polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl methyl ether, polyamide, thermoplastic polyester, phenoxy resin, casein, gelatin, nitrocellulose, and polyimide. In addition, thermosetting resins such as polyethyleneimine, epoxy resin, melamine resin, phenol resin, and polyurethane resin are known.

  Also, those obtained by blending a conductive polymer with the resin of the undercoat layer (Japanese Patent Publication No. 2-059458), and those obtained by dispersing conductive powder in the resin of the undercoat layer (Japanese Patent Publication No. 2-059459) Etc. have been proposed.

On the other hand, many proposals have been made to anodize the conductive support in order to improve the non-uniformity of the surface of the conductive support and to improve the chargeability. There have also been many proposals for improving the anodizing treatment.
For example, Japanese Patent Application Laid-Open Nos. 64-29852 and 4-278957 propose the provision of a hydrated aluminum oxide layer on an aluminum support.
For example, Japanese Patent Laid-Open No. 6-3845 proposes limiting the diameter of the crystallized substance on the surface of the aluminum support and the bare area ratio.
For example, Japanese Patent Laid-Open No. 62-287259 proposes that a silane coupling agent is reacted with hydrated aluminum oxide to perform a silylation treatment.

Further, only a layer containing conductive powder is formed as an undercoat layer on a conductive support layer, and a photosensitive member having a configuration in which both the blocking function and the resistance adjusting function described above are included in this layer is formed. There is also a method (Japanese Patent Laid-Open No. 2003-084472).
Japanese Patent Publication No. 2-059458 Japanese Patent Publication No. 2-059459 Japanese Unexamined Patent Publication No. 64-29852 JP-A-4-278957 JP-A-6-3845 JP-A-62-287259 Japanese Patent Laid-Open No. 2003-084472

  An object of the present invention is to suppress an increase in the residual voltage, suppress an afterimage phenomenon (ghost) caused by a previous history remaining, and to stably obtain a good image quality over a long period of time, a process cartridge, and An image forming apparatus is provided.

The above problem is solved by the following means. That is,
The invention according to claim 1
An undercoat layer and a photosensitive layer are sequentially laminated on a conductive support;
An electrophotographic photoreceptor, wherein the undercoat layer is composed of two or more layers, and each of the two or more undercoat layers contains metal oxide particles.

The invention according to claim 2
Of the two or more undercoat layers, the secondary particle diameter of the metal oxide particles contained in the undercoat layer closest to the conductive support is A (1), the lowest farthest from the conductive support. 2. The electrophotographic photosensitive member according to claim 1, wherein A (1) <A (2) when the secondary particle diameter of the metal oxide particles contained in the pulling layer is A (2). Is the body.

The invention according to claim 3
Of the two or more undercoat layers, the secondary particle diameter of the metal oxide particles contained in the undercoat layer closest to the conductive support is A (1), the lowest farthest from the conductive support. 3. A (1) ≦ 0.9 × A (2), where A (2) is the secondary particle diameter of the metal oxide particles contained in the pulling layer. The electrophotographic photoreceptor described in 1.

The invention according to claim 4
4. The electrophotographic photosensitive member according to claim 1, wherein the two or more undercoat layers satisfy the following formulas (1) to (3): 5.
Formula (1): a (1)> a (2)>... A (n-1)> a (n)
Formula (2): b (1) <b (2) <... B (n−1) <b (n)
Formula (3): c (1)> c (2)>... C (n-1)> c (n)
(However, in the formulas (1) to (3), a (1), a (2),..., A (n-1), a (n) are the first from the closest to the conductive support. 2,..., N-1 and n, the thickness of the effective photosensitive region center of the undercoat layer, b (1), b (2),... B (n−1), b (N) is the effective photosensitive region end film thickness of the first, second,..., N−1, nth subbing layer from the side closer to the conductive support, and c (1), c (2), ... c (n-1), c (n) are the volumes of the first, second, ... n-1st, nth undercoat layers from the side closer to the conductive support. (Where n represents the total number of undercoat layers and is an integer of 2 or more)

The invention according to claim 5
The volume resistivity of the undercoat layer is 1.0 × 10 ¹⁵ (Ω · cm) ≧ c (1)> c (2)>... C (n−1)> c (n) ≧ 1.0 The electrophotographic photosensitive member according to claim 4, wherein x 10 ⁸ (Ω · cm) is satisfied.

The invention according to claim 6
6. The electrophotographic photoreceptor according to claim 1, wherein the metal oxide particles contained in the two or more undercoat layers contain the same metal.

The invention according to claim 7 provides:
7. The electrophotographic photoreceptor according to claim 1, wherein the metal oxide particles contained in the two or more undercoat layers are subjected to silane coupling treatment.

The invention according to claim 8 provides:
The electrophotographic photosensitive member according to claim 1, wherein two or more undercoat layers have the same composition.

The invention according to claim 9 is:
The electrophotographic photosensitive member according to any one of claims 1 to 8,
Selected from charging means for charging the electrophotographic photosensitive member, electrostatic latent image forming means for exposing the electrophotographic photosensitive member to form an electrostatic latent image, and developing means for developing the electrostatic latent image with toner. And one kind
And a process cartridge that is detachably attached to the main body of the image forming apparatus.

The invention according to claim 10 is:
The electrophotographic photosensitive member according to any one of claims 1 to 8,
Charging means for charging the electrophotographic photoreceptor;
Electrostatic latent image forming means for exposing the electrophotographic photosensitive member to form an electrostatic latent image;
Developing means for developing the electrostatic latent image with toner;
Transfer means for transferring the toner image to a transfer medium;
An image forming apparatus comprising:

  According to the present invention, an electrophotographic photosensitive member, a process cartridge, and a process cartridge that can suppress an increase in residual voltage, suppress an afterimage phenomenon (ghost) caused by a previous history remaining, and stably obtain a good image quality over a long period of time. An image forming apparatus can be provided.

  Hereinafter, embodiments of the present invention will be described in detail.

(Electrophotographic photoreceptor)
The electrophotographic photosensitive member according to the embodiment is formed by sequentially laminating an undercoat layer and a photosensitive layer on a conductive support, the undercoat layer is composed of two or more layers, and the two or more undercoat layers. It is characterized by containing metal oxide particles.

  In the electrophotographic photosensitive member according to the embodiment, an increase in the residual voltage is suppressed, and an image defect such as fogging is suppressed together with an afterimage phenomenon (ghost) caused by the previous history remaining, so that a good image quality can be stably provided over a long period of time. can get. Although the details of this mechanism are unknown, the presumed mechanism is as follows. There are various functions of the undercoat layer, such as improving the adhesion between the conductive support and the photosensitive layer, reducing the occurrence of leakage due to foreign object sticking, etc., but the undercoat layer is composed of two or more layers, and the undercoat layer is composed of two or more layers. By including metal oxide particles in each of them, a conductive layer to the conductive support is provided by an undercoat layer close to the conductive support, thereby suppressing an increase in residual potential and being far from the conductive support. The undercoat layer has many conductive paths at the interface of the photosensitive layer (charge generation layer), and promotes the extraction of charges from the photosensitive layer (charge generation layer). For this reason, it is considered that an increase in the residual voltage is suppressed and an afterimage phenomenon (ghost) caused by the previous history remaining is suppressed, so that good image quality can be stably obtained over a long period of time.

  Hereinafter, an electrophotographic photosensitive member according to an embodiment will be described with reference to the drawings. FIG. 1 is a schematic cross-sectional view showing an electrophotographic photosensitive member according to an embodiment. 2 to 4 are schematic cross-sectional views showing an electrophotographic photosensitive member according to another embodiment. An electrophotographic photoreceptor 7 shown in FIG. 1 includes a conductive base material 1, an undercoat layer 2 formed on the base material, and a photosensitive layer 3 formed on the undercoat layer 2. Has been. An electrophotographic photoreceptor 7 shown in FIG. 2 has a configuration in which the photosensitive layer 3 in the electrophotographic photoreceptor shown in FIG. 1 has a two-layer structure of a charge generation layer 4 and a charge transport layer 5. Further, the electrophotographic photosensitive member 7 shown in FIGS. 3 to 4 has a configuration in which a protective layer 6 is further provided on the photosensitive layer 3 in the electrophotographic photosensitive member shown in FIGS.

Hereinafter, each member will be described. Note that the reference numerals are omitted.
First, as the conductive support, aluminum, copper, gold, silver, platinum, palladium, titanium, nickel-chromium, aluminum, copper, iron, nickel, and other metal drums, and glass, on a plastic cylindrical substrate. It is possible to use a known drum-like material which is conductively treated by depositing a metal such as stainless steel or barrel-indium, or depositing a conductive metal compound such as indium oxide or tin oxide, or laminating a metal foil. . Here, “conductive” means that the volume resistivity is less than 10 ¹³ Ωcm.

  Next, the undercoat layer will be described. The undercoat layer is composed of two or more layers. Each of the two or more undercoat layers 2 contains metal oxide particles.

  Of the two or more undercoat layers, the secondary particle diameter of the metal oxide particles contained in the undercoat layer closest to the conductive support is A (1), and is contained in the undercoat layer farthest from the conductive support. When the secondary particle diameter of the metal oxide particles is A (2), it is desirable that A (1) <A (2), and preferably A (1) ≦ 0.9 × A (2) More preferably, A (1) ≦ 0.7 × A (2). In particular, the secondary particle diameter of the metal oxide particles contained in the undercoat layer is preferably configured to increase from the undercoat layer closest to the conductive support to the upper layer. From the viewpoint of securing conductivity, the lower limit of A (1) is 0.4 × A (2) (that is, 0.4 × A (2) ≦ A (1)).

  A ghost is suppressed more effectively because the secondary particle diameter of the metal oxide particles contained in each of the two or more undercoat layers satisfies the above relationship. This is presumed to be due to the following reasons. By including metal oxide particles with a small secondary particle diameter in the undercoat layer closest to the conductive support, it has more conduction paths to the conductive support and further suppresses the increase in residual potential. It is done. On the other hand, by adding metal oxide particles having a large secondary particle size to the undercoat layer farthest from the conductive support, that is, the undercoat layer adjacent to the photosensitive layer (charge generation layer), the photosensitive layer (charge generation layer) ) The interface has a larger number of conduction paths, and the charge extraction from the photosensitive layer (charge generation layer) is further promoted. For this reason, it is thought that a ghost is suppressed more effectively.

  Here, the secondary particle diameter A (1) of the metal oxide particles contained in the undercoat layer closest to the conductive support is preferably 0.05 μm or more and 10 μm or less, and more preferably 0.07 μm. It is not less than 1 μm and more desirably not less than 0.07 μm and not more than 0.3 μm.

  Here, the measuring method of the secondary particle diameter can be performed using a transmission electron microscope. That is, the metal oxide fine particles are dispersed together with a desired binder resin by a desired method, applied onto a desired substrate, and dried to obtain a coating film. After the obtained coating film is cut out into small pieces, Pt—Pd is deposited to a thickness of 2 nm (target) for embedding and curing in a resin for an electron microscope for surface retention and identification. After the cross-section is prepared by a microtome, the sample is fixed to the SEM sample stage and Pt-Pd is deposited by 5 nm (target) for imparting conductivity to obtain a sample. A cross-sectional image of the film is taken at an appropriate acceleration voltage (preferably 5 to 20 kV), and the particle diameter is measured from the obtained image. At this time, it is preferable to adjust and image a plurality of cross sections and average the obtained individual particle diameters to obtain a final secondary particle diameter. The number of particles to be measured depends on the particle size distribution of the particles, but it is desirable to measure approximately 20 or more.

  Each undercoat layer may contain a mixture of two or more kinds of metal oxide particles such as those having different surface treatments or particles having different particle diameters. In that case, said A (1) and A (2) are the average secondary particle diameter of the metal oxide particle contained in each layer. This average secondary particle diameter is obtained by adjusting a coating film containing two or more kinds of metal oxide particles in advance and measuring by the above method.

Further, it is desirable that two or more undercoat layers satisfy the following formulas (1) to (3).
Formula (1): a (1)> a (2)>... A (n-1)> a (n)
Formula (2): b (1) <b (2) <... B (n−1) <b (n)
Formula (3): c (1)> c (2)>... C (n-1)> c (n)
(However, in the formulas (1) to (3), a (1), a (2),..., A (n-1), a (n) are the first from the closest to the conductive support. 2,..., N-1 and n, the thickness of the effective photosensitive region center of the undercoat layer, b (1), b (2),... B (n−1), b (N) is the effective photosensitive region end film thickness of the first, second,..., N−1, nth subbing layer from the side closer to the conductive support, and c (1), c (2), ... c (n-1), c (n) are the volumes of the first, second, ... n-1st, nth undercoat layers from the side closer to the conductive support. (Where n represents the total number of undercoat layers and is an integer of 2 or more)

In particular, the volume resistivity of the undercoat layer is 1.0 × 10 ¹⁵ (Ω · cm) ≧ c (1)> c (2)>... C (n−1)> c (n) ≧ 1. It is desirable to satisfy 0 × 10 ⁸ (Ω · cm),
More desirably, 1.0 × 10 ¹⁴ (Ω · cm) ≧ c (1)> c (2)>... C (n−1)> c (n) ≧ 1.0 × 10 ¹⁰ (Ω · cm)
It is.

  By satisfying the above formulas (1) to (3), it is possible to suppress image quality failure such as ghosts and to obtain good image quality in-plane density uniformity (hereinafter referred to as density in-plane uniformity as appropriate). Although the details are unknown, the presumed mechanism is as follows. Each subbing layer from the central portion (the central portion in the conductive support axial direction) to the end portion (the end in the conductive axial direction) of the effective photosensitive region of the electrophotographic photosensitive member so as to satisfy the expressions (1) and (2) The film thickness is changed. However, the volume resistivity of each undercoat layer satisfies the formula (3). At this time, the undercoat layer having a large volume resistivity is thick at the center of the effective photosensitive region, and the undercoat layer having a small volume resistivity is thickened toward the end. Therefore, the total volume resistivity of the entire undercoat layer is different between the central portion and the end portion of the effective photosensitive region, specifically, the composite volume resistivity is large at the central portion of the effective photosensitive region, and the combined volume resistivity at the end portion of the effective photosensitive region. The rate is reduced. Also, the change in the synthetic volume resistivity is continuous. Due to the change in the composite volume resistivity, the photosensitivity of the electrophotographic photosensitive member changes at the center and the edge of the effective photosensitive region. The lower the synthetic volume resistance of the entire undercoat layer, the higher the photosensitivity of the electrophotographic photosensitive member. The higher the combined volume resistance, the lower the photosensitivity, so that the end of the effective photosensitive region is relatively sensitive to the center. For this reason, it is possible to suppress a decrease in density at the end of the effective photosensitive region where the exposure energy is insufficient. Therefore, satisfying the above formulas (1) to (3) means that this state is realized in one electrophotographic photosensitive member, and image quality failure such as ghost is suppressed and good image quality is achieved. Density uniformity (hereinafter referred to as density in-plane uniformity).

Here, the effective photosensitive area means a photosensitive area of the electrophotographic photosensitive member corresponding to an exposure area necessary for forming an image on a desired paper size.
Further, the combined volume resistivity of the undercoat layer means a volume resistivity measured after forming a plurality of undercoat layers as described above. The composite volume resistivity of the undercoat layer may be a desired value, but is desirably 1.0 × 10 ⁸ (Ω · cm) or more and 1.0 × 10 ¹⁵ (Ω · cm) or less, and more desirably. Is 1.0 × 10 ¹⁰ (Ω · cm) or more and 1.0 × 10 ¹³ (Ω · cm) or less. When the combined volume resistivity is less than 1.0 × 10 ⁸ (Ω · cm), sufficient leakage resistance may not be obtained, and when it is greater than 1.0 × 10 ¹⁵ (Ω · cm) Concentration reproducibility may not be obtained during repeated use due to an increase in residual potential. By controlling the film thickness profile of each undercoat layer, it is possible to control the combined volume resistivity of the undercoat layer at the center and the end of the effective photosensitive region of the electrophotographic photoreceptor. The difference in the combined volume resistivity between the central portion and the end portion of the effective photosensitive region varies depending on the image forming apparatus, but generally a difference of 10 to 100 times is desirable. At this time, the combined volume resistance is larger in the central portion of the effective photosensitive area. If the difference is smaller than 10 times, the density reduction at the end of the effective photosensitive region may be remarkable, and if it exceeds 100 times, the density may increase at the edge.

The volume resistivity of the undercoat layer can be measured by a desired method. In this example, regarding the measurement of the undercoat layer formed on the conductive support, a φ1 mm gold electrode was used as the counter electrode, and 10 ⁷ V / m was applied in an environment of 22 ° C. and 55% RH. The volume resistance is obtained from the current value, and the volume resistivity is determined from the result and the thickness of the measurement sample.
Further, the synthetic volume resistivity can be measured in the same manner as in the above method, but a plurality of undercoat layers are formed in advance on a conductive support as a sample and measured.

  It is most desirable that the metal oxide particles contained in two or more undercoat layers contain the same metal. Here, that the metal oxide particles contain the same metal means that the metal elements constituting the metal oxide particles are the same. This facilitates resistance adjustment between two or more undercoat layers.

  Hereinafter, the metal oxide particles will be described in detail. Examples of the metal oxide particles include zinc oxide, titanium oxide, tin oxide alone, or a combination of these. In particular, zinc oxide and titanium oxide are preferable because of high electron mobility and good electrophotographic characteristics.

The metal oxide particles preferably have a powder resistance of about 10 ² Ω · cm to 10 ¹¹ Ω · cm (desirably 10 ⁴ Ω · cm to 10 ⁸ Ω · cm). This is because the undercoat layer needs to obtain an appropriate resistance for obtaining leak resistance. Among these, metal oxide particles such as the above-mentioned tin oxide, titanium oxide, and zinc oxide having the above resistance are preferable, and metal oxide particles of zinc oxide are particularly preferable. If the resistance value of the metal oxide particles is lower than the lower limit of the above range, sufficient leakage resistance cannot be obtained.

As the metal oxide particles, those having a specific surface area of 10 m ² / g or more are desirably used. Those having a specific surface area value of 10 m ² / g or less are likely to cause a decrease in chargeability, and it may be difficult to obtain good electrophotographic characteristics.

  The metal oxide particles are preferably subjected to a surface treatment with a silane coupling agent for the purpose of adjusting the resistance. In particular, as the silane coupling agent, a silane coupling agent having an amino group is desirable because it gives a good blocking property to the undercoat layer.

  Any silane coupling agent having an amino group can be used as long as it can obtain desired photoreceptor characteristics. Specific examples of the silane coupling agent having an amino group include γ-aminopropyltriethoxysilane, N-β- (aminoethyl) -γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ. Examples include, but are not limited to, aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, and the like. Moreover, 2 or more types of silane coupling agents can also be mixed and used. Examples of silane coupling agents that can be used in combination with the silane coupling agent having an amino group include vinyltrimethoxysilane, γ-methacryloxypropyl-tris (β-methoxyethoxy) silane, β- (3, 4-epoxycyclohexyl) ethyltrimethoxysilane, γ-glycidoxypropyltrimethoxysilane, vinyltriacetoxysilane, γ-mercaptopropyltrimethoxysilane, γ-aminopropyltriethoxysilane, N-β- (aminoethyl)- γ-aminopropyltrimethoxysilane, N-β- (aminoethyl) -γ-aminopropylmethylmethoxysilane, N, N-bis (β-hydroxyethyl) -γ-aminopropyltriethoxysilane, γ-chloropropyltri Examples include methoxysilane. The present invention is not limited to, et al.

  The amount of the silane coupling agent relative to the metal oxide particles can be arbitrarily set as long as desired electrophotographic characteristics can be obtained.

  Here, as long as the surface treatment method is a known method, any method can be used, but a dry method or a wet method can be used. When surface treatment is performed by a dry method, a silane coupling agent dissolved directly or in an organic solvent is added dropwise and sprayed with dry air or nitrogen gas while stirring the metal oxide particles with a mixer having a large shearing force. Is uniformly processed. The addition or spraying is preferably performed at a temperature below the boiling point of the solvent. When spraying at a temperature equal to or higher than the boiling point of the solvent, the solvent evaporates before being uniformly stirred, and the silane coupling agent is locally concentrated, which is not desirable because it is difficult to perform uniform processing. After addition or spraying, baking can be performed at 100 ° C. or higher. Baking can be carried out in an arbitrary range as long as the temperature and time allow the desired electrophotographic characteristics to be obtained. As a wet method, the metal oxide particles are stirred in a solvent, dispersed using an ultrasonic wave, a sand mill, an attritor, a ball mill, etc., added with a silane coupling agent solution and stirred or dispersed, and then the solvent is removed. Uniformly processed. The solvent removal method is distilled off by filtration or distillation. After removing the solvent, baking can be performed at 100 ° C. or higher. Baking can be carried out in an arbitrary range as long as the temperature and time allow the desired electrophotographic characteristics to be obtained. In the wet method, the water containing metal oxide particles can be removed before adding the surface treatment agent. For example, a method of removing with stirring and heating in the solvent used for the surface treatment, removing by azeotroping with the solvent. It is also possible to use a method of

  Next, other components of the undercoat layer will be described. The undercoat layer may contain a binder resin. As binder resins, vinyltrichlorosilane, vinyltrimethoxysilane, vinyltriethoxysilane, vinyltris-2-methoxyethoxysilane, vinyltriacetoxysilane, γ-glycidoxypropyltrimethoxysilane, γ-methacryloxypropyltrimethoxysilane, γ-aminopropyltriethoxysilane, γ-chloropropyltrimethoxysilane, γ-2-aminoethylaminopropyltrimethoxysilane, γ-mercapropropyltrimethoxysilane, γ-ureidopropyltriethoxysilane, β-3,4 -It can be used by containing a silane coupling agent such as epoxycyclohexyltrimethoxysilane. Furthermore, polyvinyl alcohol, polyvinyl methyl ether, poly-N-vinyl imidazole, polyethylene oxide, ethyl cellulose, methyl cellulose, ethylene-acrylic acid copolymer, polyamide, polyimide, casein, gelatin, polyethylene, conventionally used for the undercoat layer Known binder resins such as polyester, phenol resin, vinyl chloride-vinyl acetate copolymer, epoxy resin, polyvinyl pyrrolidone, polyvinyl pyridine, polyurethane, polyglutamic acid, and polyacrylic acid can also be used. These mixing ratios can be set as required.

  The undercoat layer may contain an electron accepting substance. Examples of the electron-accepting material include organic pigments such as perylene pigment, bisbenzimidazole perylene pigment, polycyclic quinone pigment, indigo pigment, and quinacridone pigment described in JP-A-47-30330, cyano group, nitro group, Examples thereof include electron-accepting substances such as bisazo pigments having electron-withdrawing substituents such as nitroso groups and halogen atoms, and organic pigments such as phthalocyanine pigments. The electron accepting substance may be mixed / dispersed with the metal oxide particles and included in the undercoat layer. Among these electron-accepting materials (pigments), perylene pigments, bisbenzimidazole perylene pigments and polycyclic quinone pigments are preferably used because they have higher electron-accepting properties. The effect can be expected more. The surface of these electron-accepting materials (pigments) may be surface-treated with the above-mentioned coupling agent or binder for the purpose of controlling dispersibility and charge acceptability.

  What mixed the said component is used for the coating liquid for undercoat layer formation. For example, a conventional method using a ball mill, a roll mill, a sand mill, an attritor, an ultrasonic wave, or the like is applied as a method for mixing / dispersing the metal oxide particles and the electron accepting substance. Mixing / dispersing is carried out in an organic solvent, as long as the organic solvent dissolves the resin and does not cause gelation or aggregation when the inorganic metal compound and the electron-accepting pigment are mixed / dispersed. Anything can be used. For example, methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran, methylene chloride, chloroform, chlorobenzene Ordinary organic solvents such as toluene can be used alone or in admixture of two or more.

  Here, when two or more undercoat layers have the same composition, they are highly compatible with each other, more improved in adhesion, and desirable results can be obtained from the viewpoint of securing a conduction path. The same composition means that the types of substances contained in the undercoat layer are the same. For example, the metal oxide particles having different particle diameters or different dispersion states have the same composition. Thereby, two or more undercoat layers are easy to be familiar with each other, delamination is suppressed, and cost reduction is realized.

  In this case, the properties of the coating liquid for forming the undercoat layer of each layer can be determined by the following definition of the light transmittance. That is, for example, a coating solution for forming an undercoat layer containing metal oxide particles, an electron accepting substance and a binder resin is applied on a glass plate so that the thickness after drying is 20 μm, and after drying, The film transmittance of the undercoat layer can be defined by measuring the light transmittance of the film at a wavelength of 950 nm using a spectrophotometer. In general, the smaller the secondary particle diameter, the higher the light transmittance. In general, the higher the light transmittance, the larger the volume resistivity, and the lower the light transmittance, the smaller the volume resistivity. It is preferable that the light transmittance of the undercoat layer farther is 20% or more and 40% or less, and the light transmittance of the undercoat layer closer to the conductive support is 70% or more and 80% or less. In other words, the secondary particle diameter of the metal oxide particles and the volume resistivity of the undercoat layer can be adjusted by measuring the light transmittance of the undercoat layer forming coating solution.

  In addition, in order to prevent light reflection of the conductive support, resin particles having a primary particle size of 1.0 μm or more can be dispersed in the undercoat layer. In this case, the resin particles can be mixed / dispersed after determining the light transmittance of the undercoat layer.

  In general, the total thickness of the undercoat layer is suitably from 0.1 μm to 40 μm. At this time, the film thickness of each of the two or more undercoat layers may be arbitrary, and the total film thickness of the undercoat layers may be in the above range. In addition, as the coating method used when the undercoat layer is provided, conventional methods such as a blade coating method, a Meyer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, and a curtain coating method are used. Can be used. The coated layer is dried to obtain an undercoat layer. Usually, the drying is performed at a temperature at which the solvent can be evaporated to form a film.

  Next, the charge generation layer will be described. The charge generation layer is made of, for example, a known charge generation material and a binder resin. The charge generating material is preferably a metal phthalocyanine pigment, particularly gallium phthalocyanine having a specific crystal described below, and good results for ghosts can be obtained. The chlorogallium phthalocyanine used in the present invention is produced by a known method, for example, as disclosed in JP-A-5-263007 and JP-A-5-279591.

The binder resin can be selected from a wide range of insulating resins, and can also be selected from organic photoconductive polymers such as poly-N-vinylcarbazole, polyvinylanthracene, polyvinylpyrene, and polysilane. Desirable binder resins include polyvinyl butyral resin, polyarylate resin (polycondensate of bisphenol A and phthalic acid, etc.), polycarbonate resin, polyester resin, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyamide resin, acrylic resin. Insulating resins such as polyacrylamide resin, polyvinyl pyridine resin, cellulose resin, urethane resin, epoxy resin, casein, polyvinyl alcohol resin, and polyvinyl pyrrolidone resin are not limited thereto. These binder resins can be used alone or in admixture of two or more. Here, “insulating” means that the volume resistivity is 10 ¹³ Ωcm or more.

  The blending ratio of the charge generation material and the binder resin (weight ratio) is preferably in the range of 10: 1 to 1:10. In addition, as a method for dispersing these, a usual method such as a ball mill dispersion method, an attritor dispersion method, a sand mill dispersion method, or the like can be used, but in this case, a condition that the crystal type does not change by dispersion is required. . Incidentally, it has been confirmed that the crystal form is not changed before dispersion in any of the dispersion methods implemented in the present invention. Further, at the time of dispersion, it is effective to make the particles have a particle size of 0.5 μm or less, desirably 0.3 μm or less, and more desirably 0.15 μm or less. Moreover, as a solvent used for these dispersions, methanol, ethanol, n-propanol, n-butanol, benzyl alcohol, methyl cellosolve, ethyl cellosolve, acetone, methyl ethyl ketone, cyclohexanone, methyl acetate, n-butyl acetate, dioxane, tetrahydrofuran Ordinary organic solvents such as methylene chloride, chloroform, chlorobenzene and toluene can be used alone or in admixture of two or more. The thickness of the charge generation layer used in the present invention is generally from 0.1 μm to 5 μm, preferably from 0.2 μm to 2.0 μm. In addition, as a coating method used when the charge generation layer is provided, a normal method such as a blade coating method, a Meyer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method is used. Can be used. Further, a pigment treated for the purpose of increasing the dispersion stability of the pigment, the light sensitivity, or stabilizing the electrical characteristics may be used.

  The film thickness of the charge generation layer is desirably from 0.1 μm to 5 μm, and more desirably from 0.2 μm to 2.0 μm.

  Next, the charge transport layer will be described. As the charge transport layer, a layer formed by a known technique can be used. These charge transport layers are formed containing a charge transport material and a binder resin, or are formed containing a polymer charge transport material.

  Examples of charge transport materials include quinone compounds such as p-benzoquinone, chloranil, bromanyl, anthraquinone, tetracyanoquinodimethane compounds, fluorenone compounds such as 2,4,7-trinitrofluorenone, xanthone compounds, benzophenone compounds Electron transporting compounds such as cyanovinyl compounds and ethylene compounds, triarylamine compounds, benzidine compounds, arylalkane compounds, aryl-substituted ethylene compounds, stilbene compounds, anthracene compounds, hydrazone compounds, etc. Examples thereof include pore-transporting compounds. These charge transport materials may be used alone or in combination of two or more, but are not limited thereto. In addition, these charge transport materials can be used alone or in combination of two or more, but those having the following structure are desirable from the viewpoint of mobility.

(In the formula, R ₁ represents a hydrogen atom or a methyl group. Further, n represents 1 or 2. Ar ₁ and Ar ₂ each independently represents a substituted or unsubstituted aryl group. Is a substituted amino group substituted with a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or an alkyl group having 1 to 3 carbon atoms Is shown.)

(Wherein R ₂ and R _{2 ′} may be the same or different and each represents a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, or an alkoxy group having 1 to 5 carbon atoms. R ₃ , R _{3 ′} , R ₄ and R _{4 ′} may be the same or different and are a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, or 1 or more carbon atoms. Represents an amino group substituted with 2 or less alkyl groups, a substituted or unsubstituted aryl group, or —C (R ₅ ) ═C (R ₆ ) (R ₇ ), wherein R ₅ , R ₆ , R ₇ are And may be the same or different and each represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group, and m and n are integers of 0 or more and 2 or less.)

(Wherein R ₈ is a hydrogen atom, an alkyl group having 1 to 5 carbon atoms, an alkoxy group having 1 to 5 carbon atoms, a substituted or unsubstituted aryl group, or —CH═CH—CH═C (Ar ) .Ar representing the _2, .R _9, R ₁₀ representing a substituted or unsubstituted aryl group may be the same or different, a hydrogen atom, a halogen atom, an alkyl group having 1 to 5 carbon atoms, 1 to 4 carbon atoms And represents an alkoxy group having 5 or less, an amino group substituted with an alkyl group having 1 to 2 carbon atoms, or a substituted or unsubstituted aryl group.

  The binder resin used for the charge transport layer is polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyvinyl chloride resin, polyvinylidene chloride resin, polystyrene resin, polyvinyl acetate resin, styrene-butadiene copolymer, vinylidene chloride-acrylonitrile. Copolymer, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, silicone resin, silicone-alkyd resin, phenol-formaldehyde resin, styrene-alkyd resin, poly-N-vinyl Polymer charge transport materials such as carbazole, polysilane, and polyester-based polymer charge transport materials disclosed in JP-A-8-176293 and JP-A-8-208820 can also be used. These binder resins can be used alone or in admixture of two or more. The blending ratio (weight ratio) between the charge transport material and the binder resin is preferably 10: 1 to 1: 5.

  In the charge transport layer, a polymer charge transport material can be used alone as a charge transport material. As the polymer charge transporting material, known materials having charge transporting properties such as poly-N-vinylcarbazole and polysilane can be used. In particular, polyester polymer charge transport materials disclosed in JP-A-8-176293 and JP-A-8-208820 have a high charge transport property and are particularly desirable. The polymer charge transport material alone can be used as the charge transport layer, but it may be formed by mixing with the binder resin.

  The charge transport layer may contain a fluorine resin. The content of the fluoric resin in the charge transport layer containing the fluoric resin is suitably from 0.1 wt% to 40 wt%, particularly preferably from 1 wt% to 30 wt%, based on the total amount of the charge transport layer. . If the content is less than 1 wt%, the modification effect due to the dispersion of the fluororesin particles is not sufficient. On the other hand, if the content exceeds 40 wt%, the light transmission property decreases and the residual potential increases due to repeated use. is there.

  Fluorine-based resins include tetrafluoroethylene resin, trifluoroethylene chloride resin, hexafluoropropylene resin, vinyl fluoride resin, vinylidene fluoride resin, difluorodifluoroethylene resin, and copolymers thereof. It is desirable to select one type or two or more types from the above, and in particular, tetrafluoroethylene resin and vinylidene fluoride resin are desirable.

  The primary particle size of the fluororesin is preferably 0.05 μm or more and 1 μm or less, and more preferably 0.1 μm or more and 0.5 μm or less. When the primary particle size is less than 0.05 μm, aggregation at the time of dispersion may easily proceed. If it exceeds 1 μm, image quality defects may easily occur.

  As a method of dispersing the fluororesin in the charge transport layer, there are a roll mill, a ball mill, a vibrating ball mill, an attritor, a sand mill, a high pressure homogenizer, an ultrasonic disperser, a colloid mill, a collision type medialess disperser, and a penetrating medialess disperser. Etc. can be used.

Examples of the dispersion of the coating liquid for forming the charge transport layer include a method of dispersing the fluorine-based resin particles in a solution of a binder resin, a charge transport material or the like dissolved in a solvent.
As a method of controlling the temperature of the coating liquid in the coating liquid manufacturing process to 0 ° C. or higher and 50 ° C. or lower, it is cooled with water, cooled with wind, cooled with a refrigerant, and the room temperature (for example, 25 ° C.) of the manufacturing process is adjusted. Warm with warm water, warm with hot air, warm with a heater, create a coating liquid manufacturing facility with a material that does not easily generate heat, create a coating liquid manufacturing facility with a material that easily dissipates heat, create a coating liquid manufacturing facility with a material that easily stores heat Etc. can be used. As a premixing method for the coating liquid, methods such as a stirrer, stirring with a stirring blade, a roll mill, a sand mill, an attritor, a ball mill, a high pressure homogenizer, and an ultrasonic disperser can be used. As a dispersion method, a sand mill, an attritor, a ball mill, a high-pressure homogenizer, an ultrasonic disperser, a roll mill, or the like can be used.

  It is also effective to add a small amount of a dispersion aid in order to improve the dispersion stability of the dispersion and to prevent aggregation during the formation of the coating film. Examples of the dispersion aid include fluorine-based surfactants, fluorine-based polymers, silicone-based polymers, and silicone oils.

  As a coating method, a usual method such as a blade coating method, a Mayer bar coating method, a spray coating method, a dip coating method, a bead coating method, an air knife coating method, or a curtain coating method can be used. Solvents used when providing the charge transport layer include aromatic hydrocarbons such as benzene, toluene, xylene and chlorobenzene, ketones such as acetone and 2-butanone, and halogenated fats such as methylene chloride, chloroform and ethylene chloride. Ordinary organic solvents such as aromatic hydrocarbons, cyclic ethers such as tetrahydrofuran and ethyl ether, or straight-chain ethers can be used alone or in admixture of two or more.

  The thickness of the charge transport layer is desirably 5 μm or more and 50 μm or less, and more desirably 10 μm or more and 30 μm or less.

  Next, the protective layer will be described. The protective layer can contain a known charge transport material and a resin. Examples of the protective layer include those obtained by dispersing a charge transfer agent and metal oxide particles in a thermoplastic resin, and those containing a resin having a crosslinked structure and a reactive charge transfer agent. From the viewpoint of strength, electrical characteristics, image quality maintenance, etc., those having a crosslinked structure are desirable. Various materials can be used to form a cross-linked structure, but phenolic resins, epoxy resins, urethane resins, siloxane resins, etc. are desirable due to their characteristics, and are composed of siloxane resins and phenolic resins. Is more desirable.

From the viewpoint of obtaining an image free from image quality defects over a longer period, the protective layer is at least one selected from a phenol derivative having a methylol group, a hydroxyl group, a carboxyl group, an alkoxysilyl group, an epoxy group, a thiol group, and an amino group. It is desirable to include a charge transport material having a seed. In addition, these charge transport materials may be incorporated into a crosslinked structure as a structural unit having charge transport ability by reacting with a resin or reacting with a compound constituting the resin.
Examples of the phenol derivative having a methylol group include monomers of monomethylolphenols, dimethylolphenols or trimethylolphenols, mixtures thereof, oligomers thereof, or mixtures of these monomers and oligomers. This phenol derivative having a methylol group is a substituted phenol containing one hydroxyl group such as resorcin, bisphenol, etc., phenol, cresol, xylenol, paraalkylphenol, paraphenylphenol, etc., and two hydroxyl groups such as catechol, resorcinol, hydroquinone, etc. It is obtained by reacting phenolic compounds such as bisphenols such as bisphenol A and bisphenol Z, biphenols, etc., and compounds having a phenol structure with formaldehyde, paraformaldehyde, etc. in the presence of an acid catalyst or alkaline catalyst. What is marketed as resin can also be used. In the present specification, a relatively large molecule in which the number of repeating structural units of the molecule is 2 or more and 20 or less is called an oligomer, and a molecule smaller than that is called a monomer.

The thickness of the protective layer is preferably from 0.5 μm to 15 μm, more preferably from 1 μm to 10 μm, and even more preferably from 1 μm to 7 μm.

  Next, a single layer type photosensitive layer will be described. The single-layer type photosensitive layer includes, for example, a charge generation material and a binder resin, and includes a charge transport material as necessary. The content of the charge generating material in the single-layer type photosensitive layer is about 10% by weight to 85% by weight, desirably 20% by weight to 50% by weight. In addition, the content of the charge transport material is desirably 5% by mass or more and 50% by mass or less. The film thickness of the single-layer type photosensitive layer is preferably about 5 μm to 50 μm, and more preferably 10 μm to 40 μm.

  Additives such as antioxidants, light stabilizers, heat stabilizers, etc. are added to the photosensitive layer for the purpose of preventing deterioration of the photoreceptor due to ozone, oxidizing gas, or light and heat generated in the copying machine. can do. For example, examples of the antioxidant include hindered phenol, hindered amine, paraphenylenediamine, arylalkane, hydroquinone, spirochroman, spiroidanone and derivatives thereof, organic sulfur compounds, and organic phosphorus compounds. Examples of the light stabilizer include derivatives such as benzophenone, benzotriazole, dithiocarbamate, and tetramethylpiperidine.

For the purpose of improving sensitivity, reducing residual potential, reducing fatigue during repeated use, and the like, the photosensitive layer can contain at least one electron accepting substance. Examples of the electron acceptor include succinic anhydride, maleic anhydride, dibromomaleic anhydride, phthalic anhydride, tetrabromophthalic anhydride, tetracyanoethylene, tetracyanoquinodimethane, o-dinitrobenzene, m-dinitrobenzene, Examples include chloranil, dinitroanthraquinone, trinitrofluorenone, picric acid, o-nitrobenzoic acid, p-nitrobenzoic acid, phthalic acid and the like, and compounds represented by general formula (I). Among these, benzene derivatives having electron-withdrawing substituents such as fluorenone-based, quinone-based, Cl, CN, and NO ₂ are particularly desirable.

(Image forming device)
The image forming apparatus according to the embodiment includes the electrophotographic photosensitive member according to the embodiment,
Charging means for charging the electrophotographic photosensitive member; electrostatic latent image forming means for exposing the electrophotographic photosensitive member to form an electrostatic latent image; and developing means for developing the electrostatic latent image with toner; Transfer means for transferring the toner image to a transfer medium.

  An image forming apparatus according to an embodiment will be described with reference to the drawings. FIG. 5 is a schematic configuration diagram illustrating the image forming apparatus according to the embodiment.

  The image forming apparatus 100 shown in FIG. 5 includes an electrophotographic photosensitive member 7 provided to rotate. Around the electrophotographic photoreceptor 7, along the movement direction of the outer peripheral surface of the electrophotographic photoreceptor 7, a charging device (charging means) 8, an exposure device 10, a developing device 11, a transfer device 12, a cleaning device 13, A static eliminator (erase device) 14 is arranged in this order.

The charging device 8 is a corona charging type charging device and charges the electrophotographic photoreceptor 7. Examples of the charging device 8 include a corotron charger and a scorotron charger. The charging device 8 is connected to a power source 9.
The exposure device 10 exposes the charged electrophotographic photosensitive member 7 to form an electrostatic latent image on the electrophotographic photosensitive member 7.

The developing device 11 develops the electrostatic latent image with a developer to form a toner image. The developer preferably contains toner particles obtained by a polymerization method, for example, having a volume average particle diameter of 3 μm or more and 9 μm or less.
The transfer device 12 transfers the toner image developed on the electrophotographic photoreceptor 7 to a transfer medium.

The cleaning device 13 removes toner remaining on the electrophotographic photosensitive member 7 after transfer. The cleaning device 13 preferably has a blade member that contacts the electrophotographic photoreceptor 7 at a linear pressure of 10 g / cm to 150 g / cm.
The static eliminator (erase device) 14 erases the remaining charges on the electrophotographic photosensitive member 7.
Further, the image forming apparatus 100 includes a fixing device 15 that fixes the toner image on the transfer medium after the transfer process.

FIG. 6 is a schematic configuration diagram illustrating an image forming apparatus according to another embodiment.
The image forming apparatus 110 shown in FIG. 6 has the same configuration as the image forming apparatus 100 shown in FIG. 5 except that the image forming apparatus 110 includes a charging device 8 that charges the electrophotographic photoreceptor 7 by a contact method. In particular, in the image forming apparatus 110 that employs a contact-type charging device (charging means) in which an AC voltage is superimposed on a DC voltage, the electrophotographic photoreceptor 7 can be desirably used because it has excellent leakage resistance. In this case, the static eliminator 14 may not be provided.

In the contact charging method, charging members such as a roller shape, a blade shape, a belt shape, a brush shape, and a magnetic brush shape are applicable. In particular, the roller-like or blade-like charging member may be arranged in a contact state or a non-contact state having a certain amount of voids (for example, 100 μm or less) with respect to the electrophotographic photoreceptor 7.
A roller-shaped charging member, a blade-shaped charging member, and a belt-shaped charging member are composed of a material adjusted to an electrical resistance (10 ³ Ω to 10 ⁸ Ω) effective as a charging member, and are a single layer. Or you may comprise from several layers.

  FIG. 7 is a schematic configuration diagram illustrating an image forming apparatus according to another embodiment. An image forming apparatus 200 shown in FIG. 7 is an image forming apparatus of a tandem type intermediate transfer system, and includes four electrophotographic photosensitive members 201a to 201d (for example, 201a is yellow, 201b is magenta, and 201c is cyan) in a housing 220. , 201d can form images of black color), and are arranged in parallel with each other along the intermediate transfer belt 209.

  Conventionally, as a method of transferring an image onto a transfer paper such as paper, there is a transfer drum method in which a transfer paper such as paper is wound around a transfer drum and a visible image on a photoconductor is transferred to the transfer paper for each color. Are known. In this case, compared to the tandem intermediate transfer method, the transfer of the visible image from the photosensitive member to the intermediate transfer member (intermediate transfer means) required the intermediate transfer member to rotate a plurality of times. This method has the advantage that the transfer speed can be improved by transferring the intermediate transfer belt 209 once, and the transfer speed can be improved, and the transfer medium can be selected as in the transfer drum method.

Here, the electrophotographic photoreceptors 201 a to 201 d mounted on the image forming apparatus 200 are the same as the electrophotographic photoreceptor 7.
Each of the electrophotographic photoreceptors 201a to 201d can be rotated in a predetermined direction (counterclockwise on the paper surface), and the charging rolls 202a to 202d, the developing devices 204a to 204d, and the primary transfer roll 210a along the rotation direction. Through 210d and cleaning devices 215a through 215d are arranged. Each of the developing devices 204a to 204d can supply toners of four colors, yellow, magenta, cyan, and black, which are accommodated in the toner cartridges 205a to 205d. Further, the primary transfer rolls 210a to 210d are in contact with the electrophotographic photoreceptors 201a to 201d via the intermediate transfer belt 209, respectively.

  Further, a laser light source 203 is disposed at a predetermined position in the housing 220. Laser light emitted from the laser light source 203 can be applied to the surfaces of the electrophotographic photoreceptors 201a to 201d after charging. Accordingly, charging, exposure, development, primary transfer, and cleaning are sequentially performed in the rotation process of the electrophotographic photoreceptors 201a to 201d, and the toner images of the respective colors are transferred onto the intermediate transfer belt 209 in an overlapping manner.

  The intermediate transfer belt 209 is supported with a predetermined tension by a drive roll 206, a backup roll 208, and a tension roll 207, and can rotate without causing deflection due to the rotation of these rolls. Further, the secondary transfer roll 213 is disposed so as to come into contact with the backup roll 208 via the intermediate transfer belt 209. The intermediate transfer belt 209 that has passed between the backup roll 208 and the secondary transfer roll 213 is cleaned by, for example, a cleaning blade 216 disposed near the drive roll 206 and then repeatedly used for the next image forming process. Is done.

  Further, a medium receiver 211 is provided at a predetermined position in the housing 220, and a transfer medium 230 such as paper in the medium receiver 211 is moved between the intermediate transfer belt 209 and the secondary transfer roll 213 by the transfer roll 212. Then, the paper is sequentially transferred between the two fixing rollers 214 that are in contact with each other, and then discharged to the outside of the housing 220.

  In the above description, the case where the intermediate transfer belt 209 is used as the intermediate transfer member (intermediate transfer unit) has been described. However, the intermediate transfer member is belt-like (for example, an endless belt-like belt) like the intermediate transfer belt 209. Or a drum shape. When a belt-shaped configuration such as the intermediate transfer belt 209 is adopted as the intermediate transfer member, generally the film thickness of the belt is preferably in the range of 50 μm to 500 μm, and more preferably in the range of 60 μm to 150 μm. The film thickness of the belt can be selected according to the hardness of the material. Further, when adopting a drum-shaped configuration as the intermediate transfer member, it is desirable to use a cylindrical substrate formed of aluminum, stainless steel (SUS), copper or the like as the substrate. If necessary, an elastic layer can be coated on the cylindrical substrate, and a surface layer can be formed on the elastic layer.

  The medium to be transferred is not particularly limited as long as it is a medium for transferring a toner image formed in the shape of an electrophotographic photosensitive member. For example, when transferring directly from an electrophotographic photosensitive member to paper or the like, paper or the like is a transfer medium, and when an intermediate transfer member is used, the intermediate transfer member is a transfer medium.

(Process cartridge)
The process cartridge according to the embodiment includes the electrophotographic photosensitive member according to the above-described embodiment, a charging unit that charges the electrophotographic photosensitive member, and an electrostatic latent image that forms an electrostatic latent image by exposing the electrophotographic photosensitive member. A developing unit that develops the electrostatic latent image with toner, and is detachable from the main body of the image forming apparatus.

  A process cartridge according to an embodiment will be described with reference to the drawings. FIG. 8 is a schematic configuration diagram illustrating a process cartridge according to the embodiment.

  A process cartridge 300 shown in FIG. 8 is integrated into a housing 301 by combining a charging device (charging means) 308, a developing device 311, a cleaning device 313, and a static eliminator 314 together with an electrophotographic photosensitive member 307 using a mounting rail 303. It has become. The process cartridge 300 is not provided with an exposure device, but an opening 305 for exposure is formed in the housing 301.

  The process cartridge 300 is detachable from an image forming apparatus main body including a transfer device 312, a fixing device 315, and other components (not shown), and constitutes an image forming apparatus together with the image forming apparatus main body. To do.

Hereinafter, the present invention will be described more specifically with reference to examples. However, these examples do not limit the present invention.

[Example A1]
(Preparation of electrophotographic photoreceptor)
As metal oxide particles, 100 parts by weight of zinc oxide (average particle size: 70 nm: prototype product: specific surface area value: 15 m ² / g) is stirred and mixed with 500 parts by weight of toluene, and a silane coupling agent (KBM603: Shin-Etsu Chemical Co., Ltd.) 1.25 parts by weight were added and stirred for 2 hours. Thereafter, toluene was distilled off under reduced pressure and baked at 120 ° C. for 3 hours to obtain a silane coupling agent surface-treated zinc oxide pigment.

  60 parts by weight of surface-treated zinc oxide, 0.3 parts by weight of alizarin (manufactured by Sigma Aldrich Japan), 13.5 parts by weight of blocked isocyanate Sumijour 3175 (manufactured by Sumitomo Bayern Urethane Co., Ltd.) and butyral resin BM-1 (Manufactured by Sekisui Chemical Co., Ltd.) 38 parts by weight of a solution obtained by dissolving 15 parts by weight of 85 parts by weight of methyl ethyl ketone and 25 parts by weight of methyl ethyl ketone were mixed and dispersed in a sand mill using 1 mmφ glass beads. The dispersion was sampled, and the obtained sampling solution was applied onto a glass plate so that the thickness after drying was 20 μm. After drying, the light transmittance of the film at a wavelength of 950 nm was measured using a spectrophotometer. It was measured. When the light transmittance at this time reached 80%, the dispersion was terminated, and an undercoat layer dispersion A1-1 was obtained. As a result of observing the cross section of this light transmittance measuring sample with a transmission electron microscope, the secondary particle diameter was 100 nm.

  Here, for the light transmittance by the photometer, a device name “Spectrophotometer (U-2000)” manufactured by Hitachi, Ltd. was used as a spectrophotometer.

  Next, using the dispersion prepared in the same manner as the undercoat layer dispersion A1-1, the dispersion was stopped when the light transmittance reached 25%, and the undercoat layer dispersion A2-1 was used. It was. The secondary particle size at this time was 180 nm as measured in the same manner as for the undercoat layer dispersion A1-1.

  Dioctyltin dilaurate: 0.005 parts by weight and silicone resin particle Tospearl 145 (manufactured by GE Toshiba Silicone): 4.0 parts by weight are added as catalysts to each of the obtained dispersions, and dispersion A1 for coating the undercoat layer -1, A2-1 was obtained.

  This coating solution is applied by dip coating method onto an aluminum substrate having a diameter of 30 mm, a length of 404 mm, and a wall thickness of 1 mm, in this order, undercoating layer coating dispersions A1-1 and A2-1, and 195 ° C. for 27 minutes. The undercoat layer 1 with the undercoat layer coating dispersion A1-1 was 9.5 μm (constant thickness), and the undercoat layer 2 with the undercoat layer coating dispersion A2-1 was 9.5 μm. (Thickness is constant) and two undercoat layers having a total thickness of 19 μm were obtained.

  Next, a photosensitive layer was formed on the undercoat layer as follows. First, a mixture comprising 15 parts of chlorogallium phthalocyanine as a charge generating substance, 10 parts by weight of vinyl chloride / vinyl acetate copolymer resin (VMCH, manufactured by Union Carbide) as a binder resin, and 200 parts by weight of n-butyl acetate. 1 mmφ glass beads were used for dispersion for 4 hours in a sand mill. To the obtained dispersion, 175 parts by weight of n-butyl acetate and 180 parts by weight of methyl ethyl ketone were added and stirred to obtain a coating solution for a charge generation layer. This charge generation layer coating solution was dip-coated on the undercoat layer and dried at room temperature to form a charge generation layer having a thickness of 0.2 μm.

  Furthermore, 4 parts of N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1 ′] biphenyl-4,4′-diamine and 6 weight of bisphenol Z polycarbonate resin (molecular weight 40,000) A coating solution prepared by adding 80 parts by weight of tetrahydrofuran was dissolved on the charge generation layer and dried at 115 ° C. for 40 minutes to form a charge transport layer having a thickness of 25 μm. In this way, a photosensitive layer was formed to obtain an electrophotographic photoreceptor.

(Evaluation)
The obtained electrophotographic photoreceptor was evaluated as follows.

-Ghost evaluation-
The electrophotographic photosensitive member produced as described above was mounted on DocuCenter Color a450 manufactured by Fuji Xerox Co., Ltd., and continuous printing was performed. The external environment during printing was 22 ° C. and 50% RH. The ghost was visually evaluated for the obtained first, tenth, 100th, 1000th, and 10000th images. The numbers in the table are as follows.
・ Ghost grade 0: No ghost is generated.
1: Generation of ghost is observed at a level that does not matter in practice.
2: Occurrence of ghost at a level of concern in some cases.
3: In some cases, ghosting is observed at a problematic level.
4: Generation of ghost is observed at a level that is problematic in practice.
In addition, this visual evaluation is based on the test of 20 subjects using the collected images, and specifically, the above “level that is substantially unattractive” is a response that a ghost is seen. It shows the state when it was less than%. In addition, the “level to be worried in some cases” specifically indicates a state where the answer is 10% or less. The “level that causes a problem in some cases” specifically indicates a state where the answer is 15% or more. Furthermore, “substantially becomes a problem” specifically indicates a state where the answer is 20% or more. In this evaluation, grade 3 or higher was judged as NG (NO GOOD: defective).

-Residual potential measurement-
In the electrophotographic photosensitive member and the image forming apparatus used for the ghost evaluation, after obtaining the 10,000th image, the electrophotographic photosensitive member and the image forming apparatus are modified so that a potential measuring probe (Treck 344 manufactured by Trek) can be attached to the developing device position of the image forming apparatus. Was measured. The parameters of the image forming apparatus were changed so that the potential measurement conditions were as follows.
Charging potential: -700V
Potential after exposure: -200V
Photoreceptor process speed: 165 mm / sec.

[Example A2]
In Example A1, an electrophotographic photosensitive member was produced in the same manner as in Example A1, except that titanium oxide was used as the metal oxide particle of the undercoat layer dispersion A2-1. At this time, the light transmittance of the undercoat layer dispersion A2-2 was 25%, and the secondary particle size was 200 nm. The electrophotographic photoreceptor was evaluated by the same method as in Example A1-1.

[Example A3]
In Example A1, undercoat layer dispersions A1-2 and A2-3 were prepared in the same manner as Example A1-1, except that alizarin was not added to both of the undercoat layer dispersions A1-1 and A2-1. . The light transmittance and the secondary particle size at this time were 85% and 120 nm for the undercoat layer dispersion A1-2, and 30% and 200 nm for the undercoat layer dispersion A2-3. The electrophotographic photoreceptor was evaluated by the same method as in Example A1.

[Example A4]
An electrophotographic photosensitive member was produced in the same manner as in Example A3 except that titanium oxide was used as the metal oxide particle in the undercoat layer dispersion A2-3 in Example A3. At this time, the light transmittance of the undercoat layer dispersion A2-4 was 25%, and the secondary particle size was 200 nm. The electrophotographic photoreceptor was evaluated by the same method as in Example A1. The results are shown in Table 2.

[Example A5]
The coating liquid A1-1 for coating the undercoat layer of Example A1 was applied on an aluminum substrate having a diameter of 30 mm, a length of 404 mm, and a thickness of 1 mm by a dip coating method, followed by drying and curing at 195 ° C. for 27 minutes to obtain a thickness. An undercoat layer 1 having a thickness of 10 μm was obtained. Thereafter, the undercoat layer dispersion A2-1 of Example A1 was applied onto the undercoat layer 1 to obtain an undercoat layer having a thickness of 10 μm. Thereafter, a charge generation layer and a charge transport layer were formed in the same manner as in Example A1, and evaluation was performed in the same manner as in Example A1.

[Example A6]
In Example A1, a dispersion prepared in the same manner as the undercoat layer dispersion A1-1 was used, and the dispersion was stopped when the light transmittance reached 50%. -3. The secondary particle diameter of this dispersion A3-1 was 130 nm. The undercoat layer dispersions A1-1 and A2-1 in Example A1 and the undercoat layer dispersion A1-3 in Example A6 are dip-coated in the order of A1-1, A1-3, and A2-1. Is applied onto an aluminum substrate having a diameter of 30 mm, a length of 404 mm, and a wall thickness of 1 mm, dried and cured at 195 ° C. for 27 minutes, and the undercoat layer 1 with the undercoat layer coating dispersion A1-1 is obtained. 5 μm (the thickness is constant), the undercoat layer 2 by the undercoat layer coating dispersion A2-1 is 6.5 μm (the thickness is constant), and the undercoat layer 3 by the undercoat layer coating dispersion A1-3 is 6 μm. (Thickness is constant) and three undercoat layers with a total thickness of 19 μm were obtained. Thereafter, a charge generation layer and a charge transport layer were formed in the same manner as in Example A1, and evaluation was performed in the same manner as in Example A1.

[Example A7]
In Example A1, the undercoat layer dispersions A1-1 and A2-1 were applied on the aluminum substrate in the reverse order. Thereafter, a charge generation layer and a charge transport layer were formed in the same manner as in Example A1, and evaluation was performed in the same manner as in Example A1.

[Example A8]
In Example A1, a dispersion prepared in the same manner as the undercoat layer dispersion A1-1 was used, and the dispersion was stopped when the light transmittance reached 60%. -4. The secondary particle size at this time was 110 nm as measured in the same manner as for the undercoat layer dispersion A1-1. These undercoat layer dispersions A1-1 and A1-4 were applied on the aluminum substrate in this order in the same manner as in Example A1. Thereafter, a charge generation layer and a charge transport layer were formed in the same manner as in Example A1, and evaluation was performed in the same manner as in Example A1.

[Comparative Example A1]
In Example A1, an electrophotographic photosensitive member was produced in the same manner as in Example A1, except that the undercoat layer dispersion A2-1 did not contain metal oxide particles. In this case, the light transmittance of the undercoat layer dispersion was 90%, and the secondary particle size was 120 nm. The electrophotographic photoreceptor was evaluated by the same method as in Example A1.

[Comparative Example A2]
An electrophotographic photoreceptor was prepared in the same manner as in Example A1, except that the undercoat layer was formed using only the undercoat layer dispersion A1-1 prepared in Example A1. The electrophotographic photoreceptor was evaluated by the same method as in Example A1.

[Comparative Example A3]
An electrophotographic photosensitive member was produced in the same manner as in Example A1, except that the undercoat layer was formed using only the undercoat layer dispersion A2-1 produced in Example A1. The electrophotographic photoreceptor was evaluated by the same method as in Example A1.

  Tables 1 and 2 show the outline of each example and a list of evaluation results.

[Example B1]
-Production of electrophotographic photoreceptor-
As metal oxide particles, 100 parts by weight of zinc oxide (average particle size: 70 nm: prototype product: specific surface area value: 15 m ² / g) is stirred and mixed with 500 parts by weight of toluene, and a silane coupling agent (KBM603: Shin-Etsu Chemical Co., Ltd.) 1.25 parts by weight were added and stirred for 2 hours. Thereafter, toluene was distilled off under reduced pressure and baked at 120 ° C. for 3 hours to obtain a silane coupling agent surface-treated zinc oxide pigment.

60 parts by weight of surface-treated zinc oxide, 0.3 parts by weight of alizarin (manufactured by Sigma Aldrich Japan), 13.5 parts by weight of blocked isocyanate Sumijour 3175 (manufactured by Sumitomo Bayern Urethane Co., Ltd.) and butyral resin BM-1 (Manufactured by Sekisui Chemical Co., Ltd.) 38 parts by weight of a solution obtained by dissolving 15 parts by weight of 85 parts by weight of methyl ethyl ketone and 25 parts by weight of methyl ethyl ketone were mixed and dispersed in a sand mill using 1 mmφ glass beads. The dispersion is appropriately sampled, and the obtained sampling solution is applied onto a glass plate so that the thickness after drying is 20 μm. After drying, the light transmittance of the film at a wavelength of 950 nm is measured using a spectrophotometer. Was measured. When the light transmittance at this time reached 80%, the dispersion was terminated to obtain an undercoat layer dispersion B1-1. The volume resistivity of this light transmittance measurement sample was measured and found to be 1.0 × 10 ^12.5 (Ω · cm).

Next, using a dispersion prepared in the same manner as the undercoat layer dispersion B1-1, the dispersion was stopped when the light transmittance reached 25%, and the undercoat layer dispersion B2-1 was used. It was. The volume resistivity of the sample for measuring light transmittance was measured and found to be 1.0 × 10 ¹⁰ (Ω · cm).

  Dioctyltin dilaurate: 0.005 parts by weight and silicone resin particle Tospearl 145 (manufactured by GE Toshiba Silicone): 4.0 parts by weight are added as catalysts to each of the obtained dispersions, and dispersion B1 for coating the undercoat layer -1, B2-1 was obtained.

  This coating solution was applied in the order of undercoat layer coating dispersions B1-1 and B2-1 onto an aluminum substrate having a diameter of 30 mm, a length of 404 mm, and a thickness of 1 mm by a dip coating method. At this time, the dispersion B1-1 for coating the undercoat layer was maximized at the center, and the dispersion B2-1 for coating the undercoat layer was maximized at the end. Thereafter, drying and curing is performed at 195 ° C. for 27 minutes, and the undercoat layer coating dispersion B1-1 is applied to the undercoat layer 1 with an effective photosensitive region center film thickness of 18 μm and an end film thickness of 4 μm. A subbing layer having a total film thickness of 22 μm (constant) was obtained with a film thickness of 4 μm at the center of the effective photosensitive region of the subbing layer 2 and a film thickness of 18 μm at the end. The difference in the combined volume resistivity between the central portion and the end portion of the effective photosensitive region in this state is represented by Δ (Ω · cm) and is shown in Table 4.

  Next, a photosensitive layer was formed on the undercoat layer as follows. A mixture of 15 parts by weight of chlorogallium phthalocyanine as a charge generating substance, 10 parts by weight of vinyl chloride / vinyl acetate copolymer resin (VMCH, manufactured by Union Carbide) as a binder resin, and 200 parts of n-butyl acetate was added to 1 mmφ Were dispersed in a sand mill for 4 hours. To the obtained dispersion, 175 parts by weight of n-butyl acetate and 180 parts by weight of methyl ethyl ketone were added and stirred to obtain a coating solution for a charge generation layer. This charge generation layer coating solution was dip coated on the undercoat layer and dried at room temperature (25 ° C.) to form a charge generation layer having a thickness of 0.2 μm.

  Furthermore, 4 parts of N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1 ′] biphenyl-4,4′-diamine and 6 weight of bisphenol Z polycarbonate resin (molecular weight 40,000) A coating solution prepared by adding 80 parts by weight of tetrahydrofuran was dissolved on the charge generation layer and dried at 115 ° C. for 40 minutes to form a charge transport layer having a thickness of 25 μm. In this way, a photosensitive layer was formed to obtain an electrophotographic photoreceptor.

(Evaluation)
The following evaluation was performed about the obtained photoreceptor.

-Concentration evaluation-
The electrophotographic photosensitive member produced as described above was mounted in a magenta color of DocuCenter Color a450 manufactured by Fuji Xerox Co., Ltd., and an entire halftone of 30% density was printed in A3 size. The external environment during printing was 22 ° C. and 50% RH. With respect to the obtained image, the image center density and edge density in the axial direction of the electrophotographic photosensitive member were measured. For the concentration measurement, trade name X-Rite 404 manufactured by X-Rite was used. The difference between the obtained central portion concentration and end portion concentration is represented by ΔD, and the evaluation results are shown in Table 4. The smaller ΔD, the higher the in-plane density uniformity, and ΔD> 0.2 was defined as NG (NO GOOD). At the same time, the presence or absence of image quality failure was confirmed.

  The presence or absence of image quality failure was judged visually. Specifically, it is a background dot to a color point or a non-printing area, and it is determined as NG when the occurrence is recognized.

-Surface potential measurement-
In the electrophotographic photosensitive member and the image forming apparatus used in the density evaluation, after obtaining an image, the electrophotographic photosensitive member and the image forming apparatus are modified so that a potential measuring probe (Treck 344 manufactured by Treck) can be attached to the developing device position of the image forming apparatus. The surface potential of the part and the end part was measured. The obtained difference in surface potential was represented by ΔV, and the evaluation results are shown in Table 4. The parameters of the image forming apparatus were changed so that the potential measurement conditions were as follows.
Potential after charging: -700V
Exposure energy: 4.5 mJ / m ²
Photoreceptor process speed: 165 mm / sec.

-Ghost evaluation-
The electrophotographic photosensitive member produced as described above was mounted on DocuCenter Color a450 manufactured by Fuji Xerox Co., Ltd., and continuous printing was performed. The external environment during printing was 22 ° C. and 50% RH. The ghost was visually evaluated for the obtained first, tenth, 100th, 1000th, and 10000th images. The evaluation results are shown in Table 2. The numbers in the table are as follows.
・ Ghost grade 0: No ghost is generated.
1: Generation of ghost is observed at a level that does not matter in practice.
2: Occurrence of ghost at a level of concern in some cases.
3: In some cases, ghosting is observed at a problematic level.
4: Generation of ghost is observed at a level that is problematic in practice.
In addition, this visual evaluation is based on the test of 20 subjects using the collected images, and specifically, the above “level that is substantially unattractive” is a response that a ghost is seen. It shows the state when it was less than%. In addition, the “level to be worried in some cases” specifically indicates a state where the answer is 10% or less. The “level that causes a problem in some cases” specifically indicates a state where the answer is 15% or more. Furthermore, “substantially becomes a problem” specifically indicates a state where the answer is 20% or more. In this evaluation, grade 3 or higher was judged as NG (NO GOOD: defective).

-Residual potential measurement-
In the electrophotographic photosensitive member and the image forming apparatus used for the ghost evaluation, after obtaining the 10,000th image, the electrophotographic photosensitive member and the image forming apparatus are modified so that a potential measuring probe (Treck 344 manufactured by Trek) can be attached to the developing device position of the image forming apparatus. Was measured. The evaluation results are shown in Table 2. The parameters of the image forming apparatus were changed so that the potential measurement conditions were as follows.
Charging potential: -700V
Potential after exposure: -200V
Photoreceptor process speed: 165 mm / sec.

[Example B2]
An electrophotographic photoreceptor was prepared in the same manner as in Example B1, except that in Example B1, the metal oxide particles of the undercoat layer dispersion B2-1 were changed to titanium oxide to make the undercoat layer dispersion B2-2. The electrophotographic photoreceptor was evaluated by the same method as in Example B1.

[Example B3]
Undercoat layer dispersions B1-2 and B2-3 were prepared in the same manner as in Example B1, except that alizarin was not added to the undercoat layer dispersions B1-1 and B2-1 in Example B1. did. The electrophotographic photoreceptor was evaluated by the same method as in Example B1.

[Example B4]
An electrophotographic photosensitive member was produced in the same manner as in Example B3 except that titanium oxide was used as the metal oxide particle in the undercoat layer dispersion B2-3 in Example B3. The electrophotographic photoreceptor was evaluated by the same method as in Example B1.

[Example B5]
The coating liquid B1-1 for coating the undercoat layer of Example B1 was applied on an aluminum substrate having a diameter of 30 mm, a length of 404 mm, and a thickness of 1 mm by a dip coating method, followed by drying and curing at 195 ° C. for 27 minutes. An undercoat layer 1 having a thickness of 10 μm was obtained. Thereafter, the undercoat layer dispersion B2-1 of Example B1 was applied on the undercoat layer 1 to obtain an undercoat layer having a total thickness of 15 μm (constant). At that time, the film thickness of the central portion of the effective photosensitive region of the undercoat layer 1 is 10 μm and the film thickness of the end portion is 5 μm, and the film thickness of the central portion of the effective photosensitive region of the undercoat layer 2 is 5 μm. Thereafter, a charge generation layer and a charge transport layer were formed in the same manner as in Example B1, and evaluation was performed in the same manner as in Example B1.

[Example B6]
In Example B1, a dispersion prepared in the same manner as the undercoat layer dispersion B1-1 was used, and the dispersion was stopped when the light transmittance reached 50%. -3. Then, using the produced undercoat layer dispersion 3 together with the undercoat layer dispersions B1-1 and B2-1 of Example B1, aluminum having a diameter of 30 mm, a length of 404 mm, and a wall thickness of 1 mm was obtained by a dip coating method. The undercoat layer coating dispersions B1-1, B1-3, and B2-1 were applied in this order on the substrate. At this time, the dispersion B1-1 for coating the undercoat layer is maximized at the center, and the dispersion B2-2 for coating the undercoat layer is maximized at the end. The coating layer dispersion 3 was designed to have an intermediate film thickness between the undercoating layers 1 and 2 at both the center and the end. Thereafter, drying and curing is performed at 195 ° C. for 27 minutes, and the undercoat layer coating dispersion B1-1 is applied to the undercoat layer 1 with an effective photosensitive region center film thickness of 18 μm and an end film thickness of 4 μm. The film thickness of the central portion of the effective photosensitive region of the undercoat layer 2 with the liquid B2-1 is 4 μm, the film thickness of the end portion is 22 μm, the film thickness of the central portion of the effective photosensitive region of the undercoat layer 3 with the dispersion B1-3 for coating the undercoat layer An undercoat layer having an end film thickness of 5 μm and a total film thickness of 31 μm (constant) was obtained. Thereafter, a charge generation layer and a charge transport layer were formed in the same manner as in Example B1, and evaluation was performed in the same manner as in Example B1.

[Example B7]
In Example B1, the effective photosensitive region central film thickness 4 μm and end film thickness 18 μm of the undercoat layer 1 with the undercoat layer coating dispersion B1-1 An undercoat layer having a total film thickness of 22 μm (constant) was obtained with a film thickness of 18 μm at the center of the effective photosensitive region of the pull layer 2 and 4 μm at the end film thickness. Thereafter, a charge generation layer and a charge transport layer were formed in the same manner as in Example B1, and evaluation was performed in the same manner as in Example B1.

[Example B8]
In Example B1, an undercoat layer was obtained in the same manner as in Example B1, except that the undercoat layer coating dispersions B1-1 and B2-1 were applied on the aluminum substrate in reverse order. Thereafter, a charge generation layer and a charge transport layer were formed in the same manner as in Example B1, and evaluation was performed in the same manner as in Example B1.

[Comparative Example B1]
In Example B6, an electrophotographic photosensitive member was produced in the same manner as in Example B6 except that the undercoat layer dispersions B2-2 and B1-3 did not contain metal oxide particles. The electrophotographic photoreceptor was evaluated by the same method as in Example B1.

[Comparative Example B2]
An electrophotographic photoreceptor was prepared in the same manner as in Example B1 except that the undercoat layer was formed using only the undercoat layer dispersion B1-1 prepared in Example B1 and the film thickness was kept constant at 22 μm. . The electrophotographic photoreceptor was evaluated by the same method as in Example B1.

[Comparative Example B3]
An electrophotographic photosensitive member was produced in the same manner as in Example B1 except that the undercoat layer was formed using only the undercoat layer dispersion B1-3 produced in Example B6 and the film thickness was kept constant at 22 μm. . The electrophotographic photoreceptor was evaluated by the same method as in Example B1.

[Comparative Example B4]
In the electrophotographic photosensitive member produced in Comparative Example B2, the film thickness of the charge generation layer in the effective photosensitive region was maximized at the end (the film thickness of the central portion of the effective photosensitive region of the charge generation layer was 0.1 μm, the end For the part thickness of 0.2 μm, an electrophotographic photosensitive member was produced in the same manner as in Comparative Example B2.

  Tables 3 and 4 show the outline of each example and a list of evaluation results.

1 is a schematic cross-sectional view showing an electrophotographic photosensitive member according to an embodiment. It is a schematic sectional drawing which shows the electrophotographic photoreceptor which concerns on other embodiment. It is a schematic sectional drawing which shows the electrophotographic photoreceptor which concerns on other embodiment. It is a schematic sectional drawing which shows the electrophotographic photoreceptor which concerns on other embodiment. 1 is a schematic configuration diagram illustrating an image forming apparatus according to an embodiment. It is a schematic block diagram which shows the image forming apparatus which concerns on other embodiment. It is a schematic block diagram which shows the image forming apparatus which concerns on other embodiment. It is a schematic block diagram which shows the process cartridge which concerns on embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Conductive base material 2 Undercoat layer 3 Photosensitive layer 4 Charge generation layer 5 Charge transport layer 6 Protective layer 7 Electrophotographic photosensitive member 8 Charging device 9 Power source 10 Exposure device 11 Developing device 12 Transfer device 13 Cleaning device 14 Static eliminator 15 Fixing Apparatus 100 image forming apparatus 110 image forming apparatus 200 image forming apparatuses 201a to 201d electrophotographic photosensitive members 202a to 202d charging roll 203 laser light sources 204a to 204d developing devices 205a to 205d toner cartridge 206 driving roll 207 tension roll 208 backup roll 209 intermediate transfer Belts 210a to 210d Primary transfer roll 212 Transfer roll 213 Secondary transfer roll 214 Fixing rolls 215a to 215d Cleaning device 216 Cleaning blade 220 Case 230 Transfer medium 300 Process Cartridge 301 housing 303 rail 305 opening 307 electrophotographic photoreceptor 311 a developing device 312 transferring device 313 cleaning unit 314 discharger 315 fixing device

Claims (10)

An undercoat layer and a photosensitive layer are sequentially laminated on a conductive support;
An electrophotographic photoreceptor, wherein the undercoat layer is composed of two or more layers, and each of the two or more undercoat layers contains metal oxide particles.   Of the two or more undercoat layers, the secondary particle diameter of the metal oxide particles contained in the undercoat layer closest to the conductive support is A (1), the lowest farthest from the conductive support. 2. The electrophotographic photosensitive member according to claim 1, wherein A (1) <A (2) when the secondary particle diameter of the metal oxide particles contained in the pulling layer is A (2). body.   Of the two or more undercoat layers, the secondary particle diameter of the metal oxide particles contained in the undercoat layer closest to the conductive support is A (1), the lowest farthest from the conductive support. 3. A (1) ≦ 0.9 × A (2), where A (2) is the secondary particle diameter of the metal oxide particles contained in the pulling layer. The electrophotographic photoreceptor described in 1. The electrophotographic photosensitive member according to any one of claims 1 to 3, wherein the two or more undercoat layers satisfy the following formulas (1) to (3).
Formula (1): a (1)> a (2)>... A (n-1)> a (n)
Formula (2): b (1) <b (2) <... B (n−1) <b (n)
Formula (3): c (1)> c (2)>... C (n-1)> c (n)
(However, in the formulas (1) to (3), a (1), a (2),..., A (n-1), a (n) are the first from the closest to the conductive support. 2,..., N-1 and n, the thickness of the effective photosensitive region center of the undercoat layer, b (1), b (2),... B (n−1), b (N) is the effective photosensitive region end film thickness of the first, second,..., N−1, nth subbing layer from the side closer to the conductive support, and c (1), c (2), ... c (n-1), c (n) are the volumes of the first, second, ... n-1st, nth undercoat layers from the side closer to the conductive support. (Where n represents the total number of undercoat layers and is an integer of 2 or more) The volume resistivity of the undercoat layer is 1.0 × 10 ¹⁵ (Ω · cm) ≧ c (1)> c (2)>... C (n−1)> c (n) ≧ 1.0 The electrophotographic photosensitive member according to claim 4, wherein x 10 ⁸ (Ω · cm) is satisfied.   6. The electrophotographic photosensitive member according to claim 1, wherein the metal oxide particles contained in the two or more undercoat layers contain the same metal.   7. The electrophotographic photoreceptor according to claim 1, wherein the metal oxide particles contained in the two or more undercoat layers are subjected to silane coupling treatment.   The electrophotographic photosensitive member according to claim 1, wherein two or more undercoat layers have the same composition. The electrophotographic photosensitive member according to any one of claims 1 to 8,
Selected from charging means for charging the electrophotographic photosensitive member, electrostatic latent image forming means for exposing the electrophotographic photosensitive member to form an electrostatic latent image, and developing means for developing the electrostatic latent image with toner. And one kind
And a process cartridge which is detachable from the main body of the image forming apparatus. The electrophotographic photosensitive member according to any one of claims 1 to 8,
Charging means for charging the electrophotographic photoreceptor;
Electrostatic latent image forming means for exposing the electrophotographic photosensitive member to form an electrostatic latent image;
Developing means for developing the electrostatic latent image with toner;
Transfer means for transferring the toner image to a transfer medium;
An image forming apparatus comprising:

Images