JP2013097300A - Electrophotographic photoreceptor, process cartridge, and image forming apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor that is used in an image forming apparatus employing an electrophotographic system, includes a photosensitive layer using a charge generating material formed without a pigment dispersion system, provides high image quality to be obtained by the photosensitive layer, and has a long life; and a process cartridge and an image forming apparatus that use the electrophotographic photoreceptor to provide high image quality and have a long life.SOLUTION: An electrophotographic photoreceptor is formed by laminating at least an undercoat layer 11, a charge generating layer 120 including a charge generating material, and a charge transfer layer 121 including a charge transfer material on a conductive support 10 in this order close from the conductive support. The charge generating material includes a compound having a tetrabenzoporphyrin skeleton.

Description

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

  In general, according to the electrophotographic method, a latent image is formed on an electrophotographic photosensitive member (hereinafter also referred to as an image carrier) such as a photoconductive substance, and the electrostatic latent image is charged with toner. To form a visible image, and finally transfer the formed toner visible image to a recording medium such as paper, then fix it on the transfer medium with heat, pressure, solvent gas, etc. to form an output image ing.

  In such image formation, a two-component development method using frictional charging by stirring and mixing the toner and the carrier and a method of charging the toner without using a carrier by a method of charging the toner for visualization. It is roughly divided into a one-component development system. This one-component development method is further classified into a magnetic one-component development method and a non-magnetic one-component development method depending on whether or not a magnetic force is used to hold toner on the developing roller.

Conventionally, in a copying machine that requires high speed and image reproducibility, or a multi-function machine based on a copying machine, the requirements for charging stability of toner, start-up property, long-term stability of image quality, etc. Many component development methods are employed. On the other hand, one-component development systems are often used in small printers, facsimiles, and the like, which have great demands for space saving and cost reduction.
In recent years, in any of the development methods, the colorization of output images has progressed, and the demand for higher image quality and stabilization of image quality has become stronger than ever. In order to achieve such high image quality, the average particle size of the toner is reduced, the particle shape has no angular portion, and the toner has a more round shape.

  In addition, an electrophotographic image forming apparatus is generally charged uniformly while rotating a drum-shaped or belt-shaped electrophotographic photosensitive member regardless of the development method, and electrophotographic with a laser beam or the like. A latent image pattern is formed on the photosensitive member, the latent image pattern is visualized with toner (toner image), and transferred onto a recording medium. Then, the toner component that has not been transferred remains on the electrophotographic photosensitive member after the toner image is transferred to the recording medium. If these residuals are conveyed to the charging process as they are, the electrification of the electrophotographic photosensitive member is prevented from being uniformly charged. Therefore, if necessary, the toner remaining on the electrophotographic photosensitive member after the transfer process is removed. Then, it is removed by a cleaning means such as a cleaning blade, and the surface of the electrophotographic photosensitive member is sufficiently cleaned, and then charging is performed.

The electrophotographic photoreceptors used in these electrophotographic apparatuses are generally roughly classified into inorganic photosensitive layers such as amorphous silicon and selenium, and organic photosensitive layers such as polysilane and phthalopolymethine.
In the market, an image carrier using an organic photosensitive layer is often used from the viewpoint of safety of a substance itself, ease of production, and cost.
In general, an image carrier using an organic photosensitive layer is formed by sequentially repeating a plurality of layers having different functions on the surface of a substrate such as a conductive cylinder by the number of layers that need to be applied and dried. And create.
Among them, the functionally separated type laminated organic photoconductor in which a charge generation layer that generates a charge upon exposure and a charge transport layer that transports a charge are stacked is excellent in terms of electrophotographic characteristics such as sensitivity, chargeability, and repeated stability. Various proposals have been made and put into practical use.

The charge generation layer of a conventional general electrophotographic photoreceptor is formed by applying and drying a dispersion in which a charge generation material is dispersed in a solution in which a binder resin is dissolved in an organic solvent.
It has been found that the dispersion state of the charge generating material in this dispersion has a great influence on the electrical characteristics and image characteristics of the electrophotographic photoreceptor.
In general, since the charge generation material tends to aggregate in the dispersion, it is preferable to stabilize and maintain a good dispersion state of the charge generation material over a long period of time when an electrophotographic photosensitive member is obtained. It is important for obtaining excellent electrical characteristics and image characteristics.
In particular, when there are coarse particles that are poorly dispersed in the dispersion due to agglomeration of charge generating substances, the electrical characteristics become unstable when the electrophotographic photoreceptor having the photosensitive layer formed thereby is used repeatedly. In some cases, a problem such as occurrence of fogging of black spots or the like occurs on the background portion of the copy image.
In addition, if the dispersion state of the charge generating material in the dispersion liquid is likely to become unstable during storage, the storage period (life) of the dispersion liquid is shortened, so that an electron capable of obtaining a good printed image is obtained. When manufacturing a photographic photosensitive member, the cost was increased, which was a problem.

Therefore, in Patent Document 1, Patent Document 2, Patent Document 3, and Patent Document 4, in order to stabilize the good dispersion state of the charge generation material in the dispersion liquid over a long period, A method of adding an auxiliary agent has been proposed.
In Patent Document 5, hydrogen on four aromatic rings (6-membered ring) constituting the phthalocyanine ligand of metal phthalocyanine is substituted with a specific substituent (alkyl group, alkoxy group, aryloxy group), A dispersion for forming a photosensitive layer using soluble phthalocyanine having improved solubility in an organic solvent as a dispersion aid has been proposed.

  Patent Document 6 discloses a dispersion for forming a photosensitive layer using a soluble phthalocyanine compound obtained by treating a phthalocyanine compound with an organometallic compound having a hydrolyzable functional group as a dispersion aid. Has been proposed.

  However, even in the dispersion liquid to which the dispersion aid described in Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, Patent Document 5, and Patent Document 6 is added, the charge in the dispersion liquid It was not possible to stabilize and maintain a good dispersion state of the generated substance for a long period of time, and an electrophotographic photosensitive member formed from such a dispersion was not yet sufficient.

  On the other hand, from the viewpoint of converting light energy into electric energy, research on solar cells has been conducted for a long time, and solar cells using single crystal silicon or amorphous silicon have been widely put into practical use. In addition, unlike these inorganic solar cells, research on organic solar cells using organic materials has been actively conducted in order to take advantage of ease of manufacturing and cost. Especially, in recent years, for organic thin film solar cells. Material development is progressing. Although these solar cell materials may be used as a charge generation material for an electrophotographic photosensitive member, what kind of material is suitable for the electrophotographic photosensitive member has not been studied so far.

  The present invention has been made in view of the above-described problems in the prior art, and in an electrophotographic photoreceptor used in an electrophotographic image forming apparatus, a photosensitive material using a charge generation material formed without going through a pigment dispersion system. An object of the present invention is to provide an electrophotographic photosensitive member having a layer and having a high image quality and a long life obtained thereby. Another object of the present invention is to provide a process cartridge and an image forming apparatus having high image quality and long life by using the electrophotographic photosensitive member.

  As a result of intensive studies to achieve the above object, the present inventors have used, as a charge generation material, a compound having a tetrabenzoporphyrin skeleton obtained by thermally converting a precursor soluble in a solvent. By using the fullerene derivative in combination, the problem of the charge generation layer due to the instability of the dispersed state of the phthalocyanine compound fine particles seen in Patent Document 1 to Patent Document 6 is fundamentally avoided, and a high-performance electrophotographic photosensitive member is obtained. It was found that it can be obtained.

（８）少なくとも電子写真感光体、該電子写真感光体を帯電する帯電手段と、該電子写真感光体上の残存トナーをクリーニングするクリーニング手段を有するプロセスカートリッジにおいて、該電子写真感光体が、前記（１）〜（７）のいずれか１項に記載の電子写真感光体であることを特徴とするプロセスカートリッジ。
（９）少なくとも電子写真感光体と、該電子写真感光体を帯電する帯電手段と、電子写真感光体上に静電潜像を形成するための書き込み手段と、トナーにより静電潜像を可視像化する現像手段と、電子写真感光体上のトナー可視像を、中間転写媒体を介してまたは介さずに、記録媒体上へ転写する転写手段と、トナー像を記録媒体に定着固定化する定着手段とを有する画像形成装置において、上記電子写真感光体が、前記（１）〜（７）のいずれか１項に記載の電子写真感光体であることを特徴とする画像形成装置。
（１０）少なくともプロセスカートリッジと、電子写真感光体上に静電潜像を形成するための書き込み手段と、トナーにより静電潜像を可視像化する現像手段と、電子写真感光体上のトナー可視像を、中間転写媒体を介してまたは介さずに、記録媒体上へ転写する転写手段と、トナー像を記録媒体に定着固定化する定着手段とを有する画像形成装置において、上記プロセスカートリッジが、前記（８）に記載のプロセスカートリッジであることを特徴とする画像形成装置。 That is, in order to solve the above problems, the electrophotographic photosensitive member, the process cartridge, and the image forming apparatus according to the present invention specifically have the technical features described in the following (1) to (10).
(1) At least an undercoat layer, a charge generation layer containing a charge generation material, and a charge transfer layer containing a charge transfer material are formed in this order on at least the conductive support from the side close to the conductive support. An electrophotographic photosensitive member, wherein the charge generating material contains a compound having a tetrabenzoporphyrin skeleton.
(2) The electrophotographic photosensitive member according to (1), wherein the charge generation layer contains a silylmethylfullerene compound.
(3) The charge generation layer contains a layer containing at least a compound having a tetrabenzoporphyrin skeleton and a silylmethylfullerene compound and a compound having at least a tetrabenzoporphyrin skeleton from the side close to the conductive support. The electrophotographic photosensitive member as described in (1) or (2) above, wherein a layer containing no silylmethylfullerene compound is formed in this order.
(4) The electrophotographic photosensitive member according to any one of (1) to (3), wherein the undercoat layer contains at least an electron-accepting material and N-type semiconductive particles.
(5) The electrophotographic photosensitive member according to (4), wherein the electron-accepting material is a fullerene derivative.
(6) The electrophotographic photosensitive member according to (5), wherein the fullerene derivative is a silylmethylfullerene compound.
(7) The electrophotographic photosensitive member according to any one of (2) to (6), wherein the silylmethylfullerene compound is a compound represented by the following chemical formula (I):

(8) In a process cartridge having at least an electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, and a cleaning unit for cleaning residual toner on the electrophotographic photosensitive member, A process cartridge, which is the electrophotographic photosensitive member according to any one of 1) to (7).
(9) At least an electrophotographic photosensitive member, a charging unit for charging the electrophotographic photosensitive member, a writing unit for forming an electrostatic latent image on the electrophotographic photosensitive member, and an electrostatic latent image visible with toner Developing means for forming an image, transfer means for transferring a toner visible image on an electrophotographic photosensitive member onto a recording medium with or without an intermediate transfer medium, and fixing and fixing the toner image on the recording medium An image forming apparatus having a fixing unit, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to any one of (1) to (7).
(10) At least a process cartridge, writing means for forming an electrostatic latent image on the electrophotographic photosensitive member, developing means for visualizing the electrostatic latent image with toner, and toner on the electrophotographic photosensitive member In an image forming apparatus having a transfer unit that transfers a visible image onto a recording medium with or without an intermediate transfer medium, and a fixing unit that fixes and fixes a toner image on the recording medium. An image forming apparatus comprising the process cartridge according to (8).

  According to the electrophotographic photosensitive member, the process cartridge, and the image forming apparatus of the present invention, an electrostatic latent image without image disturbance can be formed on the electrophotographic photosensitive member, and the image quality is stably maintained. be able to.

1 is a cross-sectional view of a configuration example of an image forming apparatus of the present invention. It is the figure which showed an example of the process cartridge of this invention. FIG. 3 is an enlarged partial view showing an example of the layer structure of the electrophotographic photosensitive member of the present invention. FIG. 6 is an enlarged partial view showing another example of the layer structure of the electrophotographic photosensitive member of the present invention.

First, the electrophotographic photoreceptor of the present invention will be described.
The electrophotographic photoreceptor of the present invention includes at least an undercoat layer, a charge generation layer containing a charge generation material, and a charge transfer layer containing a charge transfer material on at least a conductive support from the side close to the conductive support. In this order, the charge generating material contains a compound having a tetrabenzoporphyrin skeleton.
When the charge generation layer contains at least a compound having a tetrabenzoporphyrin skeleton as a charge generation material, the charge generation portion can be formed uniformly and easily, and the electrostatic latent image forming property of the electrophotographic photoreceptor is improved. At the same time, the cost of the electrophotographic photosensitive member can be reduced.

  A typical structure of a material having a tetrabenzoporphyrin skeleton includes an unsubstituted molecule of chemical formula (1), but tetrabenzoporphyrin of chemical formula (1) is insoluble in a solvent.

However, for example, the tetrabenzoporphyrin precursors represented by the chemical formulas (2) to (5) are soluble in a general solvent, and are uniformly mixed with other compositions in the solvent. It is possible to obtain a coating solution for the charge generation layer without having to adjust the thickness.

In addition, as a compound having a tetrabenzoporphyrin skeleton in the present invention, copper, silver, gold, platinum, nickel, calcium, strontium, barium, titanium, manganese, iron, cobalt, nickel, aluminum, gallium, etc. are introduced as a central metal. And a compound having an alkyl group, a phenyl group, a halogen group, a hydroxy group, an amino group, a nitro group, a carboxyl group or the like introduced as a characteristic group, and the like can be appropriately selected and used as necessary. Preferred examples of the central metal in the complex into which the central metal is introduced include titanium and gallium.
In that case, for example, the following tetrabenzoporphyrin precursor can be used as a coating solution for the charge generation layer.

By using the above precursor, a uniform coating film can be formed on the substrate by coating with a general coating solution. Furthermore, these tetrabenzoporphyrin precursors can be converted into low molecular weight diatomic molecules (ethylene in chemical formula (2), chemical formula (3) by reverse Diels-Alder reaction by applying thermal energy even in the absence of a solvent. In this case, hydroxyacetaldehyde) is eliminated to produce tetrabenzoporphyrin of the chemical formula (1), which becomes insoluble in the solvent. Therefore, a uniform charge generation portion can be formed in the electrophotographic photosensitive member, and there is no problem due to segregation or poor dispersion of the charge generation material.
As the temperature at which these tetrabenzoporphyrin precursors are converted into tetrabenzoporphyrins such as chemical formula (1), the conversion temperature varies depending on the type of tetrabenzoporphyrin precursor to be used. Although not possible, it is preferably about 100 ° C. or higher in consideration of removal of volatile components, and about 200 ° C. or lower is preferable in consideration of the heat resistance of the material used for the undercoat layer.

  For the synthesis of these materials having a tetrabenzoporphyrin skeleton, Hidemitsu Uno, Noboru Ono, Journal of Synthetic Organic Chemistry, 2002, 60, 581. In addition, as an example using a uniform coating film, as for FET device creation, P.C. B. Shea, J .; Kanicki, and N.K. Ono, Appl. Phys. Lett. 2005, 87, 173506, p. B. Shea, J .; Kanicki, and N.K. Ono, J .; Appl. Phys. 2005, 98, 014503, S.A. Aramaki, Y. et al. Sakai, and N.K. Ono, Appl. Phys. Lett. 2004, 84, 2085.

The charge generation layer preferably contains a silylmethylfullerene compound.
By using at least a compound having a tetrabenzoporphyrin skeleton and a silylmethylfullerene compound as a charge generation material, it is possible to easily form a charge generation portion with high energy conversion efficiency, and an electrophotographic photoreceptor The electrostatic latent image formability can be improved, and at the same time, the cost of the electrophotographic photosensitive member can be suppressed.

As described above, the use of a compound having a tetrabenzoporphyrin skeleton as a charge generation material greatly contributes to uniform charge generation, but when used in combination with a silylmethylfullerene compound, Generation efficiency can be remarkably improved. Although the mechanism of the photocharge generation efficiency is not always sufficiently clear, it can be generally estimated as follows. First, a compound having a tetrabenzoporphyrin skeleton is likely to donate electrons, while a silylmethylfullerene compound is likely to accept electrons. By using these compounds in combination, a PN junction is formed at the interface, and photocharge transfer is quickly performed. Since the PN junction can be formed in the charge generation layer at a high density, it is considered that the generation efficiency of the photocharge is improved.
As the silylmethylfullerene compound, a compound represented by the chemical formula (I) is preferable as described later.

The electrophotographic photosensitive member according to the present invention includes at least a subbing layer, a charge generation layer, and a charge transfer layer including a charge transfer material on the conductive support from the side close to the conductive support. It is an electrophotographic photosensitive member formed in order.
With such a configuration, by independently forming the layer mainly responsible for the charge generation function, the function and configuration can be designed separately from the part responsible for the charge transfer function and the charge injection prevention function. Therefore, a more functional electrophotographic photosensitive member can be obtained.

  The charge generation layer may be only a layer containing at least a compound having a tetrabenzoporphyrin skeleton or only a layer containing at least a compound having a tetrabenzoporphyrin skeleton and a silylmethylfullerene compound. From the side close to the support, a layer containing at least a compound having a tetrabenzoporphyrin skeleton and a silylmethylfullerene compound, a layer containing at least a compound having a tetrabenzoporphyrin skeleton and no silylmethylfullerene compound, Are more preferably formed in this order.

  Since the charge generation layer has a two-layer structure as described above, a PN junction is formed by the combined use of an electron donating material and an electron accepting material, so that the lower layer side of the charge generation layer by application of light energy (ie, exposure) In addition, the charge generation efficiency can be improved, and since the upper layer side of the charge generation layer is composed of a compound having an electron donating tetrabenzoporphyrin skeleton, holes are rapidly supplied to the charge transfer layer. Therefore, it is possible to obtain an electrophotographic photosensitive member that can efficiently form an electrostatic latent image with less exposure energy without causing problems such as charge accumulation.

The preferable content of the compound having a tetrabenzoporphyrin skeleton in the “layer containing at least a compound having a tetrabenzoporphyrin skeleton and a silylmethylfullerene compound” is preferably 50% by mass or more of the total amount of the layer. More preferably, it is 55-75 mass%.
The ratio of the compound having a tetrabenzoporphyrin skeleton and the silylmethylfullerene compound is preferably about 50 to 50 to 75 to 25 in this order.
The preferable content of the compound having a tetrabenzoporphyrin skeleton in the “layer containing at least a compound having a tetrabenzoporphyrin skeleton and not containing a silylmethylfullerene compound” is 80% by mass or more of the total amount of the layer. Is preferable, and it is more preferable that it is 85-99 mass%.
The thickness of the charge generation layer is preferably about 0.05 to 0.5 μm. When the charge generation layer has the two-layer structure as described above, the film thickness of “a layer containing at least a compound having a tetrabenzoporphyrin skeleton and a silylmethylfullerene compound” is 0.03 μm to 0.45 μm. The film thickness of “a layer containing at least a compound having a tetrabenzoporphyrin skeleton and not containing a silylmethylfullerene compound” is preferably 0.02 μm to 0.4 μm.

The undercoat layer preferably contains at least an electron accepting material and N-type semiconductive particles.
By containing the electron-accepting material and the N-type semiconductor particles in the subbing tank, the negative component of the charge generated on the lower layer side of the subbing layer and the charge generation layer does not accumulate, and the subbing layer side can be quickly The high-contrast electrostatic latent image can be formed.
The electron accepting material is preferably a fullerene derivative.
By using fullerene derivatives as electron-accepting materials, the energy gap between the undercoat layer and the lower layer of the charge generation layer can be reduced, so that the negative component of charge generated by exposure accumulates at the interface. Is not generated over a long period of time, so that the quality of the electrostatic latent image can be maintained.

Examples of the fullerene derivative include the compounds shown below, but silylmethylfullerene compounds are preferable, and compounds represented by the following chemical formula (I) are particularly preferable.

  The packing structure of the compound represented by the chemical formula (I) has a size that allows the compound having a tetrabenzoporphyrin skeleton to easily enter the gap, so that the lower layer of the charge generation layer can easily form a column structure, and the PN junction surface is more Since it is formed efficiently, it is possible to obtain a highly sensitive electrophotographic photosensitive member that requires less light energy for forming a latent image.

[Explanation of terms]
Prior to the description of the embodiments, terms will be described.
Examples of the image forming apparatus include a printer, a facsimile, a copying apparatus, a plotter, and a complex machine of these.

  The recording medium is a medium such as paper, thread, fiber, leather, metal, plastic, glass, wood, ceramics. In the following description, the recording medium is assumed to be paper.

  Image formation refers to the application of images such as letters, figures, and patterns to a recording medium, the electrostatic latent image is visualized with colored or non-colored powder (for example, toner), and an intermediate transfer medium is used as necessary. This means that this is transferred and fixed on a recording medium.

  Colored or non-colored powders include single resin powders, composite powders, single or multiple color materials, composites of resin and color materials, and powders obtained by adding a wax component or an inorganic material to these. Is used as a general term for all powders that can form images, such as toners including functional powders that are highly controlled in shape, such as gloss-suppressing powders, gloss-imparting powders, baking powders, and foaming properties. Also includes powder. Below, powder is demonstrated as a toner.

  The process cartridge is an integrated part or all of the components necessary for image formation, and includes at least an electrophotographic photosensitive member. In addition, charging for applying a predetermined potential to the electrophotographic photosensitive member, writing for forming an electrostatic latent image, development for forming the electrostatic latent image on the electrophotographic photosensitive member into a toner image, on the electrophotographic photosensitive member In order to perform transfer for transferring the toner image on the recording medium or intermediate transfer medium, and cleaning for removing the residual toner image on the electrophotographic photosensitive member, all or a part of the necessary constituent members may be included. Good. Moreover, each member is configured in a form that can be arranged so that a necessary process can be performed.

[Image forming apparatus]
FIG. 1 shows a cross-sectional view of one configuration example of the image forming apparatus 100 of the present invention. The image forming unit 10 of the image forming apparatus 100 includes electrophotographic photoreceptors 1Y, 1M, 1C, and 1K. The electrophotographic photoreceptors 1Y, 1M, 1C, and 1K are provided along the conveyance direction of the intermediate transfer belt 5. Hereinafter, the electrophotographic photoreceptors 1Y, 1M, 1C, and 1K are collectively referred to as the electrophotographic photoreceptor 1. The electrophotographic photoreceptors 1Y, 1M, 1C, and 1K can carry images of toners of various colors (for example, yellow, magenta, cyan, and black) and are electrophotographic photoreceptors of the present invention. The image is written on the electrophotographic photosensitive member 1 by the writing device 3.
Around the drum-shaped electrophotographic photoreceptors 1Y, 1C, 1M, and 1K, a charging device 2, a writing device 3, a developing device 4, an intermediate transfer belt 5, and a cleaning device 6 are arranged, respectively.

  The intermediate transfer belt 5 is wound around rollers 50 and 51. Inside the intermediate transfer belt 5, primary transfer rollers 52 </ b> Y, 52 </ b> C, 52 </ b> M, and 52 </ b> K as primary transfer units are arranged corresponding to the respective image carriers 1. Further, a secondary transfer roller 53 as a secondary transfer unit for collectively transferring the superimposed image on the intermediate transfer belt 5 onto the recording medium is disposed at a position facing the roller 51.

[Electrostatic latent image forming means]
The electrostatic latent image forming means is not particularly limited as long as it is a means for forming the electrostatic latent image on the electrophotographic photosensitive member 1 after charging the electrophotographic photosensitive member 1 using the charging device 2. Can be appropriately selected according to the purpose.

The charging can be performed by applying a voltage to the surface of the electrophotographic photoreceptor 1 using the following charging device 2.
The charging device 2 is not particularly limited and may be appropriately selected depending on the purpose. For example, the charging device 2 may be a known contact having a conductive or semiconductive roll, brush, film, rubber blade, or the like. Examples thereof include a charging device, a non-contact charging device using corona discharge such as corotron and scorotron. A charging potential can be secured in a relatively low applied voltage range, power consumption can be suppressed, and the amount of generated ozone can be suppressed, so that a conductive or semiconductive roll is brought into contact with the image carrier. A charging device having a charging roller that performs either charging or proximity charging is preferable. In addition, when using a charging means having a charging roller of either contact charging or proximity charging, use a soft contact charging roller or arrange a pressure member so that a large pressing force is not applied to the contact portion. It is more preferable to adopt a charging means configuration that is not provided.
Further, the charging device 2 preferably has a voltage applying means for applying a voltage having an AC component.

The writing device 3 can be performed, for example, by exposing the surface of the electrophotographic photosensitive member imagewise using a writing exposure device.
The writing exposure device is not particularly limited as long as the surface of the electrophotographic photosensitive member charged by the charging device 2 can be exposed like an image to be formed, and can be appropriately selected according to the purpose. However, various writing exposure apparatuses such as a copying optical system, a rod lens array system, a laser optical system, a liquid crystal shutter optical system, and an LED optical system can be used.
Note that an optical backside system that performs imagewise writing exposure from the backside of the electrophotographic photosensitive member may be employed.

[Development means]
The developing device 4 is a unit that develops the electrostatic latent image formed on the electrophotographic photosensitive member 1 using a developer to form a visible image, and includes a developing sleeve and a developer stirring and conveying mechanism. Have.
The developing sleeve carries a developer and conveys the developer to a position facing the image carrier.
A developing gap defined as a gap is formed between the electrophotographic photosensitive member and the developing sleeve.
The development gap is a substantially uniform gap in consideration of the pumping amount of the developer, the strength of the magnetic field for holding the developer on the developing sleeve, the magnetization of the carrier in the developer, the rotation speed of the developing sleeve, and the like. However, the average value is preferably about 0.2 to 0.4 mm.
The developing device is not particularly limited as long as it has these configurations, and can be appropriately selected from known ones. For example, the developer is accommodated, and the developer is contained in the electrostatic latent image. Those having at least a developing device which can be applied in a contact or non-contact manner are preferable.

[Developer]
The developer is not particularly limited and may be appropriately selected depending on the intended purpose. A two-component developer including a toner and a carrier is preferable.

The toner is not particularly limited and may be appropriately selected depending on the intended purpose. The average circularity, which is an average value of the circularity SR represented by the following formula (1), is 0.93 to 1.00. Is preferable, and 0.95-0.99 is more preferable.
This average circularity is an index of the degree of unevenness of toner particles, and indicates 1.00 when the toner is a perfect sphere, and the average circularity becomes smaller as the surface shape becomes more complicated.
[Formula 1]
Circularity SR = perimeter of circle having area equal to projected area of toner particles / perimeter of toner particles
... Formula (1)

  There is no restriction | limiting in particular as a mass mean particle diameter (D4) of the said toner, Although it can select suitably according to the objective, 3 micrometers-10 micrometers are preferable, and 4 micrometers-8 micrometers are more preferable. In this range, since the toner particles have a sufficiently small particle size with respect to the minute latent image dots, the dot reproducibility is excellent. When the mass average particle diameter (D4) is less than 3 μm, phenomena such as a decrease in transfer efficiency and a decrease in blade cleaning properties may occur, and when it exceeds 10 μm, it is difficult to suppress scattering of characters and lines. is there.

[Cleaning means]
The cleaning device 6 is not particularly limited as long as it is a device that cleans the surface of the electrophotographic photosensitive member, and can be appropriately selected according to the purpose. For example, a cleaning device that can realize the device is given. Among them, it is preferable to have a cleaning blade for cleaning the surface of the electrophotographic photosensitive member.
In general, as an image carrier cleaning method, in addition to the method using the cleaning blade, an electrostatic cleaning method using a brush to which a voltage is applied so as to be opposite in polarity to the toner remaining on the image carrier. Is mentioned.
In addition, after transferring the toner image on the electrophotographic photosensitive member to the cleaning device, the entire surface of the electrophotographic photosensitive member is exposed by irradiating light from a light emitting element disposed in the main body of the image forming apparatus. You may have the light guide member which forms the light guide for making (exposure before cleaning). With such a configuration, the history of the electrostatic latent image can be erased and the electrophotographic photosensitive member can be uniformly charged, so that a stable image with higher image quality can be reliably provided. .

[Process cartridge]
Next, each electrophotographic photosensitive member 1, the developing device 4 and the like can be integrally configured as a process cartridge that is detachable from the main body of the image forming apparatus. FIG. 2 shows a configuration example of the process cartridge 300 of this embodiment. However, the color code is omitted.
The above-described electrophotographic photoreceptor 1, charging device 2, developing device 4, and cleaning device 6 are accommodated integrally in a process cartridge 300.
The charging device 2 has a charging roller 20 as a charging member.
The developing device 4 includes a developing sleeve 40 and developer agitating and conveying members 41 and 42 for agitating and conveying the developer in the developing casing for circulation. A toner replenishing section (not shown) is provided above the developer stirring and conveying member 42.
The cleaning device 6 has a cleaning blade 60 that contacts the surface of the electrophotographic photosensitive member 1 in the leading direction. In addition, after transferring the toner image on the electrophotographic photosensitive member to the cleaning device, the entire surface of the electrophotographic photosensitive member is exposed by irradiating light from a light emitting element disposed in the main body of the image forming apparatus. It has a light guide member 9 that forms a light guide for (exposure before cleaning).

  Since the image forming apparatus and the process cartridge of the present invention use the electrophotographic photosensitive member of the present invention, it is possible to reliably provide a stable image.

[Electrophotographic photoconductor]
3 and 4 are partially enlarged views (schematic diagrams) of an example of the electrophotographic photoreceptor 1. The electrophotographic photoreceptor 1 includes a conductive support 10, an undercoat layer 11, and a photosensitive layer 12. The photosensitive layer 12 includes a charge generation layer 120 and a charge transfer layer 121. In FIG. 3, the charge generation layer 120 is a layer containing at least a compound having a tetrabenzoporphyrin skeleton. In FIG. 4, the charge generation layer 120 includes a layer 1200 containing at least a compound having a tetrabenzoporphyrin skeleton and a silylmethylfullerene compound, and at least a tetrabenzoporphyrin skeleton from the side close to the conductive support 10. A layer 1201 containing the compound having the above and not containing the silylmethyl fullerene compound is formed in this order.

[Conductive support]
As the conductive support 10 used in the electrophotographic photosensitive member 1, one having a volume resistance of 1.0 × 10 ¹⁰ Ω · cm or less is preferably used, and can be appropriately selected according to the purpose. , Metal such as aluminum, nickel, chromium, nichrome, copper, gold, silver, platinum, metal oxide such as tin oxide, indium oxide, etc., coated with plastic, tempered glass, etc. by vapor deposition or sputtering, or aluminum, Examples of the pipe include aluminum alloy, nickel, stainless steel, etc., which are formed into a drum shape by a method such as extrusion and drawing, and then subjected to surface treatment such as cutting, finishing, and polishing. From the standpoints of alignment accuracy during image formation and dimensional stability, the support 10 is preferably a hard tube or a thin tube having sufficient tensile strength.

  There is no restriction | limiting in particular as a diameter of the support body 10, Although it can select suitably according to the objective, 20 mm-150 mm are preferable, 24 mm-100 mm are more preferable, 28 mm-70 mm are especially preferable. If the diameter is less than 20 mm, it may be physically difficult to arrange the charging, exposure, development, transfer, and cleaning steps around the electrophotographic photosensitive member. If the diameter exceeds 150 mm, the image forming apparatus 100 may become large.

[Underlayer]
The undercoat layer 11 is not particularly limited, and may be a single layer or a plurality of layers. For example, (1) a resin-based component, (2) an electron-accepting material, and an N-type Examples thereof include those containing semiconductive particles and a resin as main components, and (3) a metal oxide film obtained by chemically or electrochemically oxidizing the surface of a conductive support. Among these, those containing an electron accepting material, N-type semiconductive particles, and a resin as main components are preferable.

As the electron-accepting material, any material can be used as long as desired characteristics can be obtained, but materials having high affinity with N-type semiconductor particles are preferably used.
A compound having an anthraquinone structure having a hydroxyl group as a basic skeleton is preferable, and a hydroxyanthraquinone compound, an aminohydroxyanthraquinone compound, and the like can be preferably used.
Specifically, 1,2-dihydroxy-9,10-anthraquinone, 1,4-dihydroxy-9,10-anthraquinone, 1,5-dihydroxy-9,10-anthraquinone, 1,2,4-trihydroxy- 9,10-anthraquinone, 1-hydroxyanthraquinone, 2-amino-3-hydroxyanthraquinone, 1-amino-4-hydroxyanthraquinone and the like can be mentioned.
Further, fullerene derivatives can also be used as an electron accepting material, and any of phenyl C ₆₁ butyric acid methyl ester, phenyl C ₆₁ butyric acid butyl ester, phenyl C ₆₁ butyric acid isobutyl ester and the like can be preferably used.
Furthermore, among the fullerene derivatives, silylmethylfullerene compounds have a good charge generation function when combined with the charge generation layer of the present invention, and among them, the use of an electron accepting material having the structure of the chemical formula (I) is preferable.

The N-type semiconductor particles are not particularly limited, and are, for example, metal oxides such as zinc oxide, tin dioxide, indium oxide, and ITO (for example, In ₂ O ₃ : SnO ₂ = 90: 10 [mass%]). Or the particle | grains which processed the base-material particle | grain surface of the inorganic oxide with these materials are mentioned.

The resin is not particularly limited, and examples thereof include thermoplastic resins such as polyamide, polyvinyl alcohol, casein, and methyl cellulose; thermosetting resins such as acrylic, phenol, melamine, alkyd, unsaturated polyester, and epoxy. These may be used individually by 1 type and may use 2 or more types together.
The N-type semiconductor particles in the undercoat layer are preferably about 40 to 80% by mass with respect to the total amount of the undercoat layer.
The electron-accepting material is preferably about 1 to 5% by mass of the mass of the N-type semiconductor particles.
Since it is preferable to change the thickness of the undercoat layer 11 depending on the type and combination of materials used, it is not possible to determine the range in general. However, the thickness of the undercoat layer 11 is preferably about 0.5 μm to 30 μm. In order to more quickly prevent the charge generated in the charge generation layer while preventing the charge injection more surely, about 2 μm to 20 μm is more preferable.

[Photosensitive layer]
The photosensitive layer 12 is not particularly limited as long as it is within the range specified in the present invention, and can be appropriately selected according to the purpose.
For example, a normal layer type having a charge transfer layer containing a charge transfer material on a charge generation layer containing a charge generation material, or a reverse layer type having a charge generation layer on a charge transfer layer can be mentioned.
Moreover, an appropriate amount of a plasticizer, an antioxidant, a leveling agent or the like can be added to each layer as necessary.
There is no restriction | limiting in particular as thickness of the said photosensitive layer 12, According to the objective, it can select suitably, 10-50 micrometers is preferable.
The total thickness of the undercoat layer 11 and the photosensitive layer 12 preferably satisfies the range of 20 to 60 μm.
When these relationships are satisfied, a uniform visible image can be formed over a long period of time, so that a stable image forming apparatus with little temporal variation can be provided. If the thickness is less than 20 μm, it may be difficult to ensure electrical uniformity as an electrophotographic photosensitive member, and if it exceeds 60 μm, the electrostatic latent image resolution may be reduced. This is not preferable.

It is essential that the charge generation material in the charge generation layer contains a compound having a tetrabenzoporphyrin skeleton.
Examples of compounds having a tetrabenzoporphyrin skeleton include unsubstituted tetrabenzoporphyrin, and copper, silver, gold, platinum, nickel, calcium, strontium, barium, titanium, manganese, iron, cobalt, nickel, aluminum, and gallium as central metals. And the like, and compounds having introduced an alkyl group, phenyl group, halogen group, hydroxy group, amino group, nitro group, carboxyl group or the like as a characteristic group, and the like can be appropriately selected and used as necessary. .

The charge generation layer preferably contains a silylmethylfullerene compound.
Examples of the silylmethyl fullerene compound include compounds in which a part of the fullerene surface is modified with a silyl group-substituted alkyl group such as a dimethylphenylsilylmethyl group or a 9-anthracenyldimethylsilylmethyl group. A silylmethylfullerene compound having the structure (I) is preferably used.

  As described above, the silylmethylfullerene compound is self-assembled by heating, and a compound having a tetrabenzoporphyrin skeleton is taken in the gap to form a large number of PN junction surfaces. Electric charges are generated with respect to the input with extremely high efficiency, and a clear electrostatic latent image contrast can be obtained even with a smaller writing energy. In particular, the compound of the chemical formula (I) can be used very preferably because the size of the gap when self-assembled is close to the size of the tetrabenzoporphyrin skeleton, so that a PN junction surface can be formed at a high density. .

  Also, for example, monoazo pigments, bisazo pigments, trisazo pigments, azo pigments such as tetrakisazo pigments, triarylmethane dyes, thiazine dyes, oxazine dyes, xanthene dyes, cyanine dyes, styryl dyes, Organic pigments or dyes such as pyrylium dyes, quinacridone pigments, indigo pigments, perylene pigments, polycyclic quinone pigments, bisbenzimidazole pigments, indanthrone pigments, squarylium pigments, phthalocyanine pigments; cadmium sulfide In addition, a charge generation material such as an inorganic material such as zinc oxide or titanium oxide may be used in combination. When these charge generation materials are used in combination, the amount is preferably less than the same amount as the compound having a tetrabenzoporphyrin skeleton on a mass basis so as not to inhibit the effects of the present invention. More preferably.

  Examples of the charge transfer material in the charge transfer layer include anthracene derivatives, pyrene derivatives, carbazole derivatives, tetrazole derivatives, metallocene derivatives, phenothiazine derivatives, pyrazoline compounds, hydrazone compounds, styryl compounds, styryl hydrazone compounds, enamine compounds, butadiene compounds, Examples include distyryl compounds, oxazole compounds, oxadiazole compounds, thiazole compounds, imidazole compounds, triphenylamine derivatives, phenylenediamine derivatives, aminostilbene derivatives, and triphenylmethane derivatives. These may be used individually by 1 type and may use 2 or more types together.

The binder resin in the photosensitive layer is electrically insulating, and known thermoplastic resins, thermosetting resins, photocurable resins, photoconductive resins, and the like can be used.
Examples of the binder resin include polyvinyl chloride, polyvinylidene chloride, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinyl acetate-maleic anhydride copolymer, ethylene-vinyl acetate copolymer, polyvinyl butyral, Polyvinyl acetal, polyester, phenoxy resin, (meth) acrylic resin, polystyrene, polycarbonate, polyarylate, polysulfone, polyethersulfone, ABS resin and other thermoplastic resins, phenol resin, epoxy resin, urethane resin, melamine resin, isocyanate Examples thereof include thermosetting resins such as resins, alkyd resins, silicone resins, thermosetting acrylic resins, polyvinyl carbazole, polyvinyl anthracene, and polyvinyl pyrene. These may be used individually by 1 type and may use 2 or more types together.

Examples of the antioxidant in the photosensitive layer include phenolic compounds, paraphenylenediamines, hydroquinones, organic sulfur compounds, and organic phosphorus compounds.
Examples of the phenol compound include 2,6-di-t-butyl-p-cresol, butylated hydroxyanisole, 2,6-di-t-butyl-4-ethylphenol, stearyl-β- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylene-bis- (4-methyl-6-t-butylphenol), 2,2'-methylene-bis- (4-ethyl- 6-t-butylphenol), 4,4′-thiobis- (3-methyl-6-tert-butylphenol), 4,4′-butylidenebis- (3-methyl-6-tert-butylphenol), 1,1,3 -Tris- (2-methyl-4-hydroxy-5-t-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-t-butyl-4-hydroxy Ben ) Benzene, tetrakis- [methylene-3- (3 ′, 5′-di-t-butyl-4′-hydroxyphenyl) propionate] methane, bis [3,3′-bis (4′-hydroxy-3 ′) -T-butylphenyl) butyric acid] cricol ester, tocopherols and the like.

Examples of the paraphenylenediamines include N-phenyl-N′-isopropyl-p-phenylenediamine, N, N′-di-sec-butyl-p-phenylenediamine, N-phenyl-N-sec-butyl- Examples include p-phenylenediamine, N, N′-di-isopropyl-p-phenylenediamine, N, N′-dimethyl-N, N′-di-t-butyl-p-phenylenediamine, and the like.
Examples of the hydroquinones include 2,5-di-t-octyl hydroquinone, 2,6-didodecyl hydroquinone, 2-dodecyl hydroquinone, 2-dodecyl-5-chlorohydroquinone, 2-t-octyl-5-methyl. Examples include hydroquinone and 2- (2-octadecenyl) -5-methylhydroquinone.
Examples of the organic sulfur compounds include dilauryl-3,3′-thiodipropionate, distearyl-3,3′-thiodipropionate, ditetradecyl-3,3′-thiodipropionate, and the like. .
Examples of the organic phosphorus compounds include triphenylphosphine, tri (nonylphenyl) phosphine, tri (dinonylphenyl) phosphine, tricresylphosphine, tri (2,4-dibutylphenoxy) phosphine, and the like.

These compounds are known as antioxidants such as rubbers, plastics and fats and oils, and commercially available products can be easily obtained.
As addition amount of the said antioxidant, 0.01 mass%-10 mass% are preferable with respect to the total mass of the layer to add.

  As the plasticizer in the photosensitive layer, those used as plasticizers for general resins such as dibutyl phthalate and dioctyl phthalate can be used as they are, and the amount used is 0 parts by mass with respect to 100 parts by mass of the binder resin. About 30 parts by mass is appropriate.

  Further, a leveling agent may be added to the photosensitive layer. Examples of the leveling agent include silicone oils such as dimethyl silicone oil and methylphenyl silicone oil; polymers having a perfluoroalkyl group in the chain or oligomers. The amount of the leveling agent used is preferably 0 to 1 part by mass with respect to 100 parts by mass of the binder resin.

[Surface coating layer]
The electrophotographic photoreceptor of the present invention may be provided with a surface coating layer as necessary.
The surface coating layer is not particularly limited, but for example, a polymer having a mechanical strength higher than that of the photosensitive layer or a material in which an inorganic filler is dispersed in the polymer is preferable.
The resin used for the surface coating layer is not particularly limited and may be either a thermoplastic resin or a thermosetting resin, but has high mechanical strength and the ability to suppress wear due to friction with the cleaning blade. Very high thermosetting resins are preferred.
If the surface coating layer is thin, there is no problem even if it does not have the charge transfer capability, but if the surface coating layer without the charge transfer capability is formed thick, the sensitivity of the photoreceptor decreases, the potential increases after exposure, Since the residual potential is likely to increase, it is preferable to include the above-described charge transfer substance in the surface coating layer or to use a polymer having charge transfer capability as the polymer used in the surface coating layer.

The resin used for the surface coating layer is preferably one that is transparent to the writing light during image formation and excellent in insulation, mechanical strength, and adhesion. For example, ABS resin, ACS resin, olefin-vinyl monomer copolymer Polymer, chlorinated polyether, allyl resin, phenol resin, polyacetal, polyamide, polyamideimide, polyacrylate, polyallylsulfone, polybutylene, polybutylene terephthalate, polycarbonate, polyethersulfone, polyethylene, polyethylene terephthalate, polyimide, acrylic resin, Polymethylbenten, polypropylene, polyphenylene oxide, polysulfone, polystyrene, AS resin, butadiene-styrene copolymer, polyurethane, polyvinyl chloride, polyvinylidene chloride, epoxy resin, etc. And the like.
These polymers are not particularly limited and may be thermoplastic resins, but in order to increase the mechanical strength of the polymer, crosslinks having a polyfunctional acryloyl group, carboxyl group, hydroxyl group, amino group, etc. It is preferable to crosslink with an agent to form a thermosetting resin. In this way, the mechanical strength of the surface coating layer increases, and wear due to friction with the cleaning blade can be greatly reduced.

[Image formation process]
A series of processes for forming an image will be described using a negative-positive process with reference to FIG. In the case of contents common to all electrophotographic photosensitive members and developing devices, the electrophotographic photosensitive member is simply denoted by reference numeral 1 and the developing device is denoted by reference numeral 4.
The electrophotographic photoreceptor 1 is neutralized by a neutralizing lamp (not shown) or the like, and is uniformly negatively charged by a charging device 2 having a charging member described later.
When the electrophotographic photosensitive member 1 is charged by the charging device 2, a voltage having an appropriate magnitude suitable for charging the electrophotographic photosensitive member 1 to a desired potential from the voltage applying device described later to the charging member. Alternatively, a charging voltage obtained by superimposing an AC voltage thereon is applied.
The charged electrophotographic photosensitive member 1 forms a latent image with laser light L irradiated by a writing device 3 such as a laser optical system (the absolute value of the exposed portion potential is lower than the absolute value of the non-exposed portion potential). ) Is performed.
Laser light is emitted from a semiconductor laser, and the surface of the electrophotographic photosensitive member 1 is scanned in the direction of the rotational axis of the electrophotographic photosensitive member 1 by a polygonal polygonal mirror that rotates at high speed.

The electrostatic latent image formed in this way is developed with a developer made of toner particles or a mixture of toner particles and carrier particles supplied onto a developing sleeve 40 as a developer carrying member in the developing device 4. A toner visible image is formed.
At the time of developing the electrostatic latent image, an appropriate voltage or an AC voltage superimposed on the developing sleeve from the voltage applying device to the developing sleeve between the exposed portion and the non-exposed portion of the electrophotographic photosensitive member 1 is developed. A bias is applied.
The toner images formed on the electrophotographic photoreceptors 1Y, 1C, 1M, and 1K corresponding to the respective colors are sequentially superimposed on the intermediate transfer belt 5 by primary transfer rollers 52Y, 52C, 52M, and 52K as primary transfer units. Is transcribed. At this time, it is preferable that a potential having a polarity opposite to the toner charging polarity is applied to the primary transfer roller 52 as a transfer bias. Thereafter, the intermediate transfer belt 5 is separated from the electrophotographic photosensitive member 1 to obtain a transfer image.
The superimposed toner images transferred onto the intermediate transfer belt 5 are collectively transferred by a secondary transfer roller 53 onto a recording medium such as paper fed from the paper feeding device 200.

The recording medium fed from the selected paper feed cassette of the paper feed device 200 is temporarily stopped by the pair of registration rollers to correct the oblique shift, and then to the secondary transfer portion of the secondary transfer roller 53 at a predetermined timing. Be transported.
The recording medium on which the superimposed images are collectively transferred is sent to the fixing device 7 where the toner image is fixed by heat and pressure. After the fixing, the recording medium is discharged and stacked on the discharge tray 8 by a pair of discharge rollers.

The toner particles remaining on the electrophotographic photosensitive member 1 after the primary transfer are removed and collected by the cleaning device 6, and the toner particles remaining on the intermediate transfer belt 5 after the secondary transfer are removed and cleaned by the cleaning device for the intermediate transfer belt. To be recovered.
In this embodiment, the image forming apparatus is configured to perform secondary transfer using the intermediate transfer belt 5, but the toner images of the plurality of electrophotographic photoreceptors 1 are sequentially transferred onto the recording medium while the recording medium is conveyed by the conveying belt. It is good also as a structure which superimposes and transfers to.

  EXAMPLES Next, the present invention will be described in more detail by way of examples. In the examples, the parts indicate parts by mass.

[Evaluation method]
Next, the evaluation method will be described.

  The coating layer thickness (the total of the undercoat layer, the charge generation layer, and the charge transport layer) is an eddy current type film thickness meter (universal type film thickness meter LZ-200, manufactured by Kett Science Laboratory, LHP-20). (NFe) type probe) was measured at 10 locations along the image carrier rotation axis direction and averaged.

  The initial image quality generally refers to the quality of an image formed on the first to fourth sheets. The image quality after 200,000 sheets refers to the quality of the image formed on the 200,000th sheet. Further, the image quality is evaluated by observing the uniformity of dots visually or with a magnifying glass of 25 times. Also, it refers to the quality of the initial image formed on the A4 size text chart. Further, the image quality after 200000 sheets is the quality of an image whose stability was confirmed by performing again after passing 200,000 sheets of A4 size text chart with a pixel density of 5%.

  The visual 2by2 is a visual observation of an image formed on a 2by2 full-tone A4 sheet of 600 dpi and a pixel density of 25%. Here, the 2by2 full-surface tone with a pixel density of 25% is a square image area formed by 4 × 4 pixels, a rectangular image area for 2 × 2 pixels, and a non-image area other than the rectangular image area. By forming an image over the entire surface, an image having a pixel density of 4/16 = 25% is formed.

  The visual solid is a visual observation of an image formed on a full surface with a pixel density of 100%. A full-surface image is an image formed on the entire surface with a pixel density of 100%.

  The visual blank paper is a visual observation of a blank paper on which an image is not formed with a pixel density of 0%.

  The enlargement 2by2 is an image formed on a 2by2 full-tone A4 sheet having a pixel density of 25% and visually observed with a magnifier of 25 times. Note that, when magnifying and observing, the maximum value Rmax of the average value at each measurement point of the dot diameters (area reference circle equivalent diameters) measured at the three positions at both ends and the center in the image width direction (developing roller axial direction) The ratio Rr (Rr = Rmin / Rmax) between [μm] and the minimum value Rmin [μm] was taken and evaluated according to the following criteria.

The evaluation criteria such as ◎ in the table will be described.
<< Visual 2by2 image >>
A: Excellent (level at which unevenness cannot be detected over the entire surface)
○: Level that does not cause any practical problems (level that can detect slight unevenness when viewed side by side with ◎)
△: Practically acceptable level (level that can detect unevenness when viewed side by side with ◎)
×: Cannot be used (can clearly detect unevenness by itself)
≪Visually solid≫
A: Excellent (level at which unevenness cannot be detected over the entire surface)
○: Level that does not cause any practical problems (level that can detect slight unevenness when viewed side by side with ◎)
△: Practically acceptable level (level that can detect unevenness when viewed side by side with ◎)
×: Cannot be used (can clearly detect unevenness by itself)
≪Visual blank paper≫
A: Extremely excellent (level at which abnormal fine lines cannot be detected over the entire surface)
○: Level where there is no problem in practical use (level where dirt can be detected slightly when lined with ◎)
Δ: Practically acceptable level (level at which dirt can be detected when viewed alongside ◎)
×: Cannot be used (contamination can be clearly detected by itself)
≪Enlarged 2by2≫
A: Extremely excellent (dots are very uniform; Rr is 0.9 or more)
○: Level where there is no problem in practical use (there are a few places where there is a difference in dot size for each field of view;
Rr is 0.8 or more and less than 0.9)
Δ: Practically acceptable level (there is a place where there is a difference in dot size for each field of view; Rr
0.6 to less than 0.8)
×: Unusable (sizes of dots in a plurality of areas are clearly different; Rr is less than 0.6)

[Example 1]
<Preparation of electrophotographic photoreceptor 1>
As the conductive cylindrical support, an aluminum cylinder having an outer diameter of 40 mm and a wall thickness of 0.8 mm was used. On this aluminum cylinder, an undercoat layer coating solution, a charge generation layer coating solution, and a charge transfer layer coating solution having the following composition are sequentially applied by dip coating and drying to obtain a 15 μm undercoat layer, A 0.2 μm charge generation layer and an approximately 30 μm charge transfer layer were formed to obtain an electrophotographic photoreceptor 1.

[Coating liquid for undercoat layer]
An undercoat layer coating solution having the following composition was dip-coated on the aluminum cylinder, and then heated and dried at 120 ° C. for 25 minutes to form a 15 μm undercoat layer.
−Coating liquid composition for undercoat layer−
Alkyd resin 6 parts (Beccosol 1307-60-EL, manufactured by Dainippon Ink & Chemicals, Inc.)
Melamine resin 4 parts (Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.)
N-type semiconductor Aluminum-doped zinc oxide 25 parts (Pazet CK, manufactured by Hakusui Tech Co., Ltd.)
Charge accepting material 1,2-dihydroxy-9,10-anthraquinone 0.4 part Titanium oxide 15 parts (CR-EL, manufactured by Ishihara Sangyo Co., Ltd.)
200 parts of methyl ethyl ketone

ポリビニルブチラール ０．１部
（エスレックＢＭ−Ｓ、積水化学工業社製）
テトラヒドロフラン ５０部 [Coating liquid for charge generation layer]
After dip-coating the coating solution for the charge generation layer having the following composition on the undercoat layer, followed by heat drying at 120 ° C. for 20 minutes, the temperature was raised to 180 ° C. at a temperature rising rate of 5 ° C. per minute, By holding for an additional 15 minutes, the tetrabenzoporphyrin precursor was thermally converted to tetrabenzoporphyrin to form a 0.2 μm charge generation layer.
-Coating solution composition for charge generation layer-
2 parts of tetrabenzoporphyrin precursor of formula (2)

Polyvinyl butyral 0.1 part (ESREC BM-S, manufactured by Sekisui Chemical Co., Ltd.)
50 parts of tetrahydrofuran

ビスフェノールＺポリカーボネート １０部
（パンライトＴＳ−２０５０：帝人化成社製）
シリコーンオイル ０．００２部
（ＫＦ−５０、信越化学工業社製）
テトラヒドロフラン １００部 [Coating liquid for charge transfer layer]
A charge transfer layer coating solution having the following composition was dip-coated on the charge generation layer, followed by heating and drying at 135 ° C. for 20 minutes to form a charge transfer layer to obtain an electrophotographic photoreceptor 1. In the dip coating process, the lifting speed and the surrounding atmosphere were adjusted so that the amount of coating liquid deposited was uniform.
-Coating liquid composition for charge transfer layer-
10 parts of charge transfer material (D-1) represented by the following structural formula

Bisphenol Z polycarbonate 10 parts (Panlite TS-2050: manufactured by Teijin Chemicals Ltd.)
0.002 part of silicone oil (KF-50, manufactured by Shin-Etsu Chemical Co., Ltd.)
Tetrahydrofuran 100 parts

The thickness of the coating layer of the obtained electrophotographic photoreceptor 1 was 45.2 μm on average.
The electrophotographic photosensitive member 1 was provided with flanges at both ends.

<Production of process cartridge>
The flanged electrophotographic photosensitive member 1 was incorporated in an imaging unit of Rigoh's imgio MP C4500. The cartridge used was black.

<Confirmation of image quality>
The produced process cartridge was replaced with a black cartridge made by Imagio MP C4500 manufactured by Ricoh, and image evaluation was performed according to the above procedure. The initial setting of the laser output in the model used for the evaluation is 3.5 mJ / m ^{2 on the} basis of the exposure energy.
The evaluation results are shown in Table 1.

[Example 2]
<Preparation of electrophotographic photoreceptor 2>
After dip-coating the coating solution for charge generation layer having the following composition on the undercoat layer, the mixture was heated to 120 ° C. for 20 minutes and then heated to 160 ° C. at a rate of 5 ° C. per minute. The electrophotographic photosensitive member 2 was prepared in the same manner as in Example 1 except that the tetrabenzoporphyrin precursor was thermally converted to tetrabenzoporphyrin by holding for 15 minutes to form a 0.2 μm charge generation layer. Produced.

ポリビニルブチラール ０．１部
（エスレックＢＭ−Ｓ、積水化学工業社製）
テトラヒドロフラン ５０部 -Coating solution composition for charge generation layer-
2 parts of tetrabenzoporphyrin precursor of formula (4)

Polyvinyl butyral 0.1 part (ESREC BM-S, manufactured by Sekisui Chemical Co., Ltd.)
50 parts of tetrahydrofuran

Except that the electrophotographic photosensitive member 2 was used, <Process Cartridge Creation> and <Image Quality Check> were performed in the same manner as in Example 1.
The evaluation results are shown in Table 1.

ポリビニルブチラール ０．１部
（エスレックＢＭ−Ｓ、積水化学工業社製）
テトラヒドロフラン ５０部 [Example 3]
<Preparation of Electrophotographic Photoreceptor 3>; Complex An electrophotographic photosensitive member 3 was prepared in the same manner as in Example 1 except that the coating solution for charge generation layer having the following composition was used.
-Coating solution composition for charge generation layer-
2 parts of tetrabenzoporphyrin precursor of chemical formula (7)

Polyvinyl butyral 0.1 part (ESREC BM-S, manufactured by Sekisui Chemical Co., Ltd.)
50 parts of tetrahydrofuran

Except that the electrophotographic photosensitive member 3 was used, <Process Cartridge Creation> and <Image Quality Check> were performed in the same manner as in Example 1.
The evaluation results are shown in Table 1.

ポリビニルブチラール ０．１部
（エスレックＢＭ−Ｓ、積水化学工業社製）
テトラヒドロフラン ５０部 [Example 4]
<Preparation of Electrophotographic Photoreceptor 4> Introduction of Substituent An electrophotographic photosensitive member 3 was prepared in the same manner as in Example 1 except that the charge generation layer coating solution having the following composition was used.
-Coating solution composition for charge generation layer-
2 parts of tetrabenzoporphyrin precursor of formula (6)

Polyvinyl butyral 0.1 part (ESREC BM-S, manufactured by Sekisui Chemical Co., Ltd.)
50 parts of tetrahydrofuran

Except that the electrophotographic photosensitive member 4 was used, <Process Cartridge Creation> and <Image Quality Check> were performed in the same manner as in Example 1.
The evaluation results are shown in Table 1.

[Example 5]
<Preparation of Electrophotographic Photoreceptor 5>: Undercoat layer difference An undercoat layer coating solution having the following composition was used, and the thickness of the undercoat layer was adjusted to 3.5 μm. A photoconductor 5 was prepared.
−Coating liquid composition for undercoat layer−
Alkyd resin 6 parts (Beccosol 1307-60-EL, manufactured by Dainippon Ink & Chemicals, Inc.)
Melamine resin 4 parts (Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.)
Titanium oxide 40 parts (CR-EL, manufactured by Ishihara Sangyo Co., Ltd.)
200 parts of methyl ethyl ketone

Except that the electrophotographic photosensitive member 5 was used, <Process Cartridge Creation> and <Image Quality Check> were performed in the same manner as in Example 1.
The evaluation results are shown in Table 1.

[Comparative Example 1]
<Preparation of electrophotographic photoreceptor 6>
The electrophotographic photosensitive member 6 was prepared in the same manner as in Example 1 except that a charge generation layer coating solution having the following composition was used and dried by heating at 120 ° C. for 20 minutes to form a 0.2 μm charge generation layer. Produced.
-Coating solution composition for charge generation layer-
Oxotitanium phthalocyanine pigment 2 parts Polyvinyl butyral 0.2 part (S-REC BM-S, manufactured by Sekisui Chemical Co., Ltd.)
50 parts of tetrahydrofuran

Except that the electrophotographic photosensitive member 6 was used, <Process Cartridge Creation> and <Image Quality Check> were performed in the same manner as in Example 1.
The evaluation results are shown in Table 1.

Next, the comparison results of Examples 1 to 5 and Comparative Example 1 are shown.
<Comparison of Examples 1, 2, 3, 4, 5 and Comparative Example 1>
Examples 1, 2, 3, 4, 5 based on an electrophotographic photosensitive member including a charge generating material having a tetrabenzoporphyrin skeleton, and Comparative Example 1 based on an electrophotographic photosensitive member not including a charge generating material having a tetrabenzoporphyrin skeleton The comparison result will be described. Table 1 shows that evaluation of image quality is improved when an electrophotographic photosensitive member containing a charge generating material having a tetrabenzoporphyrin skeleton is used. When using an electrophotographic photoreceptor that does not contain a charge-generating material having a tetrabenzoporphyrin skeleton, the image quality is not sufficient from the beginning due to the non-uniformity of the charge-generating layer, and the surface of the electrophotographic photoreceptor in a paper passing test. As a result of the damage, the non-uniformity of the charge generation layer appears more remarkably, and the deterioration of the image quality becomes remarkable.
Therefore, the usefulness of the charge generation material having a tetrabenzoporphyrin skeleton was proved.

<Comparison between Examples 1 and 2 and Examples 3 and 4>
As a charge generation material having a tetrabenzoporphyrin skeleton, in Examples 1 and 2, tetrabenzoporphyrin which is not substituted with a characteristic group or complexed with a metal atom is used. In Examples 3 and 4, tetrabenzoporphyrin is used. In any of the examples, sufficient image quality can be obtained even in the initial stage and after the paper passing test, and it is effective for obtaining good image quality. The structure of the charge generation material was confirmed to be in the tetrabenzoporphyrin skeleton.

<Comparison between Example 1 and Example 5>
In Example 1, the electron-accepting material and the N-type semiconductor particles are simultaneously contained in the undercoat layer, whereas in Example 5, neither material is contained in the undercoat layer. Therefore, in Example 5, the uniformity of the solid image portion is slightly deteriorated during the image quality after the paper passing test. This is because charge generation materials having a tetrabenzoporphyrin skeleton generate photocharges very efficiently, so that the surface charge of the electrophotographic photosensitive member is canceled by exposure and the counter charge generated when forming an electrostatic latent image is reduced. This indicates that it is preferable to contain an electron-accepting material and N-type semiconductor particles in the undercoat layer in order to escape to the support more quickly.

  From these results, the electrophotographic photoreceptor has a charge generation layer containing a charge generation material, and the charge generation material contains a compound having a tetrabenzoporphyrin skeleton, a process cartridge using the same, an image The superiority of the image quality of the forming device was shown.

[Example 6]
<Preparation of electrophotographic photoreceptor 7>
As the conductive cylindrical support, an aluminum cylinder having an outer diameter of 40 mm and a wall thickness of 0.8 mm was used. On this aluminum cylinder, an undercoat layer coating solution, a charge generation layer coating solution, and a charge transfer layer coating solution having the following composition are sequentially applied by dip coating and drying to obtain a 15 μm undercoat layer, An electrophotographic photosensitive member 7 was obtained by forming a 0.15 μm charge generation layer lower layer, a 0.1 μm charge generation layer upper layer, and a charge transfer layer of about 30 μm.

酸化チタン １５部
（ＣＲ−ＥＬ、石原産業社製）
メチルエチルケトン ２００部 [Coating liquid for undercoat layer]
An undercoat layer coating solution having the following composition was dip-coated on the aluminum cylinder, and then heated and dried at 120 ° C. for 25 minutes to form a 15 μm undercoat layer.
−Coating liquid composition for undercoat layer−
Alkyd resin 6 parts (Beccosol 1307-60-EL, manufactured by Dainippon Ink & Chemicals, Inc.)
Melamine resin 4 parts (Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.)
N-type semiconductor Aluminum-doped zinc oxide 25 parts (Pazet CK, manufactured by Hakusui Tech Co., Ltd.)
Charge acceptor material Silylmethylfullerene derivative of formula (I) 0.5 part

Titanium oxide 15 parts (CR-EL, manufactured by Ishihara Sangyo Co., Ltd.)
200 parts of methyl ethyl ketone

化学式（Ｉ）のシリルメチルフラーレン誘導体 ０．５部

ポリビニルブチラール ０．０３部
（エスレックＢＭ−Ｓ、積水化学工業社製）
テトラヒドロフラン ５０部 [Coating liquid for charge generation layer 1]
A coating solution for charge generation layer 1 having the following composition is applied onto the undercoat layer by dip coating and then heated and dried at 120 ° C. for 20 minutes to form a 0.15 μm pre-heat conversion charge generation layer 1 (lower layer). did.
-Coating liquid composition for charge generation layer 1-
0.8 parts of tetrabenzoporphyrin precursor of chemical formula (2)

0.5 part of silylmethylfullerene derivative of formula (I)

Polyvinyl butyral 0.03 part (ESREC BM-S, manufactured by Sekisui Chemical Co., Ltd.)
50 parts of tetrahydrofuran

[Coating solution for charge generation layer 2]
After dip-coating the coating solution for charge generation layer 2 having the following composition on the charge generation layer 1 before heat conversion, followed by heating and drying at 120 ° C. for 20 minutes up to 140 ° C. at a temperature rising rate of 5 ° C. per minute. The temperature is raised and held for 10 minutes as it is, and further heated to 180 ° C. at a heating rate of 5 ° C. per minute, and kept for 15 minutes as it is, to the tetrabenzoporphyrin precursor of tetrabenzoporphyrin. The heat generation and the formation of the PN junction were performed to form a total charge generation layer of 0.25 μm.

ポリビニルブチラール ０．０３部
（エスレックＢＭ−Ｓ、積水化学工業社製）
テトラヒドロフラン ５０部 -Coating liquid composition for charge generation layer 2-
2 parts of tetrabenzoporphyrin precursor of formula (5)

Polyvinyl butyral 0.03 part (ESREC BM-S, manufactured by Sekisui Chemical Co., Ltd.)
50 parts of tetrahydrofuran

[Coating liquid for charge transfer layer]
A charge transfer layer coating solution having the following composition was dip-coated on the charge generation layer, and then heated and dried at 135 ° C. for 20 minutes to form a charge transfer layer. In the dip coating process, the lifting speed and the surrounding atmosphere were adjusted so that the amount of coating liquid deposited was uniform.

ビスフェノールＺポリカーボネート １０部
（パンライトＴＳ−２０５０：帝人化成社製）
シリコーンオイル ０．００２部
（ＫＦ−５０、信越化学工業社製）
テトラヒドロフラン １００部 -Coating liquid composition for charge transfer layer-
10 parts of charge transfer material (D-1) represented by the following structural formula

Bisphenol Z polycarbonate 10 parts (Panlite TS-2050: manufactured by Teijin Chemicals Ltd.)
0.002 part of silicone oil (KF-50, manufactured by Shin-Etsu Chemical Co., Ltd.)
Tetrahydrofuran 100 parts

The coating layer thickness of the obtained electrophotographic photoreceptor 7 was 45.3 μm on average.
The electrophotographic photoreceptor 7 was provided with flanges at both ends.

<Production of process cartridge>
The flanged electrophotographic photosensitive member 1 was incorporated in an imaging unit of Rigoh's imgio MP C4500. The cartridge used was black.

<Confirmation of image quality>
The prepared process cartridge was replaced with a black cartridge made by Ricoh, imagio MP C4500, and image evaluation was performed according to the above procedure. However, the laser output of the main body was adjusted to 75% of the initial setting value in order to confirm the high sensitivity of the photoconductor.
The evaluation results are shown in Table 2.

[Example 7]
<Preparation of electrophotographic photoreceptor 8>
As a charge generation layer coating solution, a coating solution having the following composition -coating solution composition for charge generation layer 3- was applied by dip coating on the charge generation layer 1 before heat conversion, and then at 120 ° C. for 20 minutes. After heating and drying, the temperature was raised to 160 ° C. at a rate of 5 ° C. per minute, held there for another 10 minutes, and further heated to 180 ° C. at a rate of 5 ° C. per minute. By holding for an additional 15 minutes, heat conversion of the tetrabenzoporphyrin precursor to tetrabenzoporphyrin and formation of the PN junction were performed, and the same procedure as in Example 6 was performed except that a charge generation layer having a total of 0.25 μm was formed. Thus, an electrophotographic photosensitive member 8 was produced.

ポリビニルブチラール ０．０３部
（エスレックＢＭ−Ｓ、積水化学工業社製）
テトラヒドロフラン ５０部 -Coating liquid composition for charge generation layer 3-
2 parts of tetrabenzoporphyrin precursor of formula (4)

Polyvinyl butyral 0.03 part (ESREC BM-S, manufactured by Sekisui Chemical Co., Ltd.)
50 parts of tetrahydrofuran

Except that the electrophotographic photosensitive member 8 was used, <process cartridge creation> and <image quality check> were performed in the same manner as in Example 6.
The evaluation results are shown in Table 2.

酸化チタン １５部
（ＣＲ−ＥＬ、石原産業社製）
メチルエチルケトン ２００部 [Example 8]
<Preparation of electrophotographic photoreceptor 9>
An electrophotographic photoreceptor 9 was produced in the same manner as in Example 6 except that the undercoat layer coating solution having the following composition was used.
−Coating liquid composition for undercoat layer−
Alkyd resin 6 parts (Beccosol 1307-60-EL, manufactured by Dainippon Ink & Chemicals, Inc.)
Melamine resin 4 parts (Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.)
N-type semiconductor Aluminum-doped zinc oxide 25 parts (Pazet CK, manufactured by Hakusui Tech Co., Ltd.)
Charge acceptor material Silylmethylfullerene derivative of formula (II) 0.5 part

Titanium oxide 15 parts (CR-EL, manufactured by Ishihara Sangyo Co., Ltd.)
200 parts of methyl ethyl ketone

Except that the electrophotographic photosensitive member 9 was used, <process cartridge creation> and <image quality check> were performed in the same manner as in Example 6.
The evaluation results are shown in Table 2.

酸化チタン １５部
（ＣＲ−ＥＬ、石原産業社製）
メチルエチルケトン ２００部 [Example 9]
<Preparation of electrophotographic photoreceptor 10>
An electrophotographic photoreceptor 10 was produced in the same manner as in Example 6 except that the undercoat layer coating solution having the following composition was used.
−Coating liquid composition for undercoat layer−
Alkyd resin 6 parts (Beccosol 1307-60-EL, manufactured by Dainippon Ink & Chemicals, Inc.)
Melamine resin 4 parts (Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.)
N-type semiconductor Aluminum-doped zinc oxide 25 parts (Pazet CK, manufactured by Hakusui Tech Co., Ltd.)
Charge acceptance material Fullerene derivative of chemical formula (V) 0.5 part

Titanium oxide 15 parts (CR-EL, manufactured by Ishihara Sangyo Co., Ltd.)
200 parts of methyl ethyl ketone

Except that the electrophotographic photoreceptor 10 was used, <Process Cartridge Creation> and <Image Quality Check> were performed in the same manner as in Example 6.
The evaluation results are shown in Table 2.

[Example 10]
<Preparation of electrophotographic photoreceptor 11>
An electrophotographic photoreceptor 11 was produced in the same manner as in Example 6 except that the undercoat layer coating solution having the following composition was used.
−Coating liquid composition for undercoat layer−
Alkyd resin 6 parts (Beccosol 1307-60-EL, manufactured by Dainippon Ink & Chemicals, Inc.)
Melamine resin 4 parts (Super Becamine G-821-60, manufactured by Dainippon Ink & Chemicals, Inc.)
N-type semiconductor Aluminum-doped zinc oxide 25 parts (Pazet CK, manufactured by Hakusui Tech Co., Ltd.)
Charge accepting material 1,2-dihydroxy-9,10-anthraquinone 0.4 part Titanium oxide 15 parts (CR-EL, manufactured by Ishihara Sangyo Co., Ltd.)
200 parts of methyl ethyl ketone

Except that the electrophotographic photosensitive member 11 was used, <Process Cartridge Creation> and <Image Quality Check> were performed in the same manner as in Example 6.
The evaluation results are shown in Table 2.

[Example 11]
<Preparation of electrophotographic photoreceptor 12>
As the charge generation layer coating solution, only the charge generation layer 1 coating solution of Example 6 was used, and this was dip coated on the undercoat layer, followed by heating and drying at 120 ° C. for 20 minutes. The temperature was raised to 180 ° C. at a temperature rising rate of 5 ° C. and held for 15 minutes as it was, thereby performing the thermal conversion of the tetrabenzoporphyrin precursor to tetrabenzoporphyrin and the formation of the PN junction, 0.25 μm The electrophotographic photosensitive member 12 was produced in the same manner as in Example 6 except that the charge generation layer was formed.

Except that the electrophotographic photosensitive member 12 was used, <Process Cartridge Creation> and <Image Quality Check> were performed in the same manner as in Example 6.
The evaluation results are shown in Table 2.

[Example 12]
<Preparation of electrophotographic photoreceptor 13>
As the charge generation layer coating solution, a charge generation layer coating solution having the following composition was used. After dip-coating the coating layer on the undercoating layer, heating and drying at 120 ° C. for 20 minutes followed by 5 ° C. per minute. The temperature was raised to 180 ° C. at the rate of temperature rise and maintained for 15 minutes as it was, thereby converting the tetrabenzoporphyrin precursor to tetrabenzoporphyrin and forming a 0.25 μm charge generation layer. In the same manner as in Example 6, an electrophotographic photoreceptor 13 was produced.

ポリビニルブチラール ０．１部
（エスレックＢＭ−Ｓ、積水化学工業社製）
テトラヒドロフラン ５０部 -Coating solution composition for charge generation layer-
2 parts of tetrabenzoporphyrin precursor of formula (2)

Polyvinyl butyral 0.1 part (ESREC BM-S, manufactured by Sekisui Chemical Co., Ltd.)
50 parts of tetrahydrofuran

Except that the electrophotographic photosensitive member 13 was used, <Process Cartridge Creation> and <Image Quality Check> were performed in the same manner as in Example 6.
The evaluation results are shown in Table 2.
The electrophotographic photosensitive member 13 was also evaluated in the same manner as in Example 1 with <Process Cartridge Creation> and <Image Quality Check>.
The evaluation results are shown in Table 3.

[Comparative Example 2]
<Preparation of electrophotographic photoreceptor 14>
The electrophotographic photoreceptor 14 was prepared in the same manner as in Example 6 except that a charge generation layer coating solution having the following composition was used and dried by heating at 120 ° C. for 20 minutes to form a 0.25 μm charge generation layer. Produced.

ポリビニルブチラール ０．２部
（エスレックＢＭ−Ｓ、積水化学工業（株）製）
テトラヒドロフラン ５０部 -Coating solution composition for charge generation layer-
Oxotitanium phthalocyanine pigment 2 parts Silylmethylfullerene derivative of formula (I) 0.5 parts

Polyvinyl butyral 0.2 part (S REC BM-S, manufactured by Sekisui Chemical Co., Ltd.)
50 parts of tetrahydrofuran

Except that the electrophotographic photosensitive member 14 was used, <Process Cartridge Creation> and <Image Quality Check> were performed in the same manner as in Example 6.
The evaluation results are shown in Table 2.
The electrophotographic photosensitive member 14 was also evaluated in the same manner as in Example 1 by performing <Process Cartridge Creation> and <Confirming Image Quality>.
The evaluation results are shown in Table 3.

Next, the comparison results of Examples 6 to 12 and Comparative Example 2 are shown.
<Comparison of Examples 6, 7, 8, 9, 10, 11 and Example 12, Comparative Example 2>
Charges comprising only the compounds having Examples 6, 7, 8, 9, 10, and 11 having a tetrabenzoporphyrin skeleton, and electrophotographic photoreceptors including a charge generating material comprising a compound having a tetrabenzoporphyrin skeleton and a silylmethylfullerene derivative, The results of comparison with Example 12 using an electrophotographic photoreceptor containing a generating material and Comparative Example 2 using an electrophotographic photoreceptor containing a charge generating material composed of a compound having no tetrabenzoporphyrin skeleton and a silylmethylfullerene derivative will be described.
Table 2 shows that evaluation of image quality is improved when an electrophotographic photosensitive member containing a charge generation material composed of a compound having a tetrabenzoporphyrin skeleton and a silylmethylfullerene derivative is used. In the case of using an electrophotographic photosensitive member made of a charge generating material consisting only of a compound having a tetrabenzoporphyrin skeleton, when the light energy applied at the time of exposure is reduced, the generation of photocharge becomes insufficient, and the image from the beginning The quality is not sufficient, and the electrophotographic photosensitive member is damaged due to charge accumulation in the paper passing test. As a result, the nonuniformity of the charge generation becomes more noticeable, and the deterioration of the image quality becomes remarkable. .
However, when the exposure energy applied at the time of exposure is normal exposure energy as shown in Table 3, the electrophotographic photosensitive member of Example 12 including a charge generation material composed only of a compound having a tetrabenzoporphyrin skeleton is also sufficient. It can be seen that image quality can be obtained. The electrophotographic photosensitive member of Comparative Example 3 does not contain a compound having a tetrabenzoporphyrin skeleton because the charge generation layer does not contain a compound having a tetrabenzoporphyrin skeleton even when the exposure energy applied during exposure is normal exposure energy. In the same manner as above, a defect that is considered to be caused by non-uniformity of the charge generation material dispersion occurred. As for the visual solid of the initial quality, since it contains the silylmethylfullerene derivative represented by the chemical formula (I), the result is somewhat better than Comparative Example 1, but the quality could not be maintained. .
Therefore, the usefulness of the electrophotographic photoreceptor including a charge generation material comprising a compound having a tetrabenzoporphyrin skeleton and a silylmethylfullerene derivative has been proved.

<Comparison between Examples 6 and 7 and Example 8>
As an electron accepting material for the undercoat layer, in Examples 6 and 7, a silylmethylfullerene derivative having a specific structure (chemical formula (I)) is used, whereas in Example 8, other silylmethylfullerene derivatives are used. Is used. When silylmethylfullerene derivatives other than the specific structure were used, a slight change appeared in the solid image area after the paper passing test. Thereby, it was confirmed that the structure of the compound (I) is effective for the electrophotographic photoreceptor among the silylmethylfullerene derivatives.

<Comparison of Examples 6, 7, 8 and Example 9>
As the electron-accepting material for the undercoat layer, silylmethylfullerene derivatives are used in Examples 6, 7, and 8, while other fullerene derivatives are used in Example 9. When fullerene derivatives other than the silylmethyl fullerene derivative were used, a slight change appeared in the solid image portion and the 2by2 halftone portion after the paper passing test. As a result, it was confirmed that among the fullerene derivatives, the silylmethylfullerene derivative is effective for the electrophotographic photoreceptor.

<Comparison of Examples 6, 7, 8, 9 and Example 10>
As the electron accepting material for the undercoat layer, fullerene derivatives are used in Examples 6, 7, 8, and 9, whereas in Example 10, 1,2-dihydroxy-9, 10-anthraquinone is used. When an electron-accepting material other than the fullerene derivative was used, deterioration appeared in the solid image portion and the 2by2 halftone portion after the paper passing test. Thereby, it was confirmed that the fullerene derivative is effective for the electrophotographic photoreceptor among the electron-accepting materials.

<Comparison between Examples 6 and 7 and Example 11>
In Examples 6 and 7, the charge generation layer has a two-layer structure of a lower layer made of a compound having a tetrabenzoporphyrin skeleton and a silylmethylfullerene derivative and an upper layer made of a compound having a tetrabenzoporphyrin skeleton. In Example 11, one charge generation layer made of a compound having a tetrabenzoporphyrin skeleton and a silylmethylfullerene derivative is used. In the case of a single charge generation layer, a slight change appeared in the solid image portion, the blank image portion, and the 2by2 halftone portion after the paper passing test. Thereby, the charge generation layer contains, from the side close to the conductive support, a layer containing at least a compound having a tetrabenzoporphyrin skeleton and a silylmethylfullerene compound, and at least a compound having a tetrabenzoporphyrin skeleton. It was confirmed that it was effective for the electrophotographic photoreceptor to form a layer containing no silylmethylfullerene compound in this order.

  From these results, the electrophotographic photosensitive layer has a layer containing a charge generating material, and the charge generating material contains an electrophotographic photosensitive member containing a compound having a tetrabenzoporphyrin skeleton and a silylmethylfullerene compound. The superiority of the image quality of the existing process cartridge and image forming apparatus was shown.

1Y, C, M, K Electrophotographic photosensitive member 2 Charging device 3 Writing device 4 Developing device 5 Intermediate transfer belt 6 Cleaning device 7 Fixing device 8 Paper discharge tray 9 Light guide member 10 Electrophotographic photosensitive member support 11 Undercoat layer 12 Photosensitive layer 20 Charging roller 21 Charging cleaning roller 40 Developing sleeve 41 Developer stirring and conveying member 42 Developer stirring and conveying member 50 Intermediate transfer belt supporting roller 51 Intermediate transfer belt supporting roller 52Y, C, M, K Primary transfer roller 53 Secondary Transfer roller 60 Cleaning blade 100 Image forming apparatus 120 Charge generation layer 1200 Charge generation layer lower layer (containing silylmethylfullerene derivative)
1201 Upper layer of charge generation layer (not containing silylmethylfullerene derivative)
121 charge transfer layer 200 paper feed mechanism 300 process cartridge

JP-A-8-311363 Japanese Patent Laid-Open No. 9-311477 JP-A-10-55074 Japanese Patent Laid-Open No. 11-15179 JP-A-4-184449 JP 2002-131944 A

Claims (10)

  Electrons obtained by forming at least an undercoat layer, a charge generation layer containing a charge generation material, and a charge transfer layer containing a charge transfer material in this order on at least a conductive support from the side close to the conductive support. An electrophotographic photoreceptor, wherein the charge generating material contains a compound having a tetrabenzoporphyrin skeleton.   The electrophotographic photosensitive member according to claim 1, wherein the charge generation layer contains a silylmethylfullerene compound.   The charge generation layer contains, from the side close to the conductive support, a layer containing at least a compound having a tetrabenzoporphyrin skeleton and a silylmethylfullerene compound, and at least a compound having a tetrabenzoporphyrin skeleton containing silylmethyl The electrophotographic photosensitive member according to claim 1, wherein a layer not containing a fullerene compound is formed in this order.   The electrophotographic photoreceptor according to claim 1, wherein the undercoat layer contains at least an electron-accepting material and N-type semiconductor particles.   The electrophotographic photosensitive member according to claim 4, wherein the electron-accepting material is a fullerene derivative.   The electrophotographic photosensitive member according to claim 5, wherein the fullerene derivative is a silylmethylfullerene compound. The electrophotographic photosensitive member according to any one of claims 2 to 6, wherein the silylmethylfullerene compound is a compound represented by the following chemical formula (I).

  A process cartridge having at least an electrophotographic photosensitive member, a charging unit that charges the electrophotographic photosensitive member, and a cleaning unit that cleans residual toner on the electrophotographic photosensitive member. A process cartridge which is the electrophotographic photosensitive member according to any one of the above.   At least the electrophotographic photosensitive member, charging means for charging the electrophotographic photosensitive member, writing means for forming an electrostatic latent image on the electrophotographic photosensitive member, and the electrostatic latent image are visualized with toner. Developing means; transfer means for transferring the toner visible image on the electrophotographic photosensitive member onto the recording medium with or without the intermediate transfer medium; and fixing means for fixing and fixing the toner image on the recording medium; An image forming apparatus comprising: the electrophotographic photosensitive member according to claim 1, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to claim 1.   At least a process cartridge, writing means for forming an electrostatic latent image on the electrophotographic photosensitive member, developing means for visualizing the electrostatic latent image with toner, and a toner visible image on the electrophotographic photosensitive member In an image forming apparatus having a transfer unit that transfers the toner image onto a recording medium with or without an intermediate transfer medium, and a fixing unit that fixes and fixes a toner image on the recording medium, the process cartridge includes: An image forming apparatus, which is the process cartridge according to claim 8.

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