JP5277764B2 - Electrophotographic photoreceptor, image forming apparatus using the same, and process cartridge - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electrophotographic photoreceptor capable of achieving image formation at higher speed while reducing an initial residual potential in an electrophotographic photoreceptor having a surface protective layer as an outermost surface layer containing filler, suppressing image degradation by image blur and increase in a residual potential, and stably forming images of high image quality even in repeated use for a long period of time, and to provide an image forming apparatus and a process cartridge using the above electrophotographic photoreceptor. <P>SOLUTION: The photoreceptor includes a support, and at least a photosensitive layer and a surface protective layer on the support, wherein the surface protective layer contains filler, a charge transporting material and a predetermined compound, the photosensitive layer contains at least a charge transporting material, and the charge transporting material in the photosensitive layer has a lower oxidation potential than the charge transporting material in the surface protective layer, and the photosensitive layer contains a predetermined compound. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to an electrophotographic photoreceptor used for electrophotographic image formation such as a copying machine, electrostatic printing, printer, facsimile, electrostatic recording, and the like, an image forming apparatus using the same, and a process cartridge.

  In recent years, there has been a remarkable development in information processing system machines based on electrophotography. In particular, laser printers and digital copying machines that record information using light after converting information into digital signals are significantly improved in print quality and reliability. These have been applied to laser printers and digital copiers capable of full-color printing by merging with high-speed technology. From such a background, it is particularly important to achieve both high image quality and high durability as a required function of an electrophotographic photosensitive member (hereinafter also referred to as “photosensitive member”). Yes.

  As photoconductors used in such electrophotographic laser printers and digital copiers, organic photoconductors (OPCs) using organic photosensitive materials are cost, productivity and pollution-free. It is generally used widely for the reason. As the organic photoconductor (OPC), for example, (1) a photoconductive resin represented by polyvinylcarbazole (PVK), (2) PVK-TNF (2,4,7-tri A charge transfer complex type represented by (nitrofluorenone), (3) a pigment dispersion type represented by phthalocyanine-binder, and (4) a charge generation layer containing a charge generation material and a charge transport layer containing a charge transport material. Combined function separation type, etc.

However, the organic photoreceptor (OPC) is prone to scraping of the photosensitive layer due to repeated use, and as the shaving of the photosensitive layer proceeds, the charged potential of the photoreceptor decreases, the photosensitivity deteriorates, The tendency to promote background contamination, image density reduction, or image quality deterioration due to scratches on the surface of the body has become stronger, and conventionally, the abrasion resistance of the photoreceptor has been a major issue. Further, in recent years, with the increase in the speed of the image forming apparatus and the reduction in the diameter of the photosensitive body accompanying the downsizing of the apparatus, it has become an even more important issue to improve the durability of the photosensitive body.
As a method for realizing such high durability of the photoconductor, for example, a method is provided in which a surface protective layer is provided on the outermost surface of the photoconductor, and the surface protective layer is lubricated, cured, or contains a filler. Etc. are done. Among these, the method of incorporating a filler in the surface protective layer is one of the effective methods for enhancing the durability of the photoreceptor (for example, Patent Document 1, Patent Document 2, Patent Document 3, Patent Document 4, (See Patent Literature 5 and Patent Literature 6).

However, when a filler is contained in the surface protective layer for high durability, the resistance increases and the residual potential is remarkably increased. This increase in the residual potential is greatly affected by the increase in resistance and the increase in charge trap sites caused by the inclusion of the filler. On the other hand, when the conductive filler is used, the resistance decreases and the effect of the increase in the residual potential is relatively small, but the so-called image blurring that blurs the outline of the image occurs, and the effect on the image quality appears strongly. .
When the photosensitive layer is prevented from being scraped by a method of containing a filler in the surface protective layer, ozone, NOx, or other oxidizing substances generated by repeated use or the surrounding environment are adsorbed on the surface of the surface protective layer, and are repeatedly used or used. It is known that depending on the environment, the resistance of the surface protective layer is lowered, causing problems such as image flow (image blur).
Conventionally, the problem has been avoided to some extent by removing the blurring material together with the surface protective layer. However, in order to meet the recent demand for higher resolution and higher durability, it has become necessary to provide a new method. Additives such as antioxidants are also effective means, but mere additives do not have photoconductivity, so adding a large amount of filler to the surface protective layer can reduce sensitivity, increase residual potential, etc. This leads to problems with electrophotographic characteristics.

A higher surface resistance of the photoconductor is suitable for suppressing the occurrence of image blur. On the other hand, the surface and film itself are used for reducing the initial residual potential of the photoconductor and suppressing the increase of the residual potential during repeated use. Since the lower resistance is more suitable, the trade-off relationship between the two makes it difficult to solve the problem.
The increase in residual potential, which is often seen when using a highly insulating filler, leads to a high bright portion potential in an electrophotographic image forming apparatus, leading to a decrease in image density and gradation. . In order to compensate for this, it is necessary to increase the dark part potential. However, if the dark part potential is increased, the electric field strength is increased, which not only causes image defects such as background stains, but also reduces the life of the photoreceptor. Connected.
For this reason, fillers with high insulating properties are difficult to use, and fillers with low insulating properties that are relatively less affected by residual potential are used, and drum heaters that heat the photoreceptor are mounted against image blur caused by the fillers. Means are used. Although the occurrence of image blur can be suppressed by heating the photoreceptor, this method is a major obstacle to downsizing the image forming apparatus, reducing power consumption, and shortening the startup time of the apparatus.

  In recent years, color image forming apparatuses using roller charging method charging means that can save energy, generate less ozone, and become more compact have become mainstream. Therefore, the charging means of the non-contact corona discharge method that has been conventionally used has been reviewed. However, the corona discharge charging means generates a larger amount of discharge products (ozone, NOx, etc.) due to discharge than the roller charging method, and uses a photoreceptor containing a filler on the outermost layer for higher durability. Then, image blurring is more likely to occur.

  Also, in order to improve the image quality, a lubricant is added to the electrophotographic photosensitive member for the purpose of improving the transfer rate, reducing the void in the characters and uneven transfer of the solid image, and further improving the cleaning property by the cleaning blade. There has been proposed an image forming apparatus provided with a lubricant applying means for applying and lowering a friction coefficient. In the image forming apparatus provided with such a lubricant applying means, as another advantage, the wear amount of the photoconductor and the photoconductor filming are reduced, and the life of the photoconductor can be extended. Furthermore, when combined with a photoconductor containing a filler in the surface protective layer in order to achieve high durability, it is resistant to photoconductor abrasion and photoconductor surface scratches due to variations in the amount of lubricant applied by the lubricant applying means. Therefore, the durability can be further enhanced as compared with a photoreceptor that does not contain a filler in the surface protective layer. The problem has been avoided to some extent by causing the blurring material that causes image blurring to be removed together with the surface protective layer. However, in such an image forming process in which the photoconductor is hard to be scraped, in order to further improve durability, resistance to image blur and stability of electrostatic characteristics other than photoconductor wear (reduction in increase in residual electric power) are required. Yes.

  As described above, when a filler is contained in the outermost surface protective layer for high durability, there are no effective means for simultaneously solving the reduction of the initial residual potential, the increase of the residual potential due to repeated use, and the image blur. In fact, in a higher-speed image forming apparatus, there are still problems regarding high durability and high image quality.

JP-A-53-133444 Japanese Patent Laid-Open No. 55-157748 Japanese Unexamined Patent Publication No. 57-30846 JP-A-2-4275 JP-A-4-281461 JP 2000-66434 A

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention can reduce the initial residual potential in an electrophotographic photosensitive member containing a filler in the surface protective layer, which is the outermost surface layer, to realize higher-speed image formation, and image degradation and residual potential due to image blurring. To provide an electrophotographic photosensitive member capable of stably forming a high-quality image even when used repeatedly for a long period of time, an image forming apparatus using the electrophotographic photosensitive member, and a process cartridge. With the goal.

  In order to solve the above-mentioned problems, the present inventors reduced the initial residual potential for an electrophotographic photosensitive member containing a filler in the surface protective layer on the outermost surface in order to achieve high durability, and caused image degradation and residual potential due to image blurring. As a result of intensive studies to solve the increase, a charge transport material having a low oxidation potential is contained in the photosensitive layer, and a charge transport material having a higher oxidation potential than the charge transport material contained in the photosensitive layer is contained in the surface protective layer. In general, it was thought that the difference in the oxidation potential of the charge transport materials contained in both layers would become a charge injection barrier, resulting in a decrease in charge transport efficiency and a large increase in residual potential. Even if the surface protective layer is configured, if the surface protective layer is not thick, the increase in residual potential can be suppressed, and high-quality images can be stably and rapidly formed even after repeated use over a long period of time. It was seen.

The present invention is based on the above findings by the present inventors, and means for solving the above problems are as follows. That is,
<1> An electrophotographic photosensitive member having a support and at least a photosensitive layer and a surface protective layer on the support,
The surface protective layer contains a filler, a charge transport material, and a compound represented by any one of the following general formulas (1) and (2),
The photosensitive layer contains at least a charge transporting substance, the charge transporting substance in the photosensitive layer has an oxidation potential smaller than that of the charge transporting substance in the surface protective layer, and is represented by the following general formula (3) An electrophotographic photosensitive member characterized by the above.
However, in the general formula (1), R ¹ and R ² may be the same as or different from each other, and may have an alkyl group which may have a substituent, and a substituent. Any one of the aryl groups which may be present, and at least one of R ¹ and R ^{2 is} an aryl group which may have a substituent. R ¹ and R ² may be bonded to each other to form a heterocyclic ring containing a nitrogen atom, and the heterocyclic ring may be further substituted with a substituent. Ar represents an arylene group which may have a substituent.
However, in the general formula (2), R ¹ and R ² may be the same as or different from each other, and may have an alkyl group which may have a substituent, and a substituent. Any of the aryl groups that may be present, and R ¹ and R ² may be bonded to each other to form a heterocyclic ring containing a nitrogen atom, and the heterocyclic ring is further substituted with a substituent; Also good. Ar ¹ and Ar ² each represent an arylene group which may have a substituent. l and m each represent an integer of 0 to 3, and l and m are not 0 at the same time. n represents an integer of 1 or 2.
However, in said general formula (3), R < ³ > -R < ⁶ > is the phenyl which may have a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, and a substituent, respectively. Represents any of the groups.
A represents an arylene group which may have a substituent and a substituent represented by the following structural formula (3-1).
However, in said structural formula (3-1), R < ⁷ >, R < ⁸ > and R < ⁹ > are either a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, and a phenyl group. And the phenyl group may be further substituted with a substituent.
B represents any of an aryl group which may have a substituent and a substituent represented by the following structural formula (3-2).
However, in the structural formula (3-2), Ar ³ represents an arylene group which may have a substituent. Ar ⁴ and Ar ⁵ each represents an aryl group which may have a substituent.
<2> The electrophotographic photosensitive member according to <1>, wherein the charge transport material in the photosensitive layer is a distyrylbenzene derivative represented by the following general formula (4).
However, in said general formula (4), R < ¹⁰ > -R < ³⁵ > may mutually be the same and may differ, A hydrogen atom, a C1-C4 alkyl group, C1-C4 It represents either an alkoxy group or a phenyl group which may have a substituent.
<3> The electrophotographic photosensitive member according to any one of <1> to <2>, wherein the photosensitive layer contains a charge generating substance, and the charge generating substance contains a titanyl phthalocyanine pigment.
<4> A diffraction peak having a maximum intensity at 27.2 ° of the black angle (2θ ± 0.2 °) in an X-ray diffraction spectrum using a CuKα characteristic X-ray (1.542 °) when the titanyl phthalocyanine pigment is used. Having a main peak at 9.4 °, 9.6 °, and 24.0 °, a diffraction peak with a minimum angle at 7.3 °, and 7.3 ° and 9.4 ° The electrophotographic photosensitive member according to <3>, which does not have a diffraction peak in between and has no diffraction peak at 26.3 °.
<5> Any one of <1> to <4>, wherein a difference between an oxidation potential of the charge transport material in the surface protective layer and an oxidation potential of the charge transport material in the photosensitive layer is 0.01 V to 0.20 V. This is an electrophotographic photoreceptor.
<6> The electrophotographic photosensitive member according to any one of <1> to <5>, wherein the melting point of the charge transport material in the surface protective layer is 170 ° C. or lower.
<7> The electrophotographic photosensitive member according to any one of <1> to <6>, wherein the content of the charge transport material in the photosensitive layer is 65 masses or more with respect to 100 parts by mass of the resin contained in the photosensitive layer. is there.
<8> The photosensitive layer contains an additive having a melting point of 150 ° C. or less, and the content of the additive is 2.5 parts by mass to 10 parts by mass with respect to 100 parts by mass of the charge transport material in the photosensitive layer. <1> to the electrophotographic photoreceptor according to any one of <7>.
<9> The electrophotographic photosensitive member according to <8>, wherein the additive in the photosensitive layer is at least one compound represented by the following structural formulas (1) to (3).
<10> The electron according to any one of <2> to <9>, wherein the charge transport material represented by any one of the general formulas (3) and (4) in the photosensitive layer has a melting point of 170 ° C to 240 ° C. It is a photographic photoreceptor.
<11> The electrophotographic photosensitive member according to any one of <1> to <10>, wherein the filler contains at least one selected from metal oxides.
<12> The electrophotographic photosensitive member according to any one of <1> to <11>, wherein the filler has an average primary particle size of 0.01 μm to 1.0 μm.
<13> The electrophotographic photosensitive member according to any one of <1> to <12>, wherein a content of the filler in the surface protective layer is 5% by mass to 50% by mass.
<14> The electrophotographic photosensitive member according to any one of <1> to <13>, wherein the surface protective layer contains an organic compound having an acid value of 10 mgKOH / g to 700 mgKOH / g.
<15> The electrophotographic photosensitive member according to any one of <1> to <14>, wherein the surface protective layer has a thickness of 0.1 μm to 10 μm.
<16> The photosensitive layer has a charge generation layer and a charge transport layer, and the charge transport layer contains the charge transport material represented by any one of the general formulas (3) and (4). To <15>.
<17> An electrophotographic photosensitive member, charging means for charging the surface of the electrophotographic photosensitive member, exposure means for exposing the charged electrophotographic photosensitive member surface to form an electrostatic latent image, and the electrostatic latent image At least development means for developing a visible image by using toner, transfer means for transferring the visible image to a recording medium, and fixing means for fixing the transfer image transferred to the recording medium An image forming apparatus,
An electrophotographic photosensitive member according to any one of <1> to <16>, wherein the electrophotographic photosensitive member is an image forming apparatus.
<18> The exposure means is any one of a semiconductor laser (LD) and a light emitting diode (LED), and the electrostatic latent image is written on the electrophotographic photosensitive member by digital using the exposure means <17 > Is an image forming apparatus.
<19> The image forming apparatus according to <17>, wherein the exposure unit employs a multi-beam exposure method in which a plurality of beam bundles are used to simultaneously expose a plurality of exposure regions.
<20> The image forming apparatus according to <19>, wherein the light source employed in the multi-beam exposure method is configured by four or more surface-emitting laser arrays.
<21> The light source employed in the multi-beam exposure method includes four or more surface-emitting laser arrays, and the surface-emitting lasers are two-dimensionally arranged. The image forming apparatus described.
<22> The image forming apparatus according to any one of <17> to <21>, wherein a color image is formed by sequentially superimposing a plurality of colors of visible images on an electrophotographic photosensitive member.
<23> Any one of the items <17> to <22>, which has a plurality of electrophotographic photosensitive members and forms a color image by sequentially superimposing single-color visible images developed on the respective electrophotographic photosensitive members. The image forming apparatus described in the above.
<24> An intermediate transfer unit that primarily transfers a visible image developed on an electrophotographic photosensitive member onto an intermediate transfer member and then secondary-transfers the visible image on the intermediate transfer member onto a recording medium. Any one of <17> to <23>, wherein a plurality of colors of visible images are sequentially superimposed on the intermediate transfer member to form a color image, and the color image is secondarily transferred onto the recording medium at once. The image forming apparatus described.
<25> The image forming apparatus according to any one of <17> to <24>, wherein the charging unit is a corona charging unit that discharges in a non-contact manner.
<26> A process cartridge having at least one means selected from a charging means, an exposure means, a developing means, a transfer means, a cleaning means, and a charge eliminating means, and an electrophotographic photosensitive member, and is detachable from the image forming apparatus main body The process cartridge is characterized in that the electrophotographic photoreceptor is the electrophotographic photoreceptor according to any one of <1> to <16>.
<27> A charging step for charging the surface of the electrophotographic photosensitive member, an exposure step for exposing the charged electrophotographic photosensitive member surface to form an electrostatic latent image, and developing the electrostatic latent image with toner. An image forming method comprising at least a development step for forming a visible image, a transfer step for transferring the visible image to a recording medium, and a fixing step for fixing the transfer image transferred to the recording medium,
An image forming method using the electrophotographic photoreceptor according to any one of <1> to <16> as the electrophotographic photoreceptor.

The electrophotographic photosensitive member of the present invention comprises a support, and at least a photosensitive layer and a surface protective layer on the support.
The surface protective layer contains a filler, a charge transport material, and a compound represented by any one of the general formulas (1) and (2),
The photosensitive layer contains at least a charge transport material, the charge transport material in the photosensitive layer has an oxidation potential smaller than that of the charge transport material in the surface protective layer, and is represented by the general formula (3) Preferably, it is a compound represented by the general formula (4).

Conventionally, in order to reduce the initial residual potential, the hole mobility represented by any one of the general formulas (3) and (4) disclosed in Japanese Patent No. 2552695 is high, and the oxidation potential is low. Inclusion of a charge transport material in the photosensitive layer and surface protective layer is effective in reducing the initial residual potential and suppressing the increase in residual potential due to repeated use, but ozone, NOx, or other oxidation caused by repeated use and the surrounding environment There is a problem that image blur due to the active substance occurs remarkably, and image blur tends to occur as the oxidation potential of the charge transport material contained in the surface protective layer decreases.
Therefore, even if the photosensitive layer contains the charge transport material represented by any one of the general formulas (3) and (4), the surface protective layer is higher than the charge transport material contained in the photosensitive layer. By containing a charge transporting substance having an oxidation potential and containing the compound represented by any one of the general formulas (1) and (2) in the surface protective layer, image blurring is suppressed, and residual potential due to repeated use The rise can be suppressed at the same time. That is, for a photoreceptor containing a filler in a surface protective layer for high durability, the surface protective layer contains a charge transport material and a compound represented by any one of the general formulas (1) and (2), A charge transport material having an oxidation potential smaller than that of the charge transport material contained in the protective layer and containing the charge transport material represented by any one of the general formulas (3) and (4) is contained in the photosensitive layer. Thus, it has been found that the initial residual potential can be reduced, and image degradation and residual potential increase due to image blur can be solved.

  In order to achieve high durability of the electrophotographic photosensitive member, it is effective to provide a surface protective layer containing a filler as the outermost surface layer on a conventional photosensitive member. However, as described above, there is a problem that image quality deterioration such as an increase in residual potential and occurrence of image blurring occurs. Even in the case of an image forming apparatus in which an electrophotographic photosensitive member containing a filler in the surface protective layer for such a long life and a corona discharge type charging means for discharging in a non-contact manner is combined, the best of the photosensitive member. An oxidizing gas generated by the surrounding environment containing the compound of any one of the general formulas (1) and (2) as disclosed in JP-A-2004-233955 and JP-A-2004-264788 in the surface layer In addition, it has been found that by providing resistance not only to substances but also to oxidizing gas and substances generated from the charging means, it is possible to prevent a decrease in density in the vicinity of the charging means at high humidity and image deterioration due to image blur.

  Here, the reason why the resistance to the oxidizing gas and the substance can be improved by including the compound represented by any one of the general formulas (1) and (2) in the surface protective layer has been clarified at present. However, it is presumed that the substituted amino group contained in the structure effectively suppresses the generation of radical substances against the oxidizing gas. In addition, since the compound represented by any one of the general formulas (1) and (2) also has a charge transport capability, it does not act as a trap for the charge bile itself, and increases the residual potential accompanying the addition. Deterioration of electrical characteristics such as is hardly observed.

  Further, when the photosensitive layer contains a distyrylbenzene derivative, and the surface protective layer contains a filler, a distyrylbenzene derivative, and the compound represented by either the general formula (1) or (2), the initial residual potential is reduced. In addition, an increase in the residual potential during repeated use can be suppressed. The reason why the residual potential can be reduced by using a distyrylbenzene derivative is that the charge mobility is very high and the mobility is less dependent on the electric field strength. That is, charges can be sufficiently transferred even with a low electric field strength, and a low residual potential can be achieved. This distyrylbenzene derivative exhibits high mobility because it has a large molecular size and a linear molecular structure, and also has a plurality of triphenylamine and styryl structures in the molecular structure. This is probably because the rate of intramolecular movement is higher in charge transfer than in intermolecular transfer because the system has a feature that spreads throughout the molecule. In addition, regarding the suppression of the increase in the residual potential, the oxidation potential of the distyrylbenzene derivative is low, so that the injection barrier becomes smaller with respect to the charge injection from the charge generating material in the photosensitive layer, and the photocarrier is hardly left. It has become.

  However, when the distyrylbenzene derivative is used in the surface protective layer of the photoreceptor as described above, the compound represented by any one of the general formulas (1) and (2) may be used repeatedly and the surroundings. It has been found that image blur due to ozone, NOx, or other oxidizing substances caused by the environment becomes significant. The cause of this is presumed to be due to the low oxidation potential based on the knowledge obtained in the study of the present invention. As described above, the distyrylbenzene derivative has a linear molecular structure with a large molecular size, and has a characteristic that the π-conjugated system spreads throughout the molecule, so that the oxidation potential is low. In other words, since the oxidation potential of the charge transporting material is low, it is susceptible to chemical attack by ozone, NOx, or other oxidizing materials caused by repeated use and the surrounding environment. It is thought that the latent image will be blurred.

In a photoreceptor having a surface protective layer containing a filler, a residual potential tends to be generated originally. To reduce the residual potential, the oxidation potentials of the charge transport materials used for the photosensitive layer and the surface protective layer should be the same, or It has been considered that the oxidation potential of the surface protective layer needs to be smaller than the oxidation potential of the charge transport material (it is necessary to avoid creating a charge injection barrier between the photosensitive layer and the surface protective layer).
However, even if the oxidation potential of the charge transport material of the surface protective layer is made larger than that of the distyrylbenzene derivative of the photosensitive layer, if the surface protective layer is not thick, the increase in the residual potential and the initial residual potential are almost unchanged. I found that there was no. Image blur is dependent on the oxidation potential of the charge transport material in the surface protective layer. By increasing the oxidation potential of the charge transport material in the surface protective layer, the image blur can be suppressed, and a filler is included in the outermost layer. Thus, it is possible to reduce the initial residual potential of the photoconductor to realize higher-speed image formation, and to suppress image deterioration due to image blurring and increase in residual potential during repeated use.

In addition, when the difference in oxidation potential between the charge transport material in the surface protective layer and the charge transport material in the photosensitive layer is in the range of 0.01 V to 0.20 V, the initial residual potential is also low, and during repeated use An increase in residual potential can be suppressed, and an effect of suppressing image blur by the surface protective layer can also be obtained.
The charge transport material of the photosensitive layer represented by the general formulas (3) and (4) has a melting point of 170 ° C. or higher, a molecular structure having a large structure with a π-electron conjugated system spread, and high crystallinity. Therefore, when the surface protective layer is provided, cracks may occur at the interface between the photosensitive layer and the surface protective layer. It is preferable to suppress the occurrence of this interface crack because it is feared that it will appear in the image if it becomes severe, or that the photosensitive layer may be peeled off when the photoreceptor is repeatedly used. It is presumed that the interface crack is mainly caused by a difference in plasticity between the photosensitive layer and the surface protective layer, which is caused by a difference in thermal characteristics of the contained charge transport material. The present inventor has also found that such interfacial cracks can be suppressed by increasing the plasticity of the photosensitive layer or increasing the plasticity of the surface protective layer. That is, the amount of the charge transport material contained in the photosensitive layer is 65% by mass or more based on the resin, or a low molecular additive having a melting point of 150 ° C. or less is added to 100 parts by mass of the charge transport material contained in the photosensitive layer. On the other hand, it can be prevented by adding 2.5 parts by mass to 10 parts by mass. Further, by containing at least one of the compounds represented by the following structural formulas (1) to (3) having a melting point of 150 ° C. or lower as a low molecular additive in the photosensitive layer, not only the prevention of interface cracks, There is also an effect that image blur can be reduced, and a longer-life photoconductor is realized.
In addition, by using a charge transport material that is larger than the oxidation potential of the charge transport material used in the photosensitive layer as the charge transport material of the surface protective layer, and further using a material having a melting point of 170 ° C. or less of the charge transport material of the surface protective layer, It has also been found that the margin for preventing the above-mentioned interface crack is improved.

  Therefore, in the present invention, the occurrence of cracks is suppressed by adopting the above-described configuration, and an electrophotographic photosensitive member capable of stably and rapidly forming a high-quality image even for repeated use over a long period of time, and A more durable image forming apparatus using the electrophotographic photosensitive member and a process cartridge can be provided.

The image forming apparatus according to the present invention includes an electrophotographic photosensitive member, an electrostatic latent image forming unit for forming an electrostatic latent image on the electrophotographic photosensitive member, and developing the electrostatic latent image using toner. The electrophotographic photosensitive member comprises at least developing means for forming a visual image, transfer means for transferring the visible image to a recording medium, and fixing means for fixing the transferred image transferred to the recording medium. As described above, the electrophotographic photoreceptor of the present invention is used.
In the image forming apparatus of the present invention, the electrostatic latent image forming unit forms an electrostatic latent image. The developing means develops the electrostatic latent image formed on the electrophotographic photosensitive member with toner to form a visible image. The transfer means transfers the visible image to a recording medium. The fixing unit fixes the transferred image transferred to the recording medium. At this time, since the electrophotographic photosensitive member of the present invention is used as the electrophotographic photosensitive member, image deterioration and residual potential increase due to image blurring are suppressed, and high-quality images are stable even when used repeatedly for a long time. Can be formed.

The image forming method of the present invention includes an electrostatic latent image forming step of forming an electrostatic latent image on an electrophotographic photosensitive member, and a developing step of developing the electrostatic latent image with toner to form a visible image. And a transfer step for transferring the visible image to a recording medium, and a fixing step for fixing the transfer image transferred to the recording medium, and the electrophotographic photosensitive member of the present invention as the electrophotographic photosensitive member. Is used.
In the image forming method of the present invention, an electrostatic latent image is formed on the electrophotographic photosensitive member in the electrostatic latent image forming step. In the developing step, the electrostatic latent image formed on the electrophotographic photosensitive member is developed with toner to form a visible image. In the transfer step, the visible image is transferred to a recording medium. In the fixing step, the transferred image transferred to the recording medium is fixed. At this time, since the electrophotographic photosensitive member of the present invention is used as the electrophotographic photosensitive member, image deterioration and residual potential increase due to image blurring are suppressed, and high-quality images are stable even when used repeatedly for a long time. Can be formed.

  The process cartridge of the present invention has at least an electrophotographic photosensitive member and a developing unit that develops an electrostatic latent image formed on the electrophotographic photosensitive member with toner to form a visible image, and forms an image. It can be attached to and detached from the main body of the apparatus, is excellent in convenience, and uses the electrophotographic photosensitive member of the present invention. Therefore, it suppresses image deterioration and residual potential increase due to image blurring, and can be used repeatedly for a long time. High-quality images can be formed stably.

  According to the present invention, the conventional problems can be solved, and in the electrophotographic photosensitive member containing the filler in the surface protective layer which is the outermost surface layer, the initial residual potential can be reduced and higher-speed image formation can be realized. , An electrophotographic photosensitive member capable of stably forming a high-quality image even for repeated use over a long period of time, and image formation using the electrophotographic photosensitive member by suppressing image deterioration and residual potential increase and interface cracking due to image blurring Devices and process cartridges can be provided.

(Electrophotographic photoreceptor)
The electrophotographic photoreceptor of the present invention comprises a support, and at least a photosensitive layer and a surface protective layer on the support, and further comprises other layers as necessary.

In the present invention, the surface protective layer contains a filler, a charge transport material, and a compound represented by any one of the following general formulas (1) and (2), and further contains other components as necessary. To do. The photosensitive layer contains at least a charge transport material, the charge transport material in the photosensitive layer has an oxidation potential smaller than that of the charge transport material in the surface protective layer, and the following general formulas (3) and ( It contains the compound represented by any one of 4), and further contains other components as necessary. As a result, the initial residual potential can be reduced, and image degradation and residual potential increase due to image blur can be solved.
However, in the general formula (1), R ¹ and R ² may be the same as or different from each other, and may have an alkyl group which may have a substituent, and a substituent. Any one of the aryl groups which may be present, and at least one of R ¹ and R ^{2 is} an aryl group which may have a substituent. R ¹ and R ² may be bonded to each other to form a heterocyclic ring containing a nitrogen atom, and the heterocyclic ring may be further substituted with a substituent. Ar represents an arylene group which may have a substituent.
However, in the general formula (2), R ¹ and R ² may be the same as or different from each other, and may have an alkyl group which may have a substituent, and a substituent. Any of the aryl groups that may be present, and R ¹ and R ² may be bonded to each other to form a heterocyclic ring containing a nitrogen atom, and the heterocyclic ring is further substituted with a substituent; Also good. Ar ¹ and Ar ² each represent an arylene group which may have a substituent. l and m each represent an integer of 0 to 3, and l and m are not 0 at the same time. n represents an integer of 1 or 2.
However, in said general formula (3), R < ³ > -R < ⁶ > is the phenyl which may have a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, and a substituent, respectively. Represents any of the groups.
A represents an arylene group which may have a substituent and a substituent represented by the following structural formula (3-1).
However, in said structural formula (3-1), R < ⁷ >, R < ⁸ > and R < ⁹ > are either a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, and a phenyl group. And the phenyl group may be further substituted with a substituent.
B represents any of an aryl group which may have a substituent and a substituent represented by the following structural formula (3-2).
However, in the structural formula (3-2), Ar ³ represents an arylene group which may have a substituent. Ar ⁴ and Ar ⁵ each represents an aryl group which may have a substituent.
However, in said general formula (4), R < ¹⁰ > -R < ³⁵ > may mutually be the same and may differ, A hydrogen atom, a C1-C4 alkyl group, C1-C4 It represents either an alkoxy group or a phenyl group which may have a substituent.

-Layer structure-
The electrophotographic photosensitive member is not particularly limited with respect to the layer structure, and can be appropriately selected according to the purpose. (Sometimes referred to as a “single-layer type photosensitive layer”) and a surface protective layer, and if necessary, other layers such as an undercoat layer. In the second embodiment, a support, a photosensitive layer having a structure in which a charge generation layer and a charge transport layer are stacked on the support (hereinafter also referred to as a “stacked photosensitive layer”), And a surface protective layer and, if necessary, other layers such as an undercoat layer. In the second embodiment, the charge generation layer and the charge transport layer may be laminated in reverse.

Here, the electrophotographic photosensitive member will be described with reference to the drawings. 1 to 3 are schematic sectional views showing an example of the electrophotographic photosensitive member of the present invention.
FIG. 1 shows a charge transport material represented by any one of the general formulas (3) and (4) on the support 201, preferably at least one of the compounds represented by the structural formulas (1) to (3). A photosensitive layer 202 containing seeds is provided, and a surface protective layer 210 is provided on the photosensitive layer. The surface protective layer 210 contains the filler, the charge transport material, and the compound represented by any one of the general formulas (1) and (2).
FIG. 2 shows a charge generation layer 203 containing a charge generation material on a support 201 and a charge transport material represented by any one of the general formulas (3) and (4), preferably the structural formula (1). To a charge transport layer 204 containing at least one compound represented by (3), and further has a surface protective layer 210 on the surface of the charge transport layer. The surface protective layer 210 contains the filler, the charge transport material, and the compound represented by any one of the general formulas (1) and (2).
FIG. 3 shows a structure in which at least a charge transport material represented by any one of the general formulas (3) and (4), preferably a compound represented by the structural formulas (1) to (3), is formed on a support 201. A charge transport layer 204 containing one kind and a charge generation layer 203 containing a charge generation material are stacked, and a surface protective layer 210 is further provided on the surface of the charge generation layer 203. The surface protective layer 210 contains the filler, the charge transport material, and the compound represented by any one of the general formulas (1) and (2).

<Surface protective layer>
The surface protective layer is provided as an outermost surface layer of the photoreceptor for the purpose of protecting the photosensitive layer and improving durability, and is any one of the general formulas (3) and (4) contained in the filler and the photosensitive layer. A charge transport material having an oxidation potential larger than that of the charge transport material and a compound represented by any one of the general formulas (1) and (2), preferably a binder resin, an acid value of 10 to 10. It contains 700 mg KOH / g organic compound, and further contains other components as required.
However, in the general formula (1), R ¹ and R ² may be the same as or different from each other, and may have an alkyl group which may have a substituent, and a substituent. Any one of the aryl groups which may be present, and at least one of R ¹ and R ^{2 is} an aryl group which may have a substituent. R ¹ and R ² may be bonded to each other to form a heterocyclic ring containing a nitrogen atom, and the heterocyclic ring may be further substituted with a substituent. Ar represents an arylene group which may have a substituent.
However, in the general formula (2), R ¹ and R ² may be the same as or different from each other, and may have an alkyl group which may have a substituent, and a substituent. Any of the aryl groups that may be present, and R ¹ and R ² may be bonded to each other to form a heterocyclic ring containing a nitrogen atom, and the heterocyclic ring is further substituted with a substituent; Also good. Ar ¹ and Ar ² each represent an arylene group which may have a substituent. l and m each represent an integer of 0 to 3, and l and m are not 0 at the same time. n represents an integer of 1 or 2.

-Filler-
As the filler, either an organic filler or an inorganic filler is used. Examples of the organic filler include fluorine resin powder such as polytetrafluoroethylene; silicon resin powder, a-carbon powder, and the like. Examples of the inorganic filler include metal powders such as copper, tin, aluminum, and indium; doped with silica, tin oxide, zinc oxide, titanium oxide, alumina, zirconium oxide, indium oxide, antimony oxide, bismuth oxide, calcium oxide, and antimony. Metal oxides such as tin oxide and tin-doped indium oxide; metal fluorides such as tin fluoride, calcium fluoride and aluminum fluoride; potassium titanate and boron nitride. Among these, from the viewpoint of the hardness of the filler, the use of an inorganic filler is advantageous for improving the wear resistance.

  Further, as the filler that hardly causes image blur, a filler having high electrical insulation is preferable. As such a filler, a filler having a pH of 5 or more or a filler having a dielectric constant of 5 or more is particularly effective, and examples thereof include metal oxides such as titanium oxide, alumina, zinc oxide, and zirconium oxide. In addition, a filler having a pH of 5 or more or a filler having a dielectric constant of 5 or more can be used alone. Two or more fillers having a pH of 5 or less and a filler having a pH of 5 or more can be mixed, or the dielectric constant can be used. It is also possible to use a mixture of two or more fillers having a dielectric constant of 5 or less and fillers having a dielectric constant of 5 or more. Among these fillers, α-type alumina, which has a high insulating property, high thermal stability, and high wear resistance, is a hexagonal close-packed structure, which suppresses image blurring and improves wear resistance. Is particularly useful from

When the dispersibility of the filler is reduced, not only the residual potential is increased, but also the transparency of the outermost layer and the occurrence of coating film defects are caused, and further the wear resistance is decreased. Therefore, the filler is at least one surface treatment. It is preferable that the surface is treated with an agent.
The surface treatment agent is not particularly limited and can be appropriately selected from conventionally used surface treatment agents according to the purpose, but a surface treatment agent capable of maintaining the insulating properties of the filler is preferable. Titanate coupling agent, aluminum coupling agent, zircoaluminate coupling agent, higher fatty acid, or mixed treatment with these and silane coupling agent; Al ₂ O ₃ , TiO ₂ , ZrO ₂ , silicon, stearic acid Aluminum or a mixed treatment thereof is more preferable from the viewpoints of filler dispersibility and prevention of image blurring. Although the influence of image blur is increased by the surface treatment with the silane coupling agent, the influence may be suppressed by performing a mixing treatment of the surface treatment agent and the silane coupling agent. The amount of the surface treatment agent varies depending on the average primary particle size of the filler used, but is preferably 3% by mass to 30% by mass, and more preferably 5% by mass to 20% by mass. When the surface treatment amount is less than this, the filler dispersion effect cannot be obtained, and when the surface treatment amount is too much, the residual potential may be significantly increased.

The average primary particle size of the filler is preferably 0.01 μm to 1.0 μm, and more preferably 0.05 μm to 0.8 μm. When the average primary particle size is less than 0.01 μm, wear resistance and dispersibility may be deteriorated. When the average primary particle size exceeds 1.0 μm, the sedimentation property of the filler is promoted, Filming may occur.
The average primary particle size of the filler can be determined by directly measuring the particle size, for example, by observation with an electron microscope.

  5 mass%-50 mass% are preferable, and, as for content in the said surface protective layer of the said filler, 10 mass%-40 mass% are more preferable. If the content is less than 5% by mass, the wear resistance is not sufficient, but if it exceeds 50% by mass, the transparency of the surface protective layer may be impaired. In this case, when a filler is contained on the surface of the photosensitive layer, the filler can be contained in the entire photosensitive layer, but the filler concentration is such that the outermost surface side of the charge transport layer has the highest filler concentration and the support side becomes lower. It is preferable to provide a structure in which a slope is provided, or a plurality of charge transport layers are provided to increase the filler concentration sequentially from the support side to the surface side.

-Organic compound having an acid value of 10 mgKOH / g to 700 mgKOH / g-
When the surface protective layer in the photosensitive member contains a filler, it is possible to achieve high durability and avoid the so-called image blur, but the influence of the increase in residual potential increases. In order to suppress this increase in residual potential, it is preferable to add an organic compound having an acid value of 10 mgKOH / g to 700 mgKOH / g.

Here, the acid value is defined as the number of milligrams of potassium hydroxide required to neutralize the free fatty acid contained in 1 g, and can be measured by a method defined in JIS K2501 or the like.
The organic compound having an acid value of 10 mgKOH / g to 700 mgKOH / g is not particularly limited, and examples thereof include organic fatty acids and resins having an acid value of 10 mgKOH / g to 700 mgKOH / g. However, very low molecular weight maleic acid, citric acid, tartaric acid, succinic acid and other organic acids, acceptors, etc. may significantly reduce the dispersibility of the filler, so the residual potential is sufficiently reduced. It may not be demonstrated. Therefore, in order to reduce the residual potential of the photoreceptor and to increase the dispersibility of the filler, it is preferable to use a low molecular weight polymer, resin, copolymer, etc., and further a mixture thereof. Moreover, as a structure of the said organic compound, it is more preferable to have a linear structure with little steric hindrance. In order to improve the dispersibility, it is necessary to give affinity to both the filler and the binder resin, and the material having a large steric hindrance decreases the dispersibility due to a decrease in their affinity. This leads to many problems as described above.
From this point, as the organic compound having an acid value of 10 mgKOH / g to 700 mgKOH / g, polycarboxylic acid is preferable. The polycarboxylic acid is a compound having a structure containing a carboxylic acid in a polymer or copolymer, such as a polyester resin, an acrylic resin; a copolymer using acrylic acid or methacrylic acid, a styrene acrylic copolymer, etc. Any organic compound containing acid or its derivative can be used. These can be used in combination of two or more. In some cases, mixing these materials with organic fatty acids may increase the dispersibility of the filler or the accompanying residual potential reduction effect.

  The acid value of the organic compound is preferably 10 mgKOH / g to 700 mgKOH / g, more preferably 30 mgKOH / g to 400 mgKOH / g. If the acid value is too high, the resistance is too low and the influence of image blur increases, and if the acid value is too low, it is necessary to increase the amount of addition, and the effect of reducing the residual potential becomes insufficient. The acid value of the organic compound having an acid value of 10 mgKOH / g to 700 mgKOH / g needs to be determined by a balance with the amount added. Even with the same addition amount, if the acid value is high, the residual potential reduction effect is not high, and the effect is greatly related to the adsorptivity of the organic compound having an acid value of 10 to 700 mgKOH / g to the filler.

The content of the organic compound having an acid value of 10 mgKOH / g to 700 mgKOH / g is determined by the acid value and the filler content. That is, the content of the organic compound having the acid value of 10 mgKOH / g to 700 mgKOH / g is A, the acid value of the organic compound having the acid value of 10 mgKOH / g to 700 mgKOH / g is B, and the content of the filler is C. It is preferable that the following relational expression 1 is satisfied among A, B and C.
<Relational expression 1>
0.2 ≦ acid value equivalent (A × B / C) ≦ 20
If the content of the organic compound having an acid value of 10 to 700 mgKOH / g is too large, it may cause a poor dispersion or a strong influence of image blur. On the other hand, if the content is too small, dispersion may occur. Defects and residual potential reduction effects may be insufficient.

The filler can be dispersed together with at least an organic solvent and an organic compound having an acid value of 10 mgKOH / g to 700 mgKOH / g using a ball mill, an attritor, a sand mill, an ultrasonic wave, or the like. Among these, the contact efficiency between the filler and the organic compound having an acid value of 10 mgKOH / g to 700 mgKOH / g can be increased, and dispersion by a ball mill with less mixing of impurities from the outside is more preferable from the viewpoint of dispersibility. As for the material of the media used, all media such as zirconia, alumina, and agate conventionally used can be used, but alumina is particularly preferred from the viewpoint of filler dispersibility and residual potential reduction effect.
The zirconia has a large amount of media wear at the time of dispersion, and the residual potential is remarkably increased by mixing them. In addition, the dispersibility is greatly reduced by the mixing of the wear powder, and the sedimentation property of the filler is promoted. On the other hand, when alumina is used as the medium, the medium is worn during dispersion, but the amount of wear is kept low and the influence of the mixed wear powder on the residual potential is very small. Further, even if wear powder is mixed, since there is little adverse effect on the dispersibility, it is preferable to use alumina as a medium used for dispersion.

  The organic compound having an acid value of 10 mgKOH / g to 700 mgKOH / g is added together with the filler and the organic solvent before dispersion, thereby suppressing the aggregation of the filler in the coating liquid and further the sedimentation property of the filler. Since dispersibility is remarkably improved, it is preferable to add it before dispersion. On the other hand, the binder resin and the charge transport material can be added before dispersion, but in this case, the dispersibility is slightly lowered. Therefore, the binder resin and the charge transport material are preferably added after being dispersed in a state dissolved in an organic solvent.

  The organic compound having an acid value of 10 mg KOH / g to 700 mg KOH / g is derived from its chemical structure, and easily adsorbs oxidizing gases such as ozone and NOx generated by the surrounding environment and corona discharge charging means. May reduce the resistance of the outermost surface and cause problems such as image flow.

-Compound represented by either general formula (1) or (2)-
In the present invention, in order to solve the above problem, the surface protective layer has a charge transport having a larger oxidation potential than the charge transport material represented by any one of the general formulas (3) and (4) contained in the photosensitive layer. It contains a substance and contains a compound represented by any one of the following general formulas (1) and (2).

However, in the general formula (1), R ¹ and R ² may be the same as or different from each other, and may have an alkyl group which may have a substituent, and a substituent. Any one of the aryl groups which may be present, and at least one of R ¹ and R ^{2 is} an aryl group which may have a substituent. R ¹ and R ² may be bonded to each other to form a heterocyclic ring containing a nitrogen atom, and the heterocyclic ring may be further substituted with a substituent. Ar represents an arylene group which may have a substituent.
However, in the general formula (2), R ¹ and R ² may be the same as or different from each other, and may have an alkyl group which may have a substituent, and a substituent. Any of the aryl groups that may be present, and R ¹ and R ² may be bonded to each other to form a heterocyclic ring containing a nitrogen atom, and the heterocyclic ring is further substituted with a substituent; Also good. Ar ¹ and Ar ² each represent an arylene group which may have a substituent. l and m each represent an integer of 0 to 3, and l and m are not 0 at the same time. n represents an integer of 1 or 2.

Examples of the alkyl group in the general formula (1) or (2) include a methyl group, an ethyl group, a propyl group, an isopropyl group, a butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a pentyl group, and an isopentyl group. Group, neopentyl group, hexyl group, heptyl group, octyl group, nonyl group, decyl group, undecyl group, undecanyl group, dodecyl group, vinyl group, benzyl group, phenethyl group, styryl group, cyclopentyl group, cyclohexyl group, cycloheptyl group And cyclohexenyl group.
Examples of the aryl group in the general formula (1) or (2) include a phenyl group, a tolyl group, a xylyl group, a styryl group, a naphthyl group, an anthryl group, and a biphenyl group.
The alkyl group in R ¹ and R ² in the general formula (2) is preferably substituted with an aromatic hydrocarbon group. Examples of the aromatic hydrocarbon group include aromatic ring groups such as benzene, biphenyl, naphthalene, anthracene, fluorene, and pyrene; aromatic heterocyclic groups such as pyridine, quinoline, thiophene, furan, oxazole, oxadiazole, and carbazole. Etc.
In the case where R ¹ and R ² are bonded to each other to form a heterocyclic group containing a nitrogen atom, the heterocyclic group is a condensed pyrrolidino group, piperidino group, piperazino group or the like condensed with an aromatic hydrocarbon group. A heterocyclic group can be mentioned.
Examples of these substituents include those exemplified in the specific examples of the alkyl group, alkoxy groups such as methoxy group, ethoxy group, propoxy group, and butoxy group; halogens such as fluorine atom, chlorine atom, bromine atom, and iodine atom. Atoms: the aromatic hydrocarbon groups; heterocyclic groups such as pyrrolidine, piperidine, piperazine and the like.

The diamine compound represented by either of the general formulas (1) and (2) is described in literature (E. Elce and AS Hay, Polymer, Vol. 37 No. 9, 1745 (1996)). It can be easily manufactured by the method. Specifically, a dihalide represented by the following general formula (a) and a secondary amine compound represented by the following general formula (b) at a temperature of room temperature to 100 ° C. in the presence of a basic compound. It is obtained by reacting.
_{XH 2 C-Ar-CH 2} X ··· formula (a)
In the general formula (a), Ar represents the same meaning as in the general formula (1), and X represents a halogen atom.
However, in said general formula (b), R < ¹ > and R < ² > represent the same meaning as the said general formula (1).

  The basic compound is not particularly limited and may be appropriately selected depending on the intended purpose. For example, potassium carbonate, sodium carbonate, potassium hydroxide, sodium hydroxide, sodium hydride, sodium methylate, potassium-t- Examples include butoxide. The reaction solvent is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include dioxane, tetrahydrofuran, toluene, xylene, dimethyl sulfoxide, N, N-dimethylformamide, N-methylpyrrolidone, 1,3- Examples thereof include dimethyl-2-imidazolidinone and acetonitrile.

  Hereinafter, specific examples of the compound represented by any one of the general formulas (1) and (2) will be given. However, it is not limited to these compounds.

  The content of the compound represented by any one of the general formulas (1) and (2) in the surface protective layer is preferably 1% by mass to 60% by mass, and more preferably 2% by mass to 50% by mass.

  In the case where the compound represented by any one of the general formulas (1) and (2) is used in combination with an organic compound having an acid value of 10 mgKOH / g to 700 mgKOH / g, it is necessary to store the coating solution. In order to suppress the formation of salt due to interaction, it is preferable to contain a specific antioxidant. The formation of this salt not only causes discoloration of the coating solution, but may cause problems such as an increase in residual potential in the produced electrophotographic photosensitive member.

  As the antioxidant that can be used in the electrophotographic photosensitive member of the present invention, the general antioxidants described later can be used, and among these, hydroquinone and hindered amine compounds are particularly preferable. However, the antioxidant used here is added for the purpose of protecting the compound represented by any one of the general formulas (1) and (2) in the coating solution, unlike the purpose of addition described later. . For this reason, it is preferable to make the said antioxidant contain in the coating liquid in the process before containing the compound represented by either of the said General formula (1) and (2). The addition amount of the antioxidant is 0.1 to 200 parts by mass with respect to 100 parts by mass of the organic compound having an acid value of 10 to 700 mgKOH / g in order to achieve sufficient storage stability of the coating solution over time. Is preferred.

Further, as the charge transport material of the surface protective layer, image blurring may be used as long as it has a higher oxidation potential than the charge transport material represented by any one of the general formulas (3) and (4) contained in the photosensitive layer. Can be suppressed.
The difference between the oxidation potential of the charge transport material in the surface protective layer and the oxidation potential of the charge transport material in the photosensitive layer (surface protective layer-photosensitive layer) is preferably 0.01 V or more, and 0.02 V to 0.20 V. More preferred.
Here, a method for measuring the oxidation potential of the charge transport material, that is, the first oxidation half-wave potential is described below. A substance to be measured is dissolved by adding a predetermined amount of methylene chloride and an irrelevant salt (supporting electrolyte) such as tetrabutylammonium perchlorate or tetraethylammonium perchlorate to obtain a test solution. With respect to this test solution, the oxidation potential of the target substance can be measured by an electrochemical analysis means such as polarograph or cyclic voltammetry. Regarding the electrochemical analysis, A.I. J. et al. Bard, L .; R. He is familiar with books such as “Electrochemical Methods” by Faulkner published in 1980 by Wiley. Here, a dropping mercury electrode is used as a working electrode, a noble metal such as platinum or gold is used as a counter electrode, a saturated sweet potato electrode (SCE) is used as a reference electrode, and the potential scanning method using a potentiostat can be used.

  The oxidation potential of the charge transport material in the surface protective layer is preferably 0.76 V to 0.90 V (vs SCE). When the oxidation potential is less than 0.76 V, image blur tends to occur, and when it exceeds 0.90 V, the compound represented by any one of the general formulas (3) and (4) used for the photosensitive layer is used. Although depending on the oxidation potential, the charge injection barrier between the photosensitive layer and the surface protective layer may become large, and the residual potential may easily increase.

As the charge transport material in the surface protective layer, as described above, any substance having an oxidation potential larger than that of the compound represented by any one of the general formulas (3) and (4) contained in the photosensitive layer may be used. There is no restriction | limiting, According to the objective, it can select suitably, For example, the compound etc. which are shown by the following general formula (a)-the following general formula (r) are mentioned.
Further, as described above, in order to suppress cracks that are likely to occur at the interface between the photosensitive layer and the surface protective layer, the charge transport material having a melting point of 170 ° C. or lower is selected as the charge transport material for the surface protective layer. It is more preferable. The melting point of the charge transport material contained in the surface protective layer is more preferably 160 ° C. or lower, which increases the crack prevention effect.

In the general formula (a), R ¹ represents a methyl group, an ethyl group, 2-hydroxyethyl group or a 2-chloroethyl group, R ² represents a methyl group, an ethyl group, a benzyl group or a phenyl radical, R ³ represents a hydrogen atom, a chlorine atom, a bromine atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms, a dialkylamino group, or a nitro group.

However, in said general formula (b), Ar represents a naphthalene ring, anthracene ring, a pyrene ring, and those substituted products, or a pyridine ring, a furan ring, and a thiophene ring, and R represents an alkyl group, a phenyl group, or a benzyl group.

However, the general formula (c), R ¹ is an alkyl group, a benzyl group, a phenyl group or naphthyl group, R ² represents a hydrogen atom, an alkyl group having 1 to 3 carbon atoms, an alkoxy group having 1 to 3 carbon atoms , A dialkylamino group, a diaralkylamino group, or a substituted or unsubstituted diarylamino group, n represents an integer of 1 to 4, and when n is 2 or more, R ² may be the same or different. R ³ represents a hydrogen atom or a methoxy group.

In the general formula (d), R ¹ is an alkyl group having 1 to 11 carbon atoms, a substituted or unsubstituted phenyl group or a heterocyclic group, R ^2, R ³ may be different from each other in the same Represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, a hydroxyalkyl group, a chloroalkyl group, or a substituted or unsubstituted aralkyl group, and R ² and R ³ are bonded to each other to form a nitrogen-containing heterocyclic ring. It may be. R ⁴ may be the same or different and represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group, or a halogen atom.

However, in said general formula (e), R represents a hydrogen atom or a halogen atom, Ar represents a substituted or unsubstituted phenyl group, a naphthyl group, an anthryl group, or a carbazolyl group.

Table In the general formula (f), R ¹ represents a hydrogen atom, a halogen atom, a cyano group, an alkoxy group having 1 to 4 carbon atoms, or an alkyl group having 1 to 4 carbon atoms, Ar is by the following structural formula Represents a substituent.
In Structural Formula, R ² represents an alkyl group having 1 to 4 carbon atoms, R ³ is a hydrogen atom, a halogen atom, an alkyl group having 1 to 4 carbon atoms, 1 to 4 carbon atoms alkoxy group or a dialkylamino Represents a group, n is 1 or 2, and when n is 2, R ³ may be the same or different.
R ⁴ and R ⁵ each represent a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 4 carbon atoms, or a substituted or unsubstituted benzyl group.

However, in the general formula (g), R is a carbazolyl group, pyridyl group, thienyl group, indolyl group, furyl group or a substituted or unsubstituted phenyl group, styryl group, naphthyl group, or anthryl group, and From a dialkylamino group, alkyl group, alkoxy group, carboxy group or ester thereof, halogen atom, cyano group, aralkylamino group, N-alkyl-N-aralkylamino group, amino group, nitro group and acetylamino group Represents a selected group.

However, in the general formula (h), R ¹ represents a lower alkyl group, a substituted or unsubstituted phenyl group, or a benzyl group.
R ² and R ³ each represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, a halogen atom, a nitro group, an amino group, an amino group substituted with a lower alkyl group or a benzyl group, and n is an integer of 1 or 2 Represents.

However, in the above formula (i), R ¹ represents a hydrogen atom, an alkyl group, an alkoxy group or a halogen atom. R ² and R ³ each represents a substituted or unsubstituted aryl group. R ⁴ represents a hydrogen atom, a lower alkyl group, or a substituted or unsubstituted phenyl group. Ar represents a substituted or unsubstituted phenyl group or naphthyl group.

In the general formula (j), n represents an integer of 0 or 1, R ¹ represents a hydrogen atom, an alkyl group, or a substituted or unsubstituted phenyl group. Ar1 represents a substituted or unsubstituted aryl group. R ⁵ represents an alkyl group containing a substituted alkyl group, or a substituted or unsubstituted aryl group. When m is 2 or more, R ² may be the same or different. When n is 0, A and R ¹ may form a ring together.
A represents a substituent represented by the following structural formula, a 9-anthryl group, or a substituted or unsubstituted carbazolyl group.
R ² represents a hydrogen atom, an alkyl group, an alkoxy group, a halogen atom, or a substituent represented by the following structural formula.
In Structural Formula, R ³ and R ⁴ represents a substituted or unsubstituted aryl group, wherein R ³ and R ⁴ may be the same or different, wherein R ⁴ may form a ring .

However, in said general formula (k), R < ¹ >, R < ² > and R < ³ > represent a hydrogen atom, a lower alkyl group, a lower alkoxy group, a halogen atom, or a dialkylamino group, respectively. n represents 0 or 1.

However, in said general formula (l), R < ¹ > and R < ² > represents the alkyl group containing a substituted alkyl group, respectively, or a substituted or unsubstituted aryl group. A represents a substituted amino group, a substituted or unsubstituted aryl group, or an allyl group.

However, in said general formula (m), X represents a hydrogen atom, a lower alkyl group, or a halogen atom. R represents a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. A represents a substituted amino group or a substituted or unsubstituted aryl group.

In the general formula (n), R ¹ represents a lower alkyl group, a lower alkoxy group or a halogen atom. R ² and R ³ may be the same or different and each represents a hydrogen atom, a lower alkyl group, a lower alkoxy group or a halogen atom. l, m, and n each represent an integer of 0-4.

However, in said general formula (o), R < ¹ >, R < ³ > and R < ⁴ > are respectively a hydrogen atom, an amino group, an alkoxy group, a thioalkoxy group, an aryloxy group, a methylenedioxy group, a substituted or unsubstituted alkyl group. Represents a halogen atom or a substituted or unsubstituted aryl group. R ² represents a hydrogen atom, an alkoxy group, a substituted or unsubstituted alkyl group, or a halogen atom. However, except that R ¹ , R ² , R ³ and R ⁴ are all hydrogen atoms, k, l, m and n are integers of 1, 2, 3 or 4, each of which is 2, When it is an integer of 3 or 4, the R ¹ , R ² , R ³ and R ⁴ may be the same or different.

However, in the general formula (p), Ar represents a condensed polycyclic hydrocarbon group having 18 or less carbon atoms which may have a substituent. R ¹ and R ² represent a hydrogen atom, a halogen atom, a substituted or unsubstituted alkyl group, an alkoxy group, or a substituted or unsubstituted phenyl group, and may be the same or different. n represents an integer of 1 or 2.

A-CH = CH-Ar-CH = CH-A General formula (q)
In the general formula (q), Ar represents a substituted or unsubstituted aromatic hydrocarbon group.
A represents a substituent represented by the following structural formula.
In the structural formula, Ar ′ represents a substituted or unsubstituted aromatic hydrocarbon group, and R ¹ and R ² represent a substituted or unsubstituted alkyl group or a substituted or unsubstituted aryl group, respectively. .

However, in said general formula (r), Ar represents a substituted or unsubstituted aromatic hydrocarbon group. R represents a hydrogen atom, a substituted or unsubstituted alkyl group, or a substituted or unsubstituted aryl group. n is 0 or 1, m is 1 or 2, and when n = 0 and m = 1, Ar and R may form a ring together.

Examples of the compound represented by the general formula (a) include 9-ethylcarbazole-3-aldehyde-1-methyl-1-phenylhydrazone, 9-ethylcarbazole-3-aldehyde-1-benzyl-1-phenyl. And hydrazone, 9-ethylcarbazole-3-aldehyde-1,1-diphenylhydrazone, and the like.
Examples of the compound represented by the general formula (b) include 4-diethylaminostyryl-β-aldehyde-1-methyl-1-phenylhydrazone, 4-methoxynaphthalene-1-aldehyde-1-benzyl-1-phenyl. And hydrazone.
Examples of the compound represented by the general formula (c) include 4-methoxybenzaldehyde-1-methyl-1-phenylhydrazone, 2,4-dimethoxybenzaldehyde-1-benzyl-1-phenylhydrazone, and 4-diethylaminobenzaldehyde. -1,1-diphenylhydrazone, 4-methoxybenzaldehyde-1- (4-methoxy) phenylhydrazone, 4-diphenylaminobenzaldehyde-1-benzyl-1-phenylhydrazone, 4-dibenzylaminobenzaldehyde-1,1-diphenyl And hydrazone.

Examples of the compound represented by the general formula (d) include 1,1-bis (4-dibenzylaminophenyl) propane, tris (4-diethylaminophenyl) methane, 1,1-bis (4-dibenzyl). Aminophenyl) propane, 2,2′-dimethyl-4,4′-bis (diethylamino) -triphenylmethane, and the like.
Examples of the compound represented by the general formula (e) include 9- (4-diethylaminostyryl) anthracene, 9-bromo-10- (4-diethylaminostyryl) anthracene, and the like.
Examples of the compound represented by the general formula (f) include 9- (4-dimethylaminobenzylidene) fluorene, 3- (9-fluorenylidene) -9-ethylcarbazole, and the like.
Examples of the compound represented by the general formula (g) include 1,2-bis (4-diethylaminostyryl) benzene, 1,2-bis (2,4-dimethoxystyryl) benzene, and the like.
Examples of the compound represented by the general formula (h) include 3-styryl-9-ethylcarbazole, 3- (4-methoxystyryl) -9-ethylcarbazole, and the like.

Examples of the compound represented by the general formula (i) include 4-diphenylaminostilbene, 4-dibenzylaminostilbene, 4-ditolylaminostilbene, 1- (4-diphenylaminostyryl) naphthalene, 1- ( 4-diphenylaminostyryl) naphthalene, and the like.
Examples of the compound represented by the general formula (j) include 4′-diphenylamino-α-phenylstilbene, 4′-bis (4-methylphenyl) amino-α-phenylstilbene, and the like.
Examples of the compound represented by the general formula (k) include 1-phenyl-3- (4-diethylaminostyryl) -5- (4-diethylaminophenyl) pyrazoline.
Examples of the compound represented by the general formula (l) include 2,5-bis (4-diethylaminophenyl) -1,3,4-oxadiazole, 2-N, N-diphenylamino-5- ( 4-diethylaminophenyl) -1,3,4-oxadiazole, 2- (4-dimethylaminophenyl) -5- (4-diethylaminophenyl) -1,3,4-oxadiazole, and the like.
Examples of the compound represented by the general formula (m) include 2-N, N-diphenylamino-5- (N-ethylcarbazol-3-yl) -1,3,4-oxadiazole, 2- (4-diethylaminophenyl) -5- (N-ethylcarbazol-3-yl) -1,3,4-oxadiazole and the like.
Examples of the benzidine compound represented by the general formula (n) include N, N′-diphenyl-N, N′-bis (3-methylphenyl)-[1,1′-biphenyl] -4,4 ′. -Diamine, 3,3'-dimethyl-N, N, N ', N'-tetrakis (4-methylphenyl)-[1,1'-biphenyl] -4,4'-diamine, and the like.

Examples of the biphenylylamine compound represented by the general formula (o) include 4′-methoxy-N, N-diphenyl- [1,1′-biphenyl] -4-amine, 4′-methyl-N, N-bis (4-methylphenyl)-[1,1′-biphenyl] -4-amine, 4′-methoxy-N, N-bis (4-methylphenyl)-[1,1′-biphenyl] -4 -Amine, N, N-bis (3,4-dimethylphenyl)-[1,1'-biphenyl] -4-amine, and the like.
Examples of the triarylamine compound represented by the general formula (p) include N, N-diphenyl-pyrene-1-amine, N, N-di-p-tolyl-pyren-1-amine, and N, N. -Di-p-tolyl-1-naphthylamine, N, N-di (p-tolyl) -1-phenanthrylamine, 9,9-dimethyl-2- (di-p-tolylamino) fluorene, N, N, N ', N'-tetrakis (4-methylphenyl) -phenanthrene-9,10-diamine, N, N, N', N'-tetrakis (3-methylphenyl) -m-phenylenediamine, and the like.

Examples of the diolefin aromatic compound represented by the general formula (q) include 1,4-bis (4-diphenylaminostyryl) benzene and 1,4-bis [4-di (p-tolyl) aminostyryl. ] Benzene, etc.
Examples of the styrylpyrene compound represented by the general formula (r) include 1- (4-diphenylaminostyryl) pyrene, 1- (N, N-di-p-tolyl-4-aminostyryl) pyrene, and the like. Can be mentioned.

-Binder resin-
There is no restriction | limiting in particular as binder resin in the said surface protective layer, According to the objective, it can select suitably. For example, AS resin, ABS resin, ACS resin, olefin-vinyl monomer copolymer, chlorinated polyether resin, allyl resin, phenol resin, polyacetal resin, polyamide resin, polyamideimide resin, polyacrylate resin, polyallylsulfone resin, Polybutylene resin, polybutylene terephthalate resin, polycarbonate resin, polyethersulfone resin, polyethylene resin, polyethylene terephthalate resin, polyimide resin, acrylic resin, polymethylpentene resin, polypropylene resin, polyphenylene oxide resin, polysulfone resin, polyurethane resin, polyvinyl chloride Examples thereof include resins, polyvinylidene chloride resins, and epoxy resins.
Note that the addition of the low molecular charge transport material or the high molecular charge transport material mentioned in the charge transport layer described later to the surface protective layer is effective and useful for reducing the residual potential and improving the image quality.

  The method for forming the surface protective layer is not particularly limited and may be appropriately selected depending on the intended purpose. For example, a dip coating method, a spray coating method, a beat coating method, a nozzle coating method, a spinner coating method, a ring coating method. Etc. Among these, the spray coating method is particularly preferable from the viewpoint of the uniformity of the coating film. In addition, it is possible to apply the required thickness of the surface protective layer at a time to form a surface protective layer, but it is more than twice that the surface protective layer is applied in multiple layers in the layer. More preferable in terms of uniformity of the filler. As a result, a further effect can be obtained with respect to reduction of residual potential, improvement of resolution, and improvement of wear resistance.

  The thickness of the surface protective layer is preferably 0.1 μm to 10 μm, and more preferably 2.0 μm to 8.0 μm. By adding the organic compound having an acid value of 10 to 700 mgKOH / g, the residual potential can be greatly reduced, and thereby the thickness of the surface protective layer can be freely set. However, when the thickness of the surface protective layer is remarkably increased, it is recognized that the image quality tends to be slightly degraded.

<Support>
The support is not particularly limited as long as it has a volume resistance of 10 ¹⁰ Ω · cm or less, and can be appropriately selected according to the purpose. For example, aluminum, nickel, chromium, nichrome, copper Metals such as gold, silver and platinum; metal oxides such as tin oxide and indium oxide deposited or sputtered on a film or cylindrical plastic, paper or aluminum, aluminum alloy, nickel, stainless steel, etc. Or a tube subjected to surface treatment such as cutting, super-finishing, polishing or the like after being made into a raw tube by a method such as extruding and drawing them. Further, an endless nickel belt and an endless stainless steel belt disclosed in JP-A-52-36016 can also be used as a support. Further, it may be a nickel foil having a thickness of 50 μm to 150 μm, or a surface of a polyethylene terephthalate film having a thickness of 50 μm to 150 μm subjected to conductive processing such as aluminum vapor deposition.

In addition, those in which conductive powder is dispersed in an appropriate binder resin and coated on the support can also be used as the support of the present invention.
Examples of the conductive powder include carbon black, acetylene black, metal powder such as aluminum, nickel, iron, nichrome, copper, zinc, and silver, or metal oxide powder such as conductive tin oxide and ITO. Etc. The binder resin used at the same time includes polystyrene resin, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polyester resin, polyvinyl chloride resin, vinyl chloride-vinyl acetate. Copolymer, polyvinyl acetate resin, polyvinylidene chloride resin, polyarylate resin, phenoxy resin, polycarbonate resin, cellulose acetate resin, ethyl cellulose resin, polyvinyl butyral resin, polyvinyl formal resin, polyvinyl toluene resin, poly-N-vinyl carbazole, An acrylic resin, a silicone resin, an epoxy resin, a melamine resin, a urethane resin, a phenol resin, an alkyd resin, etc. are mentioned.
The conductive layer can be provided by dispersing and applying these conductive powder and binder resin in a suitable solvent such as tetrahydrofuran, dichloromethane, methyl ethyl ketone, toluene and the like.

  Furthermore, it is electrically conductive by a heat shrinkable tube in which the conductive powder is contained in a material such as polyvinyl chloride, polypropylene, polyester, polystyrene, polyvinylidene chloride, polyethylene, chlorinated rubber, Teflon (registered trademark) on a suitable cylindrical substrate. Those provided with a conductive layer can also be used favorably as a conductive support.

<Photosensitive layer>
-Multilayer photosensitive layer-
The multilayer photosensitive layer has a charge generation layer and a charge transport layer, and, as described above, has a lower oxidation potential than the charge transport material contained in the surface protective layer, the general formulas (3) and (4) ) Is included in the charge transport layer.

-Charge generation layer-
The charge generation layer includes at least a charge generation material, and includes a binder resin and, if necessary, other components.
The charge generation layer is a layer mainly composed of a charge generation material. A known charge generation material can be used for the charge generation layer. For example, monoazo pigments, disazo pigments, asymmetrical disazo pigments, trisazo pigments, azo pigments having a carbazole skeleton (JP-A-53-95033), azo pigments having a distyrylbenzene skeleton (JP-A-53-133445) Azo pigment having a triphenylamine skeleton (Japanese Patent Laid-Open No. 53-132347), an azo pigment having a diphenylamine skeleton, an azo pigment having a dibenzothiophene skeleton (Japanese Patent Laid-Open No. 54-21728), and a fluorenone skeleton. Azo pigments having an oxadiazol skeleton (Japanese Patent Laid-Open No. 54-12742), azo pigments having a bis-stilbene skeleton (Japanese Patent Laid-Open No. 54-17733) , An azo pigment having a distyryl oxadiazol skeleton (Japanese Patent Laid-Open No. 54-212) Azo pigments such as azo pigments having a distyrylcarbazole skeleton (Japanese Patent Laid-Open No. 54-14967); azulenium salt pigments, squalic acid methine pigments, perylene pigments, anthraquinone or polycycles A quinone pigment, a quinoneimine pigment, a diphenylmethane and triphenylmethane pigment, a benzoquinone and a naphthoquinone pigment, a cyanine and azomethine pigment, an indigoid pigment, a bisbenzimidazole pigment, or the following general formula (A) Phthalocyanine pigments such as metal phthalocyanine and metal-free phthalocyanine.
However, in the general formula (A), M (central metal) represents a metal or metal-free (hydrogen) element.
There is no restriction | limiting in particular as said M (center metal), According to the objective, it can select suitably, For example, H, Li, Be, Na, Mg, Al, Si, K, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga, Ge, Y, Zr, Nb, Mo, Tc, Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Ba, Hf, Ta, W, Re, Os, Ir, Pt, Au, Hg, TI, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, Th, Pa, It consists of a single element such as U, Np and Am, or two or more elements such as oxide, chloride, fluoride, hydroxide and bromide.

  The charge generation material having the phthalocyanine skeleton only needs to have at least the basic skeleton of the general formula (A), those having a multimeric structure such as a dimer or trimer, and higher-order polymers. It may have a structure or may have various substituents on the basic skeleton. Of these various phthalocyanines, titanyl phthalocyanine having TiO as a central metal, metal-free phthalocyanine, chlorogallium phthalocyanine, hydroxygallium phthalocyanine, and the like are particularly preferable in terms of photoreceptor characteristics. These phthalocyanines are known to have various crystal systems. For example, in the case of titanyl phthalocyanine, α, β, γ, m, Y type copper phthalocyanines, α, β, γ And so on. Even in the phthalocyanine having the same central metal, various characteristics change as the crystal system changes. It has been reported that the characteristics of photoreceptors using phthalocyanine pigments having these various crystal systems also change accordingly (Electrophotographic Society Vol. 29, No. 4, (1990)). Therefore, the selection of the phthalocyanine crystal system is very important in terms of the photoreceptor characteristics.

  Among these phthalocyanine pigments, titanyl phthalocyanine crystals having a maximum diffraction peak at least 27.2 ° as a diffraction peak (± 0.2 °) with a Bragg angle 2θ with respect to the characteristic X-ray (1.542 °) of CuKα are particularly high. In the present invention, the speed can be increased, so that it is used particularly effectively. Among them, it has a maximum diffraction peak at 27.2 °, and further has main peaks at 9.4 °, 9.6 °, and 24.0 °, and the lowest diffraction peak is 7.3 °. The titanyl phthalocyanine crystal having a peak at 7.3 ° and no peak between the 7.3 ° peak and the 9.4 ° peak and no peak at 26.3 ° has a large charge generation efficiency. They can also be used very effectively as the charge generating material of the present invention because they have good electrostatic properties and are less likely to cause scumming. These charge generation materials can be used alone or as a mixture of two or more.

  The charge generating substance is effective because the effect may be enhanced by making the particle size finer. In particular, in the phthalocyanine pigment, the average particle size is preferably 0.25 μm or less, and more preferably 0.2 μm or less. The manufacturing method is shown below. A method for controlling the particle size of the charge generating material contained in the photosensitive layer is a method of removing coarse particles larger than 0.25 μm after dispersing the charge generating material. The average particle size referred to here is a volume average particle size, and is determined by an ultracentrifugal automatic particle size distribution analyzer: CAPA-700 (manufactured by Horiba, Ltd.). At this time, the particle diameter (Median diameter) corresponding to 50% of the cumulative distribution was calculated. However, this method may not be able to detect a very small amount of coarse particles, so in order to obtain more details, it is important to observe the charge generation material powder or dispersion directly with an electron microscope and determine the size. It is.

  Next, a method of removing coarse particles after dispersing the charge generation material will be described. That is, it is a method in which a dispersion liquid having as fine a particle as possible is prepared and then filtered through an appropriate filter. For the preparation of the dispersion, a general method is used, and it is obtained by dispersing the charge generation material in a suitable solvent together with a binder resin, if necessary, using a ball mill, attritor, sand mill, bead mill, ultrasonic wave, or the like. It is At this time, the binder resin may be selected depending on the electrostatic characteristics of the photoreceptor, and the solvent may be selected depending on the wettability to the pigment, the dispersibility of the pigment, and the like.

  This method is a very effective means from the viewpoint that it can be observed visually (or cannot be detected by particle size measurement), can remove the remaining trace amount of coarse particles, and can even the particle size distribution. Specifically, the dispersion prepared as described above is filtered through a filter having an effective pore diameter of 5 μm or less, more preferably 3 μm or less, thereby completing the dispersion. Also by this method, a dispersion containing only a charge generating substance having a small particle size (0.25 μm or less, preferably 0.2 μm or less) can be prepared. By using this, a static property such as sensitivity and chargeability can be obtained. The electric characteristics are improved, the effect is sustained, and the effect of the present invention can be enhanced.

  At this time, when the particle size of the dispersion to be filtered is too large or the particle size distribution is too wide, the loss due to filtration becomes large or the filtration becomes clogged and filtration becomes impossible. There is a case. For this reason, in the dispersion before filtration, it is preferable to perform dispersion until the average particle size is 0.3 μm or less and the standard deviation reaches 0.2 μm or less. When the average particle size is 0.3 μm or more, the loss due to filtration increases, and when the standard deviation is 0.2 μm or more, there may be a problem that the filtration time becomes very long.

  The charge generation material has an extremely strong intermolecular hydrogen bonding force, which is a characteristic of charge generation materials exhibiting highly sensitive characteristics. For this reason, the interaction between the dispersed pigment particles is very strong. As a result, there is a great possibility that the charge generation material particles dispersed by a disperser etc. are re-aggregated by dilution or the like. Such agglomerates can be removed. At this time, since the dispersion is in a thixotropic state, particles having a size smaller than the effective pore size of the filter to be used are removed. Alternatively, a liquid exhibiting structural viscosity can be changed to a state close to Newtonian by filtering. Thus, the effect of the present invention can be further improved by removing the coarse particles of the charge generating material.

Among the azo pigments, azo pigments represented by the following general formula (B) are effectively used. In particular, an asymmetric azo pigment in which Cp ₁ and Cp ₂ of the azo pigment are different from each other has a large carrier generation efficiency and is effective for increasing the speed, and is preferably used as the charge generation material of the present invention.
However, the general formula (B), Cp ₁ and Cp ₂ represent a coupler residue. R ₂₀₁ and R ₂₀₂ each represent a hydrogen atom, a halogen atom, an alkyl group, an alkoxy group, or a cyano group, and may be the same or different. Cp ₁ and Cp ₂ are represented by the following structural formula.
However, in the structural formula, R ₂₀₃ represents a hydrogen atom, an alkyl group such as a methyl group or an ethyl group, or an aryl group such as a phenyl group.
R ₂₀₄ , R ₂₀₅ , R ₂₀₆ , R ₂₀₇ , and R ₂₀₈ are each a hydrogen atom, a nitro group, a cyano group; a halogen atom such as fluorine, chlorine, bromine, or iodine; a halogenated alkyl group such as a trifluoromethyl group; An alkyl group such as a methyl group or an ethyl group; an alkoxy group such as a methoxy group or an ethoxy group; a dialkylamino group or a hydroxyl group. Z represents a group of atoms necessary for constituting a substituted or unsubstituted carbocyclic aromatic group aromatic carbocyclic ring or a substituted or unsubstituted heterocyclic aromatic group aromatic heterocyclic ring.

  The binder resin used as necessary for the charge generation layer is not particularly limited and can be appropriately selected according to the purpose. For example, polyamide, polyurethane, epoxy resin, polyketone, polycarbonate, silicone resin, acrylic resin, Polyvinyl butyral, polyvinyl formal, polyvinyl ketone, polystyrene, poly-N-vinyl carbazole, polyacrylamide, polyvinyl benzal, polyester, phenoxy resin, vinyl chloride-vinyl acetate copolymer, polyvinyl acetate, polyphenylene oxide, polyvinyl pyridine, Cellulose resin, casein, polyvinyl alcohol, polyvinyl pyrrolidone, etc. are mentioned. Among these, polyvinyl butyral is particularly preferable. These may be used individually by 1 type and may use 2 or more types together.

  Examples of the solvent include generally used organic solvents such as isopropanol, acetone, methyl ethyl ketone, cyclohexanone, tetrahydrofuran, dioxane, ethyl cellosolve, ethyl acetate, methyl acetate, dichloromethane, dichloroethane, monochlorobenzene, cyclohexane, toluene, xylene, and ligroin. Among these, it is preferable to use a ketone solvent, an ester solvent, or an ether solvent. These may be used individually by 1 type and may use 2 or more types together.

  The charge generation layer may be obtained by dispersing a charge generation material in a solvent using a known dispersion method such as a ball mill, an attritor, a sand mill, or an ultrasonic wave together with a binder resin as necessary. it can. The binder resin may be added before or after the charge generating material is dispersed. The coating solution for the charge generation layer is mainly composed of a charge generation material, a solvent, and a binder resin, and it contains additives such as a sensitizer, a dispersant, a surfactant, and silicone oil. May be. In some cases, it is also possible to add a charge transport material described later to the charge generation layer. The addition amount of the binder resin is preferably 500 parts by mass or less, more preferably 10 parts by mass to 300 parts by mass with respect to 100 parts by mass of the charge generation material.

  The charge generation layer is formed by coating on a conductive support or an undercoat layer using the coating liquid and drying. As the coating method, known methods such as dip coating, spray coating, bead coating, nozzle coating, spinner coating, ring coating, and the like can be used. The thickness of the charge generation layer is preferably 0.01 μm to 5 μm, and more preferably 0.1 μm to 2 μm. Further, drying after coating is performed by heating using an oven or the like. The drying temperature of the charge generation layer is preferably 50 ° C to 160 ° C, more preferably 80 ° C to 140 ° C.

-Charge transport layer-
The charge transport layer is a layer intended to hold a charged charge and to couple the charge generated and separated in the charge generation layer by exposure to the charged charge held by movement. In order to achieve the purpose of holding the charged charge, it is required that the electric resistance is high. Further, in order to achieve the purpose of obtaining a high surface potential with the charged charge that has been held, it is required that the dielectric constant is small and the charge mobility is good.

The charge transport layer is mainly composed of a charge transport material and a binder resin. As the charge transport material, a low molecular charge transport material such as a hole transport material or an electron transport material is used, and a polymer charge transport material can be added as necessary.
Examples of the electron transporting material (electron accepting material) include chloranil, bromanyl, tetracyanoethylene, tetracyanoquinodimethane, 2,4,7-trinitro-9-fluorenone, 2,4,5,7-tetranitro. -9-fluorenone, 2,4,5,7-tetranitroxanthone, 2,4,8-trinitrothioxanthone, 2,6,8-trinitro-4H-indeno [1,2-b] thiophene-4-one, 1,3,7-trinitrodibenzothiophene-5,5-dioxide, and the like. These may be used individually by 1 type and may use 2 or more types together.

Examples of the hole transport material (electron donating material) include oxazole derivatives, oxadiazole derivatives, imidazole derivatives, triphenylamine derivatives, 9- (p-diethylaminostyrylanthracene), 1,1-bis- (4 -Dibenzylaminophenyl) propane, styrylanthracene, styrylpyrazoline, phenylhydrazones, α-phenylstilbene derivatives, thiazole derivatives, triazole derivatives, phenazine derivatives, acridine derivatives, benzofuran derivatives, benzimidazole derivatives, thiophene derivatives, etc. It is done.
Among these hole transport materials, a compound containing a distyryl structure is effective for suppressing the residual potential rise, and an oxidation potential of 0.76 V (vs SCE) or less is preferable although it depends on the charge generation material of the photosensitive layer. . Above all, the compound represented by the following general formula (3) can reduce the initial residual potential and suppress the increase of the residual potential during repeated use, resulting in higher image quality, higher speed, smaller equipment, and shorter image output time. It becomes extremely effective in the conversion.
However, in said general formula (3), R < ³ > -R < ⁶ > is the phenyl which may have a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, and a substituent, respectively. Represents any of the groups.
A represents an arylene group which may have a substituent and a substituent represented by the following structural formula (3-1).
However, in said structural formula (3-1), R < ⁷ >, R < ⁸ > and R < ⁹ > are either a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, and a phenyl group. And the phenyl group may be further substituted with a substituent.
B represents any of an aryl group which may have a substituent and a substituent represented by the following structural formula (3-2).
However, in the structural formula (3-2), Ar ³ represents an arylene group which may have a substituent. Ar ⁴ and Ar ⁵ each represents an aryl group which may have a substituent.

Among these compounds, the distyrylbenzene derivative represented by the following general formula (4) is particularly effective, effective and useful in the present invention.
However, in said general formula (4), R < ¹⁰ > -R < ³⁵ > may mutually be the same and may differ, A hydrogen atom, a C1-C4 alkyl group, C1-C4 It represents either an alkoxy group or a phenyl group which may have a substituent.

  These compounds are considered to be effective factors that have high mobility, but the compound represented by the above general formula (3), particularly the distyrylbenzene derivative represented by the above general formula (4) is In contrast, it is a very effective material. These molecules have a relatively large and linear molecular structure, and the π-conjugated system spreads throughout the molecule, which makes intramolecular movement more than intermolecular movement of charge. Thus, it is considered that the dependence of the mobility on the electric field strength is reduced as the mobility is improved.

In order to reduce the initial residual potential and suppress the increase in the residual potential during repeated use, the photosensitive layer may contain a compound represented by any one of the general formulas (3) and (4) and the hole transport agent or The polymer charge transport materials may be combined and contained.
Further, the charge transport material of the photosensitive layer represented by any one of the general formulas (3) and (4) has a melting point of 170 ° C. to 240 ° C., and the molecular structure has a large structure with a π-electron conjugated system spread. Therefore, when the surface protective layer is provided, cracks may occur at the interface between the photosensitive layer and the surface protective layer. It is preferable to suppress the occurrence of this interface crack because it is feared that it will appear in the image if it becomes severe, or that the photosensitive layer may be peeled off when the photoreceptor is repeatedly used. It is presumed that the interface crack is mainly caused by a difference in plasticity between the photosensitive layer and the surface protective layer, which is caused by a difference in thermal characteristics of the contained charge transport material. Such interfacial cracks can be suppressed by increasing the plasticity of the photosensitive layer or increasing the plasticity of the surface protective layer.
Accordingly, the photosensitive layer is composed of an additive amount of charge transport material contained in the photosensitive layer of 65 parts by mass or more with respect to 100 parts by mass of the resin, or a low molecular additive having a melting point of 150 ° C. or less added to the photosensitive layer. It is more preferable to add 2.5 parts by mass to 10 parts by mass with respect to 100 parts by mass of the contained charge transport material, and these can prevent interface cracks. Further, by containing at least one of the compounds represented by the following structural formulas (1) to (3) having a melting point of 150 ° C. or less as a low molecular additive in the photosensitive layer, the image is not limited only to prevention of interface cracks, but also to an image. There is also an effect that blur can be reduced, and a longer-life photoconductor is realized.

In addition, by using a charge transport material that is larger than the oxidation potential of the charge transport material used in the photosensitive layer as the charge transport material of the surface protective layer, and further using a material having a melting point of 170 ° C. or less of the charge transport material of the surface protective layer, The margin for preventing the above-mentioned interface crack can be improved.

Specific examples of the charge transport material represented by any one of the general formulas (3) and (4) in the photosensitive layer are shown below. However, these are merely examples, and the present invention is not limited to these specific examples.
However, Me represents a methyl group.
However, Me represents a methyl group.
However, Me represents a methyl group.
However, Me represents a methyl group.
However, Me represents a methyl group.
However, Me represents a methyl group.
However, Me represents a methyl group.
However, Me represents a methyl group.
However, Me represents a methyl group.
However, Me represents a methyl group.
However, Me represents a methyl group.

Examples of the polymer charge transport material include those having the following structure.
Examples of (a) a polymer having a carbazole ring include, for example, poly-N-vinylcarbazole, JP-A-50-82056, JP-A-54-9632, JP-A-54-11737, JP-A-5-11737. Examples thereof include compounds described in JP-A-4-175337, JP-A-4-183719, and JP-A-6-234841.
(B) Examples of the polymer having a hydrazone structure include, for example, JP-A-57-78402, JP-A-61-20953, JP-A-61-296358, JP-A-1-134456, Compounds described in Kaihei 1-179164, JP-A-3-180851, JP-A-3-180852, JP-A-3-50555, JP-A-5-310904, and JP-A-6-234840 Etc. are exemplified.
(C) Examples of the polysilylene polymer include, for example, JP-A-63-285552, JP-A-1-88461, JP-A-4-264130, JP-A-4-264131, and JP-A-4-264132. Examples thereof include compounds described in JP-A-4-264133 and JP-A-4-289867.
(D) As a polymer having a triarylamine structure, for example, N, N-bis (4-methylphenyl) -4-aminopolystyrene, JP-A-1-134457, JP-A-2-282264, Examples thereof include compounds described in Kaihei 2-304456, JP-A-4-133605, JP-A-4-133066, JP-A-5-40350, and JP-A-5-202135.
(E) As other polymers, for example, a formaldehyde condensation polymer of nitropyrene, JP-A-51-73888, JP-A-56-15049, JP-A-6-234363, JP-A-6-234837 And the compounds described in Japanese Patent Publication No.

  In addition to the above, the polymer charge transporting material includes, for example, a polycarbonate resin having a triarylamine structure, a polyurethane resin having a triarylamine structure, a polyester resin having a triarylamine structure, and a triarylamine structure. And a polyether resin. Examples of the polymer charge transporting material include JP-A 64-1728, JP-A 64-13061, JP-A 64-19049, JP-A-4-11627, JP-A 4-116627. JP 2225014, JP 4-230767, JP 4-320420, JP 5-232727, JP 7-56374, JP 9-127713, JP 9-222740. And compounds described in JP-A-9-265197, JP-A-9-211877, JP-A-9-30495, and the like.

  Examples of the polymer having an electron donating group include not only the above-mentioned polymer but also a copolymer with a known monomer, a block polymer, a graft polymer, a star polymer, It is also possible to use a crosslinked polymer having an electron donating group as disclosed in JP-A-109406.

Examples of the binder resin include polystyrene, styrene-acrylonitrile copolymer, styrene-butadiene copolymer, styrene-maleic anhydride copolymer, polycarbonate resin, polyester resin, methacrylic resin, acrylic resin, polyethylene resin, polychlorinated resin. Vinyl resin, polyvinyl acetate resin, polystyrene resin, phenol resin, epoxy resin, polyurethane resin, polyvinylidene chloride resin, alkyd resin, silicone resin, polyvinyl carbazole resin, polyvinyl butyral resin, polyvinyl formal resin, polyacrylate resin, polyacrylamide resin , Phenoxy resin, and the like. These may be used individually by 1 type and may use 2 or more types together.
The charge transport layer may also contain a copolymer of a crosslinkable binder resin and a crosslinkable charge transport material.
65 mass parts-200 mass parts are preferable with respect to 100 mass parts of said binder resins, and, as for content of the said charge transport material, 70 mass parts-150 mass parts are more preferable.

The charge transport layer can be formed by dissolving or dispersing these charge transport materials and a binder resin in an appropriate solvent, applying the solution, and drying. In addition to the charge transport material and the binder resin, an appropriate amount of additives such as a plasticizer, an antioxidant, and a leveling agent may be added to the charge transport layer as necessary.
The thickness of the charge transport layer is preferably 40 μm or less from the viewpoint of resolution and responsiveness, and the lower limit is preferably 15 μm or more, although it varies depending on the system used (particularly the charging potential).

-Single layer photosensitive layer-
The single-layer photosensitive layer is a charge transport material represented by any one of the general formulas (3) and (4) having an oxidation potential smaller than that of the charge transport material and the charge transport material contained in the surface protective layer. It is formed by dissolving or dispersing a binder resin or the like in an appropriate solvent, applying the solution on a conductive support or an undercoat layer, and drying.

For the details of the charge generation material and the charge transport material (electron transport material and hole transport material), it is possible to use the materials mentioned in the charge generation layer and the charge transport layer. Further, as the binder resin, in addition to the resins mentioned in the charge transport layer, the resins mentioned in the charge generation layer may be mixed and used. Examples of other components include plasticizers, fine particles, and various additives. Note that the above-described polymer charge transporting material can also be used favorably as the binder resin.
The content of the charge generation material is preferably 5 to 40 parts by mass, more preferably 10 to 30 parts by mass with respect to 100 parts by mass of the binder resin. Moreover, 190 mass parts or less are preferable with respect to 100 mass parts of said binder resins, and, as for content of the said charge transport material, 50 mass parts-150 mass parts are more preferable.

The single-layer type photosensitive layer is dissolved or dispersed in a solvent such as tetrahydrofuran, dioxane, dichloroethane, cyclohexanone, toluene, methyl ethyl ketone, and acetone together with the charge generation material, the binder resin, and the charge transport material, and this is dip-coated. It can be formed by coating with a spray coat, bead coat, ring coat or the like. If necessary, various additives such as a plasticizer, a leveling agent, an antioxidant and a lubricant can be added.
The thickness of the single-layer type photosensitive layer is preferably 5 μm to 25 μm. The single-layer type photosensitive layer has a shorter charge transport distance to the surface of the image carrier than the laminated structure. However, it is not necessarily expensive. Although a single layer configuration is effective, a stacked configuration is more suitable for achieving the effect in the present invention.
The thickness of the single-layer type photosensitive layer is not particularly limited and can be appropriately selected according to the purpose, and is preferably 10 μm to 40 μm.

-Undercoat layer-
An undercoat layer may be provided between the support and the photosensitive layer as necessary. The undercoat layer is provided for the purpose of improving adhesiveness, preventing moire, improving the coatability of the upper layer, and reducing residual potential.

The undercoat layer contains at least a resin and fine powder, and further contains other components as necessary.
Examples of the resin include water-soluble resins such as polyvinyl alcohol resin, casein, and sodium polyacrylate; alcohol-soluble resins such as copolymer nylon and methoxymethylated nylon; polyurethane resins, melamine resins, alkyd-melamine resins, and epoxy resins. And a curable resin that forms a three-dimensional network structure.
Examples of the fine powder include metal oxides such as titanium oxide, silica, alumina, zirconium oxide, tin oxide, and indium oxide, metal sulfides, and metal nitrides.
Moreover, what contains a silane coupling agent, a titanium coupling agent, a chromium coupling agent etc. as an undercoat layer can also be used. Further, as an undercoat layer, an anodized layer of Al ₂ O ₃ , an organic material such as polyparaxylylene (parylene), or an inorganic material such as SiO ₂ , SnO ₂ , TiO ₂ , ITO, or CeO ₂ is vacuum thin film. Those provided by the manufacturing method can also be used.
There is no restriction | limiting in particular about the thickness of the said undercoat layer, According to the objective, it can select suitably, 0.1 micrometer-10 micrometers are preferable, and 1 micrometer-5 micrometers are more preferable.

  In the photoreceptor, an intermediate layer may be provided on the support, if necessary, in order to improve adhesion and charge blocking properties. The intermediate layer contains a resin as a main component, and these resins are preferably resins having a high solvent resistance with respect to an organic solvent in consideration of applying a photosensitive layer thereon with a solvent. As the resin, the same resin as the undercoat layer can be appropriately selected and used.

-Additives-
In the electrophotographic photoreceptor of the present invention, in order to improve environmental resistance, in particular, for the purpose of preventing a decrease in sensitivity and an increase in residual potential, a charge generation layer, a charge transport layer, an undercoat layer, a surface protective layer, a single protective layer, Antioxidants, plasticizers, lubricants, ultraviolet absorbers, low molecular charge transport materials, leveling agents and the like can be added to each layer such as a layer-type photosensitive layer.

  For the suppression of cracks that are likely to occur at the interface between the photosensitive layer and the surface protective layer as described above, a low molecular additive having a melting point of 150 ° C. or lower is added to the amount of charge transport material contained in the photosensitive layer. It is more preferable to add 2.5 mass%-10 mass%. By incorporating at least one of the compounds represented by the following structural formulas (1) to (3) having a melting point of 150 ° C. or less as the low molecular additive into the photosensitive layer, not only the prevention of interface cracks but also the image This is particularly preferable because there is an effect that blur can be reduced and a photoconductor having a longer life is realized.

Examples of the antioxidant include phenolic compounds, paraphenylenediamines, 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-t-butylphenol), 4,4'-butylidenebis- (3-methyl-6-t-butylphenol), 1,1,3-tris- (2-methyl-4-hydroxy-5-t- Butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) 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, tocopherol 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.
The addition amount of the antioxidant is preferably 0.01% by mass to 10% by mass with respect to the total mass of the layer to be added.

  Moreover, there is no restriction | limiting in particular as a plasticizer which can be added to each layer, According to the objective, it can select suitably, For example, a phosphate ester plasticizer, a phthalate ester plasticizer, an aromatic carboxylate ester plasticizer, Aliphatic dibasic acid ester plasticizer, fatty acid ester derivative, oxyester plasticizer, epoxy plasticizer, dihydric alcohol ester plasticizer, chlorine-containing plasticizer, polyester plasticizer, sulfonic acid derivative, citric acid derivative And other plasticizers.

Examples of the phosphate ester plasticizer include triphenyl phosphate, tricresyl phosphate, trioctyl phosphate, octyl diphenyl phosphate, trichloroethyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, and tri-2-phosphate. Examples include ethylhexyl and triphenyl phosphate.
Examples of the phthalate ester plasticizer include dimethyl phthalate, diethyl phthalate, diisobutyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, diisooctyl phthalate, and di-n-octyl phthalate. , Dinonyl phthalate, diisononyl phthalate, diisodecyl phthalate, diundecyl phthalate, ditridecyl phthalate, dicyclohexyl phthalate, butyl benzyl phthalate, butyl lauryl phthalate, methyl oleyl phthalate, octyl decyl phthalate, dibutyl fumarate, fumarate Examples include acid dioctyl.
Examples of the aromatic carboxylic acid ester plasticizer include trioctyl trimellitic acid, tri-n-octyl trimellitic acid, octyl oxybenzoate, and the like.
Examples of the aliphatic dibasic acid ester plasticizer include dibutyl adipate, di-n-hexyl adipate, di-2-ethylhexyl adipate, di-n-octyl adipate, and adipic acid n-octyl-n. -Decyl, diisodecyl adipate, dicapryl adipate, di-2-ethylhexyl azelate, dimethyl sebacate, diethyl sebacate, dibutyl sebacate, di-n-octyl sebacate, di-2-ethylhexyl sebacate, dibasic sebacate Examples include 2-ethoxyethyl, dioctyl succinate, diisodecyl succinate, dioctyl tetrahydrophthalate, and di-n-octyl tetrahydrophthalate.
Examples of the fatty acid ester derivatives include butyl oleate, glycerin monooleate, methyl acetylricinoleate, pentaerythritol ester, dipentaerythritol hexaester, triacetin, and tributyrin.
Examples of the oxyester plasticizer include methyl acetyl ricinoleate, butyl acetyl ricinoleate, butyl phthalyl butyl glycolate, and tributyl acetyl citrate.
Examples of the epoxy plasticizer include epoxidized soybean oil, epoxidized linseed oil, epoxy butyl stearate, decyl epoxy stearate, octyl epoxy stearate, benzyl epoxy stearate, dioctyl epoxy hexahydrophthalate, epoxy hexahydrophthalic acid Examples include didecyl.
Examples of the dihydric alcohol ester plasticizer include diethylene glycol dibenzoate and triethylene glycol di-2-ethylbutyrate.
Examples of the chlorine-containing plasticizer include chlorinated paraffin, chlorinated diphenyl, chlorinated fatty acid methyl, and methoxychlorinated fatty acid methyl.
Examples of the polyester plasticizer include polypropylene adipate, polypropylene sebacate, polyester, and acetylated polyester.
Examples of the sulfonic acid derivative include p-toluenesulfonamide, o-toluenesulfonamide, p-toluenesulfoneethylamide, o-toluenesulfoneethylamide, toluenesulfone-N-ethylamide, p-toluenesulfone-N-cyclohexylamide. Etc.
Examples of the citric acid derivative include triethyl citrate, triethyl acetyl citrate, tributyl citrate, tributyl acetyl citrate, tri-2-ethylhexyl acetyl citrate, and acetyl citrate-n-octyldecyl.
Examples of the other plasticizers include terphenyl, partially hydrogenated terphenyl, camphor, 2-nitrodiphenyl, dinonylnaphthalene, and methyl abietic acid.

  The lubricant that can be added to each layer is not particularly limited and can be appropriately selected depending on the purpose. For example, hydrocarbon compounds, fatty acid compounds, fatty acid amide compounds, ester compounds, alcohol compounds, metal soaps, Natural wax, other lubricants and the like can be mentioned.

Examples of the hydrocarbon compound include liquid paraffin, paraffin wax, microwax, and low-polymerized polyethylene.
Examples of the fatty acid compounds include lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, and behenic acid.
Examples of the fatty acid amide compounds include stearylamide, palmitylamide, oleinamide, methylene bisstearamide, ethylene bisstearamide, and the like.
Examples of the ester compounds include lower alcohol esters of fatty acids, polyhydric alcohol esters of fatty acids, and fatty acid polyglycol esters.
Examples of the alcohol compound include cetyl alcohol, stearyl alcohol, ethylene glycol, polyethylene glycol, and polyglycerol.
Examples of the metal soap include lead stearate, cadmium stearate, barium stearate, calcium stearate, zinc stearate, magnesium stearate and the like.
Examples of the natural wax include carnauba wax, candelilla wax, beeswax, whale wax, ibota wax, and montan wax.
Examples of the other lubricants include silicone compounds and fluorine compounds.

  There is no restriction | limiting in particular as an ultraviolet absorber which can be added to each layer, According to the objective, it can select suitably, For example, a benzophenone type ultraviolet absorber, a salicylate type ultraviolet absorber, a benzotriazole type ultraviolet absorber, a cyanoacrylate type ultraviolet ray Absorbers, quencher (metal complex salt) ultraviolet absorbers, HALS (hindered amines) and the like can be mentioned.

Examples of the benzophenone-based ultraviolet absorber include 2-hydroxybenzophenone, 2,4-dihydroxybenzophenone, 2,2 ′, 4-trihydroxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone, 2,2 Examples include '-dihydroxy 4-methoxybenzophenone.
Examples of the salicylate ultraviolet absorber include phenyl salicylate and 2,4-di-t-butylphenyl-3,5-di-t-butyl-4-hydroxybenzoate.
Examples of the benzotriazole-based ultraviolet absorber include (2′-hydroxyphenyl) benzotriazole, (2′-hydroxy5′-methylphenyl) benzotriazole, (2′-hydroxy5′-methylphenyl) benzotriazole, ( 2′-hydroxy 3′-tertiarybutyl 5′-methylphenyl) 5-chlorobenzotriazole and the like.
Examples of the cyanoacrylate ultraviolet absorber include ethyl-2-cyano-3,3-diphenyl acrylate and methyl 2-carbomethoxy 3 (paramethoxy) acrylate.
Examples of the quencher (metal complex salt) ultraviolet absorber include nickel (2,2′thiobis (4-t-octyl) phenolate) normal butylamine, nickel dibutyldithiocarbamate, nickel dibutyldithiocarbamate, cobalt dicyclohexyldithiophosphate, and the like. Is mentioned.
Examples of the HALS (hindered amine) include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, 1- [2- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] ethyl] -4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl Oxy] -2,2,6,6-tetramethylpyridine, 8-benzyl-7,7,9,9-tetramethyl-3-octyl-1,3,8-triazaspiro [4,5] undecane-2, Examples include 4-dione and 4-benzoyloxy-2,2,6,6-tetramethylpiperidine.

(Image forming apparatus and image forming method)
The image forming apparatus according to the present invention includes at least an electrophotographic photosensitive member, a charging unit, an exposure unit, a developing unit, a transfer unit, and a fixing unit. Means, for example, a craning means, a static elimination means, a lubricant applying means, a recycling means, a control means, etc.
The electrophotographic photoreceptor is the electrophotographic photoreceptor of the present invention.
The image forming method used in the present invention includes at least a charging step, an exposure step, a development step, a transfer step, and a fixing step, and further other steps appropriately selected as necessary, for example, a craning step. , A static elimination process, a lubricant application process, a recycling process, a control process, and the like.

  The image forming method used in the present invention can be preferably implemented by the image forming apparatus of the present invention, the charging step can be performed by the charging unit, and the exposure step can be performed by the exposing unit. The developing step can be performed by the developing unit, the transferring step can be performed by the transferring unit, the fixing step can be performed by the fixing unit, and the cleaning step can be performed by the cleaning unit. The other steps can be performed by the other means.

-Charging step and charging means-
The charging step is a step of charging the surface of the electrophotographic photosensitive member, and is performed by the charging unit.
The charging means is not particularly limited as long as it can uniformly apply a voltage to the surface of the electrophotographic photosensitive member, and can be appropriately selected depending on the purpose. A non-contact charging means for charging the photoconductor in a non-contact manner is used.
The non-contact charging means includes, for example, a non-contact charger and a needle electrode device using a corona discharge, a solid discharge element; a conductive or semiconductive material disposed with a small gap with respect to the electrophotographic photosensitive member. And a charging roller. Among these, corona discharge is particularly preferable.

The corona discharge is a non-contact charging method that gives positive or negative ions generated by corona discharge in the air to the surface of the electrophotographic photosensitive member, and has a characteristic of giving a certain amount of charge to the electrophotographic photosensitive member. There are a charger and a scorotron charger having a characteristic of giving a constant potential.
The coroton charger is composed of a casing electrode that occupies a half space around the discharge wire, and a discharge wire placed almost at the center thereof.
The scorotron charger is obtained by adding a grid electrode to the corotron charger, and the grid electrode is provided at a position 1.0 mm to 2.0 mm away from the surface of the electrophotographic photosensitive member.

-Exposure process and exposure means-
The exposure can be performed, for example, by exposing the surface of the electrophotographic photosensitive member imagewise using the exposure unit.
The optical system in the exposure is roughly classified into an analog optical system and a digital optical system. The analog optical system is an optical system that directly projects an original onto an electrophotographic photosensitive member by an optical system, and the digital optical system receives image information as an electrical signal, converts this into an optical signal, and converts it into an electrophotographic image. It is an optical system that exposes a photoreceptor to form an image.
The exposure unit is not particularly limited as long as the surface of the electrophotographic photosensitive member charged by the charging unit can be exposed like an image to be formed, and can be appropriately selected according to the purpose. However, various exposure devices 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. Among these, one that is either a semiconductor laser (LD) or a light emitting diode (LED) and that performs writing of an electrostatic latent image on an electrophotographic photosensitive member in a digital manner using the exposure means is particularly preferable.
A light source incorporating a multi-beam writing head in which a plurality of the semiconductor laser (LD) elements are arranged in the main scanning direction or sub-scanning direction of the photosensitive member may be used.
Here, FIG. 12 shows an example of the multi-beam exposure means used in the present invention.
A plurality of laser beams emitted from a light source 301 in which a plurality of light emitting points 301 a are arranged one-dimensionally or two-dimensionally are constrained in parallel or substantially parallel by a collimating lens 302, and are rotated through a cylindrical lens 303 and an aperture 304 ( (Polygon mirror) 305 is deflected in the main scanning direction. The laser beam deflected by the rotary polygon mirror becomes convergent light by the first scanning lens 306a and the second scanning lens 306b, and the surface of the photoconductor 308 through the first reflecting mirror 307a, the second reflecting mirror 307b, and the third reflecting mirror 307c. And is scanned in the main scanning direction.
As the light source of the multi-beam exposure means, an edge emitting laser and a surface emitting laser can be used. In particular, the surface emitting laser can form a laser array in which the light emitting points are two-dimensionally arranged, and is effective in increasing the speed and size of the image forming apparatus and improving the image resolution.
In the present invention, an optical backside system that performs imagewise exposure from the backside of the electrophotographic photosensitive member may be employed.

-Development process and development means-
The developing step is a step of developing the electrostatic latent image using a toner or a developer to form a visible image.
The visible image can be formed, for example, by developing the electrostatic latent image using the toner or the developer, and can be performed by the developing unit.
The developing unit is not particularly limited as long as it can be developed using, for example, the toner or the developer, and can be appropriately selected from known ones. For example, the toner or developer is accommodated. Preferred examples include those having at least a developing unit capable of bringing the toner or developer into contact or non-contact with the electrostatic latent image.

  The developing unit may be a dry developing type, a wet developing type, a single color developing unit, or a multi-color developing unit. For example, a toner having a stirrer for charging the toner or the developer by frictional stirring and a rotatable magnet roller is preferable.

  In the developing device, for example, the toner and the carrier are mixed and agitated, and the toner is charged by friction at that time, and held on the surface of the rotating magnet roller in a raised state to form a magnetic brush. . Since the magnet roller is disposed in the vicinity of the electrophotographic photosensitive member (photosensitive member), a part of the toner constituting the magnetic brush formed on the surface of the magnet roller is caused by an electric attractive force. It moves to the surface of the electrophotographic photoreceptor. As a result, the electrostatic latent image is developed with the toner, and a visible image is formed with the toner on the surface of the electrophotographic photosensitive member.

  The developer accommodated in the developing device is a developer containing the toner, but the developer may be a one-component developer or a two-component developer.

-Transfer process and transfer means-
The transfer step is a step of transferring the visible image onto a recording medium. After the primary transfer of the visible image onto the intermediate transfer member using an intermediate transfer member, the visible image is transferred onto the recording medium. A primary transfer step of forming a composite transfer image by transferring a visible image onto an intermediate transfer body using two or more colors, preferably full color toner as the toner, and a composite transfer image; A mode including a secondary transfer step of transferring the transfer image onto the recording medium is more preferable.
The transfer can be performed, for example, by charging the electrophotographic photosensitive member with the transfer charger using the visible image, and can be performed by the transfer unit. The transfer means includes a primary transfer means for transferring a visible image onto an intermediate transfer member to form a composite transfer image, and a secondary transfer means for transferring the composite transfer image onto a recording medium. Embodiments are preferred.
The intermediate transfer member is not particularly limited and may be appropriately selected from known transfer members according to the purpose. For example, a transfer belt and the like are preferable.

The transfer unit (the primary transfer unit and the secondary transfer unit) includes at least a transfer unit that peels and charges the visible image formed on the electrophotographic photosensitive member toward the recording medium. preferable. There may be one transfer means or two or more transfer means. Examples of the transfer device include a corona transfer device using corona discharge, a transfer belt, a transfer roller, a pressure transfer roller, and an adhesive transfer device.
The recording medium is typically plain paper, but is not particularly limited as long as it can transfer an unfixed image after development, and can be appropriately selected according to the purpose. PET for OHP A base or the like can also be used.

-Fixing Step and Fixing Unit The fixing step is a step of fixing the visible image transferred to the recording medium using a fixing device, and may be performed each time the toner of each color is transferred to the recording medium. Alternatively, the toners of the respective colors may be simultaneously formed in a state where they are laminated.

The fixing unit is not particularly limited and may be appropriately selected depending on the intended purpose. A fixing unit and a heat source for heating the fixing member are used.
Examples of the fixing member include a combination of an endless belt and a roller, a combination of a roller and a roller, etc., but the warm-up time can be shortened, and in terms of realizing energy saving, A combination of an endless belt and a roller having a small heat capacity is preferable in terms of expansion of the fixable width.

The neutralization step is a step of performing neutralization by applying a neutralization bias to the electrophotographic photosensitive member, and can be suitably performed by a neutralization unit.
The neutralizing means is not particularly limited and may be appropriately selected from known neutralizers as long as it can apply a neutralizing bias to the electrophotographic photosensitive member. For example, a neutralizing lamp is preferably used. Can be mentioned.

The cleaning step is a step of removing the toner remaining on the electrophotographic photosensitive member, and can be suitably performed by a cleaning unit. In addition, it is also possible to employ a method in which the charge of the residual toner is made uniform by the rubbing member and collected by the developing roller without using the cleaning means.
The cleaning means is not particularly limited as long as it can remove the electrophotographic toner remaining on the electrophotographic photosensitive member, and can be appropriately selected from known cleaners. For example, a magnetic brush cleaner Suitable examples include electrostatic brush cleaners, magnetic roller cleaners, blade cleaners, brush cleaners, web cleaners, and the like.

-Lubricant application process and lubricant application means-
The lubricant applying step is a step of applying a lubricant to the surface of the electrophotographic photosensitive member, and is performed by a lubricant applying unit. The lubricant applying means is preferably provided downstream of the cleaning means in the rotation direction of the electrophotographic photosensitive member.
The lubricant applying unit includes a lubricant supplying unit that supplies a lubricant onto the electrophotographic photosensitive member, and a lubricant applying unit that applies the supplied lubricant to the surface of the electrophotographic photosensitive member.

As the lubricant application means, an application blade is preferable.
The material for the coating blade is not particularly limited and may be appropriately selected from known materials for cleaning blades according to the purpose. Examples thereof include urethane rubber, hydrin rubber, silicone rubber, and fluororubber. . These may be used individually by 1 type and may use 2 or more types together. In these blades, the contact portion with the electrophotographic photosensitive member may be coated and impregnated with a low coefficient of friction material. Moreover, in order to adjust the hardness of an elastic body, you may disperse fillers, such as an organic filler and an inorganic filler.

The coating blade is fixed to the blade support by any method such as adhesion or fusion so that the tip can be pressed against the surface of the photoreceptor. The thickness of the blade cannot be uniquely defined in view of the force applied by pressing, but is preferably 0.5 mm to 5 mm, and more preferably 1 mm to 3 mm.
Further, the length of the blade protruding from the support and being able to have a deflection, the so-called free length is not unambiguously defined in consideration of the force applied by pressing in the same manner, but preferably 1 mm to 15 mm, 2 mm to 10 mm is more preferable.

  Other configurations of the blade include a method of coating, dipping, etc. a coating layer of resin, rubber, elastomer, etc. on the surface of an elastic metal blade such as a spring plate, if necessary, via a coupling agent, a primer component, etc. It may be formed by heat curing or the like if necessary, and surface polishing or the like may be applied if necessary.

The coating layer contains at least a binder resin and a filler, and further contains other components as necessary.
The binder resin is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include fluorine resins such as PFA, PTFE, FEP, and PVdF; silicone elastomers such as fluorine rubber and methylphenyl silicone elastomer; Is mentioned.

  The thickness of the elastic metal blade is preferably 0.05 mm to 3 mm, more preferably 0.1 mm to 1 mm. In the elastic metal blade, in order to suppress twisting of the blade, a process such as bending may be performed in a direction substantially parallel to the support shaft after the attachment.

  The force for pressing the photosensitive member with the coating blade is sufficient as the lubricant extends to form a layer, and the spring pressure is preferably 1.0N to 10N, more preferably 2.0N to 8.0N.

The lubricant supply means is a brush-like roller that rotates in contact with the electrophotographic photosensitive member, and the brush-like roller scrapes and scrapes the lubricant to supply the lubricant onto the electrophotographic photosensitive member. It is preferable.
In this case, the brush fiber is preferably flexible in order to suppress mechanical stress on the surface of the photoreceptor. The material of the flexible brush fiber is not particularly limited and may be appropriately selected depending on the intended purpose. For example, polyolefin resin (for example, polyethylene, polypropylene); polyvinyl resin or polyvinylidene resin (for example, Polystyrene, acrylic resin, polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polyvinyl ketone); vinyl chloride-vinyl acetate copolymer; styrene-acrylic acid copolymer; styrene- Butadiene resin; fluororesin (eg, polytetrafluoroethylene, polyvinyl fluoride, polyvinylidene fluoride, polychlorotrifluoroethylene); polyester; nylon; acrylic; rayon; ; Polycarbonate; phenolic resins; amino resins (e.g. urea - formaldehyde resins, melamine resins, benzoguanamine resins, urea resins, polyamide resins).
In order to adjust the degree of bending, for example, diene rubber, styrene-butadiene rubber (SBR), ethylene propylene rubber, isoprene rubber, nitrile rubber, urethane rubber, silicone rubber, hydrin rubber, norbornene rubber, etc. may be combined. .

The support for the lubricant supply means includes a fixed mold and a rotatable roll. Examples of the roll-shaped supply member include a roll brush obtained by winding a tape having brush fibers piled around a metal core bar in a spiral shape. The brush fiber has a fiber diameter of about 10 μm to 500 μm, the length of the brush fiber is 1 mm to 15 mm, and the brush density is 10,000 to 300,000 per square inch (1.5 × 10 ^{7 to} 4.5 per square meter). × 10 ⁸ ) is preferable.

  The lubricant supply means preferably uses a high brush density in terms of supply uniformity and supply stability, and a single fiber is produced from several to hundreds of fine fibers. It is preferable. For example, bundling 50 fine fibers of 6.7 decitex (6 denier), such as 333 decitex = 6.7 decitex × 50 filament (300 denier = 6 denier × 50 filament), and implanting as one fiber Is preferred.

  Moreover, you may provide a coating layer in the brush surface for the purpose of stabilizing the surface shape of a brush, environmental stability, etc. as needed. As a component constituting the coating layer, it is preferable to use a coating layer component that can be deformed according to the bending of the brush fiber. The coating layer component is not particularly limited as long as it is a material that can maintain flexibility, and can be appropriately selected according to the purpose. For example, polyethylene, polypropylene, chlorinated polyethylene, chlorosulfonated polyethylene, etc. Polyolefin resin: Polystyrene such as polystyrene, acrylic (for example, polymethyl methacrylate), polyacrylonitrile, polyvinyl acetate, polyvinyl alcohol, polyvinyl butyral, polyvinyl chloride, polyvinyl carbazole, polyvinyl ether, polybiliketone, or polyvinylidene resin such as polyvinyl chloride-acetic acid Vinyl copolymer; silicone resin composed of organosiloxane bonds or modified products thereof (modified products such as alkyd resin, polyester resin, epoxy resin, polyurethane resin, etc.); Fluororesins such as oloalkyl ether, polyfluorovinyl, polyfluorovinylidene, polychlorotrifluoroethylene; polyamides; polyesters; polyurethanes; polycarbonates; amino resins such as urea-formaldehyde resins; epoxy resins or composite resins thereof It is done.

  A metal soap is suitable as the lubricant. Examples of the metal soap include zinc stearate, barium stearate, lead stearate, iron stearate, nickel stearate, cobalt stearate, copper stearate, strontium stearate, calcium stearate, cadmium stearate, magnesium stearate, Zinc oleate, manganese oleate, iron oleate, cobalt oleate, lead oleate, magnesium oleate, copper oleate, palmitic acid, cobalt zinc palmitate, copper palmitate, magnesium palmitate, aluminum palmitate, palmitate Calcium, lead caprylate, lead caproate, zinc linolenate, cobalt linolenate, calcium linolenate, cadmium ricolinolenate, candelilla wax, carnauba wax Rice wax, Japan wax, jojoba oil, beeswax, lanolin and the like. These may be used individually by 1 type and may use 2 or more types together. Among these, zinc stearate, aluminum stearate, and calcium stearate are particularly preferable.

  As a method for molding the lubricant into a certain shape, for example, a prismatic shape or a cylindrical shape, a publicly known method can be used as a method for molding a solid substance. For example, a melt molding method, a powder molding method, a hot press can be used. Examples thereof include a molding method, a cold isostatic pressing method (CIP), and a hot isostatic pressing method (HIP).

  The recycling step is a step of recycling the toner removed by the cleaning step to the developing unit, and can be suitably performed by the recycling unit. There is no restriction | limiting in particular as said recycling means, A well-known conveyance means etc. are mentioned.

The control step is a step of controlling each of the steps, and can be suitably performed by a control unit.
The control means is not particularly limited as long as the movement of each means can be controlled, and can be appropriately selected according to the purpose. Examples thereof include devices such as a sequencer and a computer.

Here, FIG. 4 is a schematic view showing an example of the image forming apparatus of the present invention. In FIG. 4, an electrophotographic photoreceptor 1 is the electrophotographic photoreceptor of the present invention. In FIG. 4, the photosensitive member 1 has a drum shape, but may have a sheet shape or an endless belt shape.
The charging charger 3, the pre-transfer charger 7, the transfer charger 10, the separation charger 11, and the pre-cleaning charger 13 are non-contact corona discharge type charging means such as corotron, scorotron, solid state charger (solid state charger), etc. Is used.

As the transfer means, the above-mentioned charger can be generally used, but a combination of the transfer charger 10 and the separation charger 11 as shown in FIG. 4 is effective.
Further, as light sources such as the exposure unit 5 and the charge removal lamp 2, light emitted from a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), an electroluminescence (EL), or the like. All things can be used. Various types of filters such as a sharp cut filter, a band pass filter, a near infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter can be used to irradiate only light in a desired wavelength range.
In addition to the steps shown in FIG. 4, the light source and the like are provided with a transfer step, a static elimination step, a cleaning step, or a pre-exposure step that uses light irradiation, so that the photosensitive member is irradiated with light.

  Next, the toner image developed on the photosensitive member 1 by the developing unit 6 is transferred to the recording medium 9, but not all is transferred, and toner remaining on the photosensitive member 1 is also generated. Such residual toner is removed from the photoreceptor by a cleaning unit 16 including a fur brush 14 and a blade 15. Cleaning may be performed only with a cleaning brush, and a known brush such as a fur brush or a mag fur brush is used as the cleaning brush.

  When a positive (negative) charge is applied to the electrophotographic photosensitive member and image exposure is performed, a positive (negative) electrostatic latent image is formed on the surface of the photosensitive member. When this is developed with negative (positive) polarity toner (electrodetection fine particles), a positive image can be obtained, and when developed with positive (negative) polarity toner, a negative image can be obtained. As the developing means, known means are used.

  The wavelength of the static elimination lamp 2 as the static elimination means may be in the wavelength region where the photoconductor has photosensitivity, and is preferably on the long wavelength side in the practical photosensitivity wavelength region of the photoconductor.

Various conditions of the cleaning blade include a blade contact angle of 10 to 30 degrees, a contact pressure of 0.3 to 4 g / mm, a rubber hardness of 60 to 70 degrees, a rebound resilience, 30 to 70%, and a Young's modulus. A range of 30 to 60 kgf / cm ² , a thickness of 1.5 to 3.0 mm, a free length of 7 to 12 mm, and a blade edge biting amount of 0.2 to 2 mm is preferable, and urethane is a material that satisfies such physical properties. A rubber blade is particularly suitable.

  Next, conventional lubricant applying means will be described. As shown in FIG. 5, a lubricant applying device 30 for applying a lubricant to the photoreceptor 1 is provided in the toner cleaning means 16 of FIG. Provided. In this lubricant applying device 30, a solid lubricant 33 is disposed near the photoreceptor 1, and a brush roller 34 is disposed in contact with both the photoreceptor 1 and the solid lubricant 33. When supplying the lubricant, the brush-like roller 34 is rotated so that the solid lubricant 33 is scraped off by the brush-like roller 34, and the solid lubricant 33 adhered to the brush-like roller 34 is applied to the surface of the photoreceptor 1. It is configured.

  The lubricant applying device 30 shown in FIG. 5 applies the lubricant to the surface of the photosensitive member where the toner remains without being removed. Here, the portion corresponding to the character portion of the image originally carried on the surface of the photosensitive member has a large amount of residual toner on the surface of the photosensitive member even after transfer to the recording medium, and the portion other than the character portion is substantially There is no residual toner. Since a large amount of residual toner adheres to the toner, a large amount of lubricant is scraped off by the brush roller and a cleaning blade at the cleaning position, so that the lubricant is applied on the surface of the photoconductor after passing through the cleaning position. The amount tends to be biased. In particular, when the same image is output continuously, such a bias may become prominent because the portion of the photoconductor surface where the residual toner is large is always the same. Further, since residual toner adheres to an application member such as a brush roller, the brush roller becomes dirty, and it is difficult to keep applying the lubricant uniformly over a long period of time. If a uniform lubricant layer cannot be formed on the surface of the photoreceptor, the surface static friction coefficient (μ) may be biased or may not be low enough to transfer toner, resulting in uneven transfer. Abnormal images such as missing characters, bug eaters, blurred images, and blurring occur. Therefore, it is necessary to press the solid lubricant strongly against the brush roller to increase the amount of lubricant supplied to the photoreceptor.

  Also, if the cleaning blade 15 shown in FIG. 5 is provided upstream of the brush-shaped roller 34 in the rotational direction of the photosensitive member and the lubricant is applied after cleaning, the applied lubricant is scraped off by the brush-shaped roller and the cleaning blade. Therefore, it is possible to prevent problems with the configuration of the post-application cleaning. However, when the surface of the photoreceptor to which the lubricant is applied enters the transfer position as it is and transfer is performed, an abnormal image is generated even though the static friction coefficient (μ) of the surface is within an appropriate range. This is because the lubricant particles are not fine enough to form a uniform layer just by being applied, and therefore the layer thickness is uneven on the surface of the photoreceptor, which affects the transferability of the toner. If a uniform lubricant layer cannot be formed on the surface of the photoconductor, the static friction coefficient (μ) on the surface will be non-uniform, or it will not be low enough to transfer toner, resulting in transfer unevenness and character Abnormal images such as voids, bug eaters, blurred images, and blurring occur.

Next, the configuration of the cleaning device 48 of the present invention shown in FIG. 6 will be described. The cleaning device 48 includes a cleaning blade 48a and a support member 48c. The cleaning blade 48a is formed by forming a rubber such as urethane rubber or silicone rubber into a plate shape, the edge of which is in contact with the surface of the photoreceptor 1, and removes the toner on the photoreceptor 1 remaining after transfer. To do.
The cleaning blade 48a is attached to and supported by a support member 48c made of metal, plastic, ceramic, or the like, and is installed at an angle shown in FIG.

The lubricant applying device 43 is disposed outside the downstream side of the cleaning device 48, and a cleaning blade 48a is disposed on the upstream side in the movement direction of the photoreceptor 1, and a lubricant application blade 43e is disposed on the downstream side. The residual toner is removed by the cleaning blade 48a, and the lubricant applied by the lubricant applying device 43 is applied to the surface of the photosensitive member 1 in a clean state. Thereafter, the lubricant applying blade 43e rubs the surface of the photosensitive member 1. Thus, a thin layer of lubricant can be formed on the surface of the photoreceptor 1.
The lubricant application blade 43e is attached to and supported by a support member 43c made of metal, plastic, ceramic, or the like, and is installed at an angle shown in FIG.
In FIG. 6, the lubricant application blade 43e is in contact with the photoconductor by the trail, but the application blade may be in contact in the counter direction.

  The lubricant applying device 43 in FIG. 6 will be described in more detail. The lubricant applying device 43 is provided outside the downstream side of the photoconductor cleaning device 48, and a solid lubricant 43 b and a brush-like roller 43 a as a brush-like member for applying the solid lubricant 43 b to the photoconductor 1. And. The solid lubricant 43b is obtained by dissolving a lubricant additive mainly composed of zinc stearate and then cooling and solidifying it, and is molded into a bar shape. The solid lubricant 43b is held by the lubricant holding member 43d, and the solid lubricant 43b is pressed against the brush roller 43a via the lubricant holding member 43d by a pressure spring attached to the housing 43f of the coating apparatus. . The brush-like roller 43a is provided in contact with the photosensitive member 1, and by the rotation of the brush-like roller 43a, the solid lubricant 43b is scraped to the brush-like roller 43a side, and the lubricant attached to the brush-like roller 43a is photosensitive. It adheres to the surface of the photoreceptor 1 from the contact portion with the body 1. Thereafter, the lubricant is made uniform by the application blade 43e. Further, the supply amount of the lubricant to the photoconductor can be controlled by the pressing force of the pressure spring that presses the solid lubricant against the brush roller.

  The lubricant application device as shown in FIG. 6 makes it possible to apply the lubricant uniformly in a thin layer with a small amount of supplied lubricant.

  As the solid lubricant 43b, a dry solid hydrophobic lubricant can be used. As the solid hydrophobic lubricant, zinc stearate, aluminum stearate, calcium stearate and the like are suitable.

Next, FIG. 7 is a schematic view showing an example of an electrophotographic process according to the present invention. The photoreceptor 21 has at least a photosensitive layer, and contains the compound represented by any one of the general formulas (1) and (2) and a filler. The photosensitive member 21 is driven by driving rollers 22a and 22b, and charging by a charger 23, image exposure by a light source 24, development (not shown), transfer using a transfer charger 25, cleaning by a brush 27, and static elimination by a light source 28 are repeatedly performed. Is called.
In the electrophotographic process shown in FIG. 7, the light irradiation process includes image exposure, pre-cleaning exposure, and static elimination exposure. In addition, pre-transfer exposure, pre-exposure of image exposure, and other known light irradiation processes are performed. It is also possible to irradiate the photoconductor with light.

  FIG. 8 is a diagram showing an example of another embodiment of the present invention. In FIG. 8, the photosensitive drum 56 is driven to rotate counterclockwise in the drawing, and the surface thereof is uniformly charged by a charging charger 53 using a corotron, a scorotron, etc. The electrostatic latent image is carried by scanning with the laser beam L emitted from the apparatus. Since this scanning is performed based on single-color image information obtained by decomposing a full-color image into yellow, magenta, cyan, and black color information, a static color for yellow, magenta, cyan, or black is displayed on the photosensitive drum 56. An electrostatic latent image is formed. A revolver developing unit 50 is disposed on the left side of the photosensitive drum 56 in the drawing. This has a yellow developing device, a magenta developing device, a cyan developing device, and a black developing device in a rotating drum-shaped housing, and each developing device is moved to a developing position facing the photosensitive drum 56 by rotation. Move sequentially. The yellow developing unit, magenta developing unit, cyan developing unit, and black developing unit develop the electrostatic latent image by attaching yellow toner, magenta toner, cyan toner, and black toner, respectively.

On the photosensitive drum 56, electrostatic latent images for yellow, magenta, cyan, and black are sequentially formed. These are sequentially developed by the developing units of the revolver developing unit 50 to become a yellow toner image, a magenta toner image, a cyan toner image, and a black toner image.
An intermediate transfer unit is disposed on the downstream side of the photosensitive drum 56 from the development position. This is because the intermediate transfer belt 58 stretched by a tension roller 59a, an intermediate transfer bias roller 57 as a transfer means, a secondary transfer backup roller 59b, and a belt drive roller 59c is driven by rotation of the belt drive roller 59c. Move endlessly clockwise. The yellow toner image, magenta toner image, cyan toner image, and black toner image developed on the photosensitive drum 56 enter an intermediate transfer nip where the photosensitive drum 56 and the intermediate transfer belt 58 are in contact with each other. Then, while being influenced by the bias from the intermediate transfer bias roller 57, the toner image is superimposed on the intermediate transfer belt 58 and intermediately transferred to form a four-color superimposed toner image.

The surface of the photosensitive drum 56 that has passed through the intermediate transfer nip with the rotation is cleaned of the transfer residual toner by the drum cleaning unit 55. The cleaning unit 55 cleans the transfer residual toner with a cleaning roller to which a cleaning bias is applied. However, a cleaning brush such as a fur brush or a mag fur brush, a cleaning blade, or the like may be used.
The surface of the photosensitive drum 56 from which the transfer residual toner has been cleaned is discharged by the discharging lamp 54. As the charge removal lamp 54, a fluorescent lamp, a tungsten lamp, a halogen lamp, a mercury lamp, a sodium lamp, a light emitting diode (LED), a semiconductor laser (LD), an electroluminescence (EL), or the like is used. A semiconductor laser is used as the light source of the laser optical device. About these emitted lights, you may make it use only a desired wavelength range by various filters, such as a sharp cut filter, a band pass filter, a near-infrared cut filter, a dichroic filter, an interference filter, and a color temperature conversion filter.
On the other hand, a registration roller pair 61 that sandwiches a recording medium 60 sent from a paper feeding cassette (not shown) between two rollers can superimpose the recording medium 60 on a four-color superimposed toner image on the intermediate transfer belt 58. Feed toward the secondary transfer nip at the timing. The four-color superimposed toner images on the intermediate transfer belt 58 are collectively secondary-transferred onto the recording medium 60 under the influence of the secondary transfer bias from the paper transfer bias roller 63 in the secondary transfer nip. By this secondary transfer, a full color image is formed on the recording medium 60.

The recording medium 60 on which the full color image is formed is sent to the paper transport belt 64 by the transfer belt 62. The conveyance belt 64 sends the recording medium 60 received from the transfer unit into the fixing device 65. The fixing device 65 conveys the fed recording medium 60 while being sandwiched in a fixing nip formed by the contact between the heating roller and the backup roller. The full color image on the recording medium 60 is fixed on the transfer paper 60 under the influence of the heating from the heating roller and the pressure applied in the fixing nip.
Although not shown, a bias for attracting the recording medium 60 is applied to the transfer belt 62 and the conveyance belt 64. In addition, a paper neutralization charger that neutralizes the recording medium 60 and three belt neutralization chargers that neutralize each belt (intermediate transfer belt 58, transfer belt 62, and conveyance belt 64) are provided. The intermediate transfer unit also includes a belt cleaning unit having the same configuration as that of the drum cleaning unit 55, thereby cleaning the transfer residual toner on the intermediate transfer belt 58.

Next, FIG. 9 is a schematic view showing another embodiment of the present invention. This image forming apparatus is a so-called tandem printer, and does not share the photosensitive drum 80 for each color as shown in FIG. 8, but cyan (C), magenta (M), yellow (Y), and black ( K) photosensitive drums 80Y, 80M, 80C, and 80Bk for the four colors. The drum cleaning unit 85, the charge removal lamp 83, and the charger 84 are also provided with four colors of cyan (C), magenta (M), yellow (Y), and black (K).
In the tandem type, electrostatic latent image formation and development of each color can be performed in parallel, so that the image forming speed can be made much faster than in the revolver type.

  The image forming means in the image forming apparatus described above may be fixedly incorporated in the copying apparatus, facsimile, or printer, but may be incorporated in the image forming apparatus in the form of a process cartridge described below. .

(Process cartridge)
The process cartridge of the present invention has at least one means selected from a charging means, an exposure means, a developing means, a transfer means, a cleaning means, and a static elimination means, and an electrophotographic photosensitive member, and is attached to and detached from the image forming apparatus main body. It is possible.
The electrophotographic photoreceptor is the electrophotographic photoreceptor of the present invention.

Here, FIG. 10 is a schematic diagram showing a configuration of an image forming apparatus provided with the process cartridge of the present invention.
The photoreceptor 101 has at least a photosensitive layer on a support, and the surface protective layer includes a compound represented by any one of the general formulas (1) and (2), a filler, a charge transport material, It contains. Reference numeral 103 denotes a charging unit, 102 denotes a developing unit, 107 denotes a transfer unit, and 105 denotes a cleaning unit.
In the present invention, among the constituent elements such as the photosensitive member 101, the charging unit 303, the developing unit 304, and the cleaning unit 305, at least the photosensitive member 302 and the developing unit 304 are integrally coupled as a process cartridge. The process cartridge can be configured to be detachable from a main body of an image forming apparatus such as a copying machine or a printer.

  By adopting the configuration of the present invention as described above, it is possible to reduce the initial residual potential of the electrophotographic photosensitive member containing the filler in the surface protective layer and realize a higher-speed image forming apparatus. The present invention also provides an electrophotographic photosensitive member, an image forming apparatus, and a process cartridge according to the present invention that can suppress image deterioration and residual potential increase due to image blur and can stably form a high-quality image even after repeated use over a long period. It becomes possible.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

(Synthesis Example 1)
-Synthesis of titanyl phthalocyanine crystals-
The synthesis of titanyl phthalocyanine crystal was performed according to the method described in JP-A-2004-83859. That is, 292 g of 1,3-diiminoisoindoline and 1800 g of sulfolane were mixed, and 20.4 g of titanium tetrabutoxide was added dropwise under a nitrogen stream. After completion of the dropwise addition, the temperature was gradually raised to 180 ° C., and the reaction was carried out by stirring for 5 hours while maintaining the reaction temperature between 170 ° C. and 180 ° C. After the reaction, the mixture was allowed to cool, and the precipitate was filtered and washed with chloroform until the powder turned blue. Next, it was washed several times with methanol, further washed several times with hot water at 80 ° C. and then dried to obtain crude titanyl phthalocyanine.
The obtained crude titanyl phthalocyanine was dissolved in 20 times the amount of concentrated sulfuric acid and added dropwise to 100 times the amount of ice water with stirring, and the precipitated crystals were filtered. Next, washing with ion exchange water (pH: 7.0, specific conductivity: 1.0 μS / cm) is repeated until the washing solution becomes neutral (pH value of ion exchange water after washing is 6.8, specific conductivity). The titanyl phthalocyanine pigment wet cake (water paste) was obtained.

40 g of the obtained wet cake (water paste) was added to 200 g of tetrahydrofuran, and stirred vigorously (2000 rpm) with a homomixer (KENIS, MARKIIf model) at room temperature, and the paste color changed from dark blue to light blue (20 minutes after the start of stirring), the stirring was stopped and filtration under reduced pressure was immediately performed. The crystals obtained on the filtration device were washed with tetrahydrofuran to obtain a wet cake of pigment. This was dried under reduced pressure (5 mmHg) at 70 ° C. for 2 days to obtain 8.5 parts by mass of titanyl phthalocyanine crystals. This is designated as Pigment 1. The solid content concentration of the wet cake was 15% by mass. The crystal conversion solvent was used in a mass ratio of 33 times that of the wet cake.
In addition, the halogen-containing compound is not used for the raw material of the synthesis example 1. When the obtained titanyl phthalocyanine powder was subjected to X-ray diffraction spectrum measurement under the following conditions, the Bragg angle 2θ with respect to the Cu—Kα ray (wavelength 1.542１．５) was 27.2 ± 0.2 °, and the maximum peak and the minimum angle 7 Has a peak at .3 ± 0.2 °, and further has major peaks at 9.4 ± 0.2 °, 9.6 ± 0.2 °, 24.0 ± 0.2 °, and 7 A titanyl phthalocyanine powder having no peak between the peak at 3 ° and the peak at 9.4 ° and further having no peak at 26.3 ° was obtained. The results are shown in FIG.
<X-ray diffraction spectrum measurement conditions>
・ X-ray tube: Cu
・ Voltage: 50kV
・ Current: 30mA
Scanning speed: 2 ° / min Scanning range: 3 ° -40 °
・ Time constant: 2 seconds

  Next, using a PSZ ball having a diameter of 0.5 mm in a commercially available bead mill disperser, the 2-butanone solution in which polyvinyl butyral was dissolved and the above pigment were charged, and the rotor rotation speed was 1200 r. p. m. For 30 minutes to prepare a pigment dispersion.

In the following examples and comparative examples, the oxidation potential of the charge transport material in the photosensitive layer and the surface protective layer was measured as follows.
<Oxidation potential of charge transport material>
A charge transport substance to be measured was dissolved by adding a predetermined amount of methylene chloride and an irrelevant salt (supporting electrolyte) such as tetrabutylammonium perchlorate or tetraethylammonium perchlorate to prepare a test solution. For this test solution, the oxidation potential of the target substance was measured by an electrochemical analysis means such as polarograph or cyclic voltammetry. Regarding the electrochemical analysis, A.I. J. et al. Bard, L .; R. He is familiar with books such as “Electrochemical Methods” by Faulkner published in 1980 by Wiley. In this example, the measurement was performed by a potential scanning method using a potentiostat using a dropping mercury electrode as a working electrode, platinum as a counter electrode, and a saturated sweet potato electrode (SCE) as a reference electrode.

(Comparative Example 1)
-Production of electrophotographic photoreceptor-
On the aluminum cylinder, an undercoat layer coating solution, a charge generation layer coating solution, and a charge transport layer coating solution having the following composition are sequentially applied by dip coating and dried to form an undercoat layer having a thickness of 3.5 μm. A charge generation layer having a thickness of 0.2 μm and a charge transport layer having a thickness of 22 μm were formed. The drying conditions for each layer were 130 ° C. for the undercoat layer, 90 ° C. for the charge generation layer, and 135 ° C. for the charge transport layer, and each layer was dried for 20 minutes.

<Composition of undercoat layer coating solution>
Titanium dioxide powder: 400 parts by mass Melamine resin: 65 parts by mass Alkyd resin: 120 parts by mass 2-butanone: 400 parts by mass

<Composition of charge generation layer coating solution>
-Titanyl phthalocyanine (ionization potential 5.27 eV)-8 parts by mass-Polyvinyl butyral-5 parts by mass-2-butanone-400 parts by mass showing the X-ray diffraction spectrum of Fig. 11

<Composition of charge transport layer coating solution>
Polycarbonate (Z Polyca, manufactured by Teijin Chemicals Ltd.) 10 parts by mass Charge transport material represented by the following structural formula (oxidation potential: 0.89 V vs SCE, melting point: 93.5 ° C.) 7 masses Part
-Silicone oil (100 cSt, manufactured by Shin-Etsu Chemical Co., Ltd.)-0.002 parts by mass-Tetrahydrofuran-100 parts by mass

  Next, a surface protective layer having a thickness of 5.0 μm was formed on the charge transport layer by spray coating a surface protective layer coating solution having the following composition. The drying conditions for the surface protective layer were 150 ° C. and 20 minutes. Thus, an electrophotographic photosensitive member of Comparative Example 1 was produced.

<Composition of surface protective layer coating solution>
Alumina filler (average primary particle size = 0.3 μm, Sumicorundum AA-03, manufactured by Sumitomo Chemical Co., Ltd.) ... 1 part by mass Unsaturated polycarboxylic acid polymer solution (acid value = 180 mgKOH / g, solid content) 50 mass%, BYK-P104, manufactured by BYK Chemie) ... 0.02 mass part 9 ... 0.6 parts by mass
-Charge transport material represented by the following structural formula (oxidation potential: 0.89 V vs SCE, melting point: 93.5 ° C.) 3 parts by mass
・ Polycarbonate (Z Polyca, manufactured by Teijin Chemicals Limited): 5 parts by mass Tetrahydrofuran: 250 parts by mass Cyclohexanone: 70 parts by mass

(Comparative Example 2)
-Production of electrophotographic photoreceptor-
An electrophotographic photoreceptor of Comparative Example 2 was produced in the same manner as in Comparative Example 1, except that the surface protective layer coating solution was changed to a surface protective layer coating solution having the following composition in Comparative Example 1.
<Composition of surface protective layer coating solution>
Alumina filler (average primary particle size = 0.3 μm, Sumicorundum AA-03, manufactured by Sumitomo Chemical Co., Ltd.) ... 1 part by mass Unsaturated polycarboxylic acid polymer solution (acid value = 180 mgKOH / g, solid content) 50 mass%, BYK-P104, manufactured by BYK Chemie) ... 0.02 mass part 2 ... 1.8 parts by mass
Charge transport material represented by the following structural formula (oxidation potential: 0.89 V vs SCE, melting point: 93.5 ° C.) 1.8 parts by mass
・ Polycarbonate (Z Polyca, manufactured by Teijin Chemicals Limited): 5 parts by mass Tetrahydrofuran: 250 parts by mass Cyclohexanone: 70 parts by mass

(Comparative Example 3)
-Production of electrophotographic photoreceptor-
In Comparative Example 1, except that the charge transport materials of the charge transport layer and the surface protective layer were changed to charge transport materials represented by the following structural formula (oxidation potential: 0.80 V vs SCE, melting point: 139.5 ° C.). In the same manner as in Example 1, an electrophotographic photoreceptor of Comparative Example 3 was produced.

(Comparative Example 4)
-Production of electrophotographic photoreceptor-
In Comparative Example 2, the charge transport material of the charge transport layer and the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.80 V vs SCE, melting point: 139.5 ° C.). In the same manner as in Example 2, an electrophotographic photoreceptor of Comparative Example 4 was produced.

(Comparative Example 5)
-Production of electrophotographic photoreceptor-
In Comparative Example 1, except that the charge transport material of the charge transport layer and the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.76 V vs SCE, melting point: 165.5 ° C.) In the same manner as in Example 1, an electrophotographic photoreceptor of Comparative Example 5 was produced.

(Comparative Example 6)
-Production of electrophotographic photoreceptor-
In Comparative Example 2, the charge transport material of the charge transport layer and the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.76 V vs SCE, melting point: 165.5 ° C.). In the same manner as in Example 2, an electrophotographic photoreceptor of Comparative Example 6 was produced.

(Comparative Example 7)
-Production of electrophotographic photoreceptor-
In Comparative Example 1, the charge transport materials for the charge transport layer and the surface protective layer are represented by the following structural formulas. An electrophotographic photosensitive member of Comparative Example 7 was produced in the same manner as Comparative Example 1, except that the charge transport material was 52 (oxidation potential: 0.75 V vs SCE, melting point: 193 ° C.).

(Comparative Example 8)
-Production of electrophotographic photoreceptor-
In Comparative Example 2, the charge transport materials for the charge transport layer and the surface protective layer are represented by the following structural formulas. An electrophotographic photosensitive member of Comparative Example 8 was produced in the same manner as in Comparative Example 2, except that the charge transport material was 52 (oxidation potential: 0.75 V vs. SCE, melting point: 193 ° C.).

(Comparative Example 9)
-Production of electrophotographic photoreceptor-
In Comparative Example 1, the charge transport materials for the charge transport layer and the surface protective layer are represented by the following structural formulas. An electrophotographic photoreceptor of Comparative Example 9 was produced in the same manner as Comparative Example 1 except that the charge transport material was 12 (oxidation potential: 0.74 V vs. SCE, melting point: 183 ° C.).

(Comparative Example 10)
-Production of electrophotographic photosensitive member of Comparative Example 10-
In Comparative Example 2, the charge transport materials for the charge transport layer and the surface protective layer are represented by the following structural formulas. An electrophotographic photoreceptor of Comparative Example 10 was produced in the same manner as Comparative Example 2 except that the charge transport material was 12 (oxidation potential: 0.74 V vs SCE, melting point: 183 ° C.).

(Comparative Example 11)
-Production of electrophotographic photoreceptor-
In Comparative Example 1, the charge transport materials for the charge transport layer and the surface protective layer are represented by the following structural formulas. An electrophotographic photosensitive member of Comparative Example 11 was produced in the same manner as Comparative Example 1, except that the charge transport material was 14 (oxidation potential: 0.73 V vs SCE, melting point: 211 ° C.).

(Comparative Example 12)
-Production of electrophotographic photoreceptor-
In Comparative Example 2, the charge transport materials for the charge transport layer and the surface protective layer are represented by the following structural formulas. An electrophotographic photosensitive member of Comparative Example 12 was produced in the same manner as Comparative Example 2, except that the charge transport material was 14 (oxidation potential: 0.73 V vs SCE, melting point: 211 ° C.).

(Comparative Example 13)
-Production of electrophotographic photoreceptor-
Comparative Example 1 was the same as Comparative Example 1 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.80 V vs SCE, melting point: 139.5 ° C.). Thus, an electrophotographic photosensitive member of Comparative Example 13 was produced.

(Comparative Example 14)
-Production of electrophotographic photoreceptor-
Comparative Example 3 was the same as Comparative Example 3 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.76 V vs SCE, melting point: 165.5 ° C.). Thus, an electrophotographic photosensitive member of Comparative Example 14 was produced.

Example 1
-Production of electrophotographic photoreceptor-
Comparative Example 7 was the same as Comparative Example 7 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.89 V vs SCE, melting point: 93.5 ° C.). Thus, an electrophotographic photosensitive member of Example 1 was produced.

(Example 2)
-Production of electrophotographic photoreceptor-
Comparative Example 8 was the same as Comparative Example 8 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.89 V vs SCE, melting point: 93.5 ° C.). Thus, an electrophotographic photosensitive member of Example 2 was produced.

(Example 3)
-Production of electrophotographic photoreceptor-
Comparative Example 9 was the same as Comparative Example 9 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.89 V vs SCE, melting point: 93.5 ° C.). Thus, an electrophotographic photosensitive member of Example 3 was produced.

Example 4
-Production of electrophotographic photoreceptor-
Comparative Example 10 was the same as Comparative Example 10 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.89 V vs SCE, melting point: 93.5 ° C.). Thus, an electrophotographic photosensitive member of Example 4 was produced.

(Example 5)
-Production of electrophotographic photoreceptor-
Comparative Example 11 was the same as Comparative Example 11 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.89 V vs SCE, melting point: 93.5 ° C.). Thus, an electrophotographic photosensitive member of Example 5 was produced.

(Example 6)
-Production of electrophotographic photoreceptor-
Comparative Example 12 was the same as Comparative Example 12 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.89 V vs SCE, melting point: 93.5 ° C.). Thus, an electrophotographic photosensitive member of Example 6 was produced.

(Example 7)
-Production of electrophotographic photoreceptor-
Comparative Example 7 was the same as Comparative Example 7 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.80 V vs SCE, melting point: 139.5 ° C.). Thus, an electrophotographic photosensitive member of Example 7 was produced.

(Example 8)
-Production of electrophotographic photoreceptor-
Comparative Example 8 is the same as Comparative Example 8 except that the charge transport material of the surface protective layer is a charge transport material represented by the following structural formula (oxidation potential: 0.80 V vs SCE, melting point: 139.5 ° C.). Thus, an electrophotographic photosensitive member of Example 8 was produced.

Example 9
-Production of electrophotographic photoreceptor-
Comparative Example 9 was the same as Comparative Example 9 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.80 V vs SCE, melting point: 139.5 ° C.). Thus, an electrophotographic photosensitive member of Example 9 was produced.

(Example 10)
-Production of electrophotographic photosensitive member of Example 10-
Comparative Example 10 was the same as Comparative Example 10 except that the charge transport material for the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.80 V vs SCE, melting point: 139.5 ° C.). Thus, an electrophotographic photosensitive member of Example 10 was produced.

(Example 11)
-Production of electrophotographic photoreceptor-
Comparative Example 11 was the same as Comparative Example 11 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.80 V vs SCE, melting point: 139.5 ° C.). Thus, an electrophotographic photosensitive member of Example 11 was produced.

(Example 12)
-Production of electrophotographic photoreceptor-
Comparative Example 12 was the same as Comparative Example 12 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.80 V vs SCE, melting point: 139.5 ° C.). Thus, an electrophotographic photosensitive member of Example 12 was produced.

(Example 13)
-Production of electrophotographic photoreceptor-
Comparative Example 7 was the same as Comparative Example 7 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.76 V vs SCE, melting point: 165.5 ° C.). Thus, an electrophotographic photosensitive member of Example 13 was produced.

(Example 14)
-Production of electrophotographic photoreceptor-
Comparative Example 8 was the same as Comparative Example 8 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.76 V vs SCE, melting point: 165.5 ° C.). Thus, an electrophotographic photosensitive member of Example 14 was produced.

(Example 15)
-Production of electrophotographic photoreceptor-
Comparative Example 9 was the same as Comparative Example 9 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.76 V vs SCE, melting point: 165.5 ° C.). Thus, an electrophotographic photosensitive member of Example 15 was produced.

(Example 16)
-Production of electrophotographic photoreceptor-
Comparative Example 10 was the same as Comparative Example 10 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.76 V vs SCE, melting point: 165.5 ° C.). Thus, an electrophotographic photosensitive member of Example 16 was produced.

(Example 17)
-Production of electrophotographic photoreceptor-
Comparative Example 11 was the same as Comparative Example 11 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.76 V vs SCE, melting point: 165.5 ° C.). Thus, an electrophotographic photosensitive member of Example 17 was produced.

(Example 18)
-Production of electrophotographic photoreceptor-
Comparative Example 12 was the same as Comparative Example 12 except that the charge transport material of the surface protective layer was a charge transport material represented by the following structural formula (oxidation potential: 0.76 V vs SCE, melting point: 165.5 ° C.). Thus, an electrophotographic photosensitive member of Example 18 was produced.

(Example 19)
-Production of electrophotographic photoreceptor-
In Comparative Example 1, the charge transport material of the charge transport layer is represented by No. 1 represented by the following structural formula. No. 7 charge transport material (oxidation potential: 0.71 V vs SCE, melting point: 214 ° C.), and the charge transport material of the surface protective layer is a charge transport material represented by the following structural formula (oxidation potential: 0.80 V vs SCE, The electrophotographic photosensitive member of Example 19 was produced in the same manner as in Comparative Example 1 except that the melting point was 139.5 ° C.
However, Me represents a methyl group.

(Example 20)
-Production of electrophotographic photoreceptor-
In Comparative Example 1, the charge transport material of the charge transport layer is represented by No. 1 represented by the following structural formula. 5 (oxidation potential: 0.67 V vs. SCE, melting point: 178 ° C.), and the charge transport material of the surface protective layer is represented by the following structural formula (oxidation potential: 0.80 V vs. SCE, The electrophotographic photosensitive member of Example 20 was produced in the same manner as in Comparative Example 1 except that the melting point was 139.5 ° C.
However, Me represents a methyl group.

(Example 21)
-Production of electrophotographic photoreceptor-
In Example 9, the electrophotographic photosensitive member of Example 21 was produced in the same manner as in Example 9 except that the thickness of the surface protective layer was 8 μm.

(Example 22)
-Production of electrophotographic photoreceptor-
In Example 9, the electrophotographic photosensitive member of Example 22 was produced in the same manner as in Example 9 except that the thickness of the surface protective layer was 2 μm.

(Example 23)
-Production of electrophotographic photoreceptor-
In Example 9, the electrophotographic photoreceptor of Example 23 was produced in the same manner as in Example 9, except that the amount of the charge transport material added to the charge transport layer was 8.5 parts by mass.

(Example 24)
-Production of electrophotographic photoreceptor-
In Example 11, the electrophotographic photosensitive member of Example 24 was produced in the same manner as in Example 11 except that the amount of the charge transport material added to the charge transport layer was 8.5 parts by mass.

(Example 25)
-Production of electrophotographic photoreceptor-
In Example 9, the electrophotographic photosensitive member of Example 25 was produced in the same manner as in Example 9 except that the amount of the charge transport material added to the charge transport layer was 10 parts by mass.

(Example 26)
-Production of electrophotographic photoreceptor-
In Example 11, the electrophotographic photosensitive member of Example 26 was produced in the same manner as in Example 11 except that the amount of the charge transport material added to the charge transport layer was 10 parts by mass.

(Example 27)
-Production of electrophotographic photoreceptor-
In Example 23, the same procedure as in Example 23 was performed, except that an additive represented by the following structural formula (melting point: 69 ° C.) was added to the charge transport layer in an amount of 2.5 mass% with respect to the charge transport material of the charge transport layer. Thus, an electrophotographic photosensitive member of Example 27 was produced.

(Example 28)
-Production of electrophotographic photoreceptor-
Example 24 is the same as Example 24 except that 2.5% by mass of an additive represented by the following structural formula (melting point: 62.5 ° C.) is added to the charge transport layer in the charge transport layer. In the same manner as described above, an electrophotographic photoreceptor of Example 28 was produced.

(Example 29)
-Production of electrophotographic photoreceptor-
In Example 23, the same procedure as in Example 23 was performed, except that an additive represented by the following structural formula (melting point: 69 ° C.) was added to the charge transport layer in an amount of 5 mass% with respect to the charge transport material of the charge transport layer. An electrophotographic photoreceptor of Example 29 was produced.

(Example 30)
-Production of electrophotographic photoreceptor-
In Example 24, it was the same as Example 24 except that 5 mass% of the additive (melting point: 62.5 ° C.) represented by the following structural formula was added to the charge transport layer in the charge transport layer. Thus, an electrophotographic photosensitive member of Example 30 was produced.

(Example 31)
-Production of electrophotographic photoreceptor-
In Example 23, the same procedure as in Example 23 was performed, except that an additive represented by the following structural formula (melting point: 137.5 ° C.) was added to the charge transport layer in an amount of 5 mass% with respect to the charge transport material of the charge transport layer. Thus, an electrophotographic photosensitive member of Example 31 was produced.

(Example 32)
-Production of electrophotographic photoreceptor-
In Example 23, the same procedure as in Example 23 was performed, except that 2.5% by mass of each of the two additives represented by the following structural formula was added to the charge transporting layer in the charge transporting layer. An electrophotographic photoreceptor of Example 32 was produced.
(Melting point: 69 ° C)
(Melting point: 137.5 ° C)

(Example 33)
-Production of electrophotographic photoreceptor-
In Example 24, the same procedure as in Example 24 was performed, except that 2.5% by mass of each of the two additives represented by the following structural formula was added to the charge transporting layer in the charge transporting layer. An electrophotographic photosensitive member of Example 33 was produced.
(Melting point: 62.5 ° C)
(Melting point: 69 ° C)

(Example 34)
-Production of electrophotographic photoreceptor-
In Example 9, the same procedure as in Example 9 was performed, except that 10% by mass of the additive (melting point: 69 ° C.) represented by the following structural formula was added to the charge transporting layer in the charge transporting layer. An electrophotographic photoreceptor of Example 34 was produced.

(Example 35)
-Production of electrophotographic photoreceptor-
Example 11 is the same as Example 11 except that 10% by mass of an additive represented by the following structural formula (melting point: 62.5 ° C.) is added to the charge transporting layer in the charge transporting layer. Thus, an electrophotographic photosensitive member of Example 35 was produced.

(Example 36)
-Production of electrophotographic photoreceptor-
In Example 9, the same manner as in Example 9 except that 10% by mass of the additive (melting point: 137.5 ° C.) represented by the following structural formula was added to the charge transporting layer in the charge transporting layer. Thus, an electrophotographic photosensitive member of Example 36 was produced.

  Table 1 summarizes the charge transport materials used in the electrophotographic photoreceptors of Comparative Examples 1 to 14 and Examples 1 to 36 manufactured as described above, the characteristics of the additives, and the amounts added.

* In the table, the oxidation potential difference represents (oxidation potential of the charge transport material in the surface protective layer) − (oxidation potential of the charge transport material in the charge transport layer).

<Evaluation by image forming apparatus>
Each of the electrophotographic photosensitive members of Comparative Examples 1 to 14 and Examples 1 to 36 manufactured as described above is mounted on a process cartridge, a charging method is a corona charging method (scorotron type), and an image exposure light source is a semiconductor laser of 780 nm. Using a modified digital writing type full color printer (IPSiO CX8100, manufactured by Ricoh Co., Ltd.), the dark part potential was set to 800 (-V) and then adjusted to a laser image surface energy of 0.43 (μJ / cm ² ). Thereafter, 50,000 sheets of a running test for outputting a test image corresponding to 600 dpi, an A4 horizontal size, and an image area ratio of 5% were performed, and the image quality (character blur) of the image being printed was evaluated visually. Further, the light portion potential VL at the initial stage and after printing 50,000 sheets was measured. Furthermore, the amount of wear was evaluated from the difference in film thickness at the initial stage and after printing 50,000 sheets using an eddy current film thickness meter (Fischer Scope MMS, manufactured by Fischer). The results are shown in Table 2-1 and Table 2-2.

<Image blur evaluation>
A Teflon (registered trademark) tape is applied to a part of each electrophotographic photosensitive member obtained and left in a desiccator adjusted to a nitrogen oxide gas concentration of 50 ppm for 4 days. IPSiO CX8100 modified machine, manufactured by Ricoh Co., Ltd.). The difference in image density between the tape application part and the non-tape part was evaluated as an index of image blur. The image density was measured with a colorimeter (X-Rite 939, manufactured by X-Rite). The results are shown in Table 2-1 and Table 2-2.

<Crack evaluation>
The surface of the photoreceptor was visually observed, and rank evaluation was performed according to the following criteria. The results are shown in Table 2-1 and Table 2-2.
〔Evaluation criteria〕
Rank 5: No cracking Rank 4: Something that looks like a crack looks a little Rank 3: A thing that seems to be a crack can be confirmed, but the number is small Rank 2: A crack can be clearly confirmed, but the number is small Rank 1: A crack can be clearly confirmed , Many occur on the entire surface.
In addition, after the evaluation by the above image forming apparatus, it was confirmed whether or not the crack appeared as an abnormal image. The results are shown in the abnormal image column due to cracks in Table 2-1 and Table 2-2.

From the results of Tables 2-1 and 2-2, in Comparative Examples 1 to 12, the charge represented by any one of the general formulas (3) and (4) is high in hole mobility and low in oxidation potential. Inclusion of a transport material in the photosensitive layer and the surface protective layer is effective in reducing initial VL and suppressing VL increase due to repeated use, but due to ozone, NOx, or other oxidizing substances generated by repeated use and the surrounding environment. Image blurring was noticeable. Further, it has been found that image blur tends to occur as the oxidation potential of the charge transport material contained in the surface protective layer decreases. In Comparative Examples 13 and 14, the initial VL was high, and the increase in VL due to repeated use was large.
On the other hand, in Examples 1 to 36, the photosensitive layer contains a charge transport material having a low oxidation potential, and the surface protective layer contains a charge transport material having a higher oxidation potential than the charge transport material contained in the photosensitive layer. Then, it was generally considered that the difference in the oxidation potential of the charge transport materials contained in both layers becomes a charge injection barrier, the charge transport efficiency is lowered, and the initial VL and the VL increase during repeated use are increased. Even with such a photosensitive layer and surface protective layer structure, it was found that if the surface protective layer has a thickness of up to about 8 μm, the increase in initial VL and VL during repeated use can be suppressed.
Further, when the photosensitive layer and the surface protective layer are formed using each charge transport material as described above, cracks are likely to occur at the interface between the photosensitive layer and the surface protective layer. Although there are examples that can be visually confirmed but do not affect the image, it is more preferable to suppress cracks in order to increase the durability of the photoreceptor. As shown in Comparative Examples 7 to 12 and Examples 1 to 22, the charge transport material having a melting point of 170 ° C. or lower is used as the surface protective layer, or contained in the photosensitive layer as shown in Examples 22 to 36. Increasing the amount of the charge transporting material to 70% by mass or more based on the resin, and further adding 2.5% by mass to the amount of the charge transporting material contained in the photosensitive layer with a low molecular additive having a melting point of 150 ° C. or less. It was found that the addition of -10% by mass makes it possible to suppress the occurrence of cracks and is more preferable as the structure of the photoreceptor.
As described above, even when the photosensitive layer contains the charge transport material represented by any one of the general formulas (3) and (4), the surface protective layer is more than the charge transport material contained in the photosensitive layer. By containing a charge transporting substance having a high oxidation potential and further containing a compound represented by any one of the general formulas (1) and (2) in the surface protective layer, image blurring is suppressed and repeated use An increase in the residual potential can be suppressed at the same time, and in the electrophotographic photosensitive member containing a filler in the surface protective layer in order to achieve high durability, by adopting the configuration of the present invention, the initial residual potential is reduced, and the image caused by image blurring is reduced. It was confirmed that the deterioration and the increase in residual potential could be solved, and a high-quality image could be obtained stably.

(Examples 37 to 50 and Comparative Examples 15 to 28)
<Evaluation 2 by image forming apparatus>
Each electrophotographic photosensitive member produced as shown in Table 3 is mounted on a process cartridge, the charging method is a corona charging method (scorotron type), and the image exposure light source is a two-dimensional array of 4 × 4 surface emitting lasers. Using a digital writing full color printer (IPSiO CX8100, manufactured by Ricoh Co., Ltd.) modified machine II as an array, after setting the dark part potential to 800 (−V), the laser image plane energy 0.43 (μJ / cm ² ) 50,000 running tests to output test images equivalent to 1200 dpi, A4 horizontal size, and 5% image area ratio were performed, and the image quality (character blur) of the image being printed was evaluated visually. It was. Further, the light portion potential VL at the initial stage and after printing 50,000 sheets was measured. Furthermore, the amount of wear was evaluated from the difference in film thickness at the initial stage and after printing 50,000 sheets using an eddy current film thickness meter (Fischer Scope MMS, manufactured by Fischer). The results are shown in Table 3.

<Image blur evaluation 2>
A Teflon (registered trademark) tape is applied to a part of each electrophotographic photosensitive member obtained and left in a desiccator adjusted to a nitrogen oxide gas concentration of 50 ppm for 4 days. IPSiO CX8100 modified machine II, manufactured by Ricoh Co., Ltd.). The difference in image density between the tape application part and the non-tape part was evaluated as an index of image blur. The image density was measured with a colorimeter (X-Rite 939, manufactured by X-Rite). The results are shown in Table 3.

<Crack evaluation 2>
The surface of the photoreceptor was visually observed, and rank evaluation was performed according to the following criteria. The results are shown in Table 3.
〔Evaluation criteria〕
Rank 5: No cracking Rank 4: Something that looks like a crack looks a little Rank 3: A thing that seems to be a crack can be confirmed, but the number is small Rank 2: A crack can be clearly confirmed, but the number is small Rank 1: A crack can be clearly confirmed , Many occur on the entire surface.
In addition, after the evaluation by the full color printer (IPSiO CX8100 remodeling machine II, manufactured by Ricoh Co., Ltd.) was completed, it was confirmed whether a crack appeared as an abnormal image. The results are shown in the abnormal image column due to cracks in Table 3.

Even in an image forming apparatus using a 1200 dpi surface emitting laser as an exposure light source, from the results in Table 3, the photosensitive layer contains a charge transport material represented by any one of the general formulas (3) and (4). The surface protective layer contains a charge transport material having an oxidation potential higher than that of the charge transport material contained in the photosensitive layer, and is further represented by any one of the general formulas (1) and (2) on the surface protective layer. In the electrophotographic photoreceptor containing the filler in the surface protective layer in order to achieve high durability, image blurring can be suppressed and increase in residual potential due to repeated use can be suppressed at the same time. By adopting the configuration, it was confirmed that the initial residual potential can be reduced, the image deterioration due to image blur and the residual potential increase can be solved, and a high-quality image can be stably obtained.

  The electrophotographic photoreceptor of the present invention realizes a higher-speed image forming apparatus by reducing the initial residual potential, suppresses image deterioration and residual potential increase due to image blur, and can be used for repeated use over a long period of time. Since a high-quality image can be stably formed, it is suitable for an electrophotographic laser printer, a digital copying machine, a full-color copying machine, a full-color laser printer, and the like.

FIG. 1 is a schematic cross-sectional view showing an example of a single layer type electrophotographic photosensitive member of the present invention. FIG. 2 is a schematic cross-sectional view showing an example of the laminated electrophotographic photosensitive member of the present invention. FIG. 3 is a schematic cross-sectional view showing another example of the laminated electrophotographic photosensitive member of the present invention. FIG. 4 is a schematic view showing an example of the image forming apparatus of the present invention. FIG. 5 is a schematic view showing an example of a conventional lubricant applying device. FIG. 6 is a schematic view showing an example of the lubricant applying device of the present invention. FIG. 7 is a schematic view showing another example of the image forming apparatus of the present invention. FIG. 8 is a schematic view showing still another example of the image forming apparatus of the present invention. FIG. 9 is a schematic view showing an example of the tandem type image forming apparatus of the present invention. FIG. 10 is a schematic view showing an example of the process cartridge of the present invention. FIG. 11 is an X-ray diffraction spectrum diagram of the charge generating material used in the examples, where the vertical axis represents the number of counts per second (cps) and the horizontal axis represents the angle (2θ). FIG. 12 is a schematic view showing an example of a multi-beam exposure apparatus used in the present invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Electrophotographic photoreceptor 2 Static elimination lamp 3 Charger charger 5 Exposure part 6 Developing means 7 Charger before transfer 9 Recording medium 10 Transfer charger 11 Separation charger 13 Charger before cleaning 14 Fur brush 15 Blade 16 Cleaning means 21 Photoconductor 22a, 22b Drive roller DESCRIPTION OF SYMBOLS 23 Charger 24 Light source 25 Transfer charger 27 Brush 28 Light source 30 Lubricant provision apparatus 33 Solid lubricant 34 Brush-like roller 43 Lubricant provision apparatus 48 Cleaning apparatus 53 Charge charger 54 Static elimination lamp 56 Photosensitive drum 58 Intermediate transfer belt 60 Recording medium 62 Transfer belt 64 Conveying belt 65 Fixing device 80 Photoconductor drum 83 Static elimination lamp 84 Charge charger 85 Cleaning unit 101 Photoconductor 102 Exposure means 103 Charging means 10 Cleaning means 106 developing means 107 transfer means 201 support 202 photosensitive layer 203 the charge generation layer 204 the charge transport layer 210 a surface protective layer 301 light source 301a emitting point 302 the collimating lens 303 a cylindrical lens 304 aperture 305 rotary polygonal mirror (polygon mirror)
306a First scanning lens 306b Second scanning lens 307a First reflecting mirror 307b Second reflecting mirror 307c Third reflecting mirror 308 Photoconductor 309 Scanning line

Claims (26)

An electrophotographic photosensitive member having a support, and at least a photosensitive layer and a surface protective layer on the support,
The surface protective layer contains a filler, a charge transport material, and a compound represented by any one of the following general formulas (1) and (2),
The photosensitive layer contains at least a charge transporting substance, the charge transporting substance in the photosensitive layer has an oxidation potential smaller than that of the charge transporting substance in the surface protective layer, and is represented by the following general formula (3) An electrophotographic photoreceptor, characterized in that
However, in the general formula (1), R ¹ and R ² may be the same as or different from each other, and may have an alkyl group which may have a substituent, and a substituent. Any one of the aryl groups which may be present, and at least one of R ¹ and R ^{2 is} an aryl group which may have a substituent. R ¹ and R ² may be bonded to each other to form a heterocyclic ring containing a nitrogen atom, and the heterocyclic ring may be further substituted with a substituent. Ar represents an arylene group which may have a substituent.
However, in the general formula (2), R ¹ and R ² may be the same as or different from each other, and may have an alkyl group which may have a substituent, and a substituent. Any of the aryl groups that may be present, and R ¹ and R ² may be bonded to each other to form a heterocyclic ring containing a nitrogen atom, and the heterocyclic ring is further substituted with a substituent; Also good. Ar ¹ and Ar ² each represent an arylene group which may have a substituent. l and m each represent an integer of 0 to 3, and l and m are not 0 at the same time. n represents an integer of 1 or 2.
However, in said general formula (3), R < ³ > -R < ⁶ > is the phenyl which may have a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, and a substituent, respectively. Represents any of the groups.
A represents an arylene group which may have a substituent and a substituent represented by the following structural formula (3-1).
However, in said structural formula (3-1), R < ⁷ >, R < ⁸ > and R < ⁹ > are either a hydrogen atom, a C1-C4 alkyl group, a C1-C4 alkoxy group, and a phenyl group. And the phenyl group may be further substituted with a substituent.
B represents any of an aryl group which may have a substituent and a substituent represented by the following structural formula (3-2).
However, in the structural formula (3-2), Ar ³ represents an arylene group which may have a substituent. Ar ⁴ and Ar ⁵ each represents an aryl group which may have a substituent. 2. The electrophotographic photosensitive member according to claim 1, wherein the charge transport material in the photosensitive layer is a distyrylbenzene derivative represented by the following general formula (4).
However, in said general formula (4), R < ¹⁰ > -R < ³⁵ > may mutually be the same and may differ, A hydrogen atom, a C1-C4 alkyl group, C1-C4 It represents either an alkoxy group or a phenyl group which may have a substituent.   The electrophotographic photosensitive member according to claim 1, wherein the photosensitive layer contains a charge generating substance, and the charge generating substance contains a titanyl phthalocyanine pigment.   The titanyl phthalocyanine pigment has a maximum intensity diffraction peak at least 27.2 ° of the black angle (2θ ± 0.2 °) in the X-ray diffraction spectrum using CuKα characteristic X-ray (1.542 °). , 9.4 °, 9.6 °, 24.0 ° with a major peak, 7.3 ° with a minimum angle diffraction peak, between 7.3 ° and 9.4 ° The electrophotographic photosensitive member according to claim 3, which does not have a diffraction peak and does not have a diffraction peak at 26.3 °.   The electrophotographic photosensitive member according to any one of claims 1 to 4, wherein a difference between an oxidation potential of the charge transport material in the surface protective layer and an oxidation potential of the charge transport material in the photosensitive layer is 0.01V to 0.20V.   The electrophotographic photosensitive member according to claim 1, wherein the melting point of the charge transport material in the surface protective layer is 170 ° C. or less.   The electrophotographic photosensitive member according to any one of claims 1 to 6, wherein the content of the charge transport material in the photosensitive layer is 65 parts by mass or more with respect to 100 parts by mass of the resin contained in the photosensitive layer.   The photosensitive layer contains an additive having a melting point of 150 ° C. or less, and the content of the additive is 2.5 parts by mass to 10 parts by mass with respect to 100 parts by mass of the charge transport material in the photosensitive layer. 8. The electrophotographic photoreceptor according to any one of 7 above. The electrophotographic photosensitive member according to claim 8, wherein the additive in the photosensitive layer is at least one of compounds represented by the following structural formulas (1) to (3).
  The electrophotographic photoreceptor according to any one of claims 2 to 9, wherein the charge transport material represented by any one of the general formulas (3) and (4) in the photosensitive layer has a melting point of 170 ° C to 240 ° C.   The electrophotographic photosensitive member according to claim 1, wherein the filler contains at least one selected from metal oxides.   The electrophotographic photosensitive member according to claim 1, wherein the filler has an average primary particle size of 0.01 μm to 1.0 μm.   The electrophotographic photosensitive member according to claim 1, wherein a content of the filler in the surface protective layer is 5% by mass to 50% by mass.   The electrophotographic photosensitive member according to claim 1, wherein the surface protective layer contains an organic compound having an acid value of 10 mgKOH / g to 700 mgKOH / g.   The electrophotographic photosensitive member according to claim 1, wherein the surface protective layer has a thickness of 0.1 μm to 10 μm.   The photosensitive layer has a charge generation layer and a charge transport layer, and the charge transport layer contains a charge transport material represented by any one of the general formulas (3) and (4). An electrophotographic photoreceptor according to any one of the above. An electrophotographic photosensitive member; a charging unit that charges the surface of the electrophotographic photosensitive member; an exposing unit that exposes the surface of the charged electrophotographic photosensitive member to form an electrostatic latent image; and An image forming apparatus comprising at least a developing unit that develops a visible image using the developing unit, a transfer unit that transfers the visible image to a recording medium, and a fixing unit that fixes the transferred image transferred to the recording medium Because
An image forming apparatus, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to claim 1.   18. The exposure unit according to claim 17, wherein the exposure unit is one of a semiconductor laser (LD) and a light emitting diode (LED), and an electrostatic latent image is written on the electrophotographic photosensitive member in a digital manner using the exposure unit. Image forming apparatus.   The image forming apparatus according to claim 17, wherein the exposure unit employs a multi-beam exposure method in which a plurality of beam bundles are used to simultaneously expose a plurality of exposure regions.   The image forming apparatus according to claim 19, wherein the light source employed in the multi-beam exposure method is composed of four or more surface-emitting laser arrays.   21. The image forming apparatus according to claim 19, wherein the light source employed in the multi-beam exposure method is composed of four or more surface emitting laser arrays, and the surface emitting lasers are two-dimensionally arranged.   The image forming apparatus according to claim 17, wherein a color image is formed by sequentially superimposing a plurality of colors of visible images on the electrophotographic photosensitive member.   The image forming apparatus according to claim 17, comprising a plurality of electrophotographic photosensitive members, and forming a color image by sequentially superimposing single-color visible images developed on the respective electrophotographic photosensitive members. .   The image forming apparatus has intermediate transfer means for transferring the visible image developed on the electrophotographic photosensitive member to the intermediate transfer member and then transferring the visible image on the intermediate transfer member to the recording medium. The image forming apparatus according to claim 17, wherein the visible images are sequentially superimposed on an intermediate transfer member to form a color image, and the color image is secondarily transferred onto the recording medium at once.   25. The image forming apparatus according to claim 17, wherein the charging unit is a corona charging unit that discharges in a non-contact manner. A process cartridge having at least one means selected from a charging means, an exposure means, a developing means, a transfer means, a cleaning means, and a static elimination means, and an electrophotographic photosensitive member, and is detachable from an image forming apparatus main body. A process cartridge, wherein the electrophotographic photosensitive member is the electrophotographic photosensitive member according to claim 1.